In vitro assessment of properties associated with the survival through the gastro-intestinal tract of staphylococci isolated from traditional sausage fermentation

Thirteen Staphylococcus sp. strains, previously isolated from spontaneous sausage fermentation, were in vitro examined for properties associated with their ability to survive through the gastro-intestinal tract. None of the strains were able to survive exposure to pH 1 or pH 2, while for most of them, a population reduction, ranging from 77.3% to 99.0% and a surviving population from 1.7×108 to 9.0×106 was observed after exposure to pH 3. None of the strains exhibited bile salt hydrolase activity or production of antimicrobial compounds, while all of them were resistant to pancreatin. Only S. cohnii cohnii LQC 5112 was found to be α-haemolytic, seven other strains were β-haemolytic and the rest γ-haemolytic. All strains were sensitive to erythromycin, ampicillin (but S. intermedius LQC 5023) and chloramphenicol while most of them were sensitive to tetracycline. On the other hand, most of the strains were resistant to novobiocin. Furthermore, their aptitude, not only to withstand, but to proliferate in the presence of bile salts, as well, even at an acidic environment and their ability to adhere to stainless-steel plates, indicate the need for an in vivo study.