Mechanical ventilation-associated pneumonia caused by Acinetobacter baumannii in Northeast China region: analysis of genotype and drug resistance of bacteria and patients’ clinical features over 7 years

Abstract

Objective

To investigate the clinical features and outcomes of patients with mechanical ventilation-associated pneumonia (VAP) caused by Acinetobacter baumannii (Ab), and to characterize the drug resistance of pathogenic strains and carbapenem resistance-associated genes.

Methods

Clinical data were collected from the PICU of Shengjing Hospital. Patients who met the diagnostic criteria of VAP and for whom Ab was a pathogen were selected as study participants. The patients were divided into carbapenem-resistant A. baumannii (CRAB) and carbapenem-sensitive A. baumannii (CSAB) groups. The genes closely associated with Ab resistance to carbapenems and the efflux pump-related genes were detected by real-time polymerase chain reaction, and results compared between the two groups.

Results

The total mechanical ventilation time and the administration time of antibiotics after a diagnosis of Ab infection were significantly higher in the CRAB group. And the CRAB group strains were only sensitive to amikacin, cephazolin, compound sulfamethoxazole, and tigecycline. Genetic test results indicated that IPM expression was not significantly different between two groups. The OXA-51 and OXA-23 in the CRAB group was markedly higher than that in the CSAB group, while OXA-24 expression was markedly lower. The expression of AdeABC and AdeFGH was significantly greater in the CRAB compared to CSAB group.

Conclusion

In pediatric patients with VAP caused by Ab infection, the detection rate of CRAB strains is far higher than that of CSAB strains; The abnormal expression of β-lactamase-producing genes ( OXA-23, OXA-24, and OXA-51) and efflux pump-related genes ( AdeABC and AdeFGH) is closely related to the production of CRAB.