Epidemiology of tuberculosis on Gran Canaria: a 4 year population study using traditional and molecular approaches.

BACKGROUND: In recent years several population based studies using restriction fragment length polymorphism (RFLP) analysis have shown a higher rate of recent transmission of tuberculosis than previously thought. This study was undertaken to determine the transmission patterns of tuberculosis and the potential causes of recent transmission on the island of Gran Canaria (Spain). METHODS: The strains of all patients diagnosed with tuberculosis confirmed by culture between 1 January 1993 and 31 December 1996 were typed by RFLP using the insertion sequence IS6110. A cluster was defined as two or more isolates with an identical RFLP pattern. Epidemiological linkage through contact tracing was investigated. RESULTS: Of the total of 719 patients, 153 (21.3%) were excluded because there was inadequate bacterial DNA for genotyping (n=129) or the isolates of Mycobacterium tuberculosis had less than five copies of IS6110 (n=24). The isolates from 409 patients (72.3%) were grouped into 78 different clusters with an estimated 58.5% of the cases being due to recent transmission. Young age was the only significant predictor of clustering. Only in 147 (35.9%) of the 409 patients belonging to a cluster could an epidemiological link be found. 111 patients (19.6%) were identified as having had previous contact with a tuberculosis patient and 81 of them (72.9%) belonged to a cluster. The three largest clusters included 75, 49 and 20 patients, respectively. CONCLUSION: Recent transmission is frequent among patients with tuberculosis on Gran Canaria and could be associated with certain aspects of control measures. Some of the clusters described in the study could be due to the prevalence of particular strains of M tuberculosis on the island.

Epidemiological evidence of the spread of a Mycobacterium tuberculosis strain of the Beijing genotype on Gran Canaria Island.

Molecular epidemiological studies suggest that particular Mycobacterium tuberculosis strains have an enhanced capacity to spread within a community. One strain, the Beijing genotype, has been associated with outbreaks in a number of communities throughout the world. IS6110 restriction fragment length polymorphism (RFLP) analysis was performed on M. tuberculosis isolates from 566 of the 721 patients (78.5%) diagnosed with tuberculosis (TB) on Gran Canaria Island from 1993 to 1996, as well as 35% of isolates from 1991-1992 (85 strains). RFLP identification of the family of strains of the Beijing genotype was confirmed by spoligotyping. Medical records of all patients were reviewed and epidemiological links were identified. Of 566 M. tuberculosis isolates from 1993 to 1996 with RFLP available, 72% belonged to clusters. The largest contained 75 cases and was caused by a strain of the Beijing genotype that was introduced to the island in 1993. It was found in 10 patients in 1993 (5.5%), 12 in 1994 (8.1%), 18 in 1995 (16.4%), and 35 in 1996 (27.1%). Epidemiological linkage was confirmed for 68% of cases. This study has demonstrated rapid dissemination of this strain of the Beijing genotype. This genotype might play an important role in the future of the worldwide tuberculosis epidemic.

Exogenous reinfection with tuberculosis on a European island with a moderate incidence of disease.

The frequency and determinants of exogenous reinfection and of endogenous reactivation of tuberculosis in patients previously treated are poorly understood. In Gran Canaria Island, Spain, between 1991 and 1996, 962 tuberculosis cases were confirmed by culture. Drug susceptibility testing was performed on available bacterial isolates and IS6110-based RFLP genotyping was carried out. Twenty-three patients (2.4%) had two positive cultures separated by at least 12 mo, 18 of whom had bacterial DNA available for genotypic analysis. The initial and final isolates from eight (44%) were different genotypes, indicating exogenous reinfection. Six of them were retreated after cure and two retreated after default. Six were HIV seronegative and two were HIV seropositive. Endogenous reactivation was seen in the remaining 10 patients of whom eight were retreated after default and two after cure. Three of the eight (38%) being retreated after default developed multidrug resistance. One genotype was responsible for a second episode of tuberculosis in five cases, three exogenous reinfections and two endogenous reactivations. In the context of a moderate incidence of tuberculosis, exogenous reinfection is an important cause of TB recurrence, even in HIV-seronegative patients.

[Usefulness of detecting Mycobacterium tuberculosis by genome amplification in the diagnosis of childhood pulmonary tuberculosis]. / Utilidad de la detección de Mycobacterium tuberculosis mediante amplificación genómica en el diagnóstico de la tuberculosis pulmonar en la infancia.

OBJECTIVE: To evaluate the polymerase chain reaction in the diagnosis of pulmonary tuberculosis in children. PATIENTS AND METHODS: 135 samples (68 sputum and 67 gastric aspirates) of 72 patients under 15 years old with suspected tuberculosis and a negative acid-fast stain were included in the study. In all the samples an acid-fast stain and culture in Lowestein-Jensen with and without piruvate were performed. Also, a specific detection of Mycobacterium tuberculosis complex (MT) was made by PCR (Amplicor-MT-Roche Diagnostic). Tuberculosis was certainly diagnosed when M. tuberculosis was isolated or clinical evidence of tuberculosis in positive-PCR cases with negative culture was achieved. RESULTS: Ten samples of six patients were positive culture. Four of these samples were positive PCR. In addition, two samples of two patients with negative culture were positive PCR. Both patients had a clinical diagnosis of pulmonary tuberculosis with effective anti-tuberculosis treatment, one of them had also another positive PCR and culture sample. The results of sensitivity, specificity, positive predictive value and negative predictive value by patient according to the reference methodology were 57.1, 100, 100 and 95.4%, respectively, and by sample 66.6%, 100, 100 and 96.8%, respectively. Other 15 patients presented pulmonary tuberculosis with negative PCR and culture; so the sensitivity of the culture and the PCR regarding a clinical diagnosis were 27.3% (6/22) and 18% (4/22) respectively. CONCLUSION: Due to the diagnosis by culture takes a long time and the low percentage of samples of pediatric patients with positive acid-fast rain stain, the PCR would be useful in order to achieve quickly and specific diagnosis of tuberculosis in a high-prevalence population.

[Microbiological study of vulvovaginitis in premenarcheal girls]. / Estudio microbiológico de vulvovaginitis en niñas prepúberes.

BACKGROUND: A prospective microbiological study of the vaginal swab specimens from premenarcheal girls with clinical diagnosis of vulvovaginitis was done from the 1st of September 1991 to the 31st of August 1994. PATIENTS AND METHODS: Vaginal secretions from premenarcheal girls with clinical findings were examined. Most important pathogenic agents were investigated and if there was an inflammatory reaction in the Gram stain and a heavy growth on culture, other potentially pathogenic agents were considered also. RESULTS: In 70 (28.7%) of the 262 patients a potentially pathogenic microorganism was found: eight cases (3.0%) due to Streptococcus pyogenes, four cases (1.5%) due to Candida albicans. Only in one case Neisseria gonorrhoeae was isolated. Among the uncertain etiologic agents, Haemophilus influenzae was the most frequently isolated (7.6%). In 25 (12.6%) of the 198 patients Enterobius vermicularis ova were visualized. CONCLUSIONS: Streptococcus pyogenes was the most frequently related organism with the vulvovaginitis syndrome among the traditionally established pathogens. The role of Haemophilus influenzae should be considered due to the high prevalence of isolation in this group of patients. We consider that differential diagnosis with Enterobius vermicularis infestation should be done in all cases.

[Disseminated infection by Mycobacterium scrofulaceum: apropos of 3 cases]. / Infección diseminada por Mycobacterium scrofulaceum: a propósito de 3 casos.

BACKGROUND: Mycobacterium avium-M. Intracellulare complex and Mycobacterium kansasii cause most of nontuberculous mycobacteria infections in AIDS patients in Spain. Mycobacterium scrofulaceum is rarely isolated as a cause of disseminated disease and most of case have been reported before the AIDS occurrence. METHODS: Three clinical cases of patients with disseminated disease caused by M.scrofulaceum and AIDS are reviewed. RESULTS: Clinical presentation in all cases was similar to those of other disseminated mycobacterial infection, and was also linked to severe immunosuppression (CD4 cell count < 100 CD4/mm3). CONCLUSIONS: In our area, M. scrofulaceum is the second species of nontuberculous mycobacteria causing disseminated disease in AIDS patients. The most frequent species is M. avium-M. intracellulare complex. For diagnosis an AIDS patient complaining of febrile syndrome without foci and severe immunosuppression, is mandatory to obtain blood cultures and biopsy or adenopathy aspirates if present. To our knowledge, these are the first reports in our country.