Isabel N. de Kantor

Nosocomial Spread of Human Immunodeficiency Virus-Related Multidrug-Resistant Tuberculosis in Buenos Aires

A steep upsurge of human immunodeficiency virus (HIV)-associated multidrug-resistant tuberculosis (MDR-TB) was recently observed at a referral treatment center in Buenos Aires City. Between January 1994 and June 1995, TB isolates resistant to at least five drugs were recovered from 101 of 272 HIV-infected inpatients. Highly resistant isolates from 77 patients underwent restriction fragment length polymorphism study with IS6110. After cross-contamination was eliminated, a single TB strain was found to have caused disease in 68 patients with a history of on-site exposure. The frequency of smear-positive pulmonary disease was higher among these patients than among non-MDR-TB HIV-infected patients (50/68 vs. 60/148, P < .001), and the 1-year survival was dramatically reduced (5/68 vs. 92/148). The strain involved in the outbreak was traced back to patients hospitalized in 1992. Institutional infection control policies were and may still be inadequate to contain the spread of TB among immunodepressed subjects, as is the case in other large urban hospitals in Argentina.

Detection of circulating antibodies to purified protein derivative by enzyme-linked immunosorbent assay: its potential for the rapid diagnosis of tuberculosis.

An enzyme-linked immunosorbent assay for detecting antibodies to purified protein derivative was evaluated as a rapid method for serodiagnosis of childhood tuberculosis. Its specificity for IgG antibodies was 0.98 as determined in 55 sera from nontuberculous children who showed no significant effect of previous Bacillus Calmette-Guérin vaccination on the production of specific antibodies. Results were negative in 29 of 33 (87.9%) tuberculin-positive children and in 18 of 20 (90.0%) contacts, none of whom had evidence of tuberculosis. The sensitivity of this test was 0.51 as determined in 49 sera from bacteriologically confirmed cases; 17 of 27 smear positive cases and 8 of 22 children with positive cultures were detected. Results were positive in 32 of 114 (28.1%) patients with a diagnosis of tuberculosis not confirmed by microbiology. Consequently whereas a negative result does not rule out tuberculosis, a positive result is a strong indication of the disease. The IgM antibody determination yielded much less discriminative results.

Tuberculosis Laboratory Procedures for Developing Countries

Two of the main requirements for a successful National Tuberculosis Program (NTP) in developing countries have been clearly defined (1): 1. Government commitment to a tuberculosis (TB) program aiming at nationwide coverage, conceived as a permanent health system activity, integrated into the existing health structure with effective technical leadership from a central unit 2. Case detection and treatment follow-up based on bacteriological examinations Tuberculosis bacteriology—a fundamental element of the NTP—must interrelate closely with the administrative, epidemiological, and clinical components of the program. Bacteriological diagnostic services must be developed concurrently with the other activities of the NTP and should be integrated in the general health services of the country to attain maximum coverage (2).

Simultaneous Detection of Mycobacterium bovis and Mycobacterium tuberculosis in Human Cerebrospinal Fluid

In the April 2006 issue of the Journal of Clinical Microbiology , Shah et al. reported the simultaneous presence of Mycobacterium tuberculosis and Mycobacterium bovis in 22 human cerebrospinal fluid specimens ([5][1]). The method used to reveal the alleged coinfection was a novel nested PCR (N-PCR)

Culture of Mycobacterium tuberculosis from non-fixed sputum smears

Smears prepared from sputum species were kept in the dark at 4 degrees C or at 20-25 degrees C. Cultures for mycobacteria were carried out on these smears 0, 4, 8, and 15 days later and the results compared with those of cultures made from the sputum specimen on the day of collection. The percentage of negative cultures from originally positive specimens was high, and use of the method is not considered advisable. There is an additional risk of infection for laboratory staff when handling unfixed smears.