Analysis of the Resistance in Acinetobacter Baumannii to Common Antibiotics / 医学研究杂志

ABSTRACT

Objective To study the mechanism of the resistance in Acinetobacter baumannii to common antibiotics.Methods Bacterial susceptibility test to ?-lactamatic antibiotics,quinolones,aminogiycosids were done by the Kirby-Bauer method and agar dilution method for 35 isolates.Penicillin-beta-lactamase,AmpCs,Metallo-beta-lactamase,ESBLs were detected by iodine-starch test,3-dimension test,microbiology sensitivity synergic test,disc agar diffusion method respectively.Outer membrane protein was analyzed by SDS-PAGE.Accumulation of ciprofloxacin was determined by direct Fluorescence method.The gene of Tem-1,aac-4 and gyrA were amplified by PCR while the gyrA was sequenced.Results 28 isolates were multi-resistant to common antibiotics in 35 isolates.16 isolates produced Penicillinase,10 isolates produced Cephalosporinase,2 isolates produced metal-beta-lactamase,3 isolates produced ESBLs.The analysis of outer membrane proteins showed that a protein of 29kD disappeared and 26kD protein enhanced in resistant isolates.The accumulation of ciprofloxacin in resistant isolates decreased.After treatment with NaN_3,the drug uptake increased to the normal level.Most of [QX(Y8]Tem-1 gene were positive except 2 drug resistant and 3 sensitive isolates.All of [QX(Y8]aac-4 were negative while gyrA were positive.DNA sequencing analysis revealed there had point mutation in the gyrA gene.Conclusion Beta-lactamase,active drug efflux,outer membrane protein permeability decreasement and gene mutation were the factors contributing to the antibiotics resistance of Abaumannii.