SAN FRANCISCO—Antibiotic resistance increased rapidly in nosocomial Acinetobacter infections from 1994 to 2004, growing almost fourfold, according to a report from the Centers for Disease Control and Prevention.
During that 10-year period, 8,537 cases of Acinetobacter infection were reported to the National Nosocomial Infection Surveillance System, of which 3,601 had susceptibility testing results.
The testing results indicate that the number of isolates that were susceptible to only one of four classes of antibiotics rose from 14% to 26%, and the number of isolates resistant to all four classes increased from 4% to 15%, Roberta Carey, Ph.D., reported in a poster presentation at the annual Interscience Conference on Antimicrobial Agents and Chemotherapy.
The classes were β-lactams, fluoroquinolones, aminoglycosides, and carbapenems. Resistance to a β-lactam antibiotic rose from 39% of isolates to 66% during the 10-year period. For fluoroquinolones, resistance rose from 50% to 73% of isolates; for aminoglycosides, from 19% to 31%; and for carbapenems, from 9% to 39%.
The review also indicates that a greater percentage of the resistant infections came from hospitals in the Northeast than from hospitals elsewhere, and that they came from larger hospitals.
Only 24% of the hospitals reporting to the surveillance system were in the Northeast, but 74% of the isolates resistant to all four antibiotic classes came from that region, said Dr. Carey, of the CDC's Division of Health Care Quality Promotion. Only 12% of resistant isolates came from the West.
Less than 1% of the Acinetobacter infections came from hospitals with fewer than 200 beds, while 55% came from hospitals with more than 500 beds. In fact, 99% of isolates resistant to all four classes came from large teaching hospitals, although 83% of the hospitals that report to the system are teaching hospitals.
A preponderance of the Acinetobacter infections came from hospitals in the northern New Jersey and New York City areas, and many were associated with severe burns, Dr. Carey said in an interview after the meeting, which was sponsored by the American Society for Microbiology.
Isolates that were nonsusceptible to all four classes of antibiotics caused pneumonia in 46% of cases, bloodstream infections in 13%, urinary tract infections in 11%, surgical site infections in 10%, and other infections in 20%.