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Risk factors for imipenem-resistant Pseudomonas aeruginosa among hospitalized patients
Anthony D Harris1, David Smith, Judith A Johnson
1Department of Epidemiology and Preventive Medicine, University of Maryland, VA Maryland Health Care System, 10 N. Greene St. BT111, Baltimore, MD 21201 , USA. aharris@epi.umaryland.edu
Abstract:
Risk factors for the nosocomial recovery of imipenem-resistant Pseudomonas aeruginosa (IRPA) were determined. A case-control study design was used for the comparison of 2 groups of case patients with control patients. The first group of case patients had nosocomial isolation of IRPA, and the second group had imipenem-susceptible P. aeruginosa (ISPA). Control patients were selected from the same medical or surgical services from which case patients were receiving care when isolation of IRPA occurred. Risk factors analyzed included antimicrobials used, comorbid conditions, and demographic variables. IRPA was recovered from 120 patients, and ISPA from 662 patients. Imipenem (odds ratio [OR], 4.96), piperacillin-tazobactam (OR, 2.39), vancomycin (OR, 1.80), and aminoglycosides (OR, 2.19) were associated with isolation of IRPA. Vancomycin (OR, 1.64), ampicillin-sulbactam (OR, 2.00), and second-generation cephalosporins (OR, 2.00) were associated with isolation of ISPA. Antibiotics associated with ISPA are different from antibiotics associated with IRPA. The OR for imipenem as a risk factor for IRPA is less than that reported from studies in which control group selection was suboptimal.
Insights
Identifying risk factors for hospital-acquired imipenem-resistant Pseudomonas aeruginosa (IRPA) is crucial. Specific antibiotic exposures, unlike those for susceptible strains, are linked to IRPA recovery in nosocomial settings.
Area of Science:
- Infectious Diseases
- Clinical Microbiology
- Hospital Epidemiology
Background:
- Nosocomial infections pose a significant threat to patient safety.
- The emergence of antibiotic-resistant bacteria, such as imipenem-resistant Pseudomonas aeruginosa (IRPA), complicates treatment strategies.
- Understanding risk factors for IRPA acquisition is essential for implementing effective infection control measures.
Purpose of the Study:
- To determine the specific risk factors associated with the nosocomial recovery of imipenem-resistant Pseudomonas aeruginosa (IRPA).
- To compare risk factors for IRPA isolation versus imipenem-susceptible P. aeruginosa (ISPA) isolation.
- To evaluate the influence of prior antimicrobial exposure on IRPA acquisition.
Main Methods:
- A case-control study design was employed.
- Case patients with nosocomial IRPA isolation were compared to control patients with nosocomial ISPA isolation.
- Risk factors analyzed included antimicrobial use, comorbid conditions, and demographic variables.
Main Results:
- Imipenem, piperacillin-tazobactam, vancomycin, and aminoglycosides were significantly associated with IRPA isolation.
- Vancomycin, ampicillin-sulbactam, and second-generation cephalosporins were associated with ISPA isolation.
- The odds ratio for imipenem as a risk factor for IRPA was lower than in previous studies with suboptimal control groups.
Conclusions:
- The antibiotic exposures linked to ISPA differ from those associated with IRPA.
- Prior exposure to specific antibiotics, including imipenem, is a significant risk factor for nosocomial IRPA acquisition.
- Optimized control group selection in case-control studies is critical for accurate risk factor assessment.