Mechanical ventilation-associated pneumonia caused by Acinetobacter baumannii in Northeast China region: analysis of genotype and drug resistance of bacteria and patients\u2019 clinical features over 7\xa0years

Tao Zhang,Xiao Xu,Wei Xu,Cai-Fang Xu,Salisu Rabiu Bilya

doi:10.1186/s13756-021-01005-7

Abstract

ObjectiveTo 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.MethodsClinical 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.ResultsThe 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.ConclusionIn 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.

Highlights

Acinetobacter baumannii (Ab) is a type of non-sugarfermenting Gram negative bacillus
According to inclusion and exclusion criteria, 105 patients with ventilation-associated pneumonia (VAP) caused by hospital-acquired Ab infection were eligible for this study
These patients had a median age of 27 months, of which 77.1% were admitted to hospital for infectious disease and nearly 50% had underlying disease; Ab strain samples were mainly collected from the sputum and accounted for 75% of all samples; the median total mechanical ventilation time, total administration

Summary

Introduction

Acinetobacter baumannii (Ab) is a type of non-sugarfermenting Gram negative bacillus. It can adapt to the environment and is a common pathogenic bacterium in hospital-acquired infections. A. baumannii infection usually occurs in critical patients within the intensive care unit (ICU), where it may induce mechanical. As reported by China’s antimicrobial resistance surveillance system in 2019, Ab was ranked No 4 among clinically isolated Gram negative strains and accounted for 9.7% of all isolated Gram negative strains. Since critical pediatric patients often have immune deficiency and severe underlying disease, and require long-time hospitalization and invasive procedures, the incidence rate of Ab infection and the drug resistance rate of Ab are generally higher in a pediatric intensive care unit (PICU) than in other wards [3, 4]. A. baumannii has become a major conditioned pathogenic bacterium of VAP in several PICUs and accounts for 34.7–47.0% of isolated strains [5, 6]

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