Determining the susceptibility of carbapenem resistant Klebsiella pneumoniae and Escherichia coli strains against common disinfectants at a tertiary hospital in China

Carbapenem-resistant Enterobacteriaceae (CRE) infections have become a global health threat. Controlling CRE transmission in hospitals is increasingly dependent on the use of disinfectants to restrict the risk of infection. Here, the susceptibility of patient-derived carbapenem resistant Klebsiella pneumoniae (CRKP) and Escherichia coli (CREC) strains against three common disinfectants and the determinants of resistance to disinfectants were investigated. The minimum inhibitory concentrations (MICs) and the minimum bactericidal concentrations (MBCs) of three common chemical disinfectants: chlorhexidine, trichloroisocyanuric (TCCA) acid and Povidone iodine (PVP-I) against 50 CRE strains were measured. The drug-resistance genes -qacEΔ1, qacA/B and cepA-were determined using polymerase chain reaction. A total of 36 CRKP and 14 CREC strains were collected in our hospital from 2016 to 2018. The MIC ranges of 36 CRKP strains against chlorhexidine, TCCA and PVP-I were 8~512 mg/L, 64~128 mg/L and 8~128 mg/L, respectively. For 14 CREC strains, the MIC ranges against chlorhexidine, TCCA and PVP-I were 4~128 mg/L, 64~128 mg/L and 4~128 mg/L, respectively. Moreover, against chlorhexidine and PVP-I, the MIC of 36 CRKP strains was higher than that of 50 CSKP strains. The qacE△1 gene was detected in 15 isolates among 36 CRKP strains (41.7%), and 8 isolates among 14 CREC strains (57.1%); while the qacA/B gene was not detected. Specifically, the cepA gene was much more prevalent than the qacEΔ1; it reached over 80% among CRKP strains. Compared to the CSKP strains, the presence of the qacEΔ1 and cepA genes was significantly higher among the CRKP strains (p