Annals of Clinical Microbiology, The official Journal of the Korean Society of Clinical Microbiology


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pISSN 2288-0585 eISSN 2288-6850

Pseudo-outbreak of Klebsiella oxytoca from Bronchial Washing Specimens

Original article

Annals of Clinical Microbiology (Ann Clin Microbiol) 2008 April Volume 11, Issue 1, pages 29-34.

Pseudo-outbreak of Klebsiella oxytoca from Bronchial Washing Specimens

Ja Young Lee1, Jeong Hwan Shin1,2, Hyun-Kyung Lee3, Seong-Mi Yu5, Eun Hee Park6, Hee Ryune Lee1, Jae Hyen Kim1, Hye Ran Kim1, Chi Sook Moon3, Young Jae Kim4, Jeong Nyeo Lee1,2
1Department of Laboratory Medicine, 2Paik Institute for Clinical Research, Departments of 3Internal Medicine and 4Anesthesiology, College of Medicine, Inje University, Busan; 5Department of Nursing, Gwangju Health College, Gwangju; 6Busan Metropolitan City Institute of Health and Environment, Busan, Korea


Background: 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. 

Methods: 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). 

Results: 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. 

Conclusion: 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. (Korean J Clin Microbiol 2008;11:5-10)


Klebsiella oxytoca, Psuedo-outbreak, Bronchial washing, Pulsed-field gel electrophoresis