74. Molecular Epidemiology of Staphylococcus aureus Colonizing Pets in Households of Children with Methicillin-Resistant S. aureus Skin and Soft Tissue Infections
Session: Oral Abstract Session: Pediatric Bacterial Infections and Colonization
Thursday, October 8, 2015: 8:45 AM
Room: 32--ABC

Companion animals can be colonized with Staphylococcus aureus. Our objective was to determine the molecular epidemiology of S. aureusin pets, their human contacts, and household environments.


From 2012-2015, this cross-sectional study enrolled 49 households of children with community-associated methicillin-resistant S. aureus (CA-MRSA) skin and soft tissue infection (SSTI) and ≥1 pet dog and/or cat. The nares and dorsal fur of indoor pet dogs and cats were cultured to detect S. aureus colonization. Household members’ nares, axillae, and inguinal folds and 21 household surfaces were cultured. Molecular typing of all S. aureus strains was performed by repetitive-sequence polymerase chain reaction to determine strain relatedness. Staphylococcal cassette chromosome mec (SCCmec) characterization was performed by multiplex PCR.


Of 49 households, 12 (24%) had ≥1 pet colonized with S. aureus. Of the 89 pets available for culture, 15 (17%) were colonized with S. aureus. Of 63 dogs, 13 (21%) were colonized with S. aureus (9 with MRSA); 2 of 26 (8%) cats were colonized with MRSA.  Eleven isolates were SCCmec type IV (MRSA), 1 type II (MRSA), and 2 type III (methicillin-susceptible S. aureus).

Of the 12 pet colonizing isolates (from 8 households) with an available index patient strain, 6 (50%) index patients’ strains (colonizing or infecting) were concordant with their pets’ colonizing strain. Eleven of 16 (69%) pet colonizing isolates were concordant with a household contact colonizing isolate. Of 12 pet colonizing isolates from households with an available environmental strain, 10 (83%) were concordant with an environmental strain. One dog colonized at both the nares and dorsal fur was colonized with concordant strains.

The primary caretaker for 10 (63%) of the colonized pets was also colonized with S. aureus (60% of these strains were concordant with the pet strain). Seven of 8 (88%) humans who shared a bed with a colonized pet were also colonized with S. aureus(43% of these strains were concordant with pet strain).


In households of children with MRSA infection, pet dogs and cats were often colonized with S. aureus. Their strains were likely to be concordant with strains found on both human and environmental surfaces.

Ryley Thompson, MCSE1, Patrick G. Hogan, MPH1, Melanie Sullivan, BS, MT1, Meghan Wallace, BS2, Carol Muenks, BA1, John Morelli, BS1, Jeff Wang, BS1, Carey-Ann D. Burnham, PhD2 and Stephanie Fritz, MD, MSCI3, (1)Pediatric Infectious Diseases, Washington University in St. Louis School of Medicine, Saint Louis, MO, (2)Pathology & Immunology, Washington University in St. Louis School of Medicine, St. Louis, MO, (3)Pediatric Infectious Diseases, Washington University School of Medicine in St. Louis, Saint Louis, MO


R. Thompson, None

P. G. Hogan, None

M. Sullivan, None

M. Wallace, None

C. Muenks, None

J. Morelli, None

J. Wang, None

C. A. D. Burnham, None

S. Fritz, None

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