The vulnerable very low birth weight infant: Late onset bloodstream infections

Objective: To review the epidemiology of late-onset bloodstream infections (LOBSI), evaluate risk factors associated with LOBSI and to compare our findings with the literature in light of new National Healthcare Safety Network (NHSN) birth weight categories. Design/methods: A retrospective case-controlled study of infants with LOBSI at ≥ 72 hours of life admitted to the NICU between 2000 and 2005. Infection rates were determined for birth weight categories adopted by the NHSN. The exposures of cases and controls to established risk factors were compared. Antimicrobial susceptibility patterns were evaluated. Results: A total of 4061 neonates were studied. LOBSI occurred in 150 (3.7%) of infants. Out of these 150, 196 episodes of infection occurred with 210 isolated pathogens. Most cases of LOBSI were in the infants whose birth weight was < 1000 grams (ELBW). Sepsis was associated with increased mortality (23%) in very low birth weight infants (p< 0.05). Coagulase-negative staphylococci were responsible for most cases; LOBSI due to Candidal infections were less common but associated with high mortality rates (37%) in the ELBW infant. Rates of methicillin-resistant Staphylococcus aureus remained low. Infants who developed LOBSI had prolonged exposures to a number of established risk factors. In the logistic regression analysis, bacteremia was associated with use of parenteral nutrition (OR =5.9) and umbilical catherization (OR= 32). Conclusions: ELBW infants had the highest rates of LOBSI. There was a low overall incidence of LOBSI due to yeast. However, infections with a Candida species were more common in ELBW infants and were associated with a higher mortality.