Hippurate hydrolysis tests performed on the serotype reference strains of the serotyping scheme based on thermostable antigens under development for Campylobacter jejuni showed that 42 strains were Campylobacter jejuni and 17 were Campylobacter coli. Moreover, only four (0.2%) of 2025 hippurate positive Campylobacter jejuni isolates reacted in Campylobacter coli antisera and 12 (4.3%) of the 282 Campylobacter coli reacted in Campylobacter jejuni antisera. Evidently each species has its own array of antigenic specificities. Separate schemes for serotyping Campylobacter jejuni and Campylobacter coli are advocated.

Some strains of Escherichia coli produce a protein which is cytotoxic for Vero cell and HeLa cell monolayers. This toxin is very similar to the toxin of Shigella dysenteriae 1 and has been named verotoxin or E. coli Shiga-like toxin. It has been shown that toxin conversion is due to a group of bacteriophages, one of which has been designated H-19B. In this study we report hybridization experiments showing that part of the H-19B genome is homologous to phage lambda. We have cloned a 1.7-kilobase BalI-BglII fragment from the genome of H-19B into pUC18. The recombinant plasmid confers the ability to produce high levels of Shiga-like toxin on transformed E. coli cells. We demonstrate using an in vitro transcription/translation system that the cloned fragment specifies the two verotoxin subunit peptides which have masses of 31 and 5.5 kilodaltons. The identity of peptides was confirmed by immunoprecipitation with verotoxin antiserum and protein A-Sepharose beads.

Fifty Campylobacterjejuni isolates, including 29 from humans associated with an outbreak of enteritis, 20 from cattle, and 1 from a milk source, were serotyped on the basis of extractable thermostable antigens and examined by bacterial chromosomal restriction endonuclease digest analysis. Serotyping showed specific differences between the human isolates and the milk isolates, but each of these generally, although not consistently, reacted with 4 of the 42 C. jejuni typing antisera. Restriction patterns of all of the human isolates and some of the cattle isolates were indistinguishable, confirming the suspected link between the cattle and the human outbreak. The single milk isolate had a restriction pattern unlike those of the human isolates, and therefore its involvement in the transmission of infection from the cattle to the humans could not be confirmed.

Summary. During a one-year period, 258 isolates of Campylobacter jejuni and C. coli were obtained from children with gastroenteritis or bacteraemia at the Red Cross Children's Hospital, Cape Town, South Africa. These isolates were biotyped by hippurate hydrolysis, H2S production and tolerance to 2,3,5-triphenyltetrazolium chloride (TTC). Our study indicated that 95.4% of the isolates were C. jejuni biotype 1, 1.5% were,C. jejuni biotype 2 and 3.1% were C. coli; 70% of the isolates were resistant to TTC. Serotyping on the basis of soluble, thermostable antigens detected by a passivehaemagglutination technique revealed that 79% of the Cape Town isolates were typable and that the most common serotypes, in order, were: 4, 2, 12, 23/36 and 19, together comprising 25% of the isolates. About 37% of the typable isolates belonged to nine serotypes. The finding that 21% of the isolates were non-typable suggests the existence of antigenic specificities different from those defined by the 60 antisera in current use.