[False tuberculosis outbreak caused by specimen contamination in a micro-bacteriology laboratory: confirmation by molecular techniques].

BACKGROUND

The authors describe a false outbreak of tuberculosis by contamination in sample processing.

METHODS

The longitudinal polymorphisms of restriction fragments (RFLPs) of 6 strains of Mycobacterium tuberculosis isolated in different patients over a three week period and which were apparently implicated in an outbreak of tuberculosis were analyzed.

RESULTS

Four of the strains studied presented identical restriction pattern and the remaining two presented totally different patterns. Following study of the clinical histories and the epidemiologic relationships three cases of tuberculosis were confirmed. The other three strains isolated corresponded to contamination during the sampling process.

CONCLUSIONS

In a possible outbreak of six cases of tuberculosis, molecular techniques have allowed identification of three true cases of tuberculosis and have demonstrated contamination during the sampling process in three other cases. The latter could not have been shown with the clinical and phenotypical data of the strains.