Chlamydia trachomatis serotype A infections in the Amazon region of Brazil: prevalence, entry and dissemination

INTRODUCTION: Chlamydia infection is associated with debilitating human diseases including trachoma, pneumonia, coronary heart disease and urogenital diseases. Serotypes of C. trachomatis show a fair correlation with the group of diseases they cause, and their distribution follows a well-described geographic pattern. Serotype A, a trachoma-associated strain, is known for its limited dissemination in the Middle East and Northern Africa. However, knowledge on the spread of bacteria from the genus Chlamydia as well as the distribution of serotypes in Brazil is quite limited. METHODS: Blood samples of 1,710 individuals from ten human population groups in the Amazon region of Brazil were examined for antibodies to Chlamydia using indirect immunofluorescence and microimmunofluorescence assays. RESULTS: The prevalence of antibodies to Chlamydia ranged from 23.9% (Wayana-Apalai) to 90.7% (Awa-Guaja) with a mean prevalence of 50.2%. Seroreactivity was detected to C. pneumoniae and to all serotypes of C. trachomatis tested; furthermore, we report clear evidence of the as-yet-undescribed occurrence of serotype A of C. trachomatis. CONCLUSIONS: Specific seroreactivity not only accounts for the large extent of dissemination of C. trachomatis in the Amazon region of Brazil but also shows an expanded area of occurrence of serotype A outside the epidemiological settings previously described. Furthermore, these data suggest possible routes of Chlamydia introduction into the Amazon region from the massive human migration that occurred during the 1,700s. .

Nested-PCR do gene que codifica o antígeno b aplicada ao diagnóstico da tuberculose pulmonar / Nested-PCR for gene that encodes the antigen b applied to the diagnosis of pulmonary tuberculosis

A reação em cadeia da polimerase usada para amplificação de uma seqüência interna de um fragmento previamente amplificado (nested-PCR) foi investigada como uma alternativa complementar a pesquisa de bacilos álcool ácido resistentes e a cultura do Mycobacterium tuberculosis em meio de Lowenstein-Jensen. Foram investigadas 144 amostras de escarro de pacientes suspeitos de tuberculose encaminhados ao Laboratório de Tuberculose do Instituto Evandro Chagas em Belém, no período de junho de 2002 a dezembro de 2003. Das 144 amostras, 121 foram caracterizadas como tuberculose, 119 foram positivas na cultura, 95 na baciloscopia e 128 na nested-PCR. A sensibilidade da nested-PCR foi 96 por cento (116/121), enquanto a especificidade foi 48 por cento (11/23). A nested-PCR poderá ser uma ferramenta complementar para o diagnóstico da tuberculose, pois apresenta sensibilidade equivalente à cultura, no entanto, necessita de maiores avaliações visando minimizar o número de resultados falso-positivos.

The polymerase chain reaction used for amplifying an internal sequence of a previously amplified fragment (nested-PCR) was investigated as a complementary alternative for searching for alcohol-acid resistant bacilli and Mycobacterium tuberculosis cultures in Lowenstein-Jensen medium. 144 sputum samples were investigated from patients with suspected tuberculosis that were sent to the Tuberculosis Laboratory of the Evandro Chagas Institute in Belém, between June 2002 and December 2003. From the 144 samples, 121 were characterized as tuberculosis: 119 were positive in cultures, 95 under bacilloscopy and 128 using nested-PCR. The sensibility of the nested-PCR was 96 percent (116/121), while the specificity was 48 percent (11/23). Nested-PCR may be a complementary tool for diagnosing tuberculosis, since it presents sensitivity equivalent to that of cultures. However, further evaluations are needed with the aim of minimizing the number of false-positive results.

Diagnóstico molecular da tuberculose pulmonar / Molecular diagnosis of pulmonary tuberculosis

A reação em cadeia da polimerase (PCR) e suas variações, como a nested-PCR, têm sido destacadas como técnicas moleculares promissoras para o diagnóstico rápido da tuberculose (TB). No presente estudo avaliou-se a nested-PCR utilizando-se como marcadores moleculares a seqüência IS6110 e o antígeno b aplicados ao diagnóstico da TB. Foram submetidas a baciloscopia, cultura e nested-PCR 136 amostras clínicas de pacientes com suspeita de TB. O diagnóstico de tuberculose pulmonar foi atribuído a 116 pacientes e, desses, 97 foram multibacilares e 111 apresentaram cultura positiva para M. tuberculosis. As reações de nested-PCR identificaram 70 por cento (antígeno b) e 94 por cento (IS6110) dos casos paucibacilares. Os valores de sensibilidade determinados para cultura, nested-PCR do IS6110 e antígeno b foram 95 por cento, 98 por cento e 86 por cento, respectivamente. A especificidade foi de 100 por cento, 15 por cento e 45 por cento para cultura, nested-PCR do IS6110 e antígeno b, respectivamente. O diagnóstico molecular da tuberculose deve estar fundamentado na análise conjunta de vários parâmetros, como baciloscopia, cultura, manifestações clínicas, prova terapêutica e história prévia de tuberculose.

Chain reaction of polimerase (PCR) and its variations such as the nested-PCR have been outstanding as promising molecular techniques for the fast diagnosis of the tuberculosis (TB). In the present study the nested-PCR was evaluated using as molecular markers the sequence IS6110 and the antigen b applied to the diagnosis of TB. One hundred and thirty six clinical samples of patients with suspicion of TB were submitted to the baciloscopia, culture and nested-PCR. The diagnosis of pulmonary tuberculosis was attributed to 116 patients, of these, 97 were multi-bacilli and 111 presented positive culture for M. tuberculosis. The nested-PCR reactions identified 70 percent (antigen b) and 94 percent (IS6110) of the acid-fast smear negative cases of tuberculosis. The sensibility values determined for culture, and nested-PCR of IS6110 and antigen b were 95 percent, 98 percent and 86 percent, respectively. The specificity was 100 percent, 15 percent and 45 percent for culture, nested-PCR of IS6110 and antigen b, respectively. The molecular diagnosis of the tuberculosis should be based in the combined analysis of several parameters, as the baciloscopia, culture, clinical manifestations, therapeutic proves and previous history of tuberculosis.