The discovery of highly diverse ESBL-producing bacteria and metallo-β-lactamases, particularly bla(IMP), in polluted river water raises alarms with regard to the potential dissemination of antibiotic-resistant bacteria in communities through river environments.

Antimicrobial resistance is a major health problem worldwide, but marked variations in the resistance profiles of bacterial pathogens are found between countries and in different patient settings. In Tunisia, the strikingly high prevalence of resistance of bacteria to penicillins and cephalorosporins drugs including fourth generation in clinical isolates of Gram negative bacteria has been reported. During 30 years, the emerging problem of extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae isolates is substantial, and some unique enzymes have been found. Recently, evidence that Gram-negative bacteria are resistant to nearly all available antimicrobial agents, including carbapenems, have emerged.

An extremely drug-resistant Enterobacteriaceae species emerged in Kasserine Hospital, Tunisia between 2009 and 2010 causing a local outbreak. We aimed to characterize extended-spectrum β-lactamase (ESBL) and metallo-β-lactamase (MBL)-producing Enterobacteriaceae from the hospital environment. Swabs were collected from ten different wards from Kasserine Hospital, Tunisia. A total of 46 isolates were cultured onto MacConkey agar supplemented with ceftazidime to select for ESBL-producing Enterobacteriaceae. Identification and susceptibility patterns were performed using Phoenix-automated phenotypic identification criteria. Extended spectrum β-lactamases (ESBLs) were detected using cefepime ESBL E-test. Colony blotting was first used to detect the occurrence of bla(SHV) , bla(CTX-M) , bla(CMY) , bla(IMP) , and bla(VIM) genes. PCR was used to amplify these genes, and the amplicons were sequenced and analyzed. Total DNA was digested with XbaI, and PFGE was used to type the major isolates that produced IMP-1. Among the 46 isolates, 63% were Klebsiella pneumoniae, 13% were Escherichia coli, 8.7% were Proteus mirabilis, 6% were Enterobacter cloaceae, 4.3% were Providencia rettgeri, 2.5% were Serratia marcescens, and 2.5% were Pantoea agglomerans. PCR amplification and DNA sequencing showed that hospital environment isolates produced SHV-125, CTX-M-15, CMY-2 ESBLs, and IMP-1 and VIM-2 MBLs. PFGE typing showed the emergence of IMP-1 MBL-producing K. pneumoniae isolates that were not clonal. In this study, we report the first characterization of IMP-1 and VIM-2 MBL-producing K. pneumoniae and E. coli isolates collected from Kasserine Hospital, Tunisia.

To characterize the extended-spectrum β-lactamases (ESBLs) as well as their genetic environment in different isolates of Escherichia coli from patients with repeated urinary tract infections, large multidrug resistance (MDR) plasmids have been found. Definitive evidence for the presence of an A/C incompatibility complex (IncA/C) plasmid in the MDR isolates was provided by the probing of plasmids extracted from the clinical isolates. Conjugation experiments showed that bla genes were transferred by conjugation from the ten E. coli clinical isolates to E. coli XL1-Blue recipient. A comparative restriction fragment length polymorphism (RFLP) analysis of these plasmids showed that they are genetically similar, while the overall similarity of these plasmids supports the likelihood of recent movements among these E. coli isolates. Polymerase chain reaction (PCR) amplification and sequencing of the amplicons showed that the IncA/C plasmids harbor two ESBLs, identified as TEM-52 and CTX-M-15. Analysis of the plasmid DNA surrounding the bla (CTX-M-15) gene in the clinical isolates under study revealed a partially truncated fragment of ISEcp1 tnpA transposase. This result indicates the variety of genetic events that have enabled associations between ISEcp1 sequences and bla (CTX-M-15) genes in these clinical isolates.