E. faecalis and P. aeruginosa are useful epidemiological markers for the analysis of transmission events on intensive care units

Abstract number: O140

Kola A., Schwab F., Bärwolff S., Eckmanns T., Weist K., Dinger E., Klare I., Witte W., Rüden H., Gastmeier P.

Objectives: At least 15% of nosocomial infections in intensive care units are due to the cross-transmission of causative organisms between patients. In contrast to endogenous infections, these exogenous infections are more likely to be prevented by infection control measures. Therefore, knowledge of surrogate organisms for the analysis of patient-to-patient transmissions would be useful.

Methods: As known from KISS, the German hospital infection surveillance system, A. baumannii, E. faecium, E. faecalis, K. pneumoniae, P. aeruginosa and S. aureus are amongst the most common pathogens responsible for nosomial infections in ICUs. Over a two years period, primary isolates of these six "indicator" organisms cultured from clinical samples of patients who stayed at 11 ICUs at two University hospitals were genotyped by PFGE (pulsed field gel electrophoresis). Genetically indistinguishable isolates from different patients were considered as cross-transmissions if the patients were hospitalised on the same ICU in a temporal proximity of at least 9 days. The association between the isolation of each of the six pathogens and cross transmission (transmission events per 1000 patient days and per 100 cultured organisms) was analysed.

Results: During 100 781 patient days, 100 829 microbiological specimens from 24 362 patients were sampled (average investigation density of 1.0 sample per patient * day) and 3 370 indicator organisms were cultured (29.1%S. aureus, 22.6%E. faecalis, 22.2%P. aeruginosa, 14.6%E. faecium, 8.3%K. pneumoniae, 3.1%A. baumannii). Altogether, 416 cross-transmissions (incidence density of 4.1 transmissions per 1 000 patient days, ranging between 1.4–8.4 per 1 000 patient days depending on the respective ICU) were discerned. Of these, 19% were due to E. faecalis, 14% to E. faecium, 11% to P. aeruginosa resp. S. aureus, and 6.4% to A. baumannii. There was a significant correlation between the isolation of E. faecalis and P. aeruginosa, and transmissions per 1000 patient days resp. per 100 cultured organisms (Spearman correlation coefficient >0.8, p < 0.01).

Conclusion:E. faecalis and P. aeruginosa are useful epidemiological markers for the analysis of patient-to-patient transmissions on ICUs in non-outbreak settings. As cross-transmissions are indicative of poor clinical care, transmission analysis of E. faecalis and P. aeruginosa may be used to monitor adherence to standard infection control precautions.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
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