Chemical properties of the principle in C. parvum that produces splenomegaly in mice

Suspensions of Wellcome C. parvum strain 6134 produce splenomegaly in mice when injected i.p. in amounts as low as 20 microgram. This lymphoreticular stimulatory activity is extremely sensitive to cell breakage and is abolished by heating for 4 h at 100 degrees. Periodate oxidation of the bacteria destroys their capacity to produce splenomegaly and abrogates the agglutination of intact C. parvum by Con A. Mild HCl hydrolysis also abolished the splenomegaly but phenol:chloroform:ether and chloroform:methanol extractions did not. These results suggest that the relevant stimulatory principle in C. parvum is of carbohydrate nature, and most probably present on the surface of the bacterium.

Selective antibacterial action of 2-mercaptoethanol on propionibacteria in skin cultures

2-Mercaptoethanol applied to the surface of agar medium had a selective antibacterial effect on Propionibacterium acnes and Propionibacterium granulosum without interfering with the growth of Peptococcus saccharolyticus or staphylococci in anaerobic cultures of skin or in pure cultures. In aerobic broth culture, 2-mercaptoethanol inhibited aerobes and stimulated anaerobes, consistent with its action as a reducing agent.

Low trimethoprim susceptibility of anaerobic bacteria due to insensitive dihydrofolate reductases

All the 28 Bacteroides fragilis strains investigated were susceptible to sulfamethoxazole (minimal inhibitory concentration < 16 mug/ml) and resistant to trimethoprim (TMP; minimal inhibitory concentration > 4 mug/ml). Synergism between sulfamethoxazole and TMP was present in all strains at a ratio of 1:1. The few clostridia investigated proved more resistant to both compounds. Dihydrofolate reductases from B. fragilis, C. perfringens, and some other anaerobic species were isolated. Inhibition profiles with six structurally different inhibitors revealed major differences in all enzymes. For 50% inhibition, the enzyme from B. fragilis and all clostridia required concentrations of TMP which were between several hundredfold and 1,000-fold higher than those required for the enzyme of Escherichia coli, whereas the enzyme from Propionibacterium acnes only needed a threefold higher concentration. In vitro activities of TMP were seen to correspond to the activity at the enzymatic level in B. fragilis and P. acnes, but correspond to a much lesser extent to the activity at the enzymatic level in clostridia, where a poor penetration is assumed to be involved. Dihydrofolate reductase inhibitors other than TMP were found to be as active as TMP both at the enzyme and in vitro. In B. fragilis, higher concentrations of exogenous thymidine were required for increasing the minimal inhibitory concentration of TMP than in E. coli and probably also in C. perfringens.

Differential susceptibility of Propionibacterium acnes, P. granulosum and P. avidum to free fatty acids

The susceptibility of 98 Propionibacterium acnes, P. granulosum and P. avidum strains isolated from acne cases and appropriate reference strains to decanoic, dodecanoic, octadeca-9,12 dienoic, and octadeca-9,12,15 trienoic acids was investigated using minimal inhibitory concentration estimation by an agar dilution techique. The tested acids showed their relative antibacterial activity in the following order: C18:3 delta 9,12,15 greater than C18:2 delta 9,12 greater than C12:0 greater than C10:0 Differences between minimal inhibitory concentration values for P. acnes, and P. avidum versus P. granulosum strains were demonstrated in the cases of octadeca-9,12 dienoic, and octadeca-9,12,15 trienoic acids.

Effect of topical application of dexamethasone on Propionibacteria in the pilosebaceous duct

A preparation of dexamethasone 0.02% in Eutanol G (n octyldodecanol) was applied once daily for three weeks, to the right side of the forehead of 25 male healthy test subjects. Eutanol G without dexamethasone was applied in the same way to the left side of the forehead. Before and at the end of the treatment period bacteria were removed from the pilo-sebaceous ducts by the method of Holland et al. [8]. Bacteria that grew under anaerobic conditions were evaluated quantitatively. Dexamethasone induced a significant increase in P. acnes, in all Propionibacteria and in the total bacterial count. The importance of these findings is discussed in relation to the development of steroid acne.

In vitro activity of tiamulin (81.723 HFU), a new pleuromulin derivative, against clinically significant anaerobes

The susceptibility of more than 40 strains of Gram-negative and Gram-positive anaerobes to tiamulin (Sandoz 81.723 hfu), a new pleuromulin (pleuromutilin) derivative, was determined by broth dilution and agar dilution tests. The influences of density of the inoculum upon MICs was studied by a specially designed pour plate-technique. Bacteroides fragilis, B. vulgatus, B. splanchnicus, B. oralis, B. asaccharolyticus, B. melaninogenicus, Fusobacterium fusiforme (F. nucleatum), Sphaerophorus necrophorus, Clostridium perfringens, C. fallax, Propionibacterium acnes and several species of Peptococcaceae showed broth dilution MICs of 0.03 similar to 1 microgram/ml. Members of B. thetaiotaomicron, B. distasonis and S. freundii (F. mortiferum) were inhibited by 8 similar to 32 microgram/ml and 2 strains of S. varius had a broth dilution MIC of 256 microgram/ml. With most strains, the agar dilution MICs were 2 similar to 4 similar to 8 times the broth dilution MICs. In pour plate-tests, the MICs were not considerably influenced influenced by varying initial concentrations of viable cells. With most anaerobes, the MBCs of tiamulin were more than 100-fold higher than the MICs. The results obtained indicated that, apart from S. varius, B. thetaiotaomicron, B. distasonis and S. freundii (F. mortiferum), members of 16 other anaerobic species including B. fragilis were without exception sensitive to tiamulin.

Susceptibility of Propionibacterium acnes to seventeen antibiotics

The in vitro susceptibility of 96 isolates of Propionibacterium acnes to 17 antibiotics was determined by utilizing an agar dilution technique. With the exception of the aminoglycosides, these organisms are susceptible to virtually all of the commonly used antimicrobial agents.

Immunological properties of Propionibacterium acnes. I. Potentiation and Suppression on antibody response to sheep and hamster erythrocytes in mice

Adjuvant activity of phenol-treated cells of Propionibacterium acnes C-7 in antibody response was investigated in ICR mice. Simultaneous administration (day 0) of P. acnes (i.p.) and sheep red blood cells (SRBC) (i.v.) enhanced the formation of direct plaque-forming cells (PFC) on days 2, and the formation of indirect PFC response on day 7 and thereafter. Conversely, pretreatment from 11 to 14 days before antigen injection suppressed markedly the antibody response. The potentiation and the suppression of immune response depended on doses of antigen and of P. acnes, the timing of adjuvant injection and the time of assay. The two opposite phenomena caused by P. acnes were also confirmed in antibody response against hamster red blood cells (HRBC). Pretreatment with P. acnes 1 to 14 days before antigen injection suppressed markedly anti-HRBC antibody response, whereas P. acnes injected simultaneously with HRBC or one day after injection of the antigen induced prolongation of antibody response and the production of 2-mercaptoethanol-resistant antibody.

Antimicrobiol susceptibility of Propinibacterium acnes and related microbial species

The minimal inhibitory concentrations of 32 antimicrobial agents were established for 73 strains of Propionibacterium acnes and four related species (P. granulosum, P. avidum, Corynebacterium minutissimum, and C. parvum). Most strains showed good susceptibility to those agents usually considered active against gram-positive organisms. With the exception of C. minutissimum, the strains tested revealed more or less identical susceptibility ranges. The lowest minimal inhibitory concentrations were observed with benzylpenicillin, ampicillin, cephalothin, rifampin, erythromycin, clindamycin, and minocycline. C. minutissimum was more susceptible to gentamicin, sisomicin, tobramycin, and fusidic acid but more resistant to most other drugs than were the other species examined.

Antibiotic resistant acne

Our approach to a patient who fails to respond to antibiotics is as follows: First, take a careful history. Look for use of cosmetics and topical corticosteroids, anticonvulsive agents and systemic corticosteroids. Inquire about marked increases in emotional or psychological stresses accompanied by noticeable seborrhea. Probe the patient about habits of leaning on or squeezing acne areas, and most importantly, inquire how often and in what manner the patient washes. In the physical examination, look for evidence of sinus tract formation--extending, tunneling lesions with openings to the surface. Use Wood's light examination for the density of follicular fluorescence to rule out failure to properly absorb an antibiotic; fluoresce the oral mucosa to rule out failure to comply when the antibiotic is a tetracycline. Culture the surface aerobic flora on routine media with and without the antibiotic in question to settle any question of malabsorption. A systematic approach to these possibilities will usually uncover the factor or factors responsible for therapeutic failure. Clinical improvement promptly follows, once proper measures are initiated to neutralize the aggravating forces.

Topically applied antibiotics in acne vulgaris: clinical response and suppression of Corynebacterium acnes in open comedones

Topical antibiotics were used on patients with acne vulgaris. Corynebacterium acnes organisms from open comedones were quantitated during treatment, and the progress of the disease was evaluated. Clindamycin lotion completely suppressed the growth of C acnes organisms, whereas erythromycin and tetracycline did not depress the C acnes counts. Taken as a group, these antibiotics gave a substantial improvement of the disease on the treated side as compared with paired untreated sides of the face and back.

Anaerobic and aerobic skin bacteria before and after skin-disinfection with chlorhexidine: an experimental study in volunteers

The amount, composition, and localization of anaerobic and aerobic bacteria in the normal skin before and after disinfection were the subject of a volunteer study. The superficial bacterial flora were sampled by velvet pad imprints, and the deep flora were determined from whole skin biopsies. Only one anaerobic species, Propionebacterium acnes, was encountered even though other and more strict anaerobic bacteria could have been grown with the anaerobic technique employed. Staphylococcus albus dominated among the aerobic superficial bacteria, while diphtheroids, Micrococcus spp., and lactobacilli occurred sporadically. The deep aerobic bacteria were present in a significantly greater amount than the anaerobic. A two-step cleansing/disinfection procedure was evaluated in vivo in volunteers as well as in surgical patients, and aqueous cetrimide/chlorhexidine (Savlon) followed by chlorhexidine in alcohol (Hibitane) almost eradicated both the superficial and deep anaerobic and aerobic skin flora.