PrimeStore MTM and OMNIgene Sputum for the Preservation of Sputum for Xpert MTB/RIF Testing in Nigeria

Abstract

Background: Xpert MTB/RIF (GX) for tuberculosis (TB) diagnosis is often located in reference laboratories, and sputum needs to be transported using a cold chain. Transport media to preserve sputum are available, but performance data under programmatic conditions are limited. Methods: Sputum samples were collected from patients with presumptive TB in Nigeria. One sputum was transported in a cold chain, tested immediately with GX and cultured. One sputum was swabbed and stored in PrimeStore-Molecular-Transport-Medium (Primestore), and the remainder was stored in OMNIGene-sputum (Omnigene), kept for seven days and tested with GX. Results: Of 248 patients, 63 were fresh-sputum culture-positive and 56 GX-positive (sensitivity 88.9%, 95% CI: 78.4–95.4%). Four of 185 culture-negative patients were GX-positive (specificity 97.8%, 94.6–99.4%). Omnigene GX and Primestore GX were positive in 56/62 (90.3%, 80.1–96.4%) and 49/62 (79.0%, 66.8–88.3%) culture-positive, respectively, and 1/185 (99.5%, 97.0–100.0%) and 3/185 (98.4%, 95.3–99.7%) were culture-negative patients. 14 Human Immunodeficiency Virus (HIV)-infected and 44 HIV-uninfected patients were culture-positive. Omnigene and Primestore detected 12/14 (85.7%, 57.2–98.2%) and 5/14 (35.7%, 12.8–64.9%) HIV-infected and 41/44 (93.2%, 81.3–98.6%) HIV-uninfected culture-positive patients. Interpretation: Omnigene stored and fresh sputum samples had similar GX results. The GX results of Primestore-stored samples were similar to those found in the fresh sputum of non-HIV infected patients, but GX-positivity was lower in HIV-infected patients. This was likely due to the lower amount of bacilli collected by the swab and transferred to PrimeStore.

Evaluation of Commercially Available Viral Transport Medium (VTM) for SARS-CoV-2 Inactivation and Use in Point-of-Care (POC) Testing

“…Several commercially available Viral Transport Mediums (VTMs) contain a chemical inactivation ingredient. These include the Primestore ® Molecular Transport Medium (MTM) [ 6 ], which is a United States Food and Drug Administration (FDA)-registered VTM (USA) that has been demonstrated to effectively inactivate and preserve multiple pathogens, including mycobacterium tuberculosis (MTB) [ 7 ] and influenza virus [ 8 ], and does not compromise the sensitivity of the GeneXpert platform in the detection of MTB or first-line MTB rifampicin (RIF) resistance (MTB/RIF assay) [ 9 , 10 ]. COPAN™, another VTM, is registered as a non-propagating transport and culture medium with the FDA but does not contain any inactivating agents [ 11 ].…”

A practical approach to render tuberculosis samples safe for application of tuberculosis molecular bacterial load assay in clinical settings without a biosafety level 3 laboratory

“…The WHO End TB strategy and Stop TB Partnership's Global Plan to End TB have set ambitious target to reduce TB incidences by 90% in 2035 [18,19]. To achieve such milestone it will require, among other tools, rapid implementation of accurate TB diagnostics and monitoring tests in healthcare settings, ensuring their availbility to the widest population of TB patients [20]. To this end, we investigated the effectiveness of Guanidine Thiocyanate (GTC) and heat to inactivate viable M. tb prior to RNA extraction and explore whether these innovative methods may be applied in routine healthcare laboratories for TB-MBLA test.…”

A large-volume sputum dry storage and transportation device for molecular and culture-based diagnosis of tuberculosis

“…15 PrimeStore MTM (Longhorn) is a commercial liquid sputum transport medium that lyses Mtb cells and preserves nucleic acids for molecular testing. 16 There have only been a few studies on dry sputum storage. Compared to transportation in the liquid state, dry storage enhances sample stability by removal of water, and reduces biohazards by minimizing the chances of exposure during transportation.…”