Risk factors for antimicrobial resistance among Staphylococcus isolated from pets living with a patient diagnosed with methicillin-resistant Staphylococcus aureus infection

Abstract

It has been suggested that pets play a critical role in the maintenance of methicillin-resistant (MR) and multidrug-resistant (MDR) Staphylococcus spp. in the household. We examined risk factors for carriage of antimicrobial-resistant coagulase-positive staphylococci, with particular attention to Staphylococcus aureus and Staphylococcus pseudintermedius isolated from pets living in households of people diagnosed with methicillin-resistant S. aureus (MRSA) skin or soft-tissue infection. We analyzed data collected cross-sectionally from a study conducted in 2012 that evaluated the transmission of MRSA and other staphylococci from humans, their pets and the environment (Pets and Environmental Transmission of Staphylococci [PETS] study). We used unadjusted and adjusted stratified logistic regression analyses with household-clustered standard errors to evaluate the association between demographic, healthcare-related, contact-related and environmental risk factors and MDR Staphylococcus spp. isolated from dogs and cats. Staphylococcal isolates obtained from dogs (n = 63) and cats (n = 47) were included in these analyses. The use of oral or injectable antimicrobials by the pets during the prior year was the main risk factor of interest. Based on our results, 50% (12/24) of S. aureus, 3.3% (1/30) of S. pseudintermedius and 25% (14/56) of other coagulase-positive staphylococci (CPS) were determined to be MDR. S. aureus isolates were more likely to be MDR compared with S. pseudintermedius. We did not find a significant statistical association between the use of oral or injectable antimicrobials in the prior year and the presence of MDR bacteria. The results suggest that drivers of antimicrobial resistance in household staphylococci may vary by bacterial species, which could have implications for one health intervention strategies for staphylococci and inform the investigation of other reverse zoonoses, such as COVID-19.

Keywords: Staphylococcus; antimicrobial resistance; domestic animals; multidrug resistance.

FIGURE 1

Conceptual framework of possible demographic, healthcare‐related, contact‐related and environmental risk factors for multidrug‐resistant Staphylococcus in dogs and cats. The proposed relationship of the variables of interest and the outcome of the primary model (MDR, defined as acquired nonsusceptibility to at least one agent in three or more antimicrobial classes of the ten that were tested) (Magiorakos et al., 2012) are shown in this figure. According to this conceptual framework, some variables have direct effects on MDR, while others are indirectly related to the outcome of interest

FIGURE 2

Patterns of antimicrobial resistance among pet's and environmental MRSA isolates. A red box shows the pet's isolate was resistant. An orange box shows the environmental isolate was resistant. fox – cefoxitin; amk – amikacin; e – erythromycin; cip – ciprofloxacine; gm – gentamicin; cc – clindamycin; sxt – trimethoprim/sulfamethoxazole; tet – tetracycline. *Quinupristin/dalfopristin, chloramphenicol and linezolid were excluded from this figure because none of the isolates were resistant to these antimicrobials. House IDs were harmonized with Table 3 (spa typing at baseline) in Cotter et al.,