[Risk factors for antitubercular drug resistance in Chiapas, Mexico].

OBJECTIVES

To determine risk factors for antibiotic resistance in patients with pulmonary tuberculosis in four Health Jurisdictions of the state of Chiapas.

MATERIAL AND METHODS

A case-control study was carried out in patients diagnosed by acid fast smear during 1992. A questionnaire was applied which included variables related to the diagnosis, treatment and follow-up of the patients. Sputum samples were collected for culture and sensitivity tests. A case of drug-resistant pulmonary tuberculosis was defined as the presence of culture colonies showing resistance to one or more drugs. The control group was patients with negative smears and cultures or positive cultures for M. tuberculosis sensitive to the specific drugs.

RESULTS

Of the total of 18 individuals reported to have positive cultures, 13 (72.2%) were resistant to one or more drugs. Resistance to two or more drugs was found in 10 of them of which three were resistant to five antituberculosis drugs. The most frequent resistance was to isoniazid (77%). Risk factors for resistance encountered in this patient population were monotherapy (OR = 34.2), abandonment of treatment (OR = 6.86), a prolonged period of illness (OR = 6.40), delay in diagnosis and a history of prior therapy (OR = 28.3).

CONCLUSIONS

The high proportion of patients resistant to antituberculosis therapy poses a public health problem and is a clear consequence of the problems arising from inadequate treatment.