Characterization and molecular epidemiology of strains resistant to beta-lactams isolated from the milk of cows diagnosed with subclinical mastitis.

BACKGROUND AND AIM

The term ESKAPE, recognized by the WHO, is an acronym, which refers to the pathogens , , , , , and spp., which is extremely virulent and multidrug-resistant. Although the term is used to designate nosocomial pathogens, in a milking environment, strains of Methicillin-resistant have been isolated from cattle diagnosed with clinical and subclinical mastitis. Resistant strains may be involved in the transfer of genes conferring resistance to beta-lactam antimicrobials among the species of microorganisms related to mastitis etiology. This study aimed to trace the phenotypic and genotypic profiles of susceptibility to beta-lactams in isolated from milk of cattle diagnosed with subclinical mastitis obtained from different rural properties located in the North of Minas Gerais State, Brazil.

MATERIALS AND METHODS

Sixteen microorganisms previously identified as isolated from milk of cattle diagnosed with subclinical mastitis were submitted to matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF), mass spectrometry, and polymerase chain reaction (PCR) analysis for microbial species confirmation. The beta-lactams antimicrobial phenotypic resistance profile was investigated by disk diffusion method. PCR methods were also performed to investigate the genotypic beta-lactams resistance profile. For this purpose, , A, , , and genes were screened among isolates. The genetic diversity of by fingerprint random amplified polymorphic DNA (RAPD)-PCR was also performed in this study.

RESULTS

All isolates showed phenotypic resistance to at least three beta-lactams, among which was meropenem. None of the isolates tested positive for the genes , , and ; however, the presence of the genes and A was detected among the isolates. The fingerprint analysis divided isolates into two distinct groups and 15 different subgroups. Despite the presence of clonality among the isolates, the PCR-RAPD analysis unveiled a heterogeneous profile with genetic diversity among the isolates.

CONCLUSION

In this study, we identified beta-lactams resistant strains isolated from the milk of cows diagnosed with subclinical mastitis. The beta-lactams resistance was investigated using a phenotypic and genotypic approach. We believe that molecular epidemiology, improved knowledge, and genetic basis of resistance to beta-lactams might assist in asserting guidelines for better management practices of dealing with subclinical mastitis and mapping of origin of resistant pathogens in the studied Brazilian area.