Journal List > Korean J Lab Med > v.27(3) > 1011394

Ahn, Yu, Jang, Kim, Park, Moon, and Park: Pseudo-outbreak of Stenotrophomonas maltophilia Due to Contamination of Bronchoscope

Abstract

Background

We noticed an abrupt increase in the isolation of Stenotrophomonas maltophilia from bronchoalveolar lavage (BAL) specimens collected at Chosun University Hospital. We performed surveillance cultures in order to identify the source of what appeared to be a pseudo-outbreak.

Methods

To investigate a possible nosocomial outbreak of S. maltophilia, we performed culture of 11 environmental specimens obtained from a bronchoscopy room and two bronchoscopes. Pulsed-field gel electrophoresis (PFGE) was used to examine the genetic relatedness among the strains of S. maltophilia recovered from BAL specimens of 3 patients and 1 environmental sample, as well as 9 unrelated strains of S. maltophilia as a control.

Results

During a 7 day-period in March 2006, S. maltophilia was isolated from the BAL specimens of 7 of 13 (54%) patients, compared to only 5 of 188 (2.6%) patients during the 6-month period prior to that period. S. maltophilia was isolated from 1 of the 11 environmental samples, which was obtained from a fiberoptic bronchoscope suction channel. All 7 patient isolates and one environmental isolate exhibited similar antibiotic susceptibility patterns. PFGE analysis of the genomic DNA from epidemic strains demonstrated an identical banding pattern, whereas each of epidemiologically unrelated strains showed a unique electrophoretic pattern.

Conclusions

Apparently one of the hospital bronchoscopes became contaminated with S. maltophilia during a bronchoscopic procedure. It is likely that subsequent specimen contamination occurred because the bronchoscope had been inadequately cleaned and disinfected. The pseudo-outbreak was controlled successfully by removing the source of infection.

References

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Fig. 1.
Incidence of S. maltophilia isolation from September 2005 to May 2006.
kjlm-27-205f1.tif
Fig. 2.
PFGE analysis of S. maltophilia isolates. Chromosomal DNA was digested with XbaI. Lane M, DNA molecular marker; lane 1 to 3, pseudo-outbreak isolates; lane 4, environmental isolate; lane 5 to 13, non-outbreak isolates.
kjlm-27-205f2.tif
Table 1.
Clinical features exhibited by the 7 patients whose bronchoalveolar lavage specimens yielded S. maltophilia
No. Case Age Sex Ward Hospital days Underlying disease Antimicrobial therapy Outcome
1 61 M Respiratory 3 Pneumonia + Not improved
2 82 M Respiratory 47 Lung cancer, TB + Expired
3 68 M Respiratory 12 Lung cancer + Not improved
4 63 M Respiratory 16 Pneumonia + Improved
5 72 M Respiratory 10 Pneumonia, DM + Improved
6 61 M Respiratory 15 Lung cancer Improved
7 49 M Outpatient 0 Hodgkin's lymphoma Not improved

Abbreviations: TB, tuberculosis; DM, diabetes mellitus; M, male.

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