THE MICROBIOTICS — MCDONNELL 451 



TYROTHRICIN 



Tyrothricin, the combination of gramicidin and tyrocidine, is a 

 highly complex chemical of varying composition obtained from cul- 

 tures of the aerobic, spore-forming soil bacteria, Bacillus brevis strain 

 BG. Its chemical structure is C^HssNgOn or C74H106N14O19. Avail- 

 able as a commercially marketed product, it is used in diluted isotonic 

 solution by instillation, irrigation, or wet dressing. It may be intro- 

 duced into the body cavities such as the pleural cavity, sinuses, mas- 

 toid, and urinary bladder. It is exceedingly toxic in the blood- 

 stream and is not indicated for parenteral injection or oral use. 

 Tyrothricin has been found to be of particular value in treatment of 

 indolent ulcers, abscesses of skin and mucosa, mastoiditis, certain in- 

 fections of eye, nasal sinus, and pleural cavity, empyema, postopera- 

 tive infections, and osteomyelitis. It has been found most effective 

 against certain species of staphylococci, streptococci, and similar 

 organisms. 



GLIOTOXIN 



Gliotoxin was crystallized several years ago, before penicillin, from 

 Gliocladium fimbriatum, Aspergillus fumigatus, and Trichoderma 

 species. It is effective against both gram-positive and gram-negative 

 organisms but is too toxic for therapeutic use. Its chemical formula 

 is Ci 3 H 14 04N 2 S 2 . Gliotoxin has been found to be effective against the 

 staphylococci, streptococci, and Biplococeus pneumoniae. 



FUMAGACIN, FUMAGATIN, AND ASPERGILLIC ACID 



Aspergillic acid is a substance derived from Aspergillus flavus, hav- 

 ing the chemical structure of Ci 2 H 20 N 2 O 2 without sulfur in the mole- 

 cule. It has a limited range of effectiveness against both gram- 

 positive and gram-negative bacteria. 



Fumagacin, or helvolic acid as it is also called, is similar in action 

 to penicillin. It has an indefinite chemical formula with either 32 or 

 53 carbon atoms, and is lacking in both nitrogen and sulfur. Being 

 water-insoluble in nature and less active, it is less valuable even 

 though it is generally effective against gram-positive organisms, sim- 

 ilar to the action of penicillin. It is derived from Aspergillus fumi- 

 gatus. Also obtained from the same organism is fumagatin, C 8 H 8 4 , 

 which has limited sensitivity and therapeutic value. 



OTHER KETONE COMPOUNDS 



These ketone antibiotic compounds have been crystallized and ob- 

 tained in pure form. Several others are of lesser significance, such 



