The role of secretory immunoglobulin A, neutrophils and pathogens in the early onset-ventilator acquired pneumonia, based on analysis of bronchoalveolar lavage specimen

Background and Aim: Early-onset VAP cause high morbidity/mortality, longer/higher cost of treatment. Secretory-IgA and neutrophils play important role in earlyonset VAP. Exploration the role of these components in local immunity of respiratory system, has been done toward concentration of s-IgA, percentage of neutrophil and kind of pathogens of BAL specimen in mechanical ventilator - patients > 48 hours. Methods: Cohort study of s-IgA levels, percentage of neutrophil and pathogensof BA specimen, in mechanical ventilator-patients.Sampling was carried out, on 1^st and 3^rd dayof using mechanical ventilator. On the 3^rd day, subjects were divided into 2 groups: VAP(-) group:28 persons;and VAP(+)group: 33 persons.VAP (+), if scores of CPIS (Clinical Pulmonary Infection Score)>6. Results: In early-onset VAP patients, the level of s-IgA has increased significantly andcan reduce theneutrophils. The kind of pathogens play important role in stimulatingor destroying s-IgA, and contribute significantly to the VAP incidence, whereas percentage of neutrophil increased in all of pathogens infections. InVAP(-)MRSAinfection group, s-IgA level decreased belowthe baseline and percentage of neutrophil increased non-significantly and was controlled.In VAP(+) group,percentage ofneutrophil increased significantly and play important role in the incidence and deterioration of VAP.In this study, the four highestpathogensin mechanical ventilator - patientsare A. baumannii (42,31%), MRSA (21,79%), K. pneumonia (12,82%) and P. aeruginosa (8,97%). Conclusion: S-IgA and neutrophilscooperate each otherin local immunity mechanism,and s- IgA can suppress excessive reaction of neutrophils.S-IgAgive different responses to pathogens pattern and can destroyed by certain pathogen, while neutrophils do not give different response to different pathogens and give contribution in worsening the incidence of VAP.The most kind of pathogensin mechanical ventilator-patientsare A. baumanii, MRSA, K. pneumonia andP. Aeruginosa.