| Objective:To learn out the antibiotics resistant characteristics of Acinetobacter baumannii isolates from Intensive Care Unit (ICU) in Qingdao region and detect the distribution of β-lactam resistance genes and aminoglycoside-modifying enzyme genes in multidrug resistant Acinetobacter baumannii, so as to provide experimental basis to guide the clinical application of antimicrobial agents.Methods:. From September2009to September2010,60non-duplicated clinical isolates of Acinetobacter baumannii were collected from three tertiary hospitals in Qingdao. All strains were identified by VITEK-2; K-B method was used to do drug susceptibility test; PCR was applied to detect8types of β-lactam resistant genes (TEM, CTX-M-1, DHA, SHV, OprD2, GES, OXA and VIM) and4types of aminoglycoside-modifying enzyme genes aac(3)-Ⅰ, aac(3)-Ⅱ, aac(6’)-Ⅰ and aac(6’)-Ⅱ.Results:①The specimens were mainly isolated from respiratory tract secretion, accounting for81.67%(49/60).②Among the60isolates collected, all showed100%resistance to Penicillin, furans and sulfa drugs; the resistance rate to Monocyclic beta-lactam drugs was98.33%; the resistance rate to Cephalosporin drugs:Cefazolin, Cefuroxime, Cefotaxime, Ceftazidime, eftriaxone, Cefepime was96.67%,93.33%,91.67%,86.67%,83.33%and75.00%, respectively; the resistance rate to β-lactam/β-lactamase inhibitor complexes such as Ampicillin/Sulbactam, Ticarcillin/clavulanicacid, Piperacillin/tazobactam, Cefoperazone/sulbactam was90.00%,85.00%,71.67%and45.00%; the resistance rate to carbapenem antibiotics such as imipenem, meropenem was35.00%,38.33%; the resistant rates to aminoglycoside antibiotics such as Gentamicin, Todramycin, Amikacin was95.00%,91.67%,73.33%; the resistance rate to quinolone drug such as Ciprofloxacin, Levofloxacin was93.33%,3.33%; the sensitive rate to Polymyxin B was100%.③The detection rate of multi-drug resistant A.baumannii and Pan-drug resistant A.baumannii was60.00%(36/60) and16.67%(10/60). The resistant rates to13of24drugs were100%in MDRAB, while the sensitive rates to Cefoperazone/sulbactam, imipenem, meropenem, Polymyxin B were higher, which was47.22%,55.56%,52.78%and100%, respectively. The difference of the resistance rates to13antibiotics between MDR strains and non-MDR strains were statistically significant (P<0.05).④Among the36mult-resistant strains, the toltal positive rate of β-lactamases genes was30.56%(11/36), The positive rates of TEM, CTX, GES, OXA, VIM were13.89%,5.56%,5.56%,11.11%and2.78%;4strains were lack of outer membrane channel protein oprD2gene, the loss rate of which is11.11%; The toltal positive rate of AMEs genes was61.1%(22/36), the positive rates of aac(3)-Ⅰ, aac(3)-Ⅱ, aac(6’)-Ⅰ were30.55%,33.33%,41.67%, respectively; DHA, SHV and aac(6)-Ⅱ genes were not found.Conclusions:①The infection caused by A.baumannii in ICU is mainly the respiratory system in this region ICU.②the resistance of A.baumannii in ICU is serious in this region, especially multi-drug-resistant A.baumannii, which were nearly no-sensitive to most of the antimicrobials commonly used in clinical. At present carbapenems (imipenem, meropenem) and inhibitors of β-lactamase (cefoperazone/sulbactam) were the first choice to the treatment of infection caused by Acinetobacter baumannii; If conditions permit, Polymyxin can be selected to treat infections, but the patient’s kidney function must be closely monitored.③The gene existence of (3-lactamases and (3-lactamases producing is one of the main resistance mechanism of Acinetobacter baumannii to β-lactam antibiotics. TEM and OXA were the major genotypes in this region. Some strains carrying two types of (3-lactamase genes involved in formation of bacterial drug resistance.④The toltal positive rate of AMEs genes is very high, indicating the gene existence of aac(3)-Ⅰ, aac(3)-Ⅱ, aac(6’)-Ⅰ are the main resistance mechanism of A.baumannii to aminoglycoside antibiotics in this region. |
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