Dissemination of extended-spectrum beta-lactamase-producing Enterobacteriaceae in intensive care units of a medical center in Taiwan

Epidemiology of extended-spectrum β-lactamases in Enterobacterales in Taiwan for over two decades

The emergence of antimicrobial resistance among microorganisms is a serious public health concern, and extended-spectrum β-lactamases (ESBL)-producing Enterobacterales is one of the major concerns among antibiotic-resistant bacteria. Although the prevalence of ESBL in Enterobacterales has been increasing with time, the prevalence of ESBL could differ according to the species, hospital allocation, sources of infections, nosocomial or community acquisitions, and geographic regions. Therefore, we conducted a comprehensive review of the epidemiology of ESBL-producing Enterobacterales in Taiwan. Overall, the rates of ESBL producers are higher in northern regions than in other parts of Taiwan. In addition, the genotypes of ESBL vary according to different Enterobacterales. SHV-type ESBLs (SHV-5 and SHV-12) were the major types of Enterobacter cloacae complex, but Serratia marcescens, Proteus mirabilis, Escherichia coli, and Klebsiella pneumoniae were more likely to possess CTX-M-type ESBLs (CTX-M-3 and CTX-M-14). Moreover, a clonal sequence type of O25b-ST131 has been emerging among urinary or bloodstream E. coli isolates in the community in Taiwan, and this clone was potentially associated with virulence, ESBL (CTX-M-15) production, ciprofloxacin resistance, and mortality. Finally, the evolution of the genetic traits of the ESBL-producing Enterobacterales isolates helps us confirm the interhospital and intrahospital clonal dissemination in several regions of Taiwan. In conclusion, continuous surveillance in the investigation of ESBL production among Enterobacterales is needed to establish its long-term epidemiology.

Characterization of IS26-composite transposons and multidrug resistance in conjugative plasmids from Enterobacter cloacae

SHV-12 is the most widespread resistance determinant of Enterobacter cloacae in Taiwan; however, blaSHV-12 has rarely been mobilized. Six multidrug-resistant E. cloacae isolates were collected. After conjugal transfer, plasmid profiling and analysis of incompatibility groups was performed to characterize the genetic context of blaSHV-12 -containing fragments. The presence of mobile genetic elements was demonstrated by PCR, cloning, sequencing and bioinformatics analyses. Four different β-lactamase genes (blaTEM-1 , blaSHV-12 , blaCTX-M-3 and/or blaCTX-M-14 ) were observed in the conjugative plasmids belonging to the IncHI2 (n = 4), IncI1 or IncP incompatibility groups. The IS26-blaSHV-12 -IS26 locus was located in five different genetic environments. A novel structural organization of a class 1 integron with the aac(6')-IIc cassette truncated by IS26 was identified in one isolate. Thus, blaSHV-12 was obtained from different plasmids through IS26-mediated homologous recombination. IS26 plays a vital role in the distribution of mobile resistance elements between different plasmids found in multidrug-resistant E. cloacae isolates.

Clinical and Molecular Epidemiology of Extended-Spectrum Beta-Lactamase-Producing Klebsiella spp.: A Systematic Review and Meta-Analyses

Healthcare-related infections caused by extended-spectrum beta-lactamase (ESBL)-producing Klebsiella spp. are of major concern. To control transmission, deep understanding of the transmission mechanisms is needed. This systematic review aimed to identify risk factors and sources, clonal relatedness using molecular techniques, and the most effective control strategies for ESBL-producing Klebsiella spp. A systematic search of PubMed, Embase, and Outbreak Database was performed. We identified 2771 articles from November 25th, 1960 until April 7th, 2014 of which 148 were included in the systematic review and 23 in a random-effects meta-analysis study. The random-effects meta-analyses showed that underlying disease or condition (odds ratio [OR] = 6.25; 95% confidence interval [CI] = 2.85 to 13.66) generated the highest pooled estimate. ESBL-producing Klebsiella spp. were spread through person-to-person contact and via sources in the environment; we identified both monoclonal and polyclonal presence. Multi-faceted interventions are needed to prevent transmission of ESBL-producing Klebsiella spp.

Large IncHI2-plasmids encode extended-spectrum β-lactamases (ESBLs) in Enterobacter spp. bloodstream isolates, and support ESBL-transfer to Escherichia coli

We investigated the prevalence of extended-spectrum β-lactamases (ESBLs) in Enterobacter spp. bloodstream isolates from 19 hospital laboratories in Norway during 2011. A total of 62/230 (27%) isolates were resistant to third-generation cephalosporins and four (1.7%) were ESBL-positive; blaCTX -M-15 (n = 3) and blaSHV -12 (n = 1). This is comparable to the prevalence of ESBLs in clinical isolates of Escherichia coli and Klebsiella pneumoniae in Norway during the same period. All ESBL-positive isolates were multidrug resistant (MDR) and harboured plasmid-mediated quinolone resistance. Three isolates supported transfer of large IncHI2-plasmids harbouring ESBL- and MDR-encoding genes to E. coli recipients by in vitro conjugation.

Bacteremia due to extended-spectrum-beta-lactamase-producing Enterobacter cloacae: role of carbapenem therapy

Enterobacter cloacae is an important nosocomial pathogen. However, few studies specifically dealing with the clinical characteristics and outcome of extended-spectrum beta-lactamase (ESBL)-producing E. cloacae infections have been published. During an 8-year period in a medical center, of 610 E. cloacae bacteremic isolates, 138 (22.6%) with ESBL genes were designated the ESBL group, and 120 (19.6%) cefotaxime-nonsusceptible isolates without the ESBL phenotype and genes were designated the control group. Of the former group of isolates, 133 (96.3%) carried the bla(SHV-12) gene, 3 (2.1%) had bla(CTX-M3), and 2 (1.4%) had both the bla(SHV-12) and bla(CTX-M3) genes. After patients under the age of 18 years were excluded, there were 206 adults with E. cloacae bacteremia, and these consisted of 121 patients in the ESBL group and 85 in the control group. More episodes of hospital-onset and polymicrobial bacteremia, increased severity of illness, more cases of bacteremia onset in intensive care units (ICUs), and longer stays in the hospital and ICU after bacteremia onset were noted in the ESBL group. However, the crude and sepsis-related mortality rates in two groups were similar. Of the ESBL group, the in-hospital sepsis-related mortality rate of patients definitively treated by a carbapenem was lower than that of those treated by noncarbapenem beta-lactams (5/53, or 9.4%, versus 13/44, or 29.5%; P = 0.01) though the difference was not significant in the hierarchical multivariate analysis (P = 0.46). Among 62 patients with follow-up blood cultures within 14 days of bacteremia onset, breakthrough bacteremia was more common in those treated by a noncarbapenem beta-lactam agent than in those treated by a carbapenem (18/31, or 58.0%, versus 3/31, or 9.6%; P < 0.001). Thus, carbapenem therapy for ESBL-producing E. cloacae that cause bacteremia may provide therapeutic benefits.

Genotyping of extended-spectrum β-lactamase-producing enterobacteriaceae isolated from patients with antibiotic-associated diarrhea

AIM: To genotype extended-spectrum β-lactamase (ESBL)-producing enterobacteriaceae isolated from patients with antibiotic-associated diarrhea.

METHODS: The feces samples were collected from patients with antibiotic-associated diarrhea and cultured to isolate ESBL-producing enterobacteriaceae. Klebsiella pneumoniae carbapenemase production was evaluated by the modified Hodge test. Metallo-β-lactamase production was determined by the imipenem-EDTA double-disk synergy test. Antibiotic resistance genes were amplified by polymerase chain reaction (PCR). The sequences of PCR products were determined and compared with those deposited in GenBank.

RESULTS: Fifty Klebsiella pneumoniae strains, 21 Escherichia coli strains and 18 Proteus strains were isolated. Of all isolated strains, 64 carry ESBLs of the CTX-type, 68 carry ESBLs of the TEM-type, and 21 carry ESBLs of the SHV-type. CTX-, TEM- and SHV-type ESBLs were present in 84% (42/50), 76% (38/50) and 15% (7/50) of Klebsiella pneumoniae isolates, respectively. TEM- and CTX-type ESBLs were present in 100% (18/18) and 40% (7/18) of Proteus isolates, respectively. No SHV-type ESBLs were detected in Proteus isolates. CTX-, TEM- and SHV-type ESBLs were present in 100% (21/21), 83% (17/21) and 83% (17/21) of Escherichia coli isolates, respectively.

CONCLUSION: The enterobacteriaceae isolated from patients with antibiotic-associated diarrhea in our study mainly carry TEM- and CTX-type ESBLs.

A 7-year surveillance for ESBL-producing Escherichia coli and Klebsiella pneumoniae at a university hospital in Taiwan: the increase of CTX-M-15 in the ICU

To monitor the changing trend of extended-spectrum beta-lactamase (ESBL)-producing bacteria, a 7-year continuous study was launched in 2001 at the largest tertiary hospital in Taiwan. A significant increase over the study period was evident for ESBL-producing isolates of Escherichia coli (4.8-10.0%) and Klebsiella pneumoniae (15.0-23.4%). Molecular investigation conducted in three separate periods revealed the prevalent ESBL types and their genetic relatedness. CTX-M-producing isolates (73.8%) were more prevalent than SHV-type ESBLs (37.0%), the most frequent being CTX-M-14 (34.3%), CTX-M-3 (25.9%), and SHV-12 (25.7%). However, a marked increase of CTX-M-15-producing isolates from 2.1% in 2002 to 29.6% in 2007 was also noted. The increase of ESBL-producing isolates in both species may be mainly due to the horizontal transmission of resistance plasmids, while clonal expansion of some epidemic strains further added to the dispersion of ESBL-producing K. pneumoniae.