Bovine Coagulase·negative Staphylococci: Biochemistry and Polymerase Chain Reaction

Hum mel, R., G . L e h man n : Bovine coagulase-negative Staphylococci: Biochemistry and Polymerase Chain Reaction. Acta vet. Brno, 63,1994: 133-139. Staphylococcus (S.) simulans, S. chromogenes, and S. epidermidis were the species of coagulase-negative staphylococci (CNS) most frequently involved in subclinical mastitits of dairy cattle. The same biochemical features characterized the successive isolates of a particular chronically infected udder quarter. Occurrence rate of the various species differed between the herds examined. In cases of clinical mastitis of cows S. xylosus, S. simulans, S. haemolyticus, and S. chromogenes predominated. A comparison between strains of the particular CNS species from infections in man and cattle did not show host attributable biochemical features or profiles obtained by polymerase chain reaction using arbitrary primers (AP-PCR). Bovine mastitis, Coagulase-negative staphylococci, biochemical features, polymerase chain reaction Coagulase-negative staphylococci (CNS) can by frequently isolated from milk samples of dairy cows, often in association with subclinical mastitis (T i m m s et al. 1987; H arm 0 n and Lan g I 0 i s 1989; Watt s et al. 1989; Davidson et al. 1992; Matthews et al. 1992; Todhunter et al. 1993). For differentiation between species of CNS several approaches have been supposed. Typing schemes primarily based on panels of biochemical tests have often been applied in tandem with other methods including composition of cell wall, isoenzyme pattern, polymorphism of whole cell protein and penicillin binding protein, pattern of rRNA gene and of endonuclease cleaved DNA, polymerase chain reaction using arbitrary primers (AP-PCR). By AP-PCR Welsh and McClelland (1990) obtained species specific patterns of AP-PCR products. Moreover, Staphylococcus (S.) haemolyticus of human and non-human primate origin produced different AP-PCR patterns related to their ecological origin and supposedly to host specifity of strains. The purpose of this work is to study (1) involvement of the various CNS species in udder infections of cows and (2) comparison between strains within the particular CNS species originating from man and cattle by means of AP-PCR. Materials and Methods Bacterial strains The CNS examined in this study originated from cases of clinical mastitis (54 strains) and of subclinical mastitits (57 strains) in cattle. For comparison, 8 strains from infections in man were included in these studies. Of the strains from bovine clinical mastitis 41 were isolated from udder secretions in 39 dairy herds submitted for bacteriological examination to the regional veterinary laboratory. An additional 13 strains originated from Belgium. The 57 strains from subclinical mastitis were selected in five large herds of cattle (Table 1) with 300 to 500 cows each. An infection of the mammary gland means isolation of CNS in pure culture together with an elevated total cell count (>300 000 cells/ml milk). Sampling of udder secretions was carried out before and after milking. Repeated isolates from a particular udder quarter possessed of the same biochemical features were considered a single strain. The 57 strains represented a total of 580 isolates. All of the herds practised post milking teat dipping but only two of them (herds Np and Lu) applied a proper hygiene at milking. There was an occasional history of Streptococcus agalacriae in these herds and the infected cows were removed for slaughter. In herd Np quarter milk samples from 463 cows at freshening were investigated for the presence of CNS infections. 21 cows with 29 chronically CNS infected quarters in herd Np were resampled monthly or bimonthly to the next freshening. The 29 strains represented a total of 502 isolates. In herds Mo and Zi, respectively, 7 out of 197 and 3 out of 293 cows could be found chronically infected. Three consecutive samplings were performed and a total of 42 isolates gathered. Herds Ka and Lu have been sampled only once.