Diversity and Safety Aspects of Coagulase-Negative Staphylococci in Ventricina del Vastese Italian Dry Fermented Sausage

Abstract

Ventricina del Vastese is a traditional dry fermented sausage from Central Italy not yet characterized for the occurrence, identity and safety of coagulase-negative staphylococci (CNS), a bacterial group technologically important for this kind of product. Therefore, in this study, 98 CNS isolates from four manufacturers were differentiated using repetitive element palindromic PCR (Rep-PCR) and identified using 16S rRNA gene sequencing. These were examined for genes encoding biogenic amine (BA) production, resistance to aminoglycosides, β-lactams, tetracyclines and staphylococcal enterotoxins (SEs). Staphylococcus succinus (55%) predominated, followed by S. xylosus (30%), S. epidermidis (7.4%), S. equorum (3.1%), S. saprophyticus (3.1%) and S. warneri (1%). One S. succinus subsp. casei isolate was slightly β-hemolytic. SEs and the histidine decarboxylase gene hdcA were not detected, whereas the tyrosine decarboxylase gene tdcA was detected in four S. xylosus isolates. The blaZ beta-lactamase gene in an S. equorum isolate, tetracycline resistance genes tetK in six S. succinus isolates and tetA in one S. succinus isolate also bearing tetK were found. The product examined is characterized by a peculiar CNS species ratio and a low occurrence and diversity of AR transferable genes than found in other studies, as a probable consequence of production only with meat from animals raised in small farms with extensive rearing systems in which antibiotic usage is infrequent.