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Probable laboratory contamination of clinical specimens with Leptospira meyeri
Nobuo Koizumi1, Hiroki Kawabata, Haruo Watanabe
1Department of Bacteriology, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo 162-8640, Japan.
Abstract:
Leptospira meyeri were isolated from the blood or the pleural effusion cultures of four patients at a commercial clinical laboratory. All isolates were identical in their 16S rDNA sequences and NotI or SfiI restriction profiles of the chromosome DNA on pulsed-field gel electrophoresis. However, intraperitoneal inoculation of the isolate (NIID1) failed to kill hamsters and none of the patients' sera reacted with L. meyeri strains isolated, indicating leptospiral contamination occurred during laboratory investigation.
Insights
Leptospira meyeri was isolated from patients, but laboratory contamination was suspected. Further testing confirmed contamination, as the bacteria did not cause illness in hamsters or react with patient sera.
Area of Science:
- Microbiology
- Clinical Diagnostics
- Bacteriology
Background:
- Leptospira species are pathogenic bacteria causing leptospirosis.
- Accurate identification of Leptospira in clinical samples is crucial for diagnosis and treatment.
Purpose of the Study:
- To investigate the identity and pathogenicity of Leptospira meyeri isolates from clinical samples.
- To determine if the isolates represented a true infection or laboratory contamination.
Main Methods:
- Bacterial isolation from blood and pleural effusion cultures.
- 16S rDNA sequencing for genetic identification.
- Pulsed-field gel electrophoresis (PFGE) with NotI and SfiI restriction enzymes for DNA profiling.
- Intraperitoneal inoculation of isolates into hamsters to assess pathogenicity.
- Serological testing of patient sera against isolated L. meyeri strains.
Main Results:
- Four patients yielded Leptospira meyeri isolates.
- All isolates shared identical 16S rDNA sequences and PFGE profiles.
- Isolate NIID1 did not cause mortality in hamsters.
- Patient sera did not react with the isolated L. meyeri strains.
Conclusions:
- The identical genetic profiles suggest a common source for the isolates.
- The lack of pathogenicity in hamsters and absence of serological reaction indicate laboratory contamination.
- This highlights the importance of rigorous contamination control in clinical microbiology laboratories.