Molecular epidemiology and its risk factors for efflux pump gene expression of multi-drug resistant pseudomonas aeruginosa isolated from ICU patients

Objective: The purpose of this study was to evaluate the molecular epidemiology and the risk factors for efflux pump gene expression of multi-drug resistant pseudomonas aeruginosa (MDRPA) isolated from ICU patients. Methods: Specimens were derived from sputum, blood, or wound secretions of 78 ward admitted patients diagnosed with MDRPA in the department of ICU of our hospital from January 2014 to June 2016. Polymerase chain reaction (PCR) and real-time PCR assays were used to detect the efflux pump gene (MexAB-OprM, MexCD-OprJ, MexEF-OprN) expression of MDRPA isolated from ICU patients. Results: The MexAB-OprM, MexCD-OprJ and MexEF-OprN positive expression rates of MDRPA were 100% (78/78), 35.9% (28/78) and 46.2% (36/78), respectively. The resistance rates to gentamicin, chloramphenicol and ampicillin/sulbactam were 100%. The resistance rates to levofloxacin and ciprofloxacin were > 90%. The resistance rates to cefoperazone, cefotaxime, cefoperazone/sulbactam and aztreonam were > 50%. Application of carbapenem antibiotics (OR = 5.17, P < 0.05), invasive medical procedure (OR = 5.32, P < 0.05), hypolekocytosis (OR = 4.80, P < 0.05), chronic diseases (OR = 2.55, P < 0.05) and cancer (OR = 5.54, P < 0.05) were associated with high MexAB-OprM gene expression. Application of carbapenem antibiotics (OR= 11.61, P < 0.05), application of macrolide antibiotics (OR = 3.57, P < 0.05), invasive medical procedure (OR = 12.50, P < 0.05) and hypolekocytosis (OR = 3.13, P < 0.05) were risk factors for positive MexCD-OprJ gene expression. Application of carbapenem antibiotics (OR = 4.67, P < 0.05), macrolide antibiotics (OR 9.92, P < 0.05), invasive medical procedure (OR = 8.17, P < 0.05) and hypolekocytosis (OR = 6.42, P < 0.05) were independent factors for positive MexEF-OprN gene expression. Conclusion: MDRPA strains isolated from the ICU ward of our hospital were severely resistant to antibiotics. The normalized use of carbapenems and glycopeptides antibiotics, the reduction of unnecessary invasive procedures and the severely grasped standard of hospitalized in ICU ward played important roles in the prevention of the overexpression of the efflux pump genes of MDRPA.