Mycobacterium abscessus complex (MABSC) is a rapidly growing mycobacterium and may rarely cause disseminated infections in immunocompromised patients. In patients with Cystic Fibrosis (CF), it peaks between the ages of 11 and 15 years. We present a 5 months old infant with coexisting CF and Progressive Familial Intrahepatic Cholestasis (PFIC) who had pulmonary and cutaneous dissemination of MABSC infection. The management of this disseminated infection in an infant with two coexisting chronic diseases was challenging which resulted in a rapid deterioration of lung disease and the progression of PFIC to liver cirrhosis with a fatal outcome. Keywords: Cystic Fibrosis; Atypical Mycobacterium; Mycobacterium abscessus complex; Progressive Familial Intrahepatic Cholestasis

Background: Cystic fibrosis (CF) is a multisystemic chronic disease caused by mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) protein. These mutations are classified in to six classes. Ivacaftor is a CFTR potentiator which partially restores the CFTR function for class III mutations. In Oman, p.Ser549Arg (class III) is the most common mutation (65% of cases). Our study prospectively evaluated the tolerance and clinical efficacy of ivacaftor. Methods: A prospective observational study was conducted at the Royal Hospital, Oman. All children aged 6–18 years who are followed and carry at least one copy of the p.Ser549Arg mutation were started on Ivacaftor and included in the study. Data collected included weight, height, forced expiratory volume in first second (FEV1), sweat chloride concentration, stool elastase level and liver enzymes at baseline and at 12, 24, 36, and 48 weeks after initiation of treatment. The number of CF pulmonary exacerbations one year before and during treatment were compared. Results: Twenty one children were started on Ivacaftor (90% homozygous for p.Ser549Arg). The mean age was 10.8 (SD ±3.5) years. When compared to baseline, FEV1 significantly improved by a mean of 10.8 (SD ±13.5) percentage points (pp) and 14.3 (SD ±7.5) pp at 12 and 48 weeks respectively. The sweat chloride level significantly dropped from a mean of 107 (SD ±8.5) mmol/l to 38.5 (SD ±22.3) mmol/l at 12 weeks and remained low. The Body Mass Index (BMI) improved by a mean of 1.37 (SD ±1.3) kg/m 2 and 1.9 (SD ±1.35) kg/m 2 at 24 and 48 weeks of treatment respectively. The number of admissions the year before and during treatment reduced significantly from a mean of 2.2 (SD± 1.9) to 0.7 (SD ±1) admission per year. Two children developed transaminitis. Conclusion: Ivacaftor is well tolerated and resulted in a significant improvement in FEV1, BMI and sweat chloride level in children with p.Ser549Arg CFTR mutation.

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5179 Introduction: Patients with β-thalassemia major receive regular blood transfusions. Non-invasive hemoglobin (Hb) estimation may simplify their care. Masimo Pronto-7 Pulse CO-oximetry device is used to non-invasively estimate the hemoglobin level but has not been previously validated in this group of patients. The primary objective of this study was to validate the pulse CO-oximetry based hemoglobin estimation in children and adults with thalassemia major. Methods: We conducted a prospective observational study on 108 children and adults with thalassemia major attending the daycare thalassemia center of a tertiary care hospital over 6 weeks. We estimated a spot Hemoglobin (Sp Hb) level using Masimo Pronto-7 Pulse CO-oximetry device (two measurements per patient) and compared it to a venous sample Hb (Reference Hemoglobin; Ref Hb) measured using Abbott CELL-DYN Sapphire hematology analyzer. We calculated Pearson correlation coefficient and coefficient of determination (R2). The multivariable linear regression model of predicting the estimation differences included age, gender, weight, height, blood pressure and reference hemoglobin. Results: We enrolled 108 patients (54 males, 54 females) with a mean age of 21. 6 years (SD 7. 3; 2. 5–38). There were 156 estimation episodes. The mean Ref Hb and SpHb were 9. 4 g/dL (SD 0. 9; 7. 1–12. 3) and 11. 1 g/dL (SD 1. 2; 7. 5–14. 7) respectively. The correlation coefficient between the Sp Hb and Ref Hb was 0. 49 (R2 = 24%) with a mean difference of 1. 7 g/dL (SD 1. 1; −1. 2 to 4. 3). In the multivariable model, Ref Hb level was the only statistically significant predictor of the difference in measurement (p =0. 002). There was a strong correlation between the two CO-oximetry Hb measurements (correlation coefficient 0. 70, R2 = 50%). Conclusions: Our results indicate that Masimo Pronto-7 Pulse CO-oximetry device overestimates the hemoglobin level and it cannot be recommended for patients with thalassemia major. Larger prospective studies are needed to confirm these results. Disclosures: No relevant conflicts of interest to declare.