Toxigenic Staphylococcus aureus lineage belonging to Sequence Type (CC)1 with ability to acquire antimicrobials resistance, as the main colonizer of Argentinean dairy cows

GONZÁLEZ M JOSÉ ; BLASKO ENRIQUE G; PERILLO CILL FACUNDO ; BARCUDI DANILO ; PORPORATO CARINA ; BONETTO CESAR ; BOCCO JOSÉ LUIS; SOLA CLAUDIA

MENDOZA

Congreso; LVIII Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology Research; 2022

SAIB

S. aureus colonizes and infects both humans and animals. It has the capacity to acquire virulence genes and antimicrobials resistance (AR), such as methicillin-resistance (MRSA) and the potential for spread in hospitals (HA), community (CA), livestock (LA) and in the animal–human interface, through clones with increased virulence, transmissibility and/or AR (high-risk clones, HRCs). S. aureus ST1/Clonal Complex (CC) 1 is associated with human infections and also is one of the major LA- lineages related to pigs and bovines in some European countries. There are not information in Argentina about the prevalence and molecular epidemiology of colonization in cattle.The aim of this study was to investigate the prevalence of carriage, antimicrobial resistance profile and molecular types of S. aureus in bovines from dairy farms in a Humid Pampa region, the main agricultural and cattle area of Argentina, as a possible reservoir of HRCs. A prospective cross-sectional study was performed in four dairy farms from the area of Villa María city, Córdoba, Dec. 2019. Surveillance cultures for S. aureus from nasal (NS) and rectal (RS) swabs were obtained from 439 cows, in 56 of them milk samples (quarter-milk pool sample /QM) were also collected. A colonized cow had at least one positive sample for S. aureus. The AR was determined by diffusion/Vitek2, CLSI2019 and the presence of mecA/C, ermA/C/B/T and virulence genes by PCR. All isolates were genetically characterized by PFGE, spa typing and MLST.Of the total positive samples, 77.5% (n: 55), 18.3% (n: 13) and 9.9% (n: 7) were from NS, QM and RS respectively. One lineage (CC) colonized 73.3% of the bovines positive (52/71), all in NS and/or RS: (47 NS, 4 NS and RS, 1 RS: 56 strains): ST1-PFGE-FF/t2207 seh+, bsa+, lukED+, cna+, sek+, with a major subtype FF11 (81%, n: 42/52) that also co-colonized 4 bovines in NS and RS. These strains showed a genetic feature typical of animal adaptation such as the absence of Immune evasion cluster (IEC) genes sak and scn. Other four CCs were identified: 15.5% ST97-DD/t2297 (n: 11, 9 QM, 2 RS), 7.0% ST133-DDO/t17747 (n: 5, 4 QM and 1 RS) and 1.4% (all NS): ST398-/t1451, ST45-AA/t026 and ST8-USA300/t024. All were MSSA, 4/75 (5.3%) R to Erythromycin and Clindamycin: 2 MLSBc (ST1 ermC+) and 2 MLSBi (ST398 ermT+ and ST8 ermC+), 1.3% R to Rifampicin (ST1) and 1.3% R to Ciprofloxacin (ST45).In conclusion, in Argentina, bovines are reservoir of a toxigenic S aureus HRC belonging to CC1, with ability to acquire AR, related to humans and adapted to animals, along with other minor CCs some of these related to human (CC45 and CC8) and others associated with cattle (CC97, CC133 and CC398). These data are important for the control of HRCs and AR transmission, and support the implementation of farm-level strategies to prevent spill-over.