Tuberculosis recurrences: reinfection plays a role in a population whose clinical/epidemiological characteristics do not favor reinfection.
BACKGROUND
Tuberculosis (TB) recurrences can be due to either reactivation by the same strain (standard assumption) or reinfection by a new strain. Reinfection has mainly been studied in selected populations with a high risk of reexposure to TB. Our aim was to analyze the role of reinfection in TB recurrences in unselected populations, without the clinical/epidemiological circumstances that favor the involvement of a new different strain of Mycobacterium tuberculosis in the recurrence.


METHODS
A molecular typing analysis was performed with 92 sequential isolates of M tuberculosis from 43 patients with recurrent TB, during a 12-year period. The subjects were both positive and negative for the human immunodeficiency virus, most did not adhere to anti-TB therapy, and they lived in an area with a moderate incidence of TB. Recurrence was considered as being caused by reinfection when the molecular fingerprints for the strains involved in the sequential episodes of TB were different.


RESULTS
In 14 (33%) of the 43 patients, different M tuberculosis strains were involved in the first and in subsequent episodes of TB. Reinfection was found for patients who were both positive and negative for the human immunodeficiency virus, and most patients did not adhere to anti-TB therapy. Differences between the reinfection and reactivation groups were not significant (P =.77) according to the time interval between episodes.


CONCLUSIONS
Reinfection plays an important role in recurrent TB in a population without the clinical/epidemiological circumstances that are usually assumed to favor it. Reinfection should, thus, be considered as a cause of TB recurrences in a wider context than before.
Servicio de Microbiología y Enfermedades Infecciosas, Hospital Gregorio Marañón, C/Dr Esquerdo 46, 28007 Madrid, Spain. dgviedma@microb.net
Darío
D
García de Viedma
Mercedes
M
Marín
Susana
S
Hernangómez
Marisol
M
Díaz
María Jesús
MJ
Ruiz Serrano
Luis
L
Alcalá
Emilio
E
Bouza
D000328:Adult; D015373:Bacterial Typing Techniques; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000032:analysis; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction; D015995:Prevalence; D012008:Recurrence; D013030:Spain / Q000453:epidemiology; D014397:Tuberculosis, Pulmonary / Q000453:epidemiology* / Q000517:prevention & control*
D004269:DNA, Bacterial