Journal List > Korean J Clin Microbiol > v.11(1) > 1038149

Korean J Clin Microbiol. 2008 Apr;11(1):5-10. Korean.
Published online April 30, 2008.
Copyright © 2008 The Korean Society of Clinical Microbiology
Pseudo-outbreak of Klebsiella oxytoca from Bronchial Washing Specimens
Ja Young Lee,1 Jeong Hwan Shin,1,2 Hyun-Kyung Lee,3 Seong-Mi Yu,5 Eun Hee Park,6 Hee Ryune Lee,1 Jae Hyen Kim,1 Hye Ran Kim,1 Chi Sook Moon,3 Young Jae Kim,4 and Jeong Nyeo Lee1,2
1Department of Laboratory Medicine, College of Medicine, Inje University, Busan, Korea.
2Paik Institute for Clinical Research, College of Medicine, Inje University, Busan, Korea.
3Department of Internal Medicine, College of Medicine, Inje University, Busan, Korea.
4Department of Anesthesiology, College of Medicine, Inje University, Busan, Korea.
5Department of Nursing, Gwangju Health College, Gwangju, Korea.
6Busan Metropolitan City Institute of Health and Environment, Busan, Korea

Correspondence: Jeong Hwan Shin, Department of Laboratory Medicine, Busan Paik Hospital, College of Medicine, Inje University, 633-165, Gaegeum-dong, Busanjin-gu, Busan 614-735, Korea. (Tel) 82-51-890-6475, (Fax) 82-51-893-1562, Email:
Received November 19, 2007; Accepted January 16, 2008.



We noticed a sudden increase in the isolation of Klebsiella oxytoca from bronchial washing specimens during May to June 2006. An epidemiological investigation was conducted to identify the cause of the outbreak and to implement appropriate infection control measures.


A total of 18 isolates of K. oxytoca were found. The 14 bronchial washing specimens that yielded K. oxytoca were taken in the outpatient bronchoscopy suite, and the other 4 specimens were obtained by a portable bronchoscopy. The medical records and microbiologic findings of these patients were reviewed. Environmental samples from two bronchoscopes and the bronchoscopy suite were cultured. The relations between the available 10 isolates from bronchial washing fluid were investigated by pulsed-field gel electrophoresis (PFGE).


No patients were judged to have had true infections attributable to K. oxytoca either before or after bronchoscopy. Cultures of samples from two bronchoscopes and related environment did not grow K. oxytoca. The PFGE analysis showed that 8 of 10 isolates had a similar pattern of DNA fragments. An infection control strategy was implemented, including adequately cleaning and disinfecting the bronchoscopes, and a sharp reduction in the incidence of K. oxytoca from bronchial washing samples followed.


The sudden increase of K. oxytoca from bronchial washing specimens was a pseudo-outbreak. We presumed that the bronchoscopes became contaminated during a procedure in a patient colonized with K. oxytoca in the upper-respiratory tract.

Keywords: Klebsiella oxytoca; Psuedo-outbreak; Bronchial washing; Pulsed-field gel electrophoresis


Fig. 1
Pulsed-field gel electrophoresis patterns of K. oxytoca isolates from bronchial washings.
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Fig. 2
Epidemic curve of K. oxytoca isolates from bronchial washing samples collected during May and June. Solid bars, number of isolates related to the outbreak determined by PFGE analysis; striped bars, number of isolates unrelated to the outbreak determined by PFGE; open bars, number of isolates unavailable for PFGE.
Click for larger image


Table 1
Patient characteristics and the dates of the bronchial washing cultures that grew K. oxytoca
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