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 .
Keywords: β-lactamase geen, carbapenem resistance, Acinetobacter baumannii , prognosis, risk factors