Asymptomatic carrier rate and sensitivity pattern of Salmonella typhi among food handlers in Karachi


Investigators:                      Taranum Ruba Siddiqui, Safia Bibi, Ayaz Mustafa

Institution:                     PMRC, Jinnah Postgraduate Medical Centre, Karachi

Duration:                       15 months

Background:  Salmonellosis comprises of typhoidal and non typhoidal infection. Salmonella typhi and paratyphi A & B cause typhoid fever while non- typhoidal salmonella causes food poising.  

Objective: To determine carrier rate and antimicrobial susceptibility pattern of typhoidal and non-typhoidal Salmonella species among food handlers in Karachi.

Setting: Five different randomly selected towns of Karachi city were visited for data collection and sampling.

Methods: Cross sectional study which was conducted from January 2011 to January 2012. Total 220 food handlers were recruited from different food streets of randomly selected five towns of Karachi. Three consecutive stool samples were collected from each food handler in Carry Blair transport media. Culture, biochemical identification, serotyping and sensitivity test were performed in Microbiology Lab of PMRC. Statistical analysis was done on computer package SPSS 17.0.

Results:  Out of 220 food handlers, 209 consented to participate. Total 19 (9.1%) food handlers were positive for Salmonella species. Serotyping of these positive isolates revealed 7 (36.8%) Salmonella typhi, 1 (5.2%) Salmonella paratyphi A and B each, and 10 (52.6%) were non- typhoidal Salmonella species. The resistance pattern of these isolates showed 89.4% to Ampicillin, followed by 26.3% to Cotrimoxazole, 15.7% to Nalidixic acid, and 5.2% to Chloramphenicol and Ceftrixone/ Cefixime each. All 19 isolates were sensitive to Ofloxacin.

Conclusion: Carrier rate of both typhoidal and non typhoidal Salmonella in Food handlers was 9%, indicating that they might be contributing to the high endemicity of typhoid fever in Karachi, Pakistan.

Recommendations: Food handlers should be screened periodically for salmonella carrier state and education for the proper hygienic practices should be delivered to them to avoid the transmission of infection

Publication status:  In preparation for submission to Journal