Microbial Sources of Selected Antibiotics

Microorganisms	Antibiotic
Gram-positive rods
Bacillus brevis	Tyrothricin
B. subtilis	Bacitracin
B. polymyxa	Polymyxin
Actinomycetes
Norcardia lurida	Ristocetin
Streptomyces nodosus	Amphotericin B
S. venezuelae	Chloramphenicol
S. aureofaciens	Chlortetracycline & tetracycline
S. erythaeus	Erythromycin
S. fradiae	Neomycin
S. kanemyceticus	Kenamycin
S. griseus	Streptomycin
S. noursei	Nystatin
S. rimosus	Oxytetracycline
Micromonospora purpurea	Gentamicin
Fungi
Arachniotus aureus	Aranotin
Cephalosporium spp.	Cephalothin
Penicillium griseofulvum	Griseofulvin
P. notatum	Penicillin

Selected Bacteriocins

Bacteriocin	Produced by	Bactericidal to
Lactacin F	Lactobacillus acidophilus	Enterococcus faecalis
Lactocin S	L. sake	Gram-positive bacteria
Plantacin	L. plantarum	Inhibits endospore germination
Mesenterocin 5	Leuconostoc mesenteroides	Listeria monocytogenes
Pediocin	Pediococcus acidilactici	Gram-positive bacteria; inhibits endospore germination
Hiraecin S	Enterococcus hirae	Listeria monocytogenes
Propionicin	Propionibacter thoenii	Gram-negative bacteria
Epidermin	Staphylococcus epidermidis	Bacterial skin infections

Mechanisms of Action of Selected Antimicrobials

Antibacterial Drugs	Mechanism of Action
Natural penicillins	Inhibit cell wall synthesis
Semisynthetic penicillins	-
Aztreonam	-
Cephalosporins	-
Imipenim	-
Bacitracin	-
Vancomycin	-
Ethambutol	-
	Interfere with protein synthesis
Streptomycin	Bind 30S ribosome
Tetracyclines	Interfere with attachment of tRNA to mRNA-ribosome comples
Chloramphenicol	Binds to 50S portion to inhibit peptide bond formation
Erythromycin	Bind to 50S portion to prevent translocation
Polymyxin B	Injures plasma membrane
	Inhibit nucleic acid synthesis
Rifamycin	Inhibit RNA synthesis
Quinolones	Inhibit DNA gyrase
-	Competitive inhibitors
Sulfonamides	Inhibit folic acid synthesis
Antifungal Drugs
Amphotericin B	Combine with sterols in plasma membrane
Imidazoles	Interfere with sterol synthesis
Griseofulvin	Inhibits microtubule formation
Tolnaftate	Unknown
Flucytosine	Inhibits DNA and RNA synthesis
Antiviral Drugs
Amantadine	Blocks entry and uncoating
Nucleoside analogs	Inhibit DNA or RNA synthesis
Enzymes inhibitors	Block reverse transcriptase or viral protease
Interferons	Inhibit spread of virus to new cells
Antiprotozoan Drugs
Chloroquine	Intercalates in DNA
Diiodohydroxyquin	Unknown
Metronidazole	Damages DNA
Antihelminthic Drugs
Niclosamide	Inhibits ATP production in mitochondria
Praziquantel	Alters membrane permeability
Mebendazole	Disrupts microtubules
Pyantel pamoate	Neuromuscular block