Antibiotic resistance in Staphylococcus aureus strains isolated from cows with mastitis in eastern Poland and analysis of susceptibility of resistant strains to alternative nonantibiotic agents: lysostaphin, nisin and polymyxin B.

Abstract

The aim of this study was to analyze the resistance of Staphylococcus aureus isolates from bovine mastitis in the eastern part of Poland to a set of 20 antibiotics and three alternative agents: lysostaphin, nisin and polymyxin B. Eighty-six out of 123 examined isolates were susceptible to all 20 tested antibiotics (70%). The highest percentage of resistance was observed in the case of β-lactam antibiotics: amoxicillin (n=22, 17.9%), ampicillin (n=28, 22.8%), penicillin (n=29, 23.6%) and streptomycin (n=13; 10.6%). Twenty-five of the penicillin-resistant strains were found to carry the blaZ gene coding for β-lactamases. Two strains were found to be mecA positive and a few strains were classified as multidrug resistant (MDR), one of them was simultaneously resistant to six antibiotics. All strains, resistant to at least one antibiotic (n=37) and two control strains, were susceptible to lysostaphin with MIC values of 0.008-0.5 µg/ml (susceptibility breakpoint 32 µg/ml). Twenty-one (54%) isolates were susceptible to nisin. The MIC value of this agent for 17 (44%) strains was 51.2 µg/ml and was not much higher than the susceptibility breakpoint value (32 µg/ml). Polymyxin B was able to inhibit the growth of the strains only at a high concentration (32-128 µg/ml). The presented results confirmed the observed worldwide problem of spreading antibiotic resistance among staphylococci isolated from bovine mastitis; on the other hand, we have indicated a high level of bactericidal activity of nisin and especially lysostaphin.

• Authors: Piotr Szweda, Marta Schielmann, Aneta Frankowska, Barbara Kot, Magdalena Zalewska
• Journal: The Journal of veterinary medical science (J Vet Med Sci) Vol. 76 Issue 3 Pg. 355-62 (Mar 2014) ISSN: 1347-7439 [Electronic] Japan
• PMID: 24212507 (Publication Type: Journal Article)

Chemical References

• DNA Primers
• Nisin
• Lysostaphin
• Polymyxin B

Topics

• Animals
• Cattle
• DNA Primers (genetics)
• Drug Resistance, Bacterial (genetics)
• Female
• Lysostaphin (pharmacology)
• Mastitis (drug therapy, microbiology)
• Microbial Sensitivity Tests (veterinary)
• Nisin (pharmacology)
• Poland
• Polymerase Chain Reaction (veterinary)
• Polymyxin B (pharmacology)
• Staphylococcus aureus (drug effects, genetics)