- Volume 13, Issue 3, 1980

The intramammary pathogenicity of four strains of Streptococcus dysgalactiae was measured by infusion of small numbers of bacteria (8–16 colony-forming units) into the teat sinus after milking. Significant differences in the infectivity of strains were detected.

Plesiomonas Shigelloides has been implicated as an aetiological agent in sporadic cases and outbreaks of diarrhoea, and in food poisoning, in various parts of the world. (Schmid, Velaudapillai and Niles, 1954; Osada and Shibata, 1956; Vandepitte et al., 1957; Ueda, Yamasaki and Hori, 1963; Aldova, Rakovsky and Chovanova, 1966; Geizer, Kopecky and Aldova, 1966; Hori et al., 1966; Cooper and Brown, 1968; Pauŝova and Fukalova, 1968; von Graevenitz and Mensch, 1968; Winton, 1968; Sakazaki et al., 1971; Chatterjee and Neogy, 1972; Sanyal et al., 1972a and b; Zajc-Satler, Dragas and Kumelj, 1972; Bhat, Shantha Kumari and Rajan, 1974; Vandepitte, Makulu and Gatti, 1974; Sanyal, Singh and Sen, 1975; Jandl and Linke, 1976; Tsukamoto et al., 1978). P. shigelloides was isolated in pure culture from stools of patients with diarrhoea of otherwise unexplained origin, and more often from patients than from symptomless persons. Experimental evidence has not, however, been reported in support of its enteropathogenicity, except our preliminary communication on the activity of a few strains in the rabbit ileal-loop model (Saraswathi, Sharma and Sanyal, 1978). The present investigation was undertaken to examine its enterotoxicity and invasiveness.

Only one of 23 gentamicin-resistant cultures of Staphylococcus aureus transferred its resistance in mixed culture in broth to the non-lysogenic S. aureus strain 1030; the transfer-frequency was 10−3–10−4. Transfer between non-lysogenic clones of strain 1030 occurred at a similar frequency in urine, and at a frequency of ~10−1 in serum.

The resistance determinant for transfer between non-lysogenic clones was usually linked to phage genome, as shown by the possession by resistant recipients of immunity to typing phage 75, plaque-forming particles in their culture filtrates and inducibility by mitomycin C. Stability of the resistance on storage and transduction kinetics suggested that these genes were chromosomal.

Two resistant derivatives were isolated that had lost some phage functions and were unable to transfer their resistance further. The epidemiology of gentamicin resistance may in part be explicable by the transient formation of an auto-transmissible element with subsequent integration of the resistance genes into a variety of replicons (i.e., transposition).

There are difficulties in the diagnosis of deep-seated candidosis; the clinical features are non-specific and similar to bacterial infections, and blood cultures may be negative even when there is an active invasion of the deep tissues.

Serology, especially precipitin tests, are considered a useful diagnostic adjunct (Taschdjian, Seelig and Kozinn, 1973; Odds, 1979) but precipitins to extracts of Candida albicans have been detected in sera from apparently normal subjects (Douchet and Müller, 1972; Everall, Morris and Morris, 1974), pregnant women (Stanley, Hurley and Carroll, 1972), burned patients (Oblack, Schwartz and Holder, 1976), patients given intravenous hyperalimentation (Glew et al., 1975) and in patients after open heart surgery (Murray, Buckley and Turner, 1969; Parsons and Nassau, 1974; Evans and Forster, 1976). These 'false positive' antibodies may often be directed to the cell-wall mannans of C. albicans (Pepys et al., 1968).

Although attempts have been made to introduce new tests for candida antibodies (Stickle et al., 1972; Müller, 1974) it is unlikely that any serological test can be more specific than the antigenic reagents on which it is based. Most efforts to overcome the problem of poor specificity have involved either the modification of candida extracts by removal of the mannan antigens (Long-bottom et al., 1976; Syverson and Buckley, 1977; Syverson, Buckley and Gibian, 1978) or a search for novel antigenic components unique to the hyphal form of the fungus (Evans et al., 1973; Syverson, Buckley and Campbell, 1975). Staib and his co-workers (1977a and b) have suggested that an inducible acid proteinase secreted by C. albicans may be a useful diagnostic antigen; but they appear to have tested only unrefined culture filtrates containing the enzyme, with equivocal results.

This paper describes a simple method for the rapid purification of C. albicans proteinase which is a development of the procedure of Remold, Fasold and Staib (1968). The value of the purified enzyme as an antigen for use in the diagnosis of systemic candidosis is assessed in tests with sera from experimental animals and humans.

A series of 156 cultures of Escherichia coli isolated from sequential urines from 20 patients with urinary-tract infection was examined by biotyping, resistotyping, haemagglutinin typing, 0 serotyping and antibiogram typing, From 10 of the patients, we repeatedly isolated cultures of a single strain; from each of the other 10 patients, different strains were discriminated.

All cultures were typable by biotyping and resistotyping, and those techniques should prove practicable for laboratories not able to perform complete serological analysis. Only a minority (43.6%) of the cultures was typed with a limited range of 24 commercial O sera.

Maximum discrimination of strains was achieved by the combined use of several of these techniques.

An Epidemic form of enteritis necroticans, locally known as pig-bel, occurs in children in the highlands of Papua New Guinea (Murrell and Roth, 1963; Murrell et al., 1966a). The disease is a serious public-health problem with an annual mortality of about 14 per 10,000 population (Murrell et al., 1966b). It is now the commonest cause of death in Eastern Highland Hospitals among children over 1 year of age and it is estimated that approximately 750 children die from pig-bel each year. Evidence suggests that the condition is precipitated by the growth of strains of Clostridium perfringens type C (Egerton and Walker, 1964) present in small numbers in the normal intestinal flora or ingested with contaminated meat during pig feasting, with subsequent production of β toxin leading to segmental paralysis, inflammation and necrosis of the small intestine. The normal low-protein diet, the staple sweet potato, a dietary change to meat particularly during pig feasting, and low levels of β antitoxin in those at risk are thought to be predisposing factors in the pathogenesis of this gangrenous enteritis (Lawrence and Walker, 1976). Only small amounts of pancreatic protease, particularly trypsin which is known to destroy β toxin, are produced by children on a low-protein diet; this, coupled with the presence of trypsin inhibitors in semi-cooked sweet potato, may be of particular importance (Lawrence, 1974, 1975).

Pig-bel may present in several ways. In the acute toxic form, with toxaemia and shock, abdominal symptoms may be prominent; in the acute surgical form there is obstruction of the small bowel and severe pain, and surgery is life-saving; and in the subacute surgical form there is a degree of small-bowel obstruction with subsequent malabsorption resulting from scarring and fibrosis. The most common form is mild and there is usually complete recovery.

How the toxin penetrates the jejunal mucosa is not clearly understood. According to Lawrence (1974), the clinical course of pig-bel reflects the amount of damage done by large amounts of toxin produced in a short period after the meat meal that invariably precedes the disease. This process is localised in time, the damage done to the gut by absorption of toxin early in the

The water-soluble components of Aspergillus fumigatus mycelium were partially separated by fractional precipitation with ammonium sulphate. The total protein and neutral-sugar content were determined for each of the four fractions prepared and their immunological activity was examined by double diffusion. Partial chemical characterisation of these isolates by polyacrylamide-gel electrophoresis was linked to their precipitability by allowing the separated components to diffuse from the gel into an agarose medium containing an appropriate antiserum. The distribution and reactivity of antigens was monitored by two-dimensional immunoelectrophoresis with rabbit sera raised against either mycelial or culture-filtrate antigens and human sera, obtained from patients with aspergilloma and from patients with allergic bronchopulmonary aspergillosis. This technique was also used to establish that considerable variation exists in the precipitation profile seen among patient specimens. Several antigens were found to possess sugar residues that interacted with concanavalin A, when this lectin was used in an intermediate gel in two-dimensional immunoelectrophoresis.

Several explanations have been proposed to account for the Dienes phenomenon that occurs between some strains of Proteus (Dienes, 1946). Senior (1977) suggested that proticines played a major role in the phenomenon but that not all the results could be explained in this way.

The term "colony incompatibility" was coined by Bettelheim and Carlile (1976) to include the Dienes phenomenon of Proteus as well as similar interactions among other motile bacteria. Recent studies of salmonellas (Bettelheim, 1978a and b) have shown that neither serotype nor bacteriocine production nor phage type correlate with incompatibility. Although colony incompatibility is still unexplained, it was decided to examine its possible ecological significance in a hospital environment.

Various views are held about the antibacterial mechanisms operating on the skin surface (for reviews see Burtenshaw, 1945; Naylor and Rook, 1968). Substances resembling long-chain fatty acids extracted from normal skin by Burtenshaw (1945) had a marked bactericidal action on Streptococcus pyogenes. Ricketts, Squire and Topley (1951) suggested that a chemical mechanism was largely responsible for the destruction of Str. pyogenes on the skin, whereas drying is responsible for the destruction of Escherichia coli and Pseudomonas aeruginosa; both factors appeared to contribute to the elimination of Staphylococcus aureus. They concluded that unsaturated fatty acids, particularly oleic acid, are the active chemical agents. These fatty acids may be produced on the skin surface as a result of the splitting of esters in the sebum by the commensal flora (Scheimann et al., 1960; Davidson, 1965; Naylor, 1970).

Many workers have studied the antibacterial action of lipids in vitro (Walker, 1924; Dubos, 1947; Pollock, 1948; Nieman, 1954; Galbraith et al., 1971; Butcher, King and Dyke, 1976), usually in fluid media in which suspensions of bacteria had been added to emulsions of various lipids. Burtenshaw (1945) was unable to demonstrate an antibacterial effect with lipid substances placed in punched-out holes in an agar medium containing haemolytic streptococci; he concluded that antibacterial lipids did not diffuse in agar medium. Dubos (1947) described the influence of various lipids incorporated in solid media on the number and diameter of bacterial colonies.

Because the lipids on the skin probably exist as a water-in-lipid emulsion (Herrmann, Prose and Sulzberger, 1953), experimental procedures with a solid medium probably imitate the physical conditions on the skin better than studies of suspensions of bacteria in aqueous solutions containing fine droplets of emulsified lipid (Milyani and Selwyn, 1978). The following qualitative and quantitative studies take account of this view. A preliminary report of the qualitative method was given by Naylor (1970).

Leptospira interrogans serovar balcanica was haemolytic for washed human, cattle, sheep and possum red blood cells (RBC); serovar hardjo was non-haemolytic. A test for haemolysis may prove useful in the preliminary differentiation of balcanica and hardjo isolates. Balcanica was non-haemolytic for unwashed RBC from human and bovine donors whose serum contained Hebdomadis serogroup antibody. Haemolytic activity tended to disappear with repeated subculture of balcanica.