Whole genome sequencing of resistance and virulence genes in multi-drug resistant Pseudomonas aeruginosa

BACKGROUND

Pseudomonas aeruginosa is an opportunistic bacterium that causes serious hospital-acquired infections. To assess the risk of clinically isolated P. aeruginosa to human health, we analyzed the resistance and virulence mechanisms of a collection of clinical isolates.

METHODS

This was a retrospective study in which P. aeruginosa isolates collected from January 1, 2018 to August 31, 2019 were analyzed using phenotypic and whole-genome sequencing (WGS) methods. The analysis included 48 clinical samples. Median patient age was 54.0 (29.5) years, and 58.3% of patients were women. Data from the microbiology laboratory database were reviewed to identify P. aeruginosa isolates. All unique isolates available for further testing were included, and related clinical data were collected. Infections were defined as hospital acquired if the index culture was obtained at least 48 h after hospitalization.

RESULTS

High-risk P. aeruginosa clones, including sequence types (STs) ST235 and ST111, were identified, in addition to 12 new STs. The isolates showed varying degrees of biofilm formation ability when evaluated at room temperature, along with reduced metabolic activity, as measured by metabolic staining, suggesting their ability to evade antimicrobial therapy. Most isolates (77.1%) were multidrug resistant (MDR), with the highest resistance and susceptibility rates to beta-lactams and colistimethate sodium, respectively.

CONCLUSIONS

The MDR phenotypes of the examined isolates can be explained by the high prevalence of efflux-mediated resistance- and hydrolytic enzyme-encoding genes. These isolates had high cytotoxic potential, as indicated by the detection of toxin production-related genes.

Impact of bronchoalveolar lavage on the management of immunocompromised hosts

BACKGROUND

Respiratory infections are an important cause of morbidity and mortality in immunocompromised individuals. Fiberoptic bronchoscopy with bronchoalveolar lavage (BAL) is an important tool to detect infectious agents in immunocompromised patients with low respiratory tract infections (LRTI).

RESEARCH QUESTION

BAL changes the management of immunocompromised patients with suspected LRTI.

STUDY DESIGN AND METHODS

Immunocompromised patients with a suspicion of LRTI underwent diagnostic BAL. The primary composite outcome consisted of pre-defined modifications in the management of the immunocompromised patients following BAL. We quantified the impact of bronchoscopy up to 30 days after the procedure.

RESULTS

A total of 2666 visits from 1301 patients were included in the study and immunosuppression was classified as haematological (n = 1040; 544 patients), solid organ transplantation (n = 666; 107 patients) and other causes (n = 960; 650 patients). BAL led to a change in management in 52.36% (n = 1396) of all cases. This percentage, as well as the 30-day mortality differed significantly amongst the three groups. Age, C-reactive protein and aetiology of infection determined significantly the risk of 30-day mortality in all patients. In 1.89% (n = 50) of all cases, a combination of 2 respiratory viral agents was identified and 24.23% (n = 646) were diagnosed with a single respiratory viral agent.

INTERPRETATION

BAL leads to changes in management in the majority of immunosuppressed patients. There is a high prevalence of multimicrobial infections and respiratory viral infections in immunocompromised patients with respiratory symptoms. Individual virus infection is associated with diverse risk of a negative outcome.

18 F-FDG PET/CT in Renal Allograft Tuberculosis Mimicking as Posttransplant Malignancy

ABSTRACT

The most common complications after the renal transplant are infections and malignancies, including posttransplant lymphoproliferative disorders. Tubercular infection in renal allograft recipients is a relatively rare entity. However, nonspecific constitutional symptoms often delay diagnosis, leading to significant morbidity and mortality. We present the 18 F-FDG PET/CT findings in a patient with renal allograft tuberculosis who had clinical and imaging suspicion of posttransplant lymphoproliferative disorder or renal cell carcinoma. Histopathology from the renal lesion revealed tuberculosis.

Discrimination of leptomeningeal carcinomatosis and meningeal inflammation/infection with internal acoustic canal enhancement

PURPOSE

The purpose of this study is to investigate whether the presence and pattern of enhancement at the internal acoustic canal (IAC) could help in discriminating between leptomeningeal carcinomatosis (LCa) and meningeal inflammation/infection (MMI).

METHODS

Magnetic resonance (MR) images of patients with leptomeningeal enhancement were retrospectively evaluated. MR images of the LCa group (n = 33), MMI group (n = 19) and control group (n = 33) were evaluated for the presence, type (moderate/prominent), and localization (unilateral/bilateral) of the IAC enhancement.

RESULTS

The presence of IAC enhancement was significantly more common in patients with LCa (p < 0.001). In 73.7 % of patients with MMI, no contrast enhancement was observed in the IAC. In patients with contrast enhancement in the IAC, the risk of LCa in the etiology is 20 times greater than the risk of having MMI. Seventy-five percent of the IAC enhancement seen in LCa patients and 20 % of the IAC enhancements seen in MMI patients was bilateral. This difference was statistically significant (p = 0.029).

CONCLUSION

Intense contrast enhancement of the IAC can be a marker for LCa.

Etiology and antimicrobial resistance patterns in chronic osteomyelitis of the tibia: an 11-year clinical experience

PURPOSE

To analyze changes in tendency of etiology and of antimicrobial resistance patterns to most common local and systemic antibiotics in chronic osteomyelitis of the tibia (COM-T) in a Level I trauma center over an 11-year period.

METHODS

A retrospective review including all patients with COM-T who were surgically treated from January 2009 to December 2019. Patients were divided into two period groups: 2009-2014 and 2015-2019. Microbiologic etiology was analyzed. Bacterial resistance patterns evaluation was based on the Magiorakos et al. classification, including proportions of multidrug-resistant organisms (MDROs, acquired non-susceptibility to at least one agent in three or more antimicrobial categories), extensively drug-resistant (XDR) and pan drug-resistant (PDR) organisms encountered.

RESULTS

A total of 173 episodes of COM-T were identified. Monomicrobial infections represented 47.4% of all cases, while 28.3% had polymicrobial infections. Negative deep-bone cultures were identified in 24.3% of the patients. The most commonly isolated microorganisms were coagulase-negative Staphylococci (24.5%) and S. aureus (20.5%). No differences were found when comparing Gram-positive infections between periods (58.3% for 2009-2014 vs. 46.7% for 2015-2019; p = 0.10). Findings were similar for Gram-negative infections (37% vs. 33.7%; p = 0.62), although more polymicrobial infections were detected (24.7% vs. 33.3%, respectively; p = 0.359). MDROs were involved in 15% of the cases, with an upward trend when comparing both periods (12.8% vs. 23.6%; p = 0.07). The most-used combination of local antibiotics-glycopeptide (vancomycin) plus aminoglycoside (gentamicin or tobramycin)-was met with low rates of resistance in the most frequently isolated microorganisms.

CONCLUSION

According to the results of the present study, rates of Gram-positive and Gram-negative infections remained consistent during the two study periods, but with an upward trend in MDRO and polymicrobial infections detected. The local combination of a glycopeptide plus an aminoglycoside was effective in treating the most frequently isolated microorganisms.

Periprosthetic Infection in Patients With Multiple Joint Arthroplasties

The number of total joint arthroplasties performed in the United States is increasing every year. Owing to the aging population and excellent long-term prosthesis survival, 45% of patients who undergo joint arthroplasty will receive two or more joint arthroplasties during their lifetimes. Periprosthetic joint infection (PJI) is among the most common complications after arthroplasty. Evaluation and treatment of PJI in patients with multiple joint arthroplasties is challenging, and no consensus exists for the optimal management. Multiple PJI can occur simultaneously, synchronous, or separated by extended time, metachronous. Patient risk factors for both scenarios have been reported and may guide evaluation and long-term management. Whether to perform joint aspiration for asymptomatic prosthesis in the presence of suspected PJI in patients with multiple joint arthroplasties is controversial. Furthermore, no consensus exists regarding whether patients who have multiple joint arthroplasties and develop PJI in a single joint should be considered for prolonged antibiotic prophylaxis to reduce the risk of future infections. Finally, the optimal treatment of synchronous joint infections whether by débridement, antibiotics and implant retention, and one-stage or two-stage revision has not been defined. This review will summarize the best information available and provide pragmatic management strategies.

Embolic stroke and misidentification candida species endocarditis: Case presentation and literature review

Fungal endocarditis is a rare but serious form of infective endocarditis associated with high morbidity and mortality. Among fungal pathogens, Candida species are the most frequently isolated and commonly found in individuals with predisposing factors, such as prosthetic heart valves. The clinical presentation of endocarditis is highly variable and nonspecific, often including symptoms and signs of embolization. In this paper, we present a case of fungal prosthetic valve endocarditis in which the initial presentation was an acute ischemic stroke. The initial misidentification of Candida famata was attributed to limitations in the presumptive methodology used through selective chromogenic culture identification. However, the surgical specimen underwent mass spectrometry, leading to the correct identification of Candida guilliermondii instead of Candida famata. Furthermore, we conducted a non-systematic narrative review of the literature on Candida endocarditis. Our findings underscore the importance of considering fungal endocarditis in the differential diagnosis of patients with possible extracardiac complications, particularly those with a history of heart valve replacement. Early diagnosis and a comprehensive treatment strategy tailored by species identification and antifungal susceptibility testing are crucial in improving patient outcomes.

Predominance of multidrug-resistant bacteria causing urinary tract infections among symptomatic patients in East Africa: a call for action

Background

In low- and middle-income countries, antibiotics are often prescribed for patients with symptoms of urinary tract infections (UTIs) without microbiological confirmation. Inappropriate antibiotic use can contribute to antimicrobial resistance (AMR) and the selection of MDR bacteria. Data on antibiotic susceptibility of cultured bacteria are important in drafting empirical treatment guidelines and monitoring resistance trends, which can prevent the spread of AMR. In East Africa, antibiotic susceptibility data are sparse. To fill the gap, this study reports common microorganisms and their susceptibility patterns isolated from patients with UTI-like symptoms in Kenya, Tanzania and Uganda. Within each country, patients were recruited from three sites that were sociodemographically distinct and representative of different populations.

Methods

UTI was defined by the presence of >104 cfu/mL of one or two uropathogens in mid-stream urine samples. Identification of microorganisms was done using biochemical methods. Antimicrobial susceptibility testing was performed by the Kirby-Bauer disc diffusion assay. MDR bacteria were defined as isolates resistant to at least one agent in three or more classes of antimicrobial agents.

Results

Microbiologically confirmed UTI was observed in 2653 (35.0%) of the 7583 patients studied. The predominant bacteria were Escherichia coli (37.0%), Staphylococcus spp. (26.3%), Klebsiella spp. (5.8%) and Enterococcus spp. (5.5%). E. coli contributed 982 of the isolates, with an MDR proportion of 52.2%. Staphylococcus spp. contributed 697 of the isolates, with an MDR rate of 60.3%. The overall proportion of MDR bacteria (n = 1153) was 50.9%.

Conclusions

MDR bacteria are common causes of UTI in patients attending healthcare centres in East African countries, which emphasizes the need for investment in laboratory culture capacity and diagnostic algorithms to improve accuracy of diagnosis that will lead to appropriate antibiotic use to prevent and control AMR.

Debridement, antibiotics, and implant retention (DAIR) for the early prosthetic joint infection of total knee and hip arthroplasties: a systematic review

PURPOSE

Early periprosthetic joint infection (PJI) represents one of the most fearsome complications of joint replacement. No international consensus has been reached regarding the best approach for early prosthetic knee and hip infections. The aim of this updated systematic review is to assess whether debridement, antibiotics, and implant retention (DAIR) is an effective choice of treatment in early postoperative and acute hematogenous PJI.

METHODS

This systematic review was performed using the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. The diagnostic criteria defining a PJI, the most present pathogen, and the days between the index procedure and the onset of the PJI were extracted from the selected articles. Additionally, the mean follow-up, antibiotic regimen, and success rate of the treatment were also reported.

RESULTS

The articles included provided a cohort of 970 patients. Ten studies specified the joint of their cohort in PJIs regarding either hip prostheses or knee prostheses, resulting in 454 total knees and 460 total hips. The age of the patients ranged from 18 to 92 years old. Success rates for the DAIR treatments in the following cohort ranged from 55.5% up to a maximum of 90% (mean value of 71%).

CONCLUSION

Even though the DAIR procedure is quite limited, it is still considered an effective option for patients developing an early post-operative or acute hematogenous PJI. However, there is a lack of studies, in particular randomized control trials (RCTs), comparing DAIR with one-stage and two-stage revision protocols in the setting of early PJIs, reflecting the necessity to conduct further high-quality studies to face the burden of early PJI.

Deciphering mechanisms affecting cefepime-taniborbactam in vitro activity in carbapenemase-producing Enterobacterales and carbapenem-resistant Pseudomonas spp. isolates recovered during a surveillance study in Spain

PURPOSE

To characterize the resistance mechanisms affecting the cefepime-taniborbactam combination in a collection of carbapenemase-producing Enterobacterales (CPE) and carbapenem-resistant Pseudomonas spp. (predominantly P. aeruginosa; CRPA) clinical isolates.

METHODS

CPE (n = 247) and CRPA (n = 170) isolates were prospectively collected from patients admitted to 8 Spanish hospitals. Susceptibility to cefepime-taniborbactam and comparators was determined by broth microdilution. Cefepime-taniborbactam was the most active agent, inhibiting 97.6% of CPE and 67.1% of CRPA (MICs ≤ 8/4 mg/L). All isolates with cefepime-taniborbactam MIC > 8/4 mg/L (5 CPE and 52 CRPA) and a subset with MIC ≤ 8/4 mg/L (23 CPE and 24 CRPA) were characterized by whole genome sequencing.

RESULTS

A reduced cefepime-taniborbactam activity was found in two KPC-ST307-Klebsiella pneumoniae isolates with altered porins [KPC-62-K. pneumoniae (OmpA, OmpR/EnvZ), KPC-150-K. pneumoniae (OmpK35, OmpK36)] and one each ST133-VIM-1-Enterobacter hormaechei with altered OmpD, OmpR, and OmpC; IMP-8-ST24-Enterobacter asburiae; and NDM-5-Escherichia coli with an YRIN-inserted PBP3 and a mutated PBP2. Among the P. aeruginosa (68/76), elevated cefepime-taniborbactam MICs were mostly associated with GES-5-ST235, OXA-2+VIM-2-ST235, and OXA-2+VIM-20-ST175 isolates also carrying mutations in PBP3, efflux pump (mexR, mexZ) and AmpC (mpl) regulators, and non-carbapenemase-ST175 isolates with AmpD-T139M and PBP3-R504C mutations. Overall, accumulation of these mutations was frequently detected among non-carbapenemase producers.

CONCLUSIONS

The reduced cefepime-taniborbactam activity among the minority of isolates with elevated cefepime-taniborbactam MICs is not only due to IMP carbapenemases but also to the accumulation of multiple resistance mechanisms, including PBP and porin mutations in CPE and chromosomal mutations leading to efflux pumps up-regulation, AmpC overexpression, and PBP modifications in P. aeruginosa.

Successful Implant Retention in a Chronified Hematogenous Bilateral Periprosthetic Hip Joint Infection With Enterococcus faecalis

We present a case with bilateral hematogenous hip periprosthetic joint infection with Enterococci which could be treated successfully with implant retention despite chronification and partial loosening. A debridement and replacement of the modular components was carried out with replacement of a loose acetabular cup on the right side. Considering poor local infection control, antibiotic treatment was enhanced by local application of vancomycin. In the present case, treatment of chronic enterococcal periprosthetic joint infection while preserving the implants was successful despite unfavorable odds. Considering the duration of infection, causative microorganism, and loosening of one of the implants, staged exchange of both hip replacements would have been the standard procedure. This case illustrates that some concepts have to be challenged from time to time.

Outcomes After Successful Debridement, Antibiotic, and Implant Retention Therapy for Periprosthetic Joint Infection in Total Knee Arthroplasty

BACKGROUND

Controversy surrounds debridement, antibiotic and implant retention (DAIR) for treatment of acute periprosthetic joint infection (PJI). Data regarding DAIR's rate of infection resolution is variable with little investigation of functional outcomes.

METHODS

We identified 191 DAIR cases at a single institution from 2008 to 2020. Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS-JR) and Patient Reported Outcome Measurement Information System-10 (PROMIS) scores were collected. Patient Reported Outcome Scores were obtained from 60 cases. Median follow-up (IQR) was 4.5 (2.1 to 7.6) versus 3.0 (1.2 to 5.3) years for the control group. Mean scores were compared to a cohort of uncomplicated total knee arthroplasties matched by age, body mass index, and sex using generalized linear models adjusted for follow-up duration. Kaplan-Meier survivorship curves for PJI were constructed.

RESULTS

Mean Patient Reported Outcome Scores for the DAIR cohort were 57.2 ± 19.7 for KOOS-JR, 41.6 ± 7.1 for PROMIS physical health (PH), and 46.6 ± 8.7 for PROMIS mental health (MH). Mean control group values were 65.8 ± 21.0 for KOOS-JR, 44.6 ± 8.4 for PROMIS PH, and 49.2 ± 9.2 for PROMIS MH. No difference was observed in KOOS-JR (P = .83) or PROMIS MH (P = .11). PROMIS PH was lower in the DAIR cohort compared to the control group (P = .048). Median follow-up (years) for all 191 cases was 5.9 (range, 0.5 to 13.1). Survivorship (years) without subsequent operation for infection was 84% at 1, 82% at 2, and 79% at 5.

CONCLUSION

Knee and MH outcomes in successful DAIR procedures were similar to uncomplicated total knee arthroplasty. DAIR's success rate was 79% in treating acute PJI at 5 years.

LEVEL OF EVIDENCE

Level III.

What Is the Most Effective Treatment for Periprosthetic Joint Infection After Total Joint Arthroplasty in Patients with Rheumatoid Arthritis?: A Systematic Review

BACKGROUND

Rheumatoid arthritis (RA) is a risk factor for periprosthetic joint infection (PJI) after total joint arthroplasty (TJA). The purpose of this study was to perform a systematic review comparing the failure rates of debridement, antibiotics, and implant retention (DAIR), one-stage exchange arthroplasty/revision (OSR), and 2-stage exchange arthroplasty/revision (TSR) for RA patients with PJI and identify risk factors in the RA population associated with increased treatment failure rate.

METHODS

PubMed, Ovid MEDLINE, and Ovid Embase databases were screened with the terms "rheumatoid arthritis," "total joint arthroplasty," "prosthetic joint infection," and "treatment for PJI" on August 29, 2021. Four hundred ninety-one studies were screened, of which 86 were evaluated. The primary outcome evaluated was failure of surgical treatment for PJI.

RESULTS

Ten retrospective cohort studies were included after full-text screening, yielding 401 patients with RA. Additional demographic and PJI management data were obtained for 149 patients. Patients with RA who underwent TSR demonstrated a lower failure rate (26.8%) than both DAIR (60.1%) and OSR (39.2%) (χ2 = 37.463, p < 0.00001). Patients with RA who underwent DAIR had a 2.27 (95% CI, 1.66-3.10) times higher risk of experiencing treatment failure than those who underwent TSR. Among risk factors, there was a significant difference in the C-reactive protein of patients who did vs. did not experience treatment failure (p = 0.02).

CONCLUSION

TSR has a higher rate of success in the management of PJI patients with RA compared with DAIR and OSR. The complete removal of the infected prosthesis and delayed reimplantation may lower the treatment failure rate.

LEVEL OF EVIDENCE

Level III. See Instructions for Authors for a complete description of levels of evidence.

Staphylococcus epidermidis joint isolates: Whole-genome sequencing demonstrates evidence of hospital transmission and common antimicrobial resistance

OBJECTIVE

We investigated genetic, epidemiologic, and environmental factors contributing to positive Staphylococcus epidermidis joint cultures.

DESIGN

Retrospective cohort study with whole-genome sequencing (WGS).

PATIENTS

We identified S. epidermidis isolates from hip or knee cultures in patients with 1 or more prior corresponding intra-articular procedure at our hospital.

METHODS

WGS and single-nucleotide polymorphism-based clonality analyses were performed, including species identification, in silico multilocus sequence typing (MLST), phylogenomic analysis, and genotypic assessment of the prevalence of specific antibiotic resistance and virulence genes. Epidemiologic review was performed to compare cluster and noncluster cases.

RESULTS

In total, 60 phenotypically distinct S. epidermidis isolates were identified. After removal of duplicates and impure samples, 48 isolates were used for the phylogenomic analysis, and 45 (93.7%) isolates were included in the clonality analysis. Notably, 5 S. epidermidis strains (10.4%) showed phenotypic susceptibility to oxacillin yet harbored mecA, and 3 (6.2%) strains showed phenotypic resistance despite not having mecA. Smr was found in all isolates, and mupA positivity was not observed. We also identified 6 clonal clusters from the clonality analysis, which accounted for 14 (31.1%) of the 45 S. epidermidis isolates. Our epidemiologic investigation revealed ties to common aspirations or operative procedures, although no specific common source was identified.

CONCLUSIONS

Most S. epidermidis isolates from clinical joint samples are diverse in origin, but we identified an important subset of 31.1% that belonged to subclinical healthcare-associated clusters. Clusters appeared to resolve spontaneously over time, suggesting the benefit of routine hospital infection control and disinfection practices.

In vitro activity of cefiderocol against a global collection of carbapenem-resistant Pseudomonas aeruginosa with a high level of carbapenemase diversity

OBJECTIVES

To determine the in vitro activity of cefiderocol in a global collection of carbapenem-resistant Pseudomonas aeruginosa including >200 carbapenemase-producing isolates.

METHODS

Isolates (n = 806) from the ERACE-PA Surveillance Program were assessed. Broth microdilution MICs were determined for cefiderocol (iron-depleted CAMHB) and comparators (CAMHB). Susceptibility was interpreted by CLSI and EUCAST breakpoints and reported as percent of isolates. The MIC distribution of cefiderocol in the entire cohort and by carbapenemase status was assessed.

RESULTS

In the entire cohort, cefiderocol was the most active agent (CLSI 98% susceptible; EUCAST 95% susceptible; MIC50/90, 0.25/2 mg/L). Amikacin (urinary only breakpoint) was the second most active, with 70% of isolates testing as susceptible. The percentage of isolates susceptible to all other agents was low (<50%) including meropenem/vaborbactam, imipenem/relebactam, piperacillin/tazobactam and levofloxacin. Cefiderocol maintained significant activity against the most commonly encountered carbapenemases including VIM- (CLSI 97% susceptible; EUCAST 92% susceptible) and GES (CLSI 100% susceptible; EUCAST 97% susceptible)-harbouring isolates. The cefiderocol MIC distribution was similar regardless of carbapenemase status, with MIC50/90 values of 0.5/4 mg/L, 0.5/2 mg/L and 0.25/1 mg/L for MBL, serine carbapenemase and molecular carbapenemase-negative isolates, respectively.

CONCLUSIONS

Cefiderocol displayed potent in vitro activity in this global cohort of carbapenem-resistant P. aeruginosa including >200 carbapenemase-harbouring isolates. Cefiderocol was highly active against MBL-producing isolates, where treatment options are limited. These data can help guide empirical therapy guidelines based on local prevalence of carbapenemase-producing P. aeruginosa or in response to rapid molecular diagnostics.

Laboratory and clinical management capacity for invasive fungal infections: the Italian landscape

BACKGROUND

We assessed the laboratory diagnosis and treatment of invasive fungal disease (IFD) in Italy to detect limitations and potential for improvement.

METHODS

The survey was available online at www.clinicalsurveys.net/uc/IFI management capacity/, and collected variables such as (a) institution profile, (b) perceptions of IFD in the respective institution, (c) microscopy, (d) culture and fungal identification, (e) serology, (f) antigen detection, (g) molecular tests, (h) susceptibility testing and (i) therapeutic drug monitoring (TDM).

RESULTS

The laboratory capacity study received responses from 49 Italian centres, with an equitable geographical distribution of locations. The majority of respondents (n = 36, 73%) assessed the occurrence of IFD as moderate-high, with Aspergillus spp. being the pathogen of highest concern, followed by Candida spp. and Mucorales. Although 46 (94%) of the institutions had access to microscopy, less than half of them performed direct microscopy on clinical specimens always when IFD was suspected. Cultures were available in all assessed laboratories, while molecular testing and serology were available in 41 (83%), each. Antigen detection tests and antifungal drugs were also generally accessible (> 90%) among the participating institutions. Nevertheless, access to TDM was limited (n = 31, 63%), with a significant association established between therapeutic drug monitoring availability and higher gross domestic product per capita.

CONCLUSIONS

Apart from TDM, Italy is adequately prepared for the diagnosis and treatment of IFD, with no significant disparities depending on gross domestic product. Future efforts may need to focus on enhancing the availability and application of direct microscopic methods, as well as TDM, to promote optimal treatment and better patient outcomes.

Two-dimensional liquid chromatography measurement of meropenem concentration in synovial fluid of patients with periprosthetic joint infection

Periprosthetic joint infection (PJI) is a catastrophic complication following joint replacement surgery. One potential treatment approach for PJI could be the combination of one-stage revision and intra-articular infusion of antibiotics. Meropenem is one of the commonly used intra-articular antibiotics in our institution. Determining the concentration of meropenem in the joint cavity could be crucial for optimizing its local application, effectively eradicating biofilm infection, and improving PJI treatment outcomes. In this study, we developed a simple, precise, and accurate method of two-dimensional liquid chromatography (2D-LC) for determining the concentration of meropenem in human synovial fluid. The method was then validated based on the guidelines of the Food and Drug Administration and the Chinese Pharmacopoeia. Meropenem showed good linearity in the range of 0.31-25.01 μg/mL (r ≥ .999). Selectivity, intra-day and inter-day precision and accuracy, extraction recovery, and stability validation results were all within the acceptance range. This method has been successfully applied to the determination of synovial fluid samples from PJI patients, providing a useful detection method for meropenem therapeutic drug monitoring (TDM) in PJI patients.

Protective effects of naringin on colistin-induced damage in rat testicular tissue: Modulating the levels of Nrf-2/HO-1, AKT-2/FOXO1A, Bax/Bcl2/Caspase-3, and Beclin-1/LC3A/LC3B signaling pathways

Antimicrobial agent resistance has become a growing health issue across the world. Colistin (COL) is one of the drugs used in the treatment of multidrug-resistant bacteria resulting in toxic effects. Naringin (NRG), a natural flavonoid, has come to the fore as its antioxidant, anti-inflammatory, and antiapoptotic activities. The aim of the present study was to determine whether NRG has protective effects on COL-induced toxicity in testicular tissue. Thirty-five male Spraque rats were randomly divided into five groups (n = 7 per group): Control, COL, NRG, COL + NRG 50, COL + NRG 100. COL (15 mg/kg b.w., i.p., once per/day), and NRG (50 or 100 mg/kg, oral, b.w./once per/day) were administered for 7 days. The parameters of oxidative stress, inflammation, apoptosis, and autophagic damage were evaluated by using biochemical, molecular, western blot, and histological methods in testicular issues. NRG treatment reversed the increased malondialdehyde level and reduced antioxidants (superoxide dismutase, catalase, glutathione peroxidase, and glutathione) levels due to COL administration (p < 0.001), and oxidative stress damage was mitigated. Nuclear factor erythroid 2-related factor-2 pathway, one of the antioxidant defence systems, was stimulated by NRG (p < 0.001). NRG treatment reduced the levels of markers for the pathways of apoptotic (p < 0.001) and autophagic (p < 0.001) damages induced by COL. Sperm viability and the live/dead ratio were reduced by COL but enhanced by NRG treatment. Testicular tissue integrity was damaged by COL but showed a tendency to improve by NRG. In conclusion, COL exhibited toxic effect on testicular tissue by elevating the levels of oxidative stress, apoptosis, autophagy, inflammation, and tissue damage. NRG demonstrated a protective effect by alleviating toxic damage.

A case of hypervirulent K1-ST23 Klebsiella pneumoniae endocarditis and papillary muscle rupture secondary to multiple site abscesses

Hypervirulent Klebsiella pneumoniae (hvKP) causes multisite infections and abscesses. However, endocarditis is a rare presentation of hvKP infection. Herein, we report a case of K. pneumoniae native valve infective endocarditis secondary to community-acquired liver and prostate abscesses. The patient developed papillary muscle rupture, leading to mitral regurgitation, and underwent emergent mitral valve replacement. The diagnosis of endocarditis was confirmed microbiologically and histologically. The causative strain belonged to the hypermucoid K1 capsular genotype and possessed the rmpA gene. The genome sequence was deposited in GenBank under the accession number JAQZBZ000000000.

Molecular Study of Pneumocystis jirovecii in Respiratory Samples of HIV Patients in Chile

Pneumocystis is an opportunistic fungus that causes potentially fatal pneumonia (PCP) in immunocompromised patients. The objective of this study was to determine the prevalence of P. jirovecii in HIV patients through phenotypic and molecular study, to investigate the genetic polymorphisms of P. jirovecii at the mitochondrial gene mtLSU and at the nuclear dihydropteroate synthase gene (DHPS), and by analysis of molecular docking to study the effect of DHPS mutations on the enzymatic affinity for sulfamethoxazole. A PCP prevalence of 28.3% was detected, with mtLSU rRNA genotypes 3 (33.3%) and 2 (26.6%) being the most common. A prevalence of 6.7% (1/15) mutations in the DHPS gene was detected, specifically at codon 55 of the amino acid sequence of dihydropteroate synthase. Molecular docking analysis showed that the combination of mutations at 55 and 98 codons is required to significantly reduce the affinity of the enzyme for sulfamethoxazole. We observed a low rate of mutations in the DHPS gene, and molecular docking analysis showed that at least two mutations in the DHPS gene are required to significantly reduce the affinity of dihydropteroate synthase for sulfamethoxazole.

Prevalence of S. aureus and/or MRSA in hospitalized patients with diabetic foot and establishment of LAMP methods for rapid detection of the SCCmec gene

BACKGROUND

Patients with diabetic feet are prone to be infected due to the impaired immune system. However, the prognostic outcome of different microbial infections remains controversial. Identification and rapid screening of the pathogenic microorganisms that pose the greatest threat to the prognosis of patients with diabetic foot infections (DFIs) is critical.

METHODS

Clinical data were statistically analyzed, which were obtained from 522 patients with DFIs, including pathogenic bacterial culture results and treatment outcomes at the last return visit. In addition, a loop-mediated isothermal amplification (LAMP) detection method was developed to identify the prevalent subtype of methicillin-resistant Staphylococcus aureus (MRSA) in DFIs patients. This study was approved by the Ethics Committee of Nanfang Hospital (NFEC-202012-K6) and registered on ClinicalTrials.gov (NCT04916457) on June 1, 2021.

RESULTS

We found that the proportion of patients with infections of Staphylococcus aureus (S. aureus) and MRSA was 27.7% (145/522) and 33.7% (49/145), respectively. Additionally, the incidence of osteomyelitis was 46.9% (23/49) and amputation/disability was 40.8% (20/49) in patients with MRSA infection, which were significantly higher compared to patients with other types of bacterial infections such as methicillin-susceptible Staphylococcus aureus (MSSA). Notably, we demonstrated that the main prevalent subtype of MRSA in DFIs patients in our hospital was Staphylococcal chromosomal cassettes mec (SCCmec) type II. In addition, it only takes 1.5 h to complete the entire experimental procedure in this LAMP assay, providing high sensitivity (100%) and specificity (77.8%) in hospitalized patients with DFIs.

CONCLUSIONS

We demonstrated there is a very high rate of MRSA isolation in patients with DFIs and revealed that patients infected with MRSA are at a higher risk of developing osteomyelitis, and amputation or disability. Importantly, we have developed a method for quickly screening newly admitted patients for MRSA.

How are Oral Antibiotics Being Used in Total Joint Arthroplasty? A Review of the Literature

While the role and benefit of perioperative intravenous (IV) antibiotics in patients undergoing total joint arthroplasty (TJA) is well-established, oral antibiotic use in TJA remains a controversial topic with wide variations in practice patterns. With this review, we aimed to better educate the orthopedic surgeon on when and how oral antibiotics may be used most effectively in TJA patients, and to identify gaps in the literature that could be clarified with targeted research. Extended oral antibiotic prophylaxis (EOAP) use in high-risk primary, aseptic revision, and exchange TJA for infection may be useful in decreasing periprosthetic joint infection (PJI) rates. When prescribing oral antibiotics either as EOAP or for draining wounds, patient factors, type of surgery, and type of infectious organisms should be considered in order to optimally prevent and treat PJI. It is important to maintain antibiotic stewardship by administering the proper duration, dose, and type of antibiotics and by consulting infectious disease when necessary.

State-of-the-Art Review: Persistent Enterococcal Bacteremia

Persistent enterococcal bacteremia is a commonly encountered and morbid syndrome without a strong evidence base for optimal management practices. Here we highlight reports on the epidemiology of enterococcal bacteremia to better describe and define persistent enterococcal bacteremia, discuss factors specific to Enterococcus species that may contribute to persistent infections, and describe a measured approach to diagnostic and therapeutic strategies for patients with these frequently complicated infections. The diagnosis of persistent enterococcal bacteremia is typically clinically evident in the setting of repeatedly positive blood culture results; instead, the challenge is to determine in an accurate, cost-effective, and minimally invasive manner whether any underlying nidus of infection (eg, endocarditis or undrained abscess) is present and contributing to the persistent bacteremia. Clinical outcomes for patients with persistent enterococcal bacteremia remain suboptimal. Beyond addressing host immune status if relevant and pursuing source control for all patients, management decisions primarily involve the selection of the proper antimicrobial agent(s). Options for antimicrobial therapy are often limited in the setting of intrinsic and acquired antimicrobial resistance among enterococcal clinical isolates. The synergistic benefit of combination antimicrobial therapy has been demonstrated for enterococcal endocarditis, but it is not clear at present whether a similar approach will provide any clinical benefit to some or all patients with persistent enterococcal bacteremia.

How We Approach Suppressive Antibiotic Therapy Following Debridement, Antibiotics, and Implant Retention for Prosthetic Joint Infection

The optimal treatment of prosthetic joint infection (PJI) remains uncertain. Patients undergoing debridement, antibiotics, and implant retention (DAIR) receive extended antimicrobial treatment, and some experts leave patients at perceived highest risk of relapse on suppressive antibiotic therapy (SAT). In this narrative review, we synthesize the literature concerning the role of SAT to prevent treatment failure following DAIR, attempting to answer 3 key questions: (1) What factors identify patients at highest risk for treatment failure after DAIR (ie, patients with the greatest potential to benefit from SAT), (2) Does SAT reduce the rate of treatment failure after DAIR, and (3) What are the rates of treatment failure and adverse events necessitating treatment discontinuation in patients receiving SAT? We conclude by proposing risk-benefit stratification criteria to guide use of SAT after DAIR for PJI, informed by the limited available literature.

Clinical Characteristics, Treatment, and Outcomes of Veterans with Cerebrospinal Fluid Culture Positive for Gram-Negative Rod Bacteria: A Retrospective Analysis over 18 Years in 125 Veterans Health Administration Hospitals

Optimal management for patients with bacterial ventriculitis/meningitis due to Gram-negative rods (GNRs) has yet to be well investigated. We assessed the clinical characteristics, treatment, and outcomes of patients with a positive cerebrospinal fluid (CSF) culture for GNRs. We conducted a retrospective cohort study of all patients with a positive CSF culture within the Veterans Health Administration (VHA) system during 2003-2020. Clinical and microbiological characteristics between the true meningitis and contamination groups were compared. Of the 5919 patients with positive CSF cultures among 125 nationwide VHA acute-care hospitals, 297 (5.0%) were positive for GNRs. Among 262 patients analyzed, 156 (59.5%) were assessed as patients with true meningitis, and 106 (40.5%) were assessed as patients with contaminated CSF cultures. Patients with true meningitis had a significantly higher CSF protein (median 168 vs 57 mg/dL, p < 0.001), CSF white blood cell count (median 525 vs 3/µL, p = 0.008) and percentage of neutrophils in CSF (median 88 vs 4%, p < 0.001). Enterobacterales were more common in the true meningitis group, while unidentified GNR or polymicrobial CSF cultures were more common in the contamination group. The all-cause 90-day mortality was 25.0% (39/156) in patients with true meningitis and 10.4% (11/106) in those with contaminated CSF cultures. None of the 11 patients with contaminated CSF cultures who died were considered due to missed meningitis. More than 40% of patients with a positive CSF culture with GNR did not receive treatment without negative consequences. Careful clinical judgment is required to decide whether to treat such patients.

Oligoribonuclease mediates high adaptability of P. aeruginosa through metabolic conversion

BACKGROUND

Oligoribonuclease (orn) of P. aeruginosa is a highly conserved exonuclease, which can regulate the global gene expression levels of bacteria through regulation of both the nanoRNA and c-di-GMP. NanoRNA can regulate the expression of the bacterial global genome as a transcription initiator, and c-di-GMP is the most widely second messenger in bacterial cells.

OBJECTIVE

This study seeks to elucidate on the regulation by orn on pathogenicity of P. aeruginosa.

METHODS

P. aeruginosa with orn deletion was constructed by suicide plasmid homologous recombination method. The possible regulatory process of orn was analyzed by TMT quantitative labeling proteomics. Then experiments were conducted to verify the changes of Δorn on bacterial motility, virulence and biofilm formation. Bacterial pathogenicity was further detected in cell and animal skin trauma models. ELISA detection c-di-GMP concentration and colony aggregation and biofilm formation were observed by scanning electron microscope.

RESULTS

orn deletion changed the global metabolism of P. aeruginosa and reduced intracellular energy metabolism. It leads to the disorder of the quorum sensing system, the reduction of bacterial motility and virulence factors pyocyanin and rhamnolipids. But, orn deletion enhanced pathogenicity in vitro and in vivo, a high level of c-di-GMP and biofilm development of P. aeruginosa.

CONCLUSION

orn regulates the ability of P. aeruginosa to adapt to the external environment.

[Translated article] Descriptive study of spinal instrumentation-related infections in a tertiary hospital

INTRODUCTION

Spinal instrumentation-related infections (SIRI) are one of the main causes of post-surgical complication and comorbidity. Our objective was to describe the clinical and microbiological characteristics, treatment and prognosis of these infections.

MATERIAL AND METHODS

We conducted a retrospective study in our institution (2011-2018) including adult patients undergoing spinal instrumentation who met the diagnostic criteria for confirmed infection. Superficial surgical wound and deep intraoperative samples were processed for microbiological culture. The medical and orthopaedic team was always the same.

RESULTS

Forty-one cases were diagnosed of which 39 patients (95.1%) presented early infection (<3 months after initial surgery) with symptoms in the first two weeks, mean CRP at diagnosis was 133mg/dl and 23% associated bacteremia. The remaining two patients (4.8%) were chronic infections (symptoms >3 months after surgery). The treatment of choice in early infections was the Debridement, Antibiotics and Implant Retention (DAIR) strategy without removal of the bone graft, which successfully resolved 84.2% of the infections. The main aetiology was gram-positive (Staphylococcus aureus: 31.7%), followed by gram-negative and polymicrobial flora. Antibiotics were optimised according to cultures with a mean duration of 12 weeks.

CONCLUSIONS

In early infections, early diagnosis and DAIR strategy (with bone graft retention) demonstrated a healing rate higher than 80%.

Genomic diversity of β-lactamase producing Pseudomonas aeruginosa in Iran; the impact of global high-risk clones

BACKGROUND

Hospital-acquired infections caused by multidrug-resistant Pseudomonas aeruginosa incline hospital stay and costs of treatment that resulted in an increased mortality rate. The frequency of P. aeruginosa high-risk clones producing carbapenemases was investigated in our clinical samples.

METHODS

In this cross-sectional study, 155 non-repetitive P. aeruginosa isolates were included from different medical centers of Iran. Antibiotic susceptibility testing was determined, and the presence of β-lactamases were sought by phenotypic and genotypic methods. The clonal relationship of all isolates was investigated, and multi-locus sequence typing (MLST) was used for finding the sequence types of carbapenemase-producers.

RESULTS

The agent with highest percent susceptibility rate was recorded for colistin (94.9%). MOX and FOX were found both as low as 1.95% (3/155). The most frequent narrow spectrum β-lactamase was SHV with 7.7% (12/155) followed by PER, OXA-1, and TEM with the frequency of 7.1% (11/155), 3.2% (5/155), and 1.3% (2/155), respectively. Carbapenemases were detected in 28 isolates (18%). The most frequent carbapenemase was IMP with 9% (14/155) followed by NDM, 8.4% (13/155). OXA-48 and VIM were also detected both per one isolate (0.65%). MLST of carbapenem resistant P. aeruginosa isolates revealed that ST244, ST664, ST235, and ST357 were spread in subjected clinical settings. REP-PCR uncovered high genomic diversity in our clinical setting.

CONCLUSION

Clonal proliferation of ST235 strain plays a key role in the propagation of MDR pattern in P. aeruginosa. Our data showed that high-risk clones has distributed in Iran, and programs are required to limit spreading of these clones.

The critically ill older patient with sepsis: a narrative review

Sepsis is a significant public health concern, particularly affecting individuals above 70 years in developed countries. This is a crucial fact due to the increasing aging population, their heightened vulnerability to sepsis, and the associated high mortality rates. However, the morbidity and long-term outcomes are even more notable. While many patients respond well to timely and appropriate interventions, it is imperative to enhance efforts in identifying, documenting, preventing, and treating sepsis. Managing sepsis in older patients poses greater challenges and necessitates a comprehensive understanding of predisposing factors and a heightened suspicion for diagnosing infections and assessing the risk of sudden deterioration into sepsis. Despite age often being considered an independent risk factor for mortality and morbidity, recent research emphasizes the pivotal roles of frailty, disease severity, and comorbid conditions in influencing health outcomes. In addition, it is important to inquire about the patient's preferences and establish a personalized treatment plan that considers their potential for recovery with quality of life and functional outcomes. This review provides a summary of the most crucial aspects to consider when dealing with an old critically ill patient with sepsis.

Emergence of cefiderocol resistance during ceftazidime/avibactam treatment caused by a large genomic deletion, including ampD and piuCD genes, in Pseudomonas aeruginosa

We report the emergence of cefiderocol resistance during the treatment of a ST312 Pseudomonas aeruginosa respiratory infection with ceftazidime/avibactam. whole genome sequencing (WGS) revealed that resistance was caused by a large genomic deletion, including PiuDC (iron transport system) and AmpD (ampC negative regulator), driven by the integration of phage DNA. Thus, our findings alert that this type of deletion could be an efficient (two mechanisms in one step) specific cefiderocol resistance mechanism that might occur nonspecifically upon treatment with β-lactams that select for AmpC overexpression.

Update on the epidemiology, diagnosis, and management of infective endocarditis: A review

Despite advancements in the diagnosis and treatment of infective endocarditis (IE), the burden of IE has remained relatively high over the past decade. With an ageing population and an increasing proportion of healthcare-associated IE, the epidemiology of IE has undergone significant changes. Staphylococcus aureus has evolved as the most common causative microorganism, even in most low- and middle-income countries. Several imaging modalities and novel microbiological tests have emerged to facilitate the diagnosis of IE. Outpatient parenteral antibiotic treatment and oral step-down antibiotic treatment have become new trends for the management of IE. Early surgical intervention, particularly within seven days, should be considered in cases of IE with appropriate surgical indications. We comprehensively review the updated epidemiology, microbiology, diagnosis, and management of IE.

Rare post-operative intracranial abscess due to Serratia marcescens: what we can learn from it?

BACKGROUND

Nosocomial infections caused by Serratia marcescens mostly occurred in pediatrics and it was very rarely reported after adult surgery. Here, an intracranial abscess caused by Serratia marcescens was reported. We report a rare case of a postoperative intracranial abscess caused by Serratia marcescens in a 63-year-old male patient with a left parietal mass. The patient underwent resection of the mass on June 1, 2022, and the postoperative pathology revealed an angiomatous meningioma, WHO I. He then experienced recurrent worsening of right limb movements, and repeated cranial CT scans showed oozing blood and obvious low-density shadows around the operation area. Delayed wound healing was considered. Subsequently, a large amount of pus was extracted from the wound. The etiological test showed that Serratia marcescens infection occurred before the removal of the artificial titanium mesh. Antibiotics were initiated based on the results of drug susceptibility tests. At present, the patient is recovering well and is still closely monitored during follow-up.

CONCLUSION

It is rare for Serratia marcescens to cause brain abscesses without any obvious signs of infection. This report provided in detail our experience of a warning postoperative asymptomatic brain abscess caused by an uncommon pathogen.

Cobalt and Chromium Ions Impair Macrophage Response to Staphylococcus aureus Infection

Cobalt-chromium-molybdenum (CoCrMo) alloys are routinely used in arthroplasty. CoCrMo wear particles and ions derived from arthroplasty implants lead to macrophage-driven adverse local tissue reactions, which have been linked to an increased risk of periprosthetic joint infection after revision arthroplasty. While metal-induced cytotoxicity is well characterized in human macrophages, direct effects on their functionality have remained elusive. Synchrotron radiation X-ray microtomography and X-ray fluorescence mapping indicated that peri-implant tissues harvested during aseptic revision of different arthroplasty implants are exposed to Co and Cr in situ. Confocal laser scanning microscopy revealed that macrophage influx is predominant in patient tissue. While in vitro exposure to Cr3+ had only minor effects on monocytes/macrophage phenotype, pathologic concentrations of Co2+ significantly impaired both, monocyte/macrophage phenotype and functionality. High concentrations of Co2+ led to a shift in macrophage subsets and loss of surface markers, including CD14 and CD16. Both Co2+ and Cr3+ impaired macrophage responses to Staphylococcus aureus infection, and particularly, Co2+-exposed macrophages showed decreased phagocytic activity. These findings demonstrate the immunosuppressive effects of locally elevated metal ions on the innate immune response and support further investigations, including studies exploring whether Co2+ and Cr3+ or CoCrMo alloys per se expose the patients to a higher risk of infections post-revision arthroplasty.

Incidence, antimicrobial resistance and mortality of Pseudomonas aeruginosa bloodstream infections among hospitalized patients in China: a retrospective observational multicenter cohort study from 2017 to 2021

Background

Pseudomonas aeruginosa (P. aeruginosa) accounts for high antimicrobial resistance and mortality rates of bloodstream infections (BSIs). We aim to investigate incidence, antimicrobial resistance and risk factors for mortality of P. aeruginosa BSIs among inpatients.

Methods

A retrospective cohort study were conducted at two tertiary hospitals in 2017-2021. Medical and laboratory records of all inpatients diagnosed with P. aeruginosa BSIs were reviewed. A generalized linear mixed model was used to identify risk factors for mortality.

Results

A total of 285 patients with P. aeruginosa BSIs were identified. Incidence of P. aeruginosa BSIs fluctuated between 2.37 and 3.51 per 100,000 patient-days over the study period. Out of 285 P. aeruginosa isolates, 97 (34.04%) were carbapenem-resistant (CR) and 75 (26.32%) were multidrug-resistant (MDR). These isolates showed low resistance to aminoglycosides (9.51-11.62%), broad-spectrum cephalosporins (17.19-17.61%), fluoroquinolones (17.25-19.43%), and polymyxin B (1.69%). The crude 30-day mortality rate was 17.89% (51/285). Healthcare costs of patients with MDR/CR isolates were significantly higher than those of patients with non-MDR/CR isolates (P < 0.001/=0.002). Inappropriate definitive therapy [adjusted odds ratio (aOR) 4.47, 95% confidence interval (95% CI) 1.35-14.77; P = 0.014], ICU stay (aOR 2.89, 95% CI: 1.26-6.63; P = 0.012) and corticosteroids use (aOR 2.89, 95% CI: 1.31-6.41; P = 0.009) were independently associated with 30-day mortality.

Conclusion

Incidence of P. aeruginosa BSIs showed an upward trend during 2017-2020 but dropped in 2021. MDR/CR P. aeruginosa BSIs are associated with higher healthcare costs. Awareness is required that patients with inappropriate definitive antimicrobial therapy, ICU stay and corticosteroids use are at higher risk of death from P. aeruginosa BSIs.

HIV Infection impairs the Host Response to Mycobacterium tuberculosis Infection by altering Surfactant Protein D function in the Human Lung Alveolar Mucosa

Tuberculosis is the leading cause of death for people living with HIV (PLWH). We hypothesized that altered functions of innate immune components in the human alveolar lining fluid of PLWH (HIV-ALF), drive susceptibility to Mycobacterium tuberculosis (M.tb) infection. Our results indicate a significant increase in oxidation of innate proteins and chemokine levels, and significantly lower levels and function of complement components and Th1/Th2/Th17 cytokines in HIV-ALF vs. control-ALF (non-HIV infected people). We further found a deficiency of surfactant protein-D (SP-D) and reduced binding of SP-D to M.tb that had been exposed to HIV-ALF. Primary human macrophages infected with M.tb exposed to HIV-ALF were significantly less capable of controlling the infection, which was reversed by SP-D replenishment in HIV-ALF. Thus, based on the limited number of participants in this study, our data suggest that PLWH without antiretroviral therapy (ART) have declining host innate defense function in their lung mucosa, thereby favoring M.tb and potentially other pulmonary infections.

Co-Occurrence of Gram-Negative Rods in Patients with Hematologic Malignancy and Sinopulmonary Mucormycosis

Both Mucorales and Gram-negative rods (GNRs) commonly infect patients with hematological malignancies (HM); however, their co-occurrence is understudied. Therefore, we retrospectively reviewed the records of 63 patients with HM and proven or probable sinopulmonary mucormycosis at MD Anderson Cancer Center (Houston, Texas) from 2000-2020. Seventeen out of sixty-three reviewed patients (27.0%) had sinopulmonary co-occurrence of GNRs (most commonly Pseudomonas aeruginosa and Stenotrophomonas maltophilia) within 30 days of a positive Mucorales culture or histology demonstrating Mucorales species. Eight of seventeen co-isolations of Mucorales and GNRs were found in same-day samples. All 15 patients with GNR co-occurrence and reported antimicrobial data had received anti-Pseudomonal agents within 14 days prior to diagnosis of mucormycosis and 5/15 (33.3%) had received anti-Stenotrophomonal agents. Demographic and clinical characteristics of patients with and without GNR co-occurrence were comparable. Forty-two-day all-cause mortality was high (34.9%) and comparable in patients with (41.2%) and without (32.6%) GNR detection (p = 0.53). In summary, over a quarter of heavily immunosuppressed patients with sinopulmonary mucormycosis harbored GNRs in their respiratory tract. Although no impact on survival outcomes was seen in a background of high mortality in our relatively underpowered study, pathogenesis studies are needed to understand the mutualistic interplay of GNR and Mucorales and their influence on host responses.

Validation of a Classification System for Optimal Application of Debridement, Antibiotics, and Implant Retention in Prosthetic Joint Infections following Total Knee Arthroplasty: A Retrospective Review

INTRODUCTION

Periprosthetic joint infection (PJI) remains a serious complication after total knee arthroplasty (TKA). While debridement, antibiotics, and implant retention (DAIR) are considered for acute PJI, success rates vary. This study aims to assess a new scoring system's accuracy in predicting DAIR success.

METHODS

119 TKA patients (2008-2019) diagnosed with PJI who underwent DAIR were included for analysis. Data were collected on demographics, laboratory values, and clinical outcomes. This was used for validation of the novel classification system consisting of PJI acuteness, microorganism classification, and host health for DAIR indication. Statistical analysis was carried out using SPSS programming.

RESULTS

Mean follow-up was 2.5 years with an average age of 65.5 ± 9.1 years, BMI of 31.9 ± 6.2 kg/m2, and CCI of 3.04 ± 1.8. Successful infection eradication occurred in 75.6% of patients. The classification system demonstrated 61.1% sensitivity, 72.4% specificity, and 87.3% positive predictive value (PPV) when the DAIR cutoff was a score less than 6. For a cutoff of less than 8, sensitivity was 100%, specificity was 37.9%, and PPV was 83.3%.

CONCLUSIONS

To date, no consensus exists on a classification system predicting DAIR success. This novel scoring system, with high PPV, shows promise. Further refinement is essential for enhanced predictive accuracy.

Incidence of acute kidney injury (AKI) and its impact on patient outcomes among adult hospitalized patients with carbapenem-resistant Gram-negative infections who received targeted treatment with a newer β-lactam or β-lactam/β-lactamase inhibitor-, polymyxin- or aminoglycoside-containing regimen

BACKGROUND

Limited comparative data exist on acute kidney injury (AKI) risk and AKI-associated outcomes in hospitalized patients with carbapenem-resistant Gram-negative infections (CR-GNIs) treated with a newer β-lactam/β-lactam-β-lactamase inhibitor (BL/BL-BLI)-, polymyxin (PB)- or aminoglycoside (AG)-containing regimen. This study quantified the risk of AKI and AKI-related outcomes among patients with CR-GNIs treated with a newer BL/BL-BLI-, PB- or AG-containing regimen.

METHODS

A multicentre, retrospective, observational study was performed (2016-20). The study included adult hospitalized patients with (i) baseline estimated glomerular filtration rates ≥30 mL/min/1.73 m2; (ii) CR-GN pneumonia, complicated urinary tract infection or bloodstream infection; and (iii) receipt of newer BL/BL-BLI, PG or AG within 7 days of index CR-GN culture for ≥3 days. Outcomes included AKI, in-hospital mortality and hospital costs.

RESULTS

The study included 750 patients and most (48%) received a newer BL/BL-BLI. The median (IQR) treatment duration was 8 (5-11), 5 (4-8) and 7 (4-8) days in the newer BL/BL-BLI group, AG group and PB group, respectively. The PB group had the highest adjusted AKI incidence (95% CI) (PB: 25.1% (15.6%-34.6%) versus AG: 8.9% (5.7%-12.2%) versus newer BL/BL-BLI: 11.9% (8.1%-15.7%); P = 0.001). Patients with AKI had significantly higher in-hospital mortality (AKI: 18.5% versus 'No AKI': 5.6%; P = 0.001) and mean hospital costs (AKI: $49 192 versus 'No AKI': $38,763; P = 0.043).

CONCLUSIONS

The AKI incidence was highest among PB patients and patients with AKI had worse outcomes. Healthcare systems should consider minimizing the use of antibiotics that augment AKI risk as a measure to improve outcomes in patients with CR-GNIs.

Polyclonal anti-whole cell IgY passive immunotherapy shields against P. aeruginosa-induced acute pneumonia and burn wound infections in murine models

Pseudomonas aeruginosa (PA) is a multidrug-resistant (MDR) opportunistic pathogen causing severe hospital-, and community-acquired infections worldwide. Thus, the development of effective immunotherapy-based treatments is essential to combat the MDR-PA infections. In the current study, we evaluated the protective efficacy of polyclonal avian antibodies raised against inactivated whole cells of the PAO1 strain in murine models of acute pneumonia and burn wound. The efficacy of generated antibodies was evaluated against different PA strains through several in vitro, ex vivo and in vivo experiments. The results showed that the anti-PAO1-IgY effectively reduced the motility, biofilm formation and cell internalization ability, and enhanced the opsonophagocytic killing of PA strains through the formation of immobilized bacteria and induction of increased cell surface hydrophobicity. Furthermore, immunotherapy with anti-PAO1-IgY completely protected mice against all PA strains in both acute pneumonia and burn wound murine models. It was found to reduce the bacterial loads in infected burned mice through interfering with virulence factors that play vital roles in the early stages of PA infection, such as colonization and cell internalization. The immunotherapy with anti-PAO1-IgYs could be instrumental in developing effective therapies aimed at reducing the morbidity and mortality associated with PA infections.

Comparative analysis of infective endocarditis in hemodialysis versus non-hemodialysis patients in Iran: implications for clinical practice and future research

BACKGROUND

In hemodialysis (HD) patients, there is a larger frequency of mortality and morbidity associated with infective endocarditis (IE) as opposed to the general population. Despite the increased burden of IE in the HD population, optimal strategies for prevention and management still need to be clarified. Elucidating the distinguishing features and outcomes of IE in HD patients is crucial to guide clinical decision-making and improve prognosis in this high-risk group. However, the details of IE characteristics, specifically in HD patients in the Middle East, are limited.

OBJECTIVE

To compare the clinical characteristics and short-term outcomes of IE between HD and non-HD patients.

METHODS

A retrospective analysis was carried out on 139 patients with infective endocarditis who were referred to a tertiary cardiovascular center in Iran from 2006 to 2018. The participants were split into HD (n = 34) and non-HD (n = 105) groups. Data pertaining to demographic characteristics, comorbidities, microbiological findings, occurrence of complications, therapeutic interventions, and mortality rates during hospital stay were gathered.

RESULTS

Diabetes, hypertension, and congestive heart failure were observed more frequently in HD patients. HD patients were more likely than non-HD patients to have involvement of the right valve (41.2% vs. 20.9%), larger vegetation, and extracardiac emboli. In-hospital mortality was 41.2% for HD patients versus 14.3% for non-HD patients. Mortality remained high after valve surgery in HD patients (38.2% vs. 10.5% in non-HD).

CONCLUSION

HD patients exhibited a distinct clinical profile of IE with worse short-term outcomes, including higher mortality.

Environmental impacts of 5-year plastic waste deposition on municipal waste landfills: A follow-up study

Depositing plastic waste has long been a prevalent method of utilization, persisting today. Plastic waste within municipal waste landfills (MWL) undergoes diverse (bio-)degradation processes, which may be a potential source of chemicals and microorganisms harmful to the environment and human health. Soil and air samples were collected from modern MWL to identify environmental contamination caused by 5 years of plastic (bio-)degradation. The pH of soil samples was higher than in the reference area (RA), which was possibly caused by alterations in soil anionic composition detected with ion chromatography. The presence of plastic additives with a toxic potential was detected in soil samples by gas chromatography coupled with tandem mass spectrometry (GC-MS/MS). With the use of thermal desorption and GC - MS, hazardous substances (phthalic anhydride, phenylmaleic anhydride, ethylbenzene, xylene) with a known impact on the human endocrine system were also detected. The number of microorganisms, both fungi, and bacteria, was highly increased in soil and air in the MWL as compared to the RA. The soil collected in the MWL area appeared to be phytotoxic, and inhibited seed germination (Phytotoxkit FTM bioassay), while acute toxicity Microtox® bioassay showed a hormetic effect towards Aliivibrio fischeri. Obtained results exhibited massive soil and air contamination, with both chemical substances and microorganisms while plastic waste undergoes (bio-)degradation. It may contribute to serious environmental contamination and pose a threat to human health.

Clinical significance of mutations in dihydropteroate synthase in Pneumocystis jirovecii pneumonia among non-HIV-infected patients

BACKGROUND

Dihydropteroate synthase (DHPS) mutations may be associated with trimethoprim-sulfamethoxazole resistance in Pneumocystis jirovecii pneumonia (PCP) and worse clinical outcomes. However, the clinical significance of DHPS mutations in PCP among non-human immunodeficiency virus (HIV)-infected patients remains unclear.

METHODS

Patients with PCP in three tertiary referral hospitals in Taiwan between 2016 and 2020 were retrospectively enrolled. Two point mutations, Thr55Ala and Pro57Ser, in the DHPS protein were analysed. Patients with invalid DHPS mutations in the respiratory specimen, chronic respiratory failure, receiving endotracheal intubation for surgical intervention, HIV infection, Pneumocystis jirovecii colonisation, and no lactate dehydrogenase (LDH) data were excluded. The primary outcome was 30-day survival.

RESULTS

A total of 215 patients were analysed. Mutants inside DHPS were found in 78 patients (36.3%) and 68 patients (31.6%) died within 30 days. A total of 214 patients (99.5%) received trimethoprim-sulfamethoxazole as the first-line treatment. The rates of mechanical ventilation, 30-day, and in-hospital mortality were similar between wild-type and mutant DHPS PCP. After adjusting for important confounders, LDH > 500 µ/L (adjusted hazard ratio [aHR] = 2.448, P = 0.001), pneumonia severity index > 135 mg/dL (aHR = 1.689, P = 0.049), and having solid tumours (aHR = 1.832, P = 0.034) were independently associated with higher mortality. In subgroup analysis, mutant DHPS PCP patients had less 30-day mortality among patients aged > 65 years (P = 0.049), with lymphopenia (P = 0.040), and those without solid tumour (P = 0.045).

CONCLUSIONS

In non-HIV-infected PCP, point mutants inside DHPS may not be associated with trimethoprim-sulfamethoxazole treatment outcomes. Further prospective large-scale studies are warranted.

A Case of Infective Endocarditis Caused by Citrobacter koseri: Unraveling a Rare Pathogen and Dire Outcome

Citrobacter koseri (formerly classified as Citrobacter diversus) is a gram-negative bacillus (GNB) that occurs as an opportunistic pathogen in neonates and immunocompromised patients. Citrobacter species have been implicated in nosocomial settings leading to infections involving the urinary tract, respiratory tract, liver, biliary tract, meninges, and even in rarer conditions-blood stream infection and infective endocarditis (IE). Gram-negative bacilli are responsible for 3% to 4% of all IE cases and have been traditionally associated with intravenous drug users. Patients with non-HACEK (species other than Haemophilus species, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, or Kinglella species) GNB IE have poor clinical outcomes with higher rates of in-hospital mortality and complications. The American Heart Association (AHA) and Infectious Diseases Society of America (IDSA) both recommend the use of combination antibiotic therapy with a beta-lactam (penicillins, cephalosporins, or carbapenems) and either an aminoglycoside or fluoroquinolones for 6 weeks (about 1 and a half months) to treat IE due to non-HACEK GNB. Citrobacter koseri is becoming more recognized due to its inherent resistance to ampicillin and emerging drug resistance to beta lactams and aminoglycosides requiring carbapenem therapy. Our case is of a 75-year-old male with no previously reported history of primary or secondary immunodeficiency disorders who developed C koseri blood stream infection. His infectious work-up revealed mitral valve IE and septic cerebral emboli resulting in ischemic infarcts. This case illustrates the importance of recognizing GNB organisms as rising human pathogens in IE cases even without active injection drug use or nosocomial exposure.

Fluoroquinolone resistance in urinary tract infections: Epidemiology, mechanisms of action and management strategies

Background

Fluoroquinolone resistance is an issue of concern amongst physicians worldwide. In urology, fluoroquinolones are often used in the treatment of acute pyelonephritis and prostatitis, as well as infections caused by multidrug-resistant pathogens.

Aims

We aim to highlight the importance of antimicrobial stewardship and the need for ongoing biomedical research to discover novel agents in our losing battle against resistant pathogens.

Materials and methods

In this review, we survey the literature and summarise fluoroquinolone resistance as it pertains to pyelonephritis and prostatitis, as well as alternative treatment strategies and prevention of multidrug resistance.

Results

The rise of fluoroquinolone resistance in bacteria has reduced the available treatment options, often necessitating hospital admission for intravenous antibiotics, which places an additional burden on both patients and the healthcare system. Many countries such as Australia have attempted to limit fluoroquinolone resistance by imposing strict prescribing criteria, though these efforts have not been entirely successful. Solutions to overcome resistance include prevention, combination therapy and the development of novel antimicrobial agents.

Conclusions

Prevention of the proliferation of resistant organisms by antimicrobial stewardship is paramount, and urologists are obliged to be aware of responsible prescribing practices such as referring to local guidelines when prescribing. By reserving fluoroquinolones for infections in which they are truly indicated and by prescribing based on both patient and local environmental factors, we can preserve this effective resource for future use.

Acute kidney injury associated with colistin sulfate vs. polymyxin B sulfate therapy: A real-world, retrospective cohort study

OBJECTIVE

To compare the incidence of acute kidney injury (AKI) in patients treated with colistin sulfate (CS) and polymyxin B sulfate (PMB).

METHODS

Sociodemographic and laboratory measures of adult patients who received intravenous CS or PMB for at least 72 h for the first time at the study hospital from October 2021 to November 2022 were collected retrospectively. The primary outcome was the incidence of AKI, defined by the Kidney Diseases Improving Global Outcomes criteria. The secondary outcome was 30-day mortality.

RESULTS

In total, 109 patients were included in the CS cohort and 176 patients were included in the PMB cohort. The incidence of AKI was significantly higher in the PMB cohort compared with the CS cohort (50.6% vs. 18.3%; P<0.001). On multi-variate analysis, CS therapy [hazard ratio (HR) 0.275; P<0.001] was an independent protective factor for AKI, along with higher estimated glomerular filtration rate. Nevertheless, 30-day mortality was similar in the PMB and CS cohorts (21.6% vs. 13.8%; P=0.099). Multi-variate analyses revealed that CS therapy was not associated with 30-day mortality (HR 0.968; P=0.926), while intensive care unit admission, combination with meropenem, Charlson score and stage 3 AKI were independent risk factors for 30-day mortality. After balancing the baseline characteristics of patients using propensity score matching, the main results were unchanged.

CONCLUSION

The incidence of AKI was significantly lower in the CS cohort compared with the PMB cohort. However, 30-day mortality was similar in the two cohorts.

In-hospital care of children with COVID-19

Children have been reported to be less affected and to have milder severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection than adults during the coronavirus disease 2019 (COVID-19) pandemic. However, children, and particularly those with underlying disorders, are still likely to develop critical illnesses. In the case of SARS-CoV-2 infection, most previous studies have focused on adult patients. To aid in the knowledge of in-hospital care of children with COVID-19, this study presents an expert review of the literature, including the management of respiratory distress or failure, extracorporeal membrane oxygenation (ECMO), multisystem inflammatory syndrome in children (MIS-C), hemodynamic and other organ support, pharmaceutical therapies (anti-viral drugs, anti-inflammatory or antithrombotic therapies) and management of cardiopulmonary arrest.

Two-Stage Treatment Protocol of Fungal Periprosthetic Hip and Knee Joint Infections: the Clinical Experience from a Single Center Experience

PURPOSE OF THE STUDY

To evaluate the clinical results and safety of fungal periprosthetic joint Infections (fPJIs) using two-stage treatment protocol.

MATERIAL AND METHODS

8 patients with fPJIs (3 hips and 5 knees) using two-stage revision were reviewed retrospectively and followed up at least 2 years. The preoperative demographic data, two-stage treatment protocol, results of microbiology and histologic workup and postoperative follow-up results (reimplantation success rate and infection free time) were recorded.

RESULTS

7 patients got successful reimplantation, with a 75% reimplantation success rate. Two patients got knee arthrodesis eventually. All patients were infection free with a median follow-up of 4.0 ± 2.0 years (range, 2-7 years). Of them, Candida species were found in 7 patients, while non-Candida specimen was only isolated in 1 patient with Aspergillus. Only 2 patients had coexisting bacterial infection (Methicillin-resistant coagulase-negative Staphylococci and Proteus mirabilis respectively). The average interval between the initial surgery and diagnosis of fPJIs was 21.50±34.79 months (range, 4-104 months). The mean time of spacer implantation was 7.75±2.77 months (range, 6-14 months). None serious complication or above knee amputation was found.

DISCUSSION

fPJIs are very rare and considerable challenge after total hip or knee arthroplasty. The goal of therapy is to eradicate local infection and maintain function. Candida species were the most common pathogen. The duration between spacer placement and staged reimplantation was highly variable, and generally dependent upon the results of joint aspirates and infl ammatory markers. The current study shows that the two-stage treatment protocol is recommended for fungal periprosthetic hip and knee joint infections.

CONCLUSIONS

The two-stage treatment protocol is recommended for fungal periprosthetic hip and knee joint infections. The safety and effi cacy of biantibiotical impregnated (antifungal + antibiotics) cement spacer is confi rmed. Further evidence-based work is needed to determine the optimal drug dose and reimplantation time.

KEY WORDS

two-stage treatment protocol, fungal periprosthetic infections, hip spacer, knee spacer.

Mitral valve surgery in acute infective endocarditis: long-term outcomes of mitral valve repair versus replacement

AIMS

Timing and surgical strategies in acute infective endocarditis are still questionable. We sought to investigate clinical outcomes of patients undergoing mitral valve repair (MVR) compared with mitral valve replacement [mitral valve prosthesis (MVP)] for acute infective endocarditis.

METHODS

From 2004 to 2019, 109 consecutive patients with acute mitral valve infective endocarditis were retrospectively investigated. Patients were divided into two groups according to surgical strategy: MVR 53/109 (48.6%) versus MVP 56/109 (51.4%). Primary end points were in-hospital mortality and overall survival at 10 years. Secondary end point was the freedom from infective endocarditis relapse.

RESULTS

Our institutional surgical approach for infective endocarditis allowed us to achieve MVR in 48.6% of patients. Hospital mortality was comparable between the two groups [MVR: 1/53 (1.9%) versus MVP: 2/56 (3.6%), P  = 1.000]. Overall 10-year survival was 80.0 ± 14.1 and 77.2 ± 13.5% for MVR and MVP, respectively ( P  = 0.648). MVR showed a lower incidence of infective endocarditis relapse compared with MVP (MVR: 93.6 ± 7.1 versus MVP: 80.9 ± 10.8%, P  = 0.041). At Cox regression, infective endocarditis relapse was an independent risk factor for death (hazard ratio 4.03; 95% confidence interval 1.41-11.52; P  = 0.009).

CONCLUSION

The tendency to postpone surgery in stable patients with mitral infective endocarditis allowed achievement of MVR in almost 50% of patients. Although repair remains the approach of choice in our institution, no differences between MVR and MVP were reported in terms of early/late survival. However, MVP had a higher incidence of infective endocarditis relapse that represents an independent risk of mortality.

Clinical outcomes of rifampicin combination therapy in implant-associated infections due to staphylococci and streptococci: A systematic review and meta-analysis

OBJECTIVES

Adjunctive rifampicin for implant-associated infections is controversial. This study investigated the clinical outcomes of rifampicin combination therapy compared with monotherapy in treating prosthetic joint infection (PJI) or prosthetic valve endocarditis (PVE) due to staphylococci and streptococci.

METHODS

A systematic search was performed from inception to 13 June 2022 in Embase, MEDLINE, Cochrane and Web of Science to investigate the clinical outcomes of rifampicin combination therapy compared with monotherapy in treating staphylococcal and streptococcal PJI or PVE. Randomised controlled trials (RCTs) and observational studies were included in the systematic review and meta-analysis.

RESULTS

Fourteen studies were included. A moderate quality of evidence was found in favour of rifampicin in patients with staphylococcal PJI who underwent a debridement, antibiotics and implant retention (DAIR) procedure [odds ratio = 2.49, 95% confidence interval (CI) 1.93-3.23]. Including the two RCTs only, adding rifampicin to the antibiotic regimen after DAIR was also in favour of rifampicin, but this was not statistically significant (risk ratio = 1.27, 95% CI 0.79-2.04; n = 126). Pooling data for patients with staphylococcal PJI who underwent a two-stage procedure showed that adding rifampicin was not associated with therapeutic success. Limited evidence was found for the use of rifampicin for PVE caused by staphylococci.

CONCLUSIONS

Adding rifampicin in the treatment of staphylococcal PJI treated by DAIR clearly increased the likelihood for therapeutic success. The clinical benefit of adjunctive rifampicin in the treatment of other staphylococci and streptococci implant-associated infections is still unclear.

Factors Related to the Development of Infective Endocarditis in Hemodialysis Patients in a Third-Level Hospital in Panama

INTRODUCTION

Venous access for hemodialysis (HD) makes patients more susceptible to transient bacteremia, predisposing them to the development of infective endocarditis (IE). Among the risk factors observed in this population are temporary access to HD, hypoalbuminemia, diabetes mellitus, female gender, anemia, and colonization by methicillin-resistant Staphylococcus aureus (MRSA).

METHODOLOGY

A retrospective case-control study with a one-to-two ratio was carried out on patients with chronic kidney disease (CKD) undergoing renal replacement therapy with at least one vascular access for HD at Complejo Hospitalario Dr. Arnulfo Arias Madrid (CHDrAAM) from 2010 to 2020. Sociodemographic variables, past medical history, and data on current HD were studied. The odds ratio (OR) and adjusted odds ratio (aOR) were calculated for the collected variables.

RESULTS

No statistically significant differences between the groups were observed in sociodemographic variables. In terms of past medical history, the cases showed a predominance of coronary disease (47.6% vs 4.8%; OR: 37.27), valvular disease (23.8% vs 0%), and heart failure (33.3% vs 4.8%; OR: 10). In the cases, the use of a temporary catheter was more prevalent (61.9% vs 33.3%; OR: 3.25), and subclavian access was more frequently recorded (28.6% vs 2.4%; OR: 14.4). A short duration of venous access (<30 days) was found in a greater proportion of cases (23.8% vs 4.8%; OR: 6.25). The main pathogen isolated was S. aureus (33.3%), and the most affected valve was the aortic valve (59.1%). Fever was found in 100% of the reported cases, and up to 47.6% presented with a recent murmur.

DISCUSSION

Similar to previous studies conducted in other countries, we identified a history of pre-existing valve disease, the use of a temporary catheter, and recent venous access as risk factors. Contrary to what has been reported in the literature, this study did not find female sex, diabetes mellitus, and hypoalbuminemia as risks.

CONCLUSION

Factors such as a history of coronary artery disease, heart failure, preexisting valvular disease, the use of a temporary catheter, subclavian venous access, and short duration of venous access (<30 days) were identified as risk factors for the development of IE in patients with CKD on HD.