FULMINANT LATE-ONSET SEPSIS IN A NEONATAL INTENSIVE CARE UNIT

Background: The distribution of pathogens causing fulminant late-onset sepsis in the neonatal intensive care unit (NICU) may differ significantly from that causing late-onset sepsis, in general. The difference may be important in selection of empiric antibiotic therapy when fulminant sepsis is suspected. Objective: To determine the pathogens and clinical features associated with fulminant late-onset sepsis in a NICU. Methods: A retrospective study was conducted of sepsis in infants in a NICU over a ten-year period (1988-97). Late-onset sepsis was defined as one or more positive blood cultures obtained after 3 days of age in the presence of clinical features of sepsis. Cultures with the same organism within 30 days of first isolation were considered one episode. Sepsis was defined as fulminant if death occurred within 48 hours of initial blood cultures. Coagulase-negative staphylococcal sepsis was defined as at least two positive blood cultures. Polymicrobial sepsis was counted as multiple individual episodes of sepsis. Cases were identified from a computerized microbiology database. Demographic data were provided by a computerized neonatal database. Clinical features were determined by examination of medical records. Results: There were 6,275 admissions to the NICU over the ten-year study period (1988-97). There were 831 episodes of late-onset sepsis occurring in 542 infants. The most common pathogens were coagulase-negative staphylococci 278 (33%), Candida sp. 143 (17%), Enterococcus sp. 83 (10%), S. aureus 69 (8%), S. agalactiae 36 (4%), and Pseudomonas sp. 36 (4%). There were 49 cases of fulminant late-onset sepsis in 43 infants. Six cases were polymicrobial. Infants with fulminant sepsis had median birth weight = 870 g (range: 437-3515), median gestational age = 26 wk (range: 23-40), and median age of sepsis = 19 days (range: 6-304). The most common causes of fulminant late-onset sepsis were Pseudomonas sp. 20 (40%), E. coli 5 (10%), Enterobacter sp. 4 (8%), Candida sp. 4 (8%), S. aureus 4 (8%), and coagulase-negative staphylococci 4 (8%). Thirty-four of 49 (69%; 95%CI: 55%-82%) cases of fulminant late-onset sepsis were due to gram-negative organisms. The fulminant case fatality rate was highest for Pseudomonas sp., 20 of 36 (56%; 95%CI: 38%-72%) and lowest for coagulase-negative staphylococci, 4 of 278 (1%; 95%CI: 0-4%), odds ratio 86; 95%CI: 26-280. Conclusions: The distribution of pathogens causing fulminant late-onset sepsis in the NICU differed significantly from that causing late-onset sepsis, especially concerning the predominance of Pseudomonas sp. and other gram-negative organisms. When fulminant sepsis is suspected, the selection of empiric antibiotic therapy should account for these differences.
Aqil E. Surka, MD E. Stephen Buescher, MD, M. Gary Karlowicz, MD, FAAP; Department of Pediatrics, Eastern Virginia Medical School, Norfolk, [...]