Objective:To analyze the evolution of ceftazidime/avibactam (CZA) resistance phenotyes and clinical features of 11 ST11-KL64 carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates carrying bla KPC. Methods:Eleven CRKP isolates, designated K01 to K11, obtained from infected liver transplant patients from June to September 2024 were retrospectively studied. Broth microdilution method, whole genome sequencing (WGS) and plasmid conjugation assays were employed to investigate the antimicrobial susceptibility, resistance mechanisms, and genetic structural characteristics of these CRKP isolates. Clinical data were simultaneously collected and organized to analyze the correlation between bla KPC gene mutations and the clinical efficacy of antimicrobial therapy. Results:All eleven isolates of CRKP exhibited multidrug resistance phenotypes. Among them, K01-K09 and K11 were sensitive to CZA and resistant to carbapenems, while K10 was resistant to CZA and displayed sensitivity or intermediate resistance to carbapenems. WGS analysis showed that all 11 CRKP isolates belonged to the ST11-KL64 clonal type. Among these isolates, the K01-K09 and K11 isolates carry the bla KPC-2 gene, whereas the K10 isolate carries the bla KPC-33 gene. A single nucleotide mutation in bla KPC-2 (G532T) resulted in a substitution of tyrosine (Y) for aspartic acid (D) at Ambler position 179 (D179Y), causing resistance of CRKP to CZA and reduced sensitivity to Imipenem and Meropenem. The conjugative plasmid was successfully constructed, and compared to the parental strain, its minimum inhibitory concentration (MIC) to CZA increased 32 folds. Clinical data revealed that the patient developed the bla KPC-33 mutation after 51 days of CZA treatment. Conclusions:The bla KPC-33 mutation following CZA treatment for CRKP infection exhibits a considerable delay. It is essential to dynamically monitor the evolution of CRKP resistance to ensure timely adjustment of therapeutic strategies in case of the occurrence of mutations such as bla KPC-33.

Objective To construct the K64 capsule depolymerase recombinant protein,Dep44,and investigate its potential application against carbapenem-resistant Klebsiella pneumoniae(CRKP)infections.Methods The de-polymerase-encoding phage vB_Kpn_HF1013(GenBank:PP803128)was isolated and genomically analyzed to screen for candidate depolymerases.The recombinant protein Dep44 was constructed and functionally verified for depolymerase activity.Dep44 sensitive range was validated and Dep44 antimicrobial activity was assessed by bio-film disruption and serum sterilization assays.Results The tail spike protein of phage vB_Kpn_HF1013 exhibited depolymerase activity and recombinant protein Dep44 specifically degraded K64 CRKP capsule.Biofilm eradication assays demonstrated that recombinant Dep44 at both 2 μg/mL and 10 μg/mL significantly disrupted bacterial bio-films relative to the control.Serum bactericidal assays showed that Dep44 exhibited synergistic activity with serum,dependent on the complement system,as Dep44 alone lacked bactericidal properties.Conclusion Dep44 effec-tively targets and degrades K64 CRKP capsule,disrupts biofilms,and enhances serum bactericidal activity,high-lighting its potential for managing K64 CRKP infections and clearing biofilms from medical devices.

Objective To construct the K64 capsule depolymerase recombinant protein,Dep44,and investigate its potential application against carbapenem-resistant Klebsiella pneumoniae(CRKP)infections.Methods The de-polymerase-encoding phage vB_Kpn_HF1013(GenBank:PP803128)was isolated and genomically analyzed to screen for candidate depolymerases.The recombinant protein Dep44 was constructed and functionally verified for depolymerase activity.Dep44 sensitive range was validated and Dep44 antimicrobial activity was assessed by bio-film disruption and serum sterilization assays.Results The tail spike protein of phage vB_Kpn_HF1013 exhibited depolymerase activity and recombinant protein Dep44 specifically degraded K64 CRKP capsule.Biofilm eradication assays demonstrated that recombinant Dep44 at both 2 μg/mL and 10 μg/mL significantly disrupted bacterial bio-films relative to the control.Serum bactericidal assays showed that Dep44 exhibited synergistic activity with serum,dependent on the complement system,as Dep44 alone lacked bactericidal properties.Conclusion Dep44 effec-tively targets and degrades K64 CRKP capsule,disrupts biofilms,and enhances serum bactericidal activity,high-lighting its potential for managing K64 CRKP infections and clearing biofilms from medical devices.

Objective:To analyze the evolution of ceftazidime/avibactam (CZA) resistance phenotyes and clinical features of 11 ST11-KL64 carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates carrying bla KPC. Methods:Eleven CRKP isolates, designated K01 to K11, obtained from infected liver transplant patients from June to September 2024 were retrospectively studied. Broth microdilution method, whole genome sequencing (WGS) and plasmid conjugation assays were employed to investigate the antimicrobial susceptibility, resistance mechanisms, and genetic structural characteristics of these CRKP isolates. Clinical data were simultaneously collected and organized to analyze the correlation between bla KPC gene mutations and the clinical efficacy of antimicrobial therapy. Results:All eleven isolates of CRKP exhibited multidrug resistance phenotypes. Among them, K01-K09 and K11 were sensitive to CZA and resistant to carbapenems, while K10 was resistant to CZA and displayed sensitivity or intermediate resistance to carbapenems. WGS analysis showed that all 11 CRKP isolates belonged to the ST11-KL64 clonal type. Among these isolates, the K01-K09 and K11 isolates carry the bla KPC-2 gene, whereas the K10 isolate carries the bla KPC-33 gene. A single nucleotide mutation in bla KPC-2 (G532T) resulted in a substitution of tyrosine (Y) for aspartic acid (D) at Ambler position 179 (D179Y), causing resistance of CRKP to CZA and reduced sensitivity to Imipenem and Meropenem. The conjugative plasmid was successfully constructed, and compared to the parental strain, its minimum inhibitory concentration (MIC) to CZA increased 32 folds. Clinical data revealed that the patient developed the bla KPC-33 mutation after 51 days of CZA treatment. Conclusions:The bla KPC-33 mutation following CZA treatment for CRKP infection exhibits a considerable delay. It is essential to dynamically monitor the evolution of CRKP resistance to ensure timely adjustment of therapeutic strategies in case of the occurrence of mutations such as bla KPC-33.

Objective To discuss the relationship between the diameter of portal vein and esophagogastric variceal bleeding and the severity of liver cirrhosis by CT portal venography ( CTPV). To analyze the occurence about esophagogastric variceal bleeding under in different liver cirrhosis degree. Methods 60 patients of portal hyperten-sion with liver cirrhosis and 15 healthy volunteers (controls). According to Child-Pugh classification, 60 patients were divided into Child-Pugh A,B and C groups,According to the patients whether the esophagogastric variceal bleeding or not, it was divided into two groups that esophagogastric variceal bleeding (EVB) and no EVB. All of patients underwent with 64-slice spiral CT. Image post-processing techniques such as MIP, VR, MPR and SSD were applied to measuring the diameters of portal venous system vessels and depict the portosystemic collaterals of portal venous system. Results The diameters of the right branch of portal vein and super mesenteric vein were no statisti-cal significance between bleeding group and no bleeding group. The rest parameters of portal system in EVB group are all larger than those of no EVB group(P<0.05). Age and gender in two groups had no statistic significance. All diameters of portal system in cirrhotic group were all larger than those of control group(P<0.05). In different liver function,there are differences in each groups of diameter. The bleeding rate of different groups according to he-patic function showed statistical significance(P <0.05), higher the degree of liver cirrhosis, higher the bleeding rate. Conclusion The diameters of portal system in EVB group are larger than no EVB. All diameters of portal sys-tem in cirrhotic group are all larger than those of control group. There is difference the diameter of vascular in differ-ent hepatic function. Different degree of liver cirrhosis can predict the esophagogastric variceal bleeding.