Perceptions of Research Bronchoscopy in Malawian Adults with Pulmonary Tuberculosis: A Cross-Sectional Study

Bronchoscopy is an established research tool in Malawi, enabling collection of pulmonary samples for immunological, pharmacological, and microbiological studies. It is, however, an invasive clinical procedure that offers no direct benefit to volunteering participants when used in a research capacity alone, and thus informed consent is essential. This study aimed to explore TB patients’ understanding of research bronchoscopy, what would motivate them to participate in research bronchoscopy, and their concerns, in order to inform consenting processes for future clinical studies. We used a qualitative research design. Two focus group discussions were conducted with community members and TB patients to understand their perceptions of bronchoscopy. Transcripts were coded by multiple co-authors and thematic content analysis was used to analyse main findings. We found that Malawian patients with pulmonary TB were willing to participate in a study using research bronchoscopy for health assessment and access to improved healthcare. We identified information of value to potential participants when consenting to that may lessen some of the anxieties expressed by participants. Patient and public involvement is essential to improve informed consent and institutional trust

Transduction of linked chromosomal genes between Pseudomonas aeruginosa strains during incubation in situ in a freshwater habitat

Both transduction of single chromosomal loci and cotransduction of closely linked loci were observed between lysogenic and nonlysogenic strains of Pseudomonas aeruginosa in a freshwater habitat. Transductants were recovered at frequencies of 10-6 to 10-5 transductants per CFU. Transductants of lysogenized strains were recovered 10- to 100-fold more frequently than were transductants of nonlysogenic parents. Lysogens are thus capable of introducing phages which mediate generalized transduction into the natural microbial community and serving as recipients of transduced DNA. It would appear that lysogeny has the potential of increasing the size and flexibility of the gene pool available to natural populations of bacteria. The ability to generate and select new genetic combinations through phage-mediated exchange can be significant in the face of a continually changing environment and may contribute to the apparent fitness of the lysogenic state in natural ecosystems.Peer reviewedMicrobiology and Molecular Genetic

Pharmacokinetics of lamivudine and lamivudine-triphosphate after administration of 300 milligrams and 150 milligrams once daily to healthy volunteers: Results of the ENCORE 2 Study

There is interest in evaluating the efficacy of lower doses of certain antiretrovirals for clinical care. We determined here the bio-equivalence of plasma lamivudine (3TC) and intracellular 3TC-triphosphate (3TC-TP) concentrations after the administration of two different doses. ENCORE 2 was a randomized crossover study. Subjects received 3TC at 300 and 150 mg once daily for 10 days (arm 1; n = 13) or vice versa (arm 2; n = 11), separated by a 10-day washout. Pharmacokinetic (PK) profiles (0 to 24 h) were assessed on days 10 and 30. Plasma 3TC and 3TC-TP levels in peripheral blood mononuclear cells were quantified by high-performance liquid chromatography-tandem mass spectrometry. Within-subject changes in PK parameters (the area under the concentration-time curve from 0 to 24 h [AUC0-24], the trough concentration of drug in plasma at 24 h [C24], and the maximum concentration of drug in plasma [Cmax]) were evaluated by determining the geometric mean ratios (GMRs) adjusted for study arm, period, and intra-individual variation. Regimens were considered bioequivalent if the 90% confidence interval (90% CI) fell within the range of 0.8 to 1.25. A total of 24 subjects completed the study. The GM (90% CI) 3TC AUC0-24), expressed as ng•h/ml, for the 300- and 150-mg doses were 8,354 (7,609 to 9,172) and 4,773 (4,408 to 5,169), respectively. Bioequivalence in 3TC PK following the administration of 300 and 150 mg was not demonstrated: the GMRs for AUC0-24, C24, and Cmax were 0.57 (0.55 to 0.60), 0.63 (0.59 to 0.67), and 0.56 (0.53 to 0.60), respectively. The GM (90% CI) 3TC-TP AUC0-24 values (pmol•h/106 cells) for the 300- and 150-mg doses were 59.5 (51.8 to 68.3) and 44.0 (38.0 to 51.0), respectively. Bioequivalence in 3TC-TP PK following the administration of 300 and 150 mg was not demonstrated: the GMRs for AUC0-24, C24, and Cmax were 0.73 (0.64 to 0.83), 0.82 (0.68 to 0.99), and 0.70 (0.61 to 0.82), respectively. We found that 3TC at 150 mg is not bioequivalent to the standard regimen of 300 mg, indicating that saturation of cytosine phosphorylation pathways is not achieved at a dose of 150 mg

Pharmacodynamic modeling of bacillary elimination rates and detection of bacterial lipid bodies in sputum to predict and understand outcomes in treatment of pulmonary tuberculosis

This work was supported by a Wellcome Trust Clinical PhD Fellowship (086757/Z/08/A to D. J. S.), the Malawi Liverpool Wellcome Trust Core grant, and Medical Research Council (grant number G0300403 to M. R. B.).Background. Antibiotic-tolerant bacterial persistence prevents treatment shortening in drug-susceptible tuberculosis, and accumulation of intracellular lipid bodies has been proposed to identify a persister phenotype of Mycobacterium tuberculosis cells. In Malawi, we modeled bacillary elimination rates (BERs) from sputum cultures and calculated the percentage of lipid body-positive acid-fast bacilli (%LB + AFB) on sputum smears. We assessed whether these putative measurements of persistence predict unfavorable outcomes (treatment failure/relapse). Methods. Adults with pulmonary tuberculosis received standard 6-month therapy. Sputum samples were collected during the first 8 weeks for serial sputum colony counting (SSCC) on agar and time-to positivity (TTP) measurement in mycobacterial growth indicator tubes. BERs were extracted from nonlinear and linear mixed-effects models, respectively, fitted to these datasets. The %LB + AFB counts were assessed by fluorescence microscopy. Patients were followed until 1 year posttreatment. Individual BERs and %LB + AFB counts were related to final outcomes. Results. One hundred and thirty-three patients (56% HIV coinfected) participated, and 15 unfavorable outcomes were reported. These were inversely associated with faster sterilization phase bacillary elimination from the SSCC model (odds ratio [OR], 0.39; 95% confidence interval [CI], .22-.70) and a faster BER from the TTP model (OR, 0.71; 95% CI, .55-.94). Higher %LB + AFB counts on day 21-28 were recorded in patients who suffered unfavorable final outcomes compared with those who achieved stable cure (P = .008). Conclusions. Modeling BERs predicts final outcome, and high %LB + AFB counts 3-4 weeks into therapy may identify a persister bacterial phenotype. These methods deserve further evaluation as surrogate endpoints for clinical trials.Publisher PDFPeer reviewe

Genetic determinants of the pharmacokinetic variability of rifampin in Malawian adults with pulmonary tuberculosis

D.J.S. was supported by a Wellcome Trust Clinical PhD Fellowship (086757/Z/08/A to D.J.S.). A.D.M. was supported by a National Institute for Health Research Integrated Clinical Academic Training Fellowship and a Wellcome Trust Clinical PhD Fellowship (105/392/B/14/Z). The Malawi Liverpool Wellcome Trust Clinical Research Programme is supported by a strategic award from the Wellcome Trust.Variable exposure to antituberculosis (TB) drugs, partially driven by genetic factors, may be associated with poor clinical outcomes. Previous studies have suggested an influence of the SLCO1B1 locus on the plasma area under the concentration-time curve (AUC) of rifampin. We evaluated the contribution of single nucleotide polymorphisms (SNPs) in SLCO1B1 and other candidate genes (AADAC and CES-1) to interindividual pharmacokinetic variability in Malawi. A total of 174 adults with pulmonary TB underwent sampling of plasma rifampin concentrations at 2 and 6 h postdose. Data from a prior cohort of 47 intensively sampled, similar patients from the same setting were available to support population pharmacokinetic model development in NONMEM v7.2, using a two-stage strategy to improve information during the absorption phase. In contrast to recent studies in South Africa and Uganda, SNPs in SLCO1B1 did not explain variability in AUC0-∞ of rifampin. No pharmacokinetic associations were identified with AADAC or CES-1 SNPs, which were rare in the Malawian population. Pharmacogenetic determinants of rifampin exposure may vary between African populations. SLCO1B1 and other novel candidate genes, as well as nongenetic sources of interindividual variability, should be further explored in geographically diverse, adequately powered cohorts.Publisher PDFPeer reviewe

Cellulite nécrosante descendante infectieuse d’origine dentaire à diffusion mammaire : Analyse de deux cas

Les cellulites nécrosantes descendantes d’origine dentaire sont graves et de prise en charge difficile. Leur diffusion se fait classiquement vers le médiastin, les cavités pleurales, voir le cerveau. La diffusion spécifique à la glande mammaire est atypique, rare et peu décrite. Nous rapportons 2 cas colligés en 15 ans de pratique de chirurgie thoracique. Il s’agissait de deux patientes, l’une âgée de 32 ans et l’autre de 25 ans toutes vivaient en milieu rural. Leurs itinéraires diagnostiques et thérapeutiques, les facteurs de risque, les moyens thérapeutiques utilisés et leurs pronostics ont été discutés. Le but de ce travail était de mettre l’accent sur la gravité de cette pathologie et inciter à la mise en œuvre d’une politique de prévention à l’échelle nationale

Intrapulmonary Pharmacokinetics of First-line Anti-tuberculosis Drugs in Malawian Patients With Tuberculosis

BACKGROUND: Further work is required to understand the intrapulmonary pharmacokinetics of first-line anti-tuberculosis drugs. This study aimed to describe the plasma and intrapulmonary pharmacokinetics of rifampicin, isoniazid, pyrazinamide, and ethambutol, and explore relationships with clinical treatment outcomes in patients with pulmonary tuberculosis. METHODS: Malawian adults with a first presentation of microbiologically-confirmed pulmonary tuberculosis received standard 6-month first-line therapy. Plasma and intrapulmonary samples were collected 8 and 16 weeks into treatment and drug concentrations measured in plasma, lung/airway epithelial lining fluid, and alveolar cells. Population pharmacokinetic modelling generated estimates of drug exposure (Cmax and AUC) from individual-level post-hoc Bayesian estimates of plasma and intrapulmonary pharmacokinetics. RESULTS: One-hundred-and-fifty-seven patients (58% HIV co-infected) participated. Despite standard weight-based dosing, peak plasma concentrations of first-line drugs were below therapeutic drug monitoring targets. Rifampicin concentrations were low in all three compartments. Isoniazid, pyrazinamide, and ethambutol achieved higher concentrations in epithelial lining fluid and alveolar cells than plasma. Isoniazid and pyrazinamide concentrations were 14.6 (95% CI: 11.2-18.0) and 49.8-fold (95% CI: 34.2-65.3) higher in lining fluid than plasma respectively. Ethambutol concentrations were highest in alveolar cells (alveolar cells:plasma ratio 15.0, 95% CI 11.4-18.6). Plasma or intrapulmonary pharmacokinetics did not predict clinical treatment response. CONCLUSIONS: We report differential drug concentrations between plasma and the lung. While plasma concentrations were below therapeutic monitoring targets, accumulation of drugs at the site of disease may explain the success of the first-line regimen. The low rifampicin concentrations observed in all compartments lend strong support for ongoing clinical trials of high-dose rifampicin regimens

Evidence for phage-mediated gene transfer among Pseudomonas aeruginosa strains on the phylloplane

As the use of genetically engineered microorganisms for agricultural tasks becomes more frequent, the ability of bacteria to exchange genetic material in the agricultural setting must be assessed. Transduction (bacterial virus-mediated horizontal gene transfer) is a potentially important mechanism of gene transfer in natural environments. This study investigated the potential of plant leaves to act as surfaces on which transduction can take place among microorganisms. Pseudomonas aeruginosa and its generalized transducing bacteriophage F116 were used as a model system. The application of P. aeruginosa lysogens of F116 to plant leaves resulted in genetic exchange among donor and recipient organisms resident on the same plant. Transduction was also observed when these bacterial strains were inoculated onto adjacent plants and contact was made possible through high-density planting.Peer reviewedMicrobiology and Molecular Genetic

Perceptions of research bronchoscopy in Malawian adults with pulmonary tuberculosis : a cross-sectional study

Funding: Liverpool Integrated Clinical Academic Training Programme, experience at another institution (ADM); Wellcome Trust Clinical PhD Fellowship 105392/B/14/Z.Bronchoscopy is an established research tool in Malawi, enabling collection of pulmonary samples for immunological, pharmacological, and microbiological studies. It is, however, an invasive clinical procedure that offers no direct benefit to volunteering participants when used in a research capacity alone, and thus informed consent is essential. This study aimed to explore TB patients' understanding of research bronchoscopy, what would motivate them to participate in research bronchoscopy, and their concerns, in order to inform consenting processes for future clinical studies. We used a qualitative research design. Two focus group discussions were conducted with community members and TB patients to understand their perceptions of bronchoscopy. Transcripts were coded by multiple coauthors and thematic content analysis was used to analyse main findings. We found that Malawian patients with pulmonary TB were willing to participate in a study using research bronchoscopy for health assessment and access to improved healthcare. We identified information of value to potential participants when consenting to that may lessen some of the anxieties expressed by participants. Patient and public involvement is essential to improve informed consent and institutional trust.Publisher PDFPeer reviewe