The Nosocomial Infection Characteristics And Gene Homologous Analysis Of Multi-drug Resistant Acinetobacter Baumannii In Xi'an

Objective:1. To understand the status of nosocomial infection of multi-drug resistant acinetobacter baumannii in the intensive care units(ICU) of 3 tertiary first-class hospitals in Xi 'an area, and to analyze the clinical characteristics and risk factors of hospital infection.2. To explore the spread mode and molecular mechanism through gene homology analysis of multi-drug resistant acinetobacter baumannii infection occurred in hospital.Methods:1. The multi-drug resistant acinetobacter baumannii strains were collected from the patients in ICUs in 3 tertiary first-class hospitals from June 2014 to February 2015.2. The antimicrobial resistance to 10 commonly used antibiotics in clinic was tested by MIC method.3. Case-control study was designed for analyzing risk fators, 71 patients with hospital infection of multi-drug resistant acinetobacter baumannii were as case group, and 73 without hospital infection were randomly selected as control group who had same admission time and lived same hospital with case group. The clinical and epidemiological information were collected, which included demographic information, invasive operation,antimicrobial agents use, mechanical ventilation use, and other possible related factors.4. The graph clustering analysis for multi-drug resistant acinetobacter baumannii genes was used of the pulsed field gel electrophoresis(PFGE) method, when the gene homology between two strains is 85% or higher as the same clone.Results:1. There were 5789 hospitalized patients in 7 ICUs in 3 hospitals, and total hospital stay were 47305 days. Of them, 475 cases occurred of hospital infection, and the infection rate was 8.21%, in which 71 cases were conformed belong to the multi-drug resistant acinetobacter baumannii, and its infection rate was 1.23%, and the thousand days infection rate of multi-drug resistant acinetobacter baumannii was 1.50‰. The sputum had the highest detection rate in all specimens with multi-drug resistant acinetobacter baumannii,and it was 76.11%; the infection site was mainly located on low respiratory tract, and it was accounted for 76.10%; and the comprehensive ICU had higher infection rate compared with other departments.2. All of multi-drug resistant acinetobacter baumannii were sensitive to Tigecycline,in addition to the Minocycline, and resistanc to other 8 kinds of clinical commonly used drugs was 74% or more, and resistance rate to Carbapenems was 100%.3. Through multi-factor Logistic regression analysis, we founded that 5 ICUs multi-drug resistant independent risk factors for nosocomial infection, which included antibacterial drugs combination use(OR=22.24), admission time in ICU(OR=16.17),Carbapenems use(OR=30.16), over 1 week lived same ward with multiple-drug resistant acinetobacter baumannii infection patients(OR=5.89), and mechanical ventilation use(OR=23.38)(P<0.05).4. We got 36 PFGE belts from 71 bacteria strains. Through the PFGE classification and clustering analysis, type A was main spread cloning(54.93%), while A2 subtype was dominant(49.30%), which was a major epidemic type in those 3 hospitals. A2 type of cloning strain was epidemic since June 2014 to February 2015. In addition, C clone,isolated from the Xijing hospital in July 2014, was also found in the first hospital of Jiaotong University in January 2015.Conclusions:1. The thousand days hospital infection rate of multi-drug resistant acinetobacter baumannii in ICU was 1.50‰ in Xi 'an region,and its positive rate in sputum specimen was the highest, comprehensive ICU had a higher incidence, which often occurred in low respiratory tract.2. We Should establish classification management system and drug resistance monitoring system for clinical antibacterial drug use, to guide reasonably, standardizing and effective use of antimicrobials, and to prevent the emergence and spread of drug-resistant bacteria.3. Multiple-drug resistant acinetobacter baumannii infection Carbapenems use before hospital infection, antibacterial drugs combination use, mechanical ventilation use,ICU admission days and the time lived in the seme ICU roomare independent risk factors for nosocomial infection of multi-drug resistant acinetobacter baumannii.4. The multi-drug resistant acinetobacter baumannii was a cloned transmission in different hospitals, and A2 subtype was the main cloning strain in those ICUs during the survey period, which suggests there may exist an intercross transmission phenomenon in those hospitals.