Impairments of mecA gene detection in bovine Staphylococcus spp.

Abstract

Staphylococcus aureus antimicrobial resistance, especially to beta-lactams, favors treatment failures and its persistence in herd environment. This work aimed to develop a more specific primer for mecA gene detection based on the comparison of the conserved regions from distinct host origins and also investigated the presence of homologue mecALGA251 in bovine strains. A total of 43 Staphylococcus spp. were included in this study, comprising 38 bovine S. aureus, two human and three equine coagulase-negative staphylococci (CNS). Phenotypical methicillin-resistance detection was performed through oxacillin agar-screening and cefoxitin disk-diffusion test. None isolate tested positive for mecALGA251 gene. For mecA gene PCR, new primers were designed based on the sequences of human S. aureus (HE681097) and bovine S. sciuri (AY820253) mecA. The new primers based on the S. aureus mecA sequence amplified fragments of human and equine CNS and the ones based on S. sciuri mecA sequence only yielded fragments for S. aureus bovine strains. Multiples alignments of mecA gene sequences from bovine, human and equine revealed punctual but significant differences in bovine strains that can lead to the mecA gene detection impairment. The observed divergences of mecA gene sequences are not a matter of animal or human origin, it is a specificity of bovine samples.

Characterization of Coagulase-Negative Staphylococci and pheno-genotypic beta lactam resistance evaluation in samples from bovine Intramammary infection

“…They were identified as S. chromogenes (3), S. epidermidis (3), S. hominis (2) and S. hyicus (1), but only 2 S. epidermidis were positive for the mecA and mecRI genes. Another 9 isolates, 6 S. sciuri and 3 S. chromogenes, were also positive for the mecA gene (Murakami et al, 1991) and other 6 S. sciuri were positives for the mecA variant (Melo et al, 2014), but they were susceptible to all antimicrobials. They were also negative for the mecI and mecRI genes.…”

“…Even though the mecA gene was found in 11 strains, only two of them showed resistance to cefoxitin. The mecA variant typical from bovine samples, impossible to detected by routine PCR (Melo et al, 2014), was found in 6 S. sciuri, that were all susceptible to cefoxitin too. Kim et al (2013) made a study explaining the hetero-resistance to the betalactam family of antibiotics in methicillin resistant isolates.…”

“…Genotypic resistance profiles were determined by PCR, targeting genes encoding resistance to beta-lactams, including mec genes: mecA (Murakami et al, 1991), mecA variant (Melo et al, 2014), and mecA1 (pbpD) (Couto et al, 2010); mecI (Lencastre et al, 2002), mecRI (Rosato et al, 2003), and blaZ (Rosato et al, 2003).…”

Characterization of virulence and antibiotic profile and agr typing of Staphylococcus aureus from milk of subclinical mastitis bovine in State of Rio de Janeiro

“…Detection of the mecA gene in isolates of bovine origin with oxacillin resistance phenotype is problematic. Melo et al (2014) detected point mutations in the annealing region of primer, which resulted in design of new primers for the detection of mec gene in isolated bovine (mec bovine). GarciaAlvarez et al (2011) also detected mutations in the gene mec, and described a new allele called mecC, this gene has been found in humans and animals, but until the present date, this allele was not detected in the Americas.…”

Biofilm production and beta-lactamic resistance in Brazilian Staphylococcus aureus isolates from bovine mastitis

“…After overnight incubation at 35 °C, followed by inhibition zone measurement,16, 17 the results were evaluated as per the interpretation criteria following the CLSI standards 15 . PCR was performed for mec A using primers designed by Murakami et al 24 and Melo et al 25 and for bla Z according to Rosato et al 26 (Table 1). …”