RESUMEN
Long-term administration of certain macrolides is efficacious in patients with persistent pulmonary Pseudomonas aeruginosa infection, despite how limited the clinically achievable concentrations are, being far below their MICs. An increase in the sub-MIC of macrolide exposure-dependent sensitivity to nitrosative stress is a typical characteristic of P. aeruginosa. However, a few P. aeruginosa clinical isolates do not respond to sub-MIC of macrolide treatment. Therefore, we examined the effects of sub-MIC of erythromycin (EM) on the sensitivity to nitrosative stress together with an efflux pump inhibitor (EPI) phenylalanine arginyl ß-naphthylamide (PAßN). The sensitivity to nitrosative stress increased, suggesting that the efflux pump was involved in inhibiting the sub-MIC of macrolide effect. Analysis using efflux pump-mutant P. aeruginosa revealed that MexAB-OprM, MexXY-OprM, and MexCD-OprJ are factors in reducing the sub-MIC of macrolide effect. Since macrolides interfere with quorum sensing (QS), we demonstrated that the QS-interfering agent furanone C-30 (C-30) producing greater sensitivity to nitric oxide (NO) stress than EM. The effect of C-30 was decreased by overproduction of MexAB-OprM. To investigate whether the increase in the QS-interfering agent exposure-dependent sensitivity to nitrosative stress is characteristic of P. aeruginosa clinical isolates, we examined the viability of P. aeruginosa treated with NO. Although treatment with EM could reduce cell viability, a high variability in EM effects was observed. Conversely, C-30 was highly effective at reducing cell viability. Treatment with both C-30 and PAßN was sufficiently effective against the remaining isolates. Therefore, the combination of a QS-interfering agent and an EPI could be effective in treating P. aeruginosa infections.
Asunto(s)
Antibacterianos , Eritromicina , Furanos , Proteínas de Transporte de Membrana , Pruebas de Sensibilidad Microbiana , Estrés Nitrosativo , Pseudomonas aeruginosa , Percepción de Quorum , Pseudomonas aeruginosa/efectos de los fármacos , Pseudomonas aeruginosa/genética , Pseudomonas aeruginosa/metabolismo , Pseudomonas aeruginosa/fisiología , Percepción de Quorum/efectos de los fármacos , Antibacterianos/farmacología , Estrés Nitrosativo/efectos de los fármacos , Eritromicina/farmacología , Proteínas de Transporte de Membrana/metabolismo , Proteínas de Transporte de Membrana/genética , Furanos/farmacología , Dipéptidos/farmacología , Macrólidos/farmacología , Infecciones por Pseudomonas/microbiología , Infecciones por Pseudomonas/tratamiento farmacológico , Humanos , Proteínas de la Membrana Bacteriana Externa/metabolismo , Proteínas de la Membrana Bacteriana Externa/genética , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/genéticaRESUMEN
Sub-MICs of the 14-membered macrolides erythromycin (EM) and clarithromycin (CAM) decreased the growth of Pseudomonas aeruginosa PAO1 and increased its sensitivity to endogenous and exogenous nitrosative stress. However, a 16-membered macrolide, josamycin (JM), was not or less effective. In 9 of 13 non-multidrug-resistant P. aeruginosa (non-MDRP) and 9 of 27 MDRP ST235 strains, the sub-MIC of EM induced significant reductions in bacterial numbers following treatment with a nitric oxide donor.