- Volume 14, Issue 4, 1981

Attempts were made to infect grivet monkeys with Ureaplasma urealyticum, including strains freshly isolated from patients with infection of the genito-urinary tract, laboratory reference strains and simian strains. The organisms were inoculated directly into the uterine tubes exposed at laparotomy, or through the cervical canal into the uterine cavity before endometrial curettage; but only colonisation, of up to 5 months’ duration, was achieved, without evidence of inflammation in the genital tract or elsewhere, and without an antibody response.

Serotypes and phage types of group-B streptococci isolated from healthy and diseased human subjects and from cattle in different parts of Norway have been compared. The phage set used was found to be suitable for the study of strains from cows as well as from man.

Antibodies against commercially available antigens of Candida albicans were assayed in 54 sera from 24 patients with fungaemia and in 66 sera from 33 patients with bacteraemia. In patients with persistent fungaemia, antibody was found during the week after the fungus was first cultured from the blood, but peak titres did not usually occur until the end of the second week. A significant rise of titre in C. albicans infection was observed in 50% of paired sera tested by passive haemagglutination (PHA), indirect immunofluorescence (IF) and Ouchterlony immunodiffusion (ID). The same percentage was obtained by counterimmunoelectrophoresis (CIE) against candida metabolic antigens, whereas it was increased to 88% when somatic antigens were used. Enzyme-linked immunosorbent assay (ELISA) demonstrated a rise of titre in 25, 75 and 50% of sera in IgM, IgG and IgA assays, respectively. Sera from patients with transient fungaemia demonstrated persistent antibody titres.

In paired sera from patients with bacteraemia, ID and CIE titres were low (⩽4). There was an increase of candida antibodies in 0–9% of patients by ELISA, ID or CIE and in 18–21% by PHA or IF. Clinically significant fungaemia was most reliably differentiated serologically from bacteraemia by CIE S-antigen and ELISA IgG assays.

Evidence is presented that the high susceptibility of armadillos to infection with Mycobacterium leprae cannot be explained solely in terms of body temperature because mutant mice maintained with a body temperature similar to that of armadillos do not become heavily infected with M. leprae. The depression of cell-mediated immunity accompanying the low body temperature is not sufficient to produce an overwhelming infection. The results obtained with M. marinum suggest that whereas lack of cell-mediated immunity or a low body temperature result in a moderately enhanced infection in the mouse a combination of both of these factors is required to produce an overwhelming infection involving the internal organs.

Of 3952 clinical isolates of Enterobacteriaceae, 246 exhibited resistance to at least carbenicillin, gentamicin and tobramycin. All these isolates, representing eight genera, were resistant to at least nine antimicrobial agents in common, including the three key antibiotics and streptomycin, kanamycin, sisomycin, ampicillin, cephalothin and sul-phonamide. The strains could be subdivided into seven groups depending upon additional resistance traits and some were resistant to as many as 15 antibiotics. When mated with a standard strain of Escherichia coli, 85% of 123 randomly selected donors transferred resistance to at least the nine core antibiotics. Some donors occasionally transferred resistance to two additional antibiotics, neomycin and tetracycline, while one Citrobacter freundi donor always transferred linked resistance to all 11 drugs. Although many donors were found to harbour more than one species of plasmid DNA, all except a strain of C. freundi contained at least a plasmid of mol. wt 89 × 106. Analysis of E. coli transconjugants showed this plasmid to be responsible for transferable resistance to the nine core antibiotics. Restriction-endonuclease analysis indicates that the 89 × 106 plasmids originating from different isolates were essentially identical with each other. These results show that a particular R plasmid has established itself among the Enterobacteriaceae at Hines VA Hospital. This R plasmid appears to be the predominant genetic element responsible for linked resistance to carbenicillin, gentamicin and tobramycin among these hospital-associated bacteria.

The opsonic and protective capacities of rabbit antisera against Escherichia coli O, K and core-glycolipid cell-wall antigens were compared with specific antibody titres as measured by agglutination and enzyme-linked immunosorbent assay. Anti-O antisera were opsonic and protective against two noncapsulate strains. Only anti-K antisera were opsonic and protective against a K-antigen-containing strain. In a mouse model anti-core-glycolipid antiserum was not protective against challenge even by a strain bearing only core glycolipid.

Phagocytosis and intracellular killing of several facultative anaerobes were observed in aerobic and anaerobic conditions. The presence of anaerobes affected these processes. Bacteroides asaccharolyticus and B. fragilis were killed by phagocytes only at bacterial concentrations less than 1 × 107 cfu/ml; at higher concentrations of the anaerobes, killing of B. fragilis and concomitant facultative anaerobes was inhibited. This effect appeared to be due to an interaction, in appropriate reducing conditions, between anaerobe and serum, which allowed engulfment of organisms by phagocytes but markedly impaired intracellular killing.

The suckling-mouse assay was reliable for detecting enterotoxigenic strains of Aeromonas hydrophila when standard conditions for growth and toxin testing were used. Enterotoxins were produced by bacteria grown in tryptone soya broth supplemented with yeast extract and aerated by shaking in an environmental incubator or water bath. When culture supernates together with dye were administered intragastrically to mice less than 6 days old, the presence of enterotoxin was assessed on the basis of a scoring system that incorporated the ratio intestinal weight: remaining body weight, and production of diarrhoea. This method should facilitate the detection of enterotoxigenic strains of Aeromonas in epidemiological studies.

Modulation of Bordetella pertussis was induced by growth in Hornibrook medium with a high content of magnesium sulphate (C-medium); four pathophysiological activities in the cells or in the whole culture were measured at intervals. Modulation, shown by the extensive loss of protective antigen, histamine-sensitising factor, leuko-cytosis-promoting factor, heat-labile toxin and X-mode specific envelope proteins, occurred during the first 10 h of incubation of X-mode cells in C-medium at 35°C and before the onset of the logarithmic phase of growth. The rapidity of these losses was greater than could be explained by a simple growth-dilution effect and did not appear to be due to release of activity into the culture fluid. It seemed, therefore, that there was selective destruction of pathophysiological activities as well as cessation of synthesis. The activities appeared to be lost at different rates. Mouse-protective activity was lost more rapidly than histamine-sensitising and leukocytosis-promotmg activities; heat-labile toxicity was lost more slowly or less completely. Modulation was shown to be easily reversed.

Strains of mice immunised with a ribosomal preparation of Salmonella typhimurium varied in their ability to survive an intraperitoneal challenge of virulent S. typhimurium. Immunised nude (nu/nu), heterozygous (nu/ + ) mice, strain C57B1/6J and strain CBA/J succumbed to lethal infection whereas strains C3D2F1/J, B6D2F1/J and A/J, and Swiss mice were fully protected. Strains DBA/2J and C3H/HeJ were partially protected.

Enumeration of the systemic bacterial population after challenge with S. typhimurium indicated that all immunised mouse strains were able to reduce the infectious load. S. typhimurium was rapidly inactivated in the peritoneal cavity of immunised mice, effectively reducing the challenge and thereby limiting the number of organisms available to seed the systemic circulation. This response was also obtained in immunised athymic mice and was therefore attributed to a T-cell independent antibody response. Organisms that escaped destruction in the peritoneal cavity multiplied rapidly in the reticuloendothelial organs. Only mice from strains genetically capable of developing an effective cell-mediated immune response to the antigenic stimulus provided by the challenge organism itself survived infection.

The efficacy of ribosomal immunisation was compared with immunisation by heat-killed bacteria, viable attenuated and viable virulent organisms by enumeration of the systemic bacterial population after intravenous challenge with S. typhimurium. Vaccination with ribosomal preparations or heat-killed organisms provided limited protection whereas immunity provided by viable organisms was far superior.

Four non-immune sheep and two with naturally acquired antibody were inoculated subcutaneously in the lower part of the leg with 100 cysts of Toxoplasma gondii. Two other non-immune sheep were given a control inoculum. Efferent lymph from the popliteal nodes on the side of the injection was collected via a cannula and injected into mice. Live toxoplasms were present in the lymph of non-immune sheep from day 2 until day 15, at which time the experiment was terminated. Corresponding samples of lymph from the one immune animal tested were almost always negative.

Severe pathological changes were present in lymph nodes from non-immune sheep. Gross enlargement, loss of architecture, haemorrhages, and some necrosis occurred, and the sinuses were packed with plasma cells and plasmablasts. Changes in the nodes of immune sheep were similar but less striking, with retention of architecture, no haemorrhages and no necrosis. It was concluded that the lymphadeno-pathy in sheep is similar to that in rabbits, mice and man with toxoplasmosis.

The ability of Klebsiella aerogenes strains isolated from outbreaks of infection, from sporadic infections and from the environment to survive on hands were compared. Considered as groups, the outbreak strains survived best and the environmental strains least well. The possible importance of these observations in relation to outbreaks of klebsiella infection in hospitals and to heterogeneity of pathogenic potential and transmissibility in Klebsiella aerogenes is discussed.

The cytotoxicity of klebsiella capsular antisera for lymphocytes from 10 HLA B27-positive patients with ankylosing spondylitis and eight B27-negative normal control subjects was examined. None of the antisera was cytotoxic for lymphocytes from nine patients but several antisera were cytotoxic for the lymphocytes from one patient. There were no differences between the results obtained with lymphocytes from the nine patients and those with lymphocytes from the normal controls. If klebsiella carriage is important in the pathogenesis of ankylosing spondylitis, the results of this investigation suggest that the capsular antigen is probably not involved.

The quantitative and qualitative changes occurring in the fungal flora of 22 patients with oral and 9 with laryngeal carcinoma were studied during and after radiation therapy. Each patient received 6000 rad of externally applied radiation in divided doses for 5 weeks. The fungal flora was isolated from the patients’ oral cavity and irradiated skin sites during irradiation and 2 weeks and 4–6 months afterwards. The number and types of fungi increased in both groups of patients after the start of irradiation and persisted at high levels for at least 4–6 months after treatment. Candida albicans and C. tropicalis were the principal yeasts isolated throughout the period studied but seven other species were also identified. All the yeast isolates were sensitive in vitro to miconazole, ketoconazole, amphotericin B and nystatin. Any of these antifungal agents should be appropriate for therapy.