Microbiological characterization of everninomicins B and D

Area of Science:

• Microbiology
• Pharmacology
• Antibiotic Discovery

Background:

• Everninomicins B and D are antibiotic compounds produced by Micromonospora.
• These antibiotics are part of a complex of antimicrobial substances.

Purpose of the Study:

• To evaluate the in vitro activity of Everninomicins B and D.
• To compare their potency against common antibiotics like penicillin G and chloramphenicol.
• To assess the development of resistance and cross-resistance to these compounds.

Main Methods:

• In vitro susceptibility testing against various bacterial strains including gram-positive bacteria, Neisseria, and Bacteroides.
• Determination of bacteriostatic activity.
• Laboratory selection of resistant mutants from susceptible staphylococci.
• Assay of antimicrobial activity under varied conditions (media, growth, inoculum size, serum presence).

Main Results:

• Everninomicins B and D demonstrated high in vitro activity against gram-positive bacteria, Neisseria, and Bacteroides.
• Activity was greater than chloramphenicol but less than penicillin G against susceptible strains.
• Compounds were bacteriostatic, except against group A streptococci; no activity against facultative anaerobic gram-negative bacilli.
• Resistant mutants were difficult to select and showed no cross-resistance to existing antimicrobial agents.
• Antibacterial activity was reduced by serum or increased inoculum size.
• Everninomicin B was more potent against gonococci and group A streptococci; Everninomicin D was more potent against enterococci.

Conclusions:

• Everninomicins B and D possess significant in vitro antibacterial activity.
• The difficulty in selecting resistant mutants suggests a low propensity for resistance development.
• Their high activity and lack of cross-resistance warrant further investigation as potential therapeutic agents.