Seasonal variation of Acinetobacter infections: 1987-1996

To determine whether nosocomial infections due to Acinetobacter species hav e increased over the past 10 years and whether infections continue to have a pronounced seasonal variation, we analyzed infections reported by hospita ls in the National Nosocomial Infections Surveillance System that performed adult and pediatric intensive care unit surveillance from 1987 through 199 6. 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 acine tobacter infections overall (P < .05) and of 2 major types of infection (P < .05): bloodstream infections (yearly median, 1.6 per 10,000 central venou s catheter-days; range, 1.3-2.9) and pneumonia (yearly median, 7.6 per 10,0 00 ventilator-days; range, 6.5-12.0). Throughout this period, average rates were significantly higher during July-October than during November-June fo r acinetobacter infections overall (8.0 vs. 5.2; P < .01) and for bloodstre am infections (2.0 vs. 1.2; P < .01) and pneumonia (9.7 vs. 6.6; P < .01).