Mycobacterium tuberculosis Cpn60.2 and DnaK Are Located on the Bacterial Surface,Where Cpn60.2 Facilitates Efficient Bacterial Association with Macrophages

Mycobacterium tuberculosis, the causative agent of tuberculosis, initially contacts host cells with elements of its outer cell wall, or capsule. We have shown that capsular material from the surface of M. tuberculosis competitively inhibits the nonopsonic binding of whole M. tuberculosis bacilli to macrophages in a dose-dependent manner that is not acting through a global inhibition of macrophage binding. We have further demonstrated that isolated M. tuberculosis capsular proteins mediate a major part of this inhibition. Two-dimensional polyacrylamide gel electrophoresis analysis of the capsular proteins showed the presence of a wide variety of protein species, including proportionately high levels of the Cpn60.2 (Hsp65, GroEL2) and DnaK (Hsp70) molecular chaperones. Both of these proteins were subsequently detected on the bacterial surface. To determine whether these molecular chaperones play a role in bacterial binding, recombinant Cpn60.2 and DnaK were tested for their ability to inhibit the association of M. tuberculosis bacilli with macrophages. We found that recombinant Cpn60.2 can inhibit ∼57% of bacterial association with macrophages, while DnaK was not inhibitory at comparable concentrations. Additionally, when polyclonal F(ab′)₂ fragments of anti-Cpn60.2 and anti-DnaK were used to mask the surface presentation of these molecular chaperones, a binding reduction of ∼34% was seen for anti-Cpn60.2 F(ab′)₂, while anti-DnaK F(ab′)₂ did not significantly reduce bacterial association with macrophages. Thus, our findings suggest that while M. tuberculosis displays both surface-associated Cpn60.2 and DnaK, only Cpn60.2 demonstrates adhesin functionality with regard to macrophage interaction.The initiation of a tuberculous infection involves the adherence and phagocytosis of Mycobacterium tuberculosis bacilli by host cells. It is generally thought that the primary host niche of M. tuberculosis is the alveolar macrophage (Mφ). To access this cell, ligands on the outer surface of the M. tuberculosis bacillus must come in contact with surface receptors of the Mφ. Although a significant amount of information concerning the Mφ receptors involved in this interaction is available (15, 71), the identities of the mycobacterial cell surface components that mediate this binding are less well understood. However, evidence for the involvement of mycobacterial lipoarabinomannans (57), capsular polysaccharides (8), glycopeptidolipids (72), 19-kDa antigen (9), mycotin (21), and Apa glycoprotein (47) has been reported previously.For any of the aforementioned moieties to be involved in the binding of mycobacteria to host cells, they would have to be located on the surface of the bacterium. Early reports suggested that the outer surface of mycobacteria was composed of mycosides (10, 11). Later studies indicated the presence of an outer polysaccharide-rich layer (45, 50), which could explain the presence of the so-called electron-transparent zone often seen in electron micrographs of mycobacteria inside Mφ (13, 18) and more recently in axenically grown bacteria (17, 42, 43, 51). Support for this contention has come from studies describing the presence of an outer surface capsule on M. tuberculosis (12). Carbohydrates make up 85% of the capsule, and the predominant sugar is glucan (approximately 70% of all sugars present). Arabinomannan and mannan are also present in significant quantities, as are a number of proteins, some of which are glycosylated. While about 10% of the capsule is composed of proteins, there is very little lipid present (31, 37). No evidence for the presence of lipoarabinomannan in the capsule was found, though phosphatidylinositol mannoside (PIM) was identified (38). The presence of a glycan-rich capsule surrounding intracellular mycobacteria has been confirmed using specific monoclonal antibodies (MAbs) against arabinomannan and glucan (58, 59).We have shown previously that mechanical removal of capsular material from M. tuberculosis results in a 10-fold increase in bacterial binding to Mφ, suggesting that the capsule can act as an antiphagocytic barrier that limits the interaction of M. tuberculosis with Mφ (65). However, even though the capsule reduces binding of M. tuberculosis to Mφ, it does not eliminate it, and it is clear that at least some bacteria maintain the capacity to bind to Mφ. These observations, along with our earlier studies showing that only certain populations of Mφ efficiently bind M. tuberculosis (64, 67), suggest that the M. tuberculosis capsule modulates the interaction of bacteria with host cells, preventing uptake by some populations of Mφ and directing the bacteria to specific Mφ types or particular receptor-ligand interactions. In this study, we have evaluated the diversity of proteins present in the M. tuberculosis capsule and assessed the role of two bacterial molecular chaperones, Cpn60.2 and DnaK, in host cell binding. Using both competitive-inhibition and epitope-masking strategies, we have shown that while both Cpn60.2 and DnaK are present on the bacterial surface, only Cpn60.2 appears to be necessary to facilitate efficient bacterial association with Mφ.     

GIS-based analysis of the fate of waste-related pathogens Cryptosporidium parvum, Giardia lamblia and Escherichia coli in a tropical canal network

Urban canals play a major socio-economic role in many tropical countries and, particularly, Thailand. One of the overlooked functions that they perform is a significant attenuation of waste-related pathogens posing considerable health risk, as well as pollution attenuation in general. The study dealt with a comparison of three canals receiving: (i) municipal, (ii) mainly industrial and (iii) mainly agricultural wastewater, listed in order of progressively decreasing organic loading. The occurrence and fate of waterborne Cryptosporidium parvum, Giardia lamblia and Escherichia coli were monitored in the canals by both real-time PCR and conventionally for 12 months. The pathogens are etiological agents of an estimated 38% and 47% of diarrhea cases worldwide and in Thailand, respectively. The geographic information system (GIS) was used to evaluate and map point and, particularly, non-point pollution sources which allowed differentiating the canal sections in terms of predominant pathogen sources. The flowthrough canals, which can be viewed as waste stabilization ponds, were found to be efficiently removing the pathogens at the following generalized specific rates: 0.3 (C. parvum), 1.2 (G. lamblia), 1.8 (E. coli) log10/km.d in the dry season. The rates decreased in the rainy season for E. coli and G. lamblia, but increased for C. parvum which indicated different removal mechanisms. Data suggest that E. coli and G. lamblia were mainly removed through sedimentation and sunlight (UV) irradiation, while the likely mechanism for C. parvum was predation. Overall, the specific pathogen removal rates positively correlated with the canal organic loading rates in the rainy season. As an important result, an estimate of the municipal pollution mitigation by over 2280 km canals in the Greater Bangkok suggests that concomitant to the pathogens at least 36-95 tons of BOD5 is being removed daily, thereby saving the receiving Chao Phraya River and Bight of Bangkok, by far exceeding current, from major eutrophication problems.     

Ability of mothers to diagnose fever and anaemia in their young children, in a malaria-endemic region of West Africa

The rapid and correct diagnosis of fever and anaemia at the household level is a prerequisite for the successful management and control of life-threatening disease among young children, particularly in malaria-endemic areas of Africa. The ability of mothers to diagnose fever and anaemia in their young children has recently been explored, as part of a large, birth-cohort study in rural, north-western Burkina Faso. During a cross-sectional survey in six villages, 345 children aged, <3 years and their mothers were investigated. Each mother was asked if she considered her child to be febrile and/or anaemic before that child's temperature and haematocrit were measured, with an electronic thermometer and portable centrifuge, respectively. The recorded prevalences of fever (> or =37.5 degrees C) and anaemia (haematocrit, <25%) in the children were 12.2% and 21.4%, respectively. The mothers' diagnoses had a sensitivity of 76.2% [95% confidence interval (CI)=60.6%-88.0%] for fever and 4.1% (CI=0.8%-11.4%) for anaemia, with corresponding specificities of 87.1% (CI=82.8%-90.7%) and 95.9% (CI=92.9%-98.0%). Mothers in rural Africa appear to be fairly accurate in detecting fever in their children but less accurate in detecting anaemia. While malaria control needs to employ a mix of preventive and curative measures, anaemia control will benefit from community-based malaria-control measures as well as broader approaches addressing the nutritional status of young children.     

Ethnobotanical survey and antibacterial activity of some plants used in Guinean traditional medicine

A total of 418 healers have been interviewed in Guinea, a coastal country of West Africa, ranging between 7 degrees 30 and 12 degrees 30 of northern latitude and 8 degrees and 15 degrees of western longitude. Plant species used by the local inhabitants to treat infectious diseases were identified using ethnobotanical, ethnographic and taxonomic methods. During these investigations, 218 plants were registered, of which the following were the most frequently used: Erythrina senegalensis, Bridelia ferruginea, Crossopteryx febrifuga, Ximenia americana, Annona senegalensis, Cochlospermum tinctorium, Cochlospermum planchonii, Lantana camara, Costus afer, Psidium guajava, Terminalia glaucescens, Uapaca somon and Swartzia madagascariensis. Most plants, and especially the leaves, were essentially used as a decoction. In order to assess antibacterial activity, 190 recipes were prepared and biologically tested, among which six showed activity (minimal inhibitory concentration<125 microg/ml) against Bacillus cereus, Mycobacterium fortuitum, Staphylococcus aureus, or Candida albicans, i.e., Entada africana, Chlorophora regia, Erythrina senegalensis, Harrisonia abyssinica, Uvaria tomentosa, and a mixture of six plants consisting of Swartzia madagascariensis, Isoberlinia doka, Annona senegalensis, Gardenia ternifolia, Terminalia glaucescens and Erythrina senegalensis.     

Comparaison de l’efficacité thérapeutique et de la tolérance du praziquantel administré en prise unique à la dose de 40 versus 60 mg/kg pour le traitement de la bilharziose urinaire en Mauritanie

During the last twenty years, praziquantel (PZQ) was the drug of choice for the treatment of schistosomiasis in the majority of national programs. However, a lower rate of cure had been significantly noted on the left bank of the Senegal River. To explain this unusual rate of cure, the assumption of a possible resistance to the drug as well as under-dosing was considered. With an aim of testing this hypothesis of underdosing, we compared the amount of a single dose of 60 mg/kg of PZQ versus the standardized dose of 40 mg/kg used in curing urinary schistosomiasis in Mauritania. One hundred and fifty-one children aged from 10 to 19 years, including 77 in the group of 60 mg/kg and 74 in the group of 40 mg/ kg, were included in the study. The rates of cure were respectively 64.8% for 60 mg/kg and 67.5% for 40 mg/kg three weeks after the administration of the treatment without statistically significant difference. For the majority of the patients, the drug was well tolerated and no serious adverse events were noted; however, clinical signs in the form of abdominal pain associated or not with diarrhea and vomiting were noted. Praziquantel remains an effective and well-tolerated drug: the amount of 40 mg/kg of body weight can still be maintained for the treatment of schistosomiasis in Mauritania.     

Population genetics of Trypanosoma brucei gambiense,the agent of sleeping sickness in Western Africa

Human African trypanosomiasis, or sleeping sickness caused by Trypanosoma brucei gambiense, occurs in Western and Central Africa. T. brucei s.l. displays a huge diversity of adaptations and host specificities, and questions about its reproductive mode, dispersal abilities, and effective size remain under debate. We have investigated genetic variation at 8 microsatellite loci of T. b. gambiense strains isolated from human African trypanosomiasis patients in the Ivory Coast and Guinea, with the aim of knowing how genetic information was partitioned within and between individuals in both temporal and spatial scales. The results indicate that (i) migration of T. b. gambiense group 1 strains does not occur at the scale of West Africa, and that even at a finer scale (e.g., within Guinea) migration is restricted; (ii) effective population sizes of trypanosomes, as reflected by infected hosts, are probably higher than what the epidemiological surveys suggest; and (iii) T. b. gambiense group 1 is most likely a strictly clonally reproducing organism.     

Cervical Cancer in Sub-Saharan Africa: A Multinational Population-Based Cohort Study of Care and Guideline Adherence

BackgroundCervical cancer (CC) is the most common female cancer in many countries of sub‐Saharan Africa (SSA). We assessed treatment guideline adherence and its association with overall survival (OS).MethodsOur observational study covered nine population‐based cancer registries in eight countries: Benin, Ethiopia, Ivory Coast, Kenya, Mali, Mozambique, Uganda, and Zimbabwe. Random samples of 44–125 patients diagnosed from 2010 to 2016 were selected in each. Cancer‐directed therapy (CDT) was evaluated for degree of adherence to National Comprehensive Cancer Network (U.S.) Guidelines.ResultsOf 632 patients, 15.8% received CDT with curative potential: 5.2% guideline‐adherent, 2.4% with minor deviations, and 8.2% with major deviations. CDT was not documented or was without curative potential in 22%; 15.7% were diagnosed with International Federation of Gynecology and Obstetrics (FIGO) stage IV disease. Adherence was not assessed in 46.9% (no stage or follow‐up documented, 11.9%, or records not traced, 35.1%). The largest share of guideline‐adherent CDT was observed in Nairobi (49%) and the smallest in Maputo (4%). In patients with FIGO stage I–III disease (n = 190), minor and major guideline deviations were associated with impaired OS (hazard rate ratio [HRR], 1.73; 95% confidence interval [CI], 0.36–8.37; HRR, 1.97; CI, 0.59–6.56, respectively). CDT without curative potential (HRR, 3.88; CI, 1.19–12.71) and no CDT (HRR, 9.43; CI, 3.03–29.33) showed substantially worse survival.ConclusionWe found that only one in six patients with cervical cancer in SSA received CDT with curative potential. At least one‐fifth and possibly up to two‐thirds of women never accessed CDT, despite curable disease, resulting in impaired OS. Investments into more radiotherapy, chemotherapy, and surgical training could change the fatal outcomes of many patients.Implications for PracticeDespite evidence‐based interventions including guideline‐adherent treatment for cervical cancer (CC), there is huge disparity in survival across the globe. This comprehensive multinational population‐based registry study aimed to assess the status quo of presentation, treatment guideline adherence, and survival in eight countries. Patients across sub‐Saharan Africa present in late stages, and treatment guideline adherence is remarkably low. Both factors were associated with unfavorable survival. This report warns about the inability of most women with cervical cancer in sub‐Saharan Africa to access timely and high‐quality diagnostic and treatment services, serving as guidance to institutions and policy makers. With regard to clinical practice, there might be cancer‐directed treatment options that, although not fully guideline adherent, have relevant survival benefit. Others should perhaps not be chosen even under resource‐constrained circumstances.     

The epidemiology of Neisseria meningitidis meningitis in Togo during 2003-2005

Few reports documenting the epidemiology of Neisseria meningitidis (Nm) serogroup W135 exist, and none from Togo. During 2003-2005, we conducted acute bacterial meningitis surveillance at three major reference hospitals in Togo. Of 116 Nm identified, 83 (71%) were NmA, 23 (20%) were NmW135, and 10 (9%) did not have a serogroup identified. Nine percent of NmW135 cases and 35% of NmA cases occurred among those aged 15 years or older. The two hospitals in central Togo reported 23% of all Nm cases and 78% of NmW135 cases. Twelve of the 23 NmW135 cases occurred during February-March 2003, while the remaining 11 occurred sporadically over the remaining 18 months of the study. NmW135 meningitis showed pronounced temporal and geographic clustering and occurred almost exclusively among those younger than 15 years old. By the 2004-2005 epidemic season, NmW135 had largely disappeared from Togo for unknown reasons.