Equipment contact surfaces as sources of Staphylococcus carrying enterotoxin-encoding genes in goat milk dairy plants

Abstract

Potential contamination sources and the enterotoxigenic profiling of Staphylococcus isolates were investigated in four goat dairy plants. Samples (n = 160) were collected from different processing points in five samplings. Staphylococcus spp. isolates were confirmed by polymerase chain reaction and genotyped using repetitive extragenic palindromic PCR (Rep-PCR). Classical (sea, seb, sec, sed) and novel (seg, seh, sei) staphylococcal enterotoxin-encoding genes were detected by PCR. seb, sec, see and sei were identified in isolates originated from raw and pasteurised milk, pre- and post-pasteurisation tanks and wall surfaces. SE-harbouring isolates were mostly identified as non-aureus staphylococci. Genotypic profiles and contamination levels indicate that the packaging machine is a critical point for staphylococcal contamination. Equipment surfaces are important contamination sources to pasteurised milk considering the indistinguishable genotypic patterns of isolates from pre- and post-pasteurisation points. Cleaning and disinfection of milk contact surfaces should be revisited to warrant quality and safety of goat milk.