RESUMO
During 1988-1990 a total of 345 virulent and avirulent strains of enteroinvasive E. coli (EIEC) were isolated from human faeces in microbiological laboratories in Prague and Sofia. This group of strains belonged to a total of 11 serotypes. The most frequently encountered serotypes in both laboratories were: 0124, 0164 and 028ac. From patients 205 strains were obtained and from healthy subjects 140 strains of EIEC. In all strains the following signs of virulence were investigated: biochemical properties, serotypes, Serény's test, test on HeLa cells, sensitivity to colicine JS and the plasmid profile. The presence of high molecular plasmid 140 MDa correlated closely with positive results of the above mentioned tests. Plasmid 140 MDa was more frequently present in E. coli strains isolated from faeces of patients (in 76.09%) than in strains from healthy subjects (in 23%). The strains circulating in the healthy population were in the majority avirulent.
Assuntos
Infecções por Escherichia coli/microbiologia , Escherichia coli/patogenicidade , Animais , Bioensaio , Bulgária/epidemiologia , Estudos de Casos e Controles , Tchecoslováquia/epidemiologia , Disenteria Bacilar/microbiologia , Escherichia coli/classificação , Escherichia coli/genética , Escherichia coli/isolamento & purificação , Infecções por Escherichia coli/epidemiologia , Cobaias , Células HeLa/microbiologia , Humanos , Plasmídeos/genética , Plasmídeos/isolamento & purificação , Sorotipagem , VirulênciaRESUMO
Escherichia coli 0164 is the most prevalent serotype among the enteroinvasive E. coli in Bulgaria and is annually isolated in sporadic, as well in epidemic cases. We studied 243 strains of this serotype, isolated in different regions of the country over the period 1954-1988. The plasmid analysis performed revealed that the presence of large plasmid DNA with molecular size of 140 MDa was related to the virulence of the strains, assessed by the test of SERENY. The absence of this plasmid or its deletion led to the loss of virulence. In 92% of the strains two small plasmids were demonstrated with molecular size of 6.0 MDa and 4.8 MDa, which appeared to be serotype-specific. On the basis of the plasmid content of the strains, 7 plasmid profiles were differentiated. The stability of the plasmid profile within a given epidemic focus was confirmed.
Assuntos
Escherichia coli/classificação , Plasmídeos , Escherichia coli/genética , Escherichia coli/patogenicidade , Infecções por Escherichia coli/microbiologia , Humanos , Peso Molecular , SorotipagemRESUMO
The incorporation of labelled precursors of DNA, RNA and proteins in F. cells infected with Coxsackie B4 virus has been traced both in the presence and absence of total histone from nucleated erythrocytes during the infectious process. In comparison with the virus infection alone, the exogenous histone supressed the incorporation of 3H-thymidine in early hours and the incorporation of 3H-uridine and 14C-leucine in the 9th hour after virus infection. The established repression of the incorporation of the labelled precurssors for RNA and proteins correlates with a drop in the order of 90 to 99% in the yield of infectious virus.
