Major Article
How important is patient-to-patient transmission in extended-spectrum β-lactamase Escherichia coli acquisition

https://doi.org/10.1016/j.ajic.2006.09.011Get rights and content

Background

Extended-spectrum β-lactamase (ESBL)-producing Escherichia coli is an emerging pathogen. The causal role of antibiotic selective pressure versus patient-to-patient transmission has not been assessed. The objective of this study was to quantify the amount of patient-to-patient transmission among patients who acquire an ESBL-producing E coli infection using perianal surveillance cultures in an intensive care unit (ICU) population.

Methods

A prospective cohort of patients admitted between September 1, 2001, and September 1, 2004, to the medical and surgical ICUs at a tertiary care hospital was studied. Patients had perianal cultures on admission, weekly, and upon discharge. Strain typing by pulsed-field gel electrophoresis (PFGE) and epidemiologic criteria were used to quantify the amount of patient-to-patient transmission.

Results

There were 1806 patients admitted to the ICUs. There were 74 patients who had ESBL-producing E coli on admission to the ICU and 23 patients who acquired ESBL-producing E coli. Among these 23 patients, there were 14 PFGE types, and 3 (13%) patient acquisitions were defined as patient-to-patient transmission by similar PFGE type and overlapping time in the hospital.

Conclusion

Our data suggest that patient-to-patient transmission is not an important cause of the acquisition of ESBL-producing E coli colonization in the ICU setting.

Section snippets

Study design and patient population

This study was approved by the Institutional Review Board of the University of Maryland, Baltimore. This study utilized a prospective cohort of adult patients admitted to the medical ICU (MICU) and surgical ICU (SICU) of the University of Maryland Medical Center (UMMC) between September 1, 2001, and September 1, 2004. The UMMC is a tertiary care facility in Baltimore, Maryland. The MICU is a 10-bed, private room unit providing care to patients who have acute or potentially life-threatening

Results

There were 1806 patients admitted to the MICU and SICU during the 3-year study period who had admission and discharge cultures obtained. Compliance with obtaining perianal surveillance cultures (admission and discharge) was greater than 90% on average. Mean demographics of these patients are as follows: age, 55.7 years; female, 46%; Charlson score, 2.3; chronic disease score, 7.8; average time in hospital before ICU admission, 2.6 days; average numbers of days in the ICU, 6.8 days.

Ninety-seven

Discussion

In this study, we quantified the amount of patient-to-patient transmission of ESBL-producing E coli that occurred in a tertiary care hospital over a 3-year period. To our knowledge, we are the first to focus this quantification for ESBL-producing E coli in the setting of gastrointestinal colonization. We found that, of the 23 patients who acquired colonization with ESBL-producing bacteria, 3 (13%) had patient-to-patient transmission, defined as similar PFGE type and epidemiologic hospital time

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Supported by the National Institutes of Health grants K23 AI01752-01A1 and R01 AI60859-01A1.

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