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 life, regardless of gestational life or ATB. On day 10 of life, the spectrum of oral bacterial flora changed following ATB 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.