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Investigation of a multiyear multiple critical care unit outbreak due to relatively drug-sensitive Acinetobacter
Abstract:
From 1990 to 1993, an outbreak of respiratory Acinetobacter baumannii infection occurred in five intensive care units (ICUs) of a tertiary care center. A. baumannii was subsequently isolated from disinfected temperature probes and ventilator circuits. Pulsed-field gel electrophoresis suggested that a single strain accounted for 93% of patient isolates and 88% of environmental isolates. Univariate risk factors for A. baumannii acquisition were tracheostomy (P < .01), ventilation >3 days (P < .01), dialysis (P = .03), Stenotrophomonas maltophilia respiratory colonization (P = .02), parenteral nutrition (P = .05), and enteric feeding (P < .01). Logistic regression analysis showed duration of ventilation and enteric feeding to be independent risk factors. The outbreak strain was relatively antibiotic-susceptible, but the mortality attributable to respiratory A. baumannii acquisition was 23%. Only the APACHE II score was independently associated with increased mortality. Multifaceted control measures, including gas sterilization of temperature probes, terminated the outbreak.
Insights
An Acinetobacter baumannii outbreak in ICUs was linked to contaminated equipment. Key risk factors included ventilation and feeding methods, with gas sterilization effectively ending the outbreak.
Area of Science:
- Infectious Diseases
- Critical Care Medicine
- Microbiology
Background:
- An outbreak of respiratory Acinetobacter baumannii occurred in five intensive care units (ICUs) between 1990 and 1993.
- Acinetobacter baumannii was identified in disinfected temperature probes and ventilator circuits, suggesting environmental contamination.
Purpose of the Study:
- To investigate the source, risk factors, and outcomes of an Acinetobacter baumannii outbreak in ICUs.
- To identify effective control measures for Acinetobacter baumannii outbreaks.
Main Methods:
- Pulsed-field gel electrophoresis (PFGE) was used to analyze patient and environmental isolates.
- Univariate and logistic regression analyses identified risk factors for Acinetobacter baumannii acquisition.
- Mortality was assessed in relation to clinical factors, including the APACHE II score.
Main Results:
- A single strain of Acinetobacter baumannii accounted for 93% of patient and 88% of environmental isolates.
- Independent risk factors for acquisition included prolonged ventilation and enteric feeding.
- The attributable mortality rate was 23%, with APACHE II score being the only independent predictor of mortality.
Conclusions:
- Contaminated medical equipment and specific patient care practices contributed to the Acinetobacter baumannii outbreak.
- Multifaceted control measures, including gas sterilization of temperature probes, successfully terminated the outbreak.
- Effective infection control strategies are crucial for managing Acinetobacter baumannii in ICUs.