Surfactants의 Hemophillus influenzae 증식억제에 대한 Nitric Oxide의 영향

Abstract

Pulmonary surfactant has been shown to play an important role in bacterial clearance at the alveolar surface in the lung as well as in contributing to lung mechanics. The antimicrobial activity of the surfactant against a number of bacterial species was reported. Surfactant replacement is a potential life saving therapy in respiratory distress syndrome. The most striking acute effect has been obtained with modified natural surfactant preparations containing both surface active lipids and proteins SP-B and -C. The clinical application of artificial surfactants has been steadily increased. Otherwise, inhalation of nitric oxide(NO) is applied for treatment on the respiratory distress syndrome. NO is also synthesized in many different cell. Macrophage-derived NO has a role in antimicrobial defense. Surfactant and inhaled NO are often used simultaneously in the treatment for the respiratory distress syndrome. But, NO2, which is oxidized from air NO, has toxic effects on the surfactant system. So, there is need to understand the possible interactions between NO and the surfactant. Especially, antimicrobial effects of surfactant by NO has not been studied in depth. H. influenzae is quite common pathogen in neonatal sepsis. In the respiratory distress syndrome, 5-10 % of patients were infected with pneumonic bacteria. Especially, clinical characteristics of the infection with H. influenzae were similar to those of early onset group B streptococcus including those respiratory distress syndrome. This study was performed to examine closely the effect of NO on the antimicrobial activity of surfactant. In this study, the effects of artificial surfactant on the growth of H. influenzae was investigated. The antimicrobial action of NO against loge was examined. And the effect of NO on antimicrobial activity of surfactant was also examined. Exponential growing H. influenzae was mixed with different concentrations of surfactants. Mixed solutions of bacteria-surfactant were incubated at 37℃ for 90 min. Then, the mixtures was serially diluted with physiological saline. Each dilution of mixture was streak-cultured on chocolate agar medium. And the number of viable bacteria was determined by colony counting after 18 hour incubation. By the same methods effect of NO on antimicrobial activity of surfactant was examined. The antimicrobial activity of NO were measured by spectrophotometer. Different concentration of SNAP(5-nitroso-N-acetyl-D, L-penicillamine) were mixed with bacterial cultured broth. After 3, 6, 10, 18 hour cultivation, the turbidity of bacterial was measured. Artificial surfactant(Exosurf and Surfactant-TA) almost completely inhibited the growth of H. influenzae at the concentration of 100%. There is no apparent difference between the treatments of two surfactants in the growth suppression of the tested microorganism. NO inhibited the growth of H. influenzae. NO affected the antimicrobial activity of artificial surfactants tested. This study suggested that NO inhibited the antimicrobial activities of artificial surfactants.