Nejeschlebová Ludmila

Potravinarstvo, 2015, 9(1): 154–159.

Potravinarstvo, 2015, 9(1): 166–173.

There were cheeses produced from raw cow’s milk and from mixed milk compared. Mixed milk contained small ruminants’ milk (goat’s and ewe’s milk) and cow’s milk in diff erent proportions. There were technological, physical and health parameters, mineral composition, microbiological indicators and sensory quality evaluated. Cow’s milk, compared to mixed milk, contained markedly lower amounts of fat, protein, casein, total solids, solids non fat, urea and acetone and higher values of lactose, citric acid and free fatty acids and showed signifi cantly lower values of somatic cell count. Mixed milk showed lower (better) results for freezing point depression, markedly higher titration acidity and higher values for Ca, Mg, K, P, Cu, Mn and Zn. The results of microbiological analyses confi rmed good hygienic quality in terms of total count of mesophlic, psychrotrophic and thermoresistant bacteria and coliforms. Negative incidence of L. monocytogenes and mostly negative incidence of S. aureus are important results and confi rmed high quality of raw material for cheese production. None of S. aureus strains were confi rmed as MRSA. The results of sensory evaluation showed no signifi cant diff erences between cheeses originated from cow’s milk and cheeses from mixed milk.

Influence of breed on somatic cell count (SCC) and occurrence of particular species was evaluated. The samples were collected from farms with Holstein (H; 10 farms - 365 cows) breeding and from farms with Czech Fleckvieh (CF; 2 farms – 67 cows). The obtained dataset was statisticaly evaluated by analysis of variance. The occurrence of pathogens was compared between H and CF. The relationship between SCC and incidence of pathogens was determined as well. It is evident that more positive cows were in breed H compared to CF (H 41.6%; CF 26.9%). The most frequent pathogens in H breed were S. aureus(13.7%), S. uberis (9.6%), S. haemolyticus (8.5%), S. agalactiae (6.9%), E. faecalis (2.5%) and E. faecium (0.8%), while only S. uberis (19.4%), S. haemolyticus (6%) and S. aureus (1.5%) were found in CF. SCC results showed the higher SCC in H breed in case of both negative and positive cows as well and significant impact of breed on logSCC (F = 6.4, P = 0.012). The significant effects of bacterial species were confirmed (F = 13.6, P 0.001). Multiple comparison among groups of bacterial species showed significant differences between negative and S. aureus, S. agalactiae, S. uberis (P = 0.012, P 0.001, P 0.001). Differences between negative and other pathogens were not signifiant.

Methicilin rezistentní kmeny Staphylococcus aureus se dělí na základě epidemiologických a genetických charakteristik na nemocniční (hospital-acquired, HA-MRSA), komunitní (community-associated, CA-MRSA) a vázané na chov hospodářských zvířat (livestock associated, LA-MRSA). Podle výsledků Evropského centra pro prevenci a kontrolu onemocnění (ECDC) za rok 2011 byl hlášen výskyt MRSA v humánní populaci v ČR 14,5 % (17. místo ze všech 28 zemí), přičemž v roce 1993 byla incidence MRSA v ČR 6,1 %. Vedle výskytu MRSA se v prostředí prvovýroby mléka často izolují rezistentní kmeny Staphylococcus epidermidis, které jsou schopné přenášet rezistenci nejen uvnitř druhu, ale i mezidruhově. Naše výsledky potvrzuji, že kmeny S. epidermidis byly potvrzeny jako nejčastěji rezistentní uvnitř svého druhu, zatímco S. aureus byl rezistentní uvnitř druhu pouze ve 4,5 %. Toto zjištění představuje vážný problém, neboť koaguláza-negativní stafylokoky se stávají hlavními izolovanými mikroorganismy ve spojení s mastitidním onemocněním