Background Itraconazole and voriconazole are the drugs of choice for Lomentospora prolificans and Scedosporium apiospermum. Posaconazole, is often substituted when there is intolerance or lack of efficacy to first line agents. Terbinafine, an allylamine antifungal, is recommended with an azole for the treatment of L.prolificans, though there is no published use of this combination in children with cystic fibrosis (CF).

Aim To evaluate the safety, tolerability and efficacy of this regimen in CF children.

Methods Retrospective case note review of CF children receiving terbinafine and posaconazole, from Nov 2015 to Nov 2016. Children were identified from pharmacy records and clinical data collected from case notes and laboratory records.

Results There were 4 children (all girls), median age 15 years (range 10–16), with a median FEV1% predicted of 70.5% (range 55–88%). 2 children chronically isolated L.prolificans, 2 isolated S.apiospermum. 3 also had CF related diabetes and chronic Pseudomonas aeruginosa infection. 1 child received treatment for 6 weeks. 3 children are taking long- term treatment (median 50 weeks; range 35–59). 2 children improved FEV1% predicted with treatment by 14% and 15%; one was stable. Importantly the trend graphs for lung function in these 3 children appear to stabilise post initiation of treatment. One child did not improve her lung function but also had recurrent MRSA infections and significant nutritional complications. No adverse effects from the combination were reported. Posaconazole levels were therapeutic (>1 mg/l) in all children (range 1.22–3.85 mg/l). Terbinafine levels were not measured.

Conclusion In this small case series, combination treatment with posaconazole and terbinafine was well tolerated and a positive clinical effect on lung function was evident. This is the first report on the use of this regimen for this indication in CF children and we will continue to use it, whilst gathering safety and efficacy data.