Prevalence and phenotypic characterization of carbapenem-resistant Klebsiella pneumoniae strains recovered from sputum and fecal samples of ICU patients in Zhejiang Province, China

Ling-bin Shu,1,* Qun Lu,2,* Ren-hua Sun,3 Le-qing Lin,4 Qiao-ling Sun,1 Jie Hu,1 Hong-wei Zhou,1 Edward Wai-Chi Chan,5,6 Sheng Chen,5,6 Rong Zhang11Department of Clinical Laboratory Medicine, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China; 2Department of Hospital Infection Management, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China; 3Department of Critical Care Medicine, Zhejiang Provincial People’s Hospital, People’s Hospital of Hangzhou Medical College, Hangzhou, China; 4Department of Intensive Care Unit, The Affiliated Hospital of Hangzhou Normal University, Hangzhou, China; 5Shenzhen Key Lab for Food Biological Safety Control, Food Safety and Technology Research Center, Hong Kong PolyU Shen Zhen Research Institute, Shenzhen, China; 6State Key Lab of Chirosciences, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong *These authors contributed equally to this work Objective: To understand the prevalence and transmission of carbapenem-resistant Klebsiella pneumoniae (CRKP) in ICU patients in Zhejiang Province, China, and determined the genetic and phenotypic characteristics of these CRKP strains. Materials and Methods: A total of 202 ICU patients from eight tertiary hospitals were recruited and 55 non-duplicate CRKP strains were collected during July and August in 2017. These strains were subjected to determination of MICs, carriage of carbapenemase genes and tet(A) variants, PFGE, MLST and virulence potential using G. mellonella larvae infection model. Results: A total of 55 CRKP strains were recovered from 42 patients, representing a carriage rate of 20.8%. CRKP strains were recovered from both the intestinal and respiratory tract of 13 patients. Importantly, strains isolated from sputum and fecal samples often displayed identical PFGE profiles, suggesting that CRKP may also colonize the respiratory tract. The most dominant ST type of these CRKP strains was ST11, accounting for 78% (43/55) of the test strains. The majority of CRKP strains were resistant to multiple antibiotics, with the exception of tigecycline and ceftazidime/avibactam. Interestingly, 32 strains were found to harbor the tet(A) variant, which is known to confer reduced tigecycline susceptibility. Assessment of the virulence potential of these CRKP strains by string test showed that results were negative for 53 of the 55 test strains. However, further assessment of virulence potential using a G. mellonella larvae infection model showed that CRKP isolated from sputum consistently exhibited a higher virulence level than strains recovered from fecal samples. Conclusion: CRKP is highly prevalent in ICU patients in Zhejiang Province with strains isolated from respiratory exhibiting higher virulence potential than those from GI tract. These data provide essential insight into development of new infection control measures to halt the transmission of CRKP in clinical settings. Keywords: carbapenem-resistant Klebsiella pneumoniae, surveillance, sputum, feces, ICU, resistance, virulence