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The development of an accurate antigen detection assay for the diagnosis of active tuberculosis (TB) would represent a major clinical advance. Here, we demonstrate that the Mycobacterium tuberculosis Rv1681 protein is a biomarker for active TB with potential diagnostic utility. We initially identified, by mass spectroscopy, peptides from the Rv1681 protein in urine specimens from 4 patients with untreated active TB. Rabbit IgG anti-recombinant Rv1681 detected Rv1681 protein in lysates and culture filtrates of M. tuberculosis and immunoprecipitated it from pooled urine specimens from two TB patients. An enzyme-linked immunosorbent assay formatted with these antibodies detected Rv1681 protein in unconcentrated urine specimens from 11/25 (44%) TB patients and 1/21 (4.8%) subjects in whom TB was initially clinically suspected but then ruled out by conventional methods. Rv1681 protein was not detected in urine specimens from 10 subjects with Escherichia coli-positive urine cultures, 26 subjects with confirmed non-TB tropical diseases (11 with schistosomiasis, 5 with Chagas' disease, and 10 with cutaneous leishmaniasis), and 14 healthy subjects. These results provide strong validation of Rv1681 protein as a promising biomarker for TB diagnosis.T uberculosis (TB) remains the second most common cause of death from an infectious disease in the world. According to a 2012 World Health Organization (WHO) report, there were an estimated 8.7 million new cases of TB globally in 2011 and approximately 1.4 million TB-related deaths (430,000 of which involved HIV-positive individuals) (1). Failure to control the spread of TB is due in large part to failure to adequately detect (and thus to efficiently treat) infectious cases (2); therefore, a major focus of the WHO's global plan to stop TB (3) is the development of new simple and cost-effective diagnostic methods to improve case detection. Historically, culture of Mycobacterium tuberculosis from a clinical specimen has been the gold standard for TB diagnosis; however, it is expensive, time-consuming, and not available worldwide. Thus, in resource-limited settings, diagnosis of active TB relies primarily on clinical evaluation and, where available, microscopic evaluation of sputum specimens. Sputum smears have widely varying sensitivities in different settings (20 to 80%) and are of limited utility in paucibacillary (e.g., pediatric and HIVassociated) TB (3-5). Due to the lack of accessible and effective diagnostic methods, many patients in resource-limited settings are treated empirically based on clinical information alone, exposing some patients to unneeded and potentially toxic drugs and missing others who have active TB.The ideal diagnostic method for tuberculosis would be a lowcost, point-of-care (POC), rapid, simple, and accurate test that could distinguish individuals with active TB from those with latent disease or no infection (including Mycobacterium bovis BCGvaccinated individuals) (2, 6). We previously demonstrated the identification by mass spectroscopy (MS) of four ...

We evaluated the performance of the ELISA technique in the detection of IgA antibodies against different Mycobacterium tuberculosis antigenic preparations in serum samples from 49 patients with pulmonary tuberculosis collected before and after the start of specific treatment. The controls consisted of serum samples from healthy patients without any prior contact with the bacteria and serum samples from patients with other pneumopathies. Glycolipid antigen gave the best diagnostic performance, with a sensitivity of 88% and specificities varying from 88 to 100% in the control groups. These antigens constitute a powerful tool for the diagnosis and monitoring of patients with pulmonary tuberculosis.

Bacterial sepsis remains a major cause of mortality and blood cultures are the gold standard of laboratory diagnosis even though they lack sensitivity in neonates. Culturenegative sepsis, also known as clinical sepsis, has long been considered a diagnosis in neonatal intensive care units because, as well as culture-positive infants, culture-negative neonates have worse prognosis in comparison with non-infected ones. Quantitative amplifications are used to detect bacterial infections in neonates but results are considered only in a qualitative way (positive or negative). The aim of the present study was to determine and compare bacterial load levels in blood culture-positive and culture-negative neonatal sepsis. Seventy neonates with clinical and laboratory evidence of infection admitted at three neonatal intensive care units were classified as blood culture-positive or culture-negative. Blood samples obtained at the same time of blood cultures had bacterial load levels assessed through a 16S rDNA qPCR. Blood cultures were positive in 29 cases (41.4%) and qPCR in 64 (91.4%). In the 29 culture-positive cases, 100% were also positive by qPCR, while in the 41 culture-negative cases, 35 (85.4%) were positive by qPCR. Bacterial load levels were in general < 50 CFU/mL, but were significantly higher in culture-positive cases (Mann-Whitney, p = 0.013), although clinical and laboratory findings were similar, excepting for deaths. In conclusion, the present study has shown that blood culture-negative neonates have lower bacteria load levels in their bloodstream when compared to blood culture-positive infants.

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Parasite load in AF is associated with the clinical outcome in congenital toxoplasmosis, irrespective of gestational age at maternal infection.