Beta-Lactamase Gene Expression Level of Hospital-Acquired CRAB Isolated from Children in Picu

PURPOSE: Acinetobacter baumannii is a major cause of hospital-acquired infections. Studies showed that carbapenem resistance was related to mortality. Carbapenem resistance depends on expression of β-lactamase in adults. The present study explores the relationship between β-lactamase gene expression and carbapenem resistance and outcomes in children with A. baumannii infections. PATIENTS AND METHODS: We gathered clinical data of 131 children diagnosed with hospital-associated A. baumannii infections from the pediatrics unit of Shengjing Hospital of China Medical University. We obtained 131 isolates of A. baumannii, determined the minimal inhibitory concentrations (MICs) for common antibiotics, and measured carbapenemase-encoding genes expression using real-time PCR. RESULTS: We isolated 131 strains, 89 of which were carbapenem-resistant (MIC ≥ 8 µg/mL), and 42 carbapenem-sensitive strains. Univariate analysis identified statistically significant differences between the carbapenem-resistant group and the carbapenem-sensitive group for in-hospital days before infection, previous deep vein catheterization, previous urinary catheterization, previous treatment with a carbapenem (meropenem/imipenem), and expression of oxa-51 and oxa-23. Logistic regression analysis of factors associated with carbapenem-resistant A. baumannii infections found significant associations with oxa-23 expression (hazard ratio [HR] 0.005, confidence interval [CI] 95% 0–0.153, P = 0.002) and previous carbapenem treatment (HR 0.031 CI 95% 0.1–0.959, P = 0.042). Of 131 patients, 27 died within 30 days. Cox regression analysis of factors associated with 30-day mortality from A.baumannii infections showed that cephalosporin combined with sulbactam (HR 0.271, CI 95% 0.101–0.723, P = 0.009) was associated with 30-day survival. CONCLUSION: The expression of oxa-23 and the use of carbapenems were independent risk factors for carbapenem resistance. The use of cephalosporins combined with sulbactam was independently associated with 30-day survival. We recommend using cephalosporins combined with sulbactam in children infected with A. baumannii.