PCR colorimetric dot-blot assay and clinical pretest probability for diagnosis of Pulmonary Tuberculosis in Smear-Negative patients

<p>Abstract</p> <p>Background</p> <p>Smear-negative pulmonary tuberculosis (SNPTB) accounts for 30% of Pulmonary Tuberculosis (PTB) cases reported annually in developing nations. Polymerase chain reaction (PCR) may provide an alternative for the rapid detection of <it>Mycobacterium tuberculosis </it>(MTB); however little data are available regarding the clinical utility of PCR in SNPTB, in a setting with a high burden of TB/HIV co-infection.</p> <p>Methods</p> <p>To evaluate the performance of the PCR dot-blot in parallel with pretest probability (Clinical Suspicion) in patients suspected of having SNPTB, a prospective study of 213 individuals with clinical and radiological suspicion of SNPTB was carried out from May 2003 to May 2004, in a TB/HIV reference hospital. Respiratory specialists estimated the pretest probability of active disease into high, intermediate, low categories. Expectorated sputum was examined by direct microscopy (Ziehl-Neelsen staining), culture (Lowenstein Jensen) and PCR dot-blot. Gold standard was based on culture positivity combined with the clinical definition of PTB.</p> <p>Results</p> <p>In smear-negative and HIV subjects, active PTB was diagnosed in 28.4% (43/151) and 42.2% (19/45), respectively. In the high, intermediate and low pretest probability categories active PTB was diagnosed in 67.4% (31/46), 24% (6/25), 7.5% (6/80), respectively. PCR had sensitivity of 65% (CI 95%: 50%–78%) and specificity of 83% (CI 95%: 75%–89%). There was no difference in the sensitivity of PCR in relation to HIV status. PCR sensitivity and specificity among non-previously TB treated and those treated in the past were, respectively: 69%, 43%, 85% and 80%. The high pretest probability, when used as a diagnostic test, had sensitivity of 72% (CI 95%:57%–84%) and specificity of 86% (CI 95%:78%–92%). Using the PCR dot-blot in parallel with high pretest probability as a diagnostic test, sensitivity, specificity, positive and negative predictive values were: 90%, 71%, 75%, and 88%, respectively. Among non-previously TB treated and HIV subjects, this approach had sensitivity, specificity, positive and negative predictive values of 91%, 79%, 81%, 90%, and 90%, 65%, 72%, 88%, respectively.</p> <p>Conclusion</p> <p>PCR dot-blot associated with a high clinical suspicion may provide an important contribution to the diagnosis of SNPTB mainly in patients that have not been previously treated attended at a TB/HIV reference hospital.</p

Tempo de reação simples auditivo e visual em surfistas com diferentes níveis de habilidade: comparação entre atletas profissionais, amadores e praticantes Auditory and visual single reaction span in surfers with different ability levels: comparison of professional, amateur athletes and surf practitioners

O tempo de reação simples (TRS) representa o nível de coordenação neuromuscular, no qual os estímulos visuais, auditivos ou táteis são decodificados pelo corpo através de diferentes processos físico-químicos e mecânicos. O objetivo desta pesquisa foi identificar os TRS auditivo e visual em surfistas profissionais, amadores e praticantes, verificar se existem diferenças estatísticas entre os grupos de surfistas e correlacionar os tempos de reação com a performance dos atletas. Participaram deste estudo 103 surfistas: 42 atletas profissionais do sexo masculino (brasileiros e estrangeiros), 11 atletas profissionais do sexo feminino, 25 atletas amadores universitários e 25 praticantes de surfe. A coleta de dados foi realizada nas praias onde aconteceram os respectivos eventos, WQS (World Qualifyng Series, etapa do circuito mundial), Superfsurf (etapa do campeonato brasileiro de surfe profissional), CCSU (etapa do circuito catarinense de surfe universitário). Foram utilizados como instrumentação um interruptor com uma tecla de sensibilidade de 0,8N, um LED para estímulo visual, duas caixas acústicas, com 315Hz de freqüência e 81dB de pressão sonora, para estímulo auditivo e um dispositivo eletrônico com a finalidade de gerar o sinal auditivo, visual e de sincronismo. A aquisição dos dados foi realizada utilizando o software SAD versão 32. Foram encontradas diferenças estatisticamente significativas para os TRS auditivo e visual entre os profissionais (masculinos) versus praticantes, profissionais (femininos) versus praticantes. Entre os amadores versus praticantes foram encontradas diferenças estatisticamente significativas apenas para o TRS visual, com TRS menores para os mais experientes. Uma correlação positiva foi encontrada para o TRS visual entre os profissionais (femininos) versus no ranking.<br>The reaction span RS (RTS) represents the level of neuromuscular coordination in which the visual, auditory or touch stimuli are decodified by the body through different physical- chemical and mechanical processes. The aim of this research was to identify the auditory and visual RTS in professional and amateur surfers as well as surf practitioners to verify whether there are statistical differences among the surfers groups as well as to correlate the reaction span with the athletes' performance. 103 surfers participated in this study: 42 professional male athletes (Brazilian and foreign); 11 professional female athletes; 25 amateur college student athletes, and 25 surf practitioners. Data collection was conducted at the beaches where the following events took place: WQS (World Qualifying Series, world circuit phase); Supersurf (Professional Surfing Brazilian championship phase); CCSU (catarinense college surf circuit phase). The following instruments were used: a switch with a button of 0.8 (N) sensibility; a L.E.D. for visual stimulus; two loudspeakers with 315 (Hz) of frequency and 81 (db) of sound pressure for auditory stimulus, as well as an electronic device with the aim to generate the auditory, visual and synchronism signal. The data acquisition was performed with the use of the SAD software version 32. Statistically significant differences were found for the auditory and visual RTS between the professional (male) versus practitioners and professional (female) versus practitioners. Statistically significant differences were found between the amateurs versus practitioners only for the visual RTS, with lower RTS for the more experienced ones. A positive correlation was found for the visual RTS between the professional (female) athletes versus the ranking