Samir A. Saheb

Purification and characterization of Treponema hyodysenteriae hemolysin

A hemolysin produced by Treponema hyodysenteriae ATCC27164 was purified from broth filtrates by acetic and (NH4)2SO4 precipitations followed by ion exchange chromatography on diethylaminoethyl-Sephacel and gel filtration using Ultrogel AcA44. The purified hemolysin displayed only one band on polyacrylamide gel electrophoresis. By gel filtration the molecular weight was estimated as 74,000 daltons. The isolated hemolysin was oxygen resistant, heat labile and was not inactivated over a wide range of pH values. Further analysis indicated that this hemolysin was probably a polypeptide or a protein associated with lipids and nucleotides. Its action on rabbit erythrocytes which did not require any divalent cations could not be related to a lipolytic or proteolytic activity.

Characteristics of the interaction of a treponemal hemolysin with rabbit erythrocytes

The mechanism of action on rabbit red cells of Treponema hyodysenteriae hemolysin was studied using volume analysis and release of hemoglobin. While fixation of the hemolysin on the erythrocytes is temperature independent, it appears that hemolysis is temperature dependent. The kinetics of hemolysis proceed according to a sigmoid curve characterized by a prelytic lag. The duration of the prelytic lag varies inversely with the quantity of hemolysin but the rate and the maximum value of hemolysis are directly proportional to the quantity of hemolysin. The effect of sucrose and trypan blue on the hemolysin and the the red cells suggest that erythrocyte lysis is likely to be induced by the hemolysin in a way different from that known for other hemolytic agents.

Comparative study of the hemolysins ofTreponema hyodysenteriae andTreponema innocens

The nucleic acid-bound hemolysins from two strains ofTreponema hyodysenteriae (β-hemolytic) and two strains ofT. innocens (weakly β-hemolytic) were purified and characterized. All four hemolysins shared similar molecular weights, stability to oxygen, and pH and heat lability. The hemolysins were inactivated by pronase and lipase and inhibited by trypan blue. Although lacking detectable proteolytic or phospholipase activity,T. hyodysenteriae andT. innocens hemolysins differ in their sensitivity to phospholipids; the former was insensitive to cardiolipin, which completely inhibited the latter. Furthermore, both groups of hemolysins differed in their hemolytic spectra and in their specific activities on rabbit erythrocytes. The results showed that the observed hemolytic patterns ofT. hyodysenteriae andT. innocens on blood agar were due to different hemolysins.

Effect of culture medium composition on inhibition of growth ofNeisseria gonorrhoeae by lactobacilli

The role of genital microorganisms in resistance to gonococcal infection is usually based on their in vitro inhibition of gonococcal growth. Three different culture media (GC, DSA, and MRS) were evaluated for their ability to support the growth of 23 lactobacilli strains and the detection of the antigonococcal activity of these bacteria. The MRS medium was the most suitable medium for the growth of lactobacilli since it favored a good growth of all the lactobacilli strains tested, but it was inhibitory toNeisseria gonorrhoeae. Decreasing the concentration of Tween 80, ammonium citrate, and sodium acetate to one-tenth of their original concentrations yielded a modified MRS medium which still supported good growth of the lactobacilli and was no longer inhibitory to the gonococci. While GC medium did not allow any detection of the production of antigonococcal activity by the lactobacilli, both modified MRS and DSA media allowed the detection of this activity by the agar overlay technique. The use of modified MRS medium is recommended since it is less selective than DSA medium for the growth of lactobacilli.

Etude comparative des caractères biochimiques de tréponèmes hémolytiques isolés du porc

A number of hemolytic strains of treponemes were isolated from normal pigs and pigs which died of swine dysentery. According to their hemolytic pattern, these strains can be differentiated into str...

Biological activity ofTreponema hyodysenteriae hemolysin

The biological properties ofTreponema hyodysenteriae hemolysin (TH), which in some aspects resembles streptolysin S, were studied. Aside from different erythrocyte species, TH had no lytic activity on prokaryotic (protoplasts and spheroplasts) and eukaryotic (Chinese hamster ovary and spleen) cells. However, TH decreased the response of spleen cells to concanavalin A and lipopolysaccharide. In vivo, TH was found to induce fluid accumulation in ligated rat ileal loops as well as histological modifications similar to those observed in the swine dysentery. These results further differentiate TH from streptolysin S, and suggest that it is a new oxygen-resistant hemolysin produced by a Gram-negative bacterium.

7 – SCREENING OF BACTERIAL ISOLATES FOR ANTIGONOCOCCAL ACTIVITIES

ABSTRACT Of the 213 urogenital bacterial isolates studied, 95 were found to interfere with Neisseria gonorrhoeae growth on solid medium. The selection of inhibitory isolates was primarily based on the specificity of action of the inhibitory substances against N . gonorrhoeae . More than 30 aerobic and anaerobic isolates were active against the majority of the gonococcal strains tested (auxotypes, penicillin resistant and virulent T1) without interfering with many representative bacteria of the normal urogenital flora. Study of the antigonococcal activities produced by Staphylococcus epidermidis No. 7, Micrococcus sp. No. 42, Bacteroides vulgatus B4, Propionibacterium acnes Pr 20 and Eubacterium limosum 9A has shown that they respond entirely or partially to the following criteria: bactericidal, nontoxic, and active in vivo . The screening strategy based on the selection of interfering bacterial isolates of the urogenital flora has resulted in promising antigonococcal activities.