title: A field evaluation of the Hardy TB MODS Kit™ for the rapid phenotypic diagnosis of tuberculosis and multi-drug resistant tuberculosis.
abstract: 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.
  
  
  RESULTS
  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.
authors.affiliation: Laboratorio de Investigación en Enfermedades Infecciosas, Universidad Peruana Cayetano Heredia, Lima, Peru; Wellcome Centre for Clinical Tropical Medicine, Imperial College of Science, Technology and Medicine, London, United Kingdom.
authors.forename: Laura
authors.initials: L
authors.lastname: Martin
authors.affiliation: Laboratorio de Investigación en Enfermedades Infecciosas, Universidad Peruana Cayetano Heredia, Lima, Peru.
authors.forename: Jorge
authors.initials: J
authors.lastname: Coronel
authors.affiliation: PATH, Seattle, Washington, United States of America.
authors.forename: Dunia
authors.initials: D
authors.lastname: Faulx
authors.affiliation: PATH, Seattle, Washington, United States of America.
authors.forename: Melissa
authors.initials: M
authors.lastname: Valdez
authors.affiliation: PATH, Seattle, Washington, United States of America.
authors.forename: Mutsumi
authors.initials: M
authors.lastname: Metzler
authors.affiliation: PATH, Seattle, Washington, United States of America.
authors.forename: Chris
authors.initials: C
authors.lastname: Crudder
authors.affiliation: Laboratorio de Salud Pública de la Dirección Regional de Salud del Callao, Lima, Peru.
authors.forename: Edith
authors.initials: E
authors.lastname: Castillo
authors.affiliation: Laboratorio de Investigación en Enfermedades Infecciosas, Universidad Peruana Cayetano Heredia, Lima, Peru.
authors.forename: Luz
authors.initials: L
authors.lastname: Caviedes
authors.affiliation: Laboratorio de Investigación en Enfermedades Infecciosas, Universidad Peruana Cayetano Heredia, Lima, Peru; Wellcome Centre for Clinical Tropical Medicine, Imperial College of Science, Technology and Medicine, London, United Kingdom.
authors.forename: Louis
authors.initials: L
authors.lastname: Grandjean
authors.affiliation: Laboratorio de Salud Pública de la Dirección Regional de Salud del Callao, Lima, Peru.
authors.forename: Mitzi
authors.initials: M
authors.lastname: Rodriguez
authors.affiliation: Wellcome Centre for Clinical Tropical Medicine, Imperial College of Science, Technology and Medicine, London, United Kingdom.
authors.forename: Jon S
authors.initials: JS
authors.lastname: Friedland
authors.affiliation: Laboratorio de Investigación en Enfermedades Infecciosas, Universidad Peruana Cayetano Heredia, Lima, Peru; Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Gilman
authors.affiliation: Laboratorio de Investigación en Enfermedades Infecciosas, Universidad Peruana Cayetano Heredia, Lima, Peru; Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America; TB Centre and Department of Clinical Research, London School of Hygiene & Tropical Medicine, London, United Kingdom.
authors.forename: David A J
authors.initials: DA
authors.lastname: Moore
mesh_terms: D000995:Antitubercular Agents / Q000494:pharmacology; D006801:Humans; D007538:Isoniazid / Q000494:pharmacology; D008826:Microbial Sensitivity Tests / Q000379:methods*; D009169:Mycobacterium tuberculosis / Q000187:drug effects; D010568:Peru; D011933:Reagent Kits, Diagnostic; D015203:Reproducibility of Results; D012293:Rifampin / Q000494:pharmacology; D012680:Sensitivity and Specificity; D013183:Sputum / Q000382:microbiology; D014376:Tuberculosis / Q000175:diagnosis*; D018088:Tuberculosis, Multidrug-Resistant / Q000175:diagnosis*
chemical_list: D000995:Antitubercular Agents; D011933:Reagent Kits, Diagnostic; D007538:Isoniazid; D012293:Rifampin