Bacterial colonization in intubated newborns

The bacteriology of tracheal aspirates from 127 newborns was studied. Specimens were obtained twice a week as long as the newborns were intubated. Each newborn had between one and eight specimens taken (average 1.7). 127 babies had one specimen taken, 38 had two, 25 had three, 12 had four, and 10 had more than four specimens taken, which made a total of 212 specimens. No bacterial or fungal growth was obtained from 65 specimens, whereas the remaining specimens (147) yielded 209 bacterial and fungal isolates accounting for 1.4 isolates per specimen. The total isolates recovered were 168 aerobes, 36 anaerobes, and 5 Candida albicans. Of this total, 70 specimens yielded one isolate, 48 two isolates, 6 three isolates, 5 four isolates, and one aspirate yielded five isolates. 78 newborns (61%) received antimicrobial therapy. A higher incidence of positive cultures and the presence of more than one organism per culture were found in those infants not receiving antibiotics. More isolates per specimen were noted with increasing time of incubation. The rate of isolation Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella pneumoniae remained constant with increased length of intubation, the rate of recovery of Staphylococcus epidermidis, viridans group streptococci, and Propionibacterium acnes increased, and the rate of isolation of Escherichia coli and anaerobic organisms decreased.