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

Background: 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.MethodsThe 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 -qacE Delta 1, qacA/B and cepA-were determined using polymerase chain reaction.ResultsA 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 similar to 512mg/L, 64 similar to 128mg/L and 8 similar to 128mg/L, respectively. For 14 CREC strains, the MIC ranges against chlorhexidine, TCCA and PVP-I were 4 similar to 128mg/L, 64 similar to 128mg/L and 4 similar to 128mg/L, respectively. Moreover, against chlorhexidine and PVP-I, the MIC90 of 36 CRKP strains was higher than that of 50 CSKP strains. The qacEo1 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 qacE Delta 1; it reached over 80% among CRKP strains. Compared to the CSKP strains, the presence of the qacE Delta 1 and cepA genes was significantly higher among the CRKP strains (p<0.05).ConclusionCRE strains collected from patients in our hospital exhibit various degree of resistance to the commonly used chemical disinfectants. It is of great help to keep monitoring the tendency of the reduced susceptibility of the pan-resistant strains against disinfectants, in order to effectively control and prevent the spread of the super resistant bacteria.