George H. Warren

Effect of Sublethal Concentrations of Penicillins on the Lysis of Bacteria by Lysozyme and Trypsin

Summary Resistance of Staphylococcus aureus and other bacteria to lysis by lysozyme and trypsin is abolished in cultures grown in sublethal concentrations of antibiotics. Antibiotics which inhibit synthesis of the mucopeptide polymer of bacterial cell walls differ widely in their ability to influence the lysis of cell suspensions. Such differences are revealed by both the speed of reduction of turbidity and final level of turbidity reduction. Under the influence of nafcillin, cells of Staphylococcus aureus, Streptococcus faecalis and Diplococcus pneumoniae are readily lysed but Neisseria catarrhalis, Sarcina lutea and Gaffkya tetragena are resistant, suggesting that bacterial cells differ in resistance or susceptibility to enzymic lysis. Lysis is not conditioned by the in vitro antibacterial activity of the antibiotics; nafcillin, which has the same activity against Staphylococcus aureus as oxacillin, cloxacillin, cephalothin, novobiocin and vancomycin, gives a greater rate and extent of lysis than the other antibiotics when used in comparable concentrations. Of the antibiotics interfering with protein synthesis, only erythromycin gives a significant lytic response. The results suggest that sublethal levels of antibiotics may mediate a favorable interplay between the host tissue environment and the parasite.

Effects of Cortisone, Hyaluronidase, Desoxycorticosterone, and Artisone on Experimental Serum Disease in Rabbits:

Conclusions Cortisone in doses of 4 mg twice daily depressed the Arthus reaction in the skin and completely prevented arteritis and carditis in 8 of 9 rabbits treated with horse serum. Glomerular nephritis, on the other hand, was not prevented. The zona fasciculata of the adrenals was atrophied. The mortality rate was highest among the animals receiving cortisone. Hyaluronidase in doses of 6000 T.R.U. per kg depressed the Arthus reaction in the skin and diminished glomerular nephritis, but enhanced arteritis and carditis. These observations may be explained by the ability of hyaluronidase to weaken ground substance barriers, thereby diverting antigen and antibody from the kidneys to the general vascular bed. DCA and Artisone in the doses used had no remarkable effect on the histological manifestations of serum disease, but DCA caused a depression of the Arthus reaction in the skin possibly through its hyaluronidase-like effect upon the ground substance. It appears that serum disease is an excellent experimental tool for comparing the total efficacy of cortisone-like drugs after preliminary screening for their anti-permeability action on ground substance.

PHARMACOLOGY AND DISTRIBUTION OF WY-3277 (NAFCILLIN): 6-(2-ETHOXY-1-NAPHTHAMIDO)PENICILLANIC ACID.

Abstract Studies with nafcillin, a new penicillin synthesized from 6-aminopenicillanic acid, establish it as an antimicrobial agent that is 4–8 times more effective than methicillin against gram-positive cocci, Diplococcus pneumoniae and penicillinase producing strains of Staphylococcus aureus . It is relatively nontoxic for animals over a wide range of doses and provides an adequate margin of safety by all routes of administration. Local tissue responses following intramuscular administration of 25% solutions are minimal and resemble penicillin G rather than methicillin. Assays in dogs for antibiotic levels following single 50 mg/kg doses of nafcillin show that effective serum concentrations occur by all routes of administration and persist through 6 hours. Penetration into the cerebrospinal fluid occurs with difficulty; however, after intravenous injection small amounts are detected for 1 hour. Additional studies indicate that effective amounts are concentrated in the bile, kidney, lung, heart, spleen, and liver. Biliary excretion and reexcretion is an important pathway in the disposition of nafcillin and proceeds at bactericidal levels for a considerable length of time.

Effect of mixtures of atabrine and antibacterial agents on the emergence of resistant strains of Mycobacterium tuberculosis.

THERE have been numerous descriptions of the successful use of mixtures of antibiotics and atabrine in preventing the emergence of resistant strains of Staphylococcus aureus and Escherichia coli1–4. When a sensitive strain of these organisms was subcultured in an antibiotic, however, the mixture of antibiotic and atabrine was no longer effective in eliminating resistance.

Production of a polysaccharide by Staphylococcus aureus. I. Enhancement by penicillins.

Summary A polysaccharide has been isolated from heat-treated or sonically disrupted cells of S. aureus. The polysaccharide is readily attacked by bovine testicular but not by bacterial hyaluronidase. Under the influence of subinhibitory concentrations of penicillin G and nafcillin, the production of the polysaccharide is greatly increased. The possible influence of penicillin on a fundamental pathway or enzyme system involved in the breakdown of the polysaccharide is discussed.

Accumulation of dermal mucopolysaccharides in animals following injection of estradiol benzoate.

Summary Accumulation of mucopolysaccharides in response to estradiol benzoate inoculation in the skin of various rodents was studied. Only white Swiss mice responded with increased accumulation. Rats, guinea pigs, and hamsters did not show this response. Neither age, sex of the animal, nor dose of estradiol had any effect on amount of mucopolysaccharide accumulated. This activity of estradiol was neither effected by castration of males nor reversed by administration of cortisone.

Production of a Polysaccharide by Staphylococcus aureus. III. Action of Penicillins and Polysaccharides on Enzymic Lysis

Summary 1. The resistance of S. aureus to lysis by lysozome and trypsin was abolished by exposing growing cells to subinhibitory concentrations of nafcillin. This observation, together with the results of electron microscopic studies of nafcillin-treated cells exposed to maximal enzymatic action, reflect an actual interference with cell wall synthesis. 2. Although the precise cytological action of the subinhibitory levels of the penicillins on the integrity of the cell wall is not known, the limited lytic action of lysozyme on cells treated with oxacillin and cloxacillin, as well as the resistance of these cells to further lysis by trypsin, suggest at least a quantitative difference between nafcillin and the other penicillins in the disorganization of the cell wall structure. 3. On the basis of the experiments described, evidence is presented which indicates that subinhibitory levels of nafcillin produce an alteration of cell wall structure, thereby increasing permeability and rendering the cell wall and proto-plasmic constituents accessible to the action of lysozyme and trypsin.

PRODUCTION OF A POLYSACCHARIDE BY STAPHYLOCOCCUS AUREUS. II. EFFECT OF TEMPERATURE AND ANTIBIOTICS.

Summary It has been shown that S. aureus grown in the presence of subinhibitory concentrations of nafcillin produced a disturbance or disorganization of the cell wall fabric resulting in a marked accumulation of a polysaccharide within the cell. An appreciable polysaccharide response was also found for oxacillin, methicillin and erythromycin. This conclusion is based on data which demonstrate a clear differentiation between such an inhibitor of bacterial wall synthesis as penicillin which exerted a pronounced effect on polysaccharide synthesis and other antibacterial antibiotics which failed to increase the quantity of polysaccharide formed. In addition, treatment with nafcillin rendered the normally lysozyme resistant cells of S. aureus susceptible to partial lysis by lysozyme and the concomitant addition of trypsin resulted in further dissolution of the cell bodies. Electron micrographs of such treated cells subjected to thermal stress provide further evidence of the relationship between accumulation of polysaccharide and actual interference with cell wall synthesis. The significance of the results relating to the mechanism of action of the semi-synthetic penicillin nafcillin and possibly other penicillins is discussed.

Pathogenicity and Immunogenicity Herpes Simplex Virus Strains Propagated in Rabbit Kidney Tissue.

Summary Four strains of HSV have been propagated in high titer in RK monolayer culture. Marked strain differences exist with regard to cytopathogenic effect as well as virulence for chick embryos, mice and other animals. Tissue culture propagated HSV is much more highly antigenic than the same virus strain grown in the chick embryo.

Production of Polysaccharide by Staphylococcus aureus. IV. Correlation of Lytic Response with Penicillin Activity.

Summary Studies on the effects of sub-inhibitory concentrations of nafcillin, oxacil-lin, and cloxacillin on S aureus supported the view that nafcillin and the isoxazole penicillins may induce important changes in the cell wall during growth that result in increased susceptibility to lysis by lysozyme and trypsin. The observations suggested that significant quantitative differences exist between the ability of nafcillin and the other semisynthetic penicillins to render S. aureus susceptible to enzymic action. The significance of the data is discussed, with particular reference to the possible in vivo effects of subinhibitory concentrations of the penicillins in mediating a favorable interplay between the tissue environment and the parasite.