State-of-the-art detection of Mycobacterium tuberculosis in blood during tuberculosis infection using phage technology.

Tuberculosis (TB), an aerosol-transmitted infection caused by Mycobacterium tuberculosis (Mtb), remains the commonest cause of death globally, from an infectious bacterial disease. Nine years on from the launch of the World Health Organization (WHO)'s END-TB strategy, disease incidence rates are stubbornly unchanged [1]. While this represents, in part, a reversal of improving trends caused by the COVID-19 pandemic, it also reflects the fragility and inadequacy of healthcare systems to sustain TB control [2]. Although multifactorial, a key reason for this is the ineffectiveness of existing clinical tools to meet the two key objectives of the END-TB strategy-(i) early diagnosis and treatment of TB disease (to limit onward transmission); and (ii) disease prevention through screening for asymptomatic TB infection (TBI). Meeting both objectives will rely on the development of new biomarkers with high accuracy, but the global nature of the TB problem also requires that new tests are rapid, low cost and can be measured in patients by sampling from universally accessible sites. In this review, we will present the accumulating evidence for circulating Mtb in both TB disease and asymptomatic TBI and discuss the potential utility of novel bacteriophage-based technology for blood-based detection of Mtb.

Phage amplification assay as rapid method for Salmonella detection

The application of rapid methods is crucial for the HACCP program implantation in food industry. In this context, Phage Amplification Assay is a good candidate because is based on the interactions of phage and their host bacteria. This method using phage P22 was applied with to detect Salmonella cells in chicken breast. Samples of 25 g of chicken breast were diluted and the appropriate dilutions were used in phage amplification assay for Salmonella detection. After 3-4 h of incubation, it was observed a phage titre of approximately 10(4) pfu mL-1, indicating that there were Salmonella cells which were naturally present in the meat. The presence of Salmonella cells were verified by using direct plating on XLD agar and by conventional enrichment procedure. The colonies suspected to be Salmonella were serologically tested and were identified as belonging to the serogroups B (S. typhimurium group) and D (S. enteritidis group). It can be concluded that this method provides a rapid and alternative application for Salmonella detection in food samples reducing both time and laboratory work to 3-4 hours.

A aplicação de métodos rápidos é crucial para a implantação de programas de HACCP em indústrias de alimentos. Neste contexto, o método de amplificação de bacteriófagos é um instrumento de diagnóstico importante porque está baseado na interação dos bacteriófagos com suas células hospedeiras. Este método, usando o bacteriófago P22, foi aplicado para detectar Salmonella em peito de frango. Amostras de 25 g de peito de frango foram diluídas e as diluições apropriadas foram usadas no método de amplificação de bacteriófagos na detecção de Salmonella. Após 3-4 horas de incubação, foi observado uma titulação de partículas virais de, aproximadamente, 10(4) ufp mL-1 (unidades formadoras de placas virais), indicando a presença de células de Salmonella na carne de frango. A comprovação da presença de Salmonella neste produto foi verificada usando-se plaqueamento direto em ágar XLD e procedimento de enriquecimento convencional. As colônias suspeitas de Salmonella foram sorologicamente testadas e identificadas como pertencendo aos sorogrupos B (grupo de S. typhimurium) e D (grupo de S. enteritidis). Portanto, concluiu-se que este método pode ser aplicado, na detecção de Salmonella em alimentos, porque fornece rápido e conclusivo resultado, reduzindo o tempo de análise e o trabalho laboratorial para 3-4 horas.