Microbial persistence in mycobacterial infections

J. Grosset, C. C. Guelpa-Lauras, H. Lecoeur

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In tuberculosis, microbial persistence as measured directly by lungs and spleen culture in the mouse or indirectly by the relapse rate in man was a major problem as long as streptomycin and isoniazid were the only bactericidal drugs in use. Since the advent of rifampicin (and pyrazinamide) microbial persistence is no longer a clinical problem. In all countries where rifampicin is routinely used for the treatment of tuberculosis, the relapse rate is almost nil although the patients are often treated on a purely ambulatory basis and the total length of treatment is reduced. Despite all the differences that exist between experimental tuberculosis in the mouse and tuberculosis in man, it is possible that in man as in the mouse stable healing does not necessarily mean real sterilization. Whatever the theoretical implications of this possibility, the goal of chemotherapy for tuberculosis is to obtain a definite cure of the patients and not necessarily the sterilization of the microbial population. In tuberculosis chemotherapy, the microbial persistence problem arose clearly only when the problem of acquired drug resistance had been solved by the use of combined drug regimens of active drugs. Before that time both problems were confused. It may be taken for granted that Mycobacterium leprae can persist despite long-term chemotherapy with dapsone, that dapsone alone gives rise to an increasing proportion of dapsone-resistant strains and that irregularities in the intake of drugs are usual in long-term chemotherapy. These three facts fit exactly with what was observed in tuberculosis before the advent of rifampicin. Since the advent of rifampicin, it may also be taken for granted that Mycobacterium leprae may persist despite long-term chemotherapy with rifampicin, that rifampicin alone gives rise to a proportion of rifampicin-resistant strains and that anarchic use of rifampicin will certainly lead to a disaster. Microbial persistence in leprosy might well differ from microbial persistence in tuberculosis. In tuberculosis only few organisms (between 1 and 100) can persist after prolonged chemotherapy. In leprosy the persisting organisms could be very numerous (about 106). Would microbial persistence in leprosy mean that the patient is not healed?

Original languageEnglish (US)
Pages (from-to)41-49
Number of pages9
JournalQuaderni di Cooperazione Sanitaria
VolumeNO. 1
StatePublished - Jan 1 1983
Externally publishedYes

ASJC Scopus subject areas

  • General Medicine

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