Risk factors and molecular epidemiology of Acinetobacter baumannii bacteremia in neonates.

BACKGROUND: Acinetobacter baumannii infections in neonates are not uncommon but rarely studied.

METHODS: Clinical and molecular epidemiology of 40 patients with A. baumannii bacteremia in the neonatal intensive care units (NICUs) of a medical center from 2004 to 2014 was analyzed.

RESULTS: Multi-drug resistance was found in only 3 isolates (7.5%). Sequence types (STs) of A. baumannii defined by multilocus sequencing typing were diverse, and 72.4% identified isolates belonged to novel STs. Majority of the isolates were susceptible to antibiotics tested. Among the 3 imipenem-resistant A. baumannii (IRAB) isolates, 2 (66.7%) belonged to ST684, a novel ST. All of the 3 isolates were susceptible to tigecycline and colistin. The predominant mechanism of imipenem resistance in these neonatal isolates is ISAba1-blaOXA-80, which has never been reported in Asia before. Most infected newborns were premature (95%), with very low birth weight (70% < 1500 g), prolonged intubation, usage of percutaneous central venous catheter (65%) and long-term usage of total parenteral nutrition or intravenous lipid (95%). IRAB infection, inappropriate initial therapy, 1-minute Apgar score and early onset infection within the first 10 days of life were found to correlate with mortality by log-rank test. Prior use of imipenem for at least 5 days and use of high frequency oscillation ventilation (HFOV) were statistically significant risk factors for acquiring IRAB infections.

CONCLUSIONS: To reduce mortality of IRAB infection, it is crucial to consider giving effective agents, such as colistin, in 2 days for high risk neonates who has been given imipenem or used HFOV.