ABSTRACT
Background: Infections by multidrug-resistant [MDR] and pan-resistant A.baumanii have become a challenging problem. Resistance to carbapenems is a rising problem. Tigecycline provided a new hope for the treatment of MDR- A. baumannii infections. Our aim was to assess the incidence of MDRA. baumanii in various nosocomial infections in our institution, detecting the carbapenemase activity in those strains and finally in vitro evaluation of tigecycline against sensitive and MDR-A.baumanii strains
Methods: A.baumanii strains were isolated from different nosocomial infections in Specialized Medical Hospital, identified by API 20E,antibiotic sensitivity by disc diffusion method was done. Carbapenemase activity was tested in IMP- resistant strains by Imipenem EDTA double disc synergy test[DDST], Modified Hodge test, and finally detecting metallo-beta lactamase gene blaIMP by PCR. In vitro susceptibility to tigycycline by broth microdilution test was done for all isolated A.baumanii strains
Results: Thirty MDR -A.baumanii strains were isolated which represents 8% of all nosocomial infections. The most significant associated risk factor was: previous antibiotic intake, presence in intensive care units [ICUs], mechanical ventilation, indwelling catheter, urinary catheter, and peripheral vascular disease. Carbapenemase activity was detected in 44.4% by DDST, in 33.3% by the Modified Hodge test and blaIMP gene was detected in 50% by PCR. The DDST had 89% sensitivity and 100% specificity. Tigecycline showed MIC50 value of 1mg/L and MIC90 of 2mg/L with a unimodal susceptibility in carbapenem sensitive and resistant strains
Conclusion: MDR-A.baumanii is an emerging problem in our institution. DDST and M.Hodge test can be used for screening of cabapenemase. Tigecycline had a good activity against the MDR A. baumannii strains while maintaining the same MIC90 of 2 mg/L against the carbapenem-resistant and sensitive strains