Molecular epidemiology of Acinetobacter baumannii containing IMP-4 and OXA-23 isolated in children / 中华检验医学杂志

ABSTRACT

Objective To investigate the molecular epidemiology of CRAB isolated from children in wuhan. Methods Forty non-repetitive strains of CRAB were collected from hospitalized children of emergency department, neonatal medicine, cardiothoracic surgery, bone surgery, respiratory medicine and renal medicine in Wuhan children's hospital during December 2008 and May 2009. MIC values were PFGE; KPC, IMP, GIM, SPM, SIM, OXA-23, VIM genes and integrase gene were amplified by PCR and then sequenced to confirm the genotypes.; Plasmid conjugation experiment was used to study the transfer method of bacterial resistance and southern blot hybridization was used to target the resistance genes. Results Susceptible rates of 40 strains to gentamicin, tobramycin, amikacin, ciprofloxacin, levofloxacin, trimoxazole were 20%, 5%, 93%, 93%, 95%, and 23% respectively. Eleven types of clone were detected by PFGE,including 29 strains of type A clone, 2 strains of type B clone, and 1 strain for each type of C to K clone. Eleven isolates produced both IMP-4 and OXA-23 carbapemase. Twenty-six isolates only possessed OXA-23 carbapemase. Thirty-six strains carried class Ⅰ integron. The results of southern blot hybridization showed that Intl, IMP-4 and OXA-23 type were located on chromosome. Conclusions Type A clone of CRAB is the most common. OXA-23 and IMP-4 type are the major acquired carbapemases, especially the OXA-23 is the most common type. The horizontal transmission of OXA-23 and IMP-4 gene mediated by Int1 and the spread of type A resistant clone is the major way of the spread of carbapenem-resistant Acinetobacter baumannii in the region.