Resumo

SANCHEZ-CEJA, Mónica et al. Use of nisin and chitosan for the inhibition of antibiotic resistant Staphylococcus aureus bovine mastitis-associated. Rev. mex. de cienc. pecuarias [online]. 2018, vol.9, n.4, pp.792-810. ISSN 2448-6698.  https://doi.org/10.22319/rmcp.v9i4.4468.

This study describes the antibiotic resistance patterns of Staphylococcus aureus isolates from cows with mastitis, as well as their in vitro susceptibility to nisin, chitosan and the nisin/chitosan composite. From milk samples obtained from sick cows, 53 S. aureus isolated were identified, the profile of antibiotic resistance was analyzed. The results showed a high frequency of resistance to beta-lactams group, mainly penicillin, dicloxacillin and ampicillin. In addition, multiresistance was detected in some isolates, since they showed tolerance to 3 or 4 different groups of antibiotics, highlighting the isolates AMC-9 (resistant to three groups) and AMC-23 (resistant to four groups). It is also noted that all isolates were susceptible to levofloxacin. On the other hand, the in vitro susceptibility of the isolates to nisin, chitosan and the nisin/chitosan composite was analyzed determining the Minimum Inhibitory Concentration (MIC). The results indicated 100 % of the isolates were susceptible to chitosan and to the nisin/chitosan composite and 47.1 % to nisin. The effect of chitosan and nisin/chitosan composite on the multi-resistant isolates AMC-9 and AMC-23 was bactericidal. These results show the potential of the antimicrobial compounds chitosan, nisin/chitosan to be used as therapeutic agents against bovine mastitis.

Palavras-chave : Staphylococcus aureus; Bovine mastitis; Resistance; Nisin; Chitosan.