Treatment and outcomes in carbapenem-resistant Klebsiella pneumoniae bloodstream infections

Analysis of the Association Between Antimicrobial Resistance Genes and Virulence Factors in ST11 and Non-ST11 CR-KP Bloodstream Infections in the Intensive Care Unit

Objective

This study aims to investigate the association between antimicrobial resistance genes and virulence factors in ST11 and non-ST11 types of CR-KP in bloodstream infections in the intensive care unit, providing a theoretical basis for infection control and clinical diagnosis and treatment.

Methods

From January 2021 to June 2023, samples of Klebsiella pneumoniae from bloodstream infections were collected at our hospital, focusing on those resistant to carbapenems. The resistance genes, housekeeping genes, and virulence genes were identified through PCR and analyzed using the GrapeTree software to perform MLST-based minimum spanning tree typing.

Results

Among the 85 CR-KP cases, 61.18% were of the ST11 type, predominantly of the KL64 capsular type; non-ST11 types were mainly ST15, accounting for 25.88%, predominantly of the KL5 capsular type. The carriage rates of virulence genes such as rmpA2, entB, silS, kpn, iucA, peg-344, and terB were significantly higher in the ST11 group than in the non-ST11 group. The primary carbapenemase identified was class A enzyme bla KPC-2, with a higher carriage rate in the ST11 group. Drug susceptibility tests showed that the resistance rates for cefepime, ertapenem, nitrofurantoin, amikacin, and gentamicin were also higher in the ST11 group, consistent with the resistance genotype findings.

Conclusion

The study reveals that ST11 type CR-KP in intensive care unit bloodstream infections exhibits stronger resistance and higher virulence compared to non-ST11 types, posing significant challenges to clinical treatment. Thus, strict control over the use of carbapenem antibiotics is essential to prevent the spread of resistant plasmids.

Pharmacokinetics of polymyxin B in different populations: a systematic review

BACKGROUND AND OBJECTIVES

Despite being clinically utilized for the treatment of infections, the limited therapeutic range of polymyxin B (PMB), along with considerable interpatient variability in its pharmacokinetics and frequent occurrence of acute kidney injury, has significantly hindered its widespread utilization. Recent research on the population pharmacokinetics of PMB has provided valuable insights. This study aims to review relevant literature to establish a theoretical foundation for individualized clinical management.

METHODS

Follow PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, Pop-PK studies of PMB were searched in PubMed and EMBASE database systems from the inception of the database until March 2023.

RESULT

To date, a total of 22 population-based studies have been conducted, encompassing 756 subjects across six different countries. The recruited population in these studies consisted of critically infected individuals with multidrug-resistant bacteria, patients with varying renal functions, those with cystic fibrosis, kidney or lung transplant recipients, patients undergoing extracorporeal membrane oxygenation (ECMO) or continuous renal replacement therapy (CRRT), as well as individuals with obesity or pediatric populations. Among these studies, seven employed a one-compartmental model, with the range of typical clearance (CL) and volume (Vc) being 1.18-2.5L /h and 12.09-47.2 L, respectively. Fifteen studies employed a two-compartmental model, with the ranges of the clearance (CL) and volume of the central compartment (Vc), the volume of the peripheral compartment (Vp), and the intercompartment clearance (Q) were 1.27-8.65 L/h, 5.47-38.6 L, 4.52-174.69 L, and 1.34-24.3 L/h, respectively. Primary covariates identified in these studies included creatinine clearance and body weight, while other covariates considered were CRRT, albumin, age, and SOFA scores. Internal evaluation was conducted in 19 studies, with only one study being externally validated using an independent external dataset.

CONCLUSION

We conclude that small sample sizes, lack of multicentre collaboration, and patient homogeneity are the primary reasons for the discrepancies in the results of the current studies. In addition, most of the studies limited in the internal evaluation, which confined the implementation of model-informed precision dosing strategies.

The Clinical Efficacy of Adding Ceftazidime/Avibactam to Standard Therapy in Treating Infections Caused by Carbapenem-Resistant Klebsiella pneumonia with blaOXA-48-like Genes

Ceftazidime/avibactam (CAZ-AVI) is FDA-approved for managing infections caused by resistant gram-negative bacilli, particularly infections via carbapenem-resistant Enterobacterales pathogens. The clinical data are still limited, particularly those in Saudi Arabia. The present study is a retrospective cohort study that was carried out at the Armed Forces Hospital in the southern region of Saudi Arabia to compare the clinical and microbiological outcomes for CAZ-AVI-treated patients as monotherapy and as an add-on to standard therapy for carbapenem-resistant Klebsiella pneumonia (CRKP) OXA-48 infections to those treated with standard drugs. The study included CRKP OXA-48-like infected patients who were administered antibiotics for more than seven days from 1 August 2018 to May 2023. Patients' baseline characteristics and demography were extracted from the clinical records, and their clinical/microbiology efficiencies were assessed as per the corresponding definitions. Univariate and multivariate logistic regressions were conducted to identify the potential independent variable for CAZ-AVI efficiency. A total of 114 patient files were included for the evaluation. Among these patients, 64 used CAZ-AVI combined with standard therapy and were included in the intervention group, and 50 of them used standard therapy and were included in the comparative group. Following analysis, CAZ-AVI's clinical success was 42.2% (p = 0.028), while the intervention versus comparative groups showed decreased 30-day all-cause mortality (50.0% versus 70.0%; p = 0.036) and infection recurrence (7.8% versus 24.0%; p = 0.019), as well as substantially increased rates of microbial eradication (68.8% versus 42.0%; p = 0.007). CAZ-AVI add-on therapy rather than monotherapy showed statistically significant favored clinical and microbial outcomes over the standard therapy. Furthermore, sex (female %), ICU admission, and fever were negatively associated with patients' 30-day all-cause mortality, serving as independent negative factors. Only fever, CRP bio levels, inotropes, and ICU admissions were significant predictors influencing the CAZ-AVI's clinical efficiency. The duration of CAZ-AVI therapy positively influenced CAZ-AVI's microbial eradication, while both WBC counts and fever experiences were negative predictors. This study shows the effective usage of CAZ-AVI against CRKP OXA-48-like infections. The influencing independent variables depicted here should recommend that clinicians individualize the CAZ-AVI dose based on co-existing risk factors to achieve optimal survival and efficacy. Prospective multicenter and randomized control studies are recommended, with individualized CAZ-AVI precision administration implemented based on patients' characteristics.

Predicting Risk of Multidrug-Resistant Enterobacterales Infections Among People With HIV

Background

Medically vulnerable individuals are at increased risk of acquiring multidrug-resistant Enterobacterales (MDR-E) infections. People with HIV (PWH) experience a greater burden of comorbidities and may be more susceptible to MDR-E due to HIV-specific factors.

Methods

We performed an observational study of PWH participating in an HIV clinical cohort and engaged in care at a tertiary care center in the Southeastern United States from 2000 to 2018. We evaluated demographic and clinical predictors of MDR-E by estimating prevalence ratios (PRs) and employing machine learning classification algorithms. In addition, we created a predictive model to estimate risk of MDR-E among PWH using a machine learning approach.

Results

Among 4734 study participants, MDR-E was isolated from 1.6% (95% CI, 1.2%-2.1%). In unadjusted analyses, MDR-E was strongly associated with nadir CD4 cell count ≤200 cells/mm³ (PR, 4.0; 95% CI, 2.3-7.4), history of an AIDS-defining clinical condition (PR, 3.7; 95% CI, 2.3-6.2), and hospital admission in the prior 12 months (PR, 5.0; 95% CI, 3.2-7.9). With all variables included in machine learning algorithms, the most important clinical predictors of MDR-E were hospitalization, history of renal disease, history of an AIDS-defining clinical condition, CD4 cell count nadir ≤200 cells/mm³, and current CD4 cell count 201-500 cells/mm³. Female gender was the most important demographic predictor.

Conclusions

PWH are at risk for MDR-E infection due to HIV-specific factors, in addition to established risk factors. Early HIV diagnosis, linkage to care, and antiretroviral therapy to prevent immunosuppression, comorbidities, and coinfections protect against antimicrobial-resistant bacterial infections.

Cost utility analysis of strategies for minimizing risk of duodenoscope-related infections

BACKGROUND AND AIMS

Transmission of multidrug-resistant organisms by duodenoscopes during ERCP is problematical. The U.S. Food and Drug Administration recently recommended transitioning away from reusable fixed-endcap duodenoscopes to those with innovative device designs that make reprocessing easier, more effective, or unnecessary. Partially disposable (PD) duodenoscopes with disposable endcaps and fully disposable (FD) duodenoscopes are now available. We assessed the relative cost of approaches to minimizing infection transmission, taking into account duodenoscope-transmitted infection cost.

METHODS

We developed a Monte Carlo analysis model in R (R Foundation for Statistical Computing, Vienna, Austria) with a multistate trial framework to assess the cost utility of various approaches: single high-level disinfection (HLD), double HLD, ethylene oxide (EtO) sterilization, culture and hold, PD duodenoscopes, and FD duodenoscopes. We simulated quality-adjusted life years (QALYs) lost by duodenoscope-transmitted infection and factored this into the average cost for each approach.

RESULTS

At infection transmission rates <1%, PD duodenoscopes were most favorable from a cost utility standpoint in our base model. The FD duodenoscope minimizes the potential for infection transmission and is more favorable from a cost utility standpoint than use of reprocessable duodenoscopes after single or double HLD at all infection rates, EtO sterilization for infection rates >.32%, and culture and hold for infection rates >.56%. Accounting for alternate scenarios of variation in hospital volume, QALY value, post-ERCP lifespan, and environmental cost shifted cost utility profiles.

CONCLUSIONS

Our model indicates that PD duodenoscopes represent the most favorable option from a cost utility standpoint for ERCP, with anticipated very low infection transmission rates and a low-cost disposable element. These data underscore the importance of cost calculations that account for the potential for infection transmission and associated patient morbidity/mortality.

The epidemiology of bloodstream infection contributing to mortality: the difference between community-acquired, healthcare-associated, and hospital-acquired infections

BACKGROUND

The epidemiology of bloodstream infection (BSI) is well-established; however, little is known about the contribution of different pathogens to mortality. To understand true burden of BSI, pathogens contributing to mortality were investigated and compared according to where the BSI was acquired.

METHODS

Data from deceased patients in two teaching hospitals in the Republic of Korea were collected. BSI contributing mortality was defined as BSI within 2-weeks before death. Cases were grouped by acquisition sites: community-acquired (CA)-, healthcare-associated (HCA)-, and hospital-acquired (HA)-BSI. Drug resistance, BSI focus, and appropriateness of empirical antimicrobial therapy were also compared.

RESULTS

Among 1849 deceased patients in the hospitals, 280 (15.1%) patients experienced BSI within 2-weeks before death. In all, 71, 53, and 156 patients in the CA-, HCA-, and HA-BSI groups, respectively, with 316 total isolated pathogens were analyzed. The three most common pathogens were Klebsiella pneumoniae (17.1%), Escherichia coli (16.4%), and Staphylococcus aureus (11.4%). While K. pneumoniae and E. coli were the most common pathogens in CA- and HCA-BSI, Acinetobacter baumannii and Candida species were in HA-BSI. 26.3% (41/156) of patients experienced breakthrough HCA-BSI during administration of carbapenem and/or vancomycin. The proportion of central venous catheter-related infection (0%, 3.4% and 28.3%), carbapenem resistant-Gram negative bacilli (0%, 6.9% and 21.9%), and inappropriate empirical antimicrobial therapy (21.1%, 37.7% and 51.9%; all P < 0.001) were more frequently observed in HA-BSI.

CONCLUSION

The epidemiology of BSI related to mortality had unique characteristics according to the acquisition site. Given the epidemiology of HA-BSI, infection control and antibiotics stewardship programs should be emphasized.

The Value of Neutrophil-To-Lymphocyte Ratio for Evaluating Blood Stream Infection Caused by Carbapenem-Resistant Klebsiella pneumoniae: A Retrospective Cohort Study

Background

The neutrophil-to-lymphocyte ratio (NLR) is a useful marker of inflammation. However, the prognostic function of the NLR in patients with carbapenem-resistant Klebsiella pneumoniae (CRKP) blood stream infection (BSI) remains largely unknown. The aim of this study was to explore the potential relationship between the NLR and mortality in these patients.

Methods

We performed a retrospective cohort study based on data retrieved from the computerized patient record system in a tertiary hospital from 1 January 2017 to 31 October, 2020. A total of 134 inpatients with CRKP BSI were enrolled in this study, including 54 fatal cases and 80 survival cases, 28 days after the onset of CRKP BSI. A logistic analysis was performed to assess the association between the NLR on the 4th day and 28-day mortality. Multivariate analyses were used to control for the confounders.

Results

The overall 28-day mortality rate of patients with a CRKP BSI episode was 40.3% (54/134). We conducted a multivariate analysis of the data of 134 patients and found that the NLR on the 4th day [odds ratio (OR) 1.148, 95% confidence interval (CI) 1.076–1.225, p < 0.001] and antibiotic exposure before BSI onset (OR 3.847, 95% CI 1.322–11.196, p = 0.013) were independent risk factors for 28-day mortality of patients with CRKP BSI, while appropriate initial therapy (AIT, OR 0.073, 95% CI 0.017–0.307, p < 0.001) was an independent protective factor. Among patients treated with AITs, the Cox proportional hazards regression analysis revealed a significant difference in prognosis (p = 0.006) between the ceftazidime/avibactam contained (CAZ) group and non CAZ-AVI groups. After dividing the non CAZ-AVI group into the tigecycline (TGC), colistin (COL), and TGC + COL groups, there were no differences between the CAZ-AVI group and the TGC group (p = 0.093), but CAZ-AVI group showed lower 28-day mortality than COL (p = 0.002) and TGC + COL (p = 0.002) groups. Meanwhile, there was no difference in NLR on the 1st day (p = 0.958) of patients in different groups but significant difference in NLR on the 4th day (p = 0.047).

Conclusions

The NLR on the 4th day is a readily available and independent prognostic biomarker for patients with CRKP BSI. This marker may have the potential for use in evaluating the efficacy of different anti-infection therapy strategies at an early stage.

Coupling Machine Learning and High Throughput Multiplex Digital PCR Enables Accurate Detection of Carbapenem-Resistant Genes in Clinical Isolates

Rapid and accurate identification of patients colonised with carbapenemase-producing organisms (CPOs) is essential to adopt prompt prevention measures to reduce the risk of transmission. Recent studies have demonstrated the ability to combine machine learning (ML) algorithms with real-time digital PCR (dPCR) instruments to increase classification accuracy of multiplex PCR assays when using synthetic DNA templates. We sought to determine if this novel methodology could be applied to improve identification of the five major carbapenem-resistant genes in clinical CPO-isolates, which would represent a leap forward in the use of PCR-based data-driven diagnostics for clinical applications. We collected 253 clinical isolates (including 221 CPO-positive samples) and developed a novel 5-plex PCR assay for detection of bla_IMP, bla_KPC, bla_NDM, bla_OXA-48, and bla_VIM. Combining the recently reported ML method “Amplification and Melting Curve Analysis” (AMCA) with the abovementioned multiplex assay, we assessed the performance of the AMCA methodology in detecting these genes. The improved classification accuracy of AMCA relies on the usage of real-time data from a single-fluorescent channel and benefits from the kinetic/thermodynamic information encoded in the thousands of amplification events produced by high throughput real-time dPCR. The 5-plex showed a lower limit of detection of 10 DNA copies per reaction for each primer set and no cross-reactivity with other carbapenemase genes. The AMCA classifier demonstrated excellent predictive performance with 99.6% (CI 97.8–99.9%) accuracy (only one misclassified sample out of the 253, with a total of 160,041 positive amplification events), which represents a 7.9% increase (p-value <0.05) compared to conventional melting curve analysis. This work demonstrates the use of the AMCA method to increase the throughput and performance of state-of-the-art molecular diagnostic platforms, without hardware modifications and additional costs, thus potentially providing substantial clinical utility on screening patients for CPO carriage.

Association between rectal colonization by Klebsiella pneumoniae carbapenemase-producing K. pneumoniae and mortality: a prospective, observational study

BACKGROUND

We evaluated the association of Klebsiella pneumoniae carbapenemase-producing Klebsiella pneumoniae (KPC-Kp) rectal colonization with crude mortality and whether this association is independent of the risk of KPC-Kp infection..

METHODS

Prospective cohort study of patients followed up 90 days after a study of rectal colonization. Cox-regression was used to study the variables associated with crude mortality. Sensitivity analyses for crude 90-day mortality in different subcohorts were performed.

RESULTS

A total of 1244 patients (1078 non-colonized and 166 colonized) were included. None of the non-colonized patients and 78 (47.0%) of the colonized patients developed KPC-Kp infection. Crude 90-day mortality was 18% (194/1078) in non-colonized patients and 41.6% (69/166) in colonized patients. Rectal colonization was not associated with crude mortality (Hazard Ratio [HR] 1.03; 95% CI 0.69-1.54; p = 0.85) when the model was adjusted for severe KPC-Kp infection (INCREMENT-CPE score [ICS] > 7). KPC-Kp infection with ICS > 7 was associated with an increased risk of all-cause mortality (HR 2.21; 95% CI 1.35-3.63; p = 0.002). In the sensitivity analyses, KPC-Kp colonization was not associated with mortality in any of the analyzed subcohorts, including patients who did not develop KPC-Kp infection (HR 0.93; 95%CI: 0.60-1.43; p=0.74).

CONCLUSIONS

KPC-Kp rectal colonization was not associated with crude mortality. Mortality increased when colonized patients developed severe KPC-Kp infection (ICS > 7). Rectal colonization was a necessary although insufficient condition to die from a KPC-Kp infection.

Treatment of UTIs Due to Klebsiella pneumoniae Carbapenemase-Producers: How to Use New Antibiotic Drugs? A Narrative Review

Background: K. pneumoniae is one of the bacteria most frequently causing health care-associated urinary tract infections, and increasingly incriminating Klebsiella pneumoniae carbapenemase producers (KPCp). Most infections caused by KPCp are nosocomial and might cause serious issues, even leading to death in half of the reported cases. Our aim was to identify the best strategy, based on available scientific data, for the use of new antibiotic treatments to manage KPCp UTIs. Methods: this narrative review of the literature was performed according to the criteria of preferred reporting items for systematic review and meta-analyses statement (PRISMA) (2020). Results and Conclusions: KPCp-UTIs are a real challenge for physicians. While cefiderocol, meropenem-vaborbactam, ceftazidim-avibactam, and imipenem-relebactam represent a major step forward in the treatment of these UTIs, no guidelines are currently available, in view of choosing the most appropriate treatment, in each specific case.

Molecular Analysis and Antimicrobial Resistance Pattern of Tigecycline-Non-Susceptible K. pneumoniae Isolated from a Tertiary Care Hospital of East Asia

Introduction

Tigecycline is one of the last resorts for carbapenem-resistant K. pneumoniae (CRKP) infections. Indeed, tigecycline-non-susceptible K. pneumoniae (TNSKP) strains are increasingly treated with the use of tigecycline. In this study, we attempted to better understand their epidemiological trends and characteristics. K. pneumoniae were collected from 2017 to 2020 at the First Affiliated Hospital of Nanchang University.

Methods

Thirty-four TNSKP strains were selected during the study period, all of which were analyzed using antimicrobial susceptibility testing, multilocus sequence typing (MLST), and pulsed-field gel electrophoresis (PFGE). PCR and DNA sequencing were performed for the detection of β-lactamase genes and carbapenemase genes, and the mutation analysis of tet(A), tet(X), tet(L), tet(M), rpsJ, ramR, and oqxR, which are related to tigecycline resistance. Virulence gene and capsular genotype testing were conducted to identify whether the TNSKP strains were hypervirulent Klebsiella pneumoniae.

Results

An epidemiology analysis showed that Klebsiella pneumoniae carbapenemase-2 (KPC-2) was the predominant carbapenemase in tigecycline non-susceptible carbapenem-resistant K. pneumoniae (TNSCRKP) (96.7%), and the dominant clone type was ST11-K14K64 (82.4%). Among them, 55.9% (19/34) of strains were from each department of ICU, particularly EICU and neurosurgery ICU. In order to further understand the molecular mechanisms of the TNSKP, a polymerase chain reaction of the resistant determinants was carried out. The results detected many tigecycline-resistant genes, such as tet(A) (97.1%), tet(X) (17.6%), rpsJ (97.1%), and ramR (8.8%).

Conclusion

As the results of this study reveal, we should take effective measures to control the increase in TNSKP.

The Metabolome of Carbapenem-Resistant Klebsiella pneumoniae Infection in Plasma

AIM

Carbapenem-resistant Klebsiella pneumoniae- (CR-Kp-) mediated infections represent a challenge for clinical practitioners due to their expanding prevalence in hospital environments and antibiotic resistance. However, few studies have shown metabolic changes of carbapenem-resistant Klebsiella pneumoniae and CR-Kp-negative patients, and relevant studies are urgently needed.

METHODS

In this study, we comprehensively profile the metabolites of 20 CR-Kp-positive and 18 CR-Kp-negative patients in plasma by using 2D gas chromatography-time-of-flight mass spectrometry (GC×GC-TOFMS).

RESULTS

We identified 58 metabolites that were carbapenem-resistant Klebsiella pneumoniae-associated. N-Acetyl glucosamine, butanedioic acid, and myoinositol play a significant character in CR-Kp infection.

CONCLUSIONS

Our study provides valuable data to serve as potential targets for developing therapies against CR-Kp infection.

Resistance in Enterobacterales is higher among people with HIV

BACKGROUND

Multidrug-resistant Enterobacterales (MDR-E) are important pathogens. People with human immunodeficiency virus (HIV) may be at greater risk for MDR-E infection given relatively high antibiotic exposure and burden of comorbidities.

METHODS

Analyses were conducted using data collected on 36,521 patients in a healthcare system in North Carolina, who had at least 1 clinical culture with growth of an Enterobacterales species from 2000-2018; 440 were people with HIV infection (PWH). We used generalized linear models to estimate prevalence ratios and differences contrasting patients with and without HIV for resistance to individual antibiotic classes, as well as MDR-E. We assessed trends in prevalence over time by calculating the 5-year moving average and fitting restricted cubic spline models.

RESULTS

The overall prevalence of MDR-E was higher among PWH (21.5% [95% CI: 18.2%-25.1%]) versus patients without HIV (16.5% [95% CI: 16.2%-16.9%], with an adjusted prevalence ratio of 1.38 (95% CI: 1.14-1.65). PWH had higher rates of antimicrobial resistance than patients without HIV for all antibiotic classes analyzed, including penicillins, penicillin/beta-lactamase inhibitor combinations, and sulfonamides. MDR-E prevalence was 3 to 10 percentage points higher among PWH than patients without HIV throughout the study period based on the 5-year moving average.

CONCLUSION

In a large clinical study population in the southeastern US from 2000-2018, the prevalence of antibacterial resistance among Enterobacterales was consistently higher among PWH than patients without HIV. These data highlight the importance of identifying and mitigating the factors contributing to antimicrobial resistance in PWH, given the potential clinical consequences of these resistant pathogens.

Predicting mortality in intensive care unit patients infected with Klebsiella pneumoniae: A retrospective cohort study

INTRODUCTION

Although several models to predict intensive care unit (ICU) mortality are available, their performance decreases in certain subpopulations because specific factors are not included. Moreover, these models often involve complex techniques and are not applicable in low-resource settings. We developed a prediction model and simplified risk score to predict 14-day mortality in ICU patients infected with Klebsiella pneumoniae.

METHODOLOGY

A retrospective cohort study was conducted using data of ICU patients infected with Klebsiella pneumoniae at the largest tertiary hospital in Northern Vietnam during 2016-2018. Logistic regression was used to develop our prediction model. Model performance was assessed by calibration (area under the receiver operating characteristic curve-AUC) and discrimination (Hosmer-Lemeshow goodness-of-fit test). A simplified risk score was also constructed.

RESULTS

Two hundred forty-nine patients were included, with an overall 14-day mortality of 28.9%. The final prediction model comprised six predictors: age, referral route, SOFA score, central venous catheter, intracerebral haemorrhage surgery and absence of adjunctive therapy. The model showed high predictive accuracy (AUC = 0.83; p-value Hosmer-Lemeshow test = 0.92). The risk score has a range of 0-12 corresponding to mortality risk 0-100%, which produced similar predictive performance as the original model.

CONCLUSIONS

The developed prediction model and risk score provide an objective quantitative estimation of individual 14-day mortality in ICU patients infected with Klebsiella pneumoniae. The tool is highly applicable in practice to help facilitate patient stratification and management, evaluation of further interventions and allocation of resources and care, especially in low-resource settings where electronic systems to support complex models are missing.

Co-occurrence of Carbapenemase-encoding Genes Among Klebsiella pneumoniae Clinical Isolates: Positive Relationship of bla NDM and bla SIM with Imipenem Resistance

Background: Carbapenem-resistant Klebsiella pneumoniae (CR-KP), known as a significant public health threat, is the most common causative agent of nosocomial and community-acquired infections. Objectives: This study aimed to evaluate resistance to carbapenems and determine the prevalence of carbapenemase genes and multilocus sequence typing (MLST) of K. pneumoniae clinical isolates. Methods: One-hundred K. pneumoniae isolates were evaluated. The minimum inhibitory concentrations (MIC) of imipenem and meropenem were assessed by the broth microdilution method. Multiplex-polymerase chain reaction (PCR) was applied to detect 11 carbapenemase-encoding genes belonging to different classes. The alleles and sequence types (ST) of three isolates were identified by MLST. Results: The MIC of carbapenems for the isolates ranged from 0.062 to 32 µg/mL. Overall, resistance rates to imipenem and meropenem were reported 11% and 34%, respectively. The bla IMP gene was the most abundant (78.4%), followed by bla OXA-48 (48.6%), bla GIM (27%), bla KPC (27%), bla SIM (21.6%), bla BIC (21.6%), bla NDM (16.2%), bla AIM (16.2%), bla VIM (16.2%), bla DIM (8.1%), and bla SPM (8.1%). The co-existence of carbapenemase genes was observed in 81.8% of the isolates. A positive relationship was found between the presence of bla NDM and bla SIM and resistance to imipenem. Multilocus sequence typing results showed three different sequence types, including ST14, ST5188, and ST1861. Conclusions: This study revealed a high prevalence of CR-KP isolates that suggests a high risk of horizontal gene transfer and potential to spread resistance among other strains. Since STs are reported for the first time in Iran, they can be considered as emerging strains.

Effect on 30-day mortality and duration of hospitalization of empirical antibiotic therapy in CRGNB-infected pneumonia

BACKGROUND

The objective of this study was to investigate whether unreasonable empirical antibiotic treatment (UEAT) had an impact on 30-day mortality and duration of hospitalization in bacterial pneumonia caused by carbapenem-resistant gram-negative bacteria (CRGNB).

METHODS

This was a retrospective cohort study involving CRGNB-infected pneumonia. All CRGNB-infected pneumonia patients received empirical and targeted antibiotic treatment (TAT), and they were divided into reasonable empirical antibiotic treatment (REAT) and UEAT according to whether the empirical antibiotic treatment (EAT) was reasonable. The data of the two groups were compared to analyze their influence on the 30-day mortality and hospitalization time in CRGNB-infected pneumonia patients. Moreover, we also considered other variables that might be relevant and conducted multivariable regression analysis of 30-day mortality and duration of hospitalization in CRGNB-infected pneumonia patients.

RESULTS

The study collected 310 CRGNB-infected pneumonia patients, the most common bacterium is Acinetobacter baumannii (211/310 [68%]), the rest were Klebsiella pneumoniae (46/310 [15%]), Pseudomonas aeruginosa and others (53/310 [17%]). Among them, 76/310 (24.5%) patients received REAT. In the analysis of risk factors, dementia, consciousness were risk factors of 30-day mortality, pulmonary disease, hemodynamic support at culture taken day and recent surgery were risk factors for longer hospital stay. The analysis of 30-day mortality showed that UEAT was not associated with 30-day mortality for the 30-day mortality of REAT and UEAT were 9 of 76 (11.84%) and 36 of 234 (15.38%) (P = 0.447), respectively. Meanwhile, there was difference between REAT and UEAT (P = 0.023) in the analysis of EAT on hospitalization time in CRGNB-infected pneumonia patients.

CONCLUSIONS

UEAT was not associated with 30-day mortality while was related to duration of hospitalization in CRGNB-infected pneumonia patients, in which Acinetobacter baumanniii accouned for the majority.

Broadly reactive human CD4+ T cells against Enterobacteriaceae are found in the naïve repertoire and are clonally expanded in the memory repertoire

Enterobacteriaceae are a large family of Gram-negative bacteria that includes both commensals and opportunistic pathogens. The latter can cause severe nosocomial infections, with outbreaks of multi-antibiotics resistant strains, thus being a major public health threat. In this study, we report that Enterobacteriaceae-reactive memory Th cells were highly enriched in a CCR6+ CXCR3+ Th1*/17 cell subset and produced IFN-γ, IL-17A, and IL-22. This T cell subset was severely reduced in septic patients with K. pneumoniae bloodstream infection who also selectively lacked circulating K. pneumonie-reactive T cells. By combining heterologous antigenic stimulation, single cell cloning and TCR Vβ sequencing, we demonstrate that a large fraction of memory Th cell clones was broadly cross-reactive to several Enterobacteriaceae species. These cross-reactive Th cell clones were expanded in vivo and a large fraction of them recognized the conserved outer membrane protein A antigen. Interestingly, Enterobacteriaceae broadly cross-reactive T cells were also prominent among in vitro primed naïve T cells. Collectively, these data point to the existence of immunodominant T cell epitopes shared among different Enterobacteriaceae species and targeted by cross-reactive T cells that are readily found in the pre-immune repertoire and are clonally expanded in the memory repertoire.

Silver Nanoparticles Induce a Triclosan-Like Antibacterial Action Mechanism in Multi-Drug Resistant Klebsiella pneumoniae

Infections associated with antimicrobial-resistant bacteria now represent a significant threat to human health using conventional therapy, necessitating the development of alternate and more effective antibacterial compounds. Silver nanoparticles (Ag NPs) have been proposed as potential antimicrobial agents to combat infections. A complete understanding of their antimicrobial activity is required before these molecules can be used in therapy. Lysozyme coated Ag NPs were synthesized and characterized by TEM-EDS, XRD, UV-vis, FTIR spectroscopy, zeta potential, and oxidative potential assay. Biochemical assays and deep level transcriptional analysis using RNA sequencing were used to decipher how Ag NPs exert their antibacterial action against multi-drug resistant Klebsiella pneumoniae MGH78578. RNAseq data revealed that Ag NPs induced a triclosan-like bactericidal mechanism responsible for the inhibition of the type II fatty acid biosynthesis. Additionally, released Ag+ generated oxidative stress both extra- and intracellularly in K. pneumoniae. The data showed that triclosan-like activity and oxidative stress cumulatively underpinned the antibacterial activity of Ag NPs. This result was confirmed by the analysis of the bactericidal effect of Ag NPs against the isogenic K. pneumoniae MGH78578 ΔsoxS mutant, which exhibits a compromised oxidative stress response compared to the wild type. Silver nanoparticles induce a triclosan-like antibacterial action mechanism in multi-drug resistant K. pneumoniae. This study extends our understanding of anti-Klebsiella mechanisms associated with exposure to Ag NPs. This allowed us to model how bacteria might develop resistance against silver nanoparticles, should the latter be used in therapy.

In vitro activity of tigecycline against multidrug-resistant Enterobacteriaceae isolates from skin and soft tissue infections

Background

Tigecycline, a new agent against multidrug-resistant (MDR) bacteria, is especially licensed for use in complicated skin and soft tissue and intra-abdominal infections. We aimed to study the recent in vitro activity of tigecycline against MDR Enterobacteriaceae skin and soft tissue isolates.

Methods

Consecutive isolates (56 Escherichia coli, 48 Klebsiella pneumoniae) were subjected to tigecycline susceptibility testing by Ezy MIC test and interpreted as per European Committee on Antimicrobial Susceptibility Testing.

Results

The minimum inhibitory concentrations (MICs) of tigecycline ranged from 0.016 to 48 μg/mL, with MIC₅₀ 0.19 μg/mL and MIC₉₀ 1.0 μg/mL respectively. Seven (6.7%) isolates were resistant to tigecycline, all K. pneumoniae.

Conclusion

Tigecycline remains a viable therapeutic option against MDR isolates, with excellent in vitro activity against E. coli and promising activity against K. pneumoniae. However, the limited availability of alternate therapeutic armamentarium necessitates its use with extreme judiciousness along with continuous monitoring for the emergence and spread of resistance.

•

Tigecycline has excellent in vitro activity against MDR E. coli.

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Tigecycline has comparatively lower activity against MDR K. pneumoniae.

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Tigecycline remains a viable therapeutic option against MDR E. coli isolates.

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Limited availability of alternate therapy necessitates cautious use of tigecycline.

Detection of carbapenem-resistant Klebsiella pneumoniae strains harboring carbapenemase, beta-lactamase and quinolone resistance genes in intensive care unit patients

Aim: Carbapenem-resistant Klebsiella pneumoniae (CR-Kp) strains are important nosocomial pathogens worldwide. In this study, we aimed to reveal the antibiotic resistance of clinical CR-Kp strains and determine the presence of KPC, OXA-48, VIM and IMP carbapenemase genes. CTX-M-1, TEM-1, SHV-1 extended-spectrum beta-lactamase (ESBL) genes, qnrA, qnrB, qnrS plasmid-mediated quinolone resistance genes and sul1 and sul2 sulfonamide resistance genes provided molecular epidemiological data.

Methods: A total of 175 K. pneumoniae strains were isolated from clinical samples of patients hospitalised in an intensive care unit (ICU) betweent April and October 2017. The strains were identified with conventional methods, with VITEK 2 (BioMerieux, France) and MALDI-TOF MS (Bruker, USA). Antimicrobial susceptibilities were tested using the disc-diffusion method and E-test (BioMerieux, France). Antimicrobial resistance genes were investigated via real-time PCR in strains identified as CR-Kp.

Results: High frequencies of bla_TEM-1 (86.36%), bla_SHV-1 (86.36%), and bla_CTX-M-1 (95.45%) genes were found in CR-Kp strains. Morever, all three ESBL genes coexisted in 77.3% of all strains. bla_KPC was detected in 12 (54.55%) of the strains, and 4 of them which had an MIC> 16 μg/mL to imipenem showed bla_OXA-48 positivity as well. The qnrS gene determinant (86.36%) had the highest frequency, and strains carrying qnrA showed higher MICs for ciprofloxacin.

Conclusion: CR-Kp strains are able to develop different antimicrobial resistance patterns according to regional changes in antimicrobial therapeutic policies. Thus, it is important to monitor the regional molecular epidemiological data for efficient treatment.

Sepsis-A Retrospective Cohort Study of Bloodstream Infections

Bloodstream infections (BSIs) are among the leading causes of morbidity and mortality worldwide, among infectious diseases. Local knowledge of the main bacteria involved in BSIs and their associated antibiotic susceptibility patterns is essential to rationalize the empiric antimicrobial therapy. The aim of this study was to define the incidence of infection and evaluate the antimicrobial resistance profile of the main pathogens involved in BSIs. This study enrolled patients of all ages and both sexes admitted to the University Hospital “San Giovanni di Dio e Ruggi d’Aragona”, Salerno, Italy between January 2015 to December 2019. Bacterial identification and antibiotic susceptibility testing were performed with Vitek 2. A number of 3.949 positive blood cultures were included out of 24,694 total blood cultures from 2015 to 2019. Coagulase-negative staphylococci (CoNS) were identified as the main bacteria that caused BSI (17.4%), followed by Staphylococcus aureus (12.3%), Escherichia coli (10.9%), and Klebsiella pneumoniae (9.4%). Gram-positive bacteria were highly resistant to Penicillin G and Oxacillin, while Gram-negative strains to Ciprofloxacin, Cefotaxime, Ceftazidime, and Amoxicillin-clavulanate. High susceptibility to Vancomycin, Linezolid, and Daptomycin was observed among Gram-positive strains. Fosfomycin showed the best performance to treatment Gram-negative BSIs. Our study found an increase in resistance to the latest generation of antibiotics over the years. This suggests an urgent need to improve antimicrobial management programs to optimize empirical therapy in BSI.

Performance of Population Pharmacokinetic Models in Predicting Polymyxin B Exposures

Polymyxin B is the last line of defense in treating multidrug-resistant gram-negative bacterial infections. Dosing of polymyxin B is currently based on total body weight, and a substantial intersubject variability has been reported. We evaluated the performance of different population pharmacokinetic models to predict polymyxin B exposures observed in individual patients. In a prospective observational study, standard dosing (mean 2.5 mg/kg daily) was administered in 13 adult patients. Serial blood samples were obtained at steady state, and plasma polymyxin B concentrations were determined by a validated liquid chromatography tandem mass spectrometry (LC-MS/MS) method. The best-fit estimates of clearance and daily doses were used to derive the observed area under the curve (AUC) in concentration–time profiles. For comparison, 5 different population pharmacokinetic models of polymyxin B were conditioned using patient-specific dosing and demographic (if applicable) variables to predict polymyxin B AUC of the same patient. The predictive performance of the models was assessed by the coefficient of correlation, bias, and precision. The correlations between observed and predicted AUC in all 5 models examined were poor (r² < 0.2). Nonetheless, the models were reasonable in capturing AUC variability in the patient population. Therapeutic drug monitoring currently remains the only viable approach to individualized dosing.

Multidrug-Resistant Bacteria in the Community: An Update

Multidrug-resistant bacteria are among the most important current threats to public health. Typically, they are associated with nosocomial infections. However, some have become prevalent causes of community-acquired infections, such as Neisseria gonorrhoeae, Shigella, Salmonella, and Streptococcus pneumoniae. The community spread of multidrug-resistant bacteria is also a crucial development. An important global threat on the horizon is represented by production of carbapenemases by community-acquired hypervirulent Klebsiella pneumoniae. Such strains have already been found in Asia, Europe, and North America. Prevention of further community spread of multidrug-resistant bacteria is of the utmost importance, and will require a multidisciplinary approach involving all stakeholders.

Rising Klebsiella pneumoniae Infections and Its Expanding Drug Resistance in the Intensive Care Unit of a Tertiary Healthcare Hospital, Saudi Arabia

Nosocomial infections caused by Klebsiella pneumoniae and other Gram-negative organisms have emerged as a significant health problem especially in intensive care units (ICU). This study aims to examine K. pneumoniae infections in the ICU of Aseer Central Hospital and to determine their antimicrobial susceptibility and their relationship to patients' clinical outcomes. This is a retrospective observational study done in a tertiary care center in the Aseer region in Saudi Arabia. The study spanned from January 2018 to December 2019. Demographic, microbiologic, and patient outcomes were collected from 276 patients with various infections. Identification of isolates and in vitro susceptibility to 32 antimicrobial agents were done by the Vitek 2 automated system (bioMérieux, Marcy-l'Étoile, France). Prevalence of K. pneumoniae bacteria, their susceptibility to antimicrobials, and effect on clinical outcome were studied. Two hundred seventy-six K. pneumoniae were recovered from ICU patients with various infections. K. pneumoniae isolates (n=276) were collected mainly from the respiratory tract (61%) and K. pneumoniae represented 39% of the major causal agents of ICU infections, followed by Acinetobacter spp. (30%), Pseudomonas aeruginosa (10.0%), Escherichia coli (7%), and others (14%). The mortality among the 276 ICU patients was 33.3%; K. pneumoniae was connected to 42% of the cases and 67% of the total deaths were between 50 and 90 years of age. K. pneumoniae demonstrated high sensitivity and hence can be recommended for in vivo treatment for tigecycline (81%), cefazolin (77.2%), colistin (64.9%), and to a lesser extent norfloxacin (60%) and imipenem (55.5%). High resistance was detected for ampicillin (100%), extended-spectrum β-lactamases-sulbactam (ESBL-SCM) (100%), piperacillin (100%), and ceftazidime (92.5%). Resistance to carbapenems was elevated in ertapenem (65.2%) and meropenem (61.7%). The increase of K. pneumoniae represents a threat to ICU patients, although K. pneumoniae infections were results rather than the causes, as it was connected to almost half of the ICU mortalities. Tigecycline alone or in combination with colistin on high-dose regimens could be a more effective therapy for treating carbapenem-resistant K. pneumoniae infections.

High Prevalence of 16S rRNA Methyltransferase Genes in Carbapenem-Resistant Klebsiella pneumoniae Clinical Isolates Associated with Bloodstream Infections in 11 Chinese Teaching Hospitals

Objective

The 16S rRNA methylase-mediated high-level resistance to aminoglycosides has become a great concern. The purpose of the study was to investigate the occurrence of 16S rRNA methyltransferase (RMTase) genes in carbapenem-resistant Klebsiella pneumoniae (CRKP) clinical isolates associated with bloodstream infections (BSIs) in China.

Methods

From July 2015 to December 2018, a total of 137 unique CRKP clinical isolates associated with BSIs were collected from 11 Chinese teaching hospitals. PCR and DNA sequencing were used to identify 16S RMTase genes. Whole-genome sequencing (WGS) was performed on all CRKP clinical isolates. Relevant information was extracted from WGS data (antibiotic resistance determinants, K-type and wzi allelic types). All 16S RMTase-producing CRKP clinical isolates were characterized by antimicrobial susceptibility testing, multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE).

Results

In this study, 137 CRKPs were found to harbor at least one carbapenemase gene. Among 137 CRKPs, 78 (56.9%, 78/137) were positive for 16S RMTase genes (5 for armA, 70 for rmtB, 3 for both armA and rmtB) and highly resistant to gentamicin and amikacin (MICs ≥256 mg/L). Seventy-five isolates harboring 16S RMTase genes also produced ESBLs. In this study, 5 sequence types (STs) and 6 capsule serotypes were found among 78 isolates positive for 16S RMTases genes, while 14 STs and 6 capsule serotypes were found among 59 isolates negative for 16S RMTases genes. Compared with the isolates negative for 16S RMTases genes, the STs and capsular serotypes of 16S RMTases-positive strains are more concentrated. Among 78 16S RMTases-positive strains, the most prevalent clone type is ST11-PFGE-B-KL64-wzi64 (62.8%, 49/78), which mainly carries the rmtB and bla_KPC genes and is distributed in 7 provinces in China.

Conclusion

A high prevalence of 16S RMTase genes was found among CRKP clinical isolates associated with BSIs from Chinese teaching hospitals, which was attributed to the dissemination of the ST11-PFGE-B-KL64-wzi64 clone.

Population structure across scales facilitates coexistence and spatial heterogeneity of antibiotic-resistant infections

Antibiotic-resistant infections are a growing threat to human health, but basic features of the eco-evolutionary dynamics remain unexplained. Most prominently, there is no clear mechanism for the long-term coexistence of both drug-sensitive and resistant strains at intermediate levels, a ubiquitous pattern seen in surveillance data. Here we show that accounting for structured or spatially-heterogeneous host populations and variability in antibiotic consumption can lead to persistent coexistence over a wide range of treatment coverages, drug efficacies, costs of resistance, and mixing patterns. Moreover, this mechanism can explain other puzzling spatiotemporal features of drug-resistance epidemiology that have received less attention, such as large differences in the prevalence of resistance between geographical regions with similar antibiotic consumption or that neighbor one another. We find that the same amount of antibiotic use can lead to very different levels of resistance depending on how treatment is distributed in a transmission network. We also identify parameter regimes in which population structure alone cannot support coexistence, suggesting the need for other mechanisms to explain the epidemiology of antibiotic resistance. Our analysis identifies key features of host population structure that can be used to assess resistance risk and highlights the need to include spatial or demographic heterogeneity in models to guide resistance management.

Antimicrobial and antibiofilm activities of ursolic acid against carbapenem-resistant Klebsiella pneumoniae

Previous studies demonstrated that ursolic acid (UA) present in apple pomace displays antimicrobial activity against some microorganisms, but the underlying mechanisms associated with this activity remain unexplored. Furthermore, there are no reports on the effect of UA on carbapenem-resistant Klebsiella pneumoniae (CRKP). This study examined the antimicrobial activity and mode of action of UA against CRKP was examined. Minimum inhibitory concentration (MIC) of UA against CRKP was determined by the agar dilution method. Variations in the intracellular pH (pHin), ATP concentration, and cell membrane potential were measured to assess the influence of UA on the cell membrane. Our results show that UA was effective against CRKP at an MIC of 0.8 mg ml-1. UA disrupted the cell membrane integrity of CRKP, exhibited strong inhibitory effects against biofilm formation and biofilm-related gene expression, and inactivated CRKP cells encased in biofilms. Thus, UA shows promise for use in combination with other antibiotics to treat multidrug resistant K. pneumoniae infections.

Rapid Detection of Mobilized Colistin Resistance using a Nucleic Acid Based Lab-on-a-Chip Diagnostic System

The increasing prevalence of antimicrobial resistance is a serious threat to global public health. One of the most concerning trends is the rapid spread of Carbapenemase-Producing Organisms (CPO), where colistin has become the last-resort antibiotic treatment. The emergence of colistin resistance, including the spread of mobilized colistin resistance (mcr) genes, raises the possibility of untreatable bacterial infections and motivates the development of improved diagnostics for the detection of colistin-resistant organisms. This work demonstrates a rapid response for detecting the most recently reported mcr gene, mcr−9, using a portable and affordable lab-on-a-chip (LoC) platform, offering a promising alternative to conventional laboratory-based instruments such as real-time PCR (qPCR). The platform combines semiconductor technology, for non-optical real-time DNA sensing, with a smartphone application for data acquisition, visualization and cloud connectivity. This technology is enabled by using loop-mediated isothermal amplification (LAMP) as the chemistry for targeted DNA detection, by virtue of its high sensitivity, specificity, yield, and manageable temperature requirements. Here, we have developed the first LAMP assay for mcr−9 - showing high sensitivity (down to 100 genomic copies/reaction) and high specificity (no cross-reactivity with other mcr variants). This assay is demonstrated through supporting a hospital investigation where we analyzed nucleic acids extracted from 128 carbapenemase-producing bacteria isolated from clinical and screening samples and found that 41 carried mcr−9 (validated using whole genome sequencing). Average positive detection times were 6.58 ± 0.42 min when performing the experiments on a conventional qPCR instrument (n = 41). For validating the translation of the LAMP assay onto a LoC platform, a subset of the samples were tested (n = 20), showing average detection times of 6.83 ± 0.92 min for positive isolates (n = 14). All experiments detected mcr−9 in under 10 min, and both platforms showed no statistically significant difference (p-value > 0.05). When sample preparation and throughput capabilities are integrated within this LoC platform, the adoption of this technology for the rapid detection and surveillance of antimicrobial resistance genes will decrease the turnaround time for DNA detection and resistotyping, improving diagnostic capabilities, patient outcomes, and the management of infectious diseases.

The First Egyptian Report Showing the Co-Existence of bla NDM-25, bla OXA-23, bla OXA-181, and bla GES-1 Among Carbapenem-Resistant K. pneumoniae Clinical Isolates Genotyped by BOX-PCR

Background and Objective

The emergence of carbapenem-resistant K. pneumoniae (CRKP) continues to escalate and is alarming because of the emergence of pan drug-resistant strains. The objective of this study was to investigate the existence of 12 carbapenemase genes among CRKP clinical isolates.

Methods

Ninety-six Klebsiella spp. clinical isolates were collected. The isolates were identified phenotypically and genotypically. These isolates were screened for susceptibility to 24 different antibiotics. The modified Hodge test (MHT) and the Carba Nordmann/Poirel (NP) test were used to phenotypically screen carbapenem-resistant strains for carbapenemase production. Phenotypic characterization of carbapenemases was performed using the combined disk synergy test (CDST). Additionally, the presence of 12 carbapenemase genes in CRKP isolates was investigated. The DNA sequence of bla _NDM and bla _GES genes was determined. The BOX-PCR technique was used to determine the clonal relationship between CRKP isolates.

Results

All carbapenem-resistant isolates were related to K. pneumoniae. Susceptibility testing showed that 19.79% (19/96) of the collected isolates were carbapenem-resistant. Of the CRKP isolates, 68.42% (13/19) tested positive for the MHT and Carba NP test. CDST showed that 42.11% (8/19), 63.16% (12/19), 47.37% (9/19), and 73.68% (14/19) of the CRKP isolates tested positive for the inhibitory effect of clavulanic acid, sulbactam, phenylboronic acid, and tazobactam, respectively, while 84.21% (16/19) and 68.42% (13/16) tested positive for the inhibitory effect of EDTA and mercaptopropionic acid, respectively. It was found that 10.53% (2/19) of the isolates tested positive for the inhibitory effect of sodium chloride. Molecular investigation of carbapenemases showed that 26.32% (5/19), 73.68% (14/19), 21.05% (4/19), 10.53% (2/19), and 5.26% (1/19) of the isolates tested positive for bla _NDM, bla _OXA-48, bla _OXA-181, bla _OXA-51, and bla _OXA-23, respectively. None of the isolates tested positive for bla _OXA-40 and bla _OXA-58. Two allelic variants of bla _NDM (bla _NDM-1 and bla _NDM-25) were detected. BOX-PCR revealed high clonal relatedness between CRKP isolates.

Conclusion

MHT was more sensitive than Carba NP test for evaluating carbapenemase production and class D carbapenemase genes were the most prevalent of the 12 carbapenemase genes that were evaluated.

Mortality, clinical and microbiological response following antibiotic therapy among patients with carbapenem-resistant Klebsiella pneumoniae infections (a meta-analysis dataset)

This meta-analysis was conducted to assess mortality, clinical and microbiological response following antibiotic therapy among patients with carbapenem-resistant Klebsiella pneumoniae (CRKP) infections. Fifty-four observational studies involving 3195 CRKP-infected patients who received antibiotic treatment were included. We found combination therapy to be associated with lower mortality than monotherapy, but no differences in clinical and microbiological response. Among the various combination therapies, no significant differences in mortality, clinical and microbiological response were found. Moreover, clinical outcomes did not differ significantly among various monotherapies. This report describes the data related to the article entitled: "A systematic review and meta-analysis of treatment outcomes following antibiotic therapy among patients with carbapenem-resistant Klebsiella pneumoniae infections".

CRISPR-Cas influences the acquisition of antibiotic resistance in Klebsiella pneumoniae

In the US Carbapenem resistance in Klebsiella pneumoniae (Kp) is primarily attributed to the presence of the genes bla_KPC-2 and bla_KPC-3, which are transmitted via plasmids. Carbapenem-resistant Kp (CR-Kp) infections are associated with hospital outbreaks. They are difficult to treat, and associated with high mortality rates prompting studies of how resistance is obtained. In this study, we determined the presence of CRISPR-Cas in 304 clinical Kp strains. The CRISPR-Cas system has been found to prevent the spread of plasmids and bacteriophages, and therefore limits the horizontal gene transfer mediated by these mobile genetic elements. Here, we hypothesized that only those Kp strains that lack CRISPR-Cas can acquire CR plasmids, while those strains that have CRISPR-Cas are protected from gaining these plasmids and thus maintain sensitivity to antimicrobials. Our results show that CRISPR-Cas is absent in most clinical Kp strains including the clinically important ST258 clone. ST258 strains that continue to be sensitive to carbapenems also lack CRISPR-Cas. Interestingly, CRISPR-Cas positive strains, all non-ST258, exhibit lower resistance rates to antimicrobials than CRISPR-Cas negative strains. Importantly, we demonstrate that the presence of CRISPR-Cas appears to inhibit the acquisition of bla_KPC plasmids in 7 Kp strains. Furthermore, we show that strains that are unable to acquire bla_KPC plasmids contain CRISPR spacer sequences highly identical to those found in previously published multidrug-resistance-containing plasmids. Lastly, to our knowledge this is the first paper demonstrating that resistance to bla_KPC plasmid invasion in a CRISPR-containing Kp strain can be reversed by deleting the CRISPR-cas cassette.

Advances in the therapy of bacterial bloodstream infections

BACKGROUND

Advances in the diagnostic and therapeutic management of patients with bloodstream infections (BSIs) have been achieved in the last years, improving clinical outcome. However, mortality associated with some pathogens, such as Staphylococcus aureus and Enterococcus spp., is still high. In addition, the spread of antibiotic resistance, mainly among Gram-negative bacteria, reduces treatment options in some circumstances. Therefore, interest in new drugs, combination regimens and optimal dosing schedules is rising.

OBJECTIVES

Our aim is to summarize the current evidence on available antibiotic regimens for patients with bacterial BSI, focusing on drug choice, combination regimens and optimal dosing schedules. We selected bacteria that are difficult to manage because of virulence factors (i.e. methicillin-susceptible S. aureus), tolerance to antibiotic activity (i.e. Enterococcus faecalis), and/or susceptibility patterns (i.e. methicillin-resistant S. aureus, vancomycin-resistant enterococci, carbapenem-resistant Enterobacteriaceae, multidrug-resistant Pseudomonas aeruginosa and carbapenem-resistant Acinetobacter baumannii).

SOURCES

MEDLINE search with English language and publication in the last 5 years as limits.

CONTENT AND IMPLICATIONS

The literature gaps on the use of new drugs, the uncertainties regarding the use of combination regimens, and the need to optimize dosing schedules in some circumstances (e.g. augmented renal clearance, renal replacement therapy, high inoculum BSI sources, and isolation of bacteria showing high MICs) have been revised.

External validation of the INCREMENT-CPE mortality score in a carbapenem-resistant Klebsiella pneumoniae bacteraemia cohort: the prognostic significance of colistin resistance

External validation of the INCREMENT-CPE risk score (ICS) for 30-day all-cause mortality is needed. There is also scarce information about whether colistin resistance influences the prognosis of carbapenem-resistant Klebsiella pneumoniae (CRKp) bacteraemia. In this study, the ability of ICS to predict all-cause mortality in the KAPECOR cohort was calculated using the area under the receiver operating characteristic (AUROC) curve. The association of colistin resistance with mortality was studied. The ICS showed an AUROC curve of 0.77 (95% CI 0.68-0.86). A cut-off of 8 points showed 96.8% sensitivity and 50.7% specificity. Mortality of low-risk patients was not different in those treated with monotherapy versus combination therapy. However, mortality of high-risk patients treated with combination therapy (37.8%) was significantly lower than in those treated with monotherapy (68.4%) (P = 0.008). To study the prognostic significance of colistin resistance, 83 selected cases of bacteraemia due to colistin-susceptible CRKp were obtained from the INCREMENT cohort for comparison. Colistin resistance could not be shown to be associated with higher mortality in either the high-risk ICS group [adjusted odds ratio (aOR) = 1.56, 95% CI 0.69-3.33; P = 0.29] or in 37 ICS-matched pairs (aOR = 1.38, 95% CI 0.55-3.42; P = 0.49), or in a sensitivity analysis including only KPC isolates (aOR = 1.81, 95% CI 0.73-4.57; P = 0.20), but the precision of estimates was low. These results validate ICS for all-cause mortality and to optimise targeted therapy for CRKp bacteraemia. Colistin resistance was not clearly associated with increased mortality.

Nacubactam Enhances Meropenem Activity against Carbapenem-Resistant Klebsiella pneumoniae Producing KPC

Carbapenem-resistant Enterobacteriaceae (CRE) are resistant to most antibiotics, making CRE infections extremely difficult to treat with available agents. Klebsiella pneumoniae carbapenemases (KPC-2 and KPC-3) are predominant carbapenemases in CRE in the United States. Nacubactam is a bridged diazabicyclooctane (DBO) β-lactamase inhibitor that inactivates class A and C β-lactamases and exhibits intrinsic antibiotic and β-lactam "enhancer" activity against Enterobacteriaceae In this study, we examined a collection of meropenem-resistant K. pneumoniae isolates carrying bla _KPC-2 or bla _KPC-3; meropenem-nacubactam restored susceptibility. Upon testing isogenic Escherichia coli strains producing KPC-2 variants with single-residue substitutions at important Ambler class A positions (K73, S130, R164, E166, N170, D179, K234, E276, etc.), the K234R variant increased the meropenem-nacubactam MIC compared to that for the strain producing KPC-2, without increasing the meropenem MIC. Correspondingly, nacubactam inhibited KPC-2 (apparent K_i [K_{i  app}] = 31 ± 3 μM) more efficiently than the K234R variant (K_{i  app}  = 270 ± 27 μM) and displayed a faster acylation rate (k ₂ /K), which was 5,815 ± 582 M^-1 s^-1 for KPC-2 versus 247 ± 25 M^-1 s^-1 for the K234R variant. Unlike avibactam, timed mass spectrometry revealed an intact sulfate on nacubactam and a novel peak (+337 Da) with the K234R variant. Molecular modeling of the K234R variant showed significant catalytic residue (i.e., S70, K73, and S130) rearrangements that likely interfere with nacubactam binding and acylation. Nacubactam's aminoethoxy tail formed unproductive interactions with the K234R variant's active site. Molecular modeling and docking observations were consistent with the results of biochemical analyses. Overall, the meropenem-nacubactam combination is effective against carbapenem-resistant K. pneumoniae Moreover, our data suggest that β-lactamase inhibition by nacubactam proceeds through an alternative mechanism compared to that for avibactam.

Societal willingness to pay to avoid mortality and morbidity from Clostridioides difficile and carbapenem-resistant Enterobacteriaceae infections in the United States

BACKGROUND

Clostridioides difficile infection (CDI) is among the most common health care-associated infections in the United States and is increasingly affecting the elderly. Although carbapenem-resistant Enterobacteriaceae (CRE) infections are still relatively uncommon, there are reported increases in the rate of infection for certain strains, such as Klebsiella pneumoniae. This study examines the burden of mortality and morbidity for CDI and CRE infections in the United States and estimates the societal willingness to pay to avoid them.

METHODS

We use an analytic model to estimate the number of incident cases and associated health outcomes for CDI and CRE infections.

RESULTS

The number of CDI and CRE infection incident cases in the United States in 2016, is estimated at 468,567 and 9,620, respectively. These infections result in a total of 17,630 estimated deaths and 8,624 lost quality-adjusted life years among patients who survive per year.

CONCLUSIONS

Given the significant mortality and morbidity from these infections, the estimated societal willingness to pay to avoid them is high at $176.7 billion per year, of which 93.9% ($166.0 billion) is for CDI. Our estimates far exceed the medical care costs for CDIs and CRE infections reported in the literature despite not capturing the additional costs borne by third-party payers. As incident cases increase or resistant strains develop, the societal willingness to pay is also expected to increase.

Antimicrobial Resistance or Delayed Appropriate Therapy-Does One Influence Outcomes More Than the Other Among Patients With Serious Infections Due to Carbapenem-Resistant Versus Carbapenem-Susceptible Enterobacteriaceae?

Background

The relative contribution of antimicrobial resistance versus delayed appropriate treatment to the clinical and economic burden of Enterobacteriaceae infections is not well understood.

Methods

Using a large US hospital database, we identified all admissions between July 2011 and September 2014 with evidence of serious Enterobacteriaceae infection. The "index date" was the earliest date on which a culture positive for Enterobacteriaceae was drawn. Infections were classified as carbapenem-resistant (CRE) or carbapenem-susceptible (CSE). Receipt of antimicrobials with activity against all index pathogens on the index date or ≤2 days thereafter was deemed as "timely"; all other instances were "delayed." Associations between CRE status and delayed appropriate therapy on outcomes were estimated using inverse probability weighting and multivariate regression models (ie, logistic model for discharge destination and composite mortality [in-hospital death or discharge to hospice] or generalized linear model for duration of antibiotic therapy, hospital length of stay [LOS], and costs).

Results

A total of 50 069 patients met selection criteria; 514 patients (1.0%) had CRE. Overall, 67.5% of CSE patients (vs 44.6%, CRE) received timely appropriate therapy (P < .01). Irrespective of CRE status, patients who received delayed appropriate therapy had longer durations of antibiotic therapy and LOS, higher costs, lower likelihood of discharge to home, and greater likelihood of the composite mortality outcome (P for trend < .01).

Conclusions

Delayed appropriate therapy is a more important driver of outcomes than CRE, although the 2 factors are somewhat synergistic. Better methods of early CRE identification may improve outcomes in this patient population.

The antibiotic arms race: current and emerging therapy for Klebsiella pneumoniae carbapenemase (KPC) - producing bacteria

Introduction: The rapid spread of Klebsiella pneumoniae Carbapenemase (KPC)-producing bacteria comprises one of the greatest challenges to global health. Historically, clinicians were limited to therapies with suboptimal efficacy and intolerable toxicity until the FDA approved ceftazidime-avibactam and meropenem-vaborbactam, adding two essential pharmacotherapies to our antibiotic armamentarium. These agents display superior efficacy and safety compared to historical treatment options; however, resistance has already been reported. Several antimicrobials currently in the drug pipeline exhibit early promise and may fill needed gaps in therapy. Areas covered: This article encompasses both the past and present treatment options for the management of KPC-producing bacterial infections via an extensive review and critical appraisal of the current literature. Expert opinion: Traditional treatment options can no longer be recommended as first-line options for the management of KPC-producing bloodstream infections. Ceftazidime-avibactam or meropenem-vaborbactam plus or minus an aminoglycoside or polymyxin should be utilized as backbone therapies given their superior efficacy and safety profiles when compared to traditional treatment options. For susceptible KPC-producing urinary tract infections, it is reasonable to consider treatment with an aminoglycoside or with fosfomycin as a monotherapy. All of these decisions should be based on patient-specific characteristics, severity of infection and source control, susceptibility patterns, and input from infectious diseases experts.

Treatment options and clinical outcomes for carbapenem-resistant Enterobacteriaceae bloodstream infection in a Chinese university hospital

BACKGROUND

Carbapenem resistant Enterobacteriaceae (CRE) has become a serious public health problem. Limited information is available about the treatment options that physicians used to fight CRE infections and related clinical outcomes in China. The aim of the present study was to explore the treatment options and clinical outcomes of patients with CRE bloodstream infection (BSI) in a Chinese teaching hospital.

METHODS

A retrospective study was conducted during 2011 to 2015 in one Chinese teaching hospital. Demographic, microbiological and clinical characteristics of enrolled subjects were collected from medical records. Data were analyzed by Kaplan-Meier graphs, log-rank test, and Cox regression.

RESULTS

A total of 98 inpatients with CRE BSI were enrolled in this study. For empirical therapy, 26 patients (26.5%) received at least one active drug within 48h after the onset of bacteremia. For definitive treatment, 59.2% (49/82) patients received at least one active drug and 40.2% (33/82) patients received therapy with no active drug. The overall 30-day mortality was 53.1% (52/98). Adverse outcome appeared to be more likely among patients with previous carbapenem exposure, neutropenia, severity of septic and time to initiation of BSIs. There was no significant difference in the mortality between the two groups of patients with combination therapy versus monotherapy (p=0.105). Severity of sepsis and neutropenia were identified as independent predictors of mortality.

CONCLUSIONS

Our study demonstrated a high mortality associated with CRE BSI and a high percentage of inappropriate empirical treatment for CRE BSI patients in a Chinese teaching hospital. Particular attention should be given to the patients with CRE BSI.

Trends in Antimicrobial Resistance against Enterobacteriaceae Strains Isolated from Blood: A 10-year Epidemiological Study in Mainland China (2004-2014)

Background:

Antimicrobial resistance is a serious problem that compromises the empirical treatment of infections, resulting in a lack of effective antibiotics and high medical expenses. Here, we aimed to monitor the trends in antimicrobial resistance among Enterobacteriaceae isolated from blood samples in mainland China.

Methods:

A total of 2240 Enterobacteriaceae isolates from blood were collected from hospitalized patients at 19 tertiary hospitals between October 2004 and June 2014. The minimum inhibitory concentrations of all isolates were determined using the agar dilution method according to the Clinical and Laboratory Standards Institute 2016 guidelines.

Results:

The most commonly isolated bacteria were Escherichia coli, compromising 47.0% (1053/2240) of the total isolates, followed by Klebsiella spp. (26.3%), Salmonella spp. (10.4%), and Enterobacter spp. (9.2%). The detection rates of extended-spectrum β-lactamases (ESBLs) among E. coli were 68.9% (2004–2005), 73.2% (2007–2008), 67.9% (2009–2010), 72.6% (2011–2012), and 58.4% (2013–2014), whereas those in ESBL-producing Klebsiella pneumoniae were slightly decreased (75.9%, 50.0%, 41.4%, 40.2%, and 43.0%, respectively). Carbapenems were the most potent agents against the Enterobacteriaceae isolates, followed by moxalactam, tigecycline, and amikacin. However, there was a decrease in the susceptibility rates for carbapenems in all species, particularly K. pneumoniae (decreased by 10.6% for imipenem) and Enterobacter aerogenes (decreased by 21.1% for imipenem). Reviving antibiotics (tigecycline and polymyxins) showed good in vitro activity against Enterobacteriaceae.

Conclusions:

The activity of antibiotics against Enterobacteriaceae isolated from blood was decreased overall. Large proportions of ESBL-producing isolates were identified among E. coli and Klebsiella spp. Carbapenem-resistant isolates have become a major challenge in the treatment of infections.

Factors associated to prevalence and treatment of carbapenem-resistant Enterobacteriaceae infections: a seven years retrospective study in three tertiary care hospitals

Background

The increasing incidence of carbapenem-resistant Enterobacteriaceae (CRE), has resulted in a difficult problem in the current clinical anti-infective treatment. We performed a retrospective analysis of prevalence and treatment for CRE infections patients.

Methods

This study was conducted in three tertiary care hospitals from January 1, 2010 to December 30, 2016. Baseline data, treatment, and outcomes were collected in patients with ventilator-associated bacterial pneumonia (VABP), bacteremia, complicated urinary tract infection (cUTI)/acute pyelonephritis (AP), hospital-acquired bacterial pneumonia (HABP), superficial wound infection (SWI), biliary tract infection (BTI), deep wound infection (DWI) and sterile body fluids infection (SBFI) due to CRE.

Results

One hundred twenty-four cases of CRE infection were identified: 31 VABP, 22 bacteremia, 18 cUTI/AP, 16 HABP, 16 SWI, 9 BTI, 7 DWI and 5 SBFI. The patient population had significant immunocompromised (33 of 124, 26.6%) and severe sepsis (43 of 124, 34.7%). The most common CRE pathogens were Klebsiella pneumoniae (84 of 124, 67.7%) and Enterobacter cloacae (24 of 124, 19.4%). And the production of IMP-type carbapenemase was the main antibiotic resistance mechanism. The majority of patients to take monotherapy for empiric therapy and dual therapy for direct treatment. Outcomes were universally poor (28-day mortality was 22.6%, 28 of 124) across all sites of infection.

Conclusions

We identified a large number of cases of CRE infection in 7 years from different parts, most of these pathogens have been confirmed to produce IMP-type carbapenemases. The retrospective analysis of cases of such bacterial infections will help to control future infections of these pathogens. Despite the high mortality rate, we still found that the selection of quinolone antibiotics can be effective in the treatment of CRE producing IMP type enzymes.

Risk Factors for Carbapenem-Resistant Klebsiella pneumoniae Infection: A Meta-Analysis

AIMS

Carbapenem-resistant Klebsiella pneumoniae (CRKP) infection has been rapidly emerging as a life-threatening nosocomial disease in many countries. However, studies on the corresponding risk factors of CRKP infection showed inconsistent results. To resolve these inconsistencies, we conducted a meta-analysis of previous studies on the potential risk factors of CRKP infection. The results of this study could be used to develop CRKP infection prevention strategies.

METHODS

Relevant works were systematically searched from five electronic databases up to September 2016. Z-test was used to determine the significance of the pooled odds ratios (ORs). ORs and 95% confidence intervals were utilized to compare the risk factors of CRKP infection.

RESULTS

Sixteen studies that involved 3,627 participants were included in the meta-analysis. We identified the following risk factors that were associated with CRKP infection: (1) longer length of hospital stay (LOS) (OR = 12.92), (2) admission to intensive care unit (ICU) (OR = 2.48), (3) prior hospitalization (OR = 1.85), (4) longer days of ICU stay (OR = 4.58), (5) transplant recipient (OR = 2.01), (6) steroid use (OR = 1.43), (7) central venous catheter use (OR = 2.30), (8) mechanical ventilation (OR = 2.54), (9) presence of tracheostomy (OR = 3.63), (10) parenteral nutrition (OR = 2.38), (11) previous antibiotic use (OR = 3.31), and (12) exposure to carbapenems (OR = 4.01), (13) aminoglycosides (OR = 2.05), (14) glycopeptides (OR = 2.40), (15) quinolones (OR = 2.28), and (16) anti-pseudomonal penicillins (OR = 2.67).

CONCLUSIONS

Sixteen risk factors including longer LOS, admission to ICU, previous antibiotic use, and exposure to carbapenems were associated with the development of CRKP infection. Identification of modifiable risk factors could play an important role in the prevention of CRKP infection.

High-dose tigecycline for the treatment of nosocomial carbapenem-resistant Klebsiella pneumoniae bloodstream infections: A retrospective cohort study

Carbapenem-resistant Klebsiella pneumoniae (CRKP) bloodstream infection (BSI) has become increasingly frequent threat recently, especially in the intensive care unit (ICU). High-dose tigecycline (TGC) regimen is proposed due to the limitation of treatment options. We investigated the efficacy and safety of high-dose TGC combination regimens for treating CRKP BSI. Furthermore, the risk factors for mortality were also determined.This was a single center retrospective cohort study conducted from 2014 to 2016. A total of 40 patients with nosocomial CRKP BSI admitted to the ICU were included; they were classified into two groups according to the treatment regimens with high-dose TGC (HD group) or not (non-HD group). In-hospital mortality rates and microbiologic responses from both groups were reviewed and compared. Besides, the survival and non-survival groups were compared to identify the risk factors of mortality.Twenty-three patients constituted the HD group (high-dosage TGC regimen was administered as 200 mg loading dose followed by 100 mg every 12 h) and 17 patients constituted the non-HD group (standard dose TGC therapy as 100 mg loading dose followed by 50 mg every 12 h and other antibiotics). The in-hospital mortality was 52.2% in the HD group and 76.5% in the non-HD group (P = .117). The Kaplan-Meier test showed significantly longer survival times in the HD group (mean: 83 days vs 28 days; P = .027). Microbiological eradication was observed in 13 patients (56.5%) in the HD group and 6 patients (36.3%) in the non-HD group (P = .184). A smaller fraction of patients in the HD group were subjected to vasoactive therapy (52.2% vs 88.2%; P = .016) compared to the non-HD group. There was no significant difference in the manifestation of adverse effects between the two groups. In the multivariate analysis, multiple organ dysfunction syndrome (MODS), vasoactive therapy, and exposure to carbapenems were regarded as the independent predictors of mortality.A therapeutic regimen consisting of a high dose of TGC was associated with significantly longer survival time and numerically lower mortality in CRKP BSI. Adverse events were not increased with the double dose therapy.

Determining β-lactam exposure threshold to suppress resistance development in Gram-negative bacteria

Objectives

β-Lactams are commonly used for nosocomial infections and resistance to these agents among Gram-negative bacteria is increasing rapidly. Optimized dosing is expected to reduce the likelihood of resistance development during antimicrobial therapy, but the target for clinical dose adjustment is not well established. We examined the likelihood that various dosing exposures would suppress resistance development in an in vitro hollow-fibre infection model.

Methods

Two strains of Klebsiella pneumoniae and two strains of Pseudomonas aeruginosa (baseline inocula of ∼10 8  cfu/mL) were examined. Various dosing exposures of cefepime, ceftazidime and meropenem were simulated in the hollow-fibre infection model. Serial samples were obtained to ascertain the pharmacokinetic simulations and viable bacterial burden for up to 120 h. Drug concentrations were determined by a validated LC-MS/MS assay and the simulated exposures were expressed as C min /MIC ratios. Resistance development was detected by quantitative culture on drug-supplemented media plates (at 3× the corresponding baseline MIC). The C min /MIC breakpoint threshold to prevent bacterial regrowth was identified by classification and regression tree (CART) analysis.

Results

For all strains, the bacterial burden declined initially with the simulated exposures, but regrowth was observed in 9 out of 31 experiments. CART analysis revealed that a C min /MIC ratio ≥3.8 was significantly associated with regrowth prevention (100% versus 44%, P  = 0.001).

Conclusions

The development of β-lactam resistance during therapy could be suppressed by an optimized dosing exposure. Validation of the proposed target in a well-designed clinical study is warranted.

Gram-Negative Bacterial Infections: Research Priorities, Accomplishments, and Future Directions of the Antibacterial Resistance Leadership Group

Antimicrobial resistance in pathogenic gram-negative bacteria is one of the most pressing challenges in the field of infectious diseases and is one of 4 key areas of unmet medical need identified by the Antibacterial Resistance Leadership Group (ARLG). The mission of the Gram-Negative Committee is to advance our knowledge of these challenging infections and implement studies to improve patient outcomes. Studies have fallen primarily into 2 broad categories: prospective cohort studies and interventional trials. Among the observational studies, CRACKLE (Consortium on Resistance Against Carbapenems in Klebsiella pneumoniae and Other Enterobacteriaceae) has contributed seminal multicenter data describing risk factors and clinical outcomes of carbapenem-resistant Enterobacteriaceae (CRE) in sentinel US hospitals. Building on this success, CRACKLE II will expand the network to hospitals across the United States and Colombia. Similar protocols have been proposed to include Acinetobacter baumannii and Pseudomonas aeruginosa (SNAP and POP studies). In addition, the CREST study (Carbapenem-Resistant Enterobacteriaceae in Solid Organ Transplant Patients) has provided pivotal data on extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae and CRE carriage among solid organ transplant recipients to inform management of this vulnerable patient population. Two clinical trials to define novel ways of using an existing antibiotic, fosfomycin, to treat ESBL-producing Enterobacteriaceae (one that has completed enrollment and the other in late protocol development) will determine the clinical efficacy of fosfomycin as step-down oral therapy to treat complicated urinary tract infections. Additional clinical studies and trials using immunotherapeutic or newly approved agents are also in the planning stage, with the main goals of generating actionable data that will inform clinical decision making and facilitate development of new treatment options for highly resistant gram-negative bacterial infections.

Carbapenem Resistance: A Review

Carbapenem resistance is a major and an on-going public health problem globally. It occurs mainly among Gram-negative pathogens such as Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii, and may be intrinsic or mediated by transferable carbapenemase-encoding genes. This type of resistance genes are already widespread in certain parts of the world, particularly Europe, Asia and South America, while the situation in other places such as sub-Saharan Africa is not well documented. In this paper, we provide an in-depth review of carbapenem resistance providing up-to-date information on the subject.

Readmissions With Multidrug-Resistant Infection in Patients With Prior Multidrug Resistant Infection

OBJECTIVE To determine incidence of and risk factors for readmissions with multidrug-resistant organism (MDRO) infections among patients with previous MDRO infection. DESIGN Retrospective cohort of patients admitted between January 1, 2006, and October 1, 2015. SETTING Barnes-Jewish Hospital, a 1,250-bed academic tertiary referral center in St Louis, Missouri. METHODS We identified patients with MDROs obtained from the bloodstream, bronchoalveolar lavage (BAL)/bronchial wash, or other sterile sites. Centers for Disease Control and prevention (CDC) and European CDC definitions of MDROs were utilized. All readmissions ≤1 year from discharge from the index MDRO hospitalization were evaluated for bloodstream, BAL/bronchial wash, or other sterile site cultures positive for the same or different MDROs. RESULTS In total, 4,429 unique patients had a positive culture for an MDRO; 3,453 of these (78.0%) survived the index hospitalization. Moreover, 2,127 patients (61.6%) were readmitted ≥1 time within a year, for a total of 5,849 readmissions. Furthermore, 512 patients (24.1%) had the same or a different MDRO isolated from blood, BAL/bronchial wash, or another sterile site during a readmission. Bone marrow transplant, end-stage renal disease, lymphoma, methicillin-resistant Staphylococcus aureus, or carbapenem-resistant Pseudomonas aeruginosa during index hospitalization were factors associated with increased risk of having an MDRO isolated during a readmission. MDROs isolated during readmissions were in the same class of MDRO as the index hospitalization 9%-78% of the time, with variation by index pathogen. CONCLUSIONS Readmissions among patients with MDRO infections are frequent. Various patient and organism factors predispose to readmission. When readmitted patients had an MDRO, it was often a pathogen in the same class as that isolated during the index admission, with the exception of Acinetobacter (~9%). Infect Control Hosp Epidemiol 2018;39:12-19.