Rapid detection and differentiation of mycobacterial species using a multiplex PCR system

Abstract

Introduction:The early diagnosis of mycobacterial infections is a critical step for initiating treatment and curing the patient. Molecular analytical methods have led to considerable improvements in the speed and accuracy of mycobacteria detection. Methods: The purpose of this study was to evaluate a multiplex polymerase chain reaction system using mycobacterial strains as an auxiliary tool in the differential diagnosis of tuberculosis and diseases caused by nontuberculous mycobacteria (NTM) Results: Forty mycobacterial strains isolated from pulmonary and extrapulmonary origin specimens from 37 patients diagnosed with tuberculosis were processed. Using phenotypic and biochemical characteristics of the 40 mycobacteria isolated in LJ medium, 57.5% (n=23) were characterized as the Mycobacterium tuberculosis complex (MTBC) and 20% (n=8) as nontuberculous mycobacteria (NTM), with 22.5% (n=9) of the results being inconclusive. When the results of the phenotypic and biochemical tests in 30 strains of mycobacteria were compared with the results of the multiplex PCR, there was 100% concordance in the identifi cation of the MTBC and NTM species, respectively. A total of 32.5% (n=13) of the samples in multiplex PCR exhibited a molecular pattern consistent with NTM, thus disagreeing with the fi nal diagnosis from the attending physician. Conclusions: Multiplex PCR can be used as a differential method for determining TB infections caused by NTM a valuable tool in reducing the time necessary to make clinical diagnoses and begin treatment. It is also useful for identifying species that were previously not identifi able using conventional biochemical and phenotypic techniques.

Diagnosis of mycobacterial infections based on acid-fast bacilli test and bacterial growth time and implications on treatment and disease outcome

“…The identification of M. tuberculosis infections in 63.6 % (35/55) of samples is consistent with other studies that found a higher prevalence of MTB; 67 % [ 26 ], 57.5 % [ 27 ], 78.6 % [ 28 ] and 77 % [ 29 ]. Despite the higher occurrence of MTB, it has been shown elsewhere that the MTB frequency is declining over the years, while the NTM frequency is significantly increased, with prevalence ranging from 9.1 % in 2003 to 31.9 % in 2009 [ 28 ].…”

Surgical treatment for chronic cervical lymphadenitis in children. Experience from a tertiary care paediatric centre on non-tuberculous mycobacterial infections

“…Moreover, the natural history of the disease leads to a longer time to diagnosis compared to acute bacterial adenitis. In fact, the persistence of the lymphadenitis is usually the reason for referring to a tertiary care centre, when a median delay of 8-12 weeks is commonly reported in 44% of cases before specialist evaluation [19,46], with a maximum interval between cervical lymphadenitis appearance to definitive treatment reported to be up to one year [41,47]. In the present study the mean interval between symptoms onset and final diagnosis was of 7 Fig.…”

Análisis de la mortalidad por tuberculosis en la ciudad de Medellín, año 2012

“…Esto implica una demora en el inicio del tratamiento que pudo haber afectado el resultado clínico. En ese sentido, la utilización de pruebas rápidas como las de biología molecular (ya disponibles en nuestro medio), puede agilizar el diagnóstico y, por ende, disminuir la mortalidad (23,24). En nuestra serie, el método molecular fue el único estudio que permitió el diagnóstico en 5,3 % de los casos; sin embargo, a la gran mayoría de pacientes no se les hizo este tipo de pruebas, muy probablemente por falta de conocimiento sobre su disponibilidad y por su costo excesivo en el país.…”