Clinical significance of polymicrobial bacteremia in newborns

Objective: To identify whether polymicrobial bacteremia in newborns is associated with any predisposing factors, distinguishing clinical features, or higher mortality. Methods: Results of blood cultures obtained over a period of 1 year from neonates admitted to the paediatric ward and Neonatal Intensive Care Unit of a tertiary care hospital were retrospectively analysed. The study group included all cases with polymicrobial bacteremia (isolation of two or more organisms). Controls (double the number of study cases) were randomly selected from the monomicrobial group. Case records of included cases were retrieved and scrutinized. Results: Of 770 positive cultures during the study period, 52 (6.8%) cultures were positive for more than one organism. Complete case records were retrieved for 40 polymicrobial and 78 monomicrobial cases. The two groups were comparable for maternal and neonatal parameters including: maternal and obstetric complications; period of gestation; mode of delivery; birthweight and perinatal asphyxia; clinical symptomatology; invasive therapeutic interventions; and mortality. Conclusions: Isolation of more than one organism from the blood culture of a suspected septic newborn is not rare. It does not always represent a true invasion by multiple organisms. Polymicrobial isolation per se should not be the criterion for hastily changing the therapeutic decisions.