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. 2019 Dec 4;8(12):2146.
doi: 10.3390/jcm8122146.

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

John S Bimba  1 , Lovett Lawson  1   2 , Konstantina Kontogianni  3 , Thomas Edwards  3 , Bassey Emanna Ekpenyong  1 , James Dodd  4 , Emily R Adams  3 , Derek J Sloan  5 , Jacob Creswell  6 , Jose Dominguez  7 , Luis E Cuevas  3   4
Affiliations

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

John S Bimba et al. J Clin Med. .

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.

Keywords: OMNIGene-sputum; PrimeStore; Xpert MTB/RIF; diagnosis; tuberculosis.

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Conflict of interest statement

The authors have no conflicts of interest to declare. The manufacturers of PrimeStore MTM and OMNIgene (DNA Genotek Inc. and Longhorn Vaccines and Diagnostics) were informed of the results of the study and were invited to provide feedback. However, the authors were free to accept or reject suggestions and to provide the final interpretation of results.

Figures

Figure 1
Figure 1
Xpert semiquantitative results of fresh, Omnigene-stored and Primestore-stored sputum specimens.
See this image and copyright information in PMC

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