Bacitracins

The original bacitracin-producing organism was identified as a strain of B. subtilis, but subsequently it was more accurately classified as a variant of B. licheniformis. Recently, however, a bacitracin-producing strain of B. subtilis was reported, and both organisms are therefore mentioned in Table 1.9. 

The only clinically used members of this group are the bacitracins. Bacitracin is further used in veterinary medicine and as a supplement to the diets of animals, particularly farm animals . The subtilins are used in the food industry as preservatives. 

In 1945, a new antibiotic was reported it was produced by a grampositive sporulating bacillus of the B. subtilis group and isolated from cultures of contaminated tissue removed from a fracture of the tibia. This strain was named after the patient Tracey I and the active principle in the cell-free filtrates of broth cultures was therefore called Bacitracin . The antibiotic was first produced in surface cultures Ass a d later by submerged cultures in synthetic media A94. Later the organism was classified as a strain of B. licheniformis. In 1949 another antibiotic from a strain of B. licheniformis, originally called A-5, was described under the name ayfivin A6 . It soon became apparent that bacitracin and ayfivin were closely related in their physical, chemical and biological properties . The name ayfivin was therefore abandoned in favour of bacitracin . 

Commercial bacitracin was resolved by countercurrent distribution into a main component, called bacitracin A, and several other eomponents designated as bacitracin B, D, E and F . Later, another sample of crude 

Best known are the major component bacitracin A, and bacitracin F, an inactivation product of bacitracin A, through the work of Craig and his co-workers, Abraham and Newton and, to a lesser degree, Porath. The molecular weight of bacitracin A was shown by different methods to be about 1,5001 . Total and partial hydrolysis gave evidence of the presence of three L-isoleucine molecules and one each of L-leucine, L-cysteine, i.-histidine, L-lysine, L-aspartic acid, D-phenylalanine, D-ornithine, D-aspartic acid, D-glutamic acid and ammonia in the molecule. 

Johnson et al. (323) described an antibiotic produced by B. subtilis, distinct from subtilin and particularly active against hemolytic Streptococci, and which they called bacitracin. The biological assay, for example the determination of antibiotic activity, has been described by Anker et al. (25) and by Hendlin (268). 

At 37° C., the maximum yield is obtained after 36 liours growth. The best starting pH is between 7.4 and 8.1, and good aeration is necessary. The addition of Mg, Mn, Fe, K, and P is essential for the growth of the bacteria and for production of bacitracin, and Mn is particularly important. 

Extraction of bacitracin from surface cultures has been described by Anker el al. (25). The antibiotic can be extracted from the culture medium with butanol, and concentrated in vacuo, and the colored impurities are adsorbed on MgO. Bacitracin, highly soluble in water, can be precipitated with salicylic acid, can also be lyophilized from aqueous solution, and remains stable for months in the icebox. It can be further fractionated by countercurrent distribution between secondary butanol and 1.7 % aqueous acetic acid (43). The final active product, when lyophilized, is a white hygroscopic powder. One can obtain bacitracin in a crystalline state (143), but thus purified, however, it is not stable (143). 

It was dissolved in ethyl acetate (700 ml) and hydrogenated at ambient conditions over a palladium (5%) on carbon catalyst (18 g). The catalyst was removed by filtration and washed with ethyl acetate. The combined filtrates were extracted with water at pH 2.5 by addition of dilute hydrochloric acid. Lyophilization of the aqueous phase gave the hydrochloride of r-ethoxycarbonyloxyethyl 6-(D-a-aminophenylacetamido)penioillinate (94 g), MP 

Chemical Name Complex polypeptide mixture containing predominantly bacitracin A Common Name — 

Trade Name Manufacturer Country Year Introdi 

Nutrient Medium (Soy Been Oil Meal) Manufacturing Process 

Nutrient Medium (Soy Bean Oii Meai) Manufacturing Process 

---

CONTROLLED RELEASE TECHNOLOGY - PHARMACEUTICAL] (Vol 7) -bacitracin treatment of [ANTIBIOTICS - PEPTIDES] (Vol 3)... 

Zinc bacitracin Zinc bearings Zinc blende... 

Antibiotics. Solvent extraction is an important step in the recovery of many antibiotics (qv) such as penicillin [1406-05-9] streptomycin [57-92-17, novobiocin [303-81-1J, bacitracin [1405-87-4] erythromycin, and the cephalosporins. A good example is in the manufacture of penicillin (242) by a batchwise fermentation. Amyl acetate [628-63-7] or -butyl acetate [123-86-4] is used as the extraction solvent for the filtered fermentation broth. The penicillin is first extracted into the solvent from the broth at pH 2.0 to 2.5 and the extract treated with a buffet solution (pH 6) to obtain a penicillin-rich solution. Then the pH is again lowered and the penicillin is re-extracted into the solvent to yield a pure concentrated solution. Because penicillin degrades rapidly at low pH, it is necessary to perform the initial extraction as rapidly as possible for this reason centrifugal extractors are generally used. 

Egg hatchabihty in chicken bacitracin zinc Egg production in chicken bacitracin methylene disahcylate... 

Antibiotics approved for use as growth enhancers in Hvestock and poultry include bacitracins, bambermycins, Hncomycin [154-21 -2] penicillin [69-53 ] streptomycin [57-92-1], tetracycHnes, tiamulin [55297-95-5] tylosin [1401-69-0] and virginiamycin [11006-76-1] (61). 

Methylene-5,5-disahcyhc acid is produced by heating two parts sahcyhc acid with 1—1.5 parts of 30—40 wt % formaldehyde in the presence of an acid catalyst (33). The resulting product is a mixture of isomers, primarily the 5,5 -isomer and small amounts of low molecular weight polymers. It is used as an intermediate in the production of bacitracin methylenedisahcylate, which is used in a feed supplement to promote growth and as a medicament in swine, feedlot catde, as well as chickens, turkeys, pheasants, and quail. 

Most polymyxin B sold for human use in the United States is in dermatological, otic, and ophthalmic preparations that usually contain one or more other spectmm extending antibacterials such as bacitracin, neomycin sulfate [1404-04-2], C23H4gNg023, linear gramicidin, oxytetracycline [79-57-2],... 

Bacitracin. Bacitracin, a cycHc peptide active against gram-positive bacteria, was discovered in 1943. Bacitracin received dmg certification in 1949 (60—62). Whereas human usage of bacitracin is almost exclusively topical, the vast majority of bacitracin manufactured worldwide is used as an animal feed additive. Reviews of work on bacitracin include its chemistry (63—67), comprehensive aspects (62), medical aspects (62,68), biosynthesis on large enzyme complexes and genetics (69—71), and production (71,72). 

Bacitracin is produced and marketed as a mixture of at least nine water-soluble peptides. The principal (60 —80%) component is bacitracin A [22601-59-8], C33H2Q3N2y02gS. The most probable stmcture of bacitracin A is shown in Figure 1 (67,73). Bacitracin B [1402-99-9] is similar to bacitracin A except that one of the isoleucines of bacitracin A is replaced by a valine. Bacitracin F [22601-63-4], is a relatively inactive degradation... 

One unit of bacitracin USP is defined as the activity given by 26 micrograms of the dried FDA master standard. The USP requirement for commercial bacitracin is a potency of at least 40 units per milligram in a bioassay with Micrococcusflavus or Sarcina lutea. Pure bacitracin A has a potency of about 100 units per milligram. Standards for animal feed grades of bacitracin are available (71,81,82) as are analytical methods (67). 

Bacitracin given parenteraHy is sufftciendy nephrotoxic that it is rarely used in human medicine for other than topical indications (80). Thus safe and effective use, especially as the zinc salt, is limited almost completely to ointments, sprays, and solutions for skin and ophthalmic use in concentrations of 250 to 1000 units per milliliter. Bacitracin is only rarely skin sensitizing. As in the case of polymyxin, bacitracin is usually combined with other antibiotics to enlarge its spectmm of activity, or with corticoids or analgesics to reUeve pain or itching. 

In the United States, 100 times more bacitracin by weight is used as a feed additive than for human medicine. Most of this is BMD but some is the zinc salt. BMD can be used in subtherapeutic nutritional dosages for increase in feed efficiency and for growth promotion in poultry, swine, and feedlot cattie at concentrations of 2.6—33 g/t of feed (78,81,82). Prophylactic or therapeutic medicinal dosing at higher concentrations is used for necrotic enteritis in chickens, transmissable enteritis in turkeys, ulcerative enteritis in quail, dysentery in swine, and Hver abcess in cattie (see Feeds and feed additives). 

---