Abstract
ABSTRACT Bovine clinical mastitis caused by Staphylococcus spp. is a serious and widespread disease in the world of dairy farming. Antimicrobial therapy is of fundamental importance in the prevention and treatment of infectious mastitis, but the indiscriminate use of antimicrobials acts as a determining factor for the spread of the disease. The present study evaluated the resistance profiles of 57 Staphylococcus spp. isolated from bovine clinical mastitis to beta-lactams and gentamicin, relating characteristics of phenotype (in vitro susceptibility tests) and genotype (detection and expression of genes encoding resistance - mecA, mecALGA251, blaZ, femA, femB, and aacA-aphD - using PCR and RT-PCR, respectively). One or more genes coding for resistance to different antimicrobials were detected in 50 Staphylococcus spp. isolates. The femA and femB genes were the most frequent (75.4% for both). The observed expression of the genes was as follows: blaZ (60%), femA (39.5%), aacA-aphD (50%), femB (32.6%), mecA (8.3%), and mecALGA251 (0%). Considering the relevance of the genus Staphylococcus to bovine mastitis, this study aimed to elucidate aspects regarding the genotypic and phenotypic profiles of these microorganisms so as to contribute to the development of effective strategies for mastitis control.
Highlights
Mastitis is an inflammatory process of the mammary gland that interferes directly in milk production and is extremely important for dairy farming
The present study evaluated the resistance profiles of 57 Staphylococcus spp. isolated from bovine clinical mastitis to beta-lactams and gentamicin, relating characteristics of phenotype and genotype
High levels of sensitivity were observed in relation to oxacillin and gentamicin, 93% and 91.2%, respectively
Summary
Mastitis is an inflammatory process of the mammary gland that interferes directly in milk production and is extremely important for dairy farming. The control of mastitis has great importance and should be based on therapeutic and preventive measures. Drug therapy assists the animal's defenses in eliminating the invading agent. Microorganisms often seek to nullify the defense response of the host using the most diverse resistance mechanisms, which have been the targets of extensive studies (Ceniti et al, 2017). Bacterial resistance is related to the existence of different biochemical mechanisms that act to prevent the action of the drugs. Phenotypic and genotypic diagnostic methods for the evaluation of the Staphylococcus spp. resistance profile have been widely used, especially when considering herds of cattle and the possibility of multiresistant pathogens transfer to other animals and humans (Cuny et al, 2011; García-Alvarez et al 2011; Boireau et al 2018)
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