EMERGING RESISTANCE

ANTIBIOGRAMS OF SALMONELLA STRAINS

Abstract

Objectives: To study the bacteriological profile of enteric fever and their antibiotic
sensitivity pattern to commonly used antibiotics in view of emerging resistance at Civil Hospital
Karachi (C.H.K.) and provide a guideline for making a protocol for empirical antibiotic therapy
where culture facilities are not available. Methodology: Design: Descriptive laboratory Based
study. Place and Duration of study: The study was conducted from 1st January, 2010 till 30th
June, 2012 at the Central Lab, Civil Hospital Karachi. Patients and Methods: A cross sectional
analysis was done on a total of 37,805 blood specimens sent for C/S from the entire inpatient and
outpatient departments to the central lab, CHK. All blood cultures were inoculated in thioglycolate
broth and incubated at 37° for 7 days. Positive blood cultures were processed, colonies were
identified using standard biochemical tests and antibiotic susceptibility was checked by Kirby-
Bauer disc diffusion method as per CLSI criteria. Results: Out of these specimens, 430 samples
were found positive for the salmonella strains, among them 395 (91.86%) were Salmonella typhi
and 35 (8.14%) were Salmonella paratyphi A. Salmonella infection was more common in male
(55.85%) and more prevalent in children under 10 years of age (34.88%). The resistance pattern
for Amoxicillin, Chloramphenicol, Co-trimoxazole, was (29%), (41%) and (5%) respectively;
while the resistance was found to be higher in the commonly prescribed drugs belonging to first
and second generation of cephalosporins and flouroquinolones. Conclusion: Amoxicillin and
Chloramphenicol, the first line of drugs for the treatment of enteric fever are losing their efficacy
and most of the organisms have developed resistance. Also, resistance against the second line
of therapy, involving the use of cephalosporins and quinolones is rapidly emerging.