Multiple correspondence analysis and random amplified polymorphic DNA molecular typing to assess the sources of Staphylococcus aureus contamination in alheira production lines.
Sources and tracing of Staphylococcus aureus in alheira (garlic sausage) production were evaluated by multifactorial correspondence analysis (MCA) of occurrence data and a random amplified polymorphic DNA (RAPD) on S. aureus isolates. Samples from four production lines, four different production batches, and 14 different sampling sites (including raw material, different contact surfaces, and several stages of alheira manufacturing) were analyzed at four sampling times. From the 896 microbial analyses completed, a collection of 170 S. aureus isolates was obtained. Although analysis of the occurrence data alone was not elucidative enough, MCA and RAPD-PCR were able to assess the sources of contamination and to trace the spread of this microorganism along the production lines. MCA results indicated that the presence of S. aureus in alheira was related to its presence in the intermediate manufacturing stages after heat treatment but before stuffing in the casings. It was also possible to associate a cross-contamination path related to handler procedures. RAPD-PCR typing in accordance to MCA results confirmed the cross-contamination path between the raw material and casings and the role of handlers as an important cross-contamination vehicle.
Esteves
A
A
Center of Studies in Animal and Veterinary Science (CECAV), University of Trás-os Montes e Alto Douro (UTAD), 5000-911, Vila Real, Portugal. alexe@utad.pt
Patarata
L
L
Aymerich
T
T
Garriga
M
M
Martins
C
C
D000818:Animals; D015169:Colony Count, Microbial; D005506:Food Contamination / Q000032:analysis*; D005511:Food Handling / Q000379:methods* / Q000592:standards; D005516:Food Microbiology; D005525:Food-Processing Industry / Q000379:methods* / Q000592:standards; D006801:Humans; D006920:Hygiene; D007422:Intestines / Q000382:microbiology; D008461:Meat Products / Q000382:microbiology*; D019105:Random Amplified Polymorphic DNA Technique; D013211:Staphylococcus aureus / Q000145:classification / Q000302:isolation & purification*; D013552:Swine