Prevalence and molecular identification of Salmonella spp. isolated from commercialized eggs at Ibague, Colombia

Abstract

Salmonella is a Gram-negative bacterium responsible for salmonellosis, a disease transmitted by the consumption of contaminated poultry products such as eggs and raw chicken meat. The Salmonella serovars present on the surface of eggs marketed in Ibague city are currently unknown. To address this issue, an observational cross-sectional study was designed to estimate Salmonella spp. prevalence on the surface of eggs sold in Ibague city from January - August 2014. A total of 1,705 eggs were collected from stores and supermarkets, and 341 samples (pools of five eggs each) were processed for Salmonella spp. isolation, followed by serotyping and typing by multiple PCR. Salmonella spp. prevalence in egg surface was 2.93%, and S. Enteritidis and S. Paratyphi B were the main serotypes present. S. Enteritidis and S. Paratyphi B were correctly identified by three multiplex PCR directed to amplifly the rfB and wzX, fliC and fljB genes for serogroup and serovar identification, respectively. The frequency of cleaning and disinfection (OR= 19,8), the presence of long nails (OR=5,46) and storage temperature (OR=10,05) were identified as potential risk factors for Salmonella spp. contamination at the market place. It is concluded that S. Enteritidis and S. ParatyphiB, two potential human pathogens, were isolated from the surface of eggs marketed in Ibague city,  and multiplex PCR-based typing correlated well with the conventional serotyping in identifying those serovars.

Key words: Poultry, eggshell, serovars, transmission.