- NEW YORK (Reuters
Health) - A substantial proportion of tuberculosis cases in Mexico are
resistant to treatment with the antibiotics isoniazid and rifampin, key
drugs used to combat the lung infection.
- The findings suggest that a strategy used to reduce tuberculosis
(TB) cases in other countries -- called directly observed treatment, or
short-course DOTS -- may not be adequate to control multi-drug resistant
TB, according to two studies in the March 13th issue of the Archives of
Internal Medicine. In DOTS, healthcare workers observe patients as they
take their medicine. Left alone, many people with tuberculosis fail to
take all their medication and contribute to the spread of drug-resistant
- In one study, Dr. Jordan W. Tappero of the Centers for
Disease Control and Prevention in Atlanta, Georgia, and colleagues tested
bacteria isolated from 460 TB patients for signs of drug resistance.
- Of the samples, 13% of the new cases of TB and 51% of
the retreatment cases showed resistance to either one or more of the TB
drugs used as first line defense in Mexico -- isoniazid, rifampin and pyrazinamide.
Multi-drug resistant bacteria was observed in 2% of the new cases and 22%
of the retreatment cases.
- ``Our results reveal substantial levels of drug resistance''
in this population, the investigators note.
- The researchers suggest that ``expanding the DOTS program
to the entire country, considering the adoption of a four-drug treatment
regimen for patients with no history of treatment, and the development
of a national strategy to treat patients with multi-drug-resistant TB are
important actions to limit drug resistance.''
- However, Dr. Maria de Lourdes Garcia-Garcia of Avenida
Universidad in Cuernavaca, Mexico, and colleagues say that the results
of their study may imply ``that although the widespread implementation
of DOTS is likely to be essential for TB control, in regions with high
rates of drug resistance, it may not be sufficient.''
- In a study of 238 patients, Garcia-Garcia and colleagues
found resistance in 28% of the patients, and multi-drug resistance in 11%
of the patients.
- After DOTS therapy, 75% of the patients were cured, 9%
failed, and 4% died.
- ``Drug resistance was a strong independent risk factor
for treatment failure,'' Garcia-Garcia and colleagues report.
- The studies ``highlight key challenges to a global strategy
for tuberculosis control,'' according to an editorial by Dr. Donald A.
Enarson of the International Union Against Tuberculosis and Lung Disease
(IUATLD) in Paris, France.
- Neither Mexico nor any of the other countries with drug
resistance 'hot spots' are correctly following IUATLD's recommendations
for implementing DOTS, and this may be the reason why the high rate of
resistant strains were seen in the Mexican studies, he said. SOURCE: Archives
of Internal Medicine 2000;160:581-582, 630-636, 639-644.
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