ABSTRACT
Objective@#To establish a Galleria mellonella model of liver abscess-related Klebsiella pneumoniae (K.pneumoniae) infection and to evaluate its feasibility for virulence detection.@*Methods@#Twelve liver abscess-related K. pneumoniae strains were collected in Wuxi No.2 People′s Hospital from January 2016 to December 2017. Twenty K. pneumoniae strains isolated from sputum and urine samples were used as classic strains. All isolates were analyzed by String test. Common capsular serotypes (K1, K2, K5, K16, K20, K54 and K57) of highly virulent K. pneumoniae strains were detected by PCR. Virulence test was performed to measure 80% lethal doses (LD80) of different serotypes in the same time period and the lethal time for 80% of larvae (LT80) at the same concentration.@*Results@#The 12 strains of liver abscess-related K. pneumoniae belonged to five serotypes, which were K1 (41.7%, 5/12), K2 (8.3%, 1/12), K5 (8.3%, 1/12), K20 (8.3%, 1/12) and K57 (33.4%, 4/12). High-virulence serotypes were not detected in the classic group. The positive rates of String test in the liver abscess group and the classic group were 75% and 10% (2/20), respectively. Results of the virulence test showed that when the concentration ranged from 1×105 CFU/ml to 1×108 CFU/ml, the lethal effects of different strains on Galleria mellonella larvae were in a concentration dependent manner. Twelve hours after infection, the numbers of dead larvae in K1 and K57 serotype groups were significantly higher than those in K2, K5, K20 and classic groups. The LD80 values of the liver abscess group at 96 hours after infection were as follows: 1×106 CFU/ml (K1, K57) and 1×107 CFU/ml (K2, K5, K20).@*Conclusion@#The liver abscess-related K. pneumoniae isolates are all highly virulent strains. The virulence of K. pneumoniae can be detected at 12 hours after infection of Galleria mellonella.
ABSTRACT
Objective To investigate the distribution of hypervirulent capsular serotypes and virulence genes of Klebsiella pneumoniae associated with pyogenic liver abscess(PLA),and analyze the homology of strains.Methods Twelve strains of liver abscess-related Klebsiella pneumoniae were isolated in Wuxi Second People's Hospital during January 2016 and August 2017.Among them,five were also detected in blood samples.All the strains were performed the viscous thread test,and the hypervirulent capsular serotypes and main virulence genes were detected by PCR.The homology of the strains was analyzed by the multilocus sequence types(MLST) and pulsed-field gel electrophoresis(PFGE).Results The positive rate of the viscous thread test for 12 strains of liver abscess-related Klebsiella pneumoniae was 75％.Three kinds of hypervirulent capsular serotypes,including K1 (6/12,50％),K54(1/12,8.3％) and K57(5/12,41.7％),were detected.The positive rates of virulence genes,such as wcaG,rmpA,ureA,fimH,mrkD,uge,Aer and iroNB,were all 100％,while that of iucB was 83.3％.The cf29a gene was not found,and the magA,allS and kfuBC genes were only detected in K1 serotype strains.MLST found that ST23(4/12,33.3％) and ST25(3/12,25％) were main sequence types,and then were ST412(2/12,16.7％),ST1660(1/12,8.3％),ST1049(1/t2,8.3％) and ST11 (1/12,8.3％).PFGE showed that 12 strains of Klebsiella pneumoniae were divided into 8 types,and that only 3 strains of K1 serotype belong to the same clonotype.Conclusion All the isolated liver abscess-related Klebsiella pneumoniae strains are highly virulent.ST23 and ST25 are main sequence types,and ST1049 is first reported.PFGE results show genetic diversity,and Kl-type Klebsiella pneumoniae has a certain epidemic tendency.
ABSTRACT
Pyogenic liver abscess caused by Klebsiella pneumoniae represents an ever increasing entity which has mainly been described as occurring in Asia, even though, on a smaller scale, cases are being more frequently described from the USA and Europe, 13% overall mortality being reached worldwide. Affected patients are severely sick, suffering from fever, sweating, having increased acute phase reactants and risk factors such as Diabetes Mellitus, alcoholism and the inherent characteristics of the bacteria causing the disease. Objective: in this work we used a Multilocus Sequencing Typing (MLST), a nucleotide sequence-based method in order to characterize the genetic relationships among bacterial isolates. Materials and methods: the report is focused on three cases involving patients suffering from pyogenic liver abscess caused by Klebsiella pneumoniae in two hospitals in Bogota, Colombia, where phenotyping and hypermucoviscosity studies were carried out, as well as the genotyping of cultured Klebsiella isolates. Results: it was found that the isolated microorganism in cases I and II corresponded to the same K. pneumoniae strain, having 100% sequence identity for the 5 genes being studied while the strain in Case III was genotypically different. Conclusion: it is important to carry out multidisciplinary studies allowing all pyogenic liver abscess cases reported in Colombia to be complied to ascertain the frequency of microorganisms causing this pathology in our country, as well as a genotyping study of different K. pneumoniae strains to compare them and confirm clonal and pathogenicity relationships through housekeeping gene analysis.
El absceso hepático piógeno causado por Klebsiella pneumoniae representa una entidad descrita con frecuencia en los países asiáticos y, en menor escala, también en Estados Unidos y Europa. En el ámbito mundial su mortalidad alcanza a un 13%. Los pacientes pueden presentar un compromiso severo, el cual cursa con fiebre, sudoración y aumento de reactantes de fase aguda, sobre todo en individuos con factores de riesgo como la diabetes mellitus y el alcoholismo, además de las características inherentes de la bacteria responsable de la infección. Objetivo: a continuación se presentan tres casos de pacientes con absceso hepático piógeno causado por Klebsiella pneumoniae en dos hospitales de Bogotá. Materiales y métodos: se realizó caracterización molecular de los aislados de Klebsiella mediante la técnica de Multilocus Secquence Typing (MLST), análisis fenotípicos y de hipermucoviscosidad. Resultado: se encontró que el microorganismo aislado en los casos I y II corresponde a la misma cepa de K. pneumoniae, que tiene 100% de identidad de secuencia de los 5 genes en estudio mientras que la cepa en Case III fue genotípicamente diferente. Conclusión: es importante llevar a cabo estudios multidisciplinarios que incluyan todos los casos de abscesos hepáticos piógenos reportados en Colombia con el objeto de determinar la frecuencia de los microorganismos causantes de esta patología en nuestro país, así como un estudio de genotipificación de diferentes cepas de K. pneumoniae para confirmar las relaciones clonales y de patogenicidad.
O abscesso hepático piogênico causado por Klebsiella pneumoniae representa uma entidade descrita com frequência nos países asiáticos e, em menor escala, também nos Estados Unidos e na Europa. No âmbito mundial sua mortalidade alcança um 13%. Os pacientes podem apresentar um compromisso severo, o qual cursa com febre, sudoração e aumento de reagentes de fase aguda, especialmente em indivíduos com fatores de risco como a diabetes mellitus e o alcoolismo, além das características inerentes da bactéria responsável da infecção. Objetivo: a continuação apresentamse três casos de pacientes com abscesso hepático piogênico causado por Klebsiella pneumoniae em dois hospitais de Bogotá; Materiais e métodos: realizou-se caracterização molecular dos isolados de Klebsiella mediante a técnica de Multilocus Secquence Typing (MLST), análises fenotípicas e de hipermucoviscosidade. Resultado: encontrou-se que o micro-organismo isolado nos casos I e II corresponde à mesma cepa de K. pneumoniae, que tem 100% de identidade de sequencia dos 5 genes em estudo enquanto a cepa no caso III foi genotipicamente diferente. Conclusão: é importante levar a cabo estudos multidisciplinares que incluam todos os casos de abscessos hepáticos piogênicos reportados na Colômbia com o objeto de determinar a frequência dos micro-organismos causadores desta patologia em nosso país, assim como um estudo de genotipificação de diferentes cepas de K. pneumoniae para confirmar as relações clonais e de patogenicidade.
Subject(s)
Humans , Liver Abscess , Pathology , Risk Factors , Colombia , Liver Abscess, Pyogenic , Diabetes Mellitus , Infections , Klebsiella pneumoniaeABSTRACT
Introduccion: La enfermedad neumococica es una de las principales causas de mortalidad infantil en el mundo. Ob je - tivo: Determinar los serotipos de Streptococcus pneumoniae que producen enfermedad invasiva en ninos menores de 5 anos en Venezuela. Materiales y Metodos: Se establecieron 7 hospitales centinelas. El estudio incluyo variables demograficas y epidemiologicas. El Instituto Nacional de Higiene Rafael Rangel realizo la confirmacion y serotipificacion de las cepas. Resultados: Entre 1999-2007 fueron se - ro tipificadas 493 cepas de S. pneumoniae. Los serotipos mas frecuentes fueron el 14 (34,9%), 6B (13,8%), 5 (9,1%), 1 (6,1%) y 19A (6,1%), que correspondieron al 70% de las cepas. La cobertura global de la vacuna polisacarida conjugada heptavalente seria de 66,9% en bacteriemias, 56,6% en neumonias y 64,6% en meningitis. La va cuna decavalente tendria una cobertura teorica global de 76,9%, con valores similares en las tres entidades clinicas y la trecevalente tendria una cobertura potencial teorica de 90%. Conclu sio - nes: Esta investigacion reporta la distribucion de los serotipos invasivos de S. pneumoniae en Venezuela y permiten in ferir que la introduccion de vacunas neumococicas conjugadas en nuestra poblacion pediatrica ten drian un impacto positivo en la prevencion de la enfermedad.
Background: Pneumococcal disease is the principal cause of morbidity and mortality in children. Objective: To determi - ne the serotype distribution of invasive S. pneumoniae strains isolated from children under 5 years in Venezuela. Ma terials and Methods: 7 hospitals settled down sentries. The study included demographic variables and epidemiologists. The National Institute of Higiene gRafael Rangelh rea li - sed the confirmation and serotyping of the strains. Results: Bet ween 1999-2007 493 strains of S. pneumoniae were se - ro typing. The most frequent serotypes, with 70% of all the strains belonging to these 5 serotypes were: 14 (34,9%), 6B (13,8%), 5 (9,1%), 1 (6,1%) and 19A (6,1%). The potential co verage of the 7-valent conjugate vaccine is 66,9% for bacteriemia, 56,6% for pneumonias and 64,6% for meningitis respectively. The potential coverage of the 10-valent conjugate vaccine is (76,9%) with similar values for the three clini cal manifestations and the 13-valent has a potential coverage of 90%. Conclusions: This investigation reports the distribution of invasive S. pneumoniae serotypes in Venezuela and allow to infer that the conjugated vaccines introduction in our pediatric population could have a positive impact on the prevention of pneumococcal disease.