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Evaluation of direct detection of Mycobacterium tuberculosis rifampin resistance by a nitrate reductase assay applied to sputum samples in Cotonou, Benin
No full textThe aim of this study was to evaluate a nitrate reductase assay (NRA) performed on smear-positive sputa for the direct detection of rifampin resistance in Mycobacterium tuberculosis. A total of 213 smear-positive sputa with a positivity score of 1+ or more (>1 acid-fast bacillus per field by fluorescence microscopy) were used in the study. The samples were decontaminated using the modified Petroff method, and portions of the resulting suspension were used to perform the NRA. The NRA results were compared with the reference indirect proportion method for 177 specimens for which comparable results were available. NRA results were obtained at day 10 for 15 specimens (9%), results for 88 specimens (50%) were obtained at day 14, results for 66 specimens (37%) were obtained at day 18, and results for the remaining 8 specimens (4%) were obtained at day 28. Thus, 96% of NRA results were obtained in 18 days. Of the 177 specimens, there was only one discrepancy (susceptible according to the NRA and resistant according to the indirect proportion method). NRA is simple to perform and provides a rapid, accurate, and cost-effective means for the detection of rifampin resistance in M. tuberculosis isolates
Vaginal microbicides can interfere with nucleic acid amplification tests used for the diagnosis of Chlamydia trachomatis and Neisseria gonorrhoeae infection
No full textWe confirmed findings from previous studies that cellulose sulfate gel can interfere with nucleic acid amplification tests used for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae. We therefore recommend that the effects of microbicide gels on diagnostic assays of sexually transmitted infections be established before starting up clinical studies
Dissecting the neutralizing antibody specificities of broadly neutralizing sera from human immunodeficiency virus type 1-infected donors
No full textAttempts to elicit broadly neutralizing antibody responses by human immunodeficiency virus type 1 (HIV-1) vaccine antigens have been met with limited success. To better understand the requirements for cross-neutralization of HIV-1, we have characterized the neutralizing antibody specificities present in the sera of three asymptomatic individuals exhibiting broad neutralization. Two individuals were infected with clade B viruses and the third with a clade A virus. The broadly neutralizing activity could be exclusively assigned to the protein A-reactive immunoglobulin G (IgG) fraction of all three donor sera. Neutralization inhibition assays performed with a panel of linear peptides corresponding to the third hypervariable (V3) loop of gp120 failed to inhibit serum neutralization of a panel of HIV-1 viruses. The sera also failed to neutralize chimeric simian immunodeficiency virus (SIV) and HIV-2 viruses displaying highly conserved gp41-neutralizing epitopes, suggesting that antibodies directed against these epitopes likely do not account for the broad neutralizing activity observed. Polyclonal IgG was fractionated on recombinant monomeric clade B gp120, and the neutralization capacities of the gp120-depleted samples were compared to that of the original polyclonal IgG. We found that the gp120-binding antibody population mediated neutralization of some isolates, but not all. Overall, the data suggest that broad neutralization results from more than one specificity in the sera but that the number of these specificities is likely small. The most likely epitope recognized by the monomeric gp120 binding neutralizing fraction is the CD4 binding site, although other epitopes, such as the glycan shield, cannot be excluded
Survival of Mycobacterium ulcerans at 37°C
No full textThe definitive version is available at www3.interscience.wiley.comBone infection and metastatic spread in cases of Buruli ulcer imply that Mycobacterium ulcerans is able to survive and multiply at 37 degrees C. This study investigated the survival at 37 degrees C of M. ulcerans isolates from diverse geographical and clinical sources. Although the viability of all isolates decreased after a few days at 37 degrees C, viable bacilli remained after 13 days at 37 degrees C in most instances. African isolates of M. ulcerans were more thermotolerant than isolates from temperate regions. Isolates from skin and bone lesions of the same patients showed no difference in thermotolerance
Buruli ulcer surveillance, Benin, 2003-2005
No full textWe reviewed Buruli ulcer (BU) surveillance in Benin, using the World Health Organization BU02 form. We report results of reliable routine data collected on 2,598 new and recurrent cases from 2003 through 2005
Inhibition of replication of primary HIV-1 isolates in huPBL-NOD/Scid mice by antibodies from HIV-1 infected patients
No full textAlthough a limited number of HIV-infected patients have broadly neutralizing antibodies, it has not been examined whether these antibodies can protect against infection with primary virus in vivo. Here we screened the plasma of 23 HIV-1-infected patients for broadly neutralizing antibodies. Purified antibodies from subjects with broad and more narrow responses were administered to huPBL-NOD/Scid mice that were subsequently challenged with primary viruses of clade A, B and CRF01_AE. Although we observed a lack of correlation between the data from the in vitro neutralization assay and the results from the passive immunization experiments, we report for the first time that antibodies from HIV-infected persons can inhibit replication of primary virus isolates in an animal model
Validation of candidate smear microscope quality indicators, extracted from tuberculosis laboratory registers
No full textSETTING: Kinshasa Province, Democratic Republic of Congo. OBJECTIVE: To identify and validate register-based indicators of acid-fast bacilli (AFB) microscopy quality. DESIGN: Selection of laboratories based on reliability and variation in routine smear rechecking results. Calculation of relative sensitivity (RS) compared to recheckers and its correlation coefficient (R) with candidate indicators based on a fully probabilistic analysis incorporating vague prior information using WinBUGS. RESULTS: The proportion of positive follow-up smears correlated well (median R 0.81, 95% credibility interval [CI] 0.58-0.93), and the proportion of first smear-positive cases fairly (median R 0.70, 95% CI 0.38-0.89) with RS. The proportions of both positive suspect and low positive case smears showed poor correlations (median R 0.27 and -0.22, respectively, with ranges including zero). CONCLUSIONS: The proportion of positives in follow-up smears is the most promising indicator of AFB smear sensitivity, while the proportion of positive suspects may be more indicative of accessibility and suspect selection. Both can be obtained from simple reports, and should be used for internal and external monitoring and as guidance for supervision. As proportion of low positive suspect smears and consistency within case series are more difficult to interpret, they should be used only on-site by laboratory professionals. All indicators require more research to define their optimal range in various settings
Human T-lymphotropic virus 1: recent knowledge about an ancient infection
No full textHuman T-lymphotropic virus 1 (HTLV-1) has infected human beings for thousands of years, but knowledge about the infection and its pathogenesis is only recently emerging. The virus can be transmitted from mother to child, through sexual contact, and through contaminated blood products. There are areas in Japan, sub-Saharan Africa, the Caribbean, and South America where more than 1% of the general population is infected. Although the majority of HTLV-1 carriers remain asymptomatic, the virus is associated with severe diseases that can be subdivided into three categories: neoplastic diseases (adult T-cell leukaemia/lymphoma), inflammatory syndromes (HTLV-1-associated myelopathy/tropical spastic paraparesis and uveitis among others), and opportunistic infections (including Strongyloides stercoralis hyperinfection and others). The understanding of the interaction between virus and host response has improved markedly, but there are still no clear surrogate markers for prognosis and there are few treatment options
Clinical and histologic features of skin lesions in a cynomolgus monkey experimentally infected with Mycobacterium ulcerans (Buruli ulcer) by intradermal inoculation
No full textBuruli ulcer, caused by Mycobacterium ulcerans, is a destructive infection that most commonly affects the skin. Animal models for Buruli ulcer include guinea pigs, rats, mice, and armadillos, but each is limited in replicating the spectrum of human disease. Here, a cynomolgus monkey was infected with two concentrations of M. ulcerans (1.0 and 2.2 x 10(8)) by intradermal inoculation, 3 months apart. All injection sites developed papules that progressed to ulcers with undermined borders within 2-4 weeks. The rate of progression and size of the ulcers were proportional to the numbers of organisms inoculated. Biopsies from ulcer edges showed ulceration, robust inflammatory cell infiltrates, granulomatous-like responses, mild edema, and extracellular acid-fast bacilli. The ulcers healed spontaneously between Weeks 8 and 12, with no signs of systemic infection. This report, the first to describe a non-human primate experimentally infected with M. ulcerans, suggests that cynomolgus monkeys are modestly susceptible and develop some of the clinical and histologic features of Buruli ulcer