Factors influencing oral colonization in premature infants.

BACKGROUND Factors influencing the oral flora of premature infants have not been adequately investigated. OBJECTIVE To investigate the effects of gestational age and of anti-bacterial therapy on the oral flora of premature infants. METHODS Oral cultures were obtained at age 1 day and age 10 days from 65 premature infants, divided into three groups: a) 24 neonates of 30-34 weeks gestation who did not receive ABT, b) 23 neonates of 30-34 weeks gestation who received ABT, and c) 18 neonates < 30 weeks gestation who received ABT. RESULTS Oral bacterial colonization increased from day 1 to day 10 of life. In 24-34 week neonates, gestational age did not affect early bacteremia or oral colonization at birth. Neither gestational age nor ABT affected late bacteremia or oral colonization at day 10. In 30-34 week neonates with ABT, the oral flora consisted mainly of non-Escherichia coli gram-negative bacteria, whereas those who did not receive ABT grew mainly alpha-hemolytic streptococci, Klebsiella pneumoniae and E. coli. In neonates < 30 weeks who received ABT the oral flora were mainly coagulase-negative staphylococci. Oral colonization with anaerobes was zero and colonization with fungi was minimal. CONCLUSIONS Acquisition of oral bacteria rose from day 1 to day 10 of life, regardless of gestational life or ABT. On day 10 of life, the spectrum of oral bacterial flora changed following ABT and consisted mainly of coagulase-negative Staphylococcus and non-E. coli gram-negative bacteria. Oral colonization showed few fungi but no anaerobes. These microbiologic observations merit attention when empirical anti-microbial therapy is considered in premature infants suspected of having late-onset sepsis.