A field evaluation of the Hardy TB MODS Kit™ for the rapid phenotypic diagnosis of tuberculosis and multi-drug resistant tuberculosis.

BACKGROUND: Even though the WHO-endorsed, non-commercial MODS assay offers rapid, reliable TB liquid culture and phenotypic drug susceptibility testing (DST) at lower cost than any other diagnostic, uptake has been patchy. In part this reflects misperceptions about in-house assay quality assurance, but user convenience of one-stop procurement is also important. A commercial MODS kit was developed by Hardy Diagnostics (Santa Maria, CA, USA) with PATH (Seattle, WA, USA) to facilitate procurement, simplify procedures through readymade media, and enhance safety with a sealing silicone plate lid. Here we report the results from a large-scale field evaluation of the MODS kit in a government service laboratory. METHODS & FINDINGS: 2446 sputum samples were cultured in parallel in Lowenstein-Jensen (LJ), conventional MODS and in the MODS kit. MODS kit DST was compared with conventional MODS (direct) DST and proportion method (indirect) DST. 778 samples (31.8%) were Mycobacterium tuberculosis culture-positive. Compared to conventional MODS the sensitivity, specificity, positive, and negative predictive values (95% confidence intervals) of the MODS Kit were 99.3% (98.3-99.8%), 98.3% (97.5-98.8%), 95.8% (94.0-97.1%), and 99.7% (99.3-99.9%). Median (interquartile ranges) time to culture-positivity (and rifampicin and isoniazid DST) was 10 (9-13) days for conventional MODS and 8.5 (7-11) for MODS Kit (p<0.01). Direct rifampicin and isoniazid DST in MODS kit was almost universally concordant with conventional MODS (97.9% agreement, 665/679 evaluable samples) and reference indirect DST (97.9% agreement, 687/702 evaluable samples). CONCLUSIONS: MODS kit delivers performance indistinguishable from conventional MODS and offers a convenient, affordable alternative with enhanced safety from the sealing silicone lid. The availability in the marketplace of this platform, which conforms to European standards (CE-marked), readily repurposed for second-line DST in the near future, provides a fresh opportunity for improving equity of access to TB diagnosis and first and second-line DST in settings where the need is greatest

Analysis of age-dependent trends in Ov16 IgG4 seroprevalence to onchocerciasis

BACKGROUND: Diagnostics provide a means to measure progress toward disease elimination. Many countries in Africa are approaching elimination of onchocerciasis after successful implementation of mass drug administration programs as well as vector control. An understanding of how markers for infection such as skin snip microfilaria and Onchocerca volvulus-specific seroconversion perform in near-elimination settings informs how to best use these markers. METHODS: All-age participants from 35 villages in Togo were surveyed in 2013 and 2014 for skin snip Onchocerca volvulus microfilaria and IgG4 antibody response by enzyme-linked immunosorbent assay (ELISA) to the Onchocerca volvulus-specific antigen Ov16. A Gaussian mixture model applying the expectation-maximization (EM) algorithm was used to determine seropositivity from Ov16 ELISA data. For a subset of participants (n = 434), polymerase chain reaction (PCR) was performed on the skin snips taken during surveillance. RESULTS: Within the 2,005 participants for which there was Ov16 ELISA data, O. volvulus microfilaremia prevalence and Ov16 seroprevalence were, 2.5 and 19.7 %, respectively, in the total population, and 1.6 and 3.6 % in children under 11. In the subset of 434 specimens for which ELISA, PCR, and microscopy data were generated, it was found that in children under 11 years of age, the anti-Ov16 IgG4 antibody response demonstrate a sensitivity and specificity of 80 and 97 %, respectively, against active infections as determined by combined PCR and microscopy on skin snips. Further analysis was performed in 34 of the 35 villages surveyed. These villages were stratified by all-age seroprevalence into three clusters: < 15 %; 15–20 %; and > 20 %. Age-dependence of seroprevalence for each cluster was best reflected by a two-phase force-of-infection (FOI) catalytic model. In all clusters, the lower of the two phases of FOI was associated with a younger age group, as reflected by the seroconversion rates for each phase. The age at which transition from lower to higher seroconversion, between the two phases of FOI, was found to be highest (older) for the cluster of villages with < 15 % seroprevalence and lowest (younger) for the cluster with the highest all-age seroprevalence. CONCLUSIONS: The anti-Ov16 IgG4 antibody response is an accurate marker for active infection in children under 11 years of age in this population. Applying Ov16 surveillance to a broader age range provides additional valuable information for understanding progression toward elimination and can inform where targeted augmented interventions may be needed. Clustering of villages by all-age sero-surveillance allowed application of a biphasic FOI model to differentiate seroconversion rates for different age groups within the village cluster categories. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13071-016-1623-1) contains supplementary material, which is available to authorized users

The Social Determinants of Health as part of the Medical School Curriculum: An Exploratory Analysis of Domestic and International Medical Schools

Thesis (Master's)--University of Washington, 2012The social determinants of health (SDOH) are increasingly recognized as an important topic however it is only recently that the American medical focus has incorporated anything other than biological pathways to health. An ideological shift from our current practice of `disease-care' to a framework that includes the socio-economic environment is challenging. As education is an effective way to influence change it is important to know what American medical students are learning about the SDOH and, more importantly, what are they not learning when compared to medical students outside of the US. To assess the emphasis placed on the social determinants of health in medical education, the curricula of 26 universities were analyzed for key terms to ascertain the presence of the SDOH. Results indicate that American medical students overall have less exposure to the SDOH throughout their required course work when compared to schools outside of the United States. Canadian medical schools in particular integrate these concepts into the majority of a students' coursework. By looking at a snapshot of medical curricula we can understand where medical education in the United States currently stands as well as where it has room to expand. Identifying what gaps exist in medical education will enable curriculum committees to address these gaps to ensure a more holistic medical education for future physicians

Proportion of samples positive by each culture method.

<p>Total samples: N = 2446, culture positive by any method: n = 778 (31.8%), culture negative by all methods: n = 1603 (65.5%), contaminated samples without a positive parallel culture: n = 65 (2.7%).</p

Direct DST result by MODS Kit compared with indirect DST result by proportions method (with discrepant analysis by Genotype MTB-DR plus).

<p>Data in table indicate consolidated reference indirect test result after discrepant analysis employing Genotype MTB-DR plus line probe assay as arbiter test (Genotype MTB-DR plus determined final true result in those samples for which MODS Kit and proportions method were discordant).</p><p>concordant DST, n = 687 (shaded grey).</p><p>discordant DST, n = 15 (no shading).</p><p>Direct DST result by MODS Kit compared with indirect DST result by proportions method (with discrepant analysis by Genotype MTB-DR plus).</p

STARD (STAndards for the Reporting of Diagnostic accuracy) flow diagram for MODS Kit for TB detection.

<p>Kappa value 0.94, agreement 97.4%. +ve = TB culture positive, -ve = TB culture negative. Contaminated & indeterminate results are culture outcomes following reprocessing if necessary according to protocol.</p

A Recombinant Positive Control for Serology Diagnostic Tests Supporting Elimination of Onchocerca volvulus.

Serological assays for human IgG4 to the Onchocerca volvulus antigen Ov16 have been used to confirm elimination of onchocerciasis in much of the Americas and parts of Africa. A standardized source of positive control antibody (human anti-Ov16 IgG4) will ensure the quality of surveillance data using these tests.A recombinant human IgG4 antibody to Ov16 was identified by screening against a synthetic human Fab phage display library and converted into human IgG4. This antibody was developed into different positive control formulations for enzyme-linked immunosorbent assay (ELISA) and rapid diagnostic test (RDT) platforms. Variation in ELISA results and utility as a positive control of the antibody were assessed from multiple laboratories. Temperature and humidity conditions were collected across seven surveillance activities from 2011-2014 to inform stability requirements for RDTs and positive controls. The feasibility of the dried positive control for RDT was evaluated during onchocerciasis surveillance activity in Togo, in 2014. When the anti-Ov16 IgG4 antibody was used as a standard dilution in horseradish peroxidase (HRP) and alkaline phosphatase (AP) ELISAs, the detection limits were approximately 1ng/mL by HRP ELISA and 10ng/mL by AP ELISA. Positive control dilutions and spiked dried blood spots (DBS) produced similar ELISA results. Used as a simple plate normalization control, the positive control antibody may improve ELISA data comparison in the context of inter-laboratory variation. The aggregate temperature and humidity monitor data informed temperature parameters under which the dried positive control was tested and are applicable inputs for testing of diagnostics tools intended for sub-Saharan Africa. As a packaged positive control for Ov16 RDTs, stability of the antibody was demonstrated for over six months at relevant temperatures in the laboratory and for over 15 weeks under field conditions.The recombinant human anti-Ov16 IgG4 antibody-based positive control will benefit inter-laboratory validation of ELISA assays and serve as quality control (QC) reagents for Ov16 RDTs at different points of the supply chain from manufacturer to field use

Additional file 1: Table S1. of Analysis of age-dependent trends in Ov16 IgG4 seroprevalence to onchocerciasis

Village name, number of study participants, Ov16 prevalence and MF prevalence values used to generate Fig. 4b. (DOCX 15 kb