Factors affecting staphylococcus aureus colonization of the nasopharynx in the first 6 months of life

Janak A. Patel, Pedro Alvarez-Fernandez, Kristofer Jennings, Michael Loeffelholz, David Mccormick, Tasnee Chonmaitree

    Research output: Contribution to journalArticlepeer-review

    8 Scopus citations


    Background: Staphylococcal aureus (SA) colonization in early infancy is common, but the pattern and factors affecting its acquisition and persistence in the first few months of life are not well studied. The aim is to study the rate of SA nasopharyngeal (NP) colonization at monthly intervals in the first 6 months of life and its association with environmental and host factors and other pathogenic NP bacteria. Methods: Data from a prospective study were analyzed on bacterial cultures of 1765 NP swabs from 367 infants who were followed from birth to 6 months of age. Demographic, breastfeeding, cigarette smoke exposure and day care attendance data were collected at each monthly visit. Results: The rate of infants colonized with SA was highest at age 1 month (25%) and declined to lowest rate by age 6 months (12%). The proportion of SA strains that was methicillin-resistant SA was also highest at age 1 month and declined rapidly by age 4 months (18% vs. 6%, P = 0.05). Colonization with Streptococcus pneumoniae (SP), nontypeable Haemophilus influenzae (NTHI) and Moraxella catarrhalis (MC) increased at different rates up to age 6 months. Univariate analysis showed that SA colonization rate was significantly lower with increasing age, black race, day care attendance, and colonization with NTHI, MC and SP (P < 0.05). Multivariate analysis showed that this effect was independently associated only with increasing age and MC colonization (P < 0.05). Furthermore, the time to first acquisition of SA from one month of age onwards was significantly associated with day care attendance, and NTHI and MC colonization. None of the infants colonized with SA developed SA infections through age 6 months. Conclusions: SA colonization of NP begins very early in life and declines quickly. Methicillin-resistant SA has lower ability to maintain prolonged colonization status than methicillin-susceptible strains in the first 6 months of life. As the NP is colonized with other respiratory bacterial pathogens, the colonization with SA declines; however, this effect is stronger with Gram-negative bacteria, such as NTHI and MC.

    Original languageEnglish (US)
    Pages (from-to)826-830
    Number of pages5
    JournalPediatric Infectious Disease Journal
    Issue number8
    StatePublished - Aug 21 2015


    • Staphylococcus aureus
    • infants
    • nasopharyngeal colonization

    ASJC Scopus subject areas

    • Pediatrics, Perinatology, and Child Health
    • Microbiology (medical)
    • Infectious Diseases


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