Detection of Mycobacterium tuberculosis complex organisms in the stools of patients with pulmonary tuberculosis

Abstract

The laboratory diagnosis of pulmonary tuberculosis mainly relies on the detection of Mycobacterium tuberculosis complex (MTC) organisms in the sputum. In patients who do not give sputum, alternative respiratory tract specimens can be obtained only by invasive procedures. Based on the known survival of MTC organisms in the gastric fluid, we hypothesized that swallowed MTC organisms would be detectable in stool samples. We compared the presence of MTC organisms in respiratory tract specimens and stool specimens collected in parallel from the same patients. MTC was detected in cultures grown on egg-based medium after appropriate decontamination, by microscopic examination after Ziehl-Neelsen staining and by real-time PCR detection of IS6110 using internal controls. A case of pulmonary tuberculosis was defined by the presence of (i) clinical and radiological signs and symptoms suggestive of pulmonary tuberculosis, and (ii) culture of MTC organisms from at least one respiratory tract specimen or (iii) the presence of acid-fast bacilli in the sputum that were subsequently identified as MTC organisms by real-time PCR. The observation of 134 patients suspected to be suffering pulmonary tuberculosis led to the identification of 24 cases and 110 non-infected control patients. Cases and controls did not significantly differ with respect to sex but cases were significantly younger than controls. The sensitivity/specificity was 37.5 %/100 % for the microscopic examination of stools, 54.2 %/100 % for culturing and 100 %/97.3 % for real-time PCR. The positive predicted value was 100 %, 100 % and 88.9 %, respectively, and the negative predicted value was 88 %, 90.9 % and 100 %, respectively. In four patients, a stool specimen initially yielded the correct diagnosis of pulmonary tuberculosis before evaluation of the respiratory tract specimen confirmed the diagnosis. These data indicate that stools could be used in conjunction with sputum testing or as an alternative specimen upon which to base the diagnosis of pulmonary tuberculosis by molecular identification of acid-fast bacilli and culture. This non-invasive alternative procedure is of particular interest for patients who cannot expectorate. INTRODUCTIONPulmonary infection is the most prevalent form of tuberculosis (Saranchuk et al., 2007). Exposure to contact persons can cause secondary infection, and in some areas sustained high-level prevalence of this deadly infection (Johansen et al., 2002). The diagnosis of pulmonary tuberculosis currently relies upon the detection of Mycobacterium tuberculosis complex (MTC) organisms in sputum (Pfyffer, 2007). Some patients, however, are unable to produce sputum, including children (Oberhelman et al., 2006;Starke & Correa, 1995), immunocompromised patients and patients with neurological impairment (Andresen, 2007). In these situations, alternative specimens obtained by invasive procedures include nasopharyngeal aspirates (Owens et al., 2007), gastric aspirates (Chierakul et al., 2003), respiratory tract secretions obtained by bronchos...

Paradoxical conservation of a set of three cellulose-targeting genes in Mycobacterium tuberculosis complex organisms

“…M. bovis has been shown to be transmitted from bovine to bovine and from bovine to humans (Ashford et al, 2001) by the oral route, thus being potentially in close contact with cellulose-containing foodstuffs in the digestive tract of vertebrates such as mice (Boulahrouf et al, 1990) and pigs (Varel et al, 1984). Likewise, we have recently shown that living M. tuberculosis organisms can be detected in the stools of patients with pulmonary tuberculosis (El Khechine et al, 2009). M. bovis, however, is also efficiently transmitted directly by the aerosol route, being responsible for outbreaks of tuberculosis (Rodwell et al, 2008) and bovine tuberculosis (Wilkins et al, 2008).…”

The risk of tuberculosis transmission to free‐ranging great apes

“…The detection of fecal antibodies against pathogenic organisms has not been widely utilized for disease screening in primates; however, methods for fecal antibody detection have proven successful for the non-invasive detection of Simian Immunodeficiency virus and Simian Foamy virus in wild chimpanzees [Keele et al, 2009;Liu et al, 2008]. Given the development of a detectable humoral immune response to tuberculosis in primates, the detection of anti-tuberculosis antibodies in feces may be a feasible option for diagnosis [Lin et al, 2008;Lyashchenko Recent studies among humans with active pulmonary tuberculosis reveal approximately 50% sensitivity and 100% specificity for the detection of M. tuberculosis by stool culture, and even higher sensitivity using molecular detection (e.g., IS6110 PCR-RFLP) [Cordova et al, 2010;El Khéchine et al, 2009]. Therefore, culture and/or PCR may be a useful approach to pathogen detection in the feces of great apes.…”

A Novel Solid Medium for Culturing Mycobacterium tuberculosis Isolates from Clinical Specimens

“…(7,8). Seventy-one patients gave one specimen, 31 patients gave two specimens, 11 patients gave three specimens, five patients gave four specimens, three patients gave five, six, and seven specimens, and one patient gave 10 specimens.…”