MTBDRplus for the rapid diagnosis of ocular tuberculosis and screening of drug resistance

Abstract

PurposeTimely diagnosis of intraocular tuberculosis (IOTB) along with detection of drug resistance can save many eyes from visual impairment. With the growing incidence of IOTB and rising drug resistance, a reliable diagnostic platform for simultaneous detection of the agent and mutated gene is urgently needed. The MTBDRplus assay was evaluated directly on vitreous fluid samples for the same.Patients and methodsIn a prospective study, The MTBDRplus assay was performed on 127 vitreous fluid samples (77 'study group' comprising cases of presumed ocular tuberculosis and 50 'control group' cases of disease controls (n=25) and non-uveitic controls (n=25)). All samples positive by MTBDRplus assay were subjected to gene sequencing to confirm the mutations for rifampicin and isoniazid resistance.ResultsThe MTBDRplus assay produced a sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 36.36%, 100%, 100%, and 50.50%, respectively, for the detection of IOTB. Among the 28 cases from study group that were positive by MTBDRplus assay, rifampicin resistance was reported in six and isoniazid resistance in two cases. On sequencing of rpoB and katG gene, one case of false rifampicin-resistant by MTBDRplus was found. The other resistant isolates showed concordant mutations between MTBDRplus assay and sequencing.ConclusionThe MTBDRplus assay is an effective tool for the rapid diagnosis of IOTB along with detection of drug resistance, thereby improving the outcome in IOTB.

A Saudi Arabian Public Health Perspective of Tuberculosis

“…The recovery of MTB from IOTB samples is relatively low compared to other molecular assays. GenerXpert has an advantage over MTBDRplus due to its automation which reduces manual errors and contamination, but its confining limitation is that it only detects RIF resistance while the MTBDRplus has the ability to detect the RIF and INH resistance [ 114 ]. The use of gene Xpert ® MTB/RIF has shown good sensitivity, specificity, and accuracy in an Egyptian study which was thus recommended for evaluation of RIF resistance with recommendation of re-standardization of reference in order to obtain more valid results [ 115 ].…”

Clinics of ocular tuberculosis: A review

“…Sharma and colleagues 70 improved this reliance rate by validating a multiplex PCR in TB‐endemic India using IS6110, MPB64 and protein b as target genes, yielding sensitivity of 77.8% and specificity of up to 100% for OTB diagnosis. MTBDRplus assay performed on vitreous fluid samples were able to detect rifampicin and isoniazid resistance, confirmed by rpoB and katG gene sequencing, respectively 71 . Moreover, the total time taken for the MTBDRplus assay from sample preparation to reading results was about 24 hours.…”

“…MTBDRplus assay performed on vitreous fluid samples were able to detect rifampicin and isoniazid resistance, confirmed by rpoB and katG gene sequencing, respectively. 71 Moreover, the total time taken for the MTBDRplus assay from sample preparation to reading results was about 24 hours. Rapid provision of information on drug resistance, without the need for culture, will guide ATT and is potentially useful in explaining paradoxical recurrences of ocular inflammation.…”

Retinitis Due to Infections

“…The sensitivity and specificity of PCR methods were estimated and documented by [71], and sensitivity was ranging from 37.7 to 85.2% and specificity was at a level of 90-100%. The MTBDRplus assay, which was performed on vitreous fluid samples, could detect rifampicin and isoniazid resistance, confirmed by rpoB and katG gene sequencing [76]. Larger studies must be planned and performed to validate the accuracy and reliability of modern PCR methods [67].…”