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Multicentre laboratory validation of the colorimetric redox indicator (CRI) assay for the rapid detection of extensively drug-resistant (XDR) Mycobacterium tuberculosis
No full textObjectives To perform a multicentre study to evaluate the performance of the colorimetric redox indicator (CRI) assay and to establish the MICs and critical concentrations of rifampicin, isoniazid, ofloxacin, kanamycin and capreomycin. Methods The study was carried out in two phases. Phase I determined the MIC of each drug. Phase II established critical concentrations for the five drugs tested by the CRI assay compared with the conventional proportion method. Results Phase I: a strain was considered resistant by the CRI assay if the MIC was >/=0.5 mg/L for rifampicin, >/=0.25 mg/L for isoniazid, >/=4.0 mg/L for ofloxacin and >/=5.0 mg/L for kanamycin and capreomycin. Sensitivity was 99.1% for isoniazid and 100% for the other drugs and specificity was 97.9% for capreomycin and 100% for the other drugs. Phase II: the critical concentration was 0.5 mg/L for rifampicin, 0.25 mg/L for isoniazid, 2.0 mg/L for ofloxacin and 2.5 mg/L for kanamycin and capreomycin giving an overall accuracy of 98.4%, 96.6%, 96.7%, 98.3% and 90%, respectively. Conclusions Results demonstrate that the CRI assay is an accurate method for the rapid detection of XDR Mycobacterium tuberculosis. The CRI assay is faster than the conventional drug susceptibility testing method using solid medium, has the same turnaround time as the BACTEC MGIT 960 system, but is less expensive, and could be an adequate method for low-income countries
Clonal differences between Non-Typhoidal Salmonella (NTS) recovered from children and animals living in close contact in The Gambia
No full textBACKGROUND: Non-Typhoidal Salmonella (NTS) is an important cause of invasive bacterial disease and associated with mortality in Africa. However, little is known about the environmental reservoirs and predominant modes of transmission. Our study aimed to study the role of domestic animals in the transmission of NTS to humans in rural area of The Gambia. METHODOLOGY: Human NTS isolates were obtained through an active population-based case-control surveillance study designated to determine the aetiology and epidemiology of enteric infections covering 27,567 Gambian children less than five years of age in the surveillance area. Fourteen children infected with NTS were traced back to their family compounds and anal swabs collected from 210 domestic animals present in their households. Identified NTSs were serotyped and genotyped by multi-locus sequencing typing. PRINCIPAL FINDINGS: NTS was identified from 21/210 animal sources in the households of the 14 infected children. Chickens carried NTS more frequently than sheep and goats; 66.6%, 28.6% and 4.8% respectively. The most common NTS serovars were S. Colindale in humans (21.42%) and S. Poona in animals (14.28%). MLST on the 35 NTS revealed four new alleles and 24 sequence types (ST) of which 18 (75%) STs were novel. There was no overlap in serovars or genotypes of NTS recovered from humans or animal sources in the same household. CONCLUSION: Our results do not support the hypothesis that humans and animals in close contact in the same household carry genotypically similar Salmonella serovars. These findings form an important baseline for future studies of transmission of NTS in humans and animals in Africa
Genotypic impact of prolonged detectable HIV-1 RNA viral load after HAART failure in a CRF01_AE infected cohort
No full textHIV-subtype specific data on mutation type, rate and accumulation following HAART treatment failure are limited. We studied patterns and accrual of drug resistance mutations in a Cambodian CRF01_AE-infected cohort continuing a virologically failing first-line, nonnucleoside reverse transcriptase inhibitor- (NNRTI-) based, HAART. Between 2005 and 2007, 837 adult HIV-infected patients had regular plasma HIV-1 RNA viral load measurements at Sihanouk Hospital Centre of Hope (SHCH), Cambodia. Drug resistance testing was performed in all patients with HIV-1 RNA >1000 copies/mL, after at least 6 months of HAART. Seventy-one patients with a mean age of 34 years, of whom 68% were male, were retrospectively assessed at virological failure. The median duration of antiretroviral therapy was 12.3 (IQR 7.1-18.23) months, the median CD4 cell count was 173 (IQR 118-256) cells/mm(3), and the mean plasma HIV-1 RNA viral load was 3.9 log (SD 0.72) at failure. NNRTI mutations, M184I/V mutation, thymidine analogue mutations and K65R were observed in 78.9%, 69%, 20%, and 12.7% of patients respectively. For 33 patients, genotypic testing was carried out on at least two occasions before the switch to second-line HAART after a median duration of 5.8 (IQR 4.3-6.1) months of virological failure: 54.5% of patients accumulated new mutations with a rate of 1.6 mutations per person-year. Accumulation was seen both for nucleoside and nonnucleoside reverse transcriptase inhibitors, and also in patients with low-level viremia. Subtype-specific data on mutation type, rate, and accumulation after HAART failure are urgently needed to optimize treatment strategies in resource-limited settings
Incidence and predictors of mortality and the effect of tuberculosis immune reconstitution inflammatory syndrome in a cohort of TB/HIV patients commencing antiretroviral therapy
No full textBACKGROUND:: Tuberculosis-HIV (TB-HIV) co-infection remains an important cause of mortality in antiretroviral therapy (ART) programmes. In a cohort of TB-HIV co-infected patients starting ART we examined the incidence and predictors of early mortality. METHODS:: Consecutive TB-HIV co-infected patients eligible for ART were enrolled in a cohort study at the Mulago National Tuberculosis and Leprosy Programme clinic in Kampala, Uganda. Predictors of mortality were assessed using Cox proportional hazards analysis. RESULTS:: Three hundred and two patients (median CD4 count 53 cells/muL (interquartile range, 20-134)) were enrolled. Fifty three patients died, 36 (68%) of these died within the first 6 months of TB diagnosis. Male sex (HR, 2.19; 95% CI, 1.19-4.03; p=0.011), anergy to tuberculin skin test (HR 2.59 (1.10-6.12); p=0.030), a positive serum cryptococcal antigen (serum CrAG) result at enrollment (HR, 4.27; 95% CI, 1.50-12.13; p=0.006) and no ART use (HR, 4.63; 95% CI, 2. 37-9.03; p=<0.001) were independent predictors of mortality by multivariate analysis. Six (10%) patients with TB-immune reconstitution inflammatory syndrome died and in most an alternative contributing cause of death was identified. CONCLUSION:: Mortality among these TB-HIV co-infected patients was high particularly when presenting with advanced HIV disease and not starting ART, reinforcing the need for timely and joint treatment for both infections. Screening for a concomitant cryptococcal infection and antifungal treatment for patients with cryptococcal antigenemia may further improve clinical outcome
Factors associated with eating out of home in Vietnamese adolescents
No full textEating out of home (OH) is nutritionally important in some developing countries. This study identifies the factors associated with eating OH in Vietnamese adolescents. Data were obtained from a cross-sectional cluster survey of 502 adolescents in rural and urban areas in Vietnam. Factors associated with eating OH were recorded with a Likert scale and analysed using factor analysis. Data on eating OH was collected using a frequency questionnaire and a 1-day 24h recall. A first pattern "Convenience" incorporated preparation time, price, variety, taste, proximity and social aspects as items associated with eating OH. A second pattern "Nutritional and food safety concerned" reflects concerns with regard to hygiene, fat and salt content of the food prepared OH. Adolescents characterised by the convenience pattern were more likely (OR=1.51, P<0.001) to eat OH more frequently. The highest tertile of the Nutritional and food safety concerned pattern was less likely (OR=0.61, P=0.03) to eat OH compared to lower tertiles. Both patterns were not associated with the % energy from eating OH per day. Convenience and to a lesser extent Nutritional and food safety concerns are significant factors associated with the frequency of eating OH in Vietnamese adolescents
Sensitive detection of nucleic acids by PNA hybridization directed co-localization of fluorescent beads
No full textWe have designed a pair of biotinylated peptide nucleic acid (PNA) probes targeting two sequences in 18S rRNA (from the parasite Trypanosoma brucei) at a distance of 191 nt (corresponding to maximum distance of ca. 60 nm) from each other. The PNA probes were individually bound to (strept)avidin-coated fluorescent beads, differing in size and color [green beads (1 microm) and red beads (5.9 microm)], thereby allowing distinct detection of each PNA probe by conventional fluorescence microscopy. These two PNA beads showed easily detectable co-localization when simultaneously hybridizing to a target nucleic acid. The assay detected the parasite 18S rRNA down to 1.6 fmol while there was no such co-localization visible with human 18S rRNA not containing the PNA targets. Furthermore, the assay showed positive detection with 1.6 ng of total RNA (corresponding to RNA from ca. 300 parasites). Upon further optimization this method may provide a new tool for a diagnosis of Human African Trypanosomiasis (HAT) and it may more generally have applications within diagnostics for (neglected) infectious diseases
Incidence of symptomatic and asymptomatic Leishmania donovani infections in high-endemic foci in India and Nepal: a prospective study
No full textIncidence of Leishmania donovani infection and Visceral Leishmaniasis (VL) was assessed in a prospective study in Indian and Nepalese high-endemic villages. DAT-seroconversion was used as marker of incident infection in 3 yearly surveys. The study population was followed up to month 30 to identify incident clinical cases. In a cohort of 9034 DAT-negative individuals with neither active signs nor history of VL at baseline, 42 VL cases and 375 asymptomatic seroconversions were recorded in the first year, giving an infectionratiodisease ratio of 8.9 to 1. In the 18 months' follow-up, 7 extra cases of VL were observed in the seroconverters group (N = 375), against 14 VL cases among the individuals who had not seroconverted in the first year (N = 8570) (RR = 11.5(4.5<RR<28.3)). Incident asymptomatic L. donovani infection in VL high-endemic foci in India and Nepal is nine times more frequent than incident VL disease. About 1 in 50 of these new but latent infections led to VL within the next 18 months
Prospective multicenter evaluation of the expert system "KABISA TRAVEL" in diagnosing febrile illnesses occurring after a stay in the tropics
No full textBackground. KABISA TRAVEL is a clinical decision support system developed by the Institute of Tropical Medicine of Antwerp, Belgium, for the diagnosis of febrile illnesses after a stay in the tropics. This study aimed to compare the diagnostic accuracy of KABISA TRAVEL with that of expert travel physicians. Methods. From December 2007 to April 2009, travelers with fever after a stay in the tropics were included in a multicenter trial conducted in travel referral centers in the Netherlands, Italy, Spain, and Belgium. Physicians were asked (1) to rank their first assessment diagnoses, (2) to enter in KABISA TRAVEL clinical and laboratory data available within 36 hours, and (3) to interact with the tutor until its final diagnostic ranking. Both physicians and KABISA TRAVEL rankings were then compared with the final diagnosis confirmed by reference methods. The clinical utility was also surveyed. Results. A total of 205 cases with confirmed diagnosis were evaluated (male/female ratio: 1.85; mean age: 35 y). Most patients were western travelers or expatriates (60%) and were returning from sub-Saharan Africa (58%). Travel physicians and KABISA TRAVEL ranked the correct diagnosis in the first place for 70 and 72% of the cases, respectively, and within the top five both for 88% of them. Travel physicians reported having been suggested useful further investigations in 16% of the cases, and having been helped for obtaining the diagnosis in 24%. This was reported more frequently when they had initially missed the diagnosis (suggestion: 48% in missed vs 12% in found diagnoses, p < 0.001; helpful: 48% in missed vs 21% in found diagnoses, p = 0.005). Conclusions. KABISA TRAVEL performed as well as expert travel physicians in diagnosing febrile illnesses occurring after a tropical stay. Clinicians perceived the system as more helpful when they had not immediately considered the correct diagnosis
Natural Leishmania donovani/Leishmania aethiopica hybrids identified from Ethiopia
No full textNatural hybridization events have been demonstrated between closely and distantly related Leishmania groups despite a predominantly clonal and endogamically sexual mode of reproduction. Here we report the first natural hybrid between Leishmania aethiopica and Leishmania donovani, as evidenced from the analysis of several clones from strain MHOM/ET/94/ABAUY. Targeted species-identification PCRs revealed the presence of both genotypes, and amplified fragment length polymorphisms indicated that the clones are genetically in an intermediate position between both parental species, being more closely related to L. aethiopica. The possible scenario facilitating hybrid formation is not clear, but is discussed in relation to epidemiological data