- Volume 29, Issue 2, 1989

Administration of oestradiol to three strains of female mice induced the oestrous phase of the reproductive cycle in which there are few or no polymorphonuclear leucocytes (PMNL) in vaginal smears. This treatment rendered the mice susceptible to genital tract colonisation by serotype 8 of Ureaplasma urealyticum, inoculated intravaginally. BALB/c mice were the most susceptible, all of 10 becoming colonised; two other strains were less susceptible and untreated mice were resistant. The numbers of ureaplasmas recovered from the vagina ranged from 102 to 107 colour-changing units (ccu)/ml, irrespective of the strain of mice, and in some there was spread to the uterine horns and ovaries, and to the spleen in one mouse. Vaginal colonisation persisted for 21-163 days and subsequent failure to recover the organisms seemed to be associated with re-establishment of the oestrous cycle. There was no evidence of a genital tract PMNL response but some of the mice developed a fourfold or greater antibody response, measured by the metabolism-inhibition technique. This, however, was insufficient to protect mice against recolonisation by the same serotype of U. urealyticum.

A collection of 45 serologically distinct strains of Morganella morganii from several European countries was typed by morganocin production (p) and sensitivity (s). This permitted their differentiation into 33 morganocin p/s types; 15 new types of morganocin and one new morganocin sensitivity type were found and are defined. Morganocin production and sensitivity characteristics appeared to be unrelated to the O and H antigens of the strain. The finest strain recognition in M. morganii might be achieved by a combination of bacteriocin and serotyping methods.

The SOS DNA repair system is induced in bacteria treated with 4-quinolones. However, whether the response exacerbates or repairs the damage caused by these drugs is still unclear. The recA13 and the recB21 mutations impair recombination repair and render bacteria unable to induce the SOS response when treated with nalidixic acid or other agents that affect DNA synthesis. However, UV treatment induces the SOS response in recB21 mutants but not in recA13 mutants. Both these mutants are hypersensitive to nalidixic acid and, therefore, either recombination repair or SOS repair would appear to repair DNA damage caused by the drug. However, since the lexA3 mutation (which also renders bacteria incapable of inducing the SOS response without affecting recombination repair) had no effect on the susceptibility of bacteria to nalidixic acid, the SOS response neither contributes to nor repairs DNA damage caused by the drug. Consequently, it would seem that the hypersensitivity of the recA13 and recB21 mutants to nalidixic acid is due to their deficiency in recombination repair. This view was confirmed by testing a recA430 mutant that is recombination-repair proficient but SOS repair-deficient and finding it to be no more sensitive to nalidixic acid than its parent. Thus it would appear that, although induced by nalidixic acid treatment, the SOS DNA repair system does not play any role in bacterial responses to the damage caused by the drug. In contrast, the recombination repair system does repair damage caused by nalidixic acid.

An affinity procedure with purified, biotinylated human transferrin and streptavidin-agarose was used to identify the transferrin-binding proteins in strains of Haemophilus influenzae. Proteins of 58 and 98 Kda were isolated from total membranes prepared from iron-deficient but not iron-sufficient H. influenzae KC548 cells. The 58-Kda protein was capable of binding human transferrin after sodium dodecyl sulphate (SDS)-polyacrylamide gel electrophoresis (PAGE) and electroblotting. Isolation of transferrin-binding proteins from type-b and non-typable H. influenzae strains demonstrated some variability in the size of the higher mol. wt protein (94–106 Kda) and in ease of elution of the smaller protein from the affinity resin. Use of purified, biotinylated human lactoferrin in the affinity isolation procedure with membranes from a strain expressing lactoferrin-binding activity resulted in isolation of proteins of 105 and 106 Kda distinct from the transferrin-binding proteins.

Strains of Escherichia coli isolated from urinary tract infections and meningitis were characterised by their O:K serotype, haemolysin production, mannose-resistant haemagglutination, and the serotype of the P-fimbriae. The P-fimbriae of 71% of the mannose-resistant haemagglutination-positive strains from urinary tract infection and meningitis could be determined with specific monoclonal antibodies. Many strains expressed multiple P-fimbriae serotypes. The serotypes of P-fimbriae found most frequently among mannose-resistant haemagglutination-positive E. coli from urinary tract infections were the F11, F71 and F8 fimbriae, and among meningitic strains, F11, F8 and F9 fimbriae. The expression of certain F-serotypes did not correlate with O:K antigens.

Escherichia coli strain R1, originally isolated from a patient whose burns were treated with silver sulphadiazine, contained two large plasmids of 83 kb (pJT1) and 77 kb (pJT2), and was resistant to 1 mm AgNO3. A silver-sensitive derivative, E. coli S1, cured of the 83-kb plasmid pJT1, was obtained by growth at 46°C. Studies with an Ag+ -specific ion electrode showed no significant differences in Ag+ binding by washed resting cell suspensions of strains R1 and S1, with and without glucose. However, transmission electronmicroscopy and energy dispersive X-ray analysis of whole cell mounts from actively growing cultures showed that the Ag+-resistant strain did not accumulate Ag+, whereas the sensitive strain contained dense silver particles. Both strains produced H2S, detected by blackening of lead acetate paper above inoculated broth, and reducing substances (possibly H2S) were detected only around E. coli R1 colonies when methylene blue was used as a indicator in LB agar, which may be a less sensitive assay. The mechanism of silver resistance is not known, but actively growing cells of E. coli R1 did not accumulate silver.

Hamsters were immunised with leptospiral lipopolysaccharide (LPS) or the polysaccharide (PS) fraction of LPS from Leptospira interrogans serovar copenhageni and the antibody responses were measured by agglutination tests. Maximum titres were observed approximately 6 weeks after immunisation and protection against lethal challenge with the homologous strain was afforded by immunisation with as little as 2.5 μg of LPS or PS. All animals produced IgM agglutinins but a higher proportion of animals immunised with PS produced IgG agglutinins than did those immunised with LPS. Immunisation of guinea-pigs with autoclaved PS showed that the preparation retained some but not all of its immunogenic activity.

A novel replicating agent (IFDO) was isolated from ileal fluid. Growth occurred in vitro under aerobic and anaerobic conditions, and was faster at 37°C than at room temperature. The doubling time was 15.8 min. Colonies were dark brown in colour and occurred beneath the surface of agar after conventional surface inoculation. Provisional data indicate that the agent may be a normal intestinal commensal. The agent was remarkably resistant to inactivation by steam at 134°C, formaldehyde and glutaraldehyde; it was relatively resistant to ionising radiation, and it was filterable through membranes with a nominal pore diameter of 10 nm. Such properties, with the exception of growth in cell-free medium, are shared by “unconventional agents” such as those of Creutzfeldt-Jakob disease and scrapie. Further comparison of the properties of the intestinal agent and of slow viruses revealed additional shared characteristics, including resistance to proteinase K and trypsin, and inactivation by guanidine thiocyanate, diethyl pyrocarbonate, phenol and sodium hydroxide. The agent differs from that of scrapie in being inactivated by ethidium bromide, zinc nitrate, EDTA, hydroxylamine in the presence Sarkosyl, and, under certain circumstances, by ribonuclease. Broth cultures of the agent contained particles possessing considerable size heterogeneity. The smaller filterable particles were generally more susceptible to inactivation, did not survive autoclaving, and were inactivated by papaya protease and lipase. It is possible that the replicating agent may be formed by crystallisation from constituents of the medium, and not by a biological process. This does not exclude the postulated relationship to slow viruses.

Immunologically potent RNA-protein extracted from Mycobacterium tuberculosis strain H37Ra, when entrapped in phosphatidylcholine multilamellar liposomes and injected into mice, induced both cellular and humoral immune responses. Significant protection against infection with M. tuberculosis H37Rv was also induced in the immunised mice, as monitored by (i) higher survival rates, (ii) decreased viable counts of M. tuberculosis H37Rv in lungs, livers and spleens, (iii) lower lung density, and (iv) lower root specific lung weight, in comparison with a control group of unimmunised mice.