The Study Of Risk Factors And Nosetiology Of Ventilator Associated Pneumonia

Objective:The current study was designed to investigate the risk factors and nosetiology of ventilator associated pneumonia(VAP) in ICU of Shaanxi Provincial People's Hospital.Methods:One hundred and eight patients receiving mechanical ventilation in ICU of Shaanxi Provincial People's Hospital were enrolled in the study.After establishment of artificial airway,the secretion samples of respiratory tract from all patients were collected with sterile suction tube or bronchoscope,and processed for bacterial culture and drug sensitivity analysis immediately.The selection criteria were squamous cell＜10/LP and white blood cell＞25/LP.Then the sample was inoculated into blood agar plate,MacConkey plate and chocolate plates.The plates were put into homoeothermic incubator and CO₂ incubator and incubated at 37℃for 18～24h. Bacterial identification and susceptibility were analysed by automatic bacteria tester according to the standard criteria established by United States National Committee for Clinical Laboratory Standard in 1999.The Drug sensitivity test was carried out by disc diffusion method.The isolated strains were identified.Gram-positive cocci were identified through biochemical reaction,and Gram-negative bacilli were identified with gene code.All suspected bacteria were identified according the methods provided by Bergey's manual of Systematic Bacteriology.Additionally,the suspected anaerobic bacteria were tested by anaerobic culture procedure.The Staphylococcus aureus(ATCC 25923),Escherichia coli(ATCC 25922) and Pseudomonas aeruginosa (ATCC 27853) were used as control strains(all provided by Center for Clinical Laboratory of Ministry of Health).Results:1) The incidence rate of VAP was higher in the elder patients(P＜0.05).2) Patient with severe chronic diseases such as chronic lung disease had higher VAP incidence(P＜0.05).3) The ventilation time was a significant risk factor for VAP patients(.P＜0.05).4) Patients receiving tracheostomy tube got higher VAP incidence when compared with patients receiving oral nasal intubation(P＜0.05).5) The use of acid-suppressing agents was not related with VAP incidence.6) The incidence of VAP in the group with abuse of antibiotics was significantly higher(P＜0.001).7) The acquired pathogenic bacteria from all VAP patients' specimens in this study were Pseudomonas aeruginosa,Escherichia coli,Staphylococcus aureus,Candida albicans, Acinetobacter Bauman,Klebsiella pneumoniae,Staphylococcus epidermidis, Streptococcus pneumoniae,yeast-like fungus,Oidium tropioale,Haemophilus influenzae,Enterobacter cloacae,Enterobacter agglomerans and Aspergillus.Theses strains were highly resistant to ampicillin,cefazollin,piperacillin and ceftriaxone.The strains were also resistant to gentamicin,amikacin,ciprofloxacin,ceftazidime,and fewer were resistant to imipenem.The results of Gram-positive cocci susceptibility test showed Staphrlococcus aureus was resistant to a wide range of antibiotic,except for vancomycin.Conclusions:1) The occurrence rate of VAP was related with age,basic disease, duration of MV,intubation methods and antibiotics usage strategies.2) The pathogenic bacteria and spectrum for VAP in the current study had some variances compared with other reports.Gram-positive cocci and acinetobacter infection rate was high,while gram-negative infection was low.