BACKGROUND Klebsiella pneumoniae(K.pneumoniae)used to affect mainly people with compromised immunity or weakened by other infections,but recent emergence of hypervirulent strains has increased infections even in healt...BACKGROUND Klebsiella pneumoniae(K.pneumoniae)used to affect mainly people with compromised immunity or weakened by other infections,but recent emergence of hypervirulent strains has increased infections even in healthy individuals.These infections include liver abscess,pneumonia,bacteremia,meningitis,necrotizing fasciitis,and endophthalmitis.Although metastatic infection by hypervirulent K.pneumoniae(hvKP)is increasingly recognized,co-infection with Cryptococcus neoformans(C.neoformans)meningitis in immunocompetent hosts is rare but fatal.So,it is necessary to determine the risk factors,complications,and comorbidity of this disease.CASE SUMMARY This report describes a 58-year-old man with hvKP pulmonary abscess,bacteremia,and meningitis,accompanied by fatal Cryptococcus meningitis.This patient presented with fever for 1 wk and drowsiness for 3 d.Laboratory findings revealed pulmonary abscess and bacteremia of K.pneumoniae.He was given intravenous antibiotic therapy,and the infection was under control for about 1 wk.However,his condition deteriorated rapidly because of metastatic purulent meningitis.Although hvKP and C.neoformans were isolated and confirmed,the patient died of spontaneous respiratory and cardiac arrest caused by cerebral hernia.CONCLUSION HvKP has emerged as a cause of metastatic infections in immunocompetent hosts.polymicrobial co-infections should be taken into consideration when metastatic infection is present.展开更多
Pseudomonas aeruginosa is a significant pathogen mainly causing healthcare-associated infections(HAIs).Newly emerging high-risk clones of P.aeruginosa with elevated virulence profiles furtherly cause severe community-...Pseudomonas aeruginosa is a significant pathogen mainly causing healthcare-associated infections(HAIs).Newly emerging high-risk clones of P.aeruginosa with elevated virulence profiles furtherly cause severe community-acquired infections(CAIs).Usually,it is not common for P.aeruginosa to co-carry exoU and exoS genes,encoding two type III secretion system(T3SS)effectors.The pathogenicity mechanism of exoS+/exoU+strains of P.aeruginosa remains unclear.Here,we provide detailed evidence for a subset of hypervirulent P.aeruginosa strains,which abundantly co-express and secrete the T3SS effectors ExoS and ExoU.The exoS+/exoU+P.aeruginosa strains were available to cause both HAIs and CAIs.The CAI-associated strains could elicit severe inflammation and hemorrhage,leading to higher death rates in a murine acute pneumonia model,and had great virulence potential in establishing chronic infections,demonstrating hypervirulence when compared to PAO1(exoS+/exoU-)and PA14(exoS-/exoU+).Both ExoS and ExoU were co-expressed and co-secreted in abundance in exoS+/exoU+strains.Their abundant protein secretion could boost exoS+/exoU+strains’potentials for cytotoxicity in vitro and pathogenicity in vivo.Genomic evidence indicates that exoU acquisition is likely mediated by horizontal gene transfer(HGT)of the pathogenicity island PAPI-2,while deletion of exoU was sufficient to mitigate virulence in the exoS+/exoU+strains.Furthermore,bioinformatics analysis showed that such exoS+/exoU+P.aeruginosa strains turned out to be widely distributed across the globe.Overall,the research provide detailed evidence for the high virulence and epidemicity of exoS+/exoU+strains of P.aeruginosa,highlighting an urgent need for surveillance against these high-risk hypervirulent strains.展开更多
Importance Hypervirulent variants of Klebsiella pneumoniae(hvKp)are capable of causing life-threatening pyogenic liver abscesses(PLAs),but hvKp caused PLAs was seldom reported in pediatric populations.Hence,there is a...Importance Hypervirulent variants of Klebsiella pneumoniae(hvKp)are capable of causing life-threatening pyogenic liver abscesses(PLAs),but hvKp caused PLAs was seldom reported in pediatric populations.Hence,there is an urgent need to raise our awareness of this phenomenon in pediatric populations.Objective This study aimed to report the clinical characteristics of hvKp that caused fatal PLA complicated by bacteremia in an adolescent and further identify the microbiological and genomic features of the causative strain.Methods A 14-year-old boy with diabetes mellitus was admitted to our hospital with a diagnosis of PLA complicated by bacteremia.A hypermucoviscous hvKp strain,KPN_19-106,was isolated from the drainage fluid present within the liver abscess cavity and blood.The hypermucoviscosity phenotype of the causative strain was determined by string test.Its virulence was measured using serum resistance assay and Galleria mellonella larvae-killing assay.Antimicrobial susceptibility was determined by broth microdilution method.Genetic information was obtained by whole-genome sequencing and bioinformatics analysis.Results KPN_19-106 belonged to sequence type 380 and serotype K2 and exhibited stronger serum resistance and higher in vivo lethality than the well-characterized hvKp NTUH-K2044 strain.Although KPN_19-106 is susceptible to most antibiotics,no sign of improvement was observed during treatment with such drugs.Whole-genome sequencing revealed that the isolate had integrated multiple mobile genetic elements related to virulence.Interpretation Antibiotic-susceptible hvKp can cause fatal PLA complicated by bacteremia in adolescents,with no improvement during antimicrobial therapy.The causative strain in this case had integrated multiple virulence genes and thus exhibited higher virulence both in vitro and in vivo when compared with NTUH-K2044.展开更多
To determine passive haemagglutination (PHA) antibody titer that would protect chicks against Nigerian isolates of the Infectious Bursa Disease Virus (IBDV), five groups of chicks aged 30 days which had different anti...To determine passive haemagglutination (PHA) antibody titer that would protect chicks against Nigerian isolates of the Infectious Bursa Disease Virus (IBDV), five groups of chicks aged 30 days which had different antibody titers were challenged with a Nigerian isolate of virulent IBDV. Mortality rates of the different groups were plotted against their respective mean PHA antibody titers. A group with zero antibody titer had a mortality rate of 75% while those with PHA antibody titers of 185.6, 243.2, 256 and 307.2 had mortality rates of 40%, zero, zero and zero respectively. Linear equation generated for a line of best fit of the graph of mortality rates of the chicks on their IBD antibody titers gave antibody titer (X) at which mortality (Y) would be zero as 300. A mortality of 75% and the high antibody level needed to protect chicks suggest that the isolate may be a hypervirulent strain.展开更多
基金Supported by Science and Technology Planning Project of Guangdong Province of China,No.2017A020215177
文摘BACKGROUND Klebsiella pneumoniae(K.pneumoniae)used to affect mainly people with compromised immunity or weakened by other infections,but recent emergence of hypervirulent strains has increased infections even in healthy individuals.These infections include liver abscess,pneumonia,bacteremia,meningitis,necrotizing fasciitis,and endophthalmitis.Although metastatic infection by hypervirulent K.pneumoniae(hvKP)is increasingly recognized,co-infection with Cryptococcus neoformans(C.neoformans)meningitis in immunocompetent hosts is rare but fatal.So,it is necessary to determine the risk factors,complications,and comorbidity of this disease.CASE SUMMARY This report describes a 58-year-old man with hvKP pulmonary abscess,bacteremia,and meningitis,accompanied by fatal Cryptococcus meningitis.This patient presented with fever for 1 wk and drowsiness for 3 d.Laboratory findings revealed pulmonary abscess and bacteremia of K.pneumoniae.He was given intravenous antibiotic therapy,and the infection was under control for about 1 wk.However,his condition deteriorated rapidly because of metastatic purulent meningitis.Although hvKP and C.neoformans were isolated and confirmed,the patient died of spontaneous respiratory and cardiac arrest caused by cerebral hernia.CONCLUSION HvKP has emerged as a cause of metastatic infections in immunocompetent hosts.polymicrobial co-infections should be taken into consideration when metastatic infection is present.
基金supported by grants from the National Key R&D Program of China(2021YFC2302005)the Joint Funds of the International Development Research Center of Canada(109282-001)the National Key R&D Program of China(2021YFC2301004 and 2017YFE0125600).
文摘Pseudomonas aeruginosa is a significant pathogen mainly causing healthcare-associated infections(HAIs).Newly emerging high-risk clones of P.aeruginosa with elevated virulence profiles furtherly cause severe community-acquired infections(CAIs).Usually,it is not common for P.aeruginosa to co-carry exoU and exoS genes,encoding two type III secretion system(T3SS)effectors.The pathogenicity mechanism of exoS+/exoU+strains of P.aeruginosa remains unclear.Here,we provide detailed evidence for a subset of hypervirulent P.aeruginosa strains,which abundantly co-express and secrete the T3SS effectors ExoS and ExoU.The exoS+/exoU+P.aeruginosa strains were available to cause both HAIs and CAIs.The CAI-associated strains could elicit severe inflammation and hemorrhage,leading to higher death rates in a murine acute pneumonia model,and had great virulence potential in establishing chronic infections,demonstrating hypervirulence when compared to PAO1(exoS+/exoU-)and PA14(exoS-/exoU+).Both ExoS and ExoU were co-expressed and co-secreted in abundance in exoS+/exoU+strains.Their abundant protein secretion could boost exoS+/exoU+strains’potentials for cytotoxicity in vitro and pathogenicity in vivo.Genomic evidence indicates that exoU acquisition is likely mediated by horizontal gene transfer(HGT)of the pathogenicity island PAPI-2,while deletion of exoU was sufficient to mitigate virulence in the exoS+/exoU+strains.Furthermore,bioinformatics analysis showed that such exoS+/exoU+P.aeruginosa strains turned out to be widely distributed across the globe.Overall,the research provide detailed evidence for the high virulence and epidemicity of exoS+/exoU+strains of P.aeruginosa,highlighting an urgent need for surveillance against these high-risk hypervirulent strains.
基金Beijing Municipal Administration of Hospitals Clinical Medicine Development of Special Funding Support(grant number ZYLX201813).
文摘Importance Hypervirulent variants of Klebsiella pneumoniae(hvKp)are capable of causing life-threatening pyogenic liver abscesses(PLAs),but hvKp caused PLAs was seldom reported in pediatric populations.Hence,there is an urgent need to raise our awareness of this phenomenon in pediatric populations.Objective This study aimed to report the clinical characteristics of hvKp that caused fatal PLA complicated by bacteremia in an adolescent and further identify the microbiological and genomic features of the causative strain.Methods A 14-year-old boy with diabetes mellitus was admitted to our hospital with a diagnosis of PLA complicated by bacteremia.A hypermucoviscous hvKp strain,KPN_19-106,was isolated from the drainage fluid present within the liver abscess cavity and blood.The hypermucoviscosity phenotype of the causative strain was determined by string test.Its virulence was measured using serum resistance assay and Galleria mellonella larvae-killing assay.Antimicrobial susceptibility was determined by broth microdilution method.Genetic information was obtained by whole-genome sequencing and bioinformatics analysis.Results KPN_19-106 belonged to sequence type 380 and serotype K2 and exhibited stronger serum resistance and higher in vivo lethality than the well-characterized hvKp NTUH-K2044 strain.Although KPN_19-106 is susceptible to most antibiotics,no sign of improvement was observed during treatment with such drugs.Whole-genome sequencing revealed that the isolate had integrated multiple mobile genetic elements related to virulence.Interpretation Antibiotic-susceptible hvKp can cause fatal PLA complicated by bacteremia in adolescents,with no improvement during antimicrobial therapy.The causative strain in this case had integrated multiple virulence genes and thus exhibited higher virulence both in vitro and in vivo when compared with NTUH-K2044.
文摘To determine passive haemagglutination (PHA) antibody titer that would protect chicks against Nigerian isolates of the Infectious Bursa Disease Virus (IBDV), five groups of chicks aged 30 days which had different antibody titers were challenged with a Nigerian isolate of virulent IBDV. Mortality rates of the different groups were plotted against their respective mean PHA antibody titers. A group with zero antibody titer had a mortality rate of 75% while those with PHA antibody titers of 185.6, 243.2, 256 and 307.2 had mortality rates of 40%, zero, zero and zero respectively. Linear equation generated for a line of best fit of the graph of mortality rates of the chicks on their IBD antibody titers gave antibody titer (X) at which mortality (Y) would be zero as 300. A mortality of 75% and the high antibody level needed to protect chicks suggest that the isolate may be a hypervirulent strain.
基金supported by the National Natural Science Foundation of China(32141001 and 31830001)the National Science Fund for Distinguished Young Scholars(32125003)the National Key R&D Program of China(2022YFC2303900 and 2022YFC3704700)。
