Phenotypic and genotypic characterization of Staphylococcus aureus isolates in milk from flocks diagnosed with subclinical mastitis

Abstract

The Staphylococcus aureus is the most common isolated microorganism in ruminant animal species diagnostic with clinical or subclinical mastitis. Dairy herds with these diseases can transfer S. aureus into the milk supply, which can lead to food poisoning in humans. The objective of this study was to evaluate the profile of antimicrobial susceptibility, the presence of femA gene, the genetic relationships among isolates of S. aureus obtained from milk originating from flocks diagnosed with subclinical mastitis in nine rural properties in the northern of Minas Gerais State. To this end, 498 samples of bovine milk tested positive for the California mastitis test (CMT) were subjected to morphological methods and biochemical patterns for microbiological presumptive identification of S. aureus. The PCR test with the genetic marker femA was used to confirm the species S. aureus. All the 26 isolates presumptively identified as S. aureus amplified a fragment of 132 bp corresponding to the femA gene. The profile of antimicrobial susceptibility was performed according to the disk-diffusion methodology and two isolates were susceptible to all the antibiotics tested. The drug multiresistence was found in 80.76% of the isolates. The determination of the genetic profile and the clonal relationship among the isolates was performed by the method of DNA RAPD-PCR polymorphism. The S. aureus isolates were divided into two groups with 26 distinct subgroups. The analysis of RAPD-PCR showed no genetic diversity among them, heterogeneous profile and absence of clonality.

Identification and characterization of methicillin-resistant Staphylococcus spp. isolated from surfaces near patients in an intensive care unit of a hospital in southeastern Brazil

“…The species isolated from the surface samples of this study were all CoNS. The microorganisms identified were S. haemolyticus (11), S. epidermidis (4), S. capitis (2), and S. cohnii (1) ( Table 1).…”

“…A total of 42 colonies from different sampling sites were analyzed using the Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) proteomic identification approach in the AQUACEN laboratory of the Veterinary School of the Federal University of Minas Gerais (UFMG), according to the methodology previously described by Assis et al 14 , using a Microflex TM MALDI-TOF MS device (Bruker Daltonics, USA). Furthermore, the genomic PCR method was used to identify S. aureus at the species level through the detection of the femA marker gene, as described by Xavier et al 11 …”

“…They can be differentiated from S. aureus at the species level through PCR identification of the femA gene (an essential factor for methicillin resistance). This gene encodes a 48-50 kDa protein recognized as a specific factor and is contained in the chromosomes of these pathogens 11 . Thus, the objective of this study was to screen and characterize methicillin-resistant Staphylococcus spp.…”

Caracterização genotípica de Staphylococcus aureus resistentes à meticilina isolados de tetos e leite bovino

“…Os isolados foram previamente identificados por meio da detecção do gene femA, marcador especifico de espécie para S. aureus meticilina resistente, conforme descrito por (Xavier et al, 2017a) e MALDI-TOF MS (Assis et al, 2017) e testados quanto ao perfil de sensibilidade a antibióticos do grupo beta-lactâmicos pelo método disco de difusão conforme protocolo do Clinical and Laboratory Standards Institute (CLSI, 2018). Foram testados os antimicrobianos oxacilina (1µg), cefoxitina (30µg), penicilina (10 µg), amoxicilina (10µg), cefoxitina (30µg) e ampicilina (10µg) da Laborclin.…”

Staphylococcus aureus isolates from bovine subclinical mastitis in central Ethiopia revealed the presence of antimicrobial resistance and resistant genes

“…Therefore, investigation of a wide spectrum of antimicrobial resistance genes of S. aureus isolated from cows with mastitis is crucial not only for bovine mastitis control, but also for public health (Xavier et al, 2017;Kadlec et al, 2019).…”