Hidden threats in the plastisphere: Carbapenemase-producing Enterobacterales colonizing microplastics in river water

Carbapenem resistance poses a significant burden on healthcare systems worldwide. Microplastics (MPs) have emerged as potential contributors to antibiotic resistance spread in the environment. However, the link between MPs and carbapenem resistance remains unexplored. We investigated the prevalence of carbapenem-resistant bacteria colonizing MPs placed in a river. Three replicates of a mixture of polypropylene (PP), polyethylene (PE) and polyethylene terephthalate (PET) and of PET alone were placed both upstream and downstream a wastewater treatment plant (WWTP) discharge. Carbapenem-resistant Enterobacterales (CRE) were further characterized by phenotypic tests and whole-genome sequencing. The abundance of carbapenem-resistant bacteria on MPs increased significantly downstream the WWTP. Their prevalence was higher in the MPs mixture compared to PET alone. CRE strains colonizing MPs included Klebsiella pneumoniae (n = 3), Klebsiella quasipneumoniae (n = 3), Raoultella ornithinolytica (n = 2), Enterobacter kobei (n = 1) and Citrobacter freundii (n = 1), most (n = 8) recovered after the WWTP discharge. All strains exhibited at least one of the tested virulence traits (biofilm formation at 37 °C, haemolytic activity and siderophore production), were multi-drug resistant and carried carbapenemase-encoding genes [blaKPC-3 (n = 5), blaGES-5 (n = 2) or blaKPC-3 + blaGES-5 (n = 3)]. Uncommon phenotypes of resistance to imipenem/relebactam (n = 3) and ceftazidime/avibactam (n = 2) were observed. Two blaKPC-3-positive K. pneumoniae successfully transfer this gene trough conjugation. Genome analysis predicted all strains as human pathogens. The blaKPC-3 was associated with the Tn4401d transposon on a pBK30683-like plasmid in most of the isolates (n = 7). The blaGES-5 was mostly linked to class 3 integrons. A K. pneumoniae strain belonging to the outbreak-causing high-risk clone ST15 carried both blaKPC-3 and blaCTX-M-15. Two K. quasipneumoniae isolates carried the plasmid-mediated colistin resistance gene mcr-9. Our results underscore the role of MPs as vectors for CRE dissemination, particularly following WWTPs discharges. MPs may act as carriers, facilitating the dissemination of carbapenemase-encoding genes and potentially contributing to increased CRE incidence in the environment.

Antimicrobial Use and Carbapenem-Resistant Enterobacterales in Korea: A Nationwide Case-Control Study With Propensity Score Matching

BACKGROUND

Nationwide research on the association between carbapenem-resistant Enterobacterales (CREs) and antibiotic use is limited.

METHODS

This nested case-control study analyzed Korean National Health Insurance claims data from April 2017 to April 2019. Based on the occurrence of CRE, hospitalized patients aged ≥ 18 years were classified into CRE (cases) and control groups. Propensity scores based on age, sex, modified Charlson comorbidity score, insurance type, long-term care facility, intensive care unit stay, and acquisition of vancomycin-resistant Enterococci were used to match the case and control groups (1:3).

RESULTS

After matching, the study included 6,476 participants (1,619 cases and 4,857 controls). Multivariable logistic regression analysis revealed that the utilization of broad-spectrum antibiotics, such as piperacillin/tazobactam (adjusted odds ratio [aOR], 2.178; 95% confidence interval [CI], 1.829-2.594), third/fourth generation cephalosporins (aOR, 1.764; 95% CI, 1.514-2.056), and carbapenems (aOR, 1.775; 95% CI, 1.454-2.165), as well as the presence of comorbidities (diabetes [aOR, 1.237; 95% CI, 1.061-1.443], hemiplegia or paraplegia [aOR, 1.370; 95% CI, 1.119-1.679], kidney disease [aOR, 1.312; 95% CI, 1.105-1.559], and liver disease [aOR, 1.431; 95% CI, 1.073-1.908]), were significantly associated with the development of CRE. Additionally, the CRE group had higher mortality (8.33 vs. 3.32 incidence rate per 100 person-months, P < 0.001) and a total cost of healthcare utilization per person-month (15,325,491 ± 23,587,378 vs. 5,263,373 ± 14,070,118 KRW, P < 0.001) than the control group.

CONCLUSION

The utilization of broad-spectrum antibiotics and the presence of comorbidities are associated with increasing development of CRE. This study emphasizes the importance of antimicrobial stewardship in reducing broad-spectrum antibiotic use and CRE disease burden in Korea.

Oxidized glutathione reverts carbapenem resistance in blaNDM-1-carrying Escherichia coli

The emergence of drug-resistant Enterobacteriaceae carrying plasmid-mediated β-lactamase genes has become a significant threat to public health. Organisms in the Enterobacteriaceae family containing New Delhi metallo-β-lactamase‑1 (NDM-1) and its variants, which are capable of hydrolyzing nearly all β-lactam antibacterial agents, including carbapenems, are referred to as superbugs and distributed worldwide. Despite efforts over the past decade, the discovery of an NDM-1 inhibitor that can reach the clinic remains a challenge. Here, we identified oxidized glutathione (GSSG) as a metabolic biomarker for blaNDM-1 using a non-targeted metabolomics approach and demonstrated that GSSG supplementation could restore carbapenem susceptibility in Escherichia coli carrying blaNDM-1 in vitro and in vivo. We showed that exogenous GSSG promotes the bactericidal effects of carbapenems by interfering with intracellular redox homeostasis and inhibiting the expression of NDM-1 in drug-resistant E. coli. This study establishes a metabolomics-based strategy to potentiate metabolism-dependent antibiotic efficacy for the treatment of antibiotic-resistant bacteria.

Molecular analysis of metallo-beta-lactamase-producing Pseudomonas aeruginosa in Switzerland 2022-2023

OBJECTIVES

The occurrence of metallo-beta-lactamase-producing Pseudomonas aeruginosa (MBL-PA) isolates is increasing globally, including in Switzerland. The aim of this study was to characterise, phenotypically and genotypically, the MBL-PA isolates submitted to the Swiss National Reference Center for Emerging Antibiotic Resistance (NARA) reference laboratory over a 12-month period from July 2022 to July 2023.

METHODS

Thirty-nine non-duplicate MBL-PA Isolates were submitted to NARA over the study period from across Switzerland. Susceptibility was determined by broth microdilution according to EUCAST methodology. Whole-genome sequencing was performed on 34 isolates. Sequence types (STs) and resistance genes were ascertained using the Centre for Genomic Epidemiology platform. MBL genes, blaNDM-1, blaIMP-1, and blaVIM-2, were cloned into vector pUCP24 and transformed into P. aeruginosa PA14.

RESULTS

The most prevalent MBL types identified in this study were VIM (21/39; 53.8%) followed by NDM (11/39; 28.2%), IMP (6/39; 15.4%), and a single isolate produced both VIM and NDM enzymes. WGS identified 13 different STs types among the 39 isolates. They all exhibited resistance to cephalosporins, carbapenems, and the beta-lactam-beta-lactamase inhibitor combinations, ceftolozane-tazobactam, ceftazidime-avibactam, imipenem-relebactam, and meropenem-vaborbactam, and 8 isolates were cefiderocol (FDC) resistant. Recombinant P. aeruginosa strains producing blaNDM-1, blaIMP-1, and blaVIM-2 exhibited FDC MICs of 16, 8, and 1 mg/L, respectively.

CONCLUSIONS

This study showed that the MBL-PA in Switzerland could be attributed to the wide dissemination of high-risk clones that accounted for most isolates in this study. Although FDC resistance was only found in 8 isolates, MBL carriage was shown to be a major contributor to this phenotype.

An extensively drug-resistant Pseudomonas aeruginosa isolate from Myanmar

OBJECTIVES

Antimicrobial resistance (AMR) including multidrug-resistant (MDR) and extensively drug-resistant (XDR) Pseudomonas aeruginosa has emerged as one of the serious public health threats across the globe. Southeast Asia is a 'hot spot' of antimicrobial-resistant bacteria, including MDR P. aeruginosa. Despite Myanmar being located in Southeast Asia and suffering from a high infectious disease burden, data on MDR and XDR P. aeruginosa from Myanmar are limited. In this communication, we report the draft genome of an XDR P. aeruginosa isolate, MMXDRPA001, that was identified during a routine diagnosis in Myanmar.

METHODS

An MMXDRPA001 isolate colonising a hospitalised patient was characterised by antibiotic resistance profiling following standard methods and whole-genome sequencing using an Illumina MiSeq platform. The generated reads were de novo assembled using SPAdes (v.3.9.1). Annotation was performed by Prokka (v.1.14.0). Sequence type, antimicrobial resistance and virulence-related genes were predicted from the sequence. The phylogenetic relationships of all P. aeruginosa isolates were determined using core genome single-nucleotide polymorphisms (SNPs) analysis utilising Snippy (v.4.6.0) and Gubbins (v.2.3.4).

RESULTS

P. aeruginosa MMXDRPA001 was resistant to most antipseudomonal β-lactams, aminoglycosides and quinolones. The assembly comprised 145 contigs totalling 6 808 493 bases of sequence and a total of 6183 coding sequences. The isolate belonged to sequence type (ST) 235, contained carbapenemase-encoding gene blaIMP-1 and was clonally related to a previously reported isolate from Thailand.

CONCLUSION

The identification of an international high-risk clone of ST235 XDR isolate in Myanmar, genomically relating to that from a neighbouring country underscores the need for coordinated AMR surveillance throughout healthcare settings in Myanmar and in the Southeast Asia region.

Comparative effectiveness of cefmetazole versus carbapenems and piperacillin/tazobactam as initial therapy for bacteremic acute cholangitis: A retrospective study

INTRODUCTION

Carbapenems and piperacillin/tazobactam (PIPC/TAZ) are commonly used as the initial therapy to treat extended-spectrum β-lactamase (ESBL)-producing Enterobacterales in acute cholangitis. However, the overuse of these antibiotics contributes to the spread of antimicrobial resistance. Cefmetazole (CMZ) is stable to hydrolysis by ESBLs, so it may be an alternative to carbapenems and PIPC/TAZ. However, the effectiveness of CMZ compared with that of carbapenems and PIPC/TAZ as the initial therapy for acute cholangitis is unknown.

METHODS

We conducted a retrospective cohort study at a university hospital between April 1, 2014, and December 31, 2022. Patients with bacteremic acute cholangitis who received CMZ, carbapenems, or PIPC/TAZ as the initial therapy were included. The patients were divided into a CMZ group and a carbapenems or PIPC/TAZ (CP) group to compare patient outcomes.

RESULTS

A total of 99 patients (54 in the CMZ group and 45 in the CP group) were analyzed. The baseline characteristics of the patients were similar and 30-day mortality did not differ between groups (4% vs. 7%, P = 0.66). However, the CMZ group had a shorter length of stay (LOS) (8 days vs. 15 days, P < 0.001) and lower mean antibiotic cost (98.92 USD vs. 269.49 USD, P < 0.001) than the CP group.

CONCLUSIONS

In bacteremic acute cholangitis, initial therapy with CMZ may contribute to a shorter LOS and lower antibiotic costs than treatment with carbapenems and PIPC/TAZ, without worsening patient outcomes.

Clinical characteristics and risk factors for neonatal bloodstream infection due to carbapenem-resistant Enterobacteriaceae: A single-centre Chinese retrospective study

OBJECTIVES

To analyse the clinical characteristics and risk factors for bloodstream infections (BSIs) caused by carbapenem-resistant Enterobacteriaceae (CRE) in neonates.

METHODS

This single-centre, retrospective study included all patients with BSIs admitted to a neonatal intensive care unit between 1 January 2015 and 30 April 2022. The clinical and microbiological data of patients were collected; predictors of 30-day mortality in patients with CRE BSIs were also identified in this study.

RESULTS

Among the 224 neonates with Enterobacteriaceae BSIs, 39.29% (88/224) of the patients developed CRE BSIs. The 30-day mortality rate reached up to 21.59% (19/88). The Quick Sequential Organ Failure Assessment score > 2 (odds ratio [OR] and 95% credibility interval [CI]: 3.852 [1.111-13.356], P < 0.05), prior to more than two kinds of antibiotics use (OR and 95% CI: 9.433 [1.562-56.973], P < 0.05), pneumonia (OR and 95% CI: 3.847 [1.133-13.061], P < 0.05), and caesarean section (OR and 95% CI: 2.678 [1.225-5.857], P < 0.05) were independent risk factors associated with CRE BSIs. Moreover, the risk factors for mortality in neonates with CRE BSIs were significantly associated with neonatal Sequential Organ Failure Assessment score > 6 (OR and 95% CI: 16.335 [1.446-184.517], P < 0.05).

CONCLUSION

Prior to more than two kinds of antibiotics use, Quick Sequential Organ Failure Assessment score > 2, pneumonia and caesarean section were independent risk factors for CRE BSIs. The Neonatal Sequential Organ Failure Assessment score > 6 was a risk factor for mortality associated with CRE BSIs.

Prolonged versus intermittent β-lactam infusion in sepsis: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

The two latest studies on prolonged versus intermittent use of β-lactam antibiotics in patients with sepsis did not reach consistent conclusions, further contributing to the controversy surrounding the effectiveness of the prolonged β-lactam antibiotics infusion strategy. We conducted a systemic review and meta-analysis to evaluate the efficacy and safety of prolonged and intermittent β-lactam infusion in adult patients with sepsis.

METHODS

We systematically searched PubMed, EMBASE, and Cochrane Library databases for original randomized controlled trials comparing prolonged and intermittent β-lactam infusion in sepsis patients. A random-effects model was used to evaluate mortality, clinical success, microbiological success, and adverse events. We also conducted subgroup analyses to explore the impact of various factors on the mortality rates. Relative risk (RR) and corresponding 95% confidence intervals (CIs) were used to calculate the overall effect sizes for dichotomous outcomes. This meta-analysis was registered in PROSPERO (CRD42023463905).

RESULTS

We assessed 15 studies involving 2130 patients. In our comprehensive assessment, we found a significant reduction in all-cause mortality (RR, 0.83; 95% CI 0.72-0.97; P = 0.02) and a notable improvement in clinical success (RR, 1.16; 95% CI 1.03-1.31; P = 0.02) in the prolonged infusion group compared to the intermittent infusion group, whereas microbiological success did not yield statistically significant results (RR, 1.10; 95% CI 0.98-1.23; P = 0.11). No significant differences in adverse events were observed between the two groups (RR, 0.91; 95% CI 0.64-1.29; P = 0.60). Additionally, remarkable conclusions were drawn from subgroup analyses including studies with sample sizes exceeding 20 individuals per group (RR, 0.84; 95%CI 0.72-0.98; P = 0.03), research conducted post-2010 (RR, 0.84; 95%CI 0.72-0.98; P = 0.03), cases involving infections predominantly caused by Gram-negative bacteria (RR, 0.81; 95%CI 0.68-0.96; P = 0.02), as well as the administration of a loading dose (RR, 0.84; 95% CI 0.72-0.97; P = 0.02) and the use of penicillin (RR, 0.61; 95% CI 0.38-0.98; P = 0.04).

CONCLUSIONS

Compared to intermittent infusion, prolonged infusion of β-lactam antibiotics significantly decreases all-cause mortality among patients with sepsis and enhances clinical success without increasing adverse events.

Simultaneous determination of five carbapenems, highly polar antibiotics, in milk by LC-MS/MS

The simultaneous determination of five carbapenems (biapenem, doripenem, ertapenem, imipenem, and meropenem) in raw and pasteurised bovine milk samples using LC-MS/MS was achieved and validated. Chromatographic separation was conducted on an InertSustain® AQ-C18 column using 0.1% formic acid in water and acetonitrile as the mobile phase. Target compounds were extracted using acetonitrile/water (20:80, v/v). After the removal of lipids with acetonitrile-saturated hexane, the dissolved protein was denatured with acetic acid. A portion of the supernatant was passed through an Oasis® PRiME HLB cartridge to remove the matrix. This novel method was validated in accordance with the Japanese validation guidelines and exhibited good trueness, ranging from 86.3% to 96.2%, using matrix-matched calibration curves. The relative standard deviation of repeatability ranged from 1.0% to 6.3%, and that of within-laboratory reproducibility ranged from 1.6% to 7.1%. The limit of quantification was 1.0 µg kg-1 for all analytes. None of the 60 milk samples commercially available in Tokyo contained any analytes. This novel method exhibited high-quality performance and can easily be implemented for the routine monitoring of carbapenems, which are highly polar antibiotics in milk.

Evaluation of intermittent antimicrobial infusion documentation practices in intensive care units: A cross-sectional study

OBJECTIVE

To observe nurse administration of carbapenem antibiotics, in the context of medication safety measures, in intensive care units.

RESEARCH METHODOLOGY/DESIGN

A quantitative study was conducted using observation principles.

SETTING

Three adult private and public Intensive Care Units in the health district of a capital city in KwaZulu-Natal, South Africa.

MAIN OUTCOME MEASURES

Nurse practices were observed for double-checking of the medication order, medication vial, and method of preparation and administration. Infusion bags were inspected for nurse labelling of medication and patient details. Patient medication treatment charts were inspected for nurse signature.

RESULTS

Carbapenem infusion administrations (n = 223) to twenty patients were observed. Adherence to the scheduled time occurred in 34.9% administrations, 5.4% doses were not given, and an incorrect dose given on 1.4% administrations. One hundred and forty-four (64.6%) infusion bags were inspected during the administrations: there was no medication label affixed to 21.5% bags, and only 8.3% of bags were labelled with essential details; the patient's name, drug, dose, date, time, signature of the nurse mixing and administering the dose, and signature of the secondary nurse.

CONCLUSION

There was a lack of compliance with accepted medication risk mitigation measures. Sub-optimal double-checking resulted in the incorrect dose given, missed dose, and non-adherence to scheduled administration time. This has implications for the optimal administration of antimicrobial medications, raising concerns about the efficacy of treatment for critically ill patients.

IMPLICATIONS FOR CLINICAL PRACTICE

Parenteral administration errors pose a challenge in acute care areas. Risk mitigation measures include double-checking of medications. If antimicrobial treatment is not administered at the prescribed dosing intervals, this may have implications for the efficacy of time-dependent broad-spectrum antibiotics such as carbapenems. Medication administration errors involving antimicrobial medications should therefore be considered as high-risk errors, with the potential to contribute towards antimicrobial resistance.

Expansion of healthcare-associated hypervirulent KPC-2-producing Klebsiella pneumoniae ST11/KL64 beyond hospital settings

The spread of carbapenemase-producing Klebsiella pneumoniae beyond hospital settings is a global critical issue within a public health and One Health perspective. Another worrisome concern is the convergence of virulence and resistance in healthcare-associated lineages of K. pneumoniae leading to unfavorable clinical outcomes. During a surveillance study of WHO critical priority pathogens circulating in an impacted urban river in São Paulo, Brazil, we isolate two hypermucoviscous and multidrug-resistant K. pneumoniae strains (PINH-4250 and PINH-4900) from two different locations near to medical centers. Genomic investigation revealed that both strains belonged to the global high-risk sequence type (ST) ST11, carrying the bla_KPC-2 carbapenemase gene, besides other medically important antimicrobial resistance determinants. A broad virulome was predicted and associated with hypervirulent behavior in the Galleria mellonella infection model. Comparative phylogenomic analysis of PINH-4250 and PINH-4900 along to an international collection of publicly available genomes of K. pneumoniae ST11 revealed that both environmental strains were closely related to hospital-associated K. pneumoniae strains recovered from clinical samples between 2006 and 2018, in São Paulo city. Our findings support that healthcare-associated KPC-2-positive K. pneumoniae of ST11 clone has successfully expanded beyond hospital settings. In summary, aquatic environments can become potential sources of international clones of K. pneumoniae displaying carbapenem resistance and hypervirulent behaviors, which is a critical issue within a One Health perspective.

Impact of carbapenem-targeted antimicrobial stewardship interventions: an interrupted time-series analysis

BACKGROUND

The development of carbapenem-resistant Gram-negative bacilli (CR-GNB) is largely favoured by indiscriminate and prolonged carbapenem use, which is a significant contributing factor.

AIM

To evaluate the impact of two carbapenem antibiotic stewardship programme interventions on both carbapenem prescriptions and the clinical isolation rates of CR-GNBs, using interrupted time-series analysis.

METHODS

A time-series analysis was performed using data for carbapenem usage from a tertiary hospital in South Korea from January 2017 to July 2022. Two carbapenem antibiotic stewardship programme interventions were implemented sequentially: (i) a prospective audit and feedback (PAF) from November 2018 to April 2020 (intervention 1), and (ii) preauthorization from May 2020 to August 2020 (intervention 2). Monthly carbapenem usage and incidence of CR-GNB before and after each intervention were compared using an autoregressive integrated moving average model.

FINDINGS

Implementation of PAF resulted in a significant reduction in carbapenem consumption, followed by an additional decrease after the preauthorization was implemented. The incidence of carbapenem-resistant Escherichia coli and Klebsiella pneumoniae increased after intervention 1, but there was a significant change from an increasing trend to a stationary trend after intervention 2. The incidence of carbapenem-resistant Pseudomonas aeruginosa, which had increased during the baseline period, became stationary after intervention 1. A significant decrease was observed in the incidence of carbapenem-resistant Acinetobacter baumannii during the implementation of intervention 1 and 2.

CONCLUSION

This study emphasizes the importance of adopting comprehensive antibiotic management and rigorous infection control to prevent infections caused by antibiotic-resistant bacteria.

Cefepime vs carbapenems for treating third-generation cephalosporin-resistant AmpC β-lactamase-hyperproducing Enterobacterales bloodstream infections: a multicenter retrospective study

OBJECTIVES

AmpC β-lactamase-hyperproducing Enterobacterales (ABLHE) bloodstream infections (BSI) are emerging and leading to therapeutic challenges worldwide. Prescriptions of carbapenems may lead to the emergence of resistance. This study aimed to compare cefepime with carbapenems for the treatment of third-generation cephalosporin-resistant ABLHE BSI.

METHODS

This retrospective multicenter study included patients with ABLHE BSI from two tertiary hospitals in France, between July 2017 and July 2022. Non-AmpC-producing Enterobacterales, extended-spectrum β-lactamase, and carbapenemase-producing Enterobacterales were excluded. Cefepime was prescribed only in case of minimal inhibitory concentration ≤1 mg/l. The primary outcome was 30-day in-hospital mortality from the date of index blood culture. Secondary outcomes were infection recurrence and treatment toxicity. An inverse probability of treatment weighting approach was used to balance the baseline characteristics between the two groups.

RESULTS

We analyzed 164 BSI, which included 77 in the cefepime group and 87 in the carbapenem group. In the weighted cohort, the 30-day mortality rates were similar between the cefepime group (23.3%) and the carbapenem group (19.6%) with a relative risk of 1.19 (95% confidence interval, 0.61-2.33 P = 0.614). No significant difference in recurrence or toxicity was found between the two groups.

CONCLUSION

This study adds evidence in favor of the use of cefepime for treating third-generation cephalosporin-resistant ABLHE BSI in case of minimal inhibitory concentration ≤ 1 mg/l, which could spare carbapenems.

The In vitro activity of carbapenems alone and in combination with β-lactamase inhibitors against difficult-to-treat mycobacteria; Mycobacterium tuberculosis, Mycobacterium abscessus, and Mycobacterium avium complex: A systematic review

Difficult-to-treat mycobacterial infections are increasing globally. There is an urgent need of new treatment alternatives for multidrug-resistant Mycobacterium tuberculosis (MTB), as well as nontuberculous mycobacteria such as the Mycobacterium abscessus complex (MABC) and Mycobacterium avium complex (MAC). Recently, new carbapenems and combinations of carbapenems with β-lactamase inhibitors have become available, but activity data in vitro against mycobacteria are so far scarce. Therefore, we performed a systematic review collating the minimum inhibitory concentrations (MICs) of carbapenems, with or without a β-lactamase inhibitors for MTB, MABC, and MAC. The databases PubMed and Web of Science were searched for the relevant articles in English up until September 21, 2022. Screening of studies was performed by two independent reviewers. MIC data by recommended methods with at least five individual MICs were included. Data were reported as MIC range, MIC50, modal MIC, and/or histograms when individual MICs were available. The study protocol was registered at PROSPERO (CRD42021258537). After screening, a total of 75 studies with MIC data for carbapenems with or without β-lactamase inhibitors were included in the review. For MTB, the oral carbapenem tebipenem combined with the β-lactamase inhibitor clavulanic acid resulted in the most significant reduction of MICs. For MABC, the addition of avibactam to tebipenem resulted in a 64-fold reduction of modal MIC. Data were insufficient for the analysis of MAC. Carbapenems, and in particular the novel oral compound tebipenem, in combination with clavulanic acid for MTB and avibactam for MABC may be an untapped potential for difficult-to-treat mycobacterial infections.

[New antibiotics for the treatment of urinary tract infections]

Urinary tract infections (UTIs) are among the most common bacterial infections. The clinical phenotypes of UTIs are heterogeneous, ranging from rather benign uncomplicated infections to complicated UTIs and pyelonephritis to severe urosepsis. Antibiotics have become indispensable in modern medicine, but the development of resistance is threatening clinical effectiveness. Antimicrobial resistance rates are locally high in UTIs, however can vary significantly depending on the population studied and the type of study. In addition, between 1990 and 2010, there was a discovery void in the development of new antibiotics that is still having an impact today. In recent years, UTIs have emerged as an infection model for research into novel antibiotics. In the last 10 years, novel gram-negative active drugs have been explored in these groups. On the one hand, novel beta-lactam/beta-lactamase inhibitor combinations were investigated, and there has also been further development of cephalosporins and aminoglycosides.

Carbapenem prescriptions: Compliance with guidelines in a pediatric hospital

BACKGROUND

This study aimed to describe the use of carbapenems in a pediatric tertiary center and to assess its compliance with national and local guidelines.

METHODS

This retrospective study focused on children who received at least one dose of carbapenems in a tertiary university hospital over a 1-year period (2019). The appropriateness of each prescription was assessed.

RESULTS

In total, 96 prescriptions were collected for 75 patients (median age 3 years [interquartile range, IQR: 0-9]). Most prescriptions were empirical (n = 77, 80%) and mainly concerned nosocomial infections (n = 69, 72%). At least one risk factor for extended-spectrum beta-lactamases was found in 48% (n = 46) of cases. The median duration of treatment with carbapenems was 5 days and it was over 7 days in 38% (n = 36) of cases. The use of carbapenems was considered appropriate in 95% (18/19) and 70% (54/77) of cases when therapy was guided by culture results or was empirical, respectively. De-escalation of carbapenem treatment within 72 h occurred in 31% (n = 30) of cases.

CONCLUSION

The use of carbapenems can be optimized in the pediatric population, even when the initial prescription for a carbapenem is considered appropriate.

Ceftazidime-avibactam with or without Aztreonam vs Polymyxin-based Combination Therapy for Carbapenem-resistant Enterobacteriaceae: A Retrospective Analysis

Introduction

Gram-negative sepsis remains one of the most difficult to treat infections in intensive care units (ICUs). Carbapenems are often considered to be robust and reliable options for treating infections due to Gram-negative bacteria. The dominance of carbapenem-resistant enterobacteriaceae (CRE) has emerged as one of the greatest challenges faced by the medical community today. Carbapenem-resistant enterobacteriaceae may be resistant to all beta lactam antimicrobials including carbapenems and often, are even resistant to other classes of drugs. There are limited studies comparing polymyxin-based therapies with ceftazidime-avibactam (CAZ-AVI)-based therapies for treating infections caused by CRE.

Methods

A retrospective study comparing outcomes between patients with bacteremia caused by CRE treated with polymyxin-based combination therapy and CAZ-AVI-based therapy (with or without aztreonam).

Results

Of total 104 patients, 78 (75%) were in the CAZ-AVI group. There was no significant difference in the underlying comorbidities between the two groups. The incidence of nephrotoxicity was significantly higher in the polymyxin group (p = 0.017). Ceftazidime-avibactam-based therapy was 66% less likely to be associated with day 14 mortality (p = 0.048) and 67% less likely to be associated with day 28 mortality (p = 0.039) as compared with polymyxin-based therapy.

Conclusion

Ceftazidime-avibactam-based therapy may be a superior option to polymyxin-based therapy for infections caused by CRE. This can have significant practical applications, in terms of optimizing therapy for the individual patient as well as sparing polymyxins and reducing the use of polymyxins in our hospitals.

How to cite this article

Prayag PS, Patwardhan SA, Panchakshari S, Sambasivam R, Dhupad S, Soman RN, et al. Ceftazidime-avibactam with or without Aztreonam vs Polymyxin-based Combination Therapy for Carbapenem-resistant Enterobacteriaceae: A Retrospective Analysis. Indian J Crit Care Med 2023;27(6):444-450.

Modelling interventions and contact networks to reduce the spread of carbapenem-resistant organisms between individuals in the ICU

BACKGROUND

Contact precautions are widely used to prevent the transmission of carbapenem-resistant organisms (CROs) in hospital wards. However, evidence for their effectiveness in natural hospital environments is limited.

OBJECTIVE

To determine which contact precautions, healthcare worker (HCW)-patient interactions, and patient and ward characteristics are associated with greater risk of CRO infection or colonization.

DESIGN, SETTING AND PARTICIPANTS

CRO clinical and surveillance cultures from two high-acuity wards were assessed through probabilistic modelling to characterize a susceptible patient's risk of CRO infection or colonization during a ward stay. User- and time-stamped electronic health records were used to build HCW-mediated contact networks between patients. Probabilistic models were adjusted for patient (e.g. antibiotic administration) and ward (e.g. hand hygiene compliance, environmental cleaning) characteristics. The effects of risk factors were assessed by adjusted odds ratio (aOR) and 95% Bayesian credible intervals (CrI).

EXPOSURES

The degree of interaction with CRO-positive patients, stratified by whether CRO-positive patients were on contact precautions.

MAIN OUTCOMES AND MEASURES

The prevalence of CROs and number of new carriers (i.e. incident CRO aquisition).

RESULTS

Among 2193 ward visits, 126 (5.8%) patients became colonized or infected with CROs. Susceptible patients had 4.8 daily interactions with CRO-positive individuals on contact precautions (vs 1.9 interactions with those not on contact precautions). The use of contact precautions for CRO-positive patients was associated with a reduced rate (7.4 vs 93.5 per 1000 patient-days at risk) and odds (aOR 0.03, 95% CrI 0.01-0.17) of CRO acquisition among susceptible patients, resulting in an estimated absolute risk reduction of 9.0% (95% CrI 7.6-9.2%). Also, carbapenem administration to susceptible patients was associated with increased odds of CRO acquisition (aOR 2.38, 95% CrI 1.70-3.29).

CONCLUSIONS AND RELEVANCE

In this population-based cohort study, the use of contact precautions for patients colonized or infected with CROs was associated with lower risk of CRO acquisition among susceptible patients, even after adjusting for antibiotic exposure. Further studies that include organism genotyping are needed to confirm these findings.

Effects of sewer biofilms on the degradability of carbapenems in wastewater using laboratory scale bioreactors

Carbapenems are last-resort antibiotics used to treat bacterial infections unsuccessfully treated by most common categories of antibiotics in humans. Most of their dosage is secreted unchanged as waste, thereby making its way into the urban water system. There are two major knowledge gaps addressed in this study to gain a better understanding of the effects of their residual concentrations on the environment and environmental microbiome: development of a UHPLC-MS/MS method of detection and quantification from raw domestic wastewater via direct injection and study of their stability in sewer environment during the transportation from domestic sewers to wastewater treatment plants. The UHPLC-MS/MS method was developed for four carbapenems: meropenem, doripenem, biapenem and ertapenem, and validation was performed in the range of 0.5-10 μg/L for all analytes, with limit of detection (LOD) and limit of quantification (LOQ) values ranging from 0.2-0.5 μg/L and 0.8-1.6 μg/L respectively. Laboratory scale rising main (RM) and gravity sewer (GS) bioreactors were employed to culture mature biofilms with real wastewater as the feed. Batch tests were conducted in RM and GS sewer bioreactors fed with carbapenem-spiked wastewater to evaluate the stability of carbapenems and compared against those in a control reactor (CTL) without sewer biofilms, over a duration of 12 h. Significantly higher degradation was observed for all carbapenems in RM and GS reactors (60 - 80%) as opposed to CTL reactor (5 - 15%), which indicates that sewer biofilms play a significant role in the degradation. First order kinetics model was applied to the concentration data along with Friedman's test and Dunn's multiple comparisons analysis to establish degradation patterns and differences in the degradation observed in sewer reactors. As per Friedman's test, there was a statistically significant difference in the degradation of carbapenems observed depending on the reactor type (p = 0.0017 - 0.0289). The results from Dunn's test indicate that the degradation in the CTL reactor was statistically different from that observed in either RM (p = 0.0033 - 0.1088) or GS (p = 0.0162 - 0.1088), with the latter two showing insignificant difference in the degradation rates observed (p = 0.2850 - 0.5930). The findings contribute to the understanding about the fate of carbapenems in urban wastewater and the potential application of wastewater-based epidemiology.

Genetic and enzymatic characterization of two novel blaNDM-36, -37 variants in Escherichia coli strains

The widespread of different NDM variants in clinical Enterobacterales isolates poses a serious public health concern, which requires continuous monitoring. In this study, three E. coli strains carrying two novel blaNDM variants of blaNDM-36, -37 were identified from a patient with refractory urinary tract infection (UTI) in China. We conducted antimicrobial susceptibility testing (AST), enzyme kinetics analysis, conjugation experiment, whole-genome sequencing (WGS), and bioinformatics analysis to characterize the blaNDM-36, -37 enzymes and their carrying strains. The blaNDM-36, -37 harboring E. coli isolates belonged to ST227, O9:H10 serotype and exhibited intermediate or resistance to all β-lactams tested except aztreonam and aztreonam/avibactam. The genes of blaNDM-36, -37 were located on a conjugative IncHI2-type plasmid. NDM-37 differed from NDM-5 by a single amino acid substitution (His261Tyr). NDM-36 differed from NDM-37 by an additional missense mutation (Ala233Val). NDM-36 had increased hydrolytic activity toward ampicillin and cefotaxime relative to NDM-37 and NDM-5, while NDM-37 and NDM-36 had lower catalytic activity toward imipenem but higher activity against meropenem in comparison to NDM-5. This is the first report of co-occurrence of two novel blaNDM variants in E. coli isolated from the same patient. The work provides insights into the enzymatic function and demonstrates the ongoing evolution of NDM enzymes.

Molecular characterisation of colistin and carbapenem-resistant clinical isolates of Acinetobacter baumannii from Southeast Europe

OBJECTIVES

To characterise 11 colistin- and carbapenem-resistant Acinetobacter baumannii isolates recently emerging in hospital settings.

METHODS

A. baumannii isolates were collected from hospitalised patients under colistin treatment in three countries of Southeast Europe: Turkey, Croatia, and Bosnia and Herzegovina. Isolates were identified using molecular methods.

RESULTS

Isolates from Turkey and Croatia belong to the sequence types ST195 or ST281 of the clone lineage 2, while the single isolate from Bosnia and Herzegovina belongs to the ST231 of clone lineage 1. All isolates turned out to be highly resistant to colistin (MIC ≥ 16 mg/L) and have point mutations in pmrCAB operon genes. The colistin-resistant isolate from Bosnia and Herzegovina had a unique P170L point mutation in the pmrB gene and the R125H point mutation in the pmrC gene. The L20S mutation in the pmrA gene was detected only in isolates from Croatia and has never been reported before in isolates from this country.

CONCLUSION

Colistin resistance in A. baumannii in hospitalised patients receiving colistin treatment is a result of chromosomal mutations. The pattern of point mutations in pmrCAB genes suggests a spread of specific colistin-resistant isolates within the hospital.

Clonal evolution and antimicrobial resistance of Acinetobacter baumannii isolates from Korean hospitals over the last decade

The wide-spread of drug-resistant Acinetobacter baumannii is a global health problem. This study investigated the clonal distribution and antimicrobial resistance of 167 A. baumannii isolates from two Korean university hospitals from 2009 to 2019 by analyzing the sequence types (STs), antimicrobial resistance, and resistance determinants of carbapenems and aminoglycosides. Twenty STs, including 16 pre-existing STs and four unassigned STs, were identified in A. baumannii isolates using the Oxford multilocus sequence typing scheme. Two STs, ST191 (n = 77) and ST451 (n = 40), were prevalent, and majority (n = 153) of the isolates belonged to clonal complex 208. The ST191 isolates were detected during the study period, whereas ST451 isolates were detected after 2016. One hundred forty-seven (87%) of 167 A. baumannii isolates were non-susceptible to carbapenems. The ST191 and ST451 isolates exhibited higher resistance to antimicrobial agents than that of the sporadic ST isolates. Interestingly, ST451 isolates exhibited lower susceptibility to minocycline and tigecycline than the other ST isolates. All carbapenem-non-susceptible A. baumannii isolates, except four, carried the ISAbaI-bla_OXA-23 structure. armA was detected in all amikacin-non-susceptible isolates (n = 128) except for one isolate. Five aminoglycoside-modifying enzyme (AME) genes were detected, but their carriage varied between STs; ant(3″)-Ia and aac(6')-Ib were more common in ST191 than in ST451, while aph(3')-Ia was more common in ST451 than in ST191. This study demonstrated the clonal evolution related to antimicrobial resistance in A. baumannii.

Outpatient parenteral antimicrobial therapy (OPAT) from an emergency model applied during the COVID-19 pandemic to standard of care: Preliminary lessons from our experience

OBJECTIVES

We wish to report on our experience of OPAT during the first two years of the COVID19 outbreak.

PATIENTS AND METHODS

We recorded data on all patients treated in the OPAT regimen in 2020 and 2021 and compared overall trends, use of carbapenems and saved days of hospitalization.

RESULTS

The OPAT model enabled us to ensure the administration of first choice antibiotic therapy to 239 patients with an increase of 21.3% from 2020 to 2021 (108 vs 131). Applying this model, we also recorded a reduction in the use of carbapenems from 33% in 2020 to 26% in 2021 and a total of 3041 recovery days saved in 2021.The clinical cure rate reached 94%. Few adverse events occurred (35/239; 14.6%), and they did not require hospitalization.

CONCLUSION

OPAT is a safe, efficacious, and cost-effective model that functioned effectively during the COVID-19 crisis and could become the standard of care for the treatment of selected patients.

Carbapenem-sparing beta-lactam/beta-lactamase inhibitors versus carbapenems for bloodstream infections caused by extended-spectrum beta-lactamase-producing Enterobacteriaceae: a systematic review and meta-analysis

OBJECTIVES

Bloodstream infections (BSIs) caused by extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-PE) have become a worldwide public health threat, and beta-lactam/beta-lactamase inhibitor combinations (BLBLIs) are considered as one reliable carbapenem-sparing antibiotic. However, it is still controversial whether BLBLIs are truly noninferior to carbapenems. Therefore, we conducted this meta-analysis to compare the efficacy of BLBLIs with carbapenems for ESBL-PE BSIs.

METHODS

A systematic search of PubMed, Cochrane Library, and Embase was conducted until December 2021 to enroll studies comparing BLBLIs with carbapenems for ESBL-PE BSIs. A subgroup analysis was performed based on the choice of therapy (empirical, definitive, and mixed therapy). The protocol was registered in the International Prospective Register of Systematic Reviews (#CRD42022316011).

RESULTS

A total of 2786 patients from one randomized clinical trial and 25 cohorts were included. There was no statistically significant difference between BLBLIs and carbapenems groups in therapeutical response (odds ratio [OR] = 1.19, P = 0.45) and mortality (OR = 1.06, P = 0.68). Furthermore, although the statistical difference was also not found in the subgroup analysis, BLBLIs performed better in definitive therapy than empirical therapy than carbapenems, with a numerically higher therapeutical response (OR = 1.42 vs 0.89) and a mildly lower mortality (OR = 0.85 vs 1.14).

CONCLUSION

BLBLIs were noninferior to carbapenems for ESBL-PE BSIs, especially in definitive therapy. BLBLIs may be a valid alternative to spare the use of carbapenems.

Correlation between antibiotic use and antibiotic resistance: A multicenter study using the Japan Surveillance for Infection Prevention and Healthcare Epidemiology (J-SIPHE) system in Hokkaido, Japan

BACKGROUND

The Japan Surveillance for Infection Prevention and Healthcare Epidemiology (J-SIPHE) system aggregates information related to antimicrobial resistance (AMR) measures in participating medical institutions nationwide and is intended to be used for promotion of AMR measures in participating facilities and their communities. This multicenter study aimed to determine the usefulness of the J-SIPHE system for evaluating the correlation between antibiotic use and antibiotic resistance in Hokkaido, Japan.

METHODS

Data on antibiotic use and detection rate of major resistant Gram-negative bacteria at 19 hospitals in 2020 were collected from the J-SIPHE system, and data correlations were analyzed using JMP Pro.

RESULTS

The detection rate of carbapenem-resistant Pseudomonas aeruginosa was significantly positively correlated with carbapenem use (Spearman's ρ = 0.551; P = .015). There were significant positive correlations between the detection rate of fluoroquinolone-resistant Escherichia coli and the use of piperacillin/tazobactam, carbapenems, and quinolones [ρ = 0.518 (P = .023), ρ = 0.76 (P < .001), and ρ = 0.502 (P = .029), respectively].

CONCLUSIONS

This is the first multicenter study to investigate the correlation between antibiotic use and antibiotic resistance using the J-SIPHE system. The results suggest that using this system may be beneficial for promoting AMR measures.

Carbapenem-Resistant enterobacterales in individuals with and without health care risk factors -Emerging infections program, United States, 2012-2015

BACKGROUND

Carbapenem-resistant Enterobacterales (CRE) are usually healthcare-associated but are also emerging in the community.

METHODS

Active, population-based surveillance was conducted to identify case-patients with cultures positive for Enterobacterales not susceptible to a carbapenem (excluding ertapenem) and resistant to all third-generation cephalosporins tested at 8 US sites from January 2012 to December 2015. Medical records were used to classify cases as health care-associated, or as community-associated (CA) if a patient had no known health care risk factors and a culture was collected <3 days after hospital admission. Enterobacterales isolates from selected cases were submitted to CDC for whole genome sequencing.

RESULTS

We identified 1499 CRE cases in 1194 case-patients; 149 cases (10%) in 139 case-patients were CA. The incidence of CRE cases per 100,000 population was 2.96 (95% CI: 2.81, 3.11) overall and 0.29 (95% CI: 0.25, 0.35) for CA-CRE. Most CA-CRE cases were in White persons (73%), females (84%) and identified from urine cultures (98%). Among the 12 sequenced CA-CRE isolates, 5 (42%) harbored a carbapenemase gene.

CONCLUSIONS

Ten percent of CRE cases were CA; some isolates from CA-CRE cases harbored carbapenemase genes. Continued CRE surveillance in the community is critical to monitor emergence outside of traditional health care settings.

Phenotypic and genotypic detection of resistance mechanisms in carbapenem-resistant gram-negative bacteria isolated from Egyptian ICU patients with first emergence of NDM-1 producing Klebsiella oxytoca

Background and Objectives

Carbapenems are considered the last resort to treat several infections, particularly in intensive care units (ICUs). However, increasing carbapenem resistance is problematic because it leads to high morbidity and mortality rates. This study aimed to determine the rate of carbapenem resistance among Gram-negative bacteria collected from patients in ICUs and to identify their resistance mechanisms using phenotypic and genotypic methods.

Materials and Methods

Antimicrobial susceptibility testing was carried out using the disc diffusion method among 180 Gram-negative bacterial isolates. Productions of carbapenemases, metallo-beta-lactamases (MBLs) and the harboring of carbapenemase-encoding genes, were detected in 40 selected carbapenem-resistant Gram-negative bacteria (CR-GNB).

Results

Of 40 selected CR-GNB isolates, 28 (70%), and 20 (50%) isolates were phenotypically positive for carbapenemase, and MBL production, respectively. Furthermore, 22 (55%) showed amplification of one or more of the carbapenemase-encoding genes, including bla _NDM-1, bla _VIM-2, and bla _OXA-48. This study described the first emergence of NDM-1 producing Klebsiella oxytoca in Egyptian ICUs.

Conclusion

High incidence of CR-GNB detected in the ICUs in our study area may be attributed to the overuse of antibiotics, including carbapenems, and improper application of infection control measures. These findings confirm the need for the application of a strict antibiotic stewardship program.

Prevalence of main quinolones and carbapenems resistance genes in clinical and veterinary Escherichia coli strains

Background and Objectives

Antibiotics-resistant Escherichia coli strains are considered one of the most important causes of human and animal infections worldwide. The aim of current study was to detect common resistance (carbapenems and quinolones) genes by PCR.

Materials and Methods

A total of 100 E. coli strains isolated from human urinary tract infection and 20 isolated strains of aborted sheep embryos were collected. PCR was performed using specific primers to detect the resistance genes.

Results

Overall, among the quinolones resistance genes, qnrS resistance gene had the highest frequency (48%) and among carbapenem resistance genes, imp resistance gene had the highest frequency (45%). The frequency of resistance genes, IMP (28.45%), KPC (9.5%), VIM (9.15%), NDM (7.20%) were observed in clinical and veterinary strains, respectively. According to the results, 38.6% of E. coli strains had at least one from five genes of resistance to quinolones. The lowest frequency of resistance gene was related to qnrA, which was observed in only 29 (24.2%) strains.

Conclusion

Monitoring of carbapenem and quinolone resistance in pathogenic E. coli to humans and animals has an important value in revising treatment guidelines and the national public health, and plays an important role in preventing the spread of resistant strains.

The threat of carbapenem resistance in Eastern Europe in patients with decompensated cirrhosis admitted to intensive care unit

BACKGROUND

Multidrug-resistant organisms are an increasing concern in patients with decompensated cirrhosis.

AIM

We aimed to evaluate the prevalence of infections with carbapenem-resistant Enterobacteriaceae in patients with decompensated cirrhosis.

METHODS

Patients with decompensated cirrhosis admitted to ICU were included. The isolated Enterobacteriaceae strains were tested for carbapenemase-producing genes using the Roche LightMix® Modular VIM/IMP/NDM/GES/KPC/OXA48-carbapenemase detection kit.

RESULTS

48 culture-positive infections were registered in 75 patients with acutely decompensated cirrhosis. Thirty patients contracted a second infection. 46% of bacteria isolated at admission and 60% of bacteria responsible for infections identified during ICU-stay were multiresistant. ESBL+ Enterobacteriaceae were predominant at admission, while carbapenem-resistance was dominant in both Enterobacteriaceae and Non-Fermenting-Gram-Negative Bacteria responsible for infections diagnosed during hospitalisation. OXA 48 or KPC type carbapenemases were present in 30% of the analyzed Enterobacteriaceae and in 40% of the phenotypically carbapenem-resistant Klebsiella pneumoniae strains. The length of ICU stay was a risk-factor for a second infection (p=0.04). Previous carbapenem usage was associated with occurence of infections with carbapenem-resistant Gram-negative bacteria during hospitalization (p=0.03).

CONCLUSION

The prevalence of infections with carbapenem-resistant Enterobacteriaceae is high in patients with decompensated cirrhosis admitted to ICU. Carbapenemase-producing genes in Enterobacteriaceae in our center are bla_OXA-48 and bla_KPC.

Recurrent emergence of Klebsiella pneumoniae carbapenem resistance mediated by an inhibitory ompK36 mRNA secondary structure

Outer membrane porins in Gram-negative bacteria facilitate antibiotic influx. In Klebsiella pneumoniae, modifications in the porin OmpK36 are implicated in increasing resistance to carbapenems. An analysis of large K. pneumoniae genome collections, encompassing major healthcare-associated clones, revealed the recurrent emergence of a synonymous cytosine-to-thymine transition at position 25 (25c > t) in ompK36. We show that the 25c > t transition increases carbapenem resistance through depletion of OmpK36 from the outer membrane. The mutation attenuates K. pneumoniae in a murine pneumonia model, which accounts for its limited clonal expansion observed by phylogenetic analysis. However, in the context of carbapenem treatment, the 25c > t transition tips the balance toward treatment failure, thus accounting for its recurrent emergence. Mechanistically, the 25c > t transition mediates an intramolecular messenger RNA (mRNA) interaction between a uracil encoded by 25t and the first adenine within the Shine-Dalgarno sequence. This specific interaction leads to the formation of an RNA stem structure, which obscures the ribosomal binding site thus disrupting translation. While mutations reducing OmpK36 expression via transcriptional silencing are known, we uniquely demonstrate the repeated selection of a synonymous ompK36 mutation mediating translational suppression in response to antibiotic pressure.

Hybrid IncFIA/FIB/FIC(FII) plasmid co-carrying blaNDM-5 and fosA3 from an Escherichia coli ST117 strain of retail chicken

Carbapenems and fosfomycin are important antibiotics used to treat Enterobacteriaceae-associated infections. This study aimed to characterize the co-resistance and co-dissemination mechanism of carbapenem and fosfomycin resistance in an Escherichia coli ST117 strain isolated from retail chicken meat. Antimicrobial susceptibility testing showed that an E. coli CS18F strain had a multidrug resistance profile, including carbapenem and fosfomycin resistance. The presence of bla_NDM-5 and fosA3 genes was confirmed by PCR and Sanger sequencing. The bla_NDM-5 and fosA3 genes were successfully transferred to the recipient strain E. coli J53 via conjugation, and the transconjugants had elevated minimum inhibitory concentrations (MICs) for meropenem and fosfomycin. Whole genome sequencing (WGS) of E. coli CS18F revealed that bla_NDM-5 and fosA3 were colocalized on an IncFIA/FIB/FIC(FII) type plasmid of 189,141 bp, which was designated as pCS18F-NDM-Fos. A novel structure with five IS26 sequences flanking the multiple drug resistance region (MDRR) was identified, and three copies of IS26 were found to be flanked bla_NDM-5, fosA3, dfrA12, aadA2, and sul1. Three types of translocation units (TUs) were identified by PCR, containing either the resistance gene bla_NDM-5 and an IS26 sequence, fosA3, and an IS26 sequence, or both, indicating their potential co-transfer via TUs. Thus, this is an unprecedented report of the presence of a plasmid co-carrying bla_NDM-5 and fosA3 and TUs potentially mediating their simultaneous transfer.

Criteria Restricting Inappropriate Meropenem Empiricism (CRIME): a quasi-experimental carbapenem restriction pilot at a large academic medical centre

The broad-spectrum activity of carbapenems makes them appealing for empirical use; however, they are associated with development of Clostridioides difficile infection (CDI) and multidrug resistance. Selective carbapenem use is vital in maintaining their effectiveness. We examined the impact of meropenem restriction criteria on utilisation and patient outcomes. This quasi-experimental study was conducted at a single academic medical centre after medication use evaluation found frequent inappropriate meropenem utilisation. Antimicrobial stewardship-led restriction criteria were developed and implemented in February 2022. Investigators aimed to determine how restriction criteria affected meropenem utilisation across 8 weeks in the pre- (February-April 2020) versus post-implementation period (February-April 2022). The primary outcome was inappropriateness of meropenem utilisation. Secondary outcomes included days of therapy per 1000 patient-days (DOT/1000 PD), hospital length of stay (LOS), CDI Standardized Infection Ratio (SIR), and acquisition cost. Across the 8-week timeframes, reductions in inappropriate meropenem use (64.5% vs. 12.8%; P < 0.001), duration of therapy [5.8 (3.2-7.3) vs. 2.4 (1.0-5.5) days; P < 0.001] and utilisation (30.5 vs. 8.3 DOT/1000 PD; P < 0.001) pre- versus post-implementation were observed. Total meropenem orders decreased by 65% (P < 0.001). Median hospital LOS also decreased between periods [11.9 (7.8-20.4) vs. 9.2 (5.4-15.2) days], although not statistically significant (P = 0.051). There was no difference in CDI SIR (0.1 vs. 0.1; P = 0.99). Projected annual cost savings were ∼US$57 300. Implementation of antimicrobial stewardship-initiated restriction criteria can reduce inappropriate meropenem utilisation, overall number of orders, and total duration of therapy.

Rapid identification of polypeptide from carbapenem-resistant and susceptible Escherichia coli via Orbitrap-MS and pattern recognition analyses

A rapid and accurate analytical method was established to identify CREC and CSEC. Orbitrap-MS was used to detect the polypeptide of CREC and CSEC strains, and MS data were analyzed by pattern recognition analyses such as hierarchical cluster analysis (HCA), principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA), and orthogonal partial least squares discriminant analysis (OPLS-DA). HCA based on the farthest distance method could well distinguish the two types of E. coli, and the cophenetic correlation coefficient of the farthest distance method was 0.901. Comparing the results of PCA, PLS-DA, and OPLS-DA, OPLS-DA exhibited the highest accuracy in predicting the CREC and CSEC strains. A total of 26 compounds were identified, and six of the compounds were the highly significant difference between the two types of strains. MS combined with pattern recognition can achieve a more comprehensive and efficient statistical analysis of complex biological samples.

First report of SPM metallo-β-lactamases producing Acinetobacter baumannii isolates in Morocco

Background and Objectives

Carbapenem-resistant Acinetobacter baumannii has recently been identified by the World Health Organization as a critical pathogen. We propose to characterize the molecular characteristics of clinical isolates of A. baumannii resistant to carbapenems collected in a Moroccan hospital.

Materials and Methods

Seventy carbapenem-resistant A. baumannii isolates from various samples were received at the microbiology laboratory of the Hospital Center. Antibiotic susceptibility was tested by the diffusion disc method and molecular characterization of antimicrobial resistance was performed by PCR and sequencing.

Results

Carbapenemase genes were detected in our isolates: the OXA-51 gene and the ISbA1 sequence were detected in all isolates (100%), the OXA-23 and OXA-58 genes were detected in 82.85% and 10% of isolates respectively, MBL genes were dominated by VIM 39 isolates (55.7%), followed by GIM 26 isolates (37%), SIM 20 isolates (28.5%), IMP 8 isolates (11, 4%), NDM 3 isolates (4%) and for the first time in Morocco SPM with 4 isolates (5.7%).

Conclusion

The emergence of resistance of A. baumannii to carbapenems is a serious problem in our hospital which requires the establishment of a prevention strategy and strict respect for hygiene to minimize their dissemination.

Carbapenems consumption and Klebsiella resistance in intensive care units in Egypt: A study to evaluate the effect of an antimicrobial stewardship program

Background

The high prevalence of carbapenem-resistant Klebsiella imposes optimizing antibiotic consumption. We aimed to evaluate the impact of antibiotic stewardship program on carbapenem consumption and the Klebsiella resistance.

Method

We retrospectively evaluated critically ill patients with isolated Klebsiella species from Elaraby hospital, Egypt during the period from April 2017 to January 2019. We collected data related to carbapenems consumption and Klebsiella clinical isolates with their antimicrobial susceptibility. Based on susceptibility, Klebsiella isolates were classified into sensitive, extended spectrum beta-lactamase (ESBL) producer, and carbapenem-resistant Klebsiella (CRK), respectively. Our primary outcome was the change in carbapenems consumption after implementing the program, while the secondary outcomes were the changes in the incidence of CRK.

Results

The study included 205 patients with isolated Klebsiella species during the study period. The antibiotic stewardship program started in March 2018. Out of the 205 patients, 61 patients (29.8%) represented the pre-intervention sample, and 144 patients (70.2%) represented the post-intervention sample. Applying the antibiotic stewardship program was associated with a significant decrease in the carbapenems consumption from 38.9 to 26.6 defined daily dose/1000 patient-days (p = 0.02). The incidence of CRK was decreased from 85.25% of total Klebsiella isolates to 48.6% (p < 0.001). Klebsiella species were more likely to be in a lower category of resistance after applying the program with an odds ratio of 6.3 (2.88-13.73) using ordinal logistic regression.

Conclusion

Applying the antibiotic stewardship program could reduce the unnecessary carbapenems use in the ICU with a subsequent decrease in the emergence of the Klebsiella-resistant strains.

Carbapenem resistance in Bacteroides fragilis: A review of molecular mechanisms

Carbapenems are an applicable subclass of β-lactam drugs in the antibiotic therapy of anaerobic infections, especially for poly-microbial cases, due to their broad antimicrobial spectrum on aerobic and anaerobic bacteria. Bacteroides fragilis is the most commonly recovered anaerobic bacteria in the clinical laboratories from mono- and poly-microbial infections. B. fragilis is relatively non-susceptible to different antibiotics, including β-lactams, tetracyclines, fluoroquinolones, and macrolides. Carbapenems are among the most effective drugs against B. fragilis strains with high-level resistance to different antibiotics. Increased antibiotic resistance of B. fragilis strains has been reported following the overuse of an antimicrobial agent. Earlier contact with carbapenems is linked with increased resistance to them that limits the options for treatment of B. fragilis caused infections, especially in cases caused by multidrug-resistant strains. Several molecular mechanisms of resistance to carbapenems have been described for different carbapenem-resistant bacteria. Understanding the mechanisms of resistance to antimicrobial agents is necessary for selecting alternative antimicrobial agents and the application of control strategies. In the present study, we reviewed the mechanisms contributing to resistance to carbapenems in B. fragilis strains.

High mortality from carbapenem-resistant Klebsiella pneumoniae bloodstream infection

In this study, it was evaluated clinical data of 107 patients with bloodstream infection (BSI) by Klebsiella pneumoniae and performed phenotypic and molecular analyzes in 50.5% (54/107) of the samples, those that showed a resistance profile to carbapenemics. The bla_KPC gene was present in 90.4% (49/54) of the samples, bla_NDM gene in one sample and, in 7.4% (4/54) of the samples, no carbapenemase gene was found. In the similarity analysis, it was found 4 main clones and 11 samples were not genetically related. The median age of the patients was 58 (40-70) years old and 60.7% (65/107) were male. When comparing two groups of patients with BSI due to K. pneumoniae with and without resistance to carbapenems, the variables ICU permanence, renal failure (IR), previous use of antimicrobials, Charlson's comorbidity index (ICCi), some invasive procedures and death showed a statistically significant difference (p < 0.05). And when relating death as a dependent variable, IR, liver failure and patients with BSI XDR or PDR, were predictors of increased mortality. Our study showed a higher mortality rate in patients with BSI due to carbapenem-resistant pneumonia with additional resistance or not to polymyxins.

Evaluation of a carbapenem antimicrobial stewardship program and clinical outcomes in a Japanese hospital

INTRODUCTION

Microorganisms can evolve and become resistant to antimicrobials, and this is known as antimicrobial resistance (AMR). Inappropriate use of antibiotics contributes to AMR, and antimicrobial stewardship programs have been developed to mitigate AMR. The Appropriate Use of Carbapenems Program was implemented in March 2019 in a university hospital and its effect was evaluated.

METHODS

We conducted a prospective audit and feedback on carbapenems at the time of prescription daily. Additionally, we compared a monthly survey of the total days of therapy (DOTs) per 1000 patient-days for carbapenems, piperacillin/tazobactam, and fluoroquinolones. The susceptibility of Pseudomonas aeruginosa to meropenem, piperacillin/tazobactam, and levofloxacin was tested before (January 2018 to February 2019) and after (March 2019 to December 2020) the intervention.

RESULTS

The monthly median DOTs of carbapenem usage decreased after the intervention; carbapenem use immediately declined during the intervention period. The monthly median DOTs of piperacillin/tazobactam and fluoroquinolones also decreased and continued to decline significantly after the intervention. Susceptibility of P. aeruginosa to meropenem, piperacillin/tazobactam, and levofloxacin did not change significantly during the study.

CONCLUSION

The implementation of the Appropriate Use of Carbapenems Program was effective in reducing the use of broad-spectrum antibiotics and maintaining the antibiotic susceptibility of P. aeruginosa.

A retrospective molecular epidemiological scenario of carbapenemase-producing Klebsiella pneumoniae clinical isolates in a Sicilian transplantation hospital shows a swift polyclonal divergence among sequence types, resistome and virulome

In this work, we assessed and characterized the epidemiological scenario of carbapenem-resistant Klebsiella pneumoniae strains (CR-Kp) at IRCCS-ISMETT, a transplantation hospital in Palermo, Italy, from 2008 to 2017. A total of 288 K. pneumoniae clinical isolates were selected based on their resistance to carbapenems. Molecular characterization was also done in terms of the presence of virulence and resistance genes. All patients were inpatients from our facility and clinical isolates were collected from several sources, either from infection or colonization cases. We observed that, in agreement with the Italian epidemiological scenario, initially only ST258 and ST512 clade II (but not from clade I) were identified from 2008 to 2011. From 2012 onwards, other STs have been observed, including the clinically relevant ST101 and ST307, but also others not previously observed in other Italian health settings, such as ST220 and ST753. The presence of genes involved in resistance and virulence was confirmed, and a heterogeneous genetic resistance profile throughout the years was observed. Our work highlights that resistance genes are rapidly disseminating between different and novel K. pneumoniae clones which, combined with resistance to multiple antibiotics, can derive into more aggressive and pathogenic multidrug-resistant strains of clinical importance. Our results stress the importance of continuous surveillance of CR Enterobacterales in health facilities so that novel STs carrying resistance and virulence genes that may become increasingly pathogenic can be identified and adequate therapies to adopted to avoid their dissemination and derived pathologies.

Rapid increase in occurrence of carbapenem-resistant Enterobacteriaceae in healthy rural residents in Shandong province, China, from 2015 to 2017

OBJECTIVES

The global increase of carbapenem-resistant Enterobacteriaceae (CRE) is a growing concern. Infections caused by CRE are associated with increased mortality and length of hospital stay, emphasizing the health and economic burden posed by these pathogens. Although CRE can inhabit the human gut asymptomatically, colonization with CRE is associated with increased risk of CRE infection and mortality. In this study, we investigated the occurrence and characteristics of CRE in fecal samples from healthy persons in 12 villages in Shandong, China.

METHODS

Screening for CRE in fecal samples was performed by selective cultivation. MICs of meropenem were determined with the agar dilution method. Multilocus sequence type (MLST) and carbapenemase gene carriage of the isolates were determined with whole-genome sequencing. Genetic relatedness of E. coli isolates was determined by core genome MLST.

RESULTS

CRE carriage increased from 2.4% to 13% from 2015 to 2017. Most CRE isolates (93%) were E. coli and all carried NDM-type carbapenemases. The STs among the E. coli were diverse. The single most common was the highly epidemic strain ST167, which was only observed among isolates from 2017.

CONCLUSION

We report a rapid increase in occurrence of CRE from 2.4% to 13% among fecal samples collected from healthy rural residents of Shandong province, China, from 2015 to 2017. Colonization with CRE is known to increase the risk of CRE infection and the worrying deterioration of the epidemiological situation in the region reported here indicate a need for further monitoring and possible interventions.

Pharmacist-led quality control circle in sustained reduction of carbapenem-resistance at a Chinese tertiary teaching hospital

BACKGROUND

The spread of carbapenem-resistant Gram-negative bacteria poses a substantial threat to morbidity and mortality worldwide, which is mainly attributed to the overuse of carbapenem. This study aimed to evaluate the use of a quality control circle (QCC) in controlling the overuse of carbapenems and improving the state of carbapenem resistance at a Chinese tertiary teaching hospital.

METHODS

A pharmacist-led multidisciplinary QCC project was carried out and the plan-do-check-act (PDCA) method was applied for 12 months. The data on carbapenem consumption, bacterial identification, and antibacterial susceptibility testing were collected to evaluate the effect of this project.

RESULTS

The antibiotics use density (AUD) of carbapenems exhibited a decreasing trend over time (P<0.001), and the AUD of meropenem, imipenem, and biapenem decreased by 30.20%, 42.45%, and 78.05% after the intervention, respectively. The total AUD of carbapenems decreased from 7.37 to 3.96, which included the decrease in the irrational use of carbapenems by 1.61, accounting for 47.21% of the total. Moreover, the positive correlations were discovered between the resistance rate of carbapenem-resistant Klebsiella pneumonia (CRKP)/Acinetobacter baumannii (CRAB) and the AUD of carbapenems (P<0.05). The resistance rate of CRKP and CRAB decreased from 51.93% and 89.21% to 32.94% and 60.66%, respectively, following QCC project implementation.

CONCLUSIONS

This is the first study to highlight the success of a multifaceted intervention QCC project and PDCA method, which led to a significant reduction in the AUD and resistance rate of carbapenems. QCC is a feasible and effective management tool for improving the quality of carbapenem use in medical institutions.

Trend analysis of carbapenem-resistant Gram-negative bacteria and antimicrobial consumption in the post-COVID-19 era: an extra challenge for healthcare institutions

The incidence density trend of the carbapenem-resistant Gram-negative bacteria was analysed in device-associated infections and antimicrobial consumption in 99 critical care facilities in a low/middle-income country, between January 2019 and December 2020. Carbapenem-resistant Acinetobacter baumannii (CRAB) per 1000 patient-days increased in 2020 and this finding had a strong positive correlation with the incidence density of COVID-19 by the Spearman test. Polymyxin consumption also increased in 2020 but without significant correlation with CRAB or COVID-19 incidence density, presumably due to empirical and untargeted prescribing as a consequence of concern about CRAB infections. These findings are a warning to infection control programmes and antimicrobial stewardship.

A comparison of the antimicrobial resistance of fecal Bacteroides isolates and assessment of the composition of the intestinal microbiotas of carbapenem-treated and non-treated persons from Belgium and Hungary

The antimicrobial susceptibilities of Bacteroides strains isolated from the feces of imipenem-treated patients from Belgium and Hungary were compared with those isolated from the normal microbiota from these two and five other European countries and assessed. Of the 10 antibiotics tested, highly significant differences were found with cefoxitin (decrease for Belgium and for this two and the five countries from the previous study), clindamycin (decrease for Belgium and for this two and the five countries from the previous study) and moxifloxacin (increase for Belgium and for this two and the five countries from the previous study) relative to normal microbiota strains reported earlier. Imipenem treatment brought about modest, but notable differences in the compositions of the microbiomes where there was less diversity in the treated group relative to the non-treated group.

Carbapenem stewardship program in a French university children's hospital

INTRODUCTION

Carbapenems, last-resort antibiotics, are widely used as first-line treatment in patients carrying extended-spectrum beta-lactamases (ESBL) Enterobacteriaceae, including in a pediatric setting. We aimed to implement an antibiotic stewardship program (ASP) to improve the use of carbapenems.

METHODS

We implemented an ASP at the Bordeaux Children's University Hospital with 6-month audits on prescribing practice before and after an intervention (revision of antibiotic treatment protocols, a half-day educational session with feedback of the first study period). The number of carbapenem prescriptions was analyzed and two criteria were used to assess conformity of the indication for carbapenem prescription and conformity of the reassessment. A logistic regression was used to assess the overall compliance of carbapenem prescriptions over the two periods adjusted for ESBL carriage.

RESULTS

A total of 57 patients were included with 37 carbapenem prescriptions before the intervention and 23 after. Overall carbapenem consumption decreased from 0.54 prescriptions per 100 admissions to 0.32 (p = 0.06). Conformity increased during the study for indication (46-87%, p = 0.004) and for reassessment (48-78%, p = 0.04) and was significantly associated with the second study period, after adjustment for ESBL carriage.

CONCLUSION

Our intervention contributed to a significant improvement in the compliance to indications for carbapenem indication and in the reassessment of the prescription.

UVC-induced degradation of cilastatin in natural water and treated wastewater

This work reports for the first time the UVC photodegradation of cilastatin, a renal dehydropeptidase inhibitor co-adminstered with the imipenem antibiotic. Initially, solutions of cilastatin at varying concentrations were prepared in ultra-pure water and the direct photolysis of cilastatin was monitored under 254-nm irradiation. Degradation was slower at higher initial cilastatin concentrations, due to absorption saturation. Of the different eluting photoproducts, only one was tentatively identified as oxidized cilastatin bearing a sulfoxide group. UV-254 photolysis occurred faster at lower pH values, because the protonated forms of the molecule (H₃A⁺, H₂A) have both higher absorption coefficients and higher photolysis quantum yields than the non-protonated ones (HA^-, A^2-). The direct photolysis of cilastatin does not involve ^•OH, as excluded by experiments in which t-butanol was added as ^•OH scavenger, whereas the presence of humic acids inhibited photolysis due to competition for radiation absorption. The same explanation partially accounts for the observation that the photolysis kinetics of cilastatin was slower in tap water, river water and treated wastewater samples compared to ultra-pure water. Moreover, the direct photolysis quantum yield was also lower in water matrices compared to ultra-pure water. Similar findings reported for triclosan and the herbicide 2-methyl-4-chlorophenoxyacetic acid in previous studies might suggest that the water matrix components could carry out either physical quenching of cilastatin's excited states or back-reduction to cilastatin of the partially oxidized degradation intermediates. Overall, the present results demonstrate that UVC irradiation is a fast and efficient process for the degradation of cilastatin in natural water and treated wastewater.

High prevalence of multidrug-resistant non-fermentative Gram-negative bacilli harboring bla IMP-1 and bla VIM-1 metallo-beta-lactamase genes in Birjand, south-east Iran

Background and Objectives:

Non-fermentative Gram-negative Bacilli (NFGNB) is known as a major cause of healthcare-associated infections with high levels of antibiotic resistance. The aim of this study was to investigate the antibiotic resistance profiles and molecular characteristics of metallo-beta-lactamase (MBL)-producing NFGNB.

Materials and Methods:

In this cross-sectional study, the antibiotic resistance profile of 122 clinical NFGNB isolates was determined by the Kirby-Bauer disk diffusion and microdilution broth methods. Bacterial isolates were investigated for the detection of MBLs production using the combination disk diffusion Test (CDDT). The existence of bla_IMP, bla_VIM, and bla_NDM genes in all carbapenem-resistant isolates was determined employing polymerase chain reaction (PCR) assays.

Results:

High resistance in Pseudomonas aeruginosa was reported to cefotaxime and minocycline, whereas Acinetobacter baumannii isolates were highly resistant to all antibiotics except colistin. Multidrug resistance (MDR)-NFGNB (66% vs. 12.5%, P=0.0004) and extensively drug resistant (XDR)-NFGNB (55.7% vs. 12.5%, P=0.001) isolates were significantly more common in hospitalized patients than in outpatients. The production of MBL was seen in 40% of P. aeruginosa and 93.3% of A. baumannii isolates. It was found that 33.3% and 46.7% of carbapenem-resistant P. aeruginosa isolates, and 13.3% and 28.9% of carbapenem-resistant A. baumannii isolates were harboring bla_IMP-1 and bla_VIM-1 genes, respectively. The incidence of MDR (98.2% vs. 28.3%, P<0.001) and XDR (96.4% vs. 11.7%, P<0.001) in MBL-producing NFGNB isolates was significantly higher than non-MBL-producing isolates.

Conclusion:

This study demonstrated a higher rate of resistance among NFGNB isolates with an additional burden of MBL production within them, warranting a need for robust microbiological surveillance and accurate detection of MBL producers among the NFGNB.

Prevalence of multidrug-resistance and bla VIM and bla IMP genes among gram-negative clinical isolates in tertiary care hospital, Kathmandu, Nepal

Background and Objectives

Carbapenems have been the choice of antibiotics for the treatment of infections caused by multidrug-resistant bacteria. The main objective of this study was to determine the prevalence of carbapenemase (bla _VIM and bla _IMP ) producing isolates among Enterobacteriaceae, Pseudomonas aeruginosa, and Acinetobacter baumannii.

Materials and Methods

A total of 1,151 clinical samples were collected from the patients visiting Annapurna Neurological Institute and Allied Science and Annapurna Research Centre, Kathmandu, between June 2017 and January 2018. Antibiotic susceptibility testing (AST) was performed on the Enterobacteriaceae, P. aeruginosa and A. baumannii isolates using the Kirby-Bauer disk diffusion method. The modified Hodge test (MHT) was performed on the carbapenem-resistant isolates to confirm carbapenemase production. DNA was extracted and then screened for bla _VIM and bla _IMP genes by multiplex PCR.

Results

Of the total 1,151 clinical samples, 253 (22.0%) showed positive growth. Of them, 226 (89.3%) were identified as Enterobacteriaceae, P. aeruginosa, and A. baumannii. Among the 226 isolates, 106 (46.9%) were multidrug-resistant. Out of the 106, 97 (91.5%) isolates showed resistance to at least one of the carbapenem used. Among the 97 carbapenem-resistant isolates, 67 (69.1%) showed the modified Hodge test (MHT) positive results. bla _VIM and bla _IMP were detected in 40 and 38 isolates respectively using multiplex PCR assay.

Conclusion

This study determined a high prevalence of MDR and carbapenem resistance among Enterobacteriaceae, P. aeruginosa, and A. baumannii as detected by the presence of bla _VIM and bla _IMP genes. This study recommends the use of rapid and advanced diagnostic tools along with conventional phenotypic detection methods in the clinical settings for early detection and management of drug-resistant pathogens to improve treatment strategies.

Carbapenem resistance in Acinetobacter baumannii clinical isolates from northwest Iran: high prevalence of OXA genes in sync

Background and Objectives

Carbapenem treatment for Acinetobacter baumannii infections presently faces threats owing to the production of several types of carbapenemase enzymes, prevalence of which varies among different countries. We explored the current trend of antibiotic resistance in A. baumannii clinical isolates from North West Iran, sought the mechanism of carbapenem resistance and addressed the sequence type groups in carbapenem resistant A. baumannii (CRAB).

Materials and Methods

A. baumannii (n=112) isolates were recovered from various clinical specimens of patients admitted in internal, surgery, burn, infectious diseases and various ICUs wards. Genetically confirmed A. baumannii isolates were screened for carbapenem resistance by the Kirby-Bauer and E-test and the presence of bla _MBL, bla _OXA-like, ISAba1 genes by PCR. Sequence groups were identified by multiplex PCR.

Results

Multidrug-resistance (MDR) was a characteristic feature of all A. baumannii isolates. Frequency of oxacillinase genes in combination including bla _OXA-51-like/bla _OXA-23-like, bla _OXA-51-like/bla_{OXA-24/40-like}and bla _OXA-51-like/bla _OXA-23-like/bla _{OXA-24/40-like} was 82.1%, 36.6% and 25.8% respectively. Blending of oxacillinase and MBL genes was evident in eight bla _OXA-23-like positive and 7 bla _OXA-24-like positive isolates thereby depicting synchronous etiology of carbapenem resistance. Amongst CRAB isolates, 97.3% contained ISAba1 element and 50.9% belonged to the European clone II.

Conclusion

Synchronicity among bla _OXA-like with bla _MBL and ISAba1 gene was a hallmark of this investigation. Though origin or route of transmission was not elucidated in this study but co-existence among OXA and MBL producing genes is a therapeutic concern demanding strict surveillance strategies and control programs to halt the dissemination of these isolates in the hospital setting.

Successful treatment of hypervirulent Klebsiella pneumoniae bacteremia with combination carbapenem and rifampicin

Hypervirulent Klebsiella pneumoniae (hvKP) with a high mucus phenotype, can cause liver abscess and extrahepatic invasive infection. The morbidity of hvKP infections has increased recently. Here we describe a case report of septicemia caused by hvKP due to the term septic arthritis of right knee joint in a 29-year-old male. The patient was persistent fever with a peak temperature at 40.6 °C. However, based on the drug sensitivity, the treatment failed frequently. The patient did not improve clinically on susceptible monotherapy antimicrobial. Combination therapy with meropenem and rifampicin (RFP) lead to clinical improvement and discharge.

Comparison of therapy with β-lactam/β-lactamase inhibitor combinations or carbapenems for bacteraemia of nonurinary source caused by ESBL-producing Escherichia coli or Klebsiella pneumoniae

Background

Extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae has become a public health concern. This study aimed to compare the clinical outcomes of patients with nonurinary source bacteraemia caused by ESBL-producing Escherichia coli (E. coli) or Klebsiella pneumoniae (ESBL-producing EK) receiving β-lactam/β-lactamase inhibitor combinations (BLICs) versus carbapenem treatment and assess the risk factors of mortality with these two drugs.

Methods

We conducted a retrospective single-centre study of adult hospitalised patients with ESBL-producing EK bloodstream infection (BSI) from nonurinary source at our centre over a 4-year period. One hundred and eighty patients who received BLICs or carbapenems were included in the analysis. The outcome variables were 14-day treatment failure and 30-day mortality. For more reliable results, propensity score analysis was performed to compare the efficacy of the two drugs and analyse their risk factors for 30-day mortality.

Results

Out of 180 patients, 114 received BLICs, and 66 received carbapenem therapy. Compared to carbapenem-treated patients, those treated with BLICs were older and had higher age-adjusted Charlson comorbidity index, but they had shorter stay in the hospital. Additionally, their Pitt bacteraemia score, SOFA score, rate of leukaemia, and immune compromise were lower. After propensity score matching (PSM), the baseline characteristics of patients in the two treatment groups were balanced. BLICs were associated with a higher 14-day treatment failure rate (20.6%, 13/63) than carbapenems (16.3%, 7/43), although the difference was not significant in either univariate analysis (P = 0.429) or multivariate analysis (P = 0.122). And the 30-day mortality rate in BTG (11.1%, 7/63) and CTG (11.6%, 5/43) did not significantly differ (univariate analysis, P = 0.926; multivariate analysis, P = 0.420). In the multivariate analysis, after PSM, leukaemia was the only independent predictor of mortality in both BTG and CTG.

Conclusions

Our study showed that BLICs had higher 14-day treatment failure rate compared with carbapenems, although there were no statistically significant differences because of the small number of patients, therefore, further evaluation of the efficacy of BLICs is needed.