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Comparative analysis of Staphylococcus aureus strains by molecular microbiology methods
34-39Views:665Staphylococcus aureus is a very important pathogen for dairy farms and milk processing plants. Subclinical mastitis is often caused by this species, and it can contaminate bulk tank milk when milking cows are suffering from mastitis. Additionally, thermostable enterotoxins (SE) produced by some types of this bacterium can cause food poisoning.
The aim of our research was to examine the number of S. aureus in bulk tank milk in two dairy farms and the enterotoxin-producing ability, genetic relation (pulsotype) and antibiotic resistance of S. aureus strains from different sources (bulk tank milk, udder quarter milk and environment).
The results show that the mean number of S. aureus of bulk tank milk of two farms significantly differed (P<0.05). Fourteen isolates were selected for further molecular genetic studies (five isolates were from bulk tank milk and nine isolates were from udder quarter milk). S. aureus was not recovered from the environmental samples. Three of the fourteen isolates (21.4%) tested by multiplex PCR were positive for SE genes. Two isolates carried one gene (seb) and one isolate carried two genes (seg and sei). The fourteen strains were classified into three pulsotypes and two subtypes at 86% similarity level. Isolates from bulk tank milk (n=5), were divided into 2 pulsotypes (A, C) and one subtype (C1). The isolates from udder quarter milk (n=9) belonged to three different pulsotypes (A, B, C) and two subtypes (A1, C1). The distribution of pulsotypes in the present study revealed genetic relationship between S. aureus isolated from udder quarter milk and bulk tank milk. This could be explained by the fact that in farms with a high number of infected cows, these cows could represent the main source of contamination. The results of the antibiotic resistance investigations show, that all strains were susceptible to methicillin, cefoxitin, lincomycin, tetracycline, erythromycin and sulfamethoxazole/trimethoprim. Thirteen out of fourteen strains were resistant to penicillin (A and C pulsotypes, A1 and C1 subtypes) and just one isolate was susceptible (B pulsotype) to all antibiotics tested. -
Identification of Hucul mare families by mtDNA markers
75-79Views:735Hundred animal species have disappeared during the last century. By this time, approximately one-third of domestic animals have been in the endangered category. Hucul horses are also in this category; furthermore saving the genetic diversity beside the race preservation is an important challenge as well. The number of mares and stallions is only one of the expressive elements of genetic diversity; together with their quality determine the genetic variability of this breed. Beyond that, if an exact breed can originates from more founders, it can be more renewed genetically. Stud book documents these data by registering the mare families and stallions’ genealogical lineage. Molecular genetics, especially mitochondrial DNA analysis can make the precise identification of mare families possible. As a result of these molecular based methods, protection of genetic diversity, as well as breed preservation became more reliable. After the primer designing, the optimal primer pair was chosen which targets a 1092 bp length DNA sequence in the cytochrome b region. After the successful PCR optimalisation, we determined 170 Hucul mares’ sequences. According to our results, the samples compose ten haplotypes, which are much less, than the registered number of mare families in the stud book. Further investigations are needed to reach more representative results, and drawn the further consequences.