Clinical Distribution Characters And Mechanism Of Drug Resisitance Transmition In Carbapenem Resistant Klebsiella Pneumonia Isolated From Children

Background/Aims:To investigate the clinical distribution characters and antibiotic sensitivity in Klebsiella Pneumoniae strains isolated from hospital children, and to analyse the mechanism of drug resisitance transmition in carbapenem resistant Klebsiella pneumonia isolates, which will help to provide more laboratory supports for clinical medication and infection prevention.Methods:The identification cards for VITEK automated microbiological analyzer were used for identifying bacilli isolated during September 2009 to December 2010 and the drug sensitivity cards were used for detecting antibiotic resistance and extended-spectrumβ-lactamas (ESBLs) in Klebsiella pneumoniae. A total of 16 Carbapenem-resistant Klebsiella peneumoniae strains from the children's hospital were collected during September 2009 to December 2010. Modified Hodge tests were employed to detect carbapenemase production and Imipenem-EDTA synergy tests were used to screen metallo-β-lactamase production. PCR and nucleotide sequence analysis were performed to detect carbapenem-resistant genes and corresponding genotypes. Plasmid conjugation transfer experiments were applied to study the mode of drug resistance transmission. PFGE was performed to analyse the homogeneity of genomic DNA of Klebsiella pneumoniae.Results:A total of 465 (32.77%) Klebsiella pneumoniae strains were identified froml419 non-duplicate Gram-negative bacilli. All Klebsieua pneumoniae strains were mainly isolated from sputum and Intensive Care Units. The sensitive rates of Klebsiella pneumonia to imipenem, meropenem, amikacin and levofloxacin were 96.1%,98.7%, 98.7% and 95.3%, respectively. Among 16 carbapenem-resistant Klebsiella peneumoniae strains, the positive rates for modified hodge test and EDTA synergy test were 35.7% and 100%, and 16 Klebsiella peneumoniae strains carried blaIMP-4 genes. None of blaVIM, blaKPC, blaOXA-48 and blaNDM-1 genes from 16 Klebsiella peneumoniaes were found in this study. Plasmid conjugation transfer experiments of 16 Klebsiella pneumoniae were positive. Seven types of Klebsiella pneumoniae were detected by PFGE, such as type A 6 strains including 1 strain of subtype A1, type B 3strains, type C 3 strains, and type D, E, F, G 1 strain each. Type A was the main drug resistant clones. Among 16 pediatric patients,15 had complicated diseases with respiratory tract infections,1 had Leukemia with blood-stream infection. In most cases, meropenem was taken alone or combinatiionally with other antibiotics, and 13 of 16 cases were improved.Conclusions:Klebsiella pneumoniae strains occupy the second place in isolated bacilli in the children's hospital, and theses isolates generally are highly sensitive to both imipenem and meropenem, but carbapenem-resistant Klebsiella peneumoniae isolates emerge. The type of IMP-4 Metallo-β-lactamase encoded by blaIMP-4 which may be mediated by plasmid mainly leads to Klebsiella peneumoniae strains resistant to carbapenems in this study. Multiple clones predominated as clone A of Klebsiella peneumoniae with blaIMP-4 gene prevail in different clinical departments. All these isolates are shown to resistant or reducedly sensitive to mostβ-lactam antibiotics include carbapenems, while still highly sensitive to amikacin and levofloxacin. To monitor and prevent the spread of such resistant strains, antibiotic resistance surveillance for the bacteria with resistant or reducedly susceptible to carbapenems should be enhanced and relevant effective measures should be taken.