Objectives, To determine risk factors for antibiotic resistance in pat
ients with pulmonary, tuberculosis in four Health Jurisdictions of the
state of Chiapas. Material and Methods, A case-control study was carr
ied out in patients diagnosed by acid fast smear during 1992. A questi
onnaire was applied which included variables related to the diagnosis,
treatment and follow-up of the patients. Sputum samples were collecte
d for culture and sensitivity bests. A case of drug-resistant pulmonar
y tuberculosis was defined as the presence of culture colonies showing
resistance to one OF. 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 individu
als reported to have positive cultures, 13 (72.2 %) were resistent 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 resi
stance encountered in this patient population were monotherapy (OR = 3
4.2), abandonment of treatment (OR = 6.86), a prolonged period of illn
ess (OR = 6.40), delay in diagnosis and a history of prior therapy (OR
= 28.3). Conclusions. The high proportion of patients resistant to an
tituberculosis therapy poses a public health problem and is a clear co
nsequence of the problems arising from inadequate treatment.