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Session 154
Poster Abstracts Tuberculosis and HIV Wednesday, 1:30 - 3:30 pm Hall B |
Background: Recent worldwide reports on nosocomial
transmission of multidrug-resistant tuberculosis (TB) strains have brought to
light the need for new methods to facilitate adequate early-stage strategies to
prevent further spread of the disease. We evaluated the clinical usefulness of
spoligotyping, a polymerase chain reaction-based method for simultaneous
detection and typing of Mycobacterium
tuberculosis strains.
Methods: A 2-year survey of
all suspected cases of TB observed between January 2000 and December 2001 was
conducted in a university-based TB control program. Spoligotyping was applied
to acid-fast bacilli-positive slides from biological specimens or from
mycobacterial cultures in liquid and on solid media. The sensitivity and
specificity of spoligotyping in distinguishing M. tuberculosis from non-tuberculous mycobacteria were calculated
in comparison with culture results. The sensitivity and specificity of
spoligotyping in typing M. tuberculosis
isolates were calculated in comparison with IS6110 clustering.
Results: Spoligotyping was performed on 350 samples,
obtained from 148 patients. Overall sensitivity and specificity for the
detection of M. tuberculosis complex
bacteria were 97% and 95% respectively, and the application directly to biological
specimens showed a sensitivity of 98% and a specificity of 96%. Laboratory
turnaround time of spoligotyping for slides obtained directly from biologic
material preceded culture identification by a median of 20 days. In comparison
with IS6110-based restriction
fragment length polymorphism typing, spoligotyping overestimated the number of
isolates with identical DNA fingerprints by about 50%, demonstrating, however,
a 100% negative predictive value. Identification and typing by means of
spoligotyping allowed us to correctly start with anti-mycobacterial treatment
in 31 cases and to modify ongoing treatment in nine other cases. In 11 cases
spoligotyping alone provided a useful result in establishing a correct therapy
in the absence of grown culture. In another case it was possible to identify
and treat a multidrug-resistant tuberculosis case in 6 days.
Conclusions: Spoligotyping’s
rapidity as a detection/typing method renders it useful in the outbreak
management of tuberculosis in a clinical setting.
Keywords: tuberculosis; multidrug resistance; molecular epidemiology
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