Evaluation of rapid methods of identifying group B streptococci.

Rapid methods of identifying Lancefield group B streptococci were compared to the standard Fuller's extraction method. Such tests as sodium hippurate hydrolysis, bile tolerance, aesculin hydrolysis, pyruvate fermentation, Camp factor, pigmentation, and bacitracin haemolysis were tested on both routine clinical specimens and National Collection of Type Culture strains. The results show that pigmentation on Islams's medium was the most definitive test available rapidly to identify group B streptococci.

Use of pyruvate fermentation compared with tetrazolium reduction in the differentiation of group D streptococci.

The reduction of 2, 3, 5 triphenyltetrazolium chloride in the original medium of Barnes (Journal of General Microbiology, 14, 57, 1956), and in a modified medium, was compared with the ability to ferment pyruvate as a means of separating Streptococcus faecalis from all other group D streptococci. The tetrazolium reduction test gave an occasional negative reaction with Str. faecalis strains. In addition, a number of strains gave a weakly positive reaction in the test, as did some strains of Str. faecium and Str. bovis. With some batches of tetrazolium, these weak reactions with Str. faecalis were so frequent that interpretation of the results was difficult. On the other hand, all Str. faecalis strains, and no other group D streptococci, gave a positive pyruvate-fermentation reaction in 48 hours.

Failure of the fluorescent antibody reaction to identify penicillinase-producing gonococci.

The fluorescent antibody test is now widely used to confirm the identity of Neisseria gonorrhoeae but may fail to identify penicillinase-producing strains (PPNG). This problem arises when conjugates are used that incorporate only gonococci that are not penicillinase-producers. We have shown that conjugates prepared from mixtures of PPNG and non-penicillinase producing gonococci give good fluorescent reactions. This difference in the reactions of PPNG strains is clearly related to their penicillinase-producing abilities, further study of the antigenic relation between penicillinase production and the antigenic structure of N gonorrhoeae is evidently required.

A serum-free medium for testing fermentation reactions in Neisseria gonorrhoeae.

Gonococcal infections can no longer be considered exclusively urogenital but it is difficult in a busy routine laboratory to identify gonococci from non-genital sites, especially if other commensal neisseria are present. Unfortunately, conventional serum agar sugars sometimes give equivocal results. A fermentation medium is described for the identification of gonoccoci. On preliminary testing this medium gives rapid and reliable results and should prove to be much more helpful to the routine laboratory than conventional serum agar sugars. Its potential usefulness, as demonstrated by the results of our first 200 examinations, would seem to justify further study in the routine work of other laboratories.

Impaired bacteriological responses in babies after maternal iron dextran infusion.

The effect of a total dose infusion of iron dextran in pregnancy on 15 mothers and their babies was compared with 19 controls. The bacteriostatic effect and opsonising ability of the sera, of babies born to the treated mothers, were considerably impaired. This was associated with a significantly lower transferrin concentration in these mothers. Although these in vitro tests were not associated with an increase in overt infection during the perinatal period, they suggest the need for caution in the use of total dose infusions in pregnancy.

A shortened scheme for the identification of indifferent streptococci.

A shortened biochemical scheme was devised for the reliable identification of the 'viridans' streptococci. It compared favourably with the classical identification system of Colman and could be recommended for use in the busy routine laboratory to investigate streptococcal isolates from clinical sources.

Use of the API-ZYM system in rapid identification of alpha and non-haemolytic streptococci.

The API-ZYM method of detecting enzymes was tested using 99 streptococci isolated from clinical material and 14 type species obtained from the National Collection of Type Cultures. We found the method easy and reliable. The results obtained indicate that this method could be a useful identification system in busy routine clinical laboratories.

Grouping of streptococci by Streptex.

Streptex was compared to routine laboratory identification methods available. The results from Streptex sometimes required several attempts before final identification could be achieved. In the main, group D streptococci other than Strep. faecalis failed to group with the Streptex antisera, and this method cannot therefore be used exclusively as a means of identifying this group of streptococci.

The detection of leptospires by a chemiluminescent immunoassay.

Rabbit serum hyperimmune to Leptospira interrogans var icterohaemorrhagiae serovar icterohaemorrhagiae, reference strain RGA was conjugated to the chemiluminescent label ABEI (6-[N-(4-aminobutyl)-N-ethyl amino]-2,3-dihydrophthalazine-1,4-dione) in the presence of the coupling agent, EDC (1-ethyl-3(3-dimethyl amino-propyl)-carbodiimide HCl). The luminescent conjugate was incubated with homologous and heterologous antigens. The results indicate that chemiluminescence may provide an accurate and rapid method of detecting leptospires in biological fluids.

Rat-bite acquired leptospirosis.

We report a case of leptospirosis in a boy following a rat-bite, an unusual mode of transmission for this infection. The use of antibiotics for fever following a rat-bite is discussed.

Comparison of the DIFCO and Patoc 1 slide antigens in the screening of leptospirosis.

A comparison of the Patoc 1 slide agglutination (SAT) and DIFCO slide agglutination test for the screening of leptospirosis in man, cattle and coypu (Myocastor coypus Molina) is reported. The economic costs, convenience and availability of the antigens for the tests are analysed. It is recommended that slide agglutination methods alone are not sufficient for the routine diagnosis of leptospirosis.

Serological study of leptospiral infections and endogenous uveitis among horses and ponies in the United Kingdom.

The prevalence of antibody titres to a range of 20 leptospira antigens in the serum of horses and ponies with no ophthalmic abnormalities and with ophthalmoscopic evidence of endogenous uveal inflammatory disease was determined using a microscopic agglutination technique. Titres against leptospira antigens were observed in 13 out of 138 (9.1 per cent) animals with no ophthalmic abnormalities, and in three out of 27 (11.1 per cent) animals with anterior uveitis. Serovar sejroe was common to all seropositive animals with anterior uveitis. The results show that leptospira infection is not a major factor in the aetiology of equine anterior uveitis in the UK, but suggests that the organism may be associated with some cases of recurrent anterior uveitis.

Effect of tissue culture cells in promoting prolonged survival of N. Gonorrhoeae in artificial subcutaneous cavities of mice.

Both tissue culture cells and human epithelial cells ingest gonococci, and subsequently protect them from the lethal action of various bactericidal agents. Using the convenient chamber produced by the subcutaneous insertion of a polyvinyl ring, the fate of the gonococci in mice was studied in vivo. Both humoral and cellular factors have free access to the organisms, and under normal circumstances these do not survive longer than 3 days. However, when gonococci were protected within tissue culture cells, their survival was prolonged. Only eventual graft rejection caused the death of the tissue culture cells and gonococci contained within them.

Differential susceptibility of type 1 and type 4 gonococci to chlorhexidine (Hibitane).

Virulent Type 1 gonococci have been shown to be much more suceptible to the killing action of Hibitane gluconate than the avirulent Type 4. Those exploring the possibility of genital prophylaxis as a means of controlling gonorrhoea might find Hibitane worthy of consideration.

Detection and identification of gonococcal L-Forms using a direct immunofluorescence test.

A fluorescent antibody test was used to identify L-Forms of N. gonorrhoeae induced in vitro. It was possible to differentiate the Large Bodies of the L-Forms from parent gonococci and the fluorescent reaction remained specific in the presence of tissue culture cells. A possible method to identify L-Forms of gonococci from patients presenting with postgonococcal urethritis is described.

A comparison of live and formalised leptospiral microscopic agglutination test.

The sensitivity and reliability of a formalised leptospiral antigen battery was compared with a smaller battery of live leptospiral antigens with 152 human sera positive for leptospirosis. There was good concurrence of results between the formalised and live antigens, however the live battery did fail to detect some positive sera where the antibody level was low. The formalised antigens were more sensitive than the live (P less than 0.001) and more reliable in the detection of early leptospiral infection, but the live antigens were more specific in the determination of probable infecting serogroup.