- Volume 9, Issue 1, 1976

Compounds extracted from the aqueous phase of an autoxidising linolenic acid-buffer dispersion possess selective antibacterial properties. Experimental evidence suggests that these activities are in part a function of the aldehydic intermediates.

Evidence is presented for the chromosomal location of the coagulase determinant in most strains of Staphylococcus awreus. By the use of a pour-plate technique, transduction of the capacity to produce coagulase to a coagulase-negative mutant of S. aureus was studied. The frequencies of transduction were low unless the transducing phage was exposed to ultraviolet irradiation and the recipient was lysogenised with the transducing phage. Attempts to transfer the coagulase gene from S. aureus to S. epidermidis were not successful.

Small-bowel content was examined bacteriologically whilst fresh and after storage for 24, 48, and 72 h in a modified Stuart's medium. There was little alteration in the viable count of individual intestinal organisms. For accurate quantitative analysis, 0.3 ml of intestinal content was enough.

Specimens of small-bowel content were obtained by needle aspiration, and a qualitative and quantitative study was made of the microflora of patients with acute intestinal obstruction and of a control group of patients. Results in the control group confirmed the findings of the results of intubation studies by other workers, that a quantitative gradient of aerobic and anaerobic organisms exists from jejunum to distal ileum. In acute small-bowel obstruction and acute large-bowel obstruction there was a loss of the normal gradient and an increase in the absolute numbers of organisms present; this was particularly marked for anaerobic organisms in large-bowel obstruction.

Prototheca wickerhamii was treated in vitro with 11 different herbicides and plant hormones. Growth was inhibited by indolyl-3-acetic acid, indolyl-3-butyric acid and indolyl-3-propionic acid at 400 μg per ml. Coconut milk was stimulatory.

Leptospira interrogam serotype canicola (strain NADL A-13) grew from inocula as small as two cells in liquid polysorbate 80 medium (P-80 medium), in P-60, P-40 and P-20 media, and in P-80 medium from which polysorbate, NH4Cl or thiamine had been omitted. It grew well initially in vitamin B12-deleted P-80 medium, but only with inocula as large as 26 × 104 cells per ml.

P-80 medium lacking both polysorbate and NH4Cl supported light growth from small inocula, but the omission of thiamine and vitamin B12 in addition seriously affected the properties of the medium. Where readily detectable growth did not develop in liquid nutrient-deleted medium, viable organisms could often be demonstrated indirectly by subculture to semisolid medium, and their occurrence was influenced by the presence of albumin, thiamine, and vitamin B12.

Growth on semisolid media was comparable with that in liquid media of similar composition. The absence of poly sorbate 80, thiamine, or vitamin B ! 2 prevented the appearance of Dinger's zones of growth from small inocula.

Antigenic composition as measured by microscopic agglutination tests with homologous and heterologous antisera was not appreciably affected by repeated subculturing in various complete and incomplete media.

Homogenates of infected-hamster-kidney tissue in bovine serum-albumin diluent still contained viable organisms after 60 days' storage at 23-25°C. Organisms derived from this material after 3 and 16 days' storage showed no loss of virulence. Organisms grown in artificial culture showed no loss of virulence after storage in bovine albumin diluent or phosphate buffer for 7 days at 23-25°C.

Cultures of the organism survived without loss of virulence for 15 months in 13 semisolid media of differing complexity. Single colonies derived from five different solid media were grown in semisolid forms of the parent media and stored at 23-25°C for 10 months without loss of virulence.

Nine strains of glycolytic mycoplasmas isolated from the respiratory tract of apparently healthy sheep, pneumonic sheep and sheep with pulmonary adenomatosis (SPA) were compared with a Queensland strain (Y98) of Mycoplasma ovipneumoniae. All strains were very similar in their reactions in 14 biochemical tests and in their sensitivities to optochin, digitonin, sodium polyanethol sulphonate, and 11 antibiotics. Polyacrylamide-gel electrophoresis and serological cross-reactions by the agar-gel double diffusion, metabolic-inhibition (MI) and growth-inhibition (GI) tests also showed that all strains could be classified as M. ovipneumoniae.

The MI and GI tests, however, showed considerable intraspecific differences among strains, with apparent polarisation of SPA strains and non-SPA strains at opposite ends of the antigenic spectrum.

Two representative strains were tested by the MI test against antisera to 39 mycoplasma species or serogroups, with negative results.

Dispersal of skin micro-organisms into the air during undressing was studied in 72 members of surgical and nursing staff. Few pathogens were found to be dispersed. Males dispersed more normal skin organisms than did females. Males were also more heavily colonised than females, and sex differences in dispersal diminished when allowance was made for the denser colonisation of males. Dispersal was correlated most strongly with the counts on the thighs and abdomen in males but on the shins in females.

Clostridia were isolated from human faecal samples from England, Scotland, Wales, USA, Hong Kong, Uganda and Japan. Strains were identified on the basis of various biochemical reactions and on the type of fatty acid produced from glucose. Analysis of these acids was by gas-liquid chromatography.

Clostridium paraputrificum was common in stool samples from England, Scotland, Wales and USA, but rare in samples from Hong Kong, Uganda and Japan.

Different serotypes of group-A streptococci share common antigens that are closely associated with the type-specific determinant of M protein. By the use of selected human sera containing antibody to these M-associated antigens, we have shown that group-A streptococci can be divided into three categories. The majority of the opacity-factor-negative respiratory serotypes possess a shared M-associated antigen or antigens, to which high titres of antibody are common in patients with rheumatic fever, or patients recovering from upper respiratory infections with certain opacity-factor-negative serotypes. The antibody in these sera has a demonstrable but limited affinity for the M-associated antigens of strains belonging to a second category of M types, the majority of which are opacity-factor-positive serotypes of “throat” or “skin” origin. A third group, consisting mainly of opacity-factor-negative pyoderma serotypes, gave variable results and seemed to be intermediate between the other two categories. Complement-fixation-inhibition tests and absorption studies showed a marked degree of cross-reactivity between the M-associated antigens of the three categories.

Five Bordetella pertussis strains of phase I were grown in conventional casamino-acid medium and in media modified by adding high concentrations of MgSC>4 or nicotinic acid. Cells grown in high-magnesium media (in the C-mode) had only about 4% of the protective antigen (PA) and 6% of the histamine-sensitising factor (HSF) of cells from the normal medium. Envelopes from C-mode organisms when examined by SDS-PAGE showed a loss of 28k and 30k polypetide bands. Similar parallel losses of PA, HSF and 28k and 30k bands were found with cells from the high-nicotinic-acid medium. A medium with a high concentration of nicotinamide gave cells with normal amounts of PA, HSF and 28k and 30k bands. Growth in high concentrations of Na2SO4 caused partial losses of PA, HSF and 28k and 30k bands, while a high-succinate medium gave cells with somewhat diminished PA and HSF but without appreciable attenuation of the 28k and 30k bands.

Because of the close correlation between the presence or absence of PA, HSF and 28k and 30k envelope polypeptides, it is suggested that the latter may represent or be closely associated with the components responsible for PA and HSF activities.