ABSTRACT
Enterococci are ubiquitous microorganisms, found as part of the normal intestinal microbiota of many animals. They can be present in food products, for example, the Portuguese dry fermented sausage chouriço. Twenty enterococci were isolated from chouriço in two processing units; after identification and typification by conventional-molecular methods, the isolates were screened for virulence factors and antibiotic resistance. Identification allocated all enterococci to the species Enterococcus faecalis, and PCR fingerprinting demonstrated that each isolate was specific to the processing unit and chouriço from which it was recovered. Regarding the screening for virulence factors, 1 strain produced cytolysin and 4 were gelatinase positive, but none produced lipase. The ace gene was detected in 1 enterococci, ebpABC and efaA(fs) in 16 isolates each, esp in 3, fsrB in 5, gelE in 7, and cylA in 1. A multiresistant phenotype was observed in 8 isolates, 6 belonging to factory A. The antibiotic resistance gene ere(B) was detected in 9 enterococci, whereas the genes tet(M), aac(6')-Ie-aph(2''), and vanA were detected in 8 isolates each. As some of the E. faecalis chouriço isolates present a multiresistant profile and harbor virulence and/or resistance genes, to assess further the safety of Portuguese dry sausages, a larger number of products and processing units must by analyzed.
Subject(s)
Anti-Bacterial Agents/pharmacology , Drug Resistance, Bacterial , Enterococcus/isolation & purification , Meat Products/microbiology , Virulence Factors/genetics , Animals , Colony Count, Microbial , Consumer Product Safety , Drug Resistance, Bacterial/genetics , Drug Resistance, Multiple, Bacterial , Enterococcus/drug effects , Enterococcus/pathogenicity , Fermentation , Humans , Microbial Sensitivity Tests , PortugalABSTRACT
AIMS: The role of enterococci in food fermentation and as probiotics counteracts with their increasing importance as human pathogens. Over the years, several virulence factors have been described, mainly in clinical strains but also in food isolates. However, differential expression of such traits may modulate the pathogenic potential of the harbouring enterococci. To further unravel such differential response, this study aims to identify environmental cues responsible for triggering the expression of virulence-related genes. METHODS AND RESULTS: The differential expression of eight virulence-related genes (cylMBAI, agg, esp, efaA(fs) and efaAfm) in 16 enterococci from distinct origins, grown in conditions simulating environmental colonization and infection sites, was analysed by reverse transcriptase PCR. The expression profiles were environmental and strain-dependent, because no constant response was observed neither for clinical nor food enterococci. CONCLUSIONS: Virulence expression profiles are strain-specific and unrelated with strain's origin or species allocation. SIGNIFICANCE AND IMPACT OF THE STUDY: The current study constitutes the first approach aimed at the evaluation of the differential expression of enterococcal virulence-related genes combining so many growth environments, enterococcal species and origins. So, with this investigation, we intend to contribute to the clarification of enterococcal pathogenicity potential, especially for food strains.
