CC5 MRSA isolates from goats and the farm environment are phylogenetically linked to isolates recovered from human...

Despite MRSA's zoonotic nature, studies demonstrating the phylogenetic relatedness of animal isolates to other sources, including human clinical isolates, are scarce, especially in the Middle East.

We conducted whole genome sequencing (WGS) and phylogenetic analyses of clonal complex (CC) 5 MRSA isolates recovered from goats and their farm environments in Saudi Arabia and isolates recovered from other sources worldwide.

MRSA isolates belonging to sequence type (ST) 6 recovered from goat nasal swabs and farm soil were phylogenetically related to MRSA isolates recovered from patients in Germany, Italy and the USA. Another isolate (ST5) from the goats' milk was phylogenetically related to isolates recovered from the same hospital in Italy as the isolates belonging to ST6. The ST5 isolates from the goat's nasal swab and drinking water were closely related to an MRSA isolate recovered from cheese in Austria and from patients in the USA. We found that there was a strong to moderate link of transmission of isolates belonging to CC5 from the USA to Saudi Arabia (ST6 Posterior Probability (PP) = 0.975, Bayes Factor (BF) = 179 and ST5 PP = 0.409, BF = 7). In addition, we found a moderate link of transmission from Germany (ST6 PP = 0.679, BF = 9) and Italy (ST6 PP = 0.489 BF = 4 and ST5 PP = 0.593 BF = 16). Although only seven MRSA isolates were detected, their close phylogenetic relatedness to human clinical isolates supports potential epidemiological significance and warrants further investigations.

MRSA isolates recovered from goats were phylogenetically related to isolates known to cause infections in humans in the USA and Europe.