The serological relationship between Yersinia enterocolitica O9 and Escherichia coli O157 using sera from patients with yersiniosis and haemolytic uraemic syndrome

Sera from patients with yersiniosis, shown to contain antibodies to Yersinia enterocolitica O9; and sera from patients with haemolytic uraemic syndrome (HUS) caused by Escherichia coli O157, were used to investigate serological cross-reactions between Y. enterocolitica O9 and E. coli O157. Lipopolysaccharide (LPS) was isolated from strains of Y. enterocolitica O9 and E. coli O157 and reacted with sera by immunoblotting and ELISA. Sera from patients with HUS contained antibodies to the LPS of E. coli O157 only; 80% of sera from patients with yersiniosis contained antibodies to the LPS of Y. enterocolitica O9 and E. coli O157. This one-way cross-reaction was also detected using hyperimmune rabbit antisera.

Examination of retail chickens and sausages in Britain for vero cytotoxin-producing Escherichia coli

Samples from chickens and pork sausages were examined for the presence of Vero cytotoxin-producing Escherichia coli by using DNA probes for the Vero cytotoxin genes. Hybridization was detected in 25% of the 184 sausage samples, but none of the chickens was positive. No E. coli O157:H7 strains were isolated, and serotyping showed that the Vero cytotoxin-producing E. coli strains belonged to eight different O serogroups and that six strains had an unidentifiable O antigen.

Surveys of human enterotoxigenic Escherichia coli from three different geographical areas for possible colonization factors

Enterotoxigenic Escherichia coli (ETEC) from Burma, central Africa (Rwanda and Zaire) and Peru, were screened by enzyme-linked immunoassays for the colonization factor antigens (CFAs) and putative colonization factors (PCFs): CFA/I, CFA/II, which consists of three coli surface-associated (CS) antigens, CS1, CS2 and CS3, CFA/III, CFA/IV (CS4, CS5, CS6), CS7, PCFO9, PCFO159. H4, PCFO166, and CS17. The highest proportion of ETEC with identifiable colonization factors (71%) were found in the strains from Burma, which were mainly positive for CFA/I (38%), but strains producing CFA/II (4%), CFA/IV (11%), CS7 (10%), CS17 (4%), PCFO159, H4 (2%) and PCFO166 (2%) were also found. Sixty-nine percent of the ETEC from central Africa were positive for known colonization factors. While CFA/I positive strains were important (12%), a higher number of ETEC producing CFA/IV (33%) and CS17 (24%) were found. Fifty-two percent of the Peruvian strains produced identifiable colonization factors. The largest group of strains produced antigens of the CFA/IV complex (17%), while ETEC producing CFA/II (6%), CFA/III and CS6 (2%), CS7 (6%), PCFO9 (6%), PCFO166 (8%) and CS17 (7%) were also found. These surveys show that there is a considerable variation in the proportions and types of colonization factor found in different geographical areas. From 29 to 48% of the ETEC did not possess an identifiable colonization factor. These were particularly of the LT only producing type. These results have important implications for vaccine formulation.

Extended serogrouping scheme for motile, mesophilic Aeromonas species

A total of 1,255 strains of motile, mesophilic Aeromonas species isolated from clinical and environmental specimens in the United Kingdom and 258 strains isolated in Australia, Brazil, Peru, and the United States were examined by using antisera for serogroups O1 to O44 (R. Sakazaki and T. Shimada, Jpn. J. Med. Sci. 37:247-255, 1984) and for unpublished serogroup O45 (R. Sakazaki). The typeability rate for strains isolated in the United Kingdom was 35%; the strains isolated in other countries had typeability rates of between 14 and 43%. A total of 52 provisional new serogroups were identified, and the strains with unidentified O groups were examined by using antisera for these provisional new serogroups. The typeability rate for strains isolated in the United Kingdom was increased to 66% (70% of smooth strains). The typeability rates were 76% for A. hydrophila and 63% for both A. caviae and A. sobria. The 52 antisera for the provisional new serogroups increased the typeability rate for strains isolated outside the United Kingdom to between 43 and 68%. This extended serogrouping scheme would be of value in determining the importance of Aeromonas strains as human intestinal pathogens and in investigating the pathogenic mechanisms that may be involved in the production of diarrheal disease.

Four new provisional serovars of Shigella

Four bacterial strains are described that possess the biochemical characteristics of Shigella species but do not belong to any of the established Shigella serovars or to any previously described provisional serovar. One strain fermented mannitol, and it is proposed that this be the type strain for a new provisional serovar of Shigella boydii. The remaining strains did not ferment mannitol and belonged to three different serovars. These strains are proposed as type strains for three new provisional serovars of Shigella dysenteriae. All four strains were invasive in a HEp-2 cell tissue culture test, but only one was invasive in the guinea pig eye test and might therefore be expected to cause dysenterylike illness in humans. It is important that the designation of such strains remain provisional until other reference laboratories have had the opportunity to search for additional isolates and the possible pathogenicity of these strains for humans can be further assessed.

Vero cytotoxin production and presence of VT genes in Escherichia coli strains of animal origin

Vero cytotoxin (VT) production has been studied in 34 Escherichia coli strains isolated from animals with enteric diseases. The strains were tested by DNA hybridization with probes for VT1 and VT2 sequences and also in toxin neutralization experiments with specific antisera. Twenty bovine strains, belonging to nine different O serogroups, produced VT1 or VT2 but not both toxins. In contrast, all 14 porcine strains of four different O serogroups produced VT2 only. Six of these porcine strains, belonging to serogroups O138, O139 and O141, were isolated from cases of oedema disease. In general, the porcine isolates produced toxin at a lower level than the bovine strains.

Drug resistance among Escherichia coli strains isolated from cerebrospinal fluid

One hundred and thirty-one strains of Escherichia coli isolated from the cerebrospinal fluid of patients in the United Kingdom were tested for resistance to 13 antimicrobial drugs. Sixty-four strains (49%) were resistant to one or more drugs and 44 (34%) were resistant to three or more drugs. Resistance to ampicillin, sulphonamides, streptomycin and tetracycline occurred most frequently.

Antigenic relationships between the enteroinvasive Escherichia coli O antigens O28ac, O112ac, O124, O136, O143, O144, O152, and O164 and Shigella O antigens

Enteroinvasive Escherichia coli strains have been found in the following O serogroups: O28ac, O112ac, O124, O136, O143, O144, O152, and O164. The biochemical reactions of these enteroinvasive E. coli strains are often similar to those of Shigella strains, and identification may be difficult. The problem of differentiation and identification is further complicated by the sharing of antigenic components. The antigenic relationships between these O antigens and those of all the established and provisional Shigella serovars were examined. O antigen identity was demonstrated between E. coli O124 and Shigella dysenteriae 3 and between E. coli O152 and provisional Shigella serovar 3341:55. Reciprocal relationships were found between E. coli O112ac and S. dysenteriae 2, S. boydii 1, S. boydii 15, between E. coli O136 and S. dysenteriae 3, and between E. coli O164 and S. dysenteriae 3. A one-way relationship was demonstrated between E. coli O136 and S. boydii 1. The remaining enteroinvasive E. coli O serogroups showed no significant antigenic relationships with any Shigella serovar.

Enterotoxigenic and enteroinvasive Escherichia coli strains belonging to a new O group, O167

A new Escherichia coli O group, O167, is described. Its O antigen is related to that of Shigella boydii 3. A total of 29 strains belonging to the new O group were examined. Three strains were determined to be invasive by the Sereny test and by tissue culture tests and were non-enterotoxigenic. All three were nonmotile and failed to decarboxylate lysine. A total of 26 strains were noninvasive. Of these, 25 were motile, 24 decarboxylated lysine, and 19 were enterotoxigenic, 17 producing heat-stable enterotoxin only and 2 producing heat-labile enterotoxin only. This is the first description of the occurrence of enterotoxigenic and enteroinvasive strains in the same E. coli O group.

Antigenic relationships among type strains of Yersinia enterocolitica and those of Escherichia coli, Salmonella spp., and Shigella spp

The antigenic type strains for Yersinia enterocolitica antigens O:1 to O:34 were examined and their antigenic relationships with the type strains of Escherichia coli, Shigella spp., and Salmonella spp. were determined. Y. enterocolitica O:5,27 was antigenically identical to E. coli O97 and Y. enterocolitica O:11 was antigenically identical to E. coli O98.

New provisional serovar of Shigella boydii

Ten bacterial strains are described that give biochemical reactions characteristic of the genus Shigella but do not belong to any of the established or provisional serovars. The strains ferment mannitol and are antigenically indistinguishable. They do not possess any of the group antigens of Shigella flexneri, and it is therefore proposed that they be regarded as members of a new provisional serovar of Shigella boydii. Strain E16553 is designated as the test strain for the new serovar.

Increase in drug resistance among Shigella dysenteriae, Sh flexneri, and Sh boydii

Two thousand three hundred and seventy strains of Shigella dysenteriae, Sh flexneri, and Sh boydii isolated in England and Wales from 1974 to 1978 were tested for resistance to 12 antimicrobial drugs. Eighty per cent of strains were resistant to one or more drugs, with sulphonamide resistance occurring most frequently. Resistance to streptomycin, tetracycline, ampicillin, and chloramphenicol increased during the period, as did the incidence of multiple resistance. Most infections due to Sh dysenteriae, Sh flexneri, and Sh boydii are acquired abroad, and the increasing incidence of drug resistance among these organisms contrasts with the decreasing incidence of resistance among the indigenous Sh sonnei. These findings may indicate the need for better control of antibiotic use, particularly in developing countries.

The occurrence of plasmids carrying genes for both enterotoxin production and drug resistance in Escherichia coli of human origin

Twenty-three of 89 enterotoxigenic strains of Escherichia coli were resistant to one or more antimicrobial agents. Eleven strains transferred resistance directly and five transferred resistance after mobilization. In three cases a resistant recipient was enterotoxigenic. One of these strains contained a conjugative plasmid carrying genes for both drug resistance and enterotoxin production. In the two other strains genes for drug resistance and enterotoxin production were carried on separate co-transferable plasmids.

Isolation of bacteriophages specific for the K1 polysaccharide antigen of Escherichia coli

Five bacteriophage stocks were prepared after enrichment of a sewage sample using Escherichia coli 02:K1:H4 (strain U9/41). The bacteriophages were tested for their ability to lyse 224 strains of E. coli that had been tested for the presence of the K1 antigen by means of an antiserum-agar diffusion technique, using a meningococcus group B antiserum known to detect the E. coli K1 antigen. The standard test strains for E. coli K antigens 2 to 99 were used as control strains. Of the 101 strains found to possess the K1 antigen using the antiserum-agar technique, 93 were lysed by at least one of the bacteriophages, whereas 8 of the 123 strains apparently lacking K1 were lysed by one or more of the bacteriophages. None of the standard test strains for K antigens 2 to 99 was lysed by any of the bacteriophages. The eight strains thought to lack K1 but that were lysed by bacteriophage were re-examined by immunoelectrophoresis, using meningococcus group B antiserum; five of the eight strains gave a precipitin line corresponding to K1. The use of K1-specific bacteriophages offers an inexpensive and easy method for the identification of the K1 antigen.

Incidence of K1 antigen in Escherichia coli isolated from blood and cerebrospinal fluid of patients in the United Kingdom

Altogether 411 cultures of Escherichia coli isolated from blood and 60 from cerebrospinal fluid (CSF) of patients in the United Kingdom were identified biochemically and serologically. They were tested for the presence of K1 antigen by an antiserum-agar method using horse meningococcus group B antiserum and by slide agglutination using E. coli 07.K1.H-antiserum. In total 71 cultures from blood (17%) and 29 from CSF (48%) gave positive results by both methods and were considered to possess the K1 antigen. Among the cultures from patients less than 3 years of age the K1 antigen was found significantly more often in those isolated from CSF (53%) than in those from blood (29%). The K1 antigen was found significantly more frequently in cultures isolated from the blood of patients less than 3 years old (29%) than in those from the blood of older patients (13%). Cultures which gave negative results in the slide agglutination test also gave negative results by the antiserum-agar method but positive results obtained by slide agglutination were not always confirmed using the antiserum-agar technique. Slide agglutination was considered to be valuable for the elimination of K1 negative cultures, but positive results required confirmation using the antiserum-agar method.