Formation Mechanism And Antiphagocytic Effect Of Acinetobacter Baumanii Biofilm On Inner Wall Of Breathing Machine Catheter

ObjectiveTo explore the formation condition and process of Acinetobacter baumanniibiofilm and its anti-phagocytosic effect, and to provide theoretical basis for thecontrol of intractable nosocomial infection caused by Acinetobacterbaumannii.MethodsAcinetobacter baumannii on the inner wall of invasive catheter in newbornintensive care unit (NICU) were isolated and identified. Then the liquid flow inthe catheter was simulated for the formation of Acinetobacter baumannii. Themorphological structure of the biofilm was observed with electron microscope.Confocal laser scanning microscopy (CLSM) was used to observe thepolysaccharide on the surface of the biofilm. Anti-phagocytosic effect of biofilmwas examined with cell phagocytosis test.ResultsAcinetobacter baumannii was detected in the ventilator catheter ofrespirator for the newborns with severe disease in NICU. Acinetobacterbaumannii biofilm was reconstructed in vitro and extracellular polysaccharidesof the biofilm was observed with CLSM. The normal fimbriae and sex pili, aswell as the multiple bonding, on the surface of Acinetobacter baumannii in thebiofilm were identified with electron microscopy. The biofilm could inducechemotaxis and sorption of phagocytic cells, whereas the phagocytes could notengulf but wrapped up by the biofilm. ConclusionsThe formation of Acinetobacter baumannii biofilm correlates withnosocomial infection relevant to ventilator catheter used in NICU. The biofilmmay formed more likely in the presence of newly isolated clinical bacteriacompared to that of laboratory strains. The biofilm mainly consists of bacterialmass, cellulose-like substances, and cross-linked structure. The piliadhesion isthe basis of biofilm formation. The bacterial biofilm has a stronganti-phagocytosic effect, which may be one of important causes for recurrentepisodes of clinical infection.