| Acinetobacter baumannii（AB）is a conditioned pathogen.Due to the overuse of antibiotics,the constant mutation of bacteria and the lag in the development of new antibiotics,The number of effective drugs available for Multidrug-resistant Acinetobacter baumannii（MDRAB）continues to decrease,and AB infection has become a major threat to nosocomial infections worldwide[1].According to national statistics,the average drug resistance rate of AB to carbapenems was 54.3%,an increase of 0.6 percentage points compared with 53.7%in 2020,indicating that the drug resistance situation was still extremely severe.imipenem（IPM）belongs to carbapenems,which is a kind of broad-spectrum and efficientβ-lactam antibiotics with strong antibacterial activity against AB.However,with the wide application of clinical treatment,the drug resistance rate has been on the rise in recent years[2],which greatly limits the therapeutic effect and the selection of antibiotics.The drug resistance of AB in our hospital in 2022 was analyzed statistically,42 strains of IRAB and 17 strains of ISAB were collected in our hospital,and the antibiotic resistance of AB was further analyzed,and then PCR amplification of IPM resistance related gene elements was carried out to conduct a deeper study on the drug resistance mechanism of IRAB,and to speculate the combination of drug resistance mechanism of IRAB in our hospital.1.Analysis of AB resistance in our hospital1.1 Analysis of AB resistance in our hospital in 2022Method:The detection rate of AB and drug resistance rate of IPM in our hospital in 2022 were analyzed,and the drug sensitivity of commonly used antibiotics was analyzed.Results:1.In 2022,a total of 464 strains of AB and 239 strains of IRAB were detected in our hospital,and the drug resistance rate of IPM could reach 51.5%.2.MDRAB in our hospital was resistant to 16 of the 18 commonly used antibiotics,and was only sensitive to tigacycline and colistin,but was seriously resistant to minocycline and cefoperazone sulbactam.3.There was statistical significance in drug resistance rate between MDRAB（n=244）group and non-Mdrab（n=220）group（P<0.05）.1.2 Analysis of drug resistance of 59 isolates of AB Method:A total of 60 strains of AB in our hospital from April 2022 to October 2022 were collected and identified by morphology,mass spectrometer,intrinsic genes and other aspects（1 strain was identified and the sample was removed）.After drug sensitivity test by K-B AGAR disk diffusion method,42 strains of IRAB and 17 strains of ISAB were divided into two groups.Drug resistance of 59 isolated samples was analyzed first,and then the next part of the experiment was carried out.Results:1.In IRAB 1.42 strains,the drug resistance rates of quinolones and aminoglycosides were higher,and doxycycline,tigacycline and colistin were all sensitive.Quinolones:about 90.5%（38/42）resistant,about 7%（3/42）intermediary;Aminoglycosides:about 90.5%（38/42）resistant,about 7%（3/42）sensitive;Tetracycline class:About 33.3%（14/42）showed intermediation for minocycline.2.17 strains of ISAB had high drug resistance to cephalosporins and were sensitive to other commonly used antibiotics.About 70.6%（12/17）were resistant to ceftriaxone,and even about 11.8%（2/17）were resistant to ceftriaxone,about 6%（1/17）were resistant to ceftazidime,and about 23.5%（4/17）were resistant to piperacillin.2.Study on the related gene elements of AB resistance to IPM Method:The positive rates of the IPM-resistant genes bla OXA-51,bla OXA-23,Amp C,Abe M,Car O and Dac D in 42 IRAB and 17 ISAB strains were detected by PCR,respectively,to study whether there was statistical significance in the positive rates between the two groups.The insertion sequence IS Aba1 and IS Aba125 were further amplified,and the drug resistance mechanism of IRAB in our hospital was speculated based on the experimental results.Results:1.bla OXA-51 was an inherent AB gene with a positive rate of 100%.2.The positive rate of bla OXA-23,Amp C,Car O,Abe M,Dac D and IS Aba1 genes was higher in IRAB group,while the positive rate of IS Aba125 gene was lower.The positive rate was 88%（37/42）for bla OXA-23,90.5%（38/42）for Amp C and Car O,81%（34/42）for Abe M,93%（39/42）for Dac D and IS Aba1.The positive rate of IS Aba125 was 24%（10/42）.3.The positive rate of genes Amp C and IS Aba1 was higher in ISAB group,while the positive rate of genes bla OXA-23,Abe M,Car O,Dac D and IS Aba125 was lower.The positive rate was 41%（7/17）for bla OXA-23,76.5%（13/17）for Amp C,52.9%（9/17）for Abe M,47.1%（8/17）for Car O and 58.8%（10/17）for Dac D.The positive rate of IS Aba1 was 88%（15/17）and IS Aba125 was 35%（6/17）.Conclusion:1.AB in our hospital presents multi-drug resistance and pan-drug resistance,and the level of drug resistance to carbapenems and cephalosporins is high.Antibiotic use strategies in our hospital need to be adjusted to prevent the development of drug resistance.2.blaOXA-23（benzoxicillin enzyme）,Abe M（efflux pump related gene）,Car O（channel protein related gene）,Dac D（penicillin binding protein related gene）were correlated with IRAB resistance,while Amp C gene（Class Cβlactamase related gene）、IS Aba1、IS Aba125（Insertion sequence-related genes）was not correlated with IRAB resistance.3.The insertion sequence may require the activation of the underlying activation mechanism or the expression level of the gene to influence the resistance of carbapenem antibiotics.4.According to the results of PCR and statistical analysis,it can be inferred that the mechanism of IRAB resistance in our hospital is mainly mediated by the changes of benzoxicillin enzyme,channel protein and penicillin-binding protein,and the synergistic effect of effector pump. |
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