Action of microbe-antagonists on bacilli and corynebacteria of the skin of the breast in nursing women

Five microbes-antagonists are studied for their inhibitory action on 769 strains of bacilli (241) and corynebacteria (528) isolated from the mammary gland skin of 120 nursing women on the 2nd-5th day after labour. Escherichia coli M-17 and Mycococcus krassilinikovi are established to possess the highest antagonistic properties against the spore-bearing aerobic and coryneform bacteria. Bifidobacterium bifidum has exerted a moderate antagonistic action on the culture under study, Bacillus subtilis has exerted a strong inhibitory action on corynebacteria. B. licheniformis has slightly inhibited the both bacterial groups.     

Antagonistic activities of coagulase-positive staphylococci

Antagonistic activities were investigated by Frédérioq's plate method in 1,014 coagulase-positive staphylococcal strains of different species and origins. Staphylococcin effect was demonstrated in 12 (2%) of the 559 Staphylococcus aureus strains, in 51 (18%) of the 283 S. intermedius strains, and in 1 (3%) of the 36 S. hyicus subsp. chromogenes strains. Lysostaphin was identified in the 15 (5%) S. intermedius strains. In addition, heat-stable bacteriostatic agent was detected in 45 (33%) and heat-labile bacteriolytic agent in 7 (5%) of the 136 S. hyicus subsp. hyicus strains. An attempt was made at antagonistic activity typing in all of the active staphylococcal strains.     

Antagonistic action of Pseudomonas aeruginosa against Staphylococci, coliform bacilli and various types of Proteus

Antagonistic activity of 2 fresh isolates and 3 collection strains of Pseudomonas aeruginosa against 177 microbial strains was determined with the method of late antagonism. Among the microbial strains there were 56 staphylococcal strains isolated from patents and carriers. 38 nontypable colon bacilli isolated from healthy persons, 59 enteropathogenic colon bacilli of various serogroups, 12 strains of Proteus and 12 colon bacilli, carriers of multiple drug resistance factors (R factors). All the cultures were sensitive to the antagonistic action of 5 or at least 3 strains of Pseudomonas used in the study. The most active antagonists were the fresh isolates of Pseudomonas as compared to the collection strains. Among the staphylococci S. aureus proved to be the most resistant to the antagonistic action of Pseudomonas as compared to S. epidermidis, the same as the strains isolated from carriers as compared to the strains isolated from patients. As for the enteric bacilli the most resistant were the strains of Proteus. Acquiring of transmissive R factors by the colon bacilli markedly increased their sensitivity to the antagonistic action of Pseudomonas.     

Bacteriostatic action of progesterone on staphylococci and other microorganisms

Yotis, William (Loyola University, Hines, Ill.), and Ronald Stanke. Bacteriostatic action of progesterone on staphylococci and other microorganisms. J. Bacteriol. 92:1285-1289. 1966.-Progesterone has been examined in vitro for antibacterial activity against 10 microorganisms. Turbidimetric and manometric techniques were used to assay the antibacterial activity of progesterone. The organisms tested consisted of Staphylococcus aureus, S. epidermidis, Gaffkya tetragena, Bacillus subtilis, Listeria monocytogenes, Candida albicans, Escherichia coli, Aerobacter aerogenes, Salmonella paratyphi, and Proteus vulgaris. Antibacterial action was shown by progesterone only against the gram-positive microorganisms when they were grown in tryptic soy broth containing 10 to 20 mug of progesterone per ml. Pregnenolone, 4-pregnen-20beta-ol-3-one, and 5alpha-pregnane also possessed antistaphylococcal properties, whereas pregnanolone, pregnandione, 11alpha-hydroxyprogesterone, and 17alpha-hydroxyprogesterone did not. The bacteriostatic action of progesterone on staphylococci was exerted primarily during the first 8 hr of incubation, and it was reduced in the presence of oxygen. In the presence of 20 mug of progesterone per ml, there was significant reduction in the oxidation by resting staphylococcal suspensions or utilization by staphylococci of pyruvate as an energy source during growth.     

Production of antibacterial substances by resident corynebacteria isolated from human skin

Coryneform bacteria, especially lipophilic species, form stable but not dominant population on a human skin. This position is probably controlled by secretion of bacteriocin-like substances, which act directly on coexisting bacteria. Among 118 investigated corynebacteria belonging to seven species/taxa and isolated from human skin, 90% possessed an ability to produce such substances. The spectrum of their activity was restricted to killing gram-positive bacteria, but along with corynebacteria it also covered cocci, with Staphylococcus aureus in this group. This feature was revealed better on low pH media (pH 5.6) and media with 1.5% NaCl for cocci, but on pH 7,4 for corynebacteria.     

Bacteriostatic and bactericidal action of bile acids and antibiotics on staphylococci

It was found in vitro that desoxycholic, cholic, glycocholic and choleinic acids inhibited the growth and development of staphylococci. The staphylococci isolated from bile were more resistant to the bacteriostatic and bactericidal effect of bile acids than the microorganisms isolated from other sources not containing cholates. Under the effect of these substances the activity of some antibiotics especially those from the group of aminoglycosides markedly increased.     

Lethal action of ribonuclease for thermophilic bacilli

Thompson, T. L. (University of Nebraska, Lincoln), and J. M. Shively. Lethal action of ribonuclease for thermophilic bacilli. J. Bacteriol 91:673-676. 1966.-Exposure of a thermophilic bacillus, NU 47, to 0.2 mug/ml of pancreatic ribonuclease resulted in a drastic reduction of viable cells. The observed lethality is thought to be associated specifically with the ribonuclease, since heat treatment did not diminish activity and the addition of ribonucleic acid to the cells completely eliminated the action of the enzyme. Cells from 2-hr cultures, buffered between pH 6.0 and 7.0, were most sensitive. The lethal action was most pronounced when cells were exposed to the enzyme at temperatures between 25 and 45 C. A greater proportion of cells survived at higher temperatures. The release of ultraviolet-absorbing materials into the medium after exposure to enzyme could not be detected.