The Role of Patient-to-Patient Transmission in the Acquisition of Imipenem-Resistant Pseudomonas aeruginosa Colonization in the Intensive Care Unit

Department of Pathology, Institute of Genomic Sciences, University of Maryland School of Medicine, 10 South Pine Street, Baltimore, MD 21201, USA.
The Journal of Infectious Diseases (Impact Factor: 6). 09/2009; 200(6):900-5. DOI: 10.1086/605408
Source: PubMed


Imipenem-resistant Pseudomonas aeruginosa (IRPA) is an emerging problem. The causal role of antibiotic selective pressure versus patient-to-patient transmission has not been assessed using a large cohort.
Patients who were admitted to the medical and surgical intensive care units (ICUs) at the University of Maryland Medical Center from 2001 through 2006 had multiple perianal culture samples collected. Using pulsed-field gel electrophoresis (PFGE), the number of patients who acquired IRPA as a result of patient-to-patient transmission was determined. We also analyzed a subset of patients who had a previous surveillance culture that grew an imipenem-susceptible P. aeruginosa (ISPA) and a subsequent culture that grew IRPA.
Our cohort consisted of 7071 patients. Three hundred patients were colonized with IRPA. 151 patients had positive culture findings at ICU admission, and 149 patients acquired an IRPA. Among the patients who acquired IRPA, 46 (31%) had a PFGE pattern similar to that for another isolate, and 38 (26%) were found to be colonized with an ISPA on the basis of earlier culture results. Of the 38-patient subset, 28 (74%) had identical PFGE patterns.
Our data showed that, of those cases of IRPA acquisition, 46 (31%) were defined as cases of patient-to-patient transmission, and 28 (19%) were cases of acquisition by the patients' endogenous flora.

6 Reads
  • Source
    • "In our study, the classical binary endogenous/exogenous scheme [12,22] is transcended by the interaction of both factors, which confirms that P. aeruginosa acquisition is complex. In the past, some molecular epidemiology studies have reported a significant role of exogenous colonization [4-7,18], whereas others have predominantly identified the role of endogenous colonization [11,13]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to investigate the relationship among Pseudomonas aeruginosa acquisition on the intensive care unit (ICU), environmental contamination and antibiotic selective pressure against P. aeruginosa. An open, prospective cohort study was carried out in a 16-bed medical ICU where P. aeruginosa was endemic. Over a six-month period, all patients without P. aeruginosa on admission and with a length of stay >72 h were included. Throat, nasal, rectal, sputum and urine samples were taken on admission and at weekly intervals and screened for P. aeruginosa. All antibiotic treatments were recorded daily. Environmental analysis included weekly tap water specimen culture and the presence of other patients colonized with P. aeruginosa. A total of 126 patients were included, comprising 1,345 patient-days. Antibiotics were given to 106 patients (antibiotic selective pressure for P. aeruginosa in 39). P. aeruginosa was acquired by 20 patients (16%) and was isolated from 164/536 environmental samples (31%). Two conditions were independently associated with P. aeruginosa acquisition by multivariate analysis: (i) patients receiving ≥3 days of antibiotic selective pressure together with at least one colonized patient on the same ward on the previous day (odds ratio (OR) = 10.3 ((% confidence interval (CI): 1.8 to 57.4); P = 0.01); and (ii) presence of an invasive device (OR = 7.7 (95% CI: 2.3 to 25.7); P = 0.001). Specific interaction between both patient colonization pressure and selective antibiotic pressure is the most relevant factor for P. aeruginosa acquisition on an ICU. This suggests that combined efforts are needed against both factors to decrease colonization with P. aeruginosa.
    Critical care (London, England) 02/2011; 15(1):R55. DOI:10.1186/cc10026 · 4.48 Impact Factor
  • Source
    The Journal of Infectious Diseases 09/2009; 200(6):838-40. DOI:10.1086/605409 · 6.00 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Infections caused by multidrug-resistant organisms (MDROs), including Acinetobacter, have complicated the care of military personnel injured in Operations Iraqi and Enduring Freedom. Cumulative data suggest that nosocomial transmission of MDROs in deployed medical treatment facilities (MTFs) has contributed to these infections. A 2008 review of deployed MTFs identified multiple factors impeding the performance of infection prevention and control (IC) practices. In response, efforts to emphasize IC basics, improve expertise, and better track MDRO colonization were pursued. Efforts to increase awareness and enhance IC in deployed MTFs were focused on educating leaders and deploying personnel, producing deployed IC resources, and standardizing level IV and V admission screening for MDRO colonization. A repeat mission in 2009 reviewed interval progress. Increased awareness and the need for emphasis on basic IC practice, including hand hygiene, use of transmission-based (isolation) precautions, and cohorting of patients, were imparted to leaders and deploying personnel through briefings, presentations, and an All Army Activities message. Enhancement of IC expertise was implemented through increased standardization of IC practice, establishment of a predeployment IC short course, an IC teleconsultation service, and dedicated Internet resources. Standardization of admission colonization screening of personnel evacuated from the combat theater was established to better define and respond to the MDRO problem. A repeat review of the deployed MTFs found overall improvement in IC practice, including clear command emphasis in the Iraqi theater of operations. Maintaining a strong IC effort in the deployed setting, even in a stabilized operational environment, is difficult. Use of innovative strategies to enhance expertise and practice were implemented to reduce MDRO infections.
    The Journal of trauma 07/2010; 69 Suppl 1:S94-101. DOI:10.1097/TA.0b013e3181e44b3f · 2.96 Impact Factor
Show more


6 Reads
Available from