Pseudo outbreak of Pseudomonas mendocina in stem cell-cultures

Abstract number: P1321

Tschudin S., Arber C., Tichelli A., Nogarth D., Dangel M., Frei R., Widmer A.F.

Objectives:P. mendocina was first isolated in the 1970s from soil and water samples collected in the province of Mendoza, Argentina [1]. The first clinical case report was reported in 1992 with P. mendocina endocarditis, followed by two further case-reports of infections due to this organism. However, the association with human infections is largely unknown. We report a cluster of P. mendocina in diagnostic stem cell-cultures of the haematology unit.

Methods: We initiated an outbreak-investigation after the detection of Gram-negative bacteria by routine-microscopy of 21 diagnostic stem cell-cultures.

Identification of the Gram-negative bacteria was performed by conventional culture and additional confirmation by sequencing of 16s rDNA. Pulsed-field gel electrophoresis (PFGE) was performed to reveal the identity of the strains. For source-investigation environmental cultures of the involved surfaces in the affected laboratory, as well as water samples and the unopened fresh reagents used for the preparation of the diagnostic stem cell-cultures were examined.

Results: Culture and identification of the Gram-negative bacteria of three contaminated stem cell-cultures revealed P. mendocina. The environmental cultures and the water samples were negative for this pathogen. Culture of one of the reagents used however also revealed P. mendocina. PFGE revealed that the strains isolated were identical (Figure). Further outbreak investigation of the manufacturer confirmed contamination of their product. The computerized database of the clinical microbiology unit revealed that this pathogen has never been isolated before at our hospital in the last decade.

Conclusions: This is the first report of an outbreak caused by P. mendocina. We conclude that this environmental pathogen has the potential to cause contamination of reagents used in clinical settings. Our report demonstrates that commercial sterile product may be a source of outbreaks. During the entire outbreak no clinical isolate with P. mendocina was identified, nor was there evidence for an unusual increase of other Pseudomonas infections.


1. Palleroni, N. J., M. Doudoroff, and R. Y. Stainer. Taxonomy of the aerobic Pseudomonas: the properties of the Pseudomonas stutzeri group. J. Gen. Microbiol. 1970; 60:215–231.

Session Details

Date: 10/04/2010
Time: 00:00-00:00
Session name: Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases
Location: Vienna, Austria, 10 - 13 April 2010
Presentation type:
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