Factors responsible for subclinical mastitis in cows caused by Staphylococcus chromogenes and its susceptibility to antibiotics based on bap, fnbA, eno, mecA, tetK, and ermA genes.
The aim of this study was to recognize selected factors of virulence determining the adhesion of Staphylococcus chromogenes to cows' udder tissues in subclinical mastitis and to evaluate the susceptibility of this pathogen to antibiotics. The subjects of the study were 38 isolates of Staph. chromogenes from 335 samples of milk from cows with subclinical coagulase-negative staphylococci mastitis. Somatic cell count ranged between 216,000 and 568,000/mL of milk (average 356,000/mL of milk). We confirmed the ability to produce slime in 24 isolates (63.2%), and the ability to produce protease in 29 isolates (76.3%). In each slime-producing isolate, the bap gene was not found, and the fnbA and eno genes were not detected. In vitro tests showed that ceftiofur had the highest effectiveness against Staph. chromogenes (89.5% of susceptible isolates). Minimum inhibitory concentrations ranged from 0.06 to 2µg/mL for susceptible isolates. The minimum concentrations required to inhibit growth of 90 and 50% of the isolates for ceftiofur were at or below the cutoffs recommended by the Clinical and Laboratory Standards Institute (2 and 0.06µg/mL, respectively). A significant percentage of the isolates were susceptible to other β-lactam antibiotics: amoxicillin with clavulanic acid (84.2%) and ampicillin (81.6%). The lowest effectiveness among β-lactams was for penicillin (73.7% of susceptible isolates), and the minimum inhibitory concentration for penicillin ranged from <0.06 to 8µg/mL. None of the examined isolates had the mecA gene, but β-lactamase was detected in 4 isolates (10.5%). Erythromycin and oxytetracycline exhibited the lowest activity against Staph. chromogenes (71.1 and 63.2% of susceptible isolates, respectively). The genes tetK (6 isolates) and ermA (1 isolate) were also detected.
Department and Clinic of Animal Reproduction, Faculty of Veterinary Medicine, University of Life Sciences, Lublin 20-612, Poland. Electronic address: mariolabochniarz@interia.pl.
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Bochniarz
Department of Epizootiology and Clinic of Infectious Diseases, Faculty of Veterinary Medicine, University of Life Sciences, Lublin 20-612, Poland.
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Adaszek
Department of Epizootiology and Clinic of Infectious Diseases, Faculty of Veterinary Medicine, University of Life Sciences, Lublin 20-612, Poland.
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B
Dzięgiel
Institute of Biological Bases of Animal Diseases Sub-Department of Veterinary Prevention and Avian Diseases, University of Life Sciences, Lublin 20-612, Poland.
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A
Nowaczek
Department and Clinic of Animal Reproduction, Faculty of Veterinary Medicine, University of Life Sciences, Lublin 20-612, Poland.
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Wawron
Department and Clinic of Animal Reproduction, Faculty of Veterinary Medicine, University of Life Sciences, Lublin 20-612, Poland.
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R
Dąbrowski
Department and Clinic of Animal Reproduction, Faculty of Veterinary Medicine, University of Life Sciences, Lublin 20-612, Poland.
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M
Szczubiał
Department of Epizootiology and Clinic of Infectious Diseases, Faculty of Veterinary Medicine, University of Life Sciences, Lublin 20-612, Poland.
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Winiarczyk
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002417:Cattle; D005260:Female; D008413:Mastitis; D008414:Mastitis, Bovine; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D008892:Milk / Q000187:drug effects; D013203:Staphylococcal Infections / Q000662:veterinary; D013210:Staphylococcus / Q000187:drug effects
D000900:Anti-Bacterial Agents
Staphylococcus chromogenes; coagulase-negative staphylococci; subclinical mastitis