Dog ownership is a risk factor for methicillin-resistant Staphylococcus aureus (MRSA) colonisation in humans, a German review and meta-analysis reports.
To get a better understanding of the risk for multidrug-resistant organism (MDROs) colonisation posed by pet ownership, the researchers conducted three separate reviews and meta-analyses of literature on pet ownership and MRSA, third-generation cephalosporin-resistant Enterobacterales (3GCRE) and carbapenem-resistant Enterobacterales (CRE), and vancomycin-resistant Enterococcus (VRE).
The primary outcome was the relative risk of carrying an MDRO in humans with pet contact (including dogs, cats, rodents, birds, and reptiles) compared with those without pet contact.
The researchers calculated an increased risk of MRSA carriage for dog owners, with a risk ratio (RR) of 2.28 (95% confidence interval [CI], 1.47 to 3.56), but not for other pet owners. The meta-analysis for 3GCRE/CRE did not show a significantly higher risk for colonisation among pet owners compared with non-pet owners, with an RR of 1.18 (95% CI, 0.83 to 1.68) for pet owners in general. For VRE, there were insufficient data to perform a meta-analysis.
The study authors say the MRSA risk among dog owners is higher than found in literature reviews and, because of limitations concerning study populations and study designs, may be an overestimate. The data suggest that transmission occurs primarily from humans to dogs, who then may serve as a reservoir for reinfection and transmission to other household members. In addition, dogs may be a vector for livestock-associated strains of MRSA.
"If indeed pets play a role as a risk factor for MDRO acquisition in humans, our meta-analyses only suggested this relation for the transmission of MRSA via dogs," they wrote.
Pet husbandry as a risk factor for colonization or infection with MDR organisms: a systematic meta-analysis
Carolin Hackmann, Petra Gastmeier, Stefan Schwarz, Antina Lübke-Becker, Peter Bischoff, Rasmus Leistner
Published in the Journal of Antimicrobial Chemotherapy on 17 April 2021
MDR organisms (MDROs) pose a relevant risk for patients in modern healthcare. Although ownership of pet animals is common and owners and pets commonly live in close contact, it is still unclear whether pet ownership may be considered as a risk factor for MDRO acquisition prior to hospitalization.
We performed three separate meta-analyses in accordance with the PRISMA guidelines, assessing contact to pets as a risk factor for acquisition of MRSA, VRE and MDR Gram-negatives [namely third-generation cephalosporin-resistant Enterobacterales (3GCRE) and carbapenem-resistant Enterobacterales (CRE)].
We calculated an increased risk of MRSA carriage for dog owners [risk ratio (RR) 2.28, 95% CI 1.47–3.56]. Meta-analysis did not show a significantly higher risk for 3GCRE colonization among owners of different pet species compared with non-pet owners (RR 1.18, 95% CI 0.83–1.68 for pet owners in general, RR 0.88, 95% CI 0.56–1.40 for dog owners, RR 1.16, 95% CI 0.58–2.34 for cat owners, RR 1.34, 95% CI 0.43–4.18 for rodent owners, RR 0.91, 95% CI 0.38–2.18 for bird owners, and RR 2.34, 95% CI 0.33–16.63 for lizard/frog owners). For VRE, there were insufficient data to perform a meta-analysis.
Our analyses suggest contact to pet animals is a risk factor for MRSA, but not for 3GCRE/CRE acquisition. Evaluation of the underlying literature suggested a possible role of pet animals as: (i) vectors for the transmission of MDROs between livestock and humans; as well as (ii) a reservoir for MDROs. Pets, therefore, may promote transmission and reinfection of humans.