| Congresso Brasileiro de Microbiologia 2023 | Resumo: 589-1 | ||||
Resumo:Streptococcus agalactiae (GBS) and Staphylococcus aureus are considered leading agents of contagious bovine mastitis in low-and middle-income countries (LMIC) ranked as top-milk producers globally, like Brazil. The lack of national mastitis management programs in those countries leads to economic losses to the dairy industry and the unnecessary use of broad-spectrum antibiotics. The rise of antimicrobial resistance (AMR) is a worldwide concern and the overuse of antimicrobial agents in the veterinary setting fosters this
phenomenon. Thus, surveillance of AMR in GBS and S. aureus causing bovine mastitis is needed to inform public health risks and control strategies. In this study, short-read whole genome sequencing was performed to 156 GBS and 135 Staphylococcus aureus strains and AMR genes were identified from the genomes using the SRST2 program. GBS strains were recovered from milk samples from 33 different herds in Rio de Janeiro between 1987 and 2021, and S. aureus strains were recovered from milk samples from 25 different herds in Rio de Janeiro between 1990 and 2019. Species identification was performed by MALDI-TOF MS. The AMR genes found among the GBS strains were: tet (tetO n=61, 39%; tetM n=37,24%), erm (ermB n=41, 26%; ermA n=20, 13%), ant(6)-Ia (n=18, 11%) and lnuC (n=1, 1%). Among all GBS strains, 12% (n=19) were multidrug resistant (resistance to three or more different antimicrobial classes). The major multidrug resistance profiles found in GBS were the following combinations of AMR genes: ant(6)-Ia + ermA + ermB + tetO (n=15; 80%) and ant(6)-Ia + ermA + ermB + tetM + tetO (n=2; 10%). The AMR genes found among the S. aureus strains were: norA (n=86, 64%), tet (tet38 n=85, 63%; tetK n=19, 14%; tetL n=2, 1%), blaZ (n=79, 59%), fosB1 (n=44, 32%), ermC (n=4, 3%), msrA (n=2, 1%) and mecA (n=1, <1%). Among all the S. aureus strains, 71% (n=96) were multidrug resistant. The main multidrug resistance profiles found in S. aureus were the following: blaZ + norA + tet38 (n=34, 35%) and blaZ + norA + fosB1 + tet38 (n=37, 38%). Over the years, AMR rates increased in GBS and S. aureus strains. GBS strains were resistant to tetracyclines (tet genes), macrolides (ermA and ermB), aminoglycosides (ant6-Ia), and lincosamides (lnuC, ermA and ermB). On the other hand, S. aureus strains were resistant to fluoroquinolones (norA), tetracyclines (tet38) and penicillins (blaZ). Furthermore, one S. aureus strain carried the mecA gene, which encodes an alternative penicillin-binding protein (PBP2a) that confers high-level resistance to methicillin (methicillin-resistant S. aureus, MRSA). In this study, most GBS and S. aureus strains carried AMR genes that confer resistance to antimicrobial agents commonly used for treatment (human and veterinary medicine settings) and growth promotion in Brazil, highlighting the detection of MRSA and clindamycin-resistant GBS strains which are recognized as global public health threats. The antimicrobial overuse in veterinary fosters the clonal spread of drug-resistant strains that circulates among cattle and
can be transmitted to and infect humans. Thus long-term surveillance of drug-resistant GBS and S. aureus strains is needed to guide local farmers and policymakers on CBM control practices, including antibiotic choice. Palavras-chave: Streptococcus agalactiae, GBS, Staphylococcus aureus, bovine mastitis, antimicrobial resistance genes Agência de fomento:Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, CAPES | |||||