Invitro assessment ofcombined antibiotic andmucolytic treatmentfor Pseudomonas aeruginosa infection incystic fibrosis

SUMMARYTheminimal inhibitory concentration of azlocillin forPseudomonas aeruginosa isappreciably reduced whencombined withthemucolytic agent mesna(Mistabron) because ofan independent bacteriostatic effect ofmesna.Bactericidal activity ofazlocillin isunaltered bymesna. Mesnainhalations aloneorcombined withazlocillin may benefit cystic fibrosis patients withpseudomonas lung infections. Sodium 2-mercaptoethanesulphonate, mesna(Mistabron) isamucolytic agent showntohaveabeneficial therapeutic effect whengivenasanintermittent inhalation inselected patients withcystic fibrosis (CF).1 Manyofthesepatients havechronic lung infections withPseudomonas aeruginosa andrecent workbyHodsonetal.suggested thattheybenefit fromlongterminhaled antibiotics.2 Anearlier report examined theinteraction between N-acetylcysteine (NAC), another mucolytic agent, andthepenicillin groupofantibiotics. Itsuggested that NAC reduced theantibacterial effect ofthepenicillins andwarned against their combined use.3 4A morerecent study, however, showed that1% NACactually potentiated theantipseudomonal activity ofcarbenicillin in vitro.5 Wemeasured theantipseudomonal activity of azlocillin whencombined withmesnaanddeterminedifmesnaalonehadanyantipseudomonal activity.