Management of Pulmonary Disease in Patients with Cystic Fibrosis

A randomised controlled trial of rosuvastatin for the prevention of aminoglycoside-induced kidney toxicity in children with cystic fibrosis

The PROteKT study tested the hypothesis that rosuvastatin can inhibit aminoglycoside-induced nephrotoxicity in children with Cystic Fibrosis (CF). This open label, parallel group, randomised controlled trial recruited children and young people aged 6 to 18 years with CF at 13 paediatric CF treatment centres in the UK. Participants were randomised equally to either receive oral rosuvastatin (10 mg once daily) or no intervention (control) throughout clinically indicated treatment with intravenous tobramycin. The primary outcome was the difference between the groups in mean fold-change in urinary Kidney Injury Molecule-1 (KIM-1). Fifty (rosuvastatin n = 23, control n = 27) participants were recruited between May 2015 and January 2017. Primary outcome data was available for 88% (rosuvastatin n = 20, control n = 24). The estimated mean treatment difference in the geometric mean-fold change of normalised KIM-1 was 1.08 (95% CI 0.87–1.35, p = 0.48). In total there were 12 adverse reactions, all mild, reported by five participants randomised to rosuvastatin, and one serious adverse event in each group. Whilst no protective effect of rosuvastatin was seen, there was a lower than expected level of nephrotoxicity in the cohort. Therefore, we can neither confirm nor refute the hypothesis that rosuvastatin protects against aminoglycoside nephrotoxicity.

Activity of pulmonary vancomycin exposures versus planktonic and biofilm isolates of methicillin-resistant Staphylococcus aureus from cystic fibrosis sputum

Vancomycin is commonly used to treat methicillin-resistant Staphylococcus aureus (MRSA) infections in patients with cystic fibrosis (CF) lung disease. However, there are limited data to support the in vitro activity of this agent against MRSA isolated from CF sputum. The primary objective of this study was to evaluate the activity of vancomycin at pulmonary concentrations (intravenous and inhaled) against four clinical MRSA CF sputum isolates in planktonic and biofilm time-kill (TK) experiments. Vancomycin minimum inhibitory concentrations (MICs) were determined for these isolates at standard inoculum (SI) (~10⁶ CFU/mL) and high inoculum (HI) (~10⁸ CFU/mL) as well as in biofilms cultivated using physiological medium representing the microenvironment of the CF lung. Vancomycin concentrations of 10, 25, 100 and 275 µg/mL were evaluated in TK experiments against planktonic MRSA at varying inocula and versus biofilm MRSA. Vancomycin MICs increased from 0.5 µg/mL when tested at SI to 8-16 µg/mL at HI. Vancomycin MICs were further increased to 16-32 µg/mL in biofilm studies. In TK experiments, vancomycin displayed bactericidal activity (≥3 log₁₀ killing at 24 h) against 1/4 and 0/4 planktonic MRSA isolates at SI and HI, respectively, whereas vancomycin was bactericidal against 0/4 isolates against MRSA biofilms. Based on these findings, vancomycin monotherapy appears unlikely to eradicate MRSA from the respiratory tract of patients with CF, even at high concentrations similar to those observed with inhaled therapy. Novel vancomycin formulations with enhanced biofilm penetration or combination therapy with other potentially synergistic agents should be explored.