The prevalence of Shiga toxin-producing Escherichia coli in domestic animals and food in Serbia.

Faecal samples of 2660 domestic animals from 116 farms and 956 samples of food were examined for the presence of Shiga toxin-producing Escherichia coli (STEC). STEC was recovered from 126 (15.3%) cattle, 135 (11.3%) pigs, 135 (66.8%) sheep, 31 (73.8%) goats, 4 (1%) chicken, and 15 (1.6%) food samples. Of all STEC isolates, 21.5, 25.8 and 15% produced enterohaemolysin, alpha-haemolysin, and aerobactin respectively, 1.6% displayed localized adherence (LA) to HEp-2 cells, 27.6% were sorbitol negative, and 30% were resistant to antibiotics. Only 14 (3.1%) of the STEC isolates belonged to human infection-associated serogroups (O26, O55, O111, O128 and 0157), designated as enterohaemorrhagic E. coil (EHEC). This study revealed that STEC are prevalent in domestic animals, and to a lesser extent in food of animal origin in Serbia, but the absence of a EHEC phenotypic profile (characteristic serogroup, LA, enterohaemolysin production) in most animal STEC strains may explain the low incidence of human STEC infection in this part of the world.

[Reliability of plasmid profile analysis in the identification of epidemic strains of bacteria causing an outbreak of intestinal infections]. / Pouzdanost metode analize plazmidskog profila u identifikaciji epidemijskih sojeva bakterija uzrocnika epidemija crevnih zaraznih bolesti.

The aim of the study was to determine the plasmid profile of isolates originated from the outbreaks of gastrointestinal tract infection in the attempt to identify the outbreak strains. Plasmid profile analysis was performed on 163 isolates; 82 isolates originated from foodborne outbreakes and 81 isolates originated from waterborne outbreakes or outbreakes spread by contact. Outbreak strain was identified in 1 (10%) of 10 foodborne outbreakes and in 7 (70%) of 10 waterborne outbreakes or outbreakes spread by contact. According to the obtained results, the method of plasmid profile analysis was more reliable in the investigation of outbreaks of gastrointestinal tract infection spread by water or contact compared to the outbreakes spread by food.

[Reliabilty of the antibiogram and plasmid profile in detection of epidemic strains of Shigella sonnei]. / Pouzdanost primene antibiograma i plazmidskog profila u prepoznavanju epidemijskih sojeva Shigellae sonnei.

The aim of the study was to investigate and compare the type of resistance to antibiotics and plasmid profile of Shigellae sonnei isolated at epidemics of bacillary dysentery to determine which method was most reliable in the identification of epidemic strains of that bacteria. It was investigated 130 isolates of Sh. sonnei isolated from the stools of patients in 14 epidemics of bacillary dysentery in Yugoslav Army and citizens in period from 1987 to 1993 year. On the basis of identity of studied features of all isolates originated from one epidemic, epidemic strains of Sh. sonnei could be identified in 10 (71.4%) of 14 studied epidemics by means of plasmid profile, and in 8 (57.1%) epidemics by means of determination of resistance type to antibiotics. According to that, the method of plasmid profile analysis is more reliable in identification of Sh. sonnei epidemic strains compared to the method of determination of resistance type to antibiotics.

Enteroaggregative Escherichia coli associated with an outbreak of diarrhoea in a neonatal nursery ward.

Over a 9-day period in February 1995, 16 newborn babies (age range 2-11 days) and 3 infants (24, 47 and 180 days of age) in a neonatal nursery ward developed diarrhoea accompanied by pyrexia and weight loss. Known enteropathogens were not detected in their stools but Escherichia coli displaying aggregative adherence to HEp-2 cells (enteroaggregative E. coli) were found in 12 (63%) ill infants and in none of 5 well neonates (P = 0.02). The illness lasted 3-9 days (mean 5.2) in 16 babies, whereas in 3 neonates it showed a protracted course of 18-20 days. The source of infection and the mode of transmission remained unclear. The outbreak isolates manifested properties common in this new group of diarrhoeagenic E. coli: mannose-resistant haemagglutination, haemolysis on blood agar, and clump formation in liquid culture medium. They belonged to the O4 E. coli serogroup and expressed multiple antibiotic resistance.

Infrequent finding of verotoxin-producing Escherichia coli in diarrheal stools in Belgrade, Serbia.

Out of 2,638 patients, with acute diarrhea, verotoxin-producing Escherichia coli (VTEC) was isolated from the stools of 8 (0.3%). There was no visible blood in their stools and none of them developed other syndromes associated with VTEC infection. None of the isolated VTEC agglutinated with O157 E. coli antiserum, while only 3 strains hybridized with the DNA probe CVD 419, designed to detect VTEC. The data obtained suggest that VTEC is not an important causative agent of acute diarrhea in Belgrade.

[An epidemic of acute enterocolitis caused by enterotoxigenic Escherichia coli]. / Epidemija akutnog enterokolitisa izazvana enterotoksigenom eserihijom koli.

In an epidemic of enterocolitis on a military ship which lasted two days, 13 (54%) out of 24 soldiers became ill. The clinical picture was mild with predomination of diarrhoea and abdominal pain, and the troubles in all ill persons ended within 48 hours with administration of symptomatic therapy. Since routinely examined causative agents of infectious diseases were not detected, detailed examination of 13 Escherichia coli strains isolated from stools of the ill persons as well as 8 strains from stools of healthy but exposed soldiers, revealed that 7 of them produced enterotoxins; 5 strains produced heat-labile (LT) and heat-stabile (ST) enterotoxins, and 2 strains ST only. Enterotoxigenic strains were isolated from stools of 5 (38.5%) ill persons and 2 (25%) healthy persons. According to epidemiological investigations, infection was transmitted by secondary contaminated food due to its mishandling. The presented results prove that enterotoxigenic E. coli play a role as a causative agent in epidemics of acute enterocolitis in adults.

Escherichia coli K-12 ferrous iron uptake mutants are impaired in their ability to colonize the mouse intestine.

The streptomycin-treated mouse colonization model was used to investigate the role of the Fe2+ uptake system (Feo) of Escherichia coli K12 in the colonization of the mouse intestine. Mutants impaired in the uptake of Fe2+ ions were shown to be deficient also in their colonization ability. Both enterochelin-producing and enterochelin-nonproducing Escherichia coli feo mutants were unable to colonize the mouse intestine. These results demonstrated that Fe(II) is an essential source of iron for E. coli grown in the intestine.

The ability of rifampin-resistant Escherichia coli to colonize the mouse intestine is enhanced by the presence of a plasmid-encoded aerobactin-iron(III) uptake system.

Rifampin-resistant Escherichia coli are known to be poor colonizers of the animal intestine. In this report, we show that the colonizing ability of rifampin-resistant E. coli cells is increased dramatically in the presence of the aerobactin-mediated iron(III) uptake system. In contrast, the colonization by nalidixic acid-resistant E. coli does neither depend on the aerobactin-iron(III) nor on the dicitrate-iron(III) uptake system. Likewise, it does not depend on the production of the siderophore enterochelin.

Haemolytic-uraemic syndrome associated with Aeromonas hydrophila enterocolitis.

Haemolytic-uraemic syndrome (HUS) associated with Aeromonas hydrophila enterocolitis is reported in a 23-month-old female infant. The A. hydrophila strain isolated from the patient's stool sample produced cytotoxin against verocells; increasing levels of cytotoxin-neutralizing antibody in the patient's sera were demonstrated, suggesting a recent infection. This report indicates that A. hydrophila should be suspected as a possible cause of HUS, and that this pathogen should be looked for in cases of post-diarrhoeal HUS.

[Preparation of a DNA probe for thermolabile toxin and its use in the identification of enterotoxic Escherichia coli]. / Pravljenje DNK probe za termolabilni toksin i njena primena za identifikaciju enterotoksicnih Escherichia coli.

Enterotoxic Escherichia coli (ETEC) having a gene for thermolabile toxin were identified by the hybridization technique. HindIII-SmaI fragment with 423 basic pairs (dp) including subunit portions A and B of the gene for thermolabile toxin (elt) was used as the DNA probe.

Lack of association of Escherichia coli exhibiting both mannose-resistant haemagglutination and diffuse adherence to HEp-2 cells with acute diarrhoea in children.

Stool specimens from 631 children with acute diarrhoea and from 277 healthy controls were tested for the presence of non-enteropathogenic, non-enterotoxigenic Escherichia coli strains which mediated mannose-resistant haemagglutination of human erythrocytes (MRHA+). Fifty-nine (34.9%) of 169 isolated MRHA+ strains but none of 210 MRHA- strains exhibited diffuse adherence (DA+) to HEp-2 cells. DA+ strains were found in 37 (5.9%) children with diarrhoea and in 22 (7.9%) controls. MRHA+/DA+ strains in comparison to MRHA+/DA- strains significantly less frequently expressed P fimbriae (10.7 vs. 73.6%), haemolysin production (12.5 vs. 63.2%), and MRHA of other species erythrocytes (21.4 vs. 84%). These data demonstrate that E. coli which exhibit the diffuse pattern of adherence to HEp-2 cells also cause MRHA of human erythrocytes. Since these strains were found with similar frequencies in children with and without diarrhoea it seems that DA is not a marker of enteropathogenicity of E. coli.

The association of enterotoxigenic and enteropathogenic Escherichia coli and other enteric pathogens with childhood diarrhoea in Yugoslavia.

The presence of enterotoxigenic and enteropathogenic Escherichia coli (ETEC and EPEC, respectively) was investigated in stool specimens of 1082 preschool children with diarrhoea and in stools of 335 healthy controls in localities in southern Yugoslavia, as well as in 566 children with diarrhoea and in 231 controls living in northern part of the country, during the seasonal peak (August-November) of enteric diseases in 1986. ETEC were found in 114 (10.5%) children with diarrhoea and in 14 (4.2%) controls (P less than 0.001) in the southern part, and in 26 (4.6%) ill children and one (0.4%) well child (P less than 0.005) in the northern part of Yugoslavia. EPEC were isolated from stools of 85 (7.9%) children with diarrhoea and of 14 (4.2%) well children (P less than 0.05) in localities of southern Yugoslavia, and from 22 (3.9%) ill children and from 10 (4.3%) controls in northern Yugoslavia. Nineteen EPEC strains expressed localized adherence to HEp-2 tissue culture cells; all were isolated from stools of ill children. In southern Yugoslavia, where other enteropathogens were sought, the most commonly found agents in ill children were shigellae (17.5%), rotavirus (11.8%), ETEC, and EPEC. Potential pathogens were detected in 44.5% cases of sporadic diarrhoea and in 15.8% controls. This study revealed that ETEC were associated with acute diarrhoeal disease in Yugoslav preschool children. On the other hand, the diagnosis of EPEC-diarrhoea by routine determination of serogroup established the association of these agents with sporadic diarrhoea only in the 0-2 years age categories in all investigated localities. In the less developed southern part of Yugoslavia bacteria were the predominant causative agents of enteric illness during the seasonal peak of this disease.

[Isolation of Shigella boydii serotype 14 with altered biochemical characteristics in a water-borne epidemic of dysentery]. / Izolacija Shigella boydii, serotip 14 izmenjenih biohemijskih osobina u hidricnoj epidemiji dizenterije.

Two water-borne epidemics of bacillary dysentery have been described in a garrison in which the leading causative agent has been shigella boydii, serotype of 14 altered biochemical characteristics isolated for the first time in Yugoslavia. All the isolated strains of this shigella were mannitol negative and they degradated gylocose to acidity and gas already after 24 hours, and arabinose and sorbitol to acidity and gas after 48 hours. The clinical picture of the diseased was characteristic of bacillary dysentery and did not differ from clinical picture of patients in whom other serotypes of shigella were isolated.