Evaluation of OMNIgene<sup>®</sup>•SPUTUM reagent for mycobacterial culture

Zallet, Julia; Olaru, Ioana D.; Witt, Anne-Kathrin; Vock, P.; Kalsdorf, Barbara; Andres, Sönke; Hillemann, Doris; Kranzer, Katharina

doi:10.5588/ijtld.17.0020

Cited by 5 publications

(13 citation statements)

References 6 publications

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“…There was only one contaminant on untreated samples at day 0. Previous studies have shown that OM-S-treated samples have a lower contamination rate than untreated counterparts (10,(12)(13)(14)(15)23). In our study, only one contaminant in the untreated group may not explain much about the contribution of OM-S in reducing contamination compared to standard decontamination.…”

Section: Discussioncontrasting

confidence: 72%

“…The negative effect of OM-S on mycobacterial recovery on MGIT has been reported in other studies (13,14). The incompatibility between the reagent and culture, however, has been mainly reported for the MGIT system (7,13,16). One study reported poor recovery of MTC across both MGIT and Lowenstein-Jensen (LJ) media (13).…”

Section: Discussionmentioning

confidence: 67%

“…The incompatibility between the reagent and culture, however, has been mainly reported for the MGIT system (7,13,16). One study reported poor recovery of MTC across both MGIT and Lowenstein-Jensen (LJ) media (13). One study reported improved results in MGIT cultures using samples treated with OM-S for up to 3 weeks, with the only concerns being about a delay in MGIT results (15).…”

Section: Discussionmentioning

confidence: 99%

“…OM-S has the ability to liquefy and decontaminate samples at the same time, offering the possibility to extend their storage until 8 days at temperatures up to 40°C prior to culture inoculation (8). However, studies investigating the effect of OM-S have shown good accuracy but mainly with Lowenstein-Jensen (LJ) culture (10,11), while those using MGIT have reported contrasting results (12)(13)(14)(15).…”

mentioning

confidence: 99%

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Evaluation of OMNIgene Sputum and Ethanol Reagent for Preservation of Sputum Prior to Xpert and Culture Testing in Uganda

et al. 2019

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Xpert MTB/RIF (Xpert) and culture are the most reliable methods for tuberculosis diagnosis but are still poorly accessible in many low-resource countries. We aimed to assess the effects of OMNIgene Sputum (OM-S) and ethanol in preserving sputum for Xpert and OM-S for mycobacterial growth indicator tube (MGIT) testing over periods of 15 and 8 days, respectively. Sputum samples were collected from newly diagnosed smear-positive patients. For Xpert, pooled samples were split into 5 aliquots: 3 for Xpert on days 0, 7, and 15 without additive and 2 with either OM-S or ethanol at day 15. For MGIT, 2 aliquots were tested without preservative and 2 with OM-S at 0 and 8 days. Totals of 48 and 47 samples were included in the analysis for Xpert and culture. With Xpert, using day 0 as a reference, untreated samples stored for 7 and 15 days showed concordances of 45/46 (97.8%) and 46/48 (95.8%). For samples preserved with OM-S or ethanol for 15 days compared with untreated samples processed at day 0 or after 15 days, OM-S concordances were 46/48 (95.8%) and 47/48 (97.9%), while those of ethanol were 44/48 (91.7%) and 45/48 (93.8%). With MGIT, concordances between untreated and OM-S-treated samples were 21/41 (51.2%) at day 0 and 21/44 (47.7%) at day 8. In conclusion, Xpert equally detected tuberculosis in OM-S-treated and untreated samples up to 15 days but showed slightly lower detection in ethanol-treated samples. Among OM-S-treated samples, MGIT positivity was significantly lower than in untreated samples at both time points.

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Section: Discussioncontrasting

confidence: 72%

Section: Discussionmentioning

confidence: 67%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Evaluation of OMNIgene Sputum and Ethanol Reagent for Preservation of Sputum Prior to Xpert and Culture Testing in Uganda

et al. 2019

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“…Omnigene was developed to preserve MTB cells for culture, with a reported viability of eight days [12]. Data on the use of Omnigene for downstream culture are mixed, however, with some studies reporting a reduced positivity when compared with the standard NALC-NaOH [13] and others reporting an equivalent performance [14]. Previous smaller studies have shown Omnigene to be compatible with molecular diagnostics such as GX [9], and our findings confirm that testing Omnigene-preserved samples was as accurate as directly testing fresh sputum samples, with minimal change in the cycle threshold (CT) values obtained.…”

Section: Discussionmentioning

confidence: 99%

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

Bimba

Lawson

Kontogianni

et al. 2019

JCM

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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.

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Storage of Sputum in Cetylpyridinium Chloride, OMNIgene.SPUTUM, and Ethanol Is Compatible with Molecular Tuberculosis Diagnostic Testing

et al. 2019

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We compared cetylpyridinium chloride (CPC), ethanol (ETOH), and OMNIgene.SPUTUM (OMNI) for 28-day storage of sputum at ambient temperature before molecular tuberculosis diagnostics. Three sputum samples were collected from each of 133 smear-positive tuberculosis (TB) patients (399 sputum samples). Each patient’s sputum was stored with either CPC, ETOH, or OMNI for 28 days at ambient temperature, with subsequent rpoB amplification targeting a short fragment (81 bp, GeneXpert MTB/RIF [Xpert]) or a long fragment (1,764 bp, in-house nested PCR). For 36 patients, Xpert was also performed at baseline on all 108 fresh sputum samples. After the 28-day storage (D28), Xpert positivity did not significantly differ between storage methods. In contrast, higher positivity for rpoB nested PCR was obtained with OMNI (n = 125, 94%) than with ETOH (n = 114, 85.7%; P = 0.001). Smears with scanty acid-fast bacilli (AFB) had lower rpoB PCR positivity with ETOH storage (n = 10, 41.7%) than with CPC (n = 16, 66.7%; difference, 25%; 95% confidence interval [CI], 3.5 to 46.5; P = 0.031) or OMNI (n = 16, 69.6%; difference, 26.1%; 95% CI, 3.8 to 48.4; P = 0.031), with no difference between CPC and OMNI. Poststorage, the threshold cycle (CT) values significantly decreased compared to those prestorage with ETOH (difference, −1.1; 95% CI, −1.6 to −0.6; P = 0.0001) but not with CPC (P = 0.915) or OMNI (P = 0.33). For one patient’s ETOH- and CPC-stored specimens with a CT of <10, Xpert gave results of rifampin false resistant at D28, which was resolved by repeating Xpert on a 1/100 diluted specimen. In conclusion, 28-day storage of sputum in OMNI, CPC, or ETOH at ambient temperature does not impact short-fragment PCR (Xpert), including for low smear grades. However, for long-fragment PCR, ETOH yielded a lower PCR positivity for low smear grades, while the performance of OMNI and CPC was excellent for all smear grades. (The study has been registered at ClinicalTrials.gov under registration number NCT02744469.)

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Evaluation of OMNIgene^®•SPUTUM reagent for mycobacterial culture

Abstract: Low mycobacterial recovery, especially in MGIT, observed in the present study suggests that OM-S reagent might not be compatible with the MGIT system. More extensive field evaluations of the OM-S reagent are warranted to demonstrate a significant benefit over currently used methods.

Cited by 5 publications

References 6 publications

Evaluation of OMNIgene Sputum and Ethanol Reagent for Preservation of Sputum Prior to Xpert and Culture Testing in Uganda

Evaluation of OMNIgene Sputum and Ethanol Reagent for Preservation of Sputum Prior to Xpert and Culture Testing in Uganda

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

Storage of Sputum in Cetylpyridinium Chloride, OMNIgene.SPUTUM, and Ethanol Is Compatible with Molecular Tuberculosis Diagnostic Testing

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Evaluation of OMNIgene®•SPUTUM reagent for mycobacterial culture

Abstract: Low mycobacterial recovery, especially in MGIT, observed in the present study suggests that OM-S reagent might not be compatible with the MGIT system. More extensive field evaluations of the OM-S reagent are warranted to demonstrate a significant benefit over currently used methods.

Cited by 5 publications

References 6 publications

Evaluation of OMNIgene Sputum and Ethanol Reagent for Preservation of Sputum Prior to Xpert and Culture Testing in Uganda

Evaluation of OMNIgene Sputum and Ethanol Reagent for Preservation of Sputum Prior to Xpert and Culture Testing in Uganda

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

Storage of Sputum in Cetylpyridinium Chloride, OMNIgene.SPUTUM, and Ethanol Is Compatible with Molecular Tuberculosis Diagnostic Testing

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Evaluation of OMNIgene^®•SPUTUM reagent for mycobacterial culture