The Frequency of Salmonella Serotypes in Pasteurized and Unpasteurized Creams Offered in Local Markets and Their Antibiotic Resistance Patterns

Salmonella species is one of the important pathogens causing food poisoning and gastroenteritis. The aim of the present study was to assess the quality of traditional creams as regards bacterial contamination.

This was a cross-sectional study including a total of 250 traditional cream and 50 pasteurized cream samples collected in the south of Tehran retail shops. The samples were diluted in a phosphate-buffered saline, transferred to a rappaport-vassiliadis salmonella (rvs) enrichment broth according to the CDC procedures and incubated at 37° C in Hektoen enteric agar and bismuth sulfite agar media for 24 hours. Antimicrobial susceptibility testing was done using the Clinical and Laboratory Standards Institute (CLSI) procedures. On the following day the suspected colonies were examined for phenotype and finally confirmed by the API 20 E test.

Of the 250 unpasteurized cream samples 15 (6%) were contaminated with Salmonella. Of the 7 serotypes identified, the most frequent Salmonella serotype was the infantis serotype with 7 cases (33.3%). Furthermore, Coliform bacteria such as Escherichia coli, Enterobacter, Klebsiella and Citrobacter were also isolated. The highest antibiotic resistance was to nalidixic acid (93.3%), tetracycline (73.3%) and trimethoprim (66.7%). None of the pasteurized cream samples was contaminated with Salmonella.

The results confirm the need for more effective control and monitoring of the traditionally prepared cream marketed in the city by the Food Control Authority. In addition, educating the public about the consumption of pasteurized cream can play a good role in reducing foodborne illnesses.