1746. Antimicrobial Susceptibility Profiles of Staphylococcus aureus (SA) Isolates Recovered from Humans, Environmental Surfaces, and Companion Animals in Households of Children with Community-Associated Methicillin-Resistant S. aureus (CA-MRSA) Infections
Session: Poster Abstract Session: Pediatric Bacterial Infections
Saturday, October 10, 2015
Room: Poster Hall
Posters
  • Antibiogram IDSA Poster 9-30-15 FINAL.pdf (706.1 kB)
  • Background:

    Households pose a reservoir for CA-MRSA transmission. We determined antibiotic susceptibility profiles of SA isolates recovered from households of patients with CA-MRSA infections.

    Methods:

    Children (n=110) with acute CA-MRSA infection and their household contacts (n=388) were evaluated up to 10 times over 24 months. Cultures were obtained from participants' axillae, anterior nares, and inguinal folds, up to 21 household objects, and indoor pets (n=92).  Kirby-Bauer disk diffusion determined SA susceptibility (Table). In accordance with Clinical and Laboratory Standards Institute guidelines for antibiogram generation, the analysis included only the first SA isolate recovered from each companion animal, household object, or human body site.

    Results:

    Overall, 1633 isolates were evaluated; MRSA comprised 52% of the SA isolates recovered from household surfaces, 52% from human colonization cultures, and 62% of pet isolates (Table). Fomites with the highest prevalence of MRSA were the bathtub soap bar/dish (71%), bathroom hand towel (68%), and the telephone (64%). All isolates were susceptible to trimethoprim-sulfamethoxazole, linezolid, ceftaroline and rifampin. The prevalence of high-level mupirocin resistance was 4% overall.   

    Conclusion:

    Our results demonstrate heterogeneity of SA isolates recovered in the environment of CA-MRSA infected patients, with prevalent susceptibility to many antibiotics prescribed in outpatient settings.

     


    Table. Antimicrobial susceptibility profiles of S. aureus isolates recovered from households of children with documented CA-MRSA infection

    Location Isolate Recovered

    Number S. aureus isolates tested

    % Susceptible

    % MDR4b

    METa

    CLI

    ERY

    TET

    CIP

    MUP

    Overall

    1633

    45

    90

    47

    98

    68

    96

    4

       People

    770

    42

    90

    44

    98

    65

    96

    4

          Index Patient Infection

    110

    0c

    94

    17

    99

    42

    98

    9

          Index Patient Colonization

    153

    44

    89

    46

    99

    67

    94

    3

          Household Contacts Colonization

    507

    50

    89

    49

    98

    68

    96

    4

       Pets

    48

    38

    85

    48

    100

    69

    96

    8

       Environment

    815

    48

    90

    50

    98

    71

    97

    3

    Abbreviations: MET, methicillin; CLI, clindamycin; ERY, erythromycin; TET, tetracycline; CIP, ciprofloxacin; MUP, mupirocin; MDR4, multi-drug resistance

    a As predicted by cefoxitin testing

    b MDR4: resistance to β-lactams plus 3 additional systemic antimicrobial classes

    c Study entry required a MRSA infection

     

    John Morelli, BS1, Patrick G. Hogan, MPH1, Melanie Sullivan, BS, MT1, Meghan Wallace, BS2, Carol Muenks, BA1, Jeff Wang, BS1, Ryley Thompson, MCSE1, 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

    Disclosures:

    J. Morelli, None

    P. G. Hogan, None

    M. Sullivan, None

    M. Wallace, None

    C. Muenks, None

    J. Wang, None

    R. Thompson, None

    C. A. D. Burnham, None

    S. Fritz, None

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