Antibiotic Resistance and Molecular Analysis of Staphylococcus aureus Isolated from Cow's Milk and Dairy Products in Northeast Brazil

Abstract

This work aimed to assess the clonal distribution among 94 strains of Staphylococcus aureus isolated from cow's milk, raw cheese, and a milking machine in 12 dairy farms in northeast Brazil, by analyzing different typing methods and detecting resistance and toxigenic profiles. For the first time, isolates of this region were assessed simultaneously by the polymorphism of the 3'-end coa gene and 16S-23S rDNA, pulsed-field gel electrophoresis, antibiotic resistance phenotyping, and toxigenic arsenal. Although pulsed-field gel electrophoresis patterns showed a wider variation (discriminatory index 0.83) than the PCR-based methods, the internal transcribed spacer-PCR proved to be a useful and inexpensive procedure for conducting epidemiological surveys of S. aureus on a regional scale. Each dairy farm had its own resistance profile, and in two herds, 63% of the strains were multiresistant, probably due to the indiscriminate use of antibiotics in bovine mastitis treatment. No methicillin-resistant S. aureus strains were detected in this study; however, 93.6% of S. aureus strains harbored variable profiles of staphylococcal enterotoxin genes seg, seh, sei, and sej. Transcriptional analysis revealed that 53.3% of staphylococcal enterotoxin genes actually transcribed, pointing out the food poisoning risk of these dairy products to consumers in the region. Based on the detection of the most prevalent clones in a herd or region, appropriate antibiotic therapy and specific immunization can be used for the treatment and control of staphylococcal mastitis.

Comparison of Virulence Gene Identification, Ribosomal Spacer PCR, and Pulsed-Field Gel Electrophoresis for Typing of Staphylococcus aureus Strains Isolated from Cases of Subclinical Bovine Mastitis in the United States

“…These specific enterotoxin genes were not tested for in this study due to a lack of association with the previously described GTB (9). Studies from other parts of the world have identified different prevalences of enterotoxin genes, suggesting possible geographic differences (26,27). Because of these differences, typing isolates by virulence gene identification in combination with RS-PCR likely does not represent a universally applicable rapid method for identifying contagious and pathogenic S. aureus strains.…”

“…The discriminatory power of PFGE for typing of S. aureus strains has been previously described (27,29,30) and has been measured in a range from 0.83 to 0.8887. Comparing several strain-typing methods to characterize S. aureus isolates of bovine origin, PFGE had the highest discriminatory power, followed by multilocus sequence typing (MLST), multilocus variable-number tandem-repeat analysis (MLVA), and then spa typing (29).…”

Molecular Divergence of Staphylococcus Aureus Isolated from Pork Byproducts Based on Coagulase Gene Polymorphism and The Presence of Enterotoxigenic genes

“…The present study emphasizes the genotypic variation among different S.aureus isolates discussed in many previous reports. Pulsed-field gel electrophoresis patterns showed a wider variety (discriminatory index 0.83) among 94 strains of S. aureus isolated from cow's milk, raw cheese, and a milking machine in 12 dairy farms in northeast Brazil [20]. Another study in Iran; fifty eight S. aureus isolates were recovered from milk samples of cows with clinical and subclinical mastitis were analyzed using RFLP of coa gene with restriction endonuclease HaeIII, resulting in nine patterns [21].…”

Antimicrobial profile of multidrug-resistant Staphylococcus spp. isolated from bovine mastitis cases in the northwest region of Paran State, Brazil

“…The presence of mastitis in dairy cows requires the use of antibiotics to treat the animals. However, the inappropriate use of these drugs over the years allowed the emergence of multi-drug resistant bacteria (Silveira-Filho et al, 2014;Gaze et al, 2008;Thomson et al, 2008;Krause and Hendrick, 2011). This study showed that 27.55% of isolates were antibiotic-resistant among the S. aureus, CoNS, S. dysgalactiae and coagulasepositive/VP-negative Staphylococcus spp.…”