Prevalence and Susceptibility of Extended Spectrum Beta-Lactamases in Urinary Isolates of Escherichia Coli in a Tertiary Care Hospital, Chennai-South India (Original Work) (Report)
INTRODUCTION Resistant bacteria are emerging worldwide as a threat to favorable outcome in the treatment of common infections in community and hospital settings (1). Among the wide array of antibiotics, [beta]-lactams are the most widely used agents. The most common cause of resistance to [beta]-lactam antibiotics is the production of [beta]-lactamases. Emergence of resistance to [beta]-lactam antibiotics began even before the first [beta]-lactam, penicillin, was developed. The first plasmid-mediated [beta]-lactamase TEM-1 was originally isolated from blood culture of a patient named Temoniera in Greece, in the early 1960s (2). TEM-1 being plasmid and transposon mediated has facilitated its spread to other species of bacteria. Another common plasmid-mediated [beta]-lactamase SHV-1 (sulfhydryl variable), is chromosomally encoded in the majority of isolates of K. pneumoniae but is usually plasmid-mediated in E. coli. Over the years, many new [beta]-lactam antibiotics have been developed; however, with each new class of antibiotic, a new [beta]-lactamase emerged that caused resistance to that class of drug. Presumably, the selective pressure imposed by the use and overuse of new antibiotics in the treatment of patients has resulted in the emergence of new variants of [beta]-lactamase.