INH Monoresistance tuberculosis with inhA gene resistance - What should be the anti-tuberculosis regimen?
Vaidehi Mehta1, Ira Shah2
1Pediatric TB Clinic, Department of Pediatric Infectious Diseases, B J Wadia Hospital for Children, Mumbai, India, 2Pediatric TB Clinic, Department of Pediatric Infectious Diseases, B J Wadia Hospital for Children,, Mumbai, India
Address for Correspondence: Vaidehi Mehta, 803-804 Natraj Society near Prabhodhan Thakrey hall sodawala lane Borivali (West),400092,Mumbai, India. Email: vaidehi.mehta2211@gmail.com
Keywords: INH Monoresistance, inhA gene resistance, Disseminated tuberculosis
Clinical Problem:
A 4-year-old boy presented with gradually increasing left axillary swelling for 7 months. There is no fever, cough, loss of appetite or weight loss or contact with a patient having tuberculosis (TB) contact. He had received immunization as per Universal Immunization programme (UIP) schedule including BCG at birth. On examination, weight was 15.5 kg (between 3rd- 50th centile as per World Health Organisation (WHO) growth charts) and height was 97 cm (between 3rd- 50th centile as per WHO growth charts ). There was a left axillary non-tender, matted and mobile swelling. Systemic examination was normal. Hemogram showed haemoglobin of 9.5 gm/dL, total leucocyte count of 13690/cumm (61% neutrophils and 30% of lymphocytes) and platelets 644 x 10^3/ul. Erythrocyte sedimentation rate (ESR) was 134 mm/hr. Chest Xray showed right upper and middle zone consolidation. Ultrasound (USG) of the swelling and abdomen showed small hypoechoic node in bilateral axilla, measuring 8 x 6 mm and 9 x 3 mm, central echogenic hilum maintained. HRCT chest showed subsegmental consolidation in anterior segment of right upper lobe with air bronchogram, multifoci of intraparenchymal coarse calcification within consolidation. Ill defined- multiple conglomerated mediastinal lymph node present. Right hilar lymphadenopathy was seen causing narrowing of middle lobe bronchus and multiple enlarged lymph node in left axilla. An excision of the axillary node was done that showed mycobacterium tuberculosis (MTB) with no rifampicin resistance on Xpert MTB/Rif assay. Histopathology of the node showed chronic granulomatous lymphadenitis extending upto subcutaneous tissue compatible with TB. Child was started on first line anti-tubercular therapy (ATT) comprising of Isoniazid (INH), Rifampicin (RIF), Pyrazinamide and Ethambutol. On follow up with Line Probe Assay (LPA) report showed resistance to inhA gene and sensitive to rpob and KatG gene and 6 week MGIT showed growth of MTB. Child was diagnosed as disseminated tuberculosis with INH monoresistance with inhA gene resistance and KatG gene susceptible.