NATURE, FORMATION, AND ACTIVITIES 



oofsis group. Such antibiotics can be active 

 against other microorganisms; examples: the 

 macroHdes and the tetraeycHnes. 



7. Antibiotics active against protozoa. 

 Such antil)i()tics usually have other types of 

 antimicrobial activity also. They include 

 paromomycin, which is also active against 

 bacteria, and trichomycin, which is also 

 active against fungi. 



Substances produced by actinomycetes 

 which are not always strictly antibiotics 

 have other types of biological activity: (1) 

 antiviral substances such as ehrlichin, (2) 

 antitumor substances; these may be anti- 

 biotics, such as aetinomycir., or have no 

 known antibiotic activity, such as carcino- 

 mycin. 



The keys and lists in Pai't B of this book 



show in more detail the antibiotics belong- 

 ing to these various groups. 



The antibacterial properties of a group of 

 antibiotics produced by actinomycetes are 

 shown in Table 27, in which the sensitivities 

 of different bacteria are summarized accord- 

 ing to Turpin and Velu (ll)r)7). Streptomy- 

 cin and neomycin show the greatest activity 

 against the mycobacteria and various gram- 

 negative bacteria, especially the Escherichia, 

 Saimonclla, Proteus, and Pseudomonas 

 groups; they show little or no activity 

 against the anaerobic Clostridia, and Km- 

 ited activity against the neisseriae and 

 (•(M'tain streptococci. Erythromycins are 

 highly active upon the various cocci and 

 certain gram-positi\e bacteria, but show 

 only limited action upon gram-negative or- 



Table 27 

 Comparative sensitivity of variouf^ bacteria to several antibiotics cif actinomycetes CTiirpin and Velu, 1957) 

 Re.sults given as ng per ml. 



R = resistant. 



