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Ventilator-related Acinetobacter outbreak in an intensive care unit
T R Cox1, W E Roland, M E Dolan
1Harry S Truman Memorial Veterans Hospital, Columbia, MO 65201, USA.
Abstract:
An outbreak of 16 cases of ciprofloxacin-resistant Acinetobacter baumannii (calcoaceticus subspecies anitratus) infections occurred during a 7-month period in a medical intensive care unit. Fifteen of the patients developed pneumonia associated with ventilator support. Possible sources considered in the outbreak investigation were sinks, ice, personnel, patients on multiple antibiotic therapy, reusable ventilator circuits, and hemodialysis. The equipment and environment associated with the outbreak were cultured. Patients on ventilators were significantly more susceptible to Acinetobacter nosocomial infection compared with the rest of the patients in the medical intensive care unit (p < 0.05). Sputum cultures were only 5% sensitive to ciprofloxacin and gentamicin, but they were 100% sensitive to imipenem (p < 0.0001). Uncloaking imipenem was a significant contributing factor in controlling this outbreak. Once outbreak control measures were instituted, Acinetobacter isolates dropped from 77 (during the outbreak year) to 9 (during the subsequent year) and no new pneumonia cases occurred.
Insights
An outbreak of ciprofloxacin-resistant Acinetobacter baumannii pneumonia in an ICU was controlled by identifying imipenem as the effective treatment. This led to a significant decrease in Acinetobacter infections and no new pneumonia cases.
Area of Science:
- Infectious Diseases
- Critical Care Medicine
- Microbiology
Background:
- Acinetobacter baumannii is a significant cause of nosocomial infections, particularly in intensive care units.
- Ciprofloxacin-resistant strains pose a therapeutic challenge, complicating treatment strategies.
- Ventilator-associated pneumonia (VAP) is a common complication in critically ill patients.
Purpose of the Study:
- To investigate an outbreak of ciprofloxacin-resistant Acinetobacter baumannii infections in a medical intensive care unit.
- To identify the source and contributing factors of the outbreak.
- To determine effective treatment strategies and control measures for Acinetobacter infections.
Main Methods:
- Retrospective analysis of 16 cases of Acinetobacter baumannii infections over a 7-month period.
- Environmental and equipment cultures to identify potential sources.
- Antimicrobial susceptibility testing of Acinetobacter isolates.
- Comparison of infection rates between ventilated and non-ventilated patients.
Main Results:
- Fifteen of 16 patients developed ventilator-associated pneumonia.
- Patients on ventilators were significantly more susceptible to Acinetobacter infection (p < 0.05).
- Sputum cultures showed 100% sensitivity to imipenem, compared to 5% for ciprofloxacin and gentamicin (p < 0.0001).
- Implementation of imipenem therapy and control measures reduced Acinetobacter isolates from 77 to 9 in the subsequent year.
Conclusions:
- Imipenem was highly effective against the outbreak strain of Acinetobacter baumannii.
- Prompt identification and implementation of effective antimicrobial therapy (imipenem) were crucial in controlling the outbreak.
- Enhanced infection control measures, including appropriate antibiotic use, are vital in preventing and managing nosocomial Acinetobacter infections.