Abstract

OCCURRENCE OF CTX-M-I AND CTX-M-III GENES ON PLASMIDS OF SHIGELLA SPECIES ISOLATED FROM CASES OF DIARRHEA IN BAGHDAD

Ibtesam Ghadban Auda

Abstract

The CTX-M-type β-lactamases represent a group with a typical extended-spectrum β-lactamase (ESBL)-resistance phenotype. These enzymes, encoded by transferable plasmids. They have a preferential hydrolysis of cefotaxime over ceftazidime. The CTX-M-type β- lactamases have been described in species of Enterobacteriaceae. This study was designed to investigate of the occurrence of CTX-M-I and CTX-M-III types in Shigella species isolated from cases of diarrhea in Iraq. Isolation and identification of Shigella species from cases of diarrhea in Iraq. Susceptibility test, plasmid DNA extraction, and electrophoresis were performed. Using specific primers, CTX-M-I and CTX-M-III enzyme genes were amplified by duplex PCR. Most of isolated Shigella species was Shigella sonnei, followed by S. flexneri then S. dysenteriae. Susceptibility test shows that most of these isolates were resistant to β- lactam antibiotics tested except imipenem. Amplification of CTX-M-I and CTX-M-III enzyme genes reveals the absence of CTX-M-III in all Shigella species, and CTXM- I was predominant. As a conclusion, Shigella sonnei was the most predominant Shigella species in this study. Shigella species were resistant to β- lactam antibiotics tested except imipenem; this may be due to presence of CTX-M-I type of β- lactamases that were predominant in Shigella species in this study.

Keywords: CTX-M-I, CTX-M-III, Shigella species, duplex PCR.