October 1, 2002
In a 1,700-bed hospital that serves a population of 630,000 in Madrid, Spain, the authors reviewed the records of the mycobateriology laboratory from January 1, 1988, to December 31, 1999. All patients with 1 or more isolates of M tuberculosis in different respiratory clinical samples were considered. The authors considered patients with recurrent episodes, i.e. those with new isolates of M tuberculosis separated by more than 100 days from the primary episode. In patients selected with recurrent episodes, the authors collected information regarding sex, age, HIV status, TB therapy, duration of treatment, time between episodes, and physicians' opinion regarding individual adherence to therapy.
Overall, 172 patients had at least a second episode of TB more than 100 days apart. Ninety-two M tuberculosis sequential isolates from 43 patients with more than 1 episode were available for analysis. All the 92 strains were typed by spoligotyping. Forty-six different spoliogotypes were obtained for the whole analysis group. Of the 43 patients, 10 (23 percent) showed different strains for the first and second episodes, meaning reinfection was the cause of their recurrences. A second molecular typing method was performed for the 33 patients whose sequential isolates were considered indistinguishable. For 29 of the 33 patients identical strains were confirmed. The remaining four had different strains. If the data are taken together, reinfection was found in 14 (33 percent) of the 43 patients analyzed. Reactivations involving the same strain were found in the remaining 29 (67 percent) of the 43 patients.
For the reinfection and reactivation groups, there were no significant differences according to HIV status or to other risk factors, such as adherence to TB therapy, intravenous drug abuse, alcoholism, homelessness, or prison stay. The antimicrobial susceptibility of the strains involved in reinfection remained unchanged (drug susceptible) in all patients but three. Two of these acquired resistance and in one reinfection was caused by a more susceptible strain than the one from the primary episode.
Archives of Internal Medicine
09.09.02; Vol. 162; No. 16: P. 1873-1879; Dario Garcia de Viedman, Ph.D.; Mercedes Marin, Pharm.D., Ph.D.; Susan Hernangómez, M.D.; Marisol Diaz, Pharm.D., Ph.D.; Maria Jesús Ruiz Serrano, Pharm.D.; Luis Alcalá, Pharm.D.; Emilio Bouza, M.D., Ph.D.