Sensitivity and specificity of an enzyme-linked immunosorbent assay using the recombinant DNA-derived Treponema pallidum protein TmpA for serodiagnosis of syphilis and the potential use of TmpA for assessing the effect of antibiotic therapy.

The recombinant DNA-derived Treponema pallidum membrane protein TmpA, purified from Escherichia coli K-12, was used in an enzyme-linked immunosorbent assay (ELISA) to evaluate its suitability in a screening test for syphilis and to monitor the effect of antibiotic treatment. The sensitivity of the TmpA ELISA was 76% for primary syphilis, 100% for secondary syphilis, and 98% for early latent syphilis. All except 1 of 15 serum samples positive for yaws were positive in this test. A specificity of 99.6% was found by testing more than 938 donor samples. The sensitivity and specificity of the TmpA ELISA are comparable to that of the T. pallidum hemagglutination assay, and therefore the test may be useful for the diagnosis of untreated syphilis. After antibiotic treatment, the level of anti-TmpA antibodies in sera of syphilis patients dropped sharply within 1 year. Thus, TmpA might be a useful antigen for monitoring successful treatment of syphilis.

Serological identification of pig enterotoxigenic Escherichia coli strains not belonging to the classical serotypes.

Escherichia coli strains isolated from pigs suspected to have succumbed to E. coli enterotoxicosis and not belonging to the commonly incriminated (classical) serotypes (O8:K87:K88, O45:K88, O138:K81:K88, O141:K85:K88, O147:K89:K88, O149:K91;K88, and O157:K88) were tested for enterotoxigenicity in the ligated gut test (LGT) using pig intestine. Of 202 strains tested, 54 strains belonging to 13 different O groups were positive in the LGT. Four of these strains had K88 antigen and one possessed K99 antigen. The majority of the strains was not agglutinated by any of the standard OK antisera. Four new K antigens ("K200", "K442", "K2346" and "K2347") were provisionally designated. K200 was found in pig enterotoxigenic strains belonging to O group 8 and carrying flagellar antigen H31 and in non-enterotoxigenic non-motile strains of O group 8, as well as in O group 20 strains isolated from calves succumbing to E. coli septicemia in two countries. The provisional antigen K2346 was encountered in 18 enterotoxigenic strains with various O antigens from two countries. It is proposed to include these two K antigens into the international E. coli antigens scheme. Attempts to demonstrate a common antigen in the nonclassical enterotoxigenic strains lacking K88 and K99 antigens failed.

Detection of the K99 antigen by means of agglutination and immunoelectrophoresis in Escherichia coli isolates from calves and its correlation with entertoxigenicity.

The common antigen of calf enterotoxigenic strains of Escherichia coli, recently established as the K99 antigen, was studied by means of the slide agglutination test and immunoelectrophoresis. Specific antisera were obtained by absorption of crude antisera with ultrasonicates of autologous cells grown at 18C or by injection into rabbits of the purifies K99 antigen obtained by preparative electrophoresis. The K99 antigen was usually undetectable in calf enterotoxigenic E. coli cultures with capsular K antigens of the A variety grown at 37C on commercially available nutrient agar plates designed for the isolation of Enterobacteriaceae, but was rapidly detectable when grown on a buffered semi-synthetic medium at pH 7.5 (Minca medium). An alternative procedure for the isolation and identification of calf entertosigenic E. coli strains from feces, using the Minca medium, is proposed. K99 was found in 70 of 74 strains of E. coli, the enterotixigenicity of which was established in the ligated gut test in calves. None of the 20 cultures negative in the ligated gut test possessed K99 antigen. The K99 antigen is therefore probably a useful diagnostic tool for the identification of calf enterotixigenic E. coli strains, taking into account that K99 and enterotoxigenicity are controlled by different plasmids.

Escherichia coli O antigen typing by means of a mechanized microtechnique.

A mechanized microtechnique for the serological typing of Escherichia coli cultures is described.