Prevalence of extended spectrum beta lactamases in Salmonella species isolated from patients with acute gastroenteritis.

INTRODUCTION AND AIMS: Extended-spectrum β-lactamases (ESBLs) continue to be a major problem world wide, conferring resistance to the expanded-spectrum cephalosporins. They are increasingly associated with genus Salmonella. This study aimed to determine the prevalence of ESBLs in Salmonella isolates in our region by phenotypic methods.

METHODS

One thousand stool samples of acute gastroenteritis patients were screened and 42 strains of Salmonella (19 S. typhimurium, 14 S. enteritidis, 5 S. typhi, 3 S. paratyphi B 3 and 1 S. infantis) were detected.

RESULTS

In the 3rd generation cephalosporin resistant Salmonella stains, ESBL was detected by double disc synergy test in ten isolates and by phenotypic confirmatory test in eight isolates of Salmonella. Drug resistance to various antibiotics was noted both among ESBL producers and non-ESBL producers. Resistance to chloramphenicol, nalidixic acid, norfloxacin and ciprofloxacin was noted in ESBL producers (n=4, 3, 8 and 8 of eight cases respectively) and in non-ESBL producers (n=10, 9, 16 and 13 of 34 cases, respectively). Quinolone resistance was significantly higher in ESBL producers while imipenem and cotrimoxazole resistance was significantly higher in non-ESBL producers. ESBL positive Salmonella isolates were found to be sensitive to amikacin and amoxyclav.

CONCLUSION

The proper and regular monitoring of drug resistance ESBL production among Salmonella strains were necessary for the effective therapeutic outcome.