Low sensitivity of polymerase chain reaction for diagnosis of tuberculous meningitis in southeastern Brazil

Abstract

Two polymerase chain reaction (PCR) protocols showed low sensitivity (36% and 53% for TB AMPLICOR and MPB64 nested PCR, respectively), when compared with classic microbiological methods (73% and 54% for Ziehl-Neelsen staining and culture, respectively), in the diagnosis of tuberculous meningitis in 91 patients in southeastern Brazil. Only three PCR-positive, microbiologically negative patients were found. Analysis of sequential cerebrospinal fluid samples by nested PCR detected Mycobacterium tuberculosis DNA up to 29 days after the introduction of antituberculosis chemotherapy. Key-words: Diagnosis of tuberculous meningitis. PCR. Mycobacterium tuberculosis.Resumo Dois protocolos de reação em cadeia da polimerase (PCR) apresentaram baixa sensibilidade (36% e 53%, respectivamente), para TB AMPLICOR e PCR aninhado baseado no gene MPB64), quando comparados aos métodos microbiológicos clássicos (73% e 54% respectivamente para baciloscopia e cultura), no diagnóstico de meningite tuberculosa em 91 pacientes do sudeste do Brasil. Somente três pacientes apresentaram PCR positiva e microbiologia negativa. A análise de amostras seqüenciais de líquor com a PCR aninhada detectou DNA de Mycobacterium tuberculosis até 29 dias após a introdução de tratamento. Palavras-chaves: Diagnóstico da meningite tuberculosa. PCR. Mycobacterium tuberculosis.

The Diagnostic Utility of Bact/ALERT and Nested PCR in the Diagnosis of Tuberculous Meningitis

“…AP staining, though it has been claimed to be more sensitive than the ZN staining [15], in the present study, we could notice no significant differences. The sensitivity of the culture on the LJ medium (3.22%) was similar to that which was found in various other studies (2-8%) [13][14] . This could be due to the pacibacillary nature of the CSF (the minimum detection threshold being 10-100 bacilli per ml) or due to the presence of dead bacilli [8].…”

“…A high bacterial load (>10 4 -10 5 bacilli/ml) is needed in the specimen, to render an AFB microscopy result positive [5]. Various studies documented similar sensitivities of the smear microscopy for TBM, which ranged from 0-20% [2,[13][14]. AP staining, though it has been claimed to be more sensitive than the ZN staining [15], in the present study, we could notice no significant differences.…”

“…In a study which was done at AIIMS, India, by Ahuja et al, who had formulated this criterion, the sensitivities which were documented were 85.71%, 75% and 33.33% in the highly probable, probable and the possible subgroups respectively [9]. Brienze et al, had reported sensitivities of 53%, 50%, 7% and 8% in the confirmed, highly probable, probable and the possible subgroups respectively [13]. The differences in the sensitivities could be due to the use of the MBP 64 nested PCR.…”

Central Nervous System Tuberculosis: Pathogenesis and Clinical Aspects

“…These assays have been evaluated specifically in HIV-coinfected patients (59,180) and also as a means to monitor therapy (180,210). While many of those studies demonstrated improved sensitivity over traditional smear and culture methods, several other studies highlighted the low sensitivities associated with these PCR assays (25,68,112,164,206). Looking at the utility of applying PCR assays to the (206).…”

Comparación de adenosina deaminasa y detección de anticuerpos anti-antígeno A60 para el diagnóstico de meningitis tuberculosa

“…El rendimiento diagnóstico de IgM anti-A60 (sensibilidad de 94,1% y especificidad de 80,4%) resultó incluso superior a lo reportado en numerosos estudios para la RPC de M. tuberculosis en LCR 3,6,23 . Este hallazgo pudiese explicarse por la gran antigenicidad de M. tuberculosis que resulta en la producción de anticuerpos detectables mediante ELISA pese a que la carga misma de antígenos micobacterianos sea muy baja en la muestra de LCR 8,24 .…”