Analysis on the clinical distribution and genomic epidemiological characteristics of carbapenem-resistant Acinetobacter baumannii

Abstract:

[Background] Acinetobacter baumannii is one of the most important pathogens causing clinical infection. Its resistance level to carbapenem antibiotics is inceasing year by year. Using genome sequencing technology to analyze the distribution and epidemiological characteristics of A. baumannii can promote the effective prevention and treatment of clinical infection.[Objective] To study the clinical distribution and genomic epidemiological characteristics of 200 carbapenem-resistant Acinetobacter baumannii (CRAB) strains detected in Cangzhou Central Hospital in 2018, aiming to provide a theoretical basis for the prevention of nosocomial infections and anti-infective treatment. [Methods] The susceptibility of 200 CRAB strains isolated from different clinical department to 16 antimicrobial agents was detected by bacterial identification and drug sensitivity analyzer; PCR amplification was used to detect the carbapenemase gene; multi-locus sequence typing (MLST) was performed to detect strains' sequence type; genomic epidemiological analysis revealed transmission relationships among strains from different department. [Results] CRAB strains was mainly distributed in emergency ICU (47.0%), respiratory department (19.5%) and critical medicine department (12.0%). The CRAB strains showed high resistant level to imipenem, meropenem, ampicillin/sulbactam, ticacillin/clavulanic acid, gentamicin, piperacillin/tazobactam, levofloxacin, ciprofloxacin, amikacin and the third and fourth generation cephalosporins (cephalosporin, ceftriaxone and cefepime) and moderate resistance to sulfamethoxazole. Most strains were still sensitive to polymyxin B, minocycline and cefoperazone/sulbactam. The PCR results of antibiotic resistance genes showed that 180 strains (90.0%) of CRAB strains carried OXA-23 gene, 19 strains (9.5%) carried OXA-24 gene, and only 1 strain carried OXA-58 gene. The results of MLST showed that except for the OXA-58 positive strain, the others were all belonged to international clonal group CC2. Genomic epidemiology analysis showed that the strains in this hospital could be divided into four groups A, B, C and D. Group D was the main epidemic group, and it was distributed in different disease areas. [Conclusions] The multidrug resistance of CRAB strain in our hospital is severe, mainly were CC2 strains carrying OXA-23 gene, and there may be infection transmission among different ward areas. The environmental cleaning work of key departments should be strengthened, the technical operation rules of medical staff should be strictly standardized, and carbapenem antibiotics should be used cautiously to reduce infection and prevent further increase of drug resistance rate.