ISOLATION AND IDENTIFICATION OF ENTEROCOCCI FROM THE INTESTINAL TRACT OF THE RAT

NORMAL INTESTINAL FLORA OF CATTLE FED HIGH-ROUGHAGE RATIONS

Maki, Leroy R. (University of Wyoming, Laramie), and Kay Picard. Normal intestinal flora of cattle fed high-roughage rations. J. Bacteriol. 89:1244-1249. 1965.-Intestinal bacteria were isolated from 15 cattle. Approximately 600 isolates were studied, and their presence and numbers in the duodenum, ileum, cecum, and colon were noted. Bacteria most frequently isolated from all parts of the intestinal tract included Escherichia coli, Streptococcus bovis, and species of Bacillus. Several groups of gram-positive rods could not be classified according to Bergey's Manual. Direct counts of intestinal contents indicated that 1 to 10% of the bacteria present were recovered.

The ecology of the streptococci

All species of streptococci are divided into several groups according to the ecological niches they occupy. Members of the lactic acid group are found only in the plant environment and the dairy. Members of the pyogenic group and the buccal and intestinal residents of the subthermophilic group are found in intimate association only with homeothermic hosts. Members of the virulent pyogenic group, such asStreptococcus pyogenes, S. equi, andS. infrequens, are restricted to single hosts-the human, the horse, and the pig-whereas others, such asS. agalactiae can be found in several hosts. The intestinal dwellers of the subthermophilic group,S. bovis andS. equinus, occur in several animal species and are not isolated from other sources. The superficially homogeneousS. faecalis of the "enteric" group may actually consist of a group specifically restricted to the human host, and of a second group distributed among wild animals, insects, and plants. The latter group differs from the human type by the ability to hydrolyze starch and to produce a rennin-proteolytic type of curd in milk.Streptococcus faecium is widely distributed in both the homeothermic and poikilothermic environments, but no properties which differentiate the sources are known.Streptococcus faecium biot.casseliflavus has been isolated only from insects and plants.Streptococcus uberis occurs on the bovine lips and skin. Unidentified streptococci from all environments vary widely in properties. Many resembleS. lactis, S. faecalis, andS. faecium.

Streptococcus faecium var. casselifavus, nov. var

Streptococcus faecium var. casseliflavus is a gram-positive, spherical cell. The cells occur chiefly as pairs within chains and elongate to ogive-shaped cells during growth. Growth is good on 5% bile salts-agar and in broth at 10 C, and in broth adjusted to pH 9.6 or containing 6.5% NaCl, but many strains fail to grow at 45 C. Litmus is reduced rapidly prior to formation of an acid curd. Few strains release ammonia from arginine or serine. The organism is not proteolytic and does not produce H(2)S or acetylmethylcarbinol, reduce nitrate, decarboxylate tyrosine, or produce slime on sucrose-agar. Most strains survive heating to 60 C for 30 min. It produces gray colonies on potassium tellurite agar, reduces 2,3,5-triphenyltetrazolium-HCl to a pink color, and ferments cellobiose, dextrin, maltose, mannose, and sorbitol, thus resembling S. faecalis. Like S. faecium, it produces peroxidase but not catalase on heated blood media, dissimilates malate, and ferments arabinose, melibiose, and salicin, but not melezitose. Like both species, it ferments dextrose, galactose, lactose, mannitol, sucrose, trehalose, and citrate. Properties peculiar to the variant include the high pH limiting initiation and termination of growth; the fermentation of alpha-methyl-d-glucoside, raffinose, and xylose; motility; and growth without blue button formation in ethyl violet broth. The water-soluble, pale lemon-yellow pigment is released into the aqueous phase only after the cell envelope is altered by fat solvents. The bacterium thrives as an epiphyte on plants.

Growth, morphogenesis, and virulence of Candida albicans after oral inoculation in the germ-free and conventional chick

Balish, Edward (Syracuse University, Syracuse, N.Y.), and A. W. Phillips. Growth, morphogenesis, and virulence of Candida albicans after oral inoculation in the germ-free and conventional chick. J. Bacteriol. 91:1736-1743. 1966.-The effects of intestinal bacteria on the multiplication, morphogenesis, and infectivity of Candida albicans in the alimentary tract were investigated by comparing results obtained in germ-free and conventional chicks after oral inoculation. This challenge resulted in the establishment of large numbers of the pathogen in the alimentary tract of each group of chicks; these numbers were increased in crop contents from challenged bacteria-free chicks wherein hyphae predominated over the yeast form. These animals also had lesions of the crop epithelium containing numerous hyphae and few yeast-like forms. In contrast, challenged conventional chicks receiving an adequate diet displayed no evidence of infection. Their alimentary tract contained the yeast form of C. albicans; no hyphae were seen. Although we found bacterial inhibition of C. albicans multiplication in the alimentary tract, this in itself did not seem to explain the resistance to intestinal candidiasis in our conventional chicks. We argued that this resistance to infection was due chiefly to the prevention of hyphal development in C. albicans by intestinal bacteria. C. albicans in the gut of our conventional chicks resulted in some increase in numbers of enterococci in contents from the crop. Increased pH values in contents from the gut of germ-free chicks were not clearly related to infection after challenge. The E(h) of the above crop contents were only slightly decreased in the germ-free crop. Thus the E(h) did not appear to be involved in susceptibility to infection. Invasion of the blood stream and kidneys of conventional chicks by the yeast form of C. albicans occurred in challenged animals receiving a purified diet which had been radiation-sterilized and stored for 6 months at room temperature (25 C). Their growth rate decreased and they became moribund; no hyphae were observed in tissues or intestine of these animals. Challenged bacteria-free chicks receiving the same diet were resistant to the above invasion, although they had crop lesions containing hyphae as described. The resistance of these chicks to systemic invasion was attributed to absence of intestinal bacteria competing for low levels of vitamins in the stored diet. Germ-free chicks had decreased levels of serum gamma-globulin which increased after challenge, whereas this value was unchanged in conventional birds after challenge.

Growth and virulence of Candida albicans after oral inoculation in the chick with a monoflora of either Escherichia coli or Streptococcus faecalis

Balish, Edward (Syracuse University, Syracuse, N.Y.), and A. W. Phillips. Growth and virulence of Candida albicans after oral inoculation in the chick with a monoflora of either Escherichia coli or Streptococcus faecalis. J. Bacteriol. 91:1744-1749. 1966.-Bacterial protection against intestinal infection by Candida albicans was investigated in chicks with a monoflora of either Escherichia coli or Streptococcus faecalis. These animals were obtained by orally inoculating germ-free chicks (3 days old) with pure cultures of bacteria. Each bacterial species was established in large numbers in the gut of separate groups of animals within 24 hr of inoculation; these numbers were similar in chicks examined 34 days later, at which time all animals were killed. The numbers of bacteria from contents of the crop, small intestine, and ceca were similar in chicks with the E. coli monoflora. Comparable results were obtained in chicks with the S. faecalis monoflora, except for decreased numbers in the duodenum and jejunum. Some of the monoflora chicks (7 days old) were transferred into separate isolators, orally inoculated with C. albicans, and observed for 34 days. All chicks grew well and appeared healthy. However, examinations at autopsy revealed severe crop infections in chicks with a diflora containing S. faecalis. Preferential growth of hyphae (C. albicans) occurred in the lesions and throughout the gut. The numbers of S. faecalis in the gut were comparable to those found in unchallenged animals. Agglutinins against C. albicans were not detected in our test or control chicks. Chicks with a diflora containing E. coli and C. albicans had a few microscopic crop lesions containing small numbers of hyphae. C. albicans was well established in the gut of these animals, largely as the yeast form. The numbers of E. coli in the gut were similar to those in control chicks. Thus, it was concluded that E. coli provided protection against crop infection by C. albicans. In crop contents from unchallenged animals, chicks with S. faecalis monoflora were about pH 5, whereas birds with E. coli monoflora were about pH 7. The challenge did not greatly change the former value, and the latter was slightly decreased. In the crop of unchallenged birds, negative E(h) values were found in chicks with S. faecalis and positive E(h) values in those with E. coli. Challenge did not greatly change these values. These data on pH and E(h) were related to conditions for morphogenesis of C. albicans and virulence. No major difference in the concentrations of serum proteins was seen in chicks with E. coli or S. faecalis after challenge with C. albicans. Possible mechanisms of the protective effect of E. coli are discussed.