In vitro activity of tigecycline and minocycline against multidrug-resistant and pandrug-resistant Acinetobacter baumannii

OBJECTIVE To evaluate the in vitro activity of tigecycline and minocycline against multidrug-resistant Acinetobacter baumannii(MDRAB) and pandrug-resistant A.baumannii(PDRAB) through detecting MICs of these two drugs against MDRAB and PDRAB,so as to instruct the clinical medication.METHODS A total of 60 MDRAB isolates and 67 PDRAB isolates were collected from Jul,2010 to Jun,2011.E-test method was employed to detect the in vitro activity of tigecycline and minocycline and their MIC values.RESULTS The susceptibility rates of 127 strains of ABA to tigecycline and minocycline were 40.9% and 30.7%,respectively,and the intermediate rate to tigecycline was 14.2%,slightly higher than 7.1% of minocycline;the susceptibility rates of 60 MDRAB isolates to tigecycline and minocycline were 51.7% and 41.7%;the MIC50 values of the two antibiotics were 2 μg/ml and 8 μg/ml,respectively,MIC90 values were 16 μg/ml and 64 μg/ml;among the 31 strains of cefperazone/sulbatam-resistant ABA isolates,the susceptibility rates to tigecycline and minocycline were 35.5% and 29.0%,and the MIC50 values of tigecycline and minocycline were 4 μg/ml and 24 μg/ml,while the MIC90 values were 32 μg/ml and 96 μg/ml,respectively;the susceptibility rates of 67 PDRAB isolates to tigecycline and minocycline were 31.3% and 20.9%,the MIC50 values were 8 μg/ml and 32 μg/ml,and the MIC90 values were 48 μg/ml and 96 μg/ml,respectively.CONCLUSION The in vitro activity of tigecycline against MDRAB and PDRAB is a little higher than that of minocycline,the susceptibility rates to both antibiotics are not so high in this region,and this phenomenon deserves our attention.