Fimbriation, surface hydrophobicity and serum resistance in uropathogenic strains of Escherichia coli.

A total of 80 Escherichia coli strains were examined for expression of P-fimbriae, mannose-sensitive haemagglutination (MSHA) and mannose-resistant haemagglutination (MRHA) of human group A erythrocytes and guinea pig erythrocytes, cell surface hydrophobicity and resistance to serum bactericidal activity. Isolates were obtained from urine of children and adults, either with acute pyelonephritis (n = 15 and n 12) or lower urinary tract infection (UTI) (n = 30 and n = 23, respectively). Results obtained showed that, in E. coli strains isolated both from children and adults with lower UTI, significant differences were not found concerning the incidence of P-fimbriae, cell surface hydrophobicity and serum resistance. In pyelonephritogenic E. coli isolated from children and adults, the incidence of P-fimbriae and cell surface hydrophobicity was associated more frequently with the former (87% vs. 42% and 100% vs. 67%, P < 0.05), while serum resistance was associated with the latter (47% vs. 67%, P < 0.05).

Virulence-associated factors in Escherichia coli strains isolated from children with urinary tract infections.

One hundred and sixty-eight strains of Escherichia coli were isolated from cases of pyelonephritis (24) and lower urinary tract infections (UTI) (144) from hospitalised and outpatient children up to 2 years old. These strains were investigated for the expression of P fimbriae (PF), mannose-resistant and mannose-sensitive haemagglutination, cell-surface hydrophobicity, serum resistance and the production of alpha-haemolysin (AH), colicins and aerobactin. PF, AH, aerobactin production and serum resistance were significantly more frequent amongst strains expressing mannose-resistant haemagglutination. PF and AH production was significantly more frequent in pyelonephritogenic strains than in lower UTI strains. Serotypes O6 and O112 were isolated most frequently and plasmids were found in the majority of strains tested.

Characteristics of Pseudomonas aeruginosa strains isolated from urinary tract infections.

Thirty-three uropathogenic strains of Pseudomonas aeruginosa were investigated for hemolytic activity in both bacterial broth culture filtrates and isolate lyzates, resistance to bactericidal activity of fresh human serum, resistance to six antibiotics and plasmid DNA profile. Twenty-four of the 33 (73%) bacterial filtrates showed lysis of rabbit erythrocytes, as did the three after guinea-pig erythrocyte treatment. Twelve of 33 isolate lysates showed in parallel lysis of both types of erythrocytes used. Serum resistance was found in 17 (52%) isolates, intermediate resistance in 15 (45 %) isolates and only one isolate showed serum sensitivity. Resistance to antibiotics was detected as follows (in %): tetracycline 94, kanamycin 79, chloramphenicol 76, septrin 73, ampicillin 64, streptomycin 45, gentamicin 18. None of the isolates investigated showed resistance to colistine. With the exception of one isolate, plasmid DNA was detected in all P. aeruginosa strains.

[Verotoxin as an important factor in the virulence of E. coli strains]. / Verotoxín ako významný faktor virulencie kmenov E. coli.

Verotoxin as a factor of virulence of E. coli strains is involved in the pathogenesis of hemorrhagic colitis, hemolytic-uremic syndrome and thrombotic thrombocytopenic purpura. The most frequent producers of verocytotoxin are E. coli O157:H7 and O157:H-, yet further 57 E. coli serotypes producing verotoxin have been described. The occurrence rate of verocytotoxigenic strains of E. coli is increasing worldwide and should be a matter of concern also in our conditions. (Ref. 56.)

[Sorbitol-negative E. coli 016 in a 10-year-old child diagnosed with hemolytic-uremic syndrome and in his asymptomatic father]. / Sorbitol-negatívne E. coli 016 u desat'rocného diet'at'a s diagnózou hemolyticko-uremický syndróm a u jeho asymptomatického otca.

In Escherichia coli strains isolated from faeces and smears from the rectum in haemolytic-uraemic syndrome of a child and healthy relatives the authors assessed the biochemical activity, antigenic characteristic, sensitivity to twelve antimicrobial substances and factors of virulence. Sorbitol negative strains were isolated from the ill child and his father. The strains belonged into serogroup 016. The remaining strains were sorbitol positive. They belonged into serogroups 02, 012 and 019. Nineteen sorbitol negative strains of E. coli from the sick child caused mannose sensitive agglutination of chicken and guinea pig erythrocytes, they produced colicin V and aerobactin. Except for one strain they were serum resistant. Fourteen strains induced the oedema on the foot of mice and eleven produced a lethal effect in mice. Except for three ampicillin resistant strains the remaining were sensitive to the examined antibacterial substances. Two sorbitol negative strains of E. coli isolated from the asymptomatic father produced aerobactin and one strain was serum resistant.

Enterohaemolysin production in Escherichia coli strains.

Enterohaemolysin production was found in 11 (20.3%) out of 54 Escherichia coli strains isolated from stools of infants with dyspepsia and in 3 (2.3%) out of 130 E. coli strains isolated from urinary tract infections. Enterohaemolysin producing E. coli strains isolated from stools belonged to O groups 25 and 111 and the strains from urine to O groups 1 and 15. None of the enterohaemolysin-producing strains isolated from dyspepsia was shown to cause any damage on Vero cells.

[Virulence factors in strains of Escherichia coli isolated in urinary tract infections]. / Faktory virulencie u kmenov Escherichia coli izolovaných pri mocových infekciách.

In 21 strains of E. coli isolated from patients with cystitis and asymptomatic bacteriuria the authors assessed the group, mannososensitive and mannoresistant agglutination of human, bovine, chick, guinea pig, sheep and pig erythrocytes, the production of haemolysis, colicins, aerobactin, the capacity of strains to induce oedema on mouse paws, the lethal effect in mice, the resistance to tetracycline, streptomycin, chloramphenicol, kanamycin, ampicillin and sulfamethoxidine, the transmission of resistance and sensitivity of strains to the action of fresh human serum. In ten strains the authors recorded also the production of haemolysin and the lethality for mice, in four strains the production of colicin V. production of aerobactin and serum resistance. In three strains the aerobactin production was recorded concurrently with the haemolysin production. In none of the samples P. fimbriae were found.

Killing of alpha-haemolytic and non-haemolytic Escherichia coli strains in human serum and polymorphonuclear leucocytes.

The role of alpha-haemolysin (AH) in the resistance of Escherichia coli strains, isolated from patients with extra-intestinal diseases or diarrhoea, to the bactericidal activity of human serum and intracellular killing in polymorphonuclear leucocytes (PMNL) was investigated in vitro. Sets of alpha-haemolytic and non-haemolytic E. coli strains and sets of isogenic E. coli strains, which included wild-type alpha-haemolytic strains and derived strains with a reduced production of AH, were used. Compared with non-haemolytic strains, alpha-haemolytic strains were significantly more resistant to the bactericidal activity of 10% and 100% human serum and to intracellular killing in PMNL. Higher resistance to serum killing and to intracellular killing in PMNL was also found in wild-type alpha-haemolytic E. coli than in isogenic bacteria with reduced production of AH. These results provide evidence that production of AH in E. coli strains counteracts both the bactericidal activity of serum and intracellular killing in PMNL.

[New findings on alpha-hemolytic strains of E. coli in urinary tract infections. II. Antigen structure, resistance, production of colicins and siderophores]. / Novsie poznatky o alfahemolytických kmenoch E. coli pri mocových infekciách. II. Antigénová struktúra, rezistencia, produkcia kolicínov a sideroforov.

Alphahaemolytic uropathogenic strains of E. coli (UPEC) belong mostly into the serogroup 04, 06, 018 and 075. UPEC are resistant against antibacterial substances and against the bactericide action of serum. Properties which condition the virulence of these strains are also colicin and siderophore production.

[New findings on alpha-hemolytic strains of E. coli in urinary tract infections. I. alpha-hemolysin and adhesins]. / Novsie poznatky o alfahemolytických kmenoch E. coli pri mocových infekciách. I. Alfahemolyzín a adhezíny.

Alphahaemolysin (AH) is one of the important factors of virulence of E. coli strains in urinary infections. The synthesis and secretion of AH is coded by four HLA genes which in the majority of strains are located on the chromosome. Alphahaemolytic strains possess fimbrial and non-fimbrial adhesins.

[Alpha-hemolytic strains of Escherichia coli isolated in urinary tract infections in small children]. / Alfahemolytické kmene Escherichia coli izolované pri mocových infekciách malých detí.

The authors focused attention on testing of biological properties of alpha-haemolytic strains of E. coli in infections of the urinary pathways in children and on the antibody response against alpha-haemolysin. The strains belonged into serogroups 02, 04, 06, 018, 075, 0112. The majority of strains had fimrial adhesins, i.e. P fimbriae, or fimbriae type 1. Alpha-haemolysin one of the factors of UPEC virulence induces anti-alphahaemolysin formation in serum (ANTI AH). Titres of ANTI AH in sera of children with acute uroinfection were from 1:32 to 1:1024. Lower titres were recorded in infections of the lower urinary pathways higher ones in renal infections, whereby the dynamics of ANTI AH titres depend on the development of the disease.

[Characteristics of E. coli strains isolated in infantile diarrhea]. / Vlastnosti kmenov E. coli izolovaných pri hnackách dojciat.

In a group of 50 strains of E. coli isolated from infants hospitalized on account of diarrhoea the authors investigated, based on the phenotypic manifestation and in a selected number of strains also genotypic factors of virulence: fimbrial adhesins, aerobactin, haemolysins, colicins, toxic and lethal action in mice, seroresistence and resistance against tetracycline, streptomycin, chloramphenicol, kanamycin, ampicillin and sulfamethoxidine. All strains had one to eight factors of virulence. The presence of plasmid DNA was confirmed in 14 of 16 tested strains. From this the authors conclude that the investigated virulence factors were in the majority coded plasmids.

Response of Escherichia coli strains carrying plasmid(s) and their plasmidless derivatives to bactericidal activity of human serum and polymorphonuclear leukocytes.

Ten virulence plasmid(s) and antibiotic resistance plasmid(s) carrying Escherichia coli strains isolated from stool of infants with diarrhoea and their plasmidless derivatives were examined for response to bactericidal activity of human serum and intracellular killing of polymorphonuclear leukocytes (PMN). Plasmid(s) carrying isolates exhibited a significantly higher resistance to serum and phagocytosis.

[Personal experience in testing for E. coli enterotoxigenicity]. / Nase skúsenosti z testovania enterotoxinogenity u kmenov E. coli.

When testing the production of the thermolabile enterotoxin by strains of E. coli, using six different methods, the highest positivity (100%) was recorded when using the modified test of oedema on mouse paws and the lowest one (5%) when using the Biken test. The strains were isolated from diarrhoeal infections in young children.

Partial purification of alpha-hemolysin in Escherichia coli.

The present paper describes isolation and purification of alpha-hemolysin of Escherichia coli. The optimum production medium was found to be the Todd-Hewitt broth. Out of thirteen fractions obtained after separation on Sephadex G-200, two fractions possessed the highest relative specific activity.

[Killing of seroresistant plasmid bearing E. coli strains in polymorphonuclear leukocytes]. / Usmrcovanie sérorezistentných kmenov E. coli vybavených plazmidmi v polymorfonukleárnych leukocytoch.

Killing of 61 seroresistant E. coli strains equipped with virulence plasmids (F, Ent, Hly, Col) and resistance plasmids (R) in polymorphonuclear leukocytes (PMNL) of healthy donors was determined by the cultivation plate and fluorescence methods of phagocytosis. Killing of the control E. coli strain K12 which does not possess any plasmids was studied by the fluorescent method. Compared to the fluorescent method, the cultivation plate method yielded a significantly higher killing rate of the bacteria after opsonization by 5% (p less than 0.05) and concentrated serum (p less than 0.001). Compared to the control E. coli strain K12, the killing rate of seroresistant E. coli strains in PMNL of healthy donors was significantly lower (p less than 0.001).

[New findings on enteroinvasive strains of E. coli]. / Novsie poznatky o enteroinvazívnych kmenoch E. coli.

The group of enteroinvasive strains of E. coli (EIEC) comprises at present eleven serogroups. Diarrhoeal diseases caused by EIEC strains are found sporadically or epidemically. It was found that the pathogenicity of EIEC strains is coded in plasmids. So far the plasmid was proved in serogroups 028 a, c, 029, 0124 and 0143. The incidence of EIEC strains is recorded also in the CSSR.

[Evaluation of phagocytosis of alpha hemolytic strains of Escherichia coli using the fluorescence method]. / Hodnotenie fagocytózy alfa hemolytických kmenov Escherichia coli fluorescencnou metódou.

The authors investigated phagocytosis in 37 alpha haemolytic strains of E. coli by the fluorescent method, after opsonization of bacteria with 5% and concentrated human serum. The strains were isolated from infants with gastrointestinal and extraintestinal infections and belonged to eleven serogroups. During opsonization of the strain with concentrated serum, as compared with opsonization of strains with 5% serum, higher rates of killing were recorded. As compared with a control strain of E. coli K12 after opsonization with concentrated serum in the examined strains the value of killing was on average by 20% lower. Differences in the killing of examined strains were recorded also within a single serogroup which may be ascribed to the different provision of strains with plasmids.

[Escherichia coli in diarrheal disease in young children]. / Escherichia coli pri hnackových ochoreniach malých detí.

The authors describe a lower incidence of enteropathogenetic serogroups of Escherichia coli (EPEC) in 1981-1987. Of 85 EPEC strains tested for the presence of factors of virulence (fimbrim, enterotoxins, haemolysins, colicins) and factors of virulence against six antimicrobial substances (tetracycline, streptomycin, chloramphenicol, kanamycin, ampicillin, sulfamethoxidine) only three strains did not possess any of the mentioned factors. The authors draw attention to other pathogenetically important groups of E. coli in the aetiology of diarrhoea in young children.