Abstract
Members of the family Enterobacteriaceae include several human pathogens that can be acquired through contaminated food and water. In this study, the incidence of extended spectrum β-lactamase (ESBL)-producing enterobacteria was investigated in fresh seafood sold in retail markets. The ESBL-positive phenotype was detected in 169 (78.60%) isolates, with Escherichia coli being the predominant species (53), followed by Klebsiella oxytoca (27), and K. pneumoniae (23). More than 90% of the isolates were resistant to third generation cephalosporins, cefotaxime, ceftazidime, and cefpodoxime. Sixty-five percent of the isolates were resistant to the monobactam drug aztreonam, 40.82% to ertapenem, and 31.36% to meropenem. Resistance to at least five antibiotics was observed in 38.46% of the isolates. Polymerase Chain Reaction (PCR) analysis of ESBL-encoding genes detected blaCTX, blaSHV, and blaTEM genes in 76.92%, 63.3%, and 44.37% of the isolates, respectively. Multiple ESBL genes were detected in majority of the isolates. The recently discovered New Delhi metallo-β-lactamase gene (blaNDM-1) was detected in two ESBL+ isolates. Our study shows that secondary contamination of fresh seafood with enteric bacteria resistant to multiple antibiotics may implicate seafood as a potential carrier of antibiotic resistant bacteria and emphasizes an urgent need to prevent environmental contamination and dissemination of such bacteria.
Highlights
Members of the family Enterobacteriaceae, which include important food-borne pathogens such as Salmonella enterica and Escherichia coli, are known to cause diverse types of infections ranging from wound infection to meningitis, and are known agents of nosocomial infections
Fresh seafood sold in retail markets in India are often found contaminated with coliform bacteria which are antibiotic resistant [23], but no studies have focused on ESBL+ Enterobacteriaceae
Our study reports the incidence of ESBL genes in diverse members of Enterobacteriaceae family for the first time, a few past studies have reported the occurrence of antibiotic resistant E. coli in seafood
Summary
Members of the family Enterobacteriaceae, which include important food-borne pathogens such as Salmonella enterica and Escherichia coli, are known to cause diverse types of infections ranging from wound infection to meningitis, and are known agents of nosocomial infections. The chemotherapeutic options for enterobacteria are becoming severely constricted owing to the development of resistance to multiple antibiotics, the most notable among these being resistance to β-lactam group of antibiotics such as cephalosporins and carbapenems [1]. ESBLs confer resistance to third generation cephalosporins (e.g., cefotaxime, ceftazidime) and monobactams (e.g., aztreonam), but cannot hydrolyze cephamycins (cefoxitin) or carbapenems (imipenem), and are inhibited by β-lactamase inhibitors such as clavulanic acid [7]. Carbapenems are the antibiotics of choice against ESBL-producing bacteria, but the occurrence of carbapenem resistant enterobacteria (CRE) producing plasmid-encoded metallo-β-lactamases with carbapenemase activity have emerged worldwide [8,9]. In 2008, a new β-lactamase, the New Delhi metallo-β-lactamase (blaNDM-1) capable of hydrolyzing all β-lactams with the exception of aztreonam, was identified in a clinical isolate of Klebsiella pneumoniae [10]. Studies from India and other countries have reported the occurrence of blaNDM-harboring bacteria in the environment [13,14]
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