Ten-year survey of positive blood cultures among admissions to a neonatal intensive care unit.

A 10-year survey of positive blood cultures was conducted among 6,616 infants admitted to an intensive care unit from 1974-1983. Group B streptococci (59) and E. coli (32) were the most common pathogenic organisms isolated from the early onset group (less than 72 hours of age). The percentage of infants with bacteremia, the birth weight distribution of infected infants, and the organisms isolated did not change in the early onset group throughout the study period. Coagulase negative staphylococci (471), S. aureus (126), E. coli (33), Klebsiella sp. (30), and enterococci (30) were the most frequent organisms isolated from the late onset group. The frequency of infection in the late onset group did not change as a function of time but was associated with decreasing birth weight during the study period. Methicillin and gentamicin resistance among coagulase negative staphylococci preceded that of S. aureus by one to three years, suggesting interspecies transfer of bacterial resistance among staphylococci. The data indicate that whereas the epidemiology of early-onset septicemia has remained relatively stable during the study period, the incidence of late onset bacteremia is increasing with improved survival rates of low birth weight infants. Antibiotic administration in the late onset group should include consideration of hospital-acquired, multiply antibiotic resistant organisms as well as maternally-acquired bacterial flora.