Identification and molecular characterization of Escherichia coli blaSHV genes in a Chinese teaching hospital

Characterization of Beta-Lactam Resistome of Escherichia coli Causing Nosocomial Infections

Nosocomial infections caused by Escherichia coli pose significant therapeutic challenges due to the high expression of genes encoding antimicrobial drug resistance. In this study, we investigated the conformation of the beta-lactam resistome responsible for the specific pattern of resistance against beta-lactam antibiotics. A total of 218 Escherichia coli strains were isolated from in-hospital patients diagnosed with nosocomial infections, obtained from various sources such as urine (n = 49, 22.48%), vaginal discharge (n = 46, 21.10%), catheter tips (n = 14, 6.42%), blood (n = 13, 5.96%), feces (n = 12, 5.50%), sputum (n = 11, 5.05%), biopsies (n = 8, 3.67%), cerebrospinal fluid (n = 2, 0.92%) and other unspecified discharges (n = 63, 28.90%). To characterize the beta-lactam resistome, all strains were subjected to antibiotic dilution tests and grown in beta-lactam antibiotics supplemented with Luria culture medium. Subsequently, multiplex PCR and next-generation sequencing were conducted. The results show a multi-drug-resistance phenotype, particularly against beta-lactam drugs. The primary determinant of this resistance was the expression of the blaTEM gene family, with 209 positive strains (95.87%) expressing it as a single gene (n = 47, 21.6%) or in combination with other genes. Common combinations included blaTEM + blaCTX (n = 42, 19.3%), blaTEM + blaCTX + blaSHV (n = 13, 6%) and blaTEM + blaCTX + blaBIL (n = 12, 5.5%), among others. The beta-lactam resistome of nosocomial Escherichia coli strains isolated from inpatients at the "October first" Regional Hospital of ISSSTE was predominantly composed of members of the blaTEM gene family, expressed in various configurations along with different members of other beta-lactamase gene families.

Molecular Epidemiology of Extended-Spectrum Beta-Lactamase and AmpC Producing Enterobacteriaceae among Sepsis Patients in Ethiopia: A Prospective Multicenter Study

Extended-spectrum beta-lactamases (ESBLs) and AmpC producing Enterobacteriaceae are public health threats. This study aims to characterize ESBL and AmpC producing Enterobacteriaceae isolated from sepsis patients. A multicenter study was conducted at four hospitals located in central (Tikur Anbessa and Yekatit 12), southern (Hawassa) and northern (Dessie) parts of Ethiopia. Blood culture was performed among 1416 sepsis patients. Enterobacteriaceae (n = 301) were confirmed using MALDI-TOF and subjected for whole genome sequencing using the Illumina (HiSeq 2500) system. The overall genotypic frequencies of ESBL and AmpC producing Enterobacteriaceae were 75.5% and 14%, respectively. The detection of ESBL producing Enterobacteriaceae at Hawassa, Yekatit 12, Tikur Anbessa and Dessie was 95%, 90%, 82% and 55.8%, respectively. The detection frequency of bla_CTX-M, bla_TEM and bla_SHV genes was 73%, 63% and 33%, respectively. The most frequently detected ESBL gene was bla_CTX-M-15 (70.4%). The common AmpC genes were bla_ACT (n = 22) and bla_CMY (n = 13). Of Enterobacteriaceae that harbored AmpC (n = 42), 71% were ESBL co-producers. Both bla_TEM-1B (61.5%) and bla_SHV-187 (27.6%) were the most frequently detected variants of bla_TEM and bla_SHV, respectively. The molecular epidemiology of ESBL producing Enterobacteriaceae showed high frequencies and several variants of ESBL and AmpC genes. Good antimicrobial stewardship and standard bacteriological laboratory services are necessary for the effective treatment of ESBL producing Enterobacteriaceae.

Hospital Wastewater-Important Source of Multidrug Resistant Coliform Bacteria with ESBL-Production

This work compares the prevalence of antibiotic resistant coliform bacteria in hospital wastewater effluents in Slovak (SR) and Czech Republic (ČR). It also describes selected antibiotic resistant isolates in view of resistance mechanism and virulence factor. The highest number of multidrug resistant bacteria was detected in samples from the hospital in Valašské Meziříčí (ČR). More than half of resistant isolates showed multidrug resistance phenotype as well as strong ability to form biofilm. In 42% of isolates efflux pump overproduction was detected together with tetA and tetE genes. The production of extended-spectrum β-lactamases in coliform isolates was encoded mainly by bla_TEM, bla_CTX-M-2 and bla_CTX-M-8/25 genes. About 62% of resistants contained a combination of two or more extended spectrum beta-lactamases (ESBL) genes. Our results strengthen the fact that hospital effluents are a source of multidrug resistant bacteria which can spread their resistance genes to other bacteria in wastewater treatment plants (WWTPs). Accordingly, hospital wastewater should be better treated before it enters urban sewerage.

Prevalence of Aminoglycoside Resistance Genes and Molecular Characterization of a Novel Gene, aac(3)-IIg, among Clinical Isolates of the Enterobacter cloacae Complex from a Chinese Teaching Hospital

Members of the Enterobacter cloacae complex are important opportunistic human pathogens capable of causing a wide variety of infections. During recent decades, aminoglycoside-resistant E. cloacae complex isolates have increasingly been reported and have become a major concern. Here, we employed high-throughput sequencing in combination with specific PCR assays to investigate the prevalence of aminoglycoside resistance genes among 170 isolates of the E. cloacae complex collected from a teaching hospital in Wenzhou, China. A total of 12 known genes [aphA-1, strA, strB, aac(6')-IIc, aadA2, aac(3)-IId, aadB, aadA1, rmtB, armA, aadA5, and aac(6')-Ie-aph(2'')-Ia] and 1 novel gene [aac(3)-IIg] were identified, with aphA-1 (71.18%), strA (55.29%), and strB (52.35%) being the most prevalent, and aac(3)-IIg was detected with a positive rate of 21.76% (37/170). The aac(3)-IIg gene was 810 bp in length and encoded a protein that shared 72 to 78% identities with previously known AAC(3)-II aminoglycoside 3-N-acetyltransferases. The MICs of gentamicin and tobramycin were 512 μg/ml and 64 μg/ml, respectively, when aac(3)-IIg was cloned into Escherichia coli DH5α. All aac(3)-IIg-positive isolates exerted broad aminoglycoside resistance profiles, mediated by the coexistence of multiple resistance genes. Moreover, aminoglycoside resistance and resistance genes were found to be transferable in most strains (24/37). Nevertheless, pulsed-field gel electrophoresis (PFGE) and dendrogram analysis showed clonal diversity among these isolates. S1 nuclease PFGE, Southern hybridization, and whole-genome sequencing indicated that aac(3)-IIg was located on transferable as well as nontransferable plasmids of various sizes. The analysis of the genetic environment suggested that aac(3)-IIg is embedded within a class 1 integron, with IS26 playing an important role in its mobility.