Noncommercial TB tests Brief overview from MSF perspective

“Non-commercial” TB tests Brief overview from MSF perspective Francis Varaine, MSF Retooling Task Force Geneva, 15 -16/01/08

Content Microscopy • Bleach concentration • Auramine staining • FDA staining • 2 slides • Positivity threshold Culture and DST • MODS • Thin-layer agar • Nitrate reductase • Redox indicators • Kudoh method • Slide culture • …. .

Microscopy

Bleach concentration method • Centrifugation or sedimentation increases the sensitivity of the sputum smear microscopy. • Angeby et al. , IJTLD 2004 (literature review) – Recommend the evaluation and introduction of the bleach method in most settings where mycobacterial culture is not performed routinely. • Steingart et al. , Lancet Infect Dis. 2006 (a systematic review) – Centrifugation with any of several chemical methods (including bleach) is more sensitive, that overnight sedimentation preceded – There were insufficient data to determine the value of sputum processing methods in patients with HIV infection. • Bonnet et al (MSF), CID 2008. – Bleach sedimentation: An opportunity to optimize tuberculosis smear microscopy in high HIV prevalence settings. Adopted, introduced and implemented

Auramine staining • Steingart et al. , Lancet Infect Dis. 2006 : Fluorescence versus conventional sputum smear microscopy for tuberculosis: a systematic review. – Fluorescence microscopy is more sensitive than conventional microscopy, and has similar specificity. – There is sufficient evidence to determine the value of fluorescence microscopy in HIV-infected individuals • LED • Study in Kenya : bleach + auramine Adopted, introduced and implemented

FDA staining • FDA (fluorescein) staining can be distinguish between live and dead AFB • For diagnosis of true treatment failure. • A. Hamid Salim, et al. , Int J Tuber Lung Dis 2006. Early and rapid microcopybased diagnosis of true treatment failure and MDR-TB. • In Bangladesh: Compared FDA staining and culture on smear positive sputum. -Sensitivity 99% -Specificity 82% -Accuracy 93% Operational research

New definitions • 2 slides • Positivity threshold : – 1 positive / 2 slides – 1 AFB / 100 fields Bonnet, et al : Reducing the number of sputum samples examined and thresholds for positivity: an opportunity to optimise smear microscopy. IJTLD (2007) Adopted, introduced and implemented

Rapid culture and DST • Microcolonies • Colorimetric methods

MODS Microscopic observation drug susceptibility Based on characteristic cord formation in early liquid cultures • Caviedes et al. JCM 2000; Moore et al. JCM 2004, NEJM 2006 • MTB detection rapid (median 7 days, 13 days BACTEC, 26 days LJ) • Sensitive (98% vs 84%) • RIF: sensitivity 100%; specificity 100% • INH: sensitivity 84, 6%; specificity 99. 6% Caviedes et al. J. Clin Microbiol 2000 Not adopted

MODS procedure manual http: //www. ucph. edu. pe

TLA Thin Layer Agar Based on detection of microcolonies on 7 H 10 agar Characteristic “cording” • Robledo et al. , IJTLD 2006 (multicenter study) • Da Silva et. al. , Braz. J. of Microbiology 2007 • Direct method for smear positive and negative specimens • Median time to detection 10 days, for RIF and INH resistance • Good sensitivity and specificity for direct DST (Robledo et al. , submitted) Picture: J. Robledo Adopted for field testing

TLA multicentric study Total of 1118 specimens studied in six sites Evaluation of a rapid culture method for tuberculosis diagnosis: a Latin American multi-center study. J. A. Robledo, G. I. Mejía, N. Morcillo, L. Chacón M. Camacho, J. Luna, J. Zurita, A. Bodon, M. Velasco, J. C. Palomino, A. Martin, F. Portaels. Int. J. Tuberc. Lung. Dis. 10(6): 613– 619, 2006

TLA for diagnosis 7 H 11 Decontamination sputum sample NALC/Na. OH 7 H 11 + PNB Reading with standard microscope Identification M. tuberculosis

Direct DST TLA INH/RIF Identification M. tuberculosis 7 H 11 agar growth control Decontamination sputum sample 7 H 11 agar + INH 0. 2 7 H 11 agar +PNB 500 7 H 11 agar + RIF 1 37°C 5%C 02 Reading with standard microscope Detection resistance INH Detection resistance RIF + ofloxacine under validation

Implementation of TLA in Homa Bay, Kenya (MSF)

TB culture lab.

Reading under normal microscope (objective 10 x), twice a week

TLA procedure manual http: //www. itg. be

Rapid culture and DST • Microcolonies • Colorimetric methods

Nitrate Reductase Assay (Griess method) NRA (indirect) • Ängeby et al. , JCM 2002, • Martin et al. , JMM 2005 (multicentric study first-line drugs), • Martin et al. , JCM, 2005 (ofloxacin) • INH, RIF, EMB, SM, OFLO • High accuracy (95 -100%) for INH, RIF and OFLO • Median TAT: 10 days NRA (direct) on sputum smear + samples • Musa et al. J Clin Microbiol 2005 • Solis et al. Int J Tuberc Lung Dis 2005 • Affolabi et al. J Clin Microbiol 2007 • Median TAT: 14 -28 days Considered for field testing

Nitrate Reductase Assay (Griess method) Nitrate Nitrite

Implementation of the NRA direct in Cotonou • • • Affolabi et al, JCM 2007 Performed on solid media Rapid method for DST Easy to implement in resource-limited countries No need for training if implemented in lab where DST is already performed on LJ. • No need of special equipment • Sensitivity 88%, specificity 100% • TAT: 18 days (direct)

Picture: Dr Affolabi, Benin

Colorimetric redox indicators • Based on reduction of indicators by mycobacterial metabolism – Alamar Blue (Yaiko et. al JCM 1995) – Resazurin (Palomino, AAC 2002) • Martin et al. 2007 meta-analysis – 18 studies for RIF – 16 studies for INH • Evidence of high sensitivity and specificity • Other studies: EMB, SM, KAN, ETH, CAP, OFLO MIC Picture: A. Martin

Implementation of the resazurin in Cotonou Affolabi et al. , 2007 (submitted) • • Studied 151 strains of TB Performed REMA and compared results with the gold standard PM on LJ for RIF and INH • • TAT REMA : 3 weeks + 8 days Conventional method : 3 weeks + 4 -6 weeks. • Results – for RIF: 94% sensitivity and 100% specificity – for INH: 100 % sensitivity and 100% specificity

NRA procedure manual http: //www. itg. be

Colorimetric assay procedure manual http: //www. itg. be

Simplified culture

Kudoh culture – Swab method • Kudoh and Kudoh. Bull. World Health Org. 1974; 51: 71 -82 : a simplified swab method for culturing mycobacteria that takes only 3 -4 minutes per sample, and needs neither technical skill, centrifugation, nor a biosafety cabinet. • Sputum is smeared onto a swab stick that is immersed into a test tube with sterile 4% sodium hydroxide. • Very simple method to culture Mycobacteria in rural areas • In 2006: evaluation of this method in Venezuela (Jacobus De. Waard, unpublish data) • Kudoh swab method is as sensitive as the Petroff decontamination procedure in the diagnosis of pulmonary TB. . 4% Na. OH Medium Ogawa p. H 6, 4

Implementation of Kudoh culture in Venezuela, Warao Amerindian population Jacobus De Waard et al. (not yet published) • • Evaluation of the Kudoh method in two hospital laboratories in Caracas, Venezuela and in the Warao Amerindian population (Orinoco River delta). All samples were processed for acid-fast staining and cultured using both the Petroff and Kudoh methods. Picture: Jacobus De Waard, Venezuela

Results: Kudoh culture Jacobus De Waard et al. (unpublished) No. of sputum Samples Acid-fast staining smear + Culture Kudoh Hospital setting 315 56 71 Field conditions 651 38 46 • • • Culture Petroff 68 N. D Positive Total 77 46 Kudoh swab method is as sensitive as the Petroff decontamination procedure in the diagnosis of pulmonary TB. It represents an alternative method for culturing mycobacteria that could reduce labor in laboratories with a high volume of sputum samples, especially appropriate for rural settings without the proper infrastructure for traditional culturing. The method needs no laboratory equipment, and the minimal sample manipulation reduces biosecurity risks, so that it can be easily taught to technicians without experience in tuberculosis microbiology. Considered for operational research

Slide DST

Slide DST • Culture perform directly on slide smear-positive samples • Counting acid-fast micro-colonies under microscope • A. Hamid Salim et al. , Int J Tuber Lung Dis 2006. Early and rapid microcopybased diagnosis of true treatment failure and MDR-TB. • Sensitivity and specificity RIF: 96% • Sensitivity and specificity INH: 99% and 64% Picture: A. van Deun Considered for operational research

Early and rapid microcopy-based diagnosis of true treatment failure and MDR-TB, 2006, Int J Tuber Lung Dis 10 (11): 1248 -1254. A. Hamid Salim, et al

Summary Microscopy • Bleach concentration • Auramine staining • FDA staining • 2 slides • Positivity threshold Implemented Operational research Implemented Culture and DST • MODS • Thin-layer agar • Nitrate reductase • Redox indicators • Kudoh method • Slide culture Not adopted Adopted for field test Considered for field test Not adopted Considered for operational research

Conclusion • Some tools exist – Some ready for implementation – Some require more field testing – Some require more evidence • Why so slow ? • Why so neglected ?