To determine whether
nosocomial infections due to Acinetobacter species have increased over the past 10 years and whether
infections continue to have a pronounced seasonal variation, we analyzed
infections reported by hospitals in the National
Nosocomial Infections Surveillance System that performed adult and pediatric intensive care unit surveillance from 1987 through 1996. Overall, 3447 nosocomial
acinetobacter infections were reported during 5,596, 156 patient-days. There was a yearly median of 7.2
infections (range, 5.0-10.5) per 10,000 patient-days and a downward trend in the rate of
acinetobacter infections overall (P<.05) and of 2 major types of
infection (P<.05):
bloodstream infections (yearly median, 1.6 per 10, 000
central venous catheter-days; range, 1.3-2.9) and
pneumonia (yearly median, 7.6 per 10,000
ventilator-days; range, 6.5-12.0). Throughout this period, average rates were significantly higher during July-October than during November-June for
acinetobacter infections overall (8.0 vs. 5.2; P<.01) and for
bloodstream infections (2.0 vs. 1.2; P<.01) and
pneumonia (9.7 vs. 6.6; P<.01).