Analysis of polymyxin susceptibility in Enterobacteriaceae / 中国感染与化疗杂志

ABSTRACT

Objective To investigate the distribution and antimicrobial susceptibility of clinical strains ofEnterobacteriaceae isolated from Huashan Hospital in 2014.MethodsEnterobacteriaceae were isolated from January to August 2014. Antimicrobial susceptibility testing was performed by agar dilution method. TheblaKPC gene was screened by PCR and DNA sequencing. Results were analyzed by WHONET 5.6 software.Results A total of 719 strains ofEnterobacteriaceae were collected, of whichKlebsiella spp., andE .coli accounted for 43.8% (315/719) and 30.4% (219/719), respectively. Resistance rates ofKlebsiella spp.,E. coli, andCitrobacter spp., to polymyxin B and polymyxin E were low (<3%). The percentage of theEnterobacter strains resistant to polymyxin B and polymyxin E was 10.9% and 11.1%, respectively. About 47.5% and 44.7% of theSerratia strains were resistant to polymyxin B and polymyxin E, respectively. More than 90% of theMorganella andProteus isolates were resistant to polymyxin B or polymyxin E. The carbapenem-resistantEnterobacteriaceae strains were mainly identiifed inKlebsiella isolates, more than 40% of which were resistant to meropenem and ertapenem, but only 2.9% and 2.6% were resistant to polymyxin B and polymyxin E, respectively. Ertapenem resistance was identified in 27.8% of theCitrobacter isolates and 17.9% of theSerratia isolates. Less than 10% of the otherEnterobacteriaceae strains were resistant to carbapenem. Overall, 20.7% (149/719) of the isolates wereblaKPC positive, mainly inK. pneumoniae (129/315, 41.0%). Seven strains ofSerratia marcescens and 2 strains ofK. Pneumoniae were resistant to both carbapenems and polymyxin.Conclusions The clinical isolates ofKlebsiella, E. coli, Enterobacter andCitrobacter in 2014 were still highly susceptible to polymyxin antibiotics.