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Novel hypertonic saline-sodium hydroxide (HS-SH) method for decontamination and concentration of sputum samples for Mycobacterium tuberculosis microscopy and culture
No full textThis study evaluated a new decontamination and concentration (DC) method for sputum microscopy and culture. Sputum samples from patients with suspected pulmonary tuberculosis (TB) (n=106) were tested using the proposed hypertonic saline–sodium hydroxide (HS–SH) DC method, the recommended N-acetyl-L-cysteine–sodium citrate–sodium hydroxide (NALC-NaOH) DC method and unconcentrated direct smear (Ziehl–Neelsen) techniques for the presence of mycobacteria using Löwenstein-Jensen culture and light microscopy. Of 94 valid specimens, 21 (22.3 %) were positive in culture and were further characterized as Mycobacterium tuberculosis. The sensitivity for acid-fast bacilli (AFB) smears was increased from 28.6 % using the direct method to 71.4 % (HS–SH) and 66.7 % (NALC-NaOH) using DC methods. Both concentration techniques were highly comparable for culture (kappa=0.794) and smear (kappa=0.631) for AFB. Thus the proposed HS–SH DC method improved the sensitivity of AFB microscopy compared with a routine unconcentrated direct smear; its performance was comparable to that of the NALC-NaOH DC method for AFB smears and culture, but it was methodologically simpler and less expensive, making it a promising candidate for evaluation by national TB control programmes in developing countries
Roel Coutinho: Director of the Centre for Infectious Disease Control Netherlands [interview]
No full textIn 2005, Roel Coutinho became the first director of the Netherlands' new national coordination centre for infectious diseases. After graduating in medicine in 1972 from Amsterdam University, and a sojourn as a physician in tropical medicine in Senegal and Guinea-Bissau, Coutinho returned to the Netherlands to specialise as a medical microbiologist. Coutinho joined the Municipal Health Service of Amsterdam in 1977 as the head of the Public Health Department, where in 1984 he completed a PhD on sexually transmitted diseases among men who have sex with men. He was one of the founders of the Amsterdam cohort studies. In 1989, Coutinho was appointed Professor in the Epidemiology and Prevention of Infectious Diseases at the Academic Medical Center, University of Amsterdam. In 2000 he became General Director of the Municipal Health Service of Amsterdam, a post he occupied until joining the RIVM (National Institute for Public Health and the Environment) in 2005. Roel Coutinho has contributed to more than 450 international publications. Since 2000 he has been a coeditor of the international scientific journal AIDS. He has two children and two grandchildren
Performance and acceptability of the FluoLED Easy (TM) module for tuberculosis fluorescence microscopy
No full textSETTING: Tuberculosis (TB) reference laboratory in Bangkok, Thailand, and two health centres in Dar es Salaam, Tanzania. OBJECTIVES: To assess the performance and user-friendliness of a light-emitting diode (LED) module (FluoLED Easy) for TB fluorescence microscopy (FM). DESIGN: Equivalence study vs. conventional FM in Bangkok using blinded re-reading; routine detection in the health centres in Dar es Salaam compared to Ziehl-Neelsen (ZN) over 2 years, with rechecking of FM smears. RESULTS: For 461 smears re-read, 99.1% concordance with conventional FM was obtained. FluoLED introduction caused a lasting increase in detection in the routine of each of the health centres by on average 20%. Blinded rechecking failed due to unreliable registration. Onsite rechecking of a convenience sample showed absence of false-positive results in one centre and confusion with artefacts that could have been avoided by more training in the other. LED FM was highly appreciated, with both laboratories refusing to revert to ZN as originally intended. CONCLUSIONS: A simple microscope with a FluoLED module can yield results equivalent to those of conventional FM. Low cost, technical appropriateness and excellent acceptance justify its use in low-income settings, contrary to classical systems. LED FM can lead to increased sensitivity, but for optimal yield good training and quality assurance remain essential requirements
Population-level effect of HSV-2 therapy on the incidence of HIV in sub-Saharan Africa
No full textBackground: Herpes simplex virus type 2 (HSV-2)
infection increases acquisition and transmission of HIV,
but the results of trials measuring the impact of HSV-2
therapy on HIV genital shedding and HIV acquisition are
mixed, and the potential impact of HSV-2 therapy on the
incidence of HIV at the population level is unknown.
Methods: The effects of episodic and suppressive HSV-2
therapy were simulated using the individual-level model
STDSIM fitted to data from Cotonou, Benin (relatively low
HIV prevalence) and Kisumu, Kenya (high HIV prevalence).
Clinician- and patient-initiated episodic therapy, started
when symptomatic, were assumed to reduce ulcer
duration. Suppressive therapy, given regardless of
symptoms, was also assumed to reduce ulcer frequency
and HSV-2 infectiousness.
Results: Clinician-initiated episodic therapy in the general
population had almost no effect on the incidence of HIV.
The impact of patient-initiated therapy was higher
because of earlier treatment initiation, but still low (,5%)
unless symptom recognition and treatment-seeking
behaviour were very high. Suppressive therapy given to
female sex workers (FSW) in Kisumu had little effect on
population HIV incidence. In Cotonou, suppressive therapy
in FSW with high coverage and long duration reduced
population HIV incidence by .20% in the long term.
Impact was increased in both cities by also treating a
proportion of their clients. Long-term suppressive therapy
with high coverage in the general population could reduce
HIV incidence by more than 30%.
Conclusions: These results show that HSV-2 therapy
could potentially have a population-level impact on the
incidence of HIV, especially in more concentrated
epidemics. However, a substantial impact requires high
coverage and long duration therapy, or very high symptom
recognition and treatment-seeking behaviour
Bayesian clinical reasoning: does intuitive estimation of likelihood ratios on an ordinal scale outperform estimation of sensitivities and specificities?
No full textRationale: Bedside use of Bayes' theorem for estimating probabilities of diseases is cumbersome. An alternative approach based on five categories of powers of tests from 'useless' to 'very strong' has been proposed. The performance of clinicians using it was assessed.
Methods Fifty clinicians attending a course of tropical medicine estimated powers of tests and post-test probabilities using the classical vs. the categorical Bayesian approach. The estimation of post-test probability was assessed for real and dummy diseases in order to avoid the bias of previous knowledge. Accuracy of answers was measured by the difference with reference values obtained from an expert system (Kabisa).
Results Clinicians estimated positive likelihood ratios (LRs) a median of −1.07 log10 lower than Kabisa [interquartile range (IQR): −1.47; −0.80] when derived classically and −0.17 (IQR: −0.42; +0.04) when estimated categorically (P < 0.001). For negative LRs the median was +0.39 log10 higher (IQR: +0.71; +0.08) when derived classically and −0.18 log10 lower (IQR: +0.03; −0.36) when estimated categorically (P < 0.001).
Twenty (40%) disclosed not being able to calculate post-test probabilities using sensitivities and specificities. Regardless the approach post-test probabilities were overestimated both for real and dummy diseases [respectively +1.23 log10 (IQR: +0,67; +2.08) and +2.03 log10 (IQR: +0.49; +2.42)] (P = 0277), but the range was wider for the latter (P = 0.001).
Conclusions Participants were more accurate in estimating powers with a categorical approach than with sensitivities and specificities. Post-test probabilities were overestimated with both approaches. Knowledge of the disease did not influence the estimation of post-test probabilities. A categorical approach might be an interesting instructional tool, but the effect of training with this approach needs assessment
In vitro anti-microbial activity of the Cuban medicinal plants Simarouba glauca DC, Melaleuca leucadendron L and Artemisia absinthium L
No full textIn the present study, an extensive in vitro antimicrobial profiling was performed for three medicinal plants grown in Cuba, namely Simarouba glauca, Melaleuca leucadendron and Artemisia absinthium. Ethanol extracts were tested for their antiprotozoal potential against Trypanosoma b. brucei, Trypanosoma cruzi, Leishmania infantum and Plasmodium falciparum. Antifungal activities were evaluated against Microsporum canis and Candida albicans whereas Escherichia coli and Staphylococcus aureus were used as test organisms for antibacterial activity. Cytotoxicity was assessed against human MRC-5 cells. Only M. leucadendron extract showed selective activity against microorganisms tested. Although S. glauca exhibited strong activity against all protozoa, it must be considered non-specific. The value of integrated evaluation of extracts with particular reference to selectivity is discussed
Processing practices contributing to Campylobacter contamination in Belgian chicken meat preparations
No full textThe aim of this study was to obtain insight into processing practices in the poultry sector contributing to the variability in Campylobacter contamination in Belgian chicken meat preparations. This was achieved by company profiling of eleven food business operators, in order to evaluate variation of processing management, in addition to statistical modelling of microbiological testing results for Campylobacter spp. contamination in 656 end product samples. Almost half (48%) of chicken meat preparation samples were positive for Campylobacter spp. Results revealed a statistically significant variation in Campylobacter contamination between 11 chicken meat producers across Belgium at both quantitative and qualitative detection levels. All producers provided Campylobacter-positive samples, but prevalence ranged from 9% up to 85% at single producer level. The presence or addition of skin during production of chicken meat preparations resulted in almost 2.2-fold increase in the probability of a sample being positive for Campylobacter, while chicken meat preparations made from frozen meat, or partly containing pre-frozen meat, had a significant (Odds Ratio=0.41; CI 95% 0.18:0.98) lower probability of being positive for Campylobacter. However, the quantitative results indicated that the positive freezing effect on Campylobacter count was compromised by the presence and/or adding of skin
Prevention of blood-borne diseases in Bolivia, 1993-2002
No full textThis report shows the outcome of a coordinated effort by locals, foreign institutions, and an international agency, from 1996-2002, aimed at preventing transmission of blood-borne diseases in Santa Cruz, Bolivia. From 2001-2002, testing the donor pool for HIV prevented transfusion of 32 infected units and 29 infections. With 100% screening coverage, 196 hepatitis B virus (HBV)-infected units were discarded, and 177 infections of HBV were prevented between 1999 and 2002. Incomplete screening for hepatitis C virus (HCV) may have tainted nine units of blood and generated eight HCV infections in 1999. On the other hand, 600 units infected with HCV were discarded, and 540 HCV infections were prevented between 1999 and 2002. Screening for Chagas disease prevented transfusion of 10,661 tainted units and 2,133 infections from 1999 to 2002. From 1996-2002, the investment was US$1,108,000
