A survey for serotyping, antibiotic resistance profiling and PFGE characterization of and the potential multiplication of restaurant Salmonella isolates

Abstract

Aims: The aims of this research were (1) to determine the occurrence of Salmonella in Irish restaurant kitchens and (2) to investigate the serovar, genotype, antibiotic resistance profile and survival/growth profile of the Salmonella under catering chilled storage and temperature abuse conditions.

Methods: Five sites/tools in each of 200 randomly selected restaurant kitchens were examined for the presence of presumptive Salmonella spp. by enrichment. Serotyping, antibiotic resistance studies and genotyping were performed using the Kauffmann-White, CLSI and PulseNet methods, respectively. Survival/growth was investigated in milk, meat and vegetable products.

Results: Presumptive isolates from 15 of the 200 restaurant kitchens were recovered and confirmed as Salmonella positive. Seven different serovars showing a variety of antibiotic resistance profiles were detected. PFGE profiles suggested that isolates from geographically adjacent restaurants were related. Salmonella survived in foods stored at typical catering refrigeration temperatures and increased by approximately 0.8 log(10) CFU ml(-1) per day in food products stored under conditions of thermal abuse (20 degrees C).

Conclusions: Inadequate hygiene has resulted in contamination of restaurant kitchens with Salmonella, which may persist/multiply in cross-contaminated foods.

Significance and impact of the study: This study highlights the need for greater hygiene in restaurant kitchens coupled with rapid chilling of food not for immediate consumption and reheating before subsequent serving.