The aim of this study was to determine the potential presence of the airborne Listeria spp. and its correlation with the aerobic mesophilic bacteria and Listeria carcass contamination in three red meat slaughtering and three processing plants. Airborne L. seeligeri and L. innocua were determined in 5.06%, (8/158) air samples taken on the locations characteristic for aerosol generating and in a chilly environment. The positive airborne samples of Listeria spp. were in an insignificant (P ) 0.05) relation with the highest airborne bacteria counts. On the carcass, only 0.69% positive case (1/144) of L. innocua was determined, presumably owing to the low airborne Listeria counts and its unpredictable settling rates. In addition, insignificant (P ) 0.05) influences of air moisture and airflow on the airborne Listeria were found. Nevertheles, the methods currently used to determine the airborne Listeria and its relationships to aerosol viable mesophilic bacteria and carcass contamination need to be reconsidered in future investigations.
During routine microbiological examination of milk samples from dairy cows without clinical signs of mastitis, samples of 231 dairy cows from 12 herds were investigated for the presence of coagulase-negative staphylococci (CNS). The predominant species, S. chromogenes and S. haemolyticus, were further characterized by antibiotic susceptibility testing and by pulsed-field gel electrophoresis (PFGE). Considerable resistance to ampicillin and penicillin was observed in both species. Isolates with identical or highly similar PFGE profiles were detected at the herd level despite a marked heterogeneity seen for both species. On the basis of somatic cell count, absence of clinical signs of inflammation and heterogeneity of genotypes, we assume that CNS isolated in this study could not be considered as important causative agents of the bovine mammary gland inflammation.
Epidemiological studies on Mycobacterium avium are requisite for revealing infection sources and disease transmission. They are based upon genotyping methods like RFLP and MIRU-VNTR. In our study, MIRU-VNTR typing was applied to 121 previously RFLP typed M. avium field isolates to compare the discriminatory power of both methods. The applicability of MIRU-VNTR typing was studied for isolates from a limited geographic area, namely 41 M. avium subsp. avium and 80 M. avium subsp. hominissuis isolates. Among the former, exhibiting 12 IS901 RFLP types, five MIRU-VNTR types were found with discriminatory index (DI) of 0.716. Among the latter, exhibiting 56 IS1245 RFLP types, 18 MIRU-VNTR types were found with DI of 0.866. Concomitant use of both methods increased DI to 0.981 and 0.995, respectively. MIRU-VNTR typing employing the selected markers provided discernible discrimination among M. avium subsp. hominissuis isolates, but more discriminative markers are needed for M. avium subsp. avium isolates.