Spider chart, greenness and whiteness assessment of experimentally designed multivariate models for simultaneous determination of three drugs used as a combinatory antibiotic regimen in critical care units: Comparative study

In this study, five earth-friendly spectrophotometric methods using multivariate techniques were developed to analyze levofloxacin, linezolid, and meropenem, which are utilized in critical care units as combination therapies. These techniques were used to determine the mentioned medications in laboratory-prepared mixtures, pharmaceutical products and spiked human plasma that had not been separated before handling. These methods were named classical least squares (CLS), principal component regression (PCR), partial least squares (PLS), genetic algorithm partial least squares (GA-PLS), and artificial neural network (ANN). The methods used a five-level, three-factor experimental design to make different concentrations of the antibiotics mentioned (based on how much of them are found in the plasma of critical care patients and their linearity ranges). The approaches used for levofloxacin, linezolid, and meropenem were in the ranges of 3-15, 8-20, and 5-25 µg/mL, respectively. Several analytical tools were used to test the proposed methods' performance. These included the root mean square error of prediction, the root mean square error of cross-validation, percentage recoveries, standard deviations, and correlation coefficients. The outcome was highly satisfactory. The study found that the root mean square errors of prediction for levofloxacin were 0.090, 0.079, 0.065, 0.027, and 0.001 for the CLS, PCR, PLS, GA-PLS, and ANN models, respectively. The corresponding values for linezolid were 0.127, 0.122, 0.108, 0.05, and 0.114, respectively. For meropenem, the values were 0.230, 0.222, 0.179, 0.097, and 0.099 for the same models, respectively. These results indicate that the developed models were highly accurate and precise. This study compared the efficiency of artificial neural networks and classical chemometric models in enhancing spectral data selectivity for quickly identifying three antimicrobials. The results from these five models were subjected to statistical analysis and compared with each other and with the previously published ones. Finally, the whiteness of the methods was assessed by the recently published white analytical chemistry (WAC) RGB 12, and the greenness of the proposed methods was assessed using AGREE, GAPI, NEMI, Raynie and Driver, and eco-scale, which showed that the suggested approaches had the least negative environmental impact. Furthermore, to demonstrate solvent sustainability, a greenness index using a spider chart methodology was employed.

Electrochemical and optical (bio)sensors for analysis of antibiotic residuals

Antibiotic residuals in foods may lead to crucial health and safety issues in the human body. Rapid and in-time analysis of antibiotics using simple and sensitive techniques is in high demand. Among the most commonly applicable modalities, chromatography-based techniques like HPLC and LC-MS, along with immunological approaches, particularly ELISA have been exampled in the analysis of antibiotics. Despite being highly sensitive, these methods are considerably time-consuming, thus the presence of skilled personnel and costly equipment is essential. Nanomaterial-based (bio)sensors, however, are de novo analytical equipment with some beneficial characteristics, such as simplicity, low price, on-site, high accuracy, and sensitivity for the detection of analytes. This review aimed to collect the latest developments in NM-based sensors and biosensors for the observation of highly used antibiotics like Vancomycin (Van), Linezolid (Lin), and Clindamycin (Clin). The current challenges and developmental perspectives are also debated in detail for future research directions.

Unlocking Amides: A General Method for the Self-Immolative Release of Amide-Containing Molecules

The controlled liberation of molecules from a constructed framework is a subject of profound interest across various chemical fields. It allows for the masking of a molecule's properties and precise deployment upon a single controllable release event. While numerous methodologies have been developed for amines, alcohols, and thiols, approaches for utilising amides as payload-release handles are still in their early stages of development, despite the prevalence of amides in therapeutic compounds and materials. Herein, is presented a comprehensive strategy for the controlled and selective release of a diverse range of amides with stable linkers. The versatility of this approach is demonstrated by its successful application in the targeted release of various amide-containing drugs in their natural form via the use of commonly used trigger motifs, such as dipeptides or glycosides. As a proof of concept, the FDA-approved antibiotic linezolid has been successfully converted into a prodrug form and released selectively only in the presence of the trigger event. Significantly, in its prodrug state, no activity against Mycobacterium tuberculosis was exhibited. Linezolid's full potential was achieved only upon controlled release, where an equipotent efficacy to the free linezolid control was demonstrated, thus emphasising the immense potential of this method.

Fosfomycin as salvage therapy for persistent methicillin-resistant Staphylococcus aureus bacteremia: A case series and review of the literature

Methicillin-resistant Staphylococcus aureus (MRSA) bacteremia can be persistent and refractory; however, the optimal approach for its treatment has not been determined. Although fosfomycin (FOM) has been shown to have synergistic effects with anti-MRSA agents in vitro, clinical experience with FOM combination therapy is limited. Thus, we present cases of persistent MRSA bacteremia that improved with the addition of FOM. In case 1, a 48-year-old man with prosthetic vascular graft infection developed persistent MRSA bacteremia despite vancomycin (VCM) and daptomycin (DAP) administration. On day 46, after the first positive blood culture, we added FOM to DAP. The blood culture became negative on day 53. In case 2, an 85-year-old woman presented with pacemaker-related MRSA bacteremia. She was treated with VCM, followed by DAP and DAP plus rifampicin. However, the bacteremia persisted for 32 days because of difficulties in immediate pacemaker removal. After adding FOM to DAP, the blood culture became negative on day 38. In case 3, a 57-year-old woman developed persistent MRSA bacteremia due to pulmonary valve endocarditis and pulmonary artery thrombosis after total esophagectomy for esophageal cancer. The bacteremia continued for 50 days despite treatment with DAP, followed by VCM, VCM plus minocycline, DAP plus linezolid (LZD), and VCM plus LZD. She was managed conservatively because of surgical complications. After adding FOM to VCM on day 51, the blood culture became negative on day 58. FOM combination therapy may be effective in eliminating bacteria and can serve as salvage therapy for refractory MRSA bacteremia.

Nocardia species distribution and antimicrobial susceptibility within Australia

BACKGROUND

Nocardia is a ubiquitous saprophyte capable of causing human disease. Disease is primarily respiratory or cutaneous, usually acquired via inhalation or inoculation. Under the influence of environmental and host factors, Nocardia incidence and species distribution demonstrate geographical variation.

AIMS

To examine for differences in Nocardia incidence within Western Australia (WA) and analyse species distribution in the context of prior published studies. To analyse antibiogram data from a nationwide passive antimicrobial resistance surveillance program.

METHODS

Retrospective extraction of laboratory data for Western Australian Nocardia isolates over a 21-year period. Analysis of Nocardia antimicrobial susceptibility testing data submitted to the Australian Passive Antimicrobial Resistance Surveillance (APAS) program between 2005 and 2022.

RESULTS

Nine hundred sixty WA isolates were identified, giving an annual incidence of 3.03 per 100 000 population with apparent latitudinal variation. The four most common species identified within WA and amongst APAS isolates were N. nova, N. cyriacigeorgica, N. brasiliensis and N. farcinica. APAS data demonstrated that all species exhibited high rates of susceptibility to linezolid (100%) and trimethoprim-sulfamethoxazole (98%). Amikacin (>90% susceptibility for all species except N. transvalensis) was the next most active parenteral agent, superior to both carbapenems and third-generation cephalosporins. Susceptibility to oral antimicrobials (other than linezolid) demonstrated significant interspecies variation.

CONCLUSIONS

We demonstrate geographical variation in the distribution of Nocardia incidence. Four species predominate in the Australian setting, and nationwide data confirm a high in vitro susceptibility to trimethoprim-sulphamethoxazole and linezolid, justifying their ongoing role as part of first-line empiric therapy.

Polycystic intrahepatic infection caused by Enterococcus casseliflavus: a case report and literature review

BACKGROUND

Enterococcus casseliflavus is a rare pathogenic bacterium that is characterized by vancomycin resistance and can lead to multiple infections in the human body. This report describes a rare case of polycystic intrahepatic infection with E. casseliflavus which necessitated antibiotic treatment and surgical intervention involving cystic drainage.

CASE PRESENTATION

A 59-year-old woman, a long-term hemodialysis patient, was hospitalized due to a 5-day history of fever, abdominal pain, and diarrhea, which were possibly caused by the ingestion of contaminated food. Her blood culture yielded a positive result for E. casseliflavus, and she was initially treated with piperacillin/tazobactam and linezolid. Later, the antibiotic regimen was adjusted to include meropenem and linezolid. Despite treatment, her body temperature remained elevated. However, subsequent blood cultures were negative for E.casseliflavus.Conventional CT scans and ultrasound examinations did not identify the source of infection. However, a PET-CT examination indicated an intrahepatic cyst infection. Following MRI and ultrasound localization, percutaneous intrahepatic puncture and drainage were performed on the 20th day. Fluoroquinolones were administered for 48 days. On the 32nd day, MRI revealed a separation within the infected cyst, leading to a repeat percutaneous drainage at a different site. Subsequently, the patient's temperature returned to normal. The infection was considered resolved, and she was discharged on the 62nd day. Follow-up results have been favorable thus far.

CONCLUSIONS

Based on the findings from this case, it is recommended to promptly conduct PET-CT examination to exclude the possibility of intracystic infection in cases of polycystic liver infection that are challenging to control. Furthermore, timely consideration should be given to puncture drainage in difficult cases.

Drug-resistant tuberculosis is a global cause of concern

The number of patients with drug-resistant tuberculosis (DR-TB) is increasing worldwide. This review summarises the global epidemiology of DR-TB and current treatment challenges. Luckily, novel regimens comprising bedaquiline, pretomanid, linezolid, and moxifloxacin have seemingly mitigated the global threat posed by DR-TB. However, emerging resistance against bedaquiline and pretomanid, among other factors, persists as ongoing concerns in the global fight against DR-TB. While the new regimens are groundbreaking, the sustained development of novel drugs targeting the most resistant forms of tuberculosis is of utmost importance for future efforts against DR-TB.

A Liquid Chromatography-Tandem Mass Spectrometry Method for Simultaneously Determining Meropenem and Linezolid in Blood and Cerebrospinal Fluid

Antibiotic therapy requires appropriate dosage of drugs for effective treatment. Too low antibiotic concentrations may lead to treatment failure and the development of resistant pathogens, whereas overdosing may cause neurological side effects or hemolytic diseases. Meropenem and linezolid are used only in the treatment of serious infections or when other antibiotics are no longer effective as well as for treating central nervous system infections. It is difficult or sometimes even impossible to predict the relation between dosing of antibiotics and its cerebrospinal fluid (CSF) concentration; thus, a method of determining antibiotics not only in the blood but also in the CSF is needed. Analytical method validation is an integral part of good laboratory practice and ensures high accuracy of the results. We performed complete validation process according to the Food and Drug Administration and European Medicine Agency, covering the aspects precision, specificity, accuracy, recovery, limit of detection, limit of quantification, stability, carry-over, and matrix effects. Our liquid chromatography-tandem mass spectrometry method for the simultaneous measurement of meropenem and linezolid in different matrix meets all the acceptance criteria. The method was successfully applied to determine meropenem and linezolid concentrations in serum and CSF samples obtained from children treated with these antibiotics.

Linezolid brain penetration in neurointensive care patients

BACKGROUND

Linezolid exposure in critically ill patients is associated with high inter-individual variability, potentially resulting in subtherapeutic antibiotic exposure. Linezolid exhibits good penetration into the CSF, but its penetration into cerebral interstitial fluid (ISF) is unknown.

OBJECTIVES

To determine linezolid penetration into CSF and cerebral ISF of neurointensive care patients.

PATIENTS AND METHODS

Five neurocritical care patients received 600 mg of linezolid IV twice daily for treatment of extracerebral infections. At steady state, blood and CSF samples were collected from arterial and ventricular catheters, and microdialysate was obtained from a cerebral intraparenchymal probe.

RESULTS

The median fAUC0-24 was 57.6 (24.9-365) mg·h/L in plasma, 64.1 (43.5-306.1) mg·h/L in CSF, and 27.0 (10.7-217.6) mg·h/L in cerebral ISF. The median penetration ratio (fAUCbrain_or_CSF/fAUCplasma) was 0.5 (0.25-0.81) for cerebral ISF and 0.92 (0.79-1) for CSF. Cerebral ISF concentrations correlated well with plasma (R = 0.93, P < 0.001) and CSF levels (R = 0.93, P < 0.001).The median fAUC0-24/MIC ratio was ≥100 in plasma and CSF for MICs of ≤0.5 mg/L, and in cerebral ISF for MICs of ≤0.25 mg/L. The median fT>MIC was ≥80% of the dosing interval in CSF for MICs of ≤0.5 mg/L, and in plasma and cerebral ISF for MICs of ≤0.25 mg/L.

CONCLUSIONS

Linezolid demonstrates a high degree of cerebral penetration, and brain concentrations correlate well with plasma and CSF levels. However, substantial variability in plasma levels, and thus cerebral concentrations, may result in subtherapeutic tissue concentrations in critically ill patients with standard dosing, necessitating therapeutic drug monitoring.

[A multi-center epidemiological study on pneumococcal meningitis in children from 2019 to 2020]

OBJECTIVES

To investigate the clinical characteristics and prognosis of pneumococcal meningitis (PM), and drug sensitivity of Streptococcus pneumoniae (SP) isolates in Chinese children.

METHODS

A retrospective analysis was conducted on clinical information, laboratory data, and microbiological data of 160 hospitalized children under 15 years old with PM from January 2019 to December 2020 in 33 tertiary hospitals across the country.

RESULTS

Among the 160 children with PM, there were 103 males and 57 females. The age ranged from 15 days to 15 years, with 109 cases (68.1%) aged 3 months to under 3 years. SP strains were isolated from 95 cases (59.4%) in cerebrospinal fluid cultures and from 57 cases (35.6%) in blood cultures. The positive rates of SP detection by cerebrospinal fluid metagenomic next-generation sequencing and cerebrospinal fluid SP antigen testing were 40% (35/87) and 27% (21/78), respectively. Fifty-five cases (34.4%) had one or more risk factors for purulent meningitis, 113 cases (70.6%) had one or more extra-cranial infectious foci, and 18 cases (11.3%) had underlying diseases. The most common clinical symptoms were fever (147 cases, 91.9%), followed by lethargy (98 cases, 61.3%) and vomiting (61 cases, 38.1%). Sixty-nine cases (43.1%) experienced intracranial complications during hospitalization, with subdural effusion and/or empyema being the most common complication [43 cases (26.9%)], followed by hydrocephalus in 24 cases (15.0%), brain abscess in 23 cases (14.4%), and cerebral hemorrhage in 8 cases (5.0%). Subdural effusion and/or empyema and hydrocephalus mainly occurred in children under 1 year old, with rates of 91% (39/43) and 83% (20/24), respectively. SP strains exhibited complete sensitivity to vancomycin (100%, 75/75), linezolid (100%, 56/56), and meropenem (100%, 6/6). High sensitivity rates were also observed for levofloxacin (81%, 22/27), moxifloxacin (82%, 14/17), rifampicin (96%, 25/26), and chloramphenicol (91%, 21/23). However, low sensitivity rates were found for penicillin (16%, 11/68) and clindamycin (6%, 1/17), and SP strains were completely resistant to erythromycin (100%, 31/31). The rates of discharge with cure and improvement were 22.5% (36/160) and 66.2% (106/160), respectively, while 18 cases (11.3%) had adverse outcomes.

CONCLUSIONS

Pediatric PM is more common in children aged 3 months to under 3 years. Intracranial complications are more frequently observed in children under 1 year old. Fever is the most common clinical manifestation of PM, and subdural effusion/emphysema and hydrocephalus are the most frequent complications. Non-culture detection methods for cerebrospinal fluid can improve pathogen detection rates. Adverse outcomes can be noted in more than 10% of PM cases. SP strains are high sensitivity to vancomycin, linezolid, meropenem, levofloxacin, moxifloxacin, rifampicin, and chloramphenicol.

Serotonin syndrome: A pharmacovigilance comparative study of drugs affecting serotonin levels

BACKGROUND

Serotonin syndrome is a rare and potentially fatal adverse drug reaction caused by serotonergic drugs and is due to an increase in serotonin concentration or activation of the 5-HT receptor in the central nervous system. We analysed adverse events in the US Food and Drug Administration (FDA) Adverse Event Reporting System (FAERS) data set to investigate the main drug classes related to reports of serotonin syndrome and the reporting risk in relation to age and sex.

METHODS

We analysed data from the FAERS database to evaluate the main drug classes related to reports of the serotonin syndrome, and the reporting risk in relation to age and sex.

RESULTS

We found 8,997 cases of serotonin syndrome; selective serotonin reuptake inhibitors (SSRIs) was the class of drugs with most reports, followed by opioids and other antidepressants. The highest Reporting Odds Ratios (ROR) for drug classes was for monoamine oxidase (MAO) inhibitors (45.99, 95% confidence interval (CI): 41.21-51.33) and SSRIs (32.66, 95% CI: 31.33-34.04), while the ten active substances with the highest ROR were moclobemide, isocarboxazid, oxitriptane, tranylcypromine, melitracen, phenelzine, linezolid, amoxapine, reboxetine and tryptophan; with values of ROR ranging from 44.19 (95% CI: 25.38-76.94) of tryptophan to 388.36 (95% CI: 314.58-479.46) of moclobemide. The ROR for the most commonly involved drugs was higher in the group of older adults (65 > years old), and higher in males.

CONCLUSION

Prescribers need to be vigilant about drugs that can raise serotonin concentration or influence serotonergic neurotransmission, also when using drugs with less well-known risk for serotonin syndrome, like linezolid and triptans.

Antibiotic resistance determination using Enterococcus faecium whole-genome sequences: a diagnostic accuracy study using genotypic and phenotypic data

BACKGROUND

DNA sequencing could become an alternative to in vitro antibiotic susceptibility testing (AST) methods for determining antibiotic resistance by detecting genetic determinants associated with decreased antibiotic susceptibility. Here, we aimed to assess and improve the accuracy of antibiotic resistance determination from Enterococcus faecium genomes for diagnosis and surveillance purposes.

METHODS

In this retrospective diagnostic accuracy study, we first conducted a literature search in PubMed on Jan 14, 2021, to compile a catalogue of genes and mutations predictive of antibiotic resistance in E faecium. We then evaluated the diagnostic accuracy of this database to determine susceptibility to 12 different, clinically relevant antibiotics using a diverse population of 4382 E faecium isolates with available whole-genome sequences and in vitro culture-based AST phenotypes. Isolates were obtained from various sources in 11 countries worldwide between 2000 and 2018. We included isolates tested with broth microdilution, Vitek 2, and disc diffusion, and antibiotics with at least 50 susceptible and 50 resistant isolates. Phenotypic resistance was derived from raw minimum inhibitory concentrations and measured inhibition diameters, and harmonised primarily using the breakpoints set by the European Committee on Antimicrobial Susceptibility Testing. A bioinformatics pipeline was developed to process raw sequencing reads, identify antibiotic resistance genetic determinants, and report genotypic resistance. We used our curated database, as well as ResFinder, AMRFinderPlus, and LRE-Finder, to assess the accuracy of genotypic predictions against phenotypic resistance.

FINDINGS

We curated a catalogue of 228 genetic markers involved in resistance to 12 antibiotics in E faecium. Very accurate genotypic predictions were obtained for ampicillin (sensitivity 99·7% [95% CI 99·5-99·9] and specificity 97·9% [95·8-99·0]), ciprofloxacin (98·0% [96·4-98·9] and 98·8% [95·9-99·7]), vancomycin (98·8% [98·3-99·2] and 98·8% [98·0-99·3]), and linezolid resistance (after re-testing false negatives: 100·0% [90·8-100·0] and 98·3% [97·8-98·7]). High sensitivity was obtained for tetracycline (99·5% [99·1-99·7]), teicoplanin (98·9% [98·4-99·3]), and high-level resistance to aminoglycosides (97·7% [96·6-98·4] for streptomycin and 96·8% [95·8-97·5] for gentamicin), although at lower specificity (60-90%). Sensitivity was expectedly low for daptomycin (73·6% [65·1-80·6]) and tigecycline (38·3% [27·1-51·0]), for which the genetic basis of resistance is not fully characterised. Compared with other antibiotic resistance databases and bioinformatic tools, our curated database was similarly accurate at detecting resistance to ciprofloxacin and linezolid and high-level resistance to streptomycin and gentamicin, but had better sensitivity for detecting resistance to ampicillin, tigecycline, daptomycin, and quinupristin-dalfopristin, and better specificity for ampicillin, vancomycin, teicoplanin, and tetracycline resistance. In a validation dataset of 382 isolates, similar or improved diagnostic accuracies were also achieved.

INTERPRETATION

To our knowledge, this work represents the largest published evaluation to date of the accuracy of antibiotic susceptibility predictions from E faecium genomes. The results and resources will facilitate the adoption of whole-genome sequencing as a tool for the diagnosis and surveillance of antimicrobial resistance in E faecium. A complete characterisation of the genetic basis of resistance to last-line antibiotics, and the mechanisms mediating antibiotic resistance silencing, are needed to close the remaining sensitivity and specificity gaps in genotypic predictions.

FUNDING

Wellcome Trust, UK Department of Health, British Society for Antimicrobial Chemotherapy, Academy of Medical Sciences and the Health Foundation, Medical Research Council Newton Fund, Vietnamese Ministry of Science and Technology, and European Society of Clinical Microbiology and Infectious Disease.

The impact of antibiotic stewardship interventions and patient related factors on antibiotic prescribing in a vascular surgical department

PURPOSE

The development of guidelines tailored to the departments' needs and counselling during ward rounds are important antibiotic stewardship (AS) strategies. The aim was to analyse the impact of AS ward rounds and institutional guidelines as well as patient-related factors on antibiotic use in vascular surgical patients.

METHODS

A retrospective prescribing-analysis of 3 months (P1, P2) before and after implementing weekly AS ward rounds and antimicrobial treatment guidelines was performed. Choice of systemic antibiotics, days of antibiotic therapy and clinical data were obtained from electronic patient records.

RESULTS

During P2, the overall antibiotic consumption as well as the use of last-resort compounds like linezolid and fluoroquinolones decreased distinctly (overall: 47.0 days of therapy (DOT)/100 patient days (PD) vs. 35.3 DOT/100PD, linezolid: 3.7 DOT/100PD vs. 1.0 DOT/100PD, fluoroquinolones: 7.0 DOT/100PD vs. 3.2 DOT/100PD) while narrow-spectrum beta-lactams increased by 48.4%. Courses of antibiotics were de-escalated more often during P2 (30.5% vs. 12.1%, p = 0.011). Only in P2, an antibiotic therapy was initiated in patients suffering from more comorbidities (i.e. higher Charlson Comorbidity Index) more frequently. Other patient factors had no distinct impact on antibiotic prescribing.

CONCLUSION

Weekly AS ward rounds improved adherence to institutional antibiotic treatment guidelines and antibiotic prescribing in vascular surgical patients. Clear patient-related determinants affecting choice of antibiotic therapies could not be identified.

Membrane vesicles derived from Enterococcus faecalis promote the co-transfer of important antibiotic resistance genes located on both plasmids and chromosomes

BACKGROUND

Bacterial membrane vesicles (BMVs) are novel vehicles of antibiotic resistance gene (ARG) transfer in Gram-negative bacteria, but their role in the spread of ARGs in Gram-positive bacteria has not been defined. The purpose of this study was to evaluate the role of MVs in the transmission of antimicrobial resistance in Gram-positive bacteria.

METHODS

A linezolid-resistant Enterococcus faecalis CQ20 of swine origin was selected as the donor strain. Linezolid-susceptible E. faecalis SC032 of human origin, Enterococcus faecium BM4105 and Escherichia coli were selected as recipient strains. The presence of plasmids (pCQ20-1 and pCQ20-2) and an optrA-carrying transposon Tn6674 in CQ20, MVs and vesiculants was verified by WGS or PCR. MVs were isolated with density gradient centrifugation, and MV-mediated transformation was performed to assess the horizontal transferability of MVs. The MICs for CQ20 and its vesiculants were determined by the broth microdilution method.

RESULTS

CQ20-derived MVs (CQ20-MV) were isolated, and PCR identified the presence of two plasmids and the optrA gene in the CQ20-MVs. MV-mediated transformation to E. faecalis SC032 and E. faecium BM4105 was successfully performed, and the WGS data also showed that both plasmids pCQ20-1 and pCQ20-2 and optrA-carrying transposon Tn6674 were transferred to E. faecalis SC032 and E. faecium BM4105, but failed for E. coli. Additionally, vesiculants that had acquired ARGs still had the ability to spread these genes via MVs.

CONCLUSIONS

To our knowledge, this is the first report of MV-mediated co-transfer of ARG-carrying plasmids and transposons in the Gram-positive bacterium E. faecium.

Cost-effectiveness of pretomanid-based regimen for highly drugresistant TB in a low-burden setting

BACKGROUND: Recent clinical findings reported improvement in the treatment outcomes of highly resistant TB (HDR-TB) with the pretomanid (Pa) based regimen. This study aimed to evaluate the cost-effectiveness of the Pa-based regimen for HDR-TB treatment from the perspective of the healthcare sector in the United States.METHODS: A lifelong decision-analytic model was constructed to simulate potential treatment outcomes of 1) the bedaquiline-Pa-linezolid (BPaL) regimen, and 2) the bedaquiline-linezolid (B-L) based regimen in a hypothetical cohort of adult patients with HDR-TB. Primary model outputs were TB-related direct medical costs, qualityadjusted life-years (QALYs) and incremental cost per QALY gained (ICER).RESULTS: In the base-case analysis, the BPaL regimen gained 3.0054 QALYs and saved costs by USD60,433 when compared to the B-L-based regimen. In the probabilistic sensitivity analysis, the BPaL regimen gained higher QALYs at a lower cost in 80.3% of the time, and gained higher QALYs at a higher cost with ICER less than the willingness-to-pay (WTP) threshold (100,000 USD/QALY) in 19.0% of the simulations. The probability of the BPaL regimen being cost-effective was higher than the B-L-based regimen throughout the variation of WTP.CONCLUSION: BPaL therapy is likely the cost-effective option for HDR-TB treatment from the US healthcare sector perspective.

[Distribution and Antibiotic Resistance Analysis of Ocular Bacterial Pathogens at a Tertiary Hospital From 2012 to 2021]

Objective

To analyze the distribution of ocular bacterial pathogens and their antibiotic resistance status at a tertiary-care hospital and to provide a reference for the appropriate use of antibiotics.

Methods

Retrospective analysis was conducted with bacteria isolated from the ophthalmic samples sent for lab analysis at a tertiary-care hospital from 2012 to 2021. The suspected bacterial strains were identified with automated systems for microbial identification and susceptibility analysis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometer. VITEK 2 Compact, an automated microbial identification and antibiotic susceptibility analysis system, was used for antimicrobial susceptibility testing.

Results

A total of 1556 ophthalmology bacteria culture samples were collected, 574 of which showed bacterial growth, presenting an overall positive rate of 36.89%. Of the isolated bacteria, Gram-positive cocci, Gram-positive bacilli, Gram-negative bacilli, and Gram-negative cocci accounted for 63.15% (377/597), 18.76% (112/597), 17.09% (102/597), and 1.00% (6/597), respectively. Among the bacteria isolated in different years over the course of a decade, Gram-positive cocci always turned out to be the main cause of eye infections. Of the Gram-positive cocci, 73.47% (277/377) were isolated from patients with endophthalmitis, with the most important species being Staphylococcus epidermidis, which was followed by Streptococcus viridans. The rest, or 26.53% (100/377), of the Gram-positive cocci were isolated from patients with external eye infections, with the main isolated strains being Staphylococcus epidermidis, Streptococcus viridans, and Staphylococcus aureus. More than 70% of Staphylococcus epidermidis isolated from both endophthalmitis and external eye infections were resistant to methicillin. No strains resistant to vancomycin, linezolid, or tigecycline were detected. Staphylococcus epidermidis isolated from patients with external eye infections had a low rate of resistance to levofloxacin (2/27 or 7.41%), whereas those isolated from patients with endophthalmitis had a higher resistance rate (43/127 or 33.86%). The difference in drug resistance rate between the two groups was statistically significant (P<0.05).

Conclusion

The chief ocular bacterial pathogens identified in a tertiary-care hospital were Gram-positive cocci, among which, Staphylococcus epidermidis was the most common species. The Staphylococcus epidermidis identified in the hospital had a high rate of resistance to oxacillin, but remained highly sensitive to vancomycin, linezolid, and tigecycline. The endophthalmitis caused by Staphylococcus epidermidis in the hospital can be treated empirically with vancomycin and then the treatment plan can be further adjusted according to the results of the drug susceptibility test. However, the establishment of the breakpoint of drug susceptibility test is mainly based on the model of bloodstream infection and has limited reference value for the treatment of eye infection. The required drug distribution concentration at the infection site can be achieved by dose increase or local administration.

Seraph 100 Microbind Affinity Blood Filter Does Not Clear Antibiotics: An Analysis of Antibiotic Concentration Data from PURIFY-OBS

INTRODUCTION

Novel hemoperfusion systems are emerging for the treatment of sepsis. These devices can directly remove pathogens, pathogen-associated molecular patterns, cytokines, and other inflammatory markers from circulation. However, significant safety concerns such as potential antibiotic clearance need to be addressed prior to these devices being used in large clinical studies.

METHODS

Prospective, observational study of 34 participants undergoing treatment with the Seraph 100® Microbind Affinity Blood Filter (Seraph 100) device at 6 participating sites in the USA. Patients were included for analysis if they had a record of receiving an antibiotic concurrent with Seraph 100 treatment. Patients were excluded if there was missing information for blood flow rate. Blood samples were drawn pre- and post-filter at 1 h and 4 h after treatment initiation. These average pre- and post-filter time-concentration observations were then used to estimate antibiotic clearance in L/h (CLSeraph) due to the Seraph 100 device.

RESULTS

Of the 34 participants in the study, 17 met inclusion and exclusion criteria for the antibiotic analysis. Data were obtained for 7 antibiotics (azithromycin, cefazolin, cefepime, ceftriaxone, linezolid, piperacillin, and vancomycin) and one beta-lactamase inhibitor. Mean CLSeraph for the antibiotics investigated ranged from -0.57 to 0.47 L/h. No antibiotic had a CLSeraph statistically significant from 0.

DISCUSSION/CONCLUSION

The Seraph 100 did not significantly clear any measured antibiotic in clinical samples. These data give further evidence to suggest that these therapies may be safely administered to critically ill patients and will not impact concentrations of administered antibiotics.

Global adoption of 6-month drug-resistant TB regimens: Projected uptake by 2026

BACKGROUND

The WHO has issued a call to action urging countries to accelerate the rollout of new WHO-recommended shorter all-oral treatment regimens for drug-resistant TB (DR-TB), which remains a public-health crisis. The all-oral, 6-month BPaL/M regimen comprises 3-4 drugs: pretomanid used in combination with bedaquiline and linezolid, with or without moxifloxacin. This regimen has been recommended by the WHO for use in DR-TB patients instead of ≥9-month (up to 24-month) regimens. This study aims to project this regimen's use, along with its components bedaquiline, pretomanid and linezolid, and other treatments for DR-TB globally through 2026. It is intended to guide global health stakeholders in planning and budgeting for DR-TB interventions. Projected usage could help estimate cost of the individual components of DR-TB regimens over time.

METHODS

Semi-structured interviews were conducted with national TB programme participants in key countries to gather intelligence on established plans and targets for use of various DR-TB treatment regimens from 2023 to 2026. These data informed development of projections for the global use of regimens and drugs.

RESULTS

Consistent global growth in the use of shorter regimens in DR-TB treatment was shown: BPaLM reaching 126,792 patients, BPaL reaching 43,716 patients, and the 9-11-month all-oral bedaquiline-based regimen reaching 13,119 patients by 2026. By 2026, the longer all-oral regimen is projected to be used by 19,262 patients, and individualised treatment regimens by 15,344 patients.

CONCLUSION

The study shows BPaL/M will be used in majority of DR-TB patients by 2024, reaching 78% by 2026. However, national efforts to scale-up, case-finding, monitoring, drug-susceptibility testing, and implementation of new treatments will be essential for ensuring they are accessible to all eligible patients in the coming years and goals for ending TB are met. There is an urgent need to engage communities in capacity building and demand generation.

Evaluation of pathogen distribution and antimicrobial resistance in breast plastic surgery infection

BACKGROUND

The demand for mammaplasty has increased in recent years, and infection remains one of the common and serious post-operative complications. In this study, we analyzed the pathogen distribution and antibiotic susceptibility of breast plastic surgery infections, and compared the differences in pathogenic species between surgical procedures.

METHODS

The number of each species was counted in the microbial samples of breast plastic surgery infections in Plastic Surgery Hospital of Chinese Academy of Medical Sciences from January 2011 to December 2021. The in vitro antibiotic sensitivity testing data were analyzed using WHONET 5.6 software. The surgical techniques, the period of infection, and other details were gathered in accordance with the clinical data.

RESULTS

There were a total of 42 cases included, and 43 different types of pathogenic bacteria, mostly gram-positive bacteria, were found. CoNS (13/43) and Staphylococcus aureus (22/43) made up the majority. The most prevalent of the five Gram-negative bacteria was Pseudomonas aeruginosa. Results of drug sensitivity tests indicate that S. aureus is highly sensitive to vancomycin, cotrimoxazole, and linezolid, whereas CoNS is highly sensitive to vancomycin, linezolid, and chloramphenicol. Both of these bacteria show high resistance to erythromycin and penicillin. Breast augmentation, breast reconstruction, and breast reduction surgery were the most frequently associated breast surgery procedures in this study with infections, with the highest number of infections occurring following breast augmentation with fat grafting, breast reduction surgery, and breast reconstruction with autologous tissue. Various breast plastic surgery procedures have different common pathogens of infection, but the most prevalent are CoNS and S. aureus. Additionally, the majority of the infections in this study were in the early stages.

CONCLUSIONS

Gram-positive bacteria were the predominant cause of breast plastic surgery infections, and the types of infection strains, the period of infection onset, and the antibiotic susceptibility of prevalent strains varied between breast plastic procedures.

Injectable systems of chitosan in situ forming composite gel incorporating linezolid-loaded biodegradable nanoparticles for long-term treatment of bone infections

The objective of the current study was to create an efficient, minimally invasive combined system comprising in situ forming hydrogel loaded with both spray-dried polymeric nanoparticles encapsulating linezolid and nanohydroxyapatite for local injection to bones or their close vicinity. The developed system was designed for a dual function namely releasing the drug in a sustained manner for long-term treatment of bone infections and supporting bone proliferation and new tissues generation. To achieve these objectives, two release sustainment systems for linezolid were optimized namely a composite in situ forming chitosan hydrogel and spray-dried PLGA/PLA solid nanoparticles. The composite, in situ forming hydrogel of chitosan was prepared using two different gelling agents namely glycerophosphate (GP) and sodium bicarbonate (NaHCO3) at 3 different concentrations each. The spray-dried linezolid-loaded PLGA/PLA nanoparticles were developed using a water-soluble carrier (PVP K30) and a lipid soluble one (cetyl alcohol) along with 3 types of DL-lactide and/or DL-lactide-co-glycolide copolymer using nano-spray-drying technique. Finally, the optimized spray-dried linezolid nanoparticles were incorporated into the optimized composite hydrogel containing nanohydroxy apatite (nHA). The combined hydrogel/nanoparticle systems displayed reasonable injectability with excellent gelation time at 37 °C. The optimum formulae sustained the release of linezolid for 7-10 days, which reveals its ability to reduce the frequency of injection during the course of treatment of bones infections and increase the patients' compliance. They succeeded to alleviate the bone infections and the associated clinical, biochemical, radiological, and histopathological changes within 2-4 weeks of injection. As to the state of art in this study and to the best of our knowledge, no such complete and systematic study on this type of combined in situ forming hydrogel loaded with spray-dried nanoparticles of linezolid is available yet in literatures.

Systematic review of ceftaroline fosamil in the management of patients with methicillin-resistant Staphylococcus aureus pneumonia

Methicillin-resistant Staphylococcus aureus (MRSA) is responsible for an array of problematic community- and healthcare-acquired infections, including pneumonia, and is frequently associated with severe disease and high mortality rates. Standard recommended treatments for empiric and targeted coverage of suspected MRSA in patients with community-acquired pneumonia (CAP) and hospital-acquired pneumonia (HAP), including ventilator-associated pneumonia (VAP), are vancomycin and linezolid. However, adverse events such as acute kidney injury and Clostridium difficile infection have been associated with these antibiotics. Ceftaroline fosamil is a β-lactam/extended-spectrum cephalosporin approved for the treatment of adults and children with CAP and complicated skin and soft tissue infections. Ceftaroline has in vitro activity against a range of common Gram-positive bacteria and is distinct among the β-lactams in retaining activity against MRSA. Due to the design of the pivotal randomised controlled trials of ceftaroline fosamil, outcomes in patients with MRSA CAP were not evaluated. However, various reports of real-world outcomes with ceftaroline fosamil for pneumonia caused by MRSA, including CAP and HAP/VAP, been published since its approval. A systematic literature review and qualitative analysis of relevant publications was undertaken to collate and summarise relevant published data on the efficacy and safety of ceftaroline fosamil in patients with MRSA pneumonia. While relatively few real-world outcomes studies are available, the available data suggest that ceftaroline fosamil is a possible alternative to linezolid and vancomycin for MRSA pneumonia. Specific scenarios in which ceftaroline fosamil might be considered include bacteraemia and complicating factors such as empyema.

A mucoadhesive nanolipo gel containing Aegle marmelos gum to enhance transdermal effectiveness of linezolid for vaginal infection: In vitro evaluation, in vitro-ex vivo correlation, pharmacokinetic studies

Effective treatment of vaginal infections with conventional antibiotics often faces challenges like unavoidable dose-related side effects with increased risk of bacterial resistance. The study aims to deliver linezolid through natural gum based mucoadhesive nano lipogel to improve therapeutic effectiveness against vaginal infections. The linezolid loaded nanoliposomes (LNLs) were developed by thin film hydration method and were characterized by FTIR, DSC, XRD, FESEM, particle size analysis, zeta potential, drug loading capacity, in vitro release study etc. Selected LNLs was loaded into suitable gel formulation containing Aegle marmelos gum (as the mucoadhesive agent) and evaluated for in vitro, in vivo potentiality. FTIR/DSC test confirmed absence of any major interaction between selected drug and excipients. XRD showed amorphization of the drug encapsulated in NLs. FESEM studies showed spherical LNLs having smooth surface. LNLs had nanosize (51.03 nm), negative surface charge (-25.7 mV), satisfied drug loading capacity (11.5 ± 0.7 %) with sustained drug release. The experimental LNLs loaded lipogel showed desired physico-chemical properties viz. viscosity (37000 cps), spreadability (6.5 gm.cmsec-1), mucoadhesion (21.9 gf) and 61.04 % release of drug across rabbit vaginal mucosal membrane. The nanolipo gel exhibited improved antimicrobial activity against E. coli and C. albicans with respect to the pure linezolid. A good correlation was observed in between in vitro drug release and ex vivo permeation. Improved pharmacokinetic parameters like AUC, AUMC, MRT, Vd was observed for experimental nanolipo gel Vs. marketed formulation. The experimental nanolipo gel could be explored further for futuristic clinical application.

Indocyanine green clearance test as a predictor of linezolid overexposure in septic patients

OBJECTIVES

Hepatic impairment increases the risk of drug overexposure in septic patients. However, there is a lack of effective indicators to predict overexposure risk. The indocyanine green (ICG) clearance test is a helpful method for dynamically assessing hepatic function and perfusion. This study aimed to investigate whether the ICG test could serve as a potential predictor of linezolid trough concentration (Cmin) and to compare its efficacy with that of conventional liver function markers.

METHODS

A total of 35 consecutive septic patients treated with linezolid were grouped into either linezolid Cmin of ≤7 µg/mL or >7 µg/mL. Correlations between linezolid Cmin and ICG-PDR (plasma disappearance rate), ICG-R15 (retention ratio after 15 min) and other traditional indicators were analysed by Spearman's rank test. A multivariable regression model was employed to discern factors contributing independently to overexposure.

RESULTS

Statistical differences were observed between groups for APACHE II score (P = 0.031), SOFA score (P = 0.018), creatinine clearance (CLCr) (P = 0.003), thrombocytes (P = 0.039), lactate (P = 0.003), ICG-PDR (P < 0.001) and ICG-R15 (P < 0.001). Moreover, linezolid Cmin was correlated with ICG-PDR (ρ = -0.628, P < 0.001), ICG-R15 (ρ = 0.676, P < 0.001) and CLCr (ρ = -0.503, P = 0.002). ICG-PDR was identified as an independent predictor of linezolid overexposure, with an optimal cut-off value of 17.70%/min (93.3% sensitivity, 85.0% specificity; P < 0.001).

CONCLUSIONS

This pilot clinical trial represents the first investigation of potential of the ICG test to predict linezolid overexposure in septic patients.

Protein binding investigation of first-line and second-line antituberculosis drugs

Data on protein binding are incomplete for first-line antituberculosis drugs, and lacking for second-line antituberculosis drugs that are used extensively for multi-drug-resistant tuberculosis (levofloxacin, linezolid and moxifloxacin). Thus, the main purposes of this study were to investigate: (i) the relationship between carrier protein concentration and drug binding; and (ii) the feasibility of predicting free drug concentration using in-vitro and in-vivo results. In-vitro experiments were performed on spiked plasma mimicking real-case samples (drug combinations from clinical practice). Median in-vivo protein binding was 1.5% for ethambutol, 9.7% for isoniazid, 0.7% for pyrazinamide and 88.2% for rifampicin; and median in-vitro protein binding was 26.2% for levofloxacin, 12.8% for linezolid and 46.3% for moxifloxacin. Albumin concentration (<30 g/L) had a moderate impact on moxifloxacin binding and a strong impact on levofloxacin, linezolid and rifampicin binding. Determination of the free drug concentration seems to be of little value for ethambutol, isoniazid, moxifloxacin and pyrazinamide; limited value for linezolid because of its low binding; and major value for rifampicin in hypoalbuminaemic patients with tuberculosis, and levofloxacin because total concentration was an inaccurate reflection of free concentration. The free concentration predicted by the mathematical model was suitable for levofloxacin and linezolid, whereas the real free concentration should be measured for rifampicin. Further investigations should be carried out to investigate the benefit of using free concentration for levofloxacin, linezolid and rifampicin, particularly in the critical period of active tuberculosis associated with hypoalbuminaemia.

Rifampicin reduces plasma concentration of linezolid in patients with infective endocarditis

BACKGROUND

Linezolid in combination with rifampicin has been used in treatment of infective endocarditis especially for patients infected with staphylococci.

OBJECTIVES

Because rifampicin has been reported to reduce the plasma concentration of linezolid, the present study aimed to characterize the population pharmacokinetics of linezolid for the purpose of quantifying an effect of rifampicin cotreatment. In addition, the possibility of compensation by dosage adjustments was evaluated.

PATIENTS AND METHODS

Pharmacokinetic measurements were performed in 62 patients treated with linezolid for left-sided infective endocarditis in the Partial Oral Endocarditis Treatment (POET) trial. Fifteen patients were cotreated with rifampicin. A total of 437 linezolid plasma concentrations were obtained. The pharmacokinetic data were adequately described by a one-compartment model with first-order absorption and first-order elimination.

RESULTS

We demonstrated a substantial increase of linezolid clearance by 150% (95% CI: 78%-251%), when combined with rifampicin. The final model was evaluated by goodness-of-fit plots showing an acceptable fit, and a visual predictive check validated the model. Model-based dosing simulations showed that rifampicin cotreatment decreased the PTA of linezolid from 94.3% to 34.9% and from 52.7% to 3.5% for MICs of 2 mg/L and 4 mg/L, respectively.

CONCLUSIONS

A substantial interaction between linezolid and rifampicin was detected in patients with infective endocarditis, and the interaction was stronger than previously reported. Model-based simulations showed that increasing the linezolid dose might compensate without increasing the risk of adverse effects to the same degree.

Optimizing the formulation variables for encapsulation of linezolid into polycaprolactone inhalable microspheres using double emulsion solvent evaporation

Inhaled antibiotics delivered through dry powder inhalers (DPIs) effectively treat severe bacterial infections by directly targeting the lungs. Our study focused on developing inhalable dry powder microspheres of linezolid (LNZ) using biodegradable polycaprolactone (PCL) polymer. The LNZ-PCL microspheres were fabricated using a double emulsification solvent evaporation method. Optimization of formulation parameters was performed using a factorial design. Evaluation of the microspheres included size, shape, drug loading, entrapment efficiency, aerosolization, and drug release. The morphological analysis confirmed spherical-shaped rough particles within the inhalable size range. The encapsulation efficiency was determined to be 52.84%, indicating successful drug incorporation. Aerosolization efficiency was significantly enhanced when LNZ-PCL microspheres were combined with lactose as a carrier, achieving a fine particle fraction (FPF) value of 70.90%. In-vitro dissolution studies demonstrated sustained drug release for over 24 h under lung pH conditions. Overall, our study highlights the potential of inhalable LNZ-PCL microspheres as a targeted approach for treating pulmonary tuberculosis. Further research and in-vivo studies are needed to validate their effectiveness in life-threatening bacterial infections.

Australian Group on Antimicrobial Resistance (AGAR) Australian Enterococcal Surveillance Outcome Program (AESOP) Bloodstream Infection Annual Report 2022

From 1 January to 31 December 2022, fifty-five institutions across Australia participated in the Australian Enterococcal Surveillance Outcome Program (AESOP). The aim of AESOP 2022 was to determine the proportion of enterococcal bacteraemia isolates in Australia that were antimicrobial resistant, and to characterise the molecular epidemiology of the Enterococcus faecium isolates. Of the 1,535 unique episodes of enterococcal bacteraemia investigated, 92.8% were caused by either E. faecalis (52.9%) or E. faecium (39.9%). Ampicillin and vancomycin resistance were not detected in E. faecalis but were detected in 95.4% and 46.9% of E. faecium respectively. One E. faecalis isolate, with a daptomycin minimum inhibitory concentration (MIC) of 8.0 mg/L, harboured the F478L GdpD mutation. One E. faecium with a daptomycin MIC of 24.0 mg/L harboured the A20D Cls mutation; both mutations are known to be associated with daptomycin resistance. Two E. faecium isolates, one with a linezolid MIC ≥ 256 mg/L and the other with a linezolid MIC of 16 mg/L, harboured the 23S rRNA G2576T mutation, a mutation associated with linezolid resistance in enterococci. Overall, 48.8% of E. faecium harboured either the vanA or the vanB gene, of which 28.0% harboured vanA and 72.0% harboured vanB. The percentage of vancomycin-resistant E. faecium bacteraemia isolates in Australia remains substantially higher than that recorded in most European countries. The E. faecium isolates consisted of 62 multi-locus sequence types (STs); 85.5% of isolates were classified into eight major STs each containing ten or more isolates. All major STs belonged to clonal complex (CC) 17, a major hospital-adapted polyclonal E. faecium cluster. The major STs (ST17, ST78, ST80, ST117, ST555, ST796, ST1421, and ST1424) were each found across most regions of Australia. The predominant ST was ST17, which was identified in all regions. Overall, 53.7% of isolates belonging to the eight major STs harboured the vanA or vanB gene. AESOP 2022 has shown that enterococcal bacteraemia episodes in Australia are frequently caused by polyclonal ampicillin-resistant high-level gentamicin resistant vanA- or vanB-positive E. faecium which have limited treatment options.

Therapeutic drug monitoring of linezolid: HPLC-based assays for routine quantification of linezolid in human serum and cerebrospinal fluid

OBJECTIVE

Therapeutic drug monitoring (TDM) of linezolid can prevent over- and under-dosing in critically ill patients and can be crucial to successful antibiotic treatment. Quick and simple high-performance liquid chromatography (HPLC) assays for the detection of linezolid in human serum and cerebrospinal fluid (CSF) were developed in this study.

METHODS

The methods used an Atlantis T3 5.0 µm stationary phase. The mobile phase A contained water (99.4% m/m) and formic acid (0.6% m/m) (pH 2.30). The mobile phase B contained acetonitrile (93.6% m/m), water (6% m/m) and formic acid (0.4% m/m). The methods were isocratic, using 23% of mobile phase B and 77% of mobile phase A. Ultraviolet absorbance detection at 252 nm was used. For sample preparation an internal standard was added, and acetonitrile/methanol was added for protein precipitation.

RESULTS

The methods were investigated for linearity, specificity, accuracy, and precision. Stability of linezolid and internal standard was assessed. The retention times of linezolid were 8.5 min and 8.1 min, and the single run time was 15 min. Linezolid was quantified from the lower limit of quantification (0.2 mg/L) to the upper limit of quantification (50 mg/L, 75 mg/L, and 100 mg/L). In routine analysis a high variability of serum and CSF levels was observed and the mean CSF/serum ratio was 0.71±0.16.

CONCLUSION

The developed assays enable the study of correlations between the applied dosage, serum concentration and CSF concentration. Additionally, studies with a higher number of samples can be performed to investigate the penetration of linezolid into the central nervous system.

99mTc-linezolid as a radiotracer for brain abscess: Labeling, in silico docking, and biodistribution studies

Brain abscess is a life-threatening condition that requires a timely and accurate diagnosis. In this study, linezolid, an oxazolidinone antibiotic, was labeled with technetium-99m according to the stannous chloride method. The labeling reaction factors were studied and optimized to achieve a high yield (97.4 ± 2.3%). The 99mTc-linezolid was radio- and physico-chemically characterized to assess its suitability as a radiopharmaceutical for the brain. In-silico docking to target peptidyltransferase showed an optimal binding fit (energy = -66.6 Kcal/mol). The complex was biologically evaluated in-vitro using binding assays in alive and heat-killed bacteria and in-vivo in an MRSA brain infection model. All results suggested that the labeled complex could potentially be a new nuclear imaging agent to diagnose and localize brain abscesses specifically.

Severe skin infections

PURPOSE OF REVIEW

The incidence of necrotizing soft-tissue infections (NSTI) has increased during recent decades. These infections are still associated with high morbidity and mortality, underlining a need for continued education of the medical community. This review will focus on practical approaches to management of NSTI focusing on antibiotic therapies and optimizing the management of group A streptococcus (GAS)-associated NSTIs.

RECENT FINDINGS

Antibiotic therapy for NSTI patients faces several challenges as the rapid progression of NSTIs mandates broad-spectrum agents with bactericidal action. Current recommendations support using clindamycin in combination with penicillin in case of GAS-documented NSTIs. Linezolide could be an alternative in case of clindamycin resistance.

SUMMARY

Reducing the time to diagnosis and first surgical debridement, initiating early broad-spectrum antibiotics and early referral to specialized centres are the key modifiable factors that may impact the prognosis of NSTIs. Causative organisms vary widely according to the topography of the infection, underlying conditions, and geographic location. Approximately one third of NSTIs are monomicrobial, involving mainly GAS or Staphylococcus aureus . Data for antibiotic treatment specifically for necrotizing soft-tissue infections are scarce, with guidelines mainly based on expert consensus.

Toxic neuropathies

PURPOSE OF REVIEW

Immunotherapy has had a significant impact on the treatment of an increasing number of cancers as well as in inflammatory, rheumatological and gastroenterological conditions.Recreational nitrous oxide use is now a global epidemic. Linezolid is now recommended for the treatment of drug-resistant tuberculosis (TB); neuropathy is a significant cause of morbidity.Global warming will result in increasing toxin exposure, such as ciguatera, in previously unaffected areas.

RECENT FINDINGS

With increasing experience, the pathophysiology underlying the neuropathic complications of these drugs has become clear with guidelines now available, for the complications of immune check-point inhibitors and nitrous oxide toxicity. The optimum dose and duration of treatment for resistant TB with regimens, including linezolid, has been ascertained.

SUMMARY

Although neuropathic complications with immunotherapy are relatively rare, it is essential that they are recognized and treated early. Nitrous oxide toxicity should be in the differential diagnosis for all patients, particularly those of younger age, presenting with a neuropathy or myleo-neuropathy. Ciguatera toxicity is under recognized and its geographical spread will increase due to global warming. Further research is necessary on the mechanisms and treatment of both acute and chronic effects, which at present, are only symptomatic.

Multidrug-resistant bacterial infection in adult patients following cardiac surgery: clinical characteristics and risk factors

BACKGROUND

The prevalence of infections with multidrug-resistant organism (MDRO) pose great challenges for anti-infective therapy. Previous research on MDRO infections after cardiac surgery was limited. Therefore, understanding and mastering the clinical characteristics and risk predictors of MDRO infection after cardiac surgery is of great significance for standardized management of perioperative patients.

METHODS

The medical records of adult patients with MDRO infection after cardiac surgery from January 2018 to October 2021 were collected, and patients were divided into MDR infection group (n = 176) and non-MDR infection group (n = 233). Univariate and multivariate regression analysis of variables was performed to determine the risk predictors of MDRO infection.

RESULTS

The incidence of MDRO infection was 8.6%. Acinetobacter baumannii, Klebsiella pneumoniae and Pseudomonas aeruginosa were the most common, accounting for 37.3%, 23.5% and 18.0%, respectively. The main infection type were lower respiratory tract infection (LTRI = 29.0%). Univariate analysis showed that underwent coronary artery bypass graft (CABG) (P = 0.001) and secondary operation (P = 0.008), pre-infection exposure to vancomycin (P < 0.001) and linezolid (P = 0.002), combination antibiotics (P < 0.001), four antibiotics in combination (P = 0.005), glucocorticoid use (P = 0.029), preoperative hypoalbuminemia (P = 0.003) were risk factors for post-operative MDRO infection. Multivariate regression analysis showed that underwent CABG (OR = 1.228, 95%CI = 1.056∽1.427, P = 0.008), secondary operation (OR = 1.910, 95%CI = 1.131∽3.425, P = 0.015) and pre-infection exposure to linezolid (OR = 3.704, 95%CI = 1.291∽10.629, P = 0.005) were independent risk predictors for MDRO infection. The risk of MDRO infection increased with the length of stay in the ICU (P < 0.001) and the length of stay before diagnosis of infection (P = 0.003), and the difference was statistically significant. Meanwhile, the length of stay after infection (P = 0.005) and the total length of hospital stay (P < 0.001) were significantly longer in the MDRO infection group, and the all-cause mortality was numerically higher in the MDRO infection group (31.3% versus 23.2%).

CONCLUSIONS

The morbidity and mortality of MDRO infection was high in adult cardiac surgery, and many risk factors influence the occurrence of MDRO infection. In the future, clinicians should focus on high-risk patients, strengthen multidisciplinary collaboration on infection prevention and control measures, reduce the morbidity and mortality of MDRO infection, and improve the prognosis of in-hospital patients.

A cost minimisation analysis comparing oral linezolid and intravenous daptomycin administered via an outpatient parenteral antibiotic therapy programme in patients requiring prolonged antibiotic courses

This study is an economic analysis seeking to examine cost savings that may be accrued from usage of oral linezolid in place of OPAT IV daptomycin in patients requiring prolonged courses of IV or highly bioavailable oral antibiotic therapy. In order to do so we conducted a literature review to establish the scenarios in which the agents could be considered equivalent. We then, using a decision-tree model, conducted a cost analysis to establish differences in cost between the approaches. Under the model base-case, the total cost of treatment with OPAT daptomycin was €3,496.84 and the total cost of treatment with oral linezolid was €772.01. Therefore the oral linezolid strategy would be projected to save the Irish health service €2,724.83 per patient. These results were robust to one-way deterministic sensitivity analyses and probabilistic sensitivity analysis. Our study suggests that significant savings could be safely accrued in the management of these patients.

Model-informed precision dosing of antimicrobial drugs in pediatrics: experiences from a pilot scale program

Antibiotics are among the most utilized drugs in pediatrics. Nonetheless, there is a lack in pharmacokinetics information for this population, and dosing criteria may vary between healthcare centers. Physiological variability associated with maturation in pediatrics makes it challenging to reach a consensus on adequate dosing, which is further accentuated in more vulnerable groups, such as critically ill or oncology patients. Model-informed precision dosing is a useful practice that allows dose optimization and attainment of antibiotic-specific pharmacokinetic/pharmacodynamic targets. The aim of this study was to evaluate the needs of model-informed precision dosing of antibiotics in a pediatrics unit, at a pilot scale. Pediatric patients under antibiotic treatment were monitored with either a pharmacokinetic/pharmacodynamic optimized sampling scheme or through opportunistic sampling. Clindamycin, fluconazole, linezolid, meropenem, metronidazole, piperacillin, and vancomycin plasma concentrations were quantified through a liquid chromatography coupled to mass spectrometry method. Pharmacokinetic parameters were estimated using a Bayesian approach to verify pharmacokinetic/pharmacodynamic target attainment. A total of 23 pediatric patients aged 2 to 16 years were included, and 43 dosing regimens were evaluated; 27 (63%) of them required adjustments as follows: 14 patients were underdosed, 4 were overdosed, and 9 patients needed infusion rate adjustments. Infusion rate adjustments were mostly recommended for piperacillin and meropenem; daily doses were augmented for vancomycin and metronidazole, meanwhile linezolid was adjusted for under- and overdosing. Clindamycin and fluconazole regimens were not adjusted at all.  Conclusion: Results showcase a lack of antibiotic pharmacokinetic/pharmacodynamic target attainment (particularly for linezolid, vancomycin, meropenem, and piperacillin), and the need for model-informed precision dosing in pediatrics. This study provides pharmacokinetic evidence which can further improve antibiotic dosing practices. What is Known: • Model-informed precision dosing is performed in pediatrics to optimize the treatment of antimicrobial drugs such as vancomycin and aminoglycosides, while its usefulness is debated for other groups (beta-lactams, macrolides, etc.). What is New: • Vulnerable pediatric subpopulations, such as critically ill or oncology patients, can benefit the most from model-informed precision dosing of antibiotics. • Model-informed precision dosing of linezolid, meropenem, piperacillin, and vancomycin is particularly useful in pediatrics, and further research may improve dosing practices altogether.

Cumulative antimicrobial susceptibilities for respiratory clinical isolates of Mycobacterium avium Complex, Mycobacterium kansasii, and Mycobacterium abscessus from Pakistan 2018 to 2022

Background

Nontuberculous mycobacteria (NTM) are increasingly identified as causes of protracted pulmonary infections. Antibiotic susceptibility testing requires microdilution methods, which are often unavailable in laboratories in resource-poor settings. We report cumulative antibiograms for the most frequently isolated clinical pulmonary NTM from Pakistan to inform empiric antibiotic management of initial NTM infections.

Methods

We analyzed data from 2018 to 2022 for the most frequently isolated and clinically relevant NTM isolated from respiratory specimens, i.e., Mycobacterium avium complex (MAC), Mycobacterium abscessus group (MAG), and Mycobacterium kansasii (MK). Antibiograms were developed using the Clinical Laboratory Standards Institute's M39ED5 standard. Percentage susceptibilities and 95% confidence intervals (CI) were calculated.

Results

Over 4 years, 529 NTM, comprising 209 MAC, 249 MAG, and 71 MK were analyzed. For MAC and MAG, where clarithromycin (CLR)-based regimens are recommended, CLR was active for 94.8% (95% CI 91.3-96.9), and 77.5% (95% CI 71.4-82.7) isolates, respectively. Combination regimens comprising 3 active drugs CLR + linezolid (LZD) + moxifloxacin for MAC and CLR + LZD + Amikacin for MAG had 98.4% (95% CI 95.9-99.4) and 68.9% (95% CI 62.3-74.8) coverage for pulmonary disease, respectively. For MK, 91.5% (95% CI 82.8-96.1) isolates were susceptible to rifampin (RIF), with a combination of RIF + CLR covering 88.7% (95% CI 79.3-94.2) of MK pulmonary infections, respectively.

Conclusions

These data can inform empiric treatment guidance for the most common NTM pulmonary infections, i.e., for MAC, MAG, and MK disease in Pakistan.

Subspecies Distribution and Antimicrobial Susceptibility Testing of Mycobacterium abscessus Clinical Isolates in Madrid, Spain: a Retrospective Multicenter Study

Mycobacterium abscessus (MABS) is the most pathogenic and drug-resistant rapidly growing mycobacteria. However, studies on MABS epidemiology, especially those focusing on subspecies level, are scarce. We aimed to determine MABS subspecies distribution and its correlation with phenotypic and genotypic antibiotic profiles. A retrospective multicenter study of 96 clinical MABS isolates in Madrid between 2016 to 2021 was conducted. Identification at the subspecies level and resistance to macrolides and aminoglycosides were performed by the GenoType NTM-DR assay. The MICs of 11 antimicrobials tested against MABS isolates were determined using the broth microdilution method (RAPMYCOI Sensititer titration plates). Clinical isolates included 50 (52.1%) MABS subsp. abscessus; 33 (34.4%) MABS subsp. massiliense; and 13 (13.5%) MABS subsp. bolletii. The lowest resistance rates corresponded to amikacin (2.1%), linezolid (6.3%), cefoxitin (7.3%), and imipenem (14.6%), and the highest to doxycycline (100.0%), ciprofloxacin (89.6%), moxifloxacin (82.3%), cotrimoxazole (82.3%), tobramycin (81.3%), and clarithromycin (50.0% at day 14 of incubation). Regarding tigecycline, although there are no susceptibility breakpoints, all strains but one showed MICs ≤ 1 μg/mL. Four isolates harbored mutations at positions 2058/9 of the rrl gene, one strain harbored a mutation at position 1408 of the rrl gene, and 18/50 harbored the T28C substitution at erm(41) gene. Agreement of the GenoType results with clarithromycin and amikacin susceptibility testing was 99.0% (95/96). The rate of MABS isolates showed an upward trend during the study period, being M. abscessus subsp. abscessus the most frequently isolated subspecies. Amikacin, cefoxitin, linezolid, and imipenem showed great in vitro activity. The GenoType NTM-DR assay provides a reliable and complementary tool to broth microdilution for drug resistance detection. IMPORTANCE Infections caused by Mycobacterium abscessus (MABS) are increasingly being reported worldwide. Identifying MABS subspecies and assessing their phenotypic resistance profiles are crucial for optimal management and better patient outcomes. M. abscessus subspecies differ in erm(41) gene functionality, which is a critical determinant of macrolide resistance. Additionally, resistance profiles of MABS and the subspecies distribution can vary geographically, highlighting the importance of understanding local epidemiology and resistance patterns. This study provides valuable insights into the epidemiology and resistance patterns of MABS and its subspecies in Madrid. Elevated resistance rates were observed for several recommended antimicrobials, emphasizing the need for cautious drug use. Furthermore, we assessed the GenoType NTM-DR assay, which examines principal mutations in macrolides and aminoglycosides resistance-related genes. We observed a high level of agreement between the GenoType NTM-DR assay and the microdilution method, indicating its usefulness as an initial tool for early initiation of appropriate therapy.

Surveillance and analysis of bacterial resistance in a comprehensive teaching hospital from 2015 to 2017

To understand the changes of resistance of major clinical isolates to commonly used antibiotics in a comprehensive teaching hospital from 2015 to 2017 and to provide a basis for rational clinical use of antibiotics in the hospital. Antimicrobial susceptibility testing of all clinical isolates from 2015 to 2017 was carried out according to a unified protocol using Kirby-Bauer method or automated systems according to the unified plan. A total of 28715 non-repetitive clinical isolates were collected from 2015 to 2017. Escherichia coli, Klebsiella pneumoniae and Acinetobacter baumannii were the top three most common isolates for three consecutive years. Escherichia coli is still highly sensitive to carbapenems, with the drug resistance rate less than 1%. Klebsiella pneumoniae's resistance to carbapenems increases year by year, reaching about 18% in 2017. The resistance rate of Acinetobacter baumannii to meropenem was above 70%, and that of Pseudomonas aeruginosa to meropenem was about 30%. Staphylococcus is more sensitive to linezolid and vancomycin. Enterococcus faecalis had lower drug resistance to most tested antibiotics (except tetracycline) than Enterococcus faecalis, and both were sensitive to linezolid and vancomycin. Bacterial resistance to commonly used antibiotics is still on the rise. We should strengthen the management of clinical use of antimicrobial agents and maintain good practice in surveillance of bacterial resistance.

Efficacy of Omadacycline-Containing Regimen in a Mouse Model of Pulmonary Mycobacteroides abscessus Disease

Mycobacteroides abscessus is an opportunistic pathogen in people with structural lung conditions such as bronchiectasis, chronic obstructive pulmonary disease, and cystic fibrosis. Pulmonary M. abscessus infection causes progressive symptomatic and functional decline as well as diminished lung function and is often incurable with existing antibiotics. We investigated the efficacy of a new tetracycline, omadacycline, in combination with existing antibiotics recommended to treat this indication, in a mouse model of M. abscessus lung disease. Amikacin, azithromycin, bedaquiline, biapenem, cefoxitin, clofazimine, imipenem, linezolid, and rifabutin were selected as companions to omadacycline. M. abscessus burden in the lungs of mice over a 4-week treatment duration was considered the endpoint. Omadacycline in combination with linezolid, imipenem, cefoxitin, biapenem, or rifabutin exhibited early bactericidal activity compared to any single drug. Using three M. abscessus isolates, we also determined the in vitro frequency of spontaneous resistance against omadacycline to be between 1.9 × 10-10 and 6.2 × 10-10 and the frequency of persistence against omadacycline to be between 5.3 × 10-6 and 1.3 × 10-5. Based on these findings, the combination of omadacycline and select drugs that are included in the recent treatment guidelines may exhibit improved potency to treat M. abscessus lung disease. IMPORTANCE M. abscessus disease incidence is increasing in the United States. This disease is difficult to cure with existing antibiotics. In this study, we describe the efficacy of a new tetracycline antibiotic, omadacycline, in combination with an existing antibiotic to treat this disease. A mouse model of M. abscessus lung disease was used to assess the efficacies of these experimental treatment regimens. Omadacycline in combination with select existing antibiotics exhibited bactericidal activity during the early phase of treatment.

A 12-Year Retrospective Analysis of Blood Culture Isolates in the Intensive Care Unit of a Tertiary Hospital in China

BACKGROUND

This paper is to explore the composition and antibiotic resistance of pathogens isolated from blood cultures of patients with bloodstream infection (BSI) in the intensive care unit (ICU).

METHODS

A retrospective study has been performed to identify the pathogens isolated from blood cultures of 147 patients with BSI in the ICU of our Hospital over 12 years (January 2008 to December 2019). The antibiotic resistance and susceptibility of the isolates were tested.

RESULTS

Among the 152 pathogens isolated from positive blood cultures, 61.84% were Gram-positive bacteria, 34.87% were Gram-negative bacteria, and 3.29% were fungi. The most frequently isolated pathogens were coagulase-negative Staphylococci, Staphylococcus aureus, and Escherichia coli. The pathogen distributions remained stable over 12 years. Gram-positive cocci were highly susceptible to vancomycin, linezolid, and teicoplanin. Extended-spectrum β-lactamase-producing pathogens were highly susceptible to amikacin, imipenem, meropenem, and polymyxin B. Acinetobacter were relatively sensitive to amikacin, trimethoprim-sulfamethoxazole, and polymyxin, whereas Pseudomonas aeruginosa were sensitive to amikacin, gentamicin, levofloxacin, imipenem, meropenem, and ciprofloxacin, with resistance rates less than 30%.

CONCLUSIONS

Gram-positive bacteria were the dominant pathogens isolated from blood cultures of ICU-BSI patients and were susceptible to vancomycin, linezolid, and teicoplanin. The antibiotic susceptibility of Gram-negative bacteria varies greatly. Our results provide important information to guide the treatment decisions in the management of ICU-BSIs.

An Optimized Screening Approach for the Oxazolidinone Resistance Gene optrA Yielded a Higher Fecal Carriage Rate among Healthy Individuals in Hangzhou, China

The linezolid resistance mediated by optrA has exhibited an increasing trend among Gram-positive bacteria, which greatly limits the treatment options for severe bacterial infections. However, the prevalence of optrA was usually underestimated based on the existing screening methods. In this study, we used a traditional method and an improved method that included a high-salinity condition treatment after enrichment to screen for optrA-carrying bacteria from stool samples from 1,018 healthy donors in Hangzhou, China. The fecal carriage rate of optrA-carrying bacteria was 19.25% when screened by the improved method (196/1,018), which was much higher than that of the traditional method at 5.89% (60/1,018). Enterococci were the majority of the optrA-positive isolates, while five nonenterococcal isolates were also obtained, including two Streptococcus gallolyticus, one Vagococcus lutrae, one Lactococcus garvieae, and one Lactococcus formosensis isolate. Whole-genome sequencing analysis identified four novel OptrA variants, IDKKGPM, IDKKGP, KLDK, and EYDDI, in these isolates, whose optrA-flanking regions with a fexA gene downstream were bounded by different insertion sequences. In conclusion, our optimized method displayed high sensitivity in the detection of optrA-positive bacteria in fecal samples and revealed a high carriage rate in a healthy population. Although enterococci are dominant, multiple optrA-carrying Gram-positive bacteria were also found. IMPORTANCE This study represented an optimized screening approach for the optrA gene, which is an important mechanism of antimicrobial resistance to linezolid as a last resort for the treatment of infections caused by multiresistant Gram-positive bacteria. We revealed a high fecal carriage rate of the optrA gene among adults by this method and reported the first identification of optrA in Lactococcus formosensis as well as the identification of this gene in Vagococcus lutrae and of the poxtA gene in Ligilactobacillus salivarius of human origin, suggesting the wide spread of the optrA gene in the Gram-positive bacterial community.

[Application of initial anti-infectives and trends in children with septic shock]

Objective: To investigate the pathogen composition, initial anti-infectives and pathogen coverage, and trends over the last 5 years in children with septic shock in pediatric intensive care unit (PICU). Methods: The single-center retrospective study included 257 children with septic shock who were admitted to PICU of Beijing Children's Hospital, Capital Medical University from 2017 to 2021. The causitive pathogen composition, initial use of anti-infective drugs, pathogen coverage, and changes in recent years were analyzed. The children were divided into sufficient and insufficient coverage groups according to whether the pathogen were sufficiently covered by initial anti-infectives; community-and hospital-acquired groups; and with and without underlying disease groups. T test, rank-sum test and Chi-square test were used for comparison between the groups to investigate the differences in pathogen, treatment and prognosis. Results: A total of 257 septic shock children were included, with 162 males and 95 females, aged 36 (12, 117) months. The pathogen positive rate was 64.6% (166/257) and the in-hospital mortality was 27.6% (71/257). In the 208 pathogen-positive samples, bacteria was the most common (57.7%, 120/208) with G-negative bacteria predominating (55.8%, 67/120), followed by viruses (26.0%, 54/208). Nearly 99.2% (255/257) of the children were treated with antibacterial at the beginning, of whom 47.1% (121/257) were treated with carbapenems combined with vancomycin or linezolid. The proportion of 3 or more antibacterial combinations was higher in children with underlying diseases and hospital-acquired septic shock than in those without underlying disease or community-acquired septic shock (27.4% (49/179) vs. 14.1% (11/78), 29.4% (52/177) vs. 10.0% (8/80), χ²=5.35,11.56,all P<0.05). The proportion of initial combination of carbapenem and vancomycin or linezolid reduced from 52.5% (21/40) to 41.3% (19/46), and of adequate pathogen coverage increased from 40.0% (16/40) to 58.7% (27/46) in the last five years. Conclusions: The initial use of antibacterial drugs is common in children with septic shock in PICU, especially in those with hospital-acquired septic shock and underlying diseases. In recent years, antimicrobial combinations have decreased, but the pathogen coverage has improved, indicating that drug selection is more reasonable and accurate.

Epidemiology and in vitro antimicrobial susceptibility of aerobic Actinomycetales in a clinical setting

INTRODUCTION

The incidence of infections caused by aerobic actinomycetes is increasing. Recent changes in taxonomy and the variability in susceptibility patterns among species make necessary a proper identification and antibiotic susceptibility testing.

MATERIAL AND METHODS

Fifty-three strains of aerobic actinomycetes were identified by MALDI-TOF MS using the VITEK MS Mycobacterium/Nocardia kit (bioMérieux, France) in a tertiary hospital in Spain during a six-year period. Antimicrobial susceptibility testing of the isolates was performed using the Sensititre Rapmycoi microdilution panel (Thermo Fisher Scientific, Massachusetts, USA).

RESULTS

Forty strains of Nocardia spp. were identified in the study, being N. farcinica and N. cyriacigeorgica the most prevalent ones. All isolates were susceptible to linezolid and the resistance to amikacin was only observed in one isolate of Gordonia sputi. Resistance to cotrimoxazole was only found in five isolates.

CONCLUSIONS

Routine identification and antimicrobial susceptibility testing of aerobic actinomycetes is advisable for an efficient identification of species and effective treatment.

Association of Linezolid With Risk of Serotonin Syndrome in Patients Receiving Antidepressants

IMPORTANCE

Linezolid has the potential to interact with some antidepressants, leading to serotonin syndrome. However, few empirical data support warnings for patients taking antidepressants to avoid linezolid.

OBJECTIVES

To examine the incidence of serotonin syndrome in patients receiving oral linezolid and how concomitant antidepressant treatment changes this risk.

DESIGN, SETTING, AND PARTICIPANTS

This population-based, retrospective cohort study used linked administrative databases at ICES to collect data from outpatients 66 years or older in Ontario, Canada, who were prescribed oral linezolid for any duration from October 1, 2014, to January 1, 2021, with follow-up to 30 days (January 31, 2021).

EXPOSURES

The use of antidepressants while receiving linezolid therapy vs no antidepressant use while receiving linezolid therapy.

MAIN OUTCOMES AND MEASURES

The primary outcome was clinically significant serotonin syndrome based on a physician diagnosis, Sternbach criteria, or the Hunter Serotonin Toxicity Criteria within 30 days of starting oral linezolid treatment. Secondary outcomes were altered mental status, hospitalization, or death within 30 days of starting linezolid treatment.

RESULTS

The study included 1134 patients (age ranges, 66-69 years for 225 patients [19.8%], 70-79 years for 473 patients [41.7%], and ≥80 years for 436 patients [38.4%]; 595 [52.5%] male) who were prescribed linezolid. Of 1134 patients, 215 (19.0%) were also taking antidepressants. Serotonin syndrome occurred in fewer than 6 patients (<0.5%). The number of serotonin syndrome cases were fewer in the antidepressant group. In a propensity score-matched cohort, the adjusted risk difference for serotonin syndrome between the antidepressant group and the no antidepressant group was -1.2% (95% CI, -2.9% to 0.5%). There were similar rates of altered mental status, hospitalization, and death between the propensity score-matched groups.

CONCLUSIONS AND RELEVANCE

In this cohort study of older patients who were prescribed linezolid, serotonin syndrome occurred rarely. Concurrent antidepressants did not significantly increase the risk of serotonin syndrome. These findings suggested that linezolid is likely safe for patients receiving antidepressants. Nevertheless, prescribers should remain vigilant for this potential drug interaction.

New Drugs and Regimens for Tuberculosis Disease Treatment in Children and Adolescents

After almost 30 years of relative stagnation, research over the past decade has led to remarkable advances in the treatment of both drug-susceptible (DS) and drug-resistant (DR) tuberculosis (TB) disease in children and adolescents. Compared with the previous standard therapy of at least 6 months, 2 new regimens lasting for only 4 months for the treatment of DS-TB have been studied and are recommended by the World Health Organization (WHO), along with a shortened 6-month regimen for treatment of DS-TB meningitis. In addition, the 18- to 24-month regimens previously used for DR-TB that included painful injectable drugs with high rates of adverse effects have been replaced with shorter, safer all-oral regimens. Advances that have improved treatment include development of new TB drugs (bedaquiline, delamanid, pretomanid), reapplication of older TB drugs (rifampicin and rifapentine), and repurposing of other drugs (clofazimine and linezolid). The development of child-friendly formulations for many of these drugs has further enhanced the ability to safely and effectively treat DS- and DR-TB in children and adolescents. The characteristics and use of these drugs, regimens, and formulations are reviewed.

Narrowing down the conformational space with solid-state NMR in crystal structure prediction of linezolid cocrystals

Many solids crystallize as microcrystalline powders, thus precluding the application of single crystal X-Ray diffraction in structural elucidation. In such cases, a joint use of high-resolution solid-state NMR and crystal structure prediction (CSP) calculations can be successful. However, for molecules showing significant conformational freedom, the CSP-NMR protocol can meet serious obstacles, including ambiguities in NMR signal assignment and too wide conformational search space to be covered by computational methods in reasonable time. Here, we demonstrate a possible way of avoiding these obstacles and making as much use of the two methods as possible in difficult circumstances. In a simple case, our experiments led to crystal structure elucidation of a cocrystal of linezolid (LIN), a wide-range antibiotic, with 2,3-dihydroxybenzoic acid, while a significantly more challenging case of a cocrystal of LIN with 2,4-dihydroxybenzoic acid led to the identification of the most probable conformations of LIN inside the crystal. Having four rotatable bonds, some of which can assume many discreet values, LIN molecule poses a challenge in establishing its conformation in a solid phase. In our work, a set of 27 conformations were used in CSP calculations to yield model crystal structures to be examined against experimental solid-state NMR data, leading to a reliable identification of the most probable molecular arrangements.

Exposure to World Health Organization's AWaRe antibiotics and isolation of multidrug resistant bacteria: a systematic review and meta-analysis

BACKGROUND

Antibiotic use drives antibiotic resistance.

OBJECTIVES

To systematically review the literature and estimate associations between prior exposure to antibiotics across World Health Organization's (WHO) AWaRe categories (Access, Watch, Reserve) and isolation of critical and high-priority multidrug resistant organisms (MDROs) on the WHO priority pathogen list.

DATA SOURCES

Embase, Ovid Medline, Scopus, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov (from inception to 20/08/2020).

STUDY ELIGIBILITY CRITERIA

Case-control, cohort, or experimental studies that assessed the risk of infection/colonization with MDROs.

PARTICIPANTS

Inpatients or outpatients of any age and sex.

INTERVENTIONS

Prior exposure to antibiotics that could be categorized into the AWaRe framework.

DATA ANALYSIS

Tailored design-specific checklists applied to each included study. For each antibiotic/class, crude odds ratios (ORs) were pooled through random-effects meta-analyses, both overall and by MDRO. Heterogeneity was examined.

RESULTS

We identified 349 eligible studies. All were observational, prone to bias due to design and lack of adjustment for confounding, and not primarily designed to compare associations across AWaRe categories. We found statistically significant associations between prior exposure to almost all antibiotics/classes across AWaRe categories and colonization/infection with any MDRO. We observed higher ORs for Watch and Reserve antibiotics than with Access antibiotics. First generation cephalosporins (Access) had the least association with any MDRO colonization/infection (58 studies; OR = 1.2 [95% CI: 1.0-1.4]), whereas strongest associations were estimated for linezolid (Reserve) (22 studies; OR = 2.6 [95% CI: 2.1-3.1]), followed by carbapenems (Watch) (237 studies; OR = 2.3 [95% CI: 2.1-2.5]). There was high heterogeneity for all antibiotic/MDRO associations.

CONCLUSIONS

Optimising use of Access antibiotics is likely to reduce the selection of MDROs and global antibiotic resistance. Despite data limitations, our study offers a strong rationale for further adoption of AWaRe as an important tool to improve antibiotic use globally.

Antibiotic resistance rates and penicillin MIC distribution in patients with streptococcal pneumonia between 2013-2019, and use of antibiotics in clinical practice

PURPOSE

The purpose of the present study is to investigate the antibiotic resistance rates and use of antibiotics in patients with streptococcal pneumonia in a reference tertiary care hospital for pulmonary diseases in Izmir, Turkey.

METHODS

A total of 1224 cases with streptococcal pneumonia between 2013 and 2019 were included in the study, retrospectively. Drug susceptibility testing for penicillin and other antibiotics were performed according to the recommendations of EUCAST criteria. Clinical data and general characteristics were collected and evaluated for each patient in accordance with the susceptibility testing report.

RESULTS

Totally, resistance rates for trimethophrim-sulfamethoxazole, penicillin (oxacillin), erythromycin, tetracycline, clindamycin and levofloxacin resistance were 63.5%, 39.8%, 37.7%, 37.6%, 28.8%, and 4.8%, respectively. Antibiotic resistance was not detected against vancomycin,teicoplanin and linezolid. Multidrug resistance rate was found to be 27.1%. It was observed that there was a statistically significant decrease in trimethophrim-sulfamethoxazole, penicillin (oxacillin), erythromycin, clindamycin and levofloxacin resistance rates by years (p: 0.000, 0.004, 0.000, 0.001, 0.010, respectively). The penicillin MIC distribution was higher at the range of 0.12-2 ​μg/mL and there was statistical difference among the ranges of MIC values for the representative years (p:0.033). Among the antibiotics investigated, the most commonly used antibiotic was moxifloxacin.

CONCLUSIONS

Trimethophrim-sulfamethoxazole resistance rate has been found higher than other antibiotics. As penicillin MIC values were at the range of 0.12-2 ​μg/mL frequently, high doses of penicillin treatment might be required in some patients. It is noteworthy that significant decrease in resistance rates in penicillin, erythromycin, clindamycin and tetracycline could be due to the vaccination programme carried out since 2008 in Turkey. As the empiric use of quinolones is high it would be more appropriate to use it according to the susceptibility testing. It is important to determine the regional antimicrobial susceptibility for Streptococcus pneumoniae to select appropriate empirical antimicrobials in the clinical practice.

Ag nanoparticle-decorated chitosan/SrSnO3 nanocomposite for ultrafast elimination of antibiotic linezolid and methylene blue

Effective design of ultrafast new-generation photocatalysts is a challenging task that requires highly dedicated efforts. This research focused on the development and design of ultrafast smart ternary photocatalysts containing SrSnO₃ nanostructures in conjugation with chitosan (CTSN) and silver (Ag) nanoparticles by a very simple and straightforward methodology. Modern analytical tools such as FESEM, TEM, XRD, XPS, FTIR, and UV-Vis spectroscopy were employed to characterize the synthesized nanostructures. XRD and XPS analysis confirmed the successful creation of ternary organization among the Ag, CTSN, and SrSnO₃. The TEM images clearly confirmed that CTSN possessed overlapping micron-sized sheets with a layered morphology, whereas the undoped SrSnO₃ particles exhibited spherical and elongated shapes and particle sizes ranging from 20 to 80 nm. These particles were produced in high density with homogeneously distributed Ag nanoparticles (4-15 nm). The bandgap energy (E_g) for bare SrSnO₃, CTSN/SrSnO₃, and Ag@CTSN/SrSnO₃ nanocomposites was found to be 4.0, 3.94, and 3.7 eV, respectively. The photocatalytic efficiencies of all newly created photocatalysts were evaluated by considering an antibiotic linezolid drug and methylene blue (MB) dye molecule as target analytes. Among all investigated samples, the Ag@CTSN/SrSnO₃ photocatalyst was found to be highly superior, with ultrafast removal of the linezolid drug at 96.02% within 25 min and almost total removal of the MB dye in just 12 min under UV light irradiation. The Ag@CTSN/SrSnO₃ photocatalyst exhibited removal rate that was 3.36 times faster than that of bare SrSnO₃. The present report delivers a highly promising, extremely efficient, and very simple, straightforward treatment methodology for the effective destruction of lethal and notorious pollutants, enabling the appropriate management of current environmental concerns.