Research On AdeABC Efflux Pump Of Acinetobacter Baumannii And Analysis Of Risk Factors On Prognosis Of Acinetobacter Baumannii Bloodstream Infection

Objective To study the sensitivity of Acinetobacter baumannii clinically isolated from the inpatients in the General Hospital of Tianjin Medical University on various kinds of antibiotics, understand the relationship between its efflux pump Ade ABC expression and the resistance as well as expression regulation, discuss the factors influencing its bloodstream infections prognostic risks, and guide clinically effective control the spread of drug-resistant strains within the hospital.Methods A retrospective investigation is made on non-repeatable Acinetobacter baumannii clinically isolated from January 2011 to December 2013 from the aseptic body fluids of the inpatients in one top three hospital in Tianjin; the statistics is conducted on the department distribution and drug resistance characteristic. 33 strains of acinetobacter baumannii and 5 strains of sensitive plant of multidrug resistance non-repeatable Acinetobacter baumannii clinically isolated from 2011 to 2014 from the inpatients in General Hospital of Tianjin Medical University are collected; the repeated strains isolated from the same patient and the same part are removed.Bacteria identification and drug sensitive test are carried out by using Vitek-2compact system and supporting susceptibility card; the susceptibility of cefoperazone/Sulbactam is tested by disk diffusion method(K-B). RT-PCR is applied to detect ade B expression level; PCR is applied to detect ade B and regulatory gene ade RS. Retrospective analysis is made on 80 cases of inpatients with acinetobacter baumannii bloodstream infections in General Hospital of Tianjin Medical University between January 2011 and May 2011. According to 28 days’ prognosis, they are divided into death group(56 cases) and survival group(24 cases), including age,gender, admission department, basic diseases, treatment, invasive operation, bacterial drug resistance and acute physiology on admission,as well as scores of chronic health conditions scoring system II(APACHE II); the related factors influencing the prognosis are analyzed with multiple logistic regression.Results(1) A total of 49, 59 and 81 strains of acinetobacter baumannii were obtained respectively in 2011, 2012 and 2013; all of them were common in the intensive care units, 30, 38 and 56 strains of multi-drug resistant acinetobacter baumannii weredetected respectively in 2011, 2012 and 2013; they had higher resistance to clinically commonly-used antibiotics and were the most sensitive to Tigecycline.(2) The PCR detection results show that ade B exists in resistant strains and sensitive strains and ade RS exists in resistant strains. 8 strains of multi-drug resistant strains are selected to conduct RT-PCR and the results shows they are significantly high expression.(3)The resistance rate of 80 strains of acinetobacter baumannii to ceftazidime,ceftriaxone and cefoxitin is above 90%; their resistance rate to imipenem is 66.2%;and their resistance rate to cefoperazone/sulbactam as well as tigecycline is as low as7.5% and 2.5% respectively. ICU admission [Odds ratio(OR)=6.67; 95% confidence interval(95% CI) is 2.01~22.07; P=0.002], multi-drug resistance(OR= 3.55; 95% CI is 1.30 ~9.69; P=0.014), APACHE II(OR=39.00; 95% CI is 9.87~154.09; P=0.000),arterial catheterization(OR=3.24; 95% CI is 1.16~9.04; P=0.025), central venous catheter(OR= 3.33; 95% CI is 1.22~ 9.12; P= 0.019), tracheal intubation(OR=3.60,95% CI is 1.31~9.88; P=0.013), tracheotomy(OR=3.21; 95% CI is 1.19~8.66;P=0.021), and other invasive operation(OR=3.00; 95% CI is 1.11~8.08; P=0.030) are the risk factors of the death of patients with acinetobacter baumannii bloodstream infections.Conclusion The infection rates of acinetobacter baumannii are rising constantly;especially for immunocompromised patients, the resistance and multi-drug resistance of acinetobacter baumannii islocated from sterile body fluid are more serious, thus,great importance should be attached to it clinically. Ade S and ade R may regulate the expression of ade B and play an important role in the process of mediating multi-drug resistance. The ade B expression index in multi-drug resistant acinetobacter baumannii is high expression and shows that the expression of efflux pump is an important cause of its multi-drug resistance. Besides, invasive operation and drug resistance of bacteria can increase the case fatality rate of acinetobacter baumannii bloodstream infection.