Inadequate treatment regimens and poor compliance have led to increased rates of drug resistance in Mycobacterium tuberculosis around the world, leading to the emergence of multidrug resistant (MDR) and extensively drug resistant (XDR) strains. In Peru MDR-TB rates are amongst the highest in the world and XDR-TB cases have been reported for almost a decade. Drug susceptibility tests detect cases with resistant strains, providing the best treatment option to the patient and diminishing the spread of the disease. This review is directed at the non-specialist physician, focusing upon the drug susceptibility tests approved by the National TB Program of Peru and others currently still under research.

Inadequate treatment regimens and poor compliance have led to increased rates of drug resistance in Mycobacterium tuberculosis around the world, leading to the emergence of multidrug resistant (MDR) and extensively drug resistant (XDR) strains. In Peru MDR-TB rates are amongst the highest in the world and XDR-TB cases have been reported for almost a decade. Drug susceptibility tests detect cases with resistant strains, providing the best treatment option to the patient and diminishing the spread of the disease. This review is directed at the non-specialist physician, focusing upon the drug susceptibility tests approved by the National TB Program of Peru and others currently still under research.

Tuberculosis (TB) is an infectious disease primarily of humans which produces high morbidity and mortality. Dogs are also susceptible to Mycobacterium tuberculosis infections; therefore, the present study searched for evidence of the presence of this pathogen in 58 dogs that live with human pulmonary TB patients in Lima, Peru. Chest Xray was performed and pharyngeal swab, saliva, bronchial fluid, urine and feces samples were taken from dogs. Fluorescence microscopy was performed with auramine O staining and TB culture by the Löwenstein Jensen and the Microscopic Observation Drug Susceptibility (MODS) methods. Epidemiological data was collected to define the patient-pet relationship. The custom of spitting on the floor of the house, the dog licking patient’s sputum and the affective contact with the pet were practices identified during the study that might facilitate the transmission o...

La tuberculosis (TB) es una enfermedad infecciosa en el humano, con alta morbilidad y mortalidad. Los caninos son también susceptibles a infecciones por Mycobacterium tuberculosis, de allí que el presente estudio buscó evidenciar la presencia de la micobacteria en 58 caninos que conviven con pacientes con TB pulmonar en Lima, Perú. Se tomaron placas radiográficas de tórax y muestras de hisopado faríngeo, saliva, fluido bronquial, orina y heces de los caninos. Se utilizó microscopía fluorescente con tinción auramina O, cultivo Löwenstein Jensen y se aplicó la metodología MODS (Sensibilidad a Drogas por Observación Microscópica). Se recolectó información epidemiológica para definir la relación paciente-mascota. La costumbre de esputar en el piso de la casa, el lamido del esputo del paciente por el can y el contacto afectivo con la mascota fueron prácticas encontradas qu...

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Most culture-based methods for tuberculosis diagnosis remain low-cost options for low- and mid-income countries. The MODS culture is a rapid and low-cost assay to diagnose tuberculosis and determine drug susceptibility. However, its implementation is limited due to the low accessibility to supplies required for the enriched medium. In this study, we evaluate two alternative culture media: A powder-based mixed (PM) and a lyophilized media (LM). Catalase, PANTA, and gamma irradiation were evaluated as additions to PM and LM. The culture performance of the alternative media was compared with the standard MODS medium (MM) using Mycobacterium tuberculosis isolates and positive acid-fast smear sputum samples. Overall, no significant difference was observed in the bacterial growth between PM and LM with MM. However, PANTA and gamma irradiation combined reduced bacterial growth significantly in ...

La mayoría de los métodos basados en cultivos para el diagnóstico de la tuberculosis siguen siendo opciones de bajo costo para los países de ingresos bajos y medianos. El cultivo MODS es un ensayo rápido y de bajo costo para diagnosticar la tuberculosis y determinar la susceptibilidad a los medicamentos. Sin embargo, su implementación está limitada debido a la baja accesibilidad a los suministros requeridos para el medio enriquecido. En este estudio, evaluamos dos medios de cultivo alternativos: un medio mixto en polvo (PM) y un medio liofilizado (LM). Se evaluaron la catalasa, el PANTA y la irradiación gamma como adiciones a los medios PM y LM. El rendimiento del cultivo de los medios alternativos se comparó con el medio MODS estándar (MM) utilizando aislados de Mycobacterium tuberculosis y muestras de esputo con baciloscopía positiva. En general, no se observó una diferenci...

Background: Tuberculosis (TB) is a communicable, preventable and curable disease caused by the bacterium Mycobacterium tuberculosis (MTB). Peru is amongst the 30 countries with the highest burden of multidrug-resistant tuberculosis (MDR-TB) worldwide. In the fight against drug-resistant tuberculosis, the UKMYC6 microdilution plate was developed and validated by the CRyPTIC project. The objective of the study was to evaluate the use of the broth microdilution (BMD) plate methodology for susceptibility testing of drug-resistant MTB strains in Peru. Methods: MTB strains isolated between 2015 and 2018 in Peru were used. 496 nationally-representative strains determined as drug-resistant by the routine 7H10 Agar Proportion Method (APM) were included in the present study. The Minimum Inhibitory Concentration (MIC) of 13 antituberculosis drugs were determined for each strain using the UKMYC6 mic...

Tuberculosis phenotypic detection assays are commonly used in low-resource countries. Therefore, reliable detection methods are crucial for early diagnosis and treatment. The microscopic observation drug susceptibility (MODS) assay is a culture-based test to detect Mycobacterium tuberculosis and characterize drug resistance in 7–10 days directly from sputum. The use of MODS is limited by the availability of supplies necessary for preparing the enriched culture. In this study, we evaluated three dry culture media that are easier to produce and cheaper than the standard one used in MODS [1]: an unsterilized powder-based mixed (Boldú et al., 2007) [2], a sterile-lyophilized medium, and (Sengstake et al., 2017) [3] an irradiated powder-based mixed. Mycobacterial growth and drug susceptibility were evaluated for rifampin, isoniazid, and pyrazinamide (PZA). The alternative cultures were eva...

Los ensayos fenotípicos de detección de tuberculosis son comúnmente utilizados en países con bajos recursos. Por lo tanto, los métodos de detección confiables son cruciales para el diagnóstico y tratamiento temprano. El ensayo de susceptibilidad a los fármacos por observación microscópica (MODS) es una prueba basada en cultivo para detectar Mycobacterium tuberculosis y caracterizar la resistencia a los medicamentos en 7-10 días directamente a partir del esputo. El uso de MODS está limitado por la disponibilidad de suministros necesarios para preparar el cultivo enriquecido. En este estudio, evaluamos tres medios de cultivo secos que son más fáciles de producir y más baratos que el estándar utilizado en MODS [1]: una mezcla en polvo no esterilizada (Boldú et al., 2007) [2], un medio estéril liofilizado y (Sengstake et al., 2017) [3] una mezcla en polvo irradiada. Se eval...

Whole Genome Sequencing (WGS) is a promising tool in the global fight against tuberculosis (TB). The aim of this study was to evaluate the use of WGS in routine conditions for detection of drug resistance markers and transmission clusters in a multidrug-resistant TB hot-spot area in Peru. For this, 140 drug-resistant Mycobacterium tuberculosis strains from Lima and Callao were prospectively selected and processed through routine (GenoType MTBDRsl and BACTEC MGIT) and WGS workflows, simultaneously. Resistance was determined in accordance with the World Health Organization mutation catalogue. Agreements between WGS and BACTEC results were calculated for rifampicin, isoniazid, pyrazinamide, moxifloxacin, levofloxacin, amikacin and capreomycin. Transmission clusters were determined using different cut-off values of Single Nucleotide Polymorphism differences. 100% (140/140) of strains had val...

Introduction: Cough is a key symptom of tuberculosis (TB) as well as the main cause of transmission. However, a recent literature review found that cough frequency (number of coughs per hour) in patients with TB has only been studied once, in 1969. The main aim of this study is to describe cough frequency patterns before and after the start of TB treatment and to determine baseline factors that affect cough frequency in these patients. Secondarily, we will evaluate the correlation between cough frequency and TB microbiological resolution. Methods: This study will select participants with culture confirmed TB from 2 tertiary hospitals in Lima, Peru. We estimated that a sample size of 107 patients was sufficient to detect clinically significant changes in cough frequency. Participants will initially be evaluated through questionnaires, radiology, microscopic observation drug susceptibility...