Investigation The Antibiotic Resistance Of Acinetobacter Baumannii By Phenotypic Methods

Objectives :Acinetobacter baumannii is one of the most common pathogens in nosocomial infection.In recent years,the antibiotic resistance is become more and more widely,bring about a lot of problems for clinical treatment.Therefore,to understand the infection,antibiotic resistance and the mechanism of drug resistance,can provide a basis for the clinical treatment of the infection in a timely and effective manner.The mechanism of drug resistance is complex,the mainly mechanism was due to the production of CHDLs.In this experiment we isolated 121 strains non repeat Acinetobacter baumannii of from the patients administrated in the Third Hospital of Xingtai City and the Second Affiliated Hospital of Hebei Medical University since January,2014 to June,2015.Carbapenemases was detected by the phenotypic methods of CarbAcineto NP and CIM And compared with the gene detection to find a more sensitive and specific method to provide the experimental basis for the detection of the carbapenemases of Acinetobacter baumannii by phenotypic methods in the laboratory.Methods:Clinical specimens was collected from nosocomial infection patinets in the Third Hospital of Xingtai City and the Second Affiliated Hospital of Hebei Medical University since January 2014 to June.A total of 121 strains of Acinetobacter baumannii was isolated and identified by automatic microbial bio Merieux VITAK-2 compare for bacteria identification and drug sensitivity test,according to the Clinical Laboratory Standardization Committee(CLSI)2014 edition of the standard.The genomic DNA was extracted by boiling method,And the antibiotic resistance genes were detected by PCR.The CarbAcineto NP method and CIM method were used to detect the carbapenemases of 121 strains of Acinetobacter baumannii.The sensitivity and specificity of CarbAcineto NP and CIM methods were compared for the detection of the carbapenemasesResults:121 strains of Acinetobacter baumannii mainly isolated from the Intensive care unit and Department of neurosurgery and Department of Neurosurgery ICU,Department of respiration(74.4%).The main types of specimens were sputum(87.6%),Followed by cerebrospinal fluid,urine,secretions,pleural effusion and drainage.Among the 121 strains of Acinetobacter baumannii.70 strains were resistant to imipenem or meropenem,the resistant rate was 57.9%,Among them,67 strains were showed carrying OXA-23 gene,the gene carrying rate was 95.7%;no KPC,IMP and VIM genes were detected.Among the 69 strains of OXA-23 positive strains,60 strains were detected positive by CarbAcineto NP and 64 strains of were positive by CIM;in the 52 strains of OXA-23 negative strains,50 strains of were negative when detected by CarbAcineto NP,but 51 strains of were negative when detected by CIM;When compared with OXA-23 gene detection,the sensitivity and specificity of CarbAcineto NP were 86.9% and 96.2%,respectively.The sensitivity and specificity of CIM were 92.8% and 98.1%,respectively.When the results were analysised by chi square test,the distance between CarbAcineto NP and PCR and that between CIM and PC%R methods were not significant,P>0.05,and so was the difference between the CarbAcineto NP and CIM,P>0.05,Conclusion:In Intensive care unit and Department of neurosurgery and Department of Neurosurgery ICU,Department of respiration,Acinetobacter baumannii was the most common pathogen of the nosocomial infection.The antibiotic resistance of Acinetobacter baumannii is severe and widespread.Imipenem or meropenem,that were effective in the past years,were not as effective as they were,with a resistant rate as high as 57.9%.OXA-23 was the major genotype of the carbapenem-resistant Acinetobacter baumanii.By comparison of the results we got by CarbAcineto NP and CIM methods we found that the sensitivity and specificity of CIM were higher.Compared with CarbAcineto NP,CIM method is more simple in operation,and the cost lower.Furthermore,this method was shown to be unaffected by incubation temperature or time,disk manufacturer,laboratory staff and the age of the culture or bacterial suspension,that suggested this method was a highly cost-effective phenotypic screening method that could be used for the detection of carbapenemase in clinical.