Do Xpert MTB/RIF Cycle Threshold Values Provide Information about Patient Delays for Tuberculosis Diagnosis?

Ssengooba, Willy; Respeito, Durval; Mambuque, Edson; Blanco, Silvia; Bulo, Helder; Mandomando, Inácio; Jong, Bouke C. de; Cobelens, Frank; García‐Basteiro, Alberto L.

doi:10.1371/journal.pone.0162833

Cited by 17 publications

(23 citation statements)

References 24 publications

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“…lower Ct values represent a higher starting concentration of DNA template whereas higher Ct values represent a lower concentration of DNA template. The mean Ct values is categorized by the Xpertassay semi-quantitatively in relation to sample positivity as very low (>28 cycles), low (23-28 cycles), medium(16-22 cycles) and high (<16 cycles) 13 . In our study out of 5 positive samples by GeneXpert, 2 samples were medium positive and 3 samples were very low positive indicating paucibacillary nature of genital tuberculosis.…”

Section: Discussionmentioning

confidence: 99%

GeneXpert positivity and evaluation of rifampicin resistance among endometrial biopsy specimens for the diagnosis of Genital Tuberculosis

Kashyap¹,

Dibyashree²,

Saha³

et al. 2020

OBGYN

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Objective: The aim of this study was to find out the GeneXpert positivity among endometrial biopsy specimens for diagnosis of genital tuberculosis. Materials and Methods: A retrospective study was conducted from January 2019 to June 2019 on all women clinically and radiologically diagnosed with infertility, dyspareunia, menstrual irregularities and pelvic inflammatory disease. Endometrial biopsies were taken from all cases and subjected to GeneXpert test for detection of Mycobacterium tuberculosis. Result: Total number of suspected cases was 62 with age ranging from 19 years to 65 years. Majority of suspected cases were from the age group 21-30 years (54.8%). Five out of 62 (8%) cases tested positive for Mycobacterium tuberculosis by GeneXpert which were all sensitive to Rifampicin. Among these 5 cases, 2 were reported as medium positive and 3 as very low positive based on cycle threshold value. Conclusion: GeneXpert on endometrial biopsy may prove to be a reliable diagnostic modality for genital tuberculosis as well as multidrug resistance tuberculosis in females leading to timely management of the disease.

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Section: Discussionmentioning

confidence: 99%

GeneXpert positivity and evaluation of rifampicin resistance among endometrial biopsy specimens for the diagnosis of Genital Tuberculosis

Kashyap¹,

Dibyashree²,

Saha³

et al. 2020

OBGYN

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“…Included participants were passively followed-up for a period of 2 years. This analysis was nested in the TOSSE study, a surveillance project which aimed at improving TB diagnosis and reporting in the district of Manhiça 20 .…”

Section: Methodsmentioning

confidence: 99%

Mortality and risk of tuberculosis among people living with HIV in whom TB was initially ruled out

García

Mambuque

Nguenha

et al. 2020

Sci Rep

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Tuberculosis (TB) misdiagnosis remains a public health concern, especially among people living with HIV (PLHIV), given the high mortality associated with missed TB diagnoses. The main objective of this study was to describe the all-cause mortality, TB incidence rates and their associated risk factors in a cohort of PLHIV with presumptive TB in whom TB was initially ruled out. We retrospectively followed a cohort of PLHIV with presumptive TB over a 2 year-period in a rural district in Southern Mozambique. During the study period 382 PLHIV were followed-up. Mortality rate was 6.8/100 person-years (PYs) (95% CI 5.2–9.2) and TB incidence rate was 5.4/100 PYs (95% CI 3.9–7.5). Thirty-six percent of deaths and 43% of TB incident cases occurred in the first 12 months of the follow up. Mortality and TB incidence rates in the 2-year period after TB was initially ruled out was very high. The TB diagnostic work-up and linkage to HIV care should be strengthened to decrease TB burden and all-cause mortality among PLHIV with presumptive TB.

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“…During detection, the valid maximum cycle threshold (CT) was 39.0 for Probes A, B and C and 36.0 for Probes D and E. The MTB is detected when at least two probes result in CT values within the valid range and a delta CT min of less than 2.0. Depending on the CT value, the MTB is semi-quantified into very low, low, medium and high for CT values of >28, 23–28, 16–22 and <16 cycles respectively [ 19 ]. Similarly, the assay does not detect MTB when there is only one or no positive probe.…”

Section: Methodsmentioning

confidence: 99%

Improved performance of Xpert MTB/RIF assay on sputum sediment samples obtained from presumptive pulmonary tuberculosis cases at Kibong’oto infectious diseases hospital in Tanzania

Mbelele

Aboud

Mpagama³

et al. 2017

BMC Infect Dis

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BackgroundThe introduction of Xpert MTB/RIF assay (Xpert) has significantly improved diagnosis of Tuberculosis (TB) in resource limited human immunodeficiency virus (HIV) endemic settings. We aimed to modify the Xpert protocol to improve the detection of Mycobacterium tuberculosis (MTB).MethodsThis cross sectional study was conducted among presumptive pulmonary tuberculosis (PTB) patients at Kibong’oto Infectious Diseases Hospital between August and November 2015. Each patient consented to provide 2 samples of raw sputa. One-sputum sample was sedimented using the Petroff’s method and divided into two portions. One portion of sediment was inoculated on Lowenstein-Jensen culture media and observed for any growth for up to 8 weeks. Both, raw sputum and the portions of sediments were tested separately using Xpert with a sample reagent ratio of 1:2. Mean age of patients, prevalence of MTB, Xpert sensitivity, specificity, positive and negative predictive value were calculated. An incremental sensitivity was determined. Pearson chi-square and either an independent T or Mann-Whitney U-test were used to compared categorical and continuous variables respectively. A p- value of ≤0.05 was considered significant.ResultsOf the 270 presumptive PTB cases, 262 were eligible for analysis. Eight (3%) were excluded due to contaminated culture. Patients’ mean age was 42.9 (±SD 15.1) years of which 173 (66%) were female. The overall prevalence of PTB was 112 (43%), of which the Xpert detected 105 (40%) in sediments and 98 (37%) in raw sputa as compared to culture which detected 85 (32%) cases of PTB. Sensitivity, specificity, positive and negative predictive values of Xpert on sputum sediments were 92%, 85%, 74% and 96% respectively. Overall, the incremental sensitivity of Xpert on sediment over raw sputum was 6%. In HIV infected Presumptive PTB, the incremental sensitivity was 12%.ConclusionLowering the sample reagent to sediment dilution ratio increases sensitivity of Xpert on MTB detection among presumptive PTB cases, especially in HIV infected individuals.

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Do Xpert MTB/RIF Cycle Threshold Values Provide Information about Patient Delays for Tuberculosis Diagnosis?

Cited by 17 publications

References 24 publications

GeneXpert positivity and evaluation of rifampicin resistance among endometrial biopsy specimens for the diagnosis of Genital Tuberculosis

GeneXpert positivity and evaluation of rifampicin resistance among endometrial biopsy specimens for the diagnosis of Genital Tuberculosis

Mortality and risk of tuberculosis among people living with HIV in whom TB was initially ruled out

Improved performance of Xpert MTB/RIF assay on sputum sediment samples obtained from presumptive pulmonary tuberculosis cases at Kibong’oto infectious diseases hospital in Tanzania

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