A total of 134 enterotoxigenicEscherichia coli (ETEC) of serogroups O25, O27, O148, and O159 were tested in the enzyme-linked immunosorbent assays for the colonization factor antigens I (CFA/I), CFA/II (coli surface antigens CS1, 2 and 3) and putative colonization factor (PCF) 8775 (CS4, 5 and 6). CS6 was detected without CS4 or CS5 in 94% of the strains of serogroup O25, 86% of strains of serogroup O27, 87% of strains of serogroup O148, and 29% of strains of serogroup, O159. The frequency with which CS6 occurs in ETEC of common serotypes without the antigens CS4 or CS5 suggests that it might be a colonization factor.

OBJECTIVE: To report on the prevalence of isolates with ciprofloxacin resistance in non-typhoidal salmonellas from humans in England and Wales in 1997. METHODS: All non-typhoidal salmonellas referred to the Laboratory of Enteric Pathogens in 1997 were screened for resistance to ciprofloxacin at 0.125 and 1.0 mg/L and nalidixic acid at 16 mg/L, and results were compared to those for 1994. Full minimal inhibitory concentrations (MICs) of these antimicrobials were also determined for a selection of isolates resistant to ciprofloxacin at 0.125 mg/L but sensitive at 1.0 mg/L, and for all isolates resistant at 1.0 mg/L. RESULTS: Since 1994 there have been increases in the occurrence of resistance to ciprofloxacin (MICs: 0.25-1.0 mg/L) in Salmonella enterica serotypes Enteritidis, Typhimurium, Virchow and Hadar. Of particular importance have been increases in the occurrence of resistance in multiresistant S. Typhimurium DT 104, and also in S. virchow, a serotype with a propensity for causing extraintestinal infections in humans. High-level resistance (MIC >/=2.0 mg/L) was uncommon and was identified in only a few strains, all from patients with a history of recent foreign travel. CONCLUSIONS: There is a strong temporal association between increases in the occurrence of ciprofloxacin resistance in Salmonella serotypes Typhimurium, Virchow and Hadar from humans in England and Wales and with the licensing for use in food animals in the UK of the related fluoroquinolone antibiotic enrofloxacin; in contrast, for S. enteritidis ciprofloxacin resistance was most common in a phage type associated with foreign travel. It is hoped that recent recommendations for the use of fluoroquinolone antimicrobials in food animals in the UK will result in a reduction in the occurrence of resistance to ciprofloxacin in zoonotic salmonellas causing infections in humans.

Growth of strains of Salmonella enteritidis and Salmonella pullorum on Hektoen agar has been reported to influence the expression of long-chain lipopolysaccharide and motility respectively. In this study we used a panel of strains of S. enteritidis and S. pullorum to investigate these phenomena. Culture on Hektoen agar did not cause rough strains of S. enteritidis to express long-chain lipopolysaccharide or strains of S. pullorum to become motile. It was concluded that growth of strains of S. enteritidis and S. pullorum on Hektoen agar would not normally affect the expression of somatic or flagellar antigens, and would not influence the interpretation of the Kauffman-White typing scheme.

OBJECTIVE: To determine the prevalence of enteroaggregative Escherichia coli (EAggEC) in African diarrheal children in Lwiro, Congo, to characterize EAggEC isolates by possible genotypic and phenotypic markers, and to evaluate the EAggEC probe pCVD432 in identifying EAggEC. METHODS: The Hep-2 cell adhesion assay and colony-blot hybridization assays were carried out for the identification of EAggEC. O:H serotyping, biotyping, antibiogram and plasmid-profile analysis were done. To detect the E. coli LT and ST, ELISA tests were used and, for VT, a vero cell assay was used. RESULTS: EAggEC strains were isolated from 56 out of 115 diarrheal children (48.7%): the organism was present alone and presumed to cause diarrhea in 22 (19.1%) cases. The rest of the cases were associated with two or more diarrheagenic E. coli strains. EAggEC strains were isolated from 25% of total diarrheal children (first day of isolation) and 8.86% of age-matched healthy individuals (p<0.03). This isolation rate was significantly higher than the one found for other diarrheagenic E. coli strains. In parallel, we evaluated the sensitivity and specificity of EAggEC probe pCVD432, and found that it had 56% sensitivity with 100% specificity compared with the Hep-2 cell test. EAggEC isolates were characterized by serotyping, biotyping, antibiotic resistance pattern, plasmid profiling and toxin production analysis. They did not produce any one of these classical toxins and nor did they relate to any particular serotypes. Plasmid analysis of the 79 EAggEC isolates (n=315) showed seven different profiles. Ten resistance patterns were identified and 34 strains were sensitive to all drugs. There was no association between plasmid profiles and antibiotic resistance patterns. All 16 classical E. coli biotypes were found in this small EAggEC population. CONCLUSIONS: EAggEC has been emerging as a cause of childhood diarrhea in African children in Congo. From the accumulated data it was found that there is a great heterogeneity in EAggEC populations.

A type of in vivo phenotype of Campylobacter jejuni was obtained by maintaining bacteria in the peritoneal cavities of chickens for one week. These bacteria, which had not been subcultured on laboratory media, were used to prepare outer membranes for comparison with C. jejuni grown in vitro. Flagella with subunits of 65 kDa and a single porin with a protein subunit of 49 kDa were expressed constitutively; however, outer membrane proteins of 55, 35 and 20 kDa, and intermediate-chain lipopolysaccharide were only expressed by bacteria maintained in chickens.

The pH of the environment influenced the expression of outer membrane proteins by S. enteritidis PT4 growing in broth. Growth in broth at pH 5 to 7 resulted in variation in expression of outer membrane proteins of 18 to 22 kDa. Bacteria became acid-fixed and non-viable following prolonged incubation in broth with a pH below 5, and expression of flagella was repressed.

We report primers and conditions for the generation by PCR of a probe for the DNA insertion element IS200. This probe was shown to be suitable for genotypic subtyping within a single phage type of Salmonella typhimurium. A collection of isolates of DT204c, a phage type implicated in the spread of multiple drug resistance in bovine animals and to man, was analyzed. Three IS200 profiles, corresponding to related chromosomal genotypes were characterized in DT204c. Molecular discrimination within a single phage type of S. typhimurium has general significance for genotypic typing, and for the definition of epidemiological clonality in Salmonella.

Blood group P1 expression was scored by direct agglutination in 32 patients who had previously developed post-enteropathic haemolytic uraemic syndrome (HUS). Sixty-six children of similar ages undergoing venepuncture for other renal disorders acted as controls. The expression of P1 in controls was that expected from the normal caucasian population, 23% being negative. By contrast, there was an excess of HUS patients with weak or absent expression of P1 (χ2 for linear trend 5.45,P<0.02), and this was particularly evident in those with a poor outcome. Verotoxin (VT), which is associated with HUS, requires the terminal disaccharide of the P1 antigen to bind to cells, and after internalization disrupts the transcription of ribonucleic acid. Mature erythrocytes do not synthesize protein and may be toxin resistant. We postulate that strong expression of P1 antigen may promote the binding of VT to red cells and thus reduce the dose to vulnerable nucleated cleated endothelial cells. P1 positivity may be protective, and P1 negativity a risk factor in HUS.

mutants, aswell asenterotoxigenic butCS-negative strains, induced diarrhea inonly a few cases.Mutants carrying CS6alone colonized theintestine equally as well as strains carrying CS4-CS6 or CS5-CS6did,whereas CS-negative mutants were excreted inthestool fora significantly shorter period. Rabbits previously infected withmutantscarrying CS6alone or CS6incombination withCS4or CS5 developed diarrhea with asignificantly lower frequency after reinfection with a normally highly diarrheagenic doseofenterotoxigenic CS4-CS6-positive E.coli bacteria thandidanimals immunized withcorresponding CS-negative mutants. Fecal excretion oftherechallenge strain was alsoofconsiderably shorter duration than thatobserved after initial infection withcorresponding strains in27ofthe30animals (90%)immunized with strains carrying CS6alone orincombination withCS4orCS5.Suchreduced shedding ofthechallenge strain was only seenina fewrabbits (3of12)initially infected withCS-negative bacteria. Theseresults suggest that theCS6component ofPCF8775 isa colonization factor inrabbits andthatitisalsocapable ofinducing protective immunity.

Vero cytotoxin (VT) producing strains of Escherichia coli (VTEC), including isolates from cases of haemolytic uraemic syndrome and infantile diarrhoea, were used to determine the effect of iron availability on the production of intra- and extracellular VT, with particular interest in elevating toxin production by low-level toxin producing VTEC. Culturing bacteria under iron restriction resulted in growth retardation and a decrease in the production of VT. For the routine detection of both high- and low-level VT-producing E. coli, there was no advantage to be gained by growing bacteria under iron restriction or using disrupted bacterial cell preparations; on the contrary, testing culture supernatants from bacteria grown in iron-replete media for approximately 14 h proved to be the most sensitive and accurate method for detecting VT and the resultant identification of VTEC.

Molecular cloning from a plasmid encoding colonization factor antigen I (CFA/I) and heat-stable enterotoxin isolated two regions, 1 and 2, that are required for the production of CFA/I fimbriae. The level of CFA/I synthesis measured by ELISA was similar in an Escherichia coli K12 strain carrying regions 1 and 2 cloned separately on compatible plasmid vectors to that in the same strain containing the parental plasmid. The structural gene for the CFA/I fimbrial subunit was within region 1. This region directed production in E. coli minicells of at least six independent polypeptides, of which the fimbrial subunit and at least three others appeared to be synthesized as precursor molecules that underwent processing. Cloned DNA containing CFA/I region 2 specified three polypeptides in minicells. Attempts to reduce the size of the cloned region 1 resulted in a derivative plasmid that carried the CFA/I structural gene but did not complement a region-2 recombinant plasmid to restore production of CFA/I fimbriae.

The ability of certain Escherichia coli strains to produce enterotoxin is determined by transmissible plasmids. It is therefore possible that any E. coli strain might be able to acquire such a plasmid and that the correlation between enterotoxigenicity and serotype might be random. However, recent studies show that the enterotoxigenic strains so far describe belong to a restricted range of serotypes. Enterotoxigenic strains of E. coli O6.H16 and E. coli O148.H28 have been associated with outbreaks of diarrhoea in several countries, therefor strains of E. coli belonging to these serotypes were selected for further study. Twenty-three strains of E. coli O6.H16 and 14 strains of E. coli O148.H28 were examined; 20 strains of E. coli O6.H16 and all 14 strains of E. coli O148.H28 were enterotoxigenic but strains of E. coli O6 wit flagellar antigens other than H16 and strains of E. coli O148 wit flagellar antigens other than H28 were not enterotoxigenic. The examination of single colony subcultures derived from the E. coli O6.H16 strains showed that in some strains loss of enterotoxigenicity had occurred in a proportional of colonies.