ASSESSMENT OF GENEXPERT TEST FOR DIAGNOSIS OF PEDIATRIC PULMONARY TUBERCULOSIS

ROC) analysis was performed to compare the performance of gene Xpert test with other lab parameters like sputum/gastric lavage sample microscopy for acid fast bacilli, erythrocy�c sedimenta�on rate, Tuberculin test (TT) and chest X-ray. Results We enrolled a total of 294 pa�ents in our study. Out of 294 samples 5.1% samples came out to be posi�ve for gene Xpert for MTB. The sputum/gastric lavage samples for AFB showed both sensi�vity and speciﬁcity of 100%. The tuberculin test showed a sensi�vity of 80% and speciﬁcity of 37.3%. Chest X-ray showed a sensi�vity of 66.7% and speciﬁcity of 43.7%. The area under the curve for acid fast bacilli in microscopy, tuberculin test and ESR was found to be 100% (95% CI: 100%-100%), 58.6% (95% CI: 44.9%-72.4%), and 52.6% (95% CI: 37%-68.3%) respec�vely.


INTRODUCTION
Tuberculosis (TB) is an infec ous disease caused by Mycobacterium tuberculosis (MTB) and is one of the top ten cause of death according to the global Tuberculosis Report of World Health Organiza on (WHO).The disease burden of tuberculosis is 10.6 million and is responsible for 1.6 million mortali es annually.Globally 134 cases per 1,00,000 world's popula on is infected with this disease.Out of 10.6 million 1 TB cases 11 percent cases are reported in pediatric pa ents.According to data provided by Ministry of Health and popula on Nepal, 28,677 people tested posi ve for tuberculosis out of an es mated 69,000 new cases in fiscal year 2020-2021 which is around 40 percent of the total es mated new cases.The incidence of pediatric TB is a key tool of ongoing transmission of tuberculosis within the community and vital indicator of disease control.In poorly control areas children contribute 10-20% of disease burden.Na onal TB control center report shows 6.04% of

METHODOLOGY
This was a hospital based prospec ve study done at pediatric department of a teaching hospital, Nepalgunj, Banke.This study was conducted over a period of 1 year from 1 January 2021 to 31 December 2021.All the pa ents who presented to outpa ent department and those admi ed to inpa ent department for workup of pediatric pulmonary tuberculosis during the study period below the age of 15 years were included in this study.Inclusion criteria were presump ve TB cases with symptoms or signs sugges ve of TB i.e. cough for two or more weeks, loss of appe te, malnutri on, fever, weight loss, fa gue, reduced playfulness, lethargy.History of contact with tuberculosis pa ent within the last two years and Chest X-ray findings sugges ve of tuberculosis were included in our study.The exclusion criteria were par cipants having comorbidi es or who were previously diagnosed with TB, those suspected of extra-pulmonary tuberculosis, unwillingness to par cipate in the study and children with other causes of fever and cough such as lower respiratory tract infec on, asthma etc.A detailed clinical history and examina on for pulmonary tuberculosis was done.The gastric lavage samples were collected as per standards.For the collec on of sample pa ents were called early in the morning with at least 4 hours nil per mouth before the procedure.Counselling and consent of parents/child was done before the procedure.then child was posi oned on his/her back and immobilized by rapping in the sheet of cloth.Distance between the earlobe -nose and xphi-sternum was measured and marked.Lignocaine jelly was applied in the NG tube and the tube was gently inserted up to the measured length via the nose and advanced into the stomach and posi on of the tube was confirmed by ausculta on by pushing 3-5ml of air via syringe.gastric content 2-5 ml were withdrawn by NG tube and obtained fluid was transferred in a sterile container.Inves ga ons done were: (i) Sputum/gastric lavage sample microscopy for AFB-demonstra on of AFB is diagnos c of tuberculosis (ii) Tuberculin test (TT) (Arkray Healthcare Pvt.Ltd, Surat, India)-indura on more than 10 mm is posi ve, indura on more than 5mm is considered as posi ve in children with malnutri on ,immunosuppression and HIV (iii) Chest X-ray-findings on chest x-ray like pleural effusion, consolida on, hilar lymphadenopathy, military mo ling etc. were considered as posi ve finding.(iv) Gene Xpert (on sputum/ gastric lavage specimens) using the automated real-me DNA amplifica on test for rapid detec on of TB (XPERT® MTB/RIF assay; Cephid Invitro Diagnos cs).Gene Xpert test is done free of cost at our center and is supported by Na onal tuberculosis center, Kathmandu.The sta s cal package program SPSS version 20 was used to analyze data.Con ngency tables were used to display data of different categorical variables.Chi-square test was used to determine the associa on between categorical variables and ROC analysis was performed to compare performance of gene Xpert test with other lab parameters.P value less than or equal to 0.05 was regarded as sta s cally significant.Sensi vity, specificity of AFB microscopy and Xpert MTB/RIF assay were also calculated.The study was approved by the Ethical Commi ee.The parents/guardians on behalf of the children and

RESULTS
The present study was done to assess the u lity of the gene Xpert test for diagnosis of pediatric pulmonary tuberculosis.We enrolled a total of 294 pa ents in our study mee ng the inclusion criteria during the study period presen ng to outpa ent department or admi ed to pediatric inpa ent department.The study subjects comprised of 55.4% males and remaining were females.51% pa ents belonged to the age group of 6-10 years followed by 38.8% pa ent belonging to the age group of 11-15 years and minimum number of pa ents belonged from the age group of less than 1 year which comprised of 0.7% pa ents.The clinical and laboratory parameters of suspected pediatric pulmonary tuberculosis pa ents are elaborated in table 1.
Out of 294 samples 15(5.1%)samples came out to be posi ve for gene Xpert for MTB.The sputum/gastric lavage samples for AFB showed both sensi vity and specificity of 100%.The tuberculin test showed a sensi vity of 80% and specificity of 37.3%.The chest X-ray showed a sensi vity of 66.7% and specificity of 43.7%.The ESR showed a low sensi vity of 6.7% and specificity of 98.6% in our study.A receiver opera ng curve (ROC) analysis was performed.As shown in figure 3, area under curve for AFB was found to be 100%.Area under curve for tuberculin test was found to be 58.6% at 95% CI with lower bound 44.9% and upper bound 72.4%.The area under curve for ESR was found to be 52.6% at 95% CI with lower bound 37% and upper bound 68.3%.The area under curve for Chest X-ray was found to be 55.2% at 95% CI with lower bound to be 40.6% and upper bound 69.8%.

DISCUSSION
Worldwide pediatric tuberculosis is associated with high mortality, its clinical features are subtle in children.There is lack of quick and reliable modali es making TB diagnosis further challenging.The gene Xpert test can be a rapid alterna ve diagnos c modality for diagnosis for pediatric pulmonary TB.The Gene Xpert test is cartridge based real me PCR detec on which is very sensi ve and result are

CONCLUSION
This study highlights the u lity of gene Xpert as a good diagnos c tool for rapid diagnosis of tuberculosis in pediatric popula on in low resource se ng like ours.

RECOMMENDATIONS
As per findings from this study we found gene Xpert test is be er for early detec on of pediatric pulmonary tuberculosis.So we recommend access of this test as burden of tuberculosis is high.

LIMITATIONS OF THE STUDY
This study was a single center study on a sample size of 294 only, if we could do such mul -centric study on much larger sample size then we would be able to generalize the findings represen ng real scenario.Gene Xpert test is an expensive test so mul -centric study would only be possible if this test will be provided free to the pa ents otherwise cost of the test would be a limita on.

Table 2 : 3 :Figure 1 :
Diagnos c accuracy of ESR, CXR, TT and sputum/gastric lavage AFB Table Area under curve of various lab parameters *MT (Mantoux test ), **AFB (Acid fast bacilli) ROC curve diagnos c accuracy of various lab parameters of tuberculosis.
2,3tuberculosis burden in pediatric popula on in Nepal.Many cases of tuberculosis are missed by the health care workers leading to deaths because of delayed diagnosis.Efforts are being made to diagnose the missing cases to increase TB diagnosis and to provide mely treatment to save lives.Gene Xpert is more accurate than smear 4 microscopy.Clinical picture of tuberculosis in children is very nonspecific and is different from adults with minor changes like weight loss, failure to gain weight, poor appe te, fa gue, disinclina on to play etc. which is usually So, there is need of an accurate, rapid and feasible tuberculosis diagnos c test in the resource limited se ng like ours for control of TB.Gene Xpert test is a molecular test which detects DNA of the tubercle bacillus, takes about 2 hours to obtain results and is highly specific 6and sensi ve test.

Table 1 .
Clinical, laboratory variables of suspected pediatric TB cases.adolescentsincluded in this study had given wri en informed consent to par cipate in the study.
13,14 available in two hours.So, we have assessed u lity of this test in diagnosis of pediatric pulmonary tuberculosis.We studied 294 pa ents which comprised 55.4% males and remaining were females.Highest numbers of pa ents i.e. 51% belongs to age group of 6-10 years.Similar pa ern of age and gender distribu on was observed in a study of 15 Venkatesh KS et.al.In our study, gene Xpert detected 15 cases of tuberculosis which was 3 of cases found in smear microscopy for 16 AFB of sputum/gastric lavage.Pandey D et al. have also detected extra cases of tuberculosis by gene xpert which were not detected by smear microscopy.Our study showed 100% sensi vity and specificity for gene xpert of sputum/gastric lavage sample for AFB which is similar to the 14 findings of Das A etal. done at Ins tute of medical sciences, Varanasi, India and study done at in Beijing Children'sClinical features of pediatric pulmonary tuberculosis are non-specific and radiological findings also vary widely.Pediatric tuberculosis is pauci-bacillary in nature so; microscopy is usually nega ve even in posi ve pa ents.Although culture being gold standard is me taking and has got its own limita ons.In such cases, gene xpert is a diagnos c modality of choice to detect the cases rapidly.