Nonpathogenic bacterial flora and immunoglobulin A in the oral cavity inhibit colonization of methicillin-resistant Staphylococcus aureus in very low birth weight infants

Tomohiko NakamuraDivision of Neonatology, Nagano Children's Hospital, Toyoshina, Azumino City, Nagano, JapanBackground: The aim of this prospective study was to investigate if nonpathogenic bacterial flora and high concentrations of immunoglobulin A in the oral cavity inhibit colonization with methicillin-resistant Staphylococcus aureus (MRSA) in very low birth weight infants.Methods: We retrospectively analyzed MRSA colonization during hospitalization in 29 preterm infants with a birth weight < 1500 g who were admitted to the neonatal intensive care unit at Nagano Children's Hospital. We compared the incidence of MRSA colonization in 12 infants who had nonpathogenic bacterial flora and high concentrations of IgA (>2 mg/dL) in the oral cavity with 17 infants who did not.Results: MRSA colonization in infants who had nonpathogenic bacterial flora and high concentrations of immunoglobulin A was significantly lower than in other infants (P < 0.01).Conclusion: These results indicate that nonpathogenic bacterial flora and high concentrations of immunoglobulin A in the oral cavity may protect against MRSA colonization in very low birth weight infants.Keywords: nonpathogenic bacterial flora, immunoglobulin A, methicillin-resistant Staphylococcus aureus, very low birth weight infants