Nationwide surveillance in Thailand revealed genotype-dependent dissemination of carbapenem-resistant Enterobacterales

Clinical risk factors and outcomes of carbapenem-resistant Escherichia coli nosocomial infections in a Chinese teaching hospital: a retrospective study from 2013 to 2020

The emergence of carbapenem-resistant Escherichia coli strains poses a considerable challenge to global public health, and little is known about carbapenemase-producing E. coli strains in Tianjin, China. This study aimed to investigate the risk factors for infections with carbapenem-resistant E. coli (CREC) strains. This retrospective case-control study was conducted at a tertiary teaching hospital. A total of 134 CREC clinical isolates were collected from the General Hospital of Tianjin Medical University between 2013 and 2020. The control group was selected at a ratio of 1:1 from patients with nosocomial carbapenem-susceptible E. coli infection. Risk factors for nosocomial CREC infection and clinical outcomes were analyzed using univariate and multivariate analyses. Multivariate analysis revealed that cephalosporin exposure (odd ratio OR = 2.01), carbapenem exposure (OR = 1.96), glucocorticoid exposure (OR = 32.45), and surgical history (OR = 3.26) were independent risk factors for CREC infection. The in-hospital mortality rate in the CREC group was 29.1%, and age >65 years (OR = 3.19), carbapenem exposure (OR = 3.54), and central venous catheter insertion (OR = 4.19) were independent risk factors for in-hospital mortality in patients with CREC infections. Several factors were identified in the development of nosocomial CREC infections. The CREC isolates were resistant to most antibiotics. Reducing CREC mortality requires a comprehensive consideration of appropriate antibiotic use, underlying diseases, and invasive procedures.IMPORTANCEEscherichia coli is an opportunistic pathogen that causes severe hospital-acquired infections. The spread of carbapenem-resistant E. coli is a global threat to public health, and only a few antibiotics are effective against these infections. Consequently, these infections are usually associated with poor prognosis and high mortality. Therefore, understanding the risk factors associated with the causes and outcomes of these infections is crucial to reduce their incidence and initiate appropriate therapies. In our study, several factors were found to be involved in nosocomial carbapenem-resistant E. coli (CREC) infections, and CREC isolates were resistant to most antibiotics. Reducing CREC mortality needs a comprehensive consideration of whether antibiotics are used appropriately, underlying diseases, and invasive interventions. These findings provide valuable evidence for the development of anti-infective therapy, infection prevention, and control of CREC-positive infections.

Occurrence and mechanisms of tigecycline resistance in carbapenem- and colistin-resistant Klebsiella pneumoniae in Thailand

Tigecycline has been regarded as one of the most important last-resort antibiotics for the treatment of infections caused by extensively drug-resistant (XDR) bacteria, particularly carbapenem- and colistin-resistant Klebsiella pneumoniae (C-C-RKP). However, reports on tigecycline resistance have been growing. Overall, ~ 4000 K. pneumoniae clinical isolates were collected over a five-year period (2017-2021), in which 240 isolates of C-C-RKP were investigated. Most of these isolates (91.7%) were resistant to tigecycline. Notably, a high-risk clone of ST16 was predominantly identified, which was associated with the co-harboring of blaNDM-1 and blaOXA-232 genes. Their major mechanism of tigecycline resistance was the overexpression of efflux pump acrB gene and its regulator RamA, which was caused by mutations in RamR (M184V, Y59C, I141T, A28T, C99/C100 insertion), in RamR binding site (PI) of ramA gene (C139T), in MarR (S82G), and/or in AcrR (L154R, R13Q). Interestingly, four isolates of ST147 carried the mutated tet(A) efflux pump gene. To our knowledge, this is the first report on the prevalence and mechanisms of tigecycline resistance in C-C-RKP isolated from Thailand. The high incidence of tigecycline resistance observed among C-C-RKP in this study reflects an ongoing evolution of XDR bacteria against the last-resort antibiotics, which demands urgent action.

Carbapenem-resistant Klebsiella pneumoniae: the role of plasmids in emergence, dissemination, and evolution of a major clinical challenge

INTRODUCTION

Klebsiella pneumoniae is a major agent of healthcare-associated infections and a cause of some community-acquired infections, including severe bacteremic infections associated with metastatic abscesses in liver and other organs. Clinical relevance is compounded by its outstanding propensity to evolve antibiotic resistance. In particular, the emergence and dissemination of carbapenem resistance in K. pneumoniae has posed a major challenge due to the few residual treatment options, which have only recently been expanded by some new agents. The epidemiological success of carbapenem-resistant K. pneumoniae (CR-Kp) is mainly linked with clonal lineages that produce carbapenem-hydrolyzing enzymes (carbapenemases) encoded by plasmids.

AREAS COVERED

Here, we provide an updated overview on the mechanisms underlying the emergence and dissemination of CR-Kp, focusing on the role that plasmids have played in this phenomenon and in the co-evolution of resistance and virulence in K. pneumoniae.

EXPERT OPINION

CR-Kp have disseminated on a global scale, representing one of the most important contemporary public health issues. These strains are almost invariably associated with complex multi-drug resistance (MDR) phenotypes, which can also include recently approved antibiotics. The heterogeneity of the molecular bases responsible for these phenotypes poses significant hurdles for therapeutic and diagnostic purposes.

Fluoroquinolone resistance determinants in carbapenem-resistant Escherichia coli isolated from urine clinical samples in Thailand

Background

Escherichia coli is the most common cause of urinary tract infections and has fluoroquinolone (FQ)-resistant strains, which are a worldwide concern.

Objectives

To characterize FQ-resistant determinants among 103 carbapenem-resistant E. coli (CREc) urinary isolates using WGS.

Methods

Antimicrobial susceptibility, biofilm formation, and short-read sequencing were applied to these isolates. Complete genome sequencing of five CREcs was conducted using short- and long-read platforms.

Results

ST410 (50.49%) was the predominant ST, followed by ST405 (12.62%) and ST361 (11.65%). Clermont phylogroup C (54.37%) was the most frequent. The genes NDM-5 (74.76%) and CTX-M-15 (71.84%) were the most identified. Most CREcs were resistant to ciprofloxacin (97.09%) and levofloxacin (94.17%), whereas their resistance rate to nitrofurantoin was 33.98%. Frequently, the gene aac(6')-Ib (57.28%) was found and the coexistence of aac(6')-Ib and blaCTX-M-15 was the most widely predominant. All isolates carried the gyrA mutants of S83L and D87N. In 12.62% of the isolates, the coexistence was detected of gyrA, gyrB, parC, and parE mutations. Furthermore, the five urinary CREc-complete genomes revealed that blaNDM-5 or blaNDM-3 were located on two plasmid Inc types, comprising IncFI (60%, 3/5) and IncFI/IncQ (40%, 2/5). In addition, both plasmid types carried other resistance genes, such as blaOXA-1, blaCTX-M-15, blaTEM-1B, and aac(6')-Ib. Notably, the IncFI plasmid in one isolate carried three copies of the blaNDM-5 gene.

Conclusions

This study showed FQ-resistant determinants in urinary CREc isolates that could be a warning sign to adopt efficient strategies or new control policies to prevent further spread and to help in monitoring this microorganism.

In Vitro Activity of Cefiderocol, Cefepime-Zidebactam, and β-Lactam Combinations Versus Other Antibiotic Classes Against Various Sequence Types of Clinically Isolated Carbapenemase-Producing Klebsiella pneumoniae

Aim: This study aimed to establish the in vitro efficacy and susceptibility profiles of new β-lactam antibiotics against clinically isolated carbapenemase-producing Klebsiella pneumoniae (CPKP) strains. Materials and Methods: A total of 117 nonduplicated CPKP isolates were tested against cefiderocol, cefepime-zidebactam, ceftazidime-avibactam, tigecycline, and other 20 antibiotics by broth microdilution. The carbapenemase genes were identified using PCR and sequencing, while multilocus sequence typing established the bacterial strains. Results: Three significant sequence types (STs), including ST147, ST16, and ST11, were shown to be the dominant STs, which occupied ∼90% of the tested population. Three carbapenemase genes, blaNDM-1, blaOXA-181, and blaOXA-232, were detected. The blaNDM-1 was found in ST147 and ST16 but not in ST11, while the blaOXA-232 was not detected in ST147. The majority of ST16 isolates contained both blaNDM-1 and blaOXA-232, which was not seen in other strains. Cefiderocol, cefepime-zidebactam, and tigecycline were the most active agents against CPKP. Both MIC50 and MIC90 of these three antibiotics remained within the susceptible categories, while nearly all other antibiotics were in the resistant levels. However, in ST11, which carried only blaOXA genes without blaNDM-1, ceftazidime-avibactam was effective with the MIC90 at 2 μg/mL. In addition, amikacin was shown to have good activity in ST11. In contrast, gentamicin was active in only ST16 and ST147. Conclusions: This study is the first report that demonstrates the prevalence of CPKP, distribution of strains, resistant genes, and antimicrobial susceptibility profiles in northern Thailand. These data would contribute to appropriate individual treatment and the selection of infection control strategies.

Epidemiological characteristics of New Delhi Metallo-β-Lactamase-producing Enterobacteriaceae in the Fourth hospital of Hebei Medical University

The epidemiological characteristics of New Delhi Metallo-β-Lactamase-Producing (NDM) Enterobacteriaceae were analyzed to provide theoretical support for clarifying the distribution characteristics of carbapenem-resistant Enterobacteriaceae (CRE) in the hospital environment and early identification of susceptible patients. From January 2017 to December 2021,42 strains of NDM-producing Enterobacteriaceae were gathered from the Fourth Hospital of Hebei Medical University, primarily Escherichia coli, Klebsiella pneumoniae, and Enterobacter cloacae. The micro broth dilution method combined with the Kirby-Bauer method was used to determine the minimal inhibitory concentrations (MICs) of antibiotics. The carbapenem phenotype was detected by the modified carbapenem inactivation method (mCIM) and EDTA carbapenem inactivation method (eCIM). Carbapenem genotypes were detected by colloidal gold immunochromatography and real-time fluorescence PCR. The results of antimicrobial susceptibility testing showed that all NDM-producing Enterobacteriaceae were multiple antibiotic resistant, but the sensitivity rate to amikacin was high. Invasive surgery prior to culture, the use of excessive amounts of different antibiotics, the use of glucocorticoids, and ICU hospitalization were clinical characteristics of NDM-producing Enterobacteriaceae infection. Molecular typing of NDM-producing Escherichia coli and Klebsiella pneumoniae was carried out by Multilocus Sequence Typing (MLST), and the phylogenetic trees were constructed. Eight sequence types (STs) and two NDM variants were detected in 11 strains of Klebsiella pneumoniae, primarily ST17, and NDM-1. A total of 8 STs and 4 NDM variants were detected in 16 strains of Escherichia coli, mainly ST410, ST167, and NDM-5. For high-risk patients who have CRE infection, CRE screening should be done as soon as feasible to adopt prompt and efficient intervention measures to prevent outbreaks in the hospital.

[Regional dissemination of carbapenem-resistant Enterobacteriaceae accompanying with enhanced resistance in Northern Osaka, Japan]

With the rapid spread of multidrug-resistant bacteria, carbapenem-resistant Enterobacteriaceae (CRE) has been reported worldwide as a major concern because of limited treatment options. Carbapenem resistance is mainly due to carbapenem-ase, a carbapenem-degrading enzyme, which is mainly encoded on a plasmid to spread across bacterial species. However, there have been only small-scale attempts to determine the similarities or accommodations of the plasmids disseminating regionwide. We analysed the 230 CRE isolates carrying bla_IMP from 43 medical facilities in the northern Osaka area focusing on the plasmids, the main carriers of the drug resistance genes. Combination of whole genome sequencing and Southern blotting revealed the predominant dissemination of bla_IMP-6 by the pKPI-6 plasmid among genetically distinct isolates, as well as the emergences of derivatives that acquired various advantages. We iden-tified heteroresistance likely causing stealth transmissions, which was generated by the transcriptional regu-lation of bla_IMP-6, stabilization of bla_IMP-6 through chromosomal integration, enhanced carbapenem resistance through plasmid multimerization, or broadened antimicrobial resistance due to a single point mutation in bla_IMP-6. In this article, I dis-cussed the mechanisms of regional spread of CRE and enhancement of carbapenem resistance providing the insights to prevent their disseminations.