Clonal Dynamics of Nasal Staphylococcus aureus and Staphylococcus pseudintermedius in Dog-Owning Household Members. Detection of MSSA ST398

Abstract

The objective of this study was to investigate the dynamics of nasal carriage by Staphylococcus aureus (SA) and Staphylococcus pseudintermedius (SP) among healthy dog-owning household members involved in 7 previous index cases of suspected anthropozoonotic (n = 4) and zoonotic (n = 3) interspecies transmission [4 direct cases, identical SA (n = 3) or SP (n = 1) in owner and dog; three indirect, SP in owner (n = 2) or SA in dog (n = 1)]. Co-carriage with methicillin-resistant coagulase-negative staphylococci (MRCoNS) was also evaluated. Sixteen owners and 10 dogs were sampled once every three months for one year. In total, 50 SA and 31 SP were analysed by MLST, and SA also by spa typing. All isolates were subjected to ApaI/SmaI-PFGE and antimicrobial resistance and virulence profiles were determined. All index owners were persistent SA carriers in all direct-anthropozoonotic transmission cases, while only one dog was persistent SA carrier. Owner and dog exhibited a persistent SP carriage status in the direct-zoonotic transmission case. SP was maintained in the index human over time in one indirect-zoonotic transmission case. Only one SP was methicillin-resistant. SA belonged to genetic backgrounds of MRSA pandemic clones: CC45, CC121, CC30, CC5 and CC398. Three individuals carried a MSSA t1451-ST398 clone with the erm(T)-cadD/cadX resistance genes. SA or SP were persistently detected in the nasal cavity of 7 (43.8%) and 2 (12.5%) owners, and in one and 2 dogs, respectively. SA was recovered as the single species in 10 owners and in one dog; SP in 3 owners and 4 dogs; and both bacterial species in one owner and 4 dogs. Co-carriage of SA or SP with MRCoNS isolates was common (30.7%). This is the first study on the dynamics of nasal carriage of SA and SP in healthy pet-owning household members. Dog-contact may play a role in the staphylococcal species distribution of in-contact individuals.

Impact of systemic antimicrobial therapy on mucosal staphylococci in a population of dogs in Northwest England

“…Dogs from multi‐dog households were less likely to be positive for mucosal MRS in this study. This finding was unexpected, because sharing of staphylococci, including MRSP, has been reported between in‐contact individuals and pets, particularly in multi‐dog households . Further, females were more likely to carry MDR isolates than males, a finding that disagrees with previous results for MRS .…”

“…Similar risk factors have been reported or proposed for MR S. aureus (MRSA) and MR coagulase negative staphylococci (MR‐CoNS) carriage in humans; the MR‐CoNS population prevalence in healthy dogs is reported to be up to 42% . Carriage may lead to transfer of staphylococci between individuals or to the environment, with long‐term persistence being reported in both circumstances …”

“…Staphylococcus pseudintermedius has been isolated from up to 87.4% and S. aureus from up to 14% of healthy dogs . Repeated sampling is likely to have yielded a high prevalence of staphylococci in this study; in particular S. pseudintermedius carriage in dogs has been reported to be diverse and changing over time and could be missed with cross‐sectional sampling. Moreover, the majority of enrolled dogs were diagnosed with pyoderma, which may have increased detection of mucosal staphylococci, and in particular, S. pseudintermedius .…”

Genotypic and Phenotypic Markers of Livestock-Associated Methicillin-Resistant Staphylococcus aureus CC9 in Humans

“…We did not identify MRSA ST398 (belonging to CC398) in this study, although several cases of ST398 infection in hospitalized patients have been reported in Hong Kong and China (21,22). In recent years, much attention has been focused on the role of pet animals as reservoirs of antimicrobial-resistant bacteria and on the potential transfer of resistance genes from pets to humans (23)(24)(25). A monitoring study of members of dog-owning households in Spain reported cocarriage of S. aureus ST398 in owners and dogs (23), and another investigation in Canada revealed a high prevalence of concurrent MRSA colonization, as well as identifying indistinguishable strains in humans and pet dogs and cats in the same household, suggesting that interspecies transmission of S. aureus and MRSA is possible (24).…”

“…In recent years, much attention has been focused on the role of pet animals as reservoirs of antimicrobial-resistant bacteria and on the potential transfer of resistance genes from pets to humans (23)(24)(25). A monitoring study of members of dog-owning households in Spain reported cocarriage of S. aureus ST398 in owners and dogs (23), and another investigation in Canada revealed a high prevalence of concurrent MRSA colonization, as well as identifying indistinguishable strains in humans and pet dogs and cats in the same household, suggesting that interspecies transmission of S. aureus and MRSA is possible (24). A recent review concluded that available data on MRSA transmission between pet animals and humans are limited and that the public health impact of such transmission needs to be subjected to more detailed epidemiological studies (25).…”