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KMID : 0377519950200040359
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Chung-Ang Journal of Medicine
1995 Volume.20 No. 4 p.359 ~ p.368
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Effect of Surfactant on Streptococcus pneumoniae and Neisseria meningitidis Growth
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Chung Sang-In
Moon Eon-Soo
Kim Ki-Jeong
Kim Min-Hee
Choi Chul-Soon
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Abstract
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Pulmonary surfactant is a surface-active material lining the alveolar of the lung and a lipid-protein complex consisted of about 90% lipids and 5~10% surfactant-specific proteins. Pulmonary surafctant 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 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. However their effect on the bacteria has not been widely studied. The mechanism of damage on bacteria treated with surfactants has not been clarified. S. pneumoniae, H. influenzae and N. meningitidis are quite common pathogens 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 by early onset group B streptococcus including those respiratory distress syndrome. Surfactant has been reported to be bactericidal for group B streptococcus. The phenomenon of surfactant inactivation is caused by adult respiratory distress syndrome, neonatal respiratory distress syndrome and meconium aspiration syndrome. One aspect of meconium aspiration syndrome is severe respiratory distress syndrome characterized by hypoxia, intrapulmonary shunting, and decreased lung compliance. The precise mechanism of surfactant inactivation by meconium is unknown. However biophysical inactivation of surfactant by meconium has been reported. Antimicrobial effects of surfactant by meconium has not been studied in depth. The purpose of this study was to investigate effects of artificial surfactant on the growth of S. pneumoniae and N. meningitidis. Exponential growing S. pneumoniae and N. meningitidis were mixed with differentiated concentration of surfactants. Mixed solutions of bacteria-surfactant were incubated at 37℃ during 90 min. Then, the mixtures was serially diluted with physiological saline. Each dilution of mixture was streak-cultutred on chocolate agar medium. And the number of viable bacteria was determined by colony counting after 18 hour incubation. The mixture of bacteria-surfactants was processed for transmission electronmicroscopic observation. Artificial surfactant(Exosurf and Surfactant-TA) almost completely inhibited the growth of S. pneumoniae and N. meningitidis at the concentration of 100%. The growth of S. pneumoniae was also inhibited at 10% concentration. There is no apparent difference between treatment of two surfactants in the growth suppression of the tested organisms. surfactants resulted in the damage of S. pneumoniae and N. meningitidis. And the damages were characterized by distortion of cell membrane and bleb formation. This study suggested that artificial surfactants would reduce the severity of bacterial pneumonia in hyaline membrane disease and meconium aspiration syndrome with bacterial infection.
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KEYWORD
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surfactants, antimicrobial effect, S. pneumoniae, N. meningitidis
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