Patent Publication Number: US-4548924-A

Title: Antibiotics M43B and M43C, pharmaceutical composition and method of use

Description:
SUMMARY OF THE INVENTION 
     Antibiotics M43B and M43C are new glycopeptide antibiotics produced by Nocardia orientalis NRRL 2452 and NRRL 2450. Antibiotics M43B and M43C and their salts have excellent activity against gram-positive microorganisms. 
     DETAILED DESCRIPTION 
     This invention relates to two new antibiotics called M43B and M43C, and to their salts. M43B has structural formula 1: ##STR1## 
     M43C has structural formula 2: ##STR2## 
     Antibiotics M43B and M43C and their salts have excellent antibacterial activity. The pharmaceutically acceptable salts of M43B and M43C are especially useful. 
     New, improved antibiotics are continually in demand, particularly for the treatment of human diseases. Increased potency, expanded spectrum of bacterial inhibition, increased in vivo efficacy, and improved pharmaceutical properties (such as greater oral absorption, higher blood or tissue concentrations, longer in vivo half life, and more advantageous rate or route of excretion and rate or pattern of metabolism) are some of the goals for improved antibiotics. 
     In the search for new antibiotics, structural modification of known antibiotics is attempted whenever possible. This approach is limited, however, to modifications which retain the desired activity. Many antibiotics, including the glycopeptides, have such complex structures that even small changes can be difficult to make by chemical means. The discovery of new antibiotics produced by fermentation processes continues, therefore, to be of great importance even in cases where the antibiotic, once recognized, is quite similar to a previously known antibiotic. 
     Antibiotics M43B and M43C are newly discovered members of the glycopeptide group of antibiotics. Closely related members of this group include vancomycin (see, for example, U.S. Pat. No. 3,067,099), ristocetin, antibiotic A51568 factors A and B (see the copending applications of M. M. Hoehn and G. G. Marconi, Ser. No. 562,255 filed Dec. 16, 1983 and LaVerne D. Boeck et al., Ser. No. 561,008, filed Dec. 13, 1983). 
     In U.S. Pat. No. 3,067,099, McCormick et al. described the preparation of vancomycin. Three strains of Streptomyces orientalis, two of which were numbered M43-05865 and M5-18260, were disclosed as being capable of making vancomycin. The cultures were deposited at what was then the Northern Regional Research Laboratories at Peoria, Ill., and were given the accession numbers NRRL 2450 (M43-05865) and 2452 (M5-18260). Later, the organism designation for the strains was changed from Streptomyces orientalis to Nocardia orientalis. 
     The vancomycin described in U.S. Pat. No. 3,067,099 became an important, commercially available antibiotic. The N. orientalis culture used to prepare commercial product was N. orientalis strain M5-18260 (NRRL 2452) or its progeny. 
     The structure of a closely related derivative of vancomycin was determined by Sheldrick et al [G. M. Sheldrick, P. G. Jones, O. Kennard, D. H. Williams and G. A. Smith, Nature 271 (5642), 223-225 (1978)]; later, the structure of vancomycin itself was found by Harris et al. [C. M. Harris and T. M. Harris, J. Am. Chem. Soc. 104, 4293-4295 (1982)] to be that shown in formula 3: ##STR3## 
     This invention relates to the discovery of antibiotic M43B and M43C, which are minor factors produced by the N. orientalis M5-18260 (NRRL 2452) strain. The antibiotic complex produced by N. orientalis M43-05865 (NRRL 2450), which is called the M43 antibiotic complex, appears to contain trace amounts of antibiotics M43B and M43C. Methods of making antibiotics M43B and M43C by fermentation of N. orientalis NRRL 2450 are described in the copending application of M. M. Hoehn and R. Nagarajan entitled METHODS FOR PRODUCING M43 ANTIBIOTICS, Ser. No. 600,728, filed herewith this even date. 
     In addition to vancomycin, the M43 complex contains another major factor which is the subject of a copending application of Harvey M. Higgins, Mack H. McCormick and Kurt E. Merkel entitled ANTIBIOTIC M43A, Ser. No. 600,729, filed herewith this even date, and a number of minor factors. Among the other minor M43 factors are (1) A51568 factor A of Hoehn et al., supra, and possibly A51568 factor B of Boeck et al., supra; (2) antibiotic M43D, which is the subject of a copending application of Kurt E. Merkel entitled ANTIBIOTIC M43D, Ser. No. 600,725, filed herewith this even date; and (3) the compounds designated agluco-A51568A, aglucovancomycin and agluco-M43A, and possibly desvancosaminevancomycin, all of which are disclosed in the copending application of R. Nagarajan and A. Schabel entitled NOVEL GLYCOPEPTIDE ANTIBIOTICS, Ser. No. 600,727, also filed herewith this even date. The structural relationships of the M43 antibiotics are provided in formulas 1-12 which follow: 
     
         __________________________________________________________________________
 ##STR4##                                                                 
                              ##STR5##                                    
Compound No.                                                              
        Compound       R  R.sub.1                                         
                             R.sub.2                                      
                                R.sub.3                                   
                                     n  R.sub.4                           
__________________________________________________________________________
1       M43B           CH.sub.3                                           
                          CH.sub.3                                        
                             CH.sub.3                                     
                                COOH 1 vancosaminyl-Oglucosyl             
2       M43C           CH.sub.3                                           
                          CH.sub.3                                        
                             CH.sub.3                                     
                                CONH.sub.2                                
                                     1 glucosyl                           
3       Vancomycin     H  H  CH.sub.3                                     
                                CONH.sub.2                                
                                     1 vancosaminyl-Oglucosyl             
4       M43A           CH.sub.3                                           
                          CH.sub.3                                        
                             CH.sub.3                                     
                                CONH.sub.2                                
                                     1 vancosaminyl-Oglucosyl             
5       M43D           H  CH.sub.3                                        
                             CH.sub.3                                     
                                CONH.sub.2                                
                                     1 vancosaminyl-Oglucosyl             
6       Agluco-A51568A H  H  H  CONH.sub.2                                
                                     1 H                                  
7       Aglucovancomycin                                                  
                       H  H  CH.sub.3                                     
                                CONH.sub.2                                
                                     1 H                                  
8       Agluco-M43A    CH.sub.3                                           
                          CH.sub.3                                        
                             CH.sub.3                                     
                                CONH.sub.2                                
                                     1 H                                  
9       Desvancosamine-A51568A                                            
                       H  H  H  CONH.sub.2                                
                                     1 glucosyl                           
10      Desvancosamine-Vancomycin                                         
                       H  H  CH.sub.3                                     
                                CONH.sub.2                                
                                     1 glucosyl                           
11      A51568A        H  H  H  CONH.sub.2                                
                                     1 vancosaminyl-Oglucosyl             
12      A51568B        H  H  H  CONH.sub.2                                
                                     2 vancosaminyl-Oglucosyl             
__________________________________________________________________________
 
    
     M43B and M43C, the new glycopeptide antibiotics of this invention, are close to vancomycin in structure and also in activity. They are, therefore, valuable additions to this group of antibiotics. 
     M43B and M43C are shown in formulas 1 and 2 as zwitterions. Those in the art will recognize, however, that each has one or two carboxyl groups, one or two amino groups and three phenolic groups which can react to form various salts. All such forms of M43B and M43C are part of this invention. The salts are useful, for example, for separating and purifying the antibiotics. In addition, the salts have an improved solubility in water. 
     M43B and M43C salts are prepared using standard procedures for salt preparation. For example, the M43B zwitterion can be neutralized with an appropriate acid to form an M43B acid addition salt. 
     The acid addition salts of M43B and M43C are particularly useful. Representative suitable salts include those salts formed by standard reactions with both organic and inorganic acids such as, for example, sulfuric, hydrochloric, phosphoric, acetic, succinic, citric, lactic, maleic, fumaric, cholic, pamoic, mucic, D-glutamic, d-camphoric, glutaric, glycolic, phthalic, tartaric, formic, lauric, stearic, salicylic, methanesulfonic, benzenesulfonic, sorbic, picric, benzoic, cinnamic and like acids. 
     Pharmaceutically acceptable acid addition salts are an especially preferred group of salts of this invention. 
     Antibiotics M43B and M43C are prepared by culturing Nocardia orientalis NRRL 2450 or NRRL 2452, or an M43B or M43C-producing variant, mutant or recombinant thereof, under submerged aerobic conditions in a suitable culture medium until a substantial amount of M43B or M43C is produced. The culture medium used to grow Nocardia orientalis NRRL 2450 or NRRL 2452 can be one of a number of media. For economy in production, optimal yield, and ease of product isolation, however, certain culture media are preferred. Thus, for example, preferred carbon sources include carbohydrates such as dextrin, dextrose, glucose and glycerol. Preferred nitrogen sources include enzyme digests of casein, cottonseed meal, soybean grits, protein peptones and the like. Among the nutrient inorganic salts which can be incorporated in the culture media are the customary soluble salts capable of yielding iron, potassium, sodium, magnesium, calcium, ammonium, chloride, carbonate, sulfate, nitrate, and like ions. 
     Essential trace elements necessary for the growth and development of the organism should also be included in the culture medium. Such trace elements commonly occur as impurities in other constituents of the medium in amounts sufficient to meet the growth requirements of the organism. It may be necessary to add small amounts (i.e. 0.2 ml/L) of an antifoam agent such as polypropylene glycol (M.W. about 2000) to large-scale fermentation media if foaming becomes a problem. 
     For production of substantial quantities of antibiotics M43B and M43C, submerged aerobic fermentation in tanks is preferred. Small quantities may be obtained by shake-flask culture. Because of the time lag in antibiotic production commonly associated with inoculation of large tanks with the spore form of the organism, it is preferable to use a vegetative inoculum. The vegetative inoculum is prepared by inoculating a small volume of culture medium with the spore form or mycelial fragments of the organism to obtain a fresh, actively growing culture of the organism. The vegetative inoculum is then transferred to a larger tank. The medium used for the vegetative inoculum can be the same as that used for larger fermentations, but other media can also be used. 
     N. orientalis NRRL 2450 and NRRL 2452 can be grown at temperatures between about 25° and about 37° C. Optimum antibiotic production appears to occur at temperatures of about 30° C. 
     As is customary in aerobic submerged culture processes, sterile air is bubbled through the culture medium. For efficient antibiotic production the percent of air saturation for tank production should be about 50% or above (at 30° C. and about 5 psi of back pressure). 
     Antibiotic production can be followed during the fermentation by testing samples of the broth against organisms known to be sensitive to the antibiotics. One useful assay organism is Staphylococcus aureus NRRL B313. In addition, antibiotic production can be monitored by HPLC with UV detection. 
     Following their production under submerged aerobic fermentation conditions, antibiotics M43B and M43C can be recovered from the fermentation medium by filtering the broth to remove mycelia and purifying the filtered broth by a series of adsorptions on suitable adsorbents, such as an ion-exchange resins, chemically modified hydrophobic inorganic supports used in high performance reversed-phase liquid chromatography, and high porosity polymers, eluting the M43B and M43C in each case with a suitable solvent such as aqueous acetonitrile. 
     A preferred method of preparing M43C is described by Nagarajan and Schabel in their copending application, supra. This method comprises treating M43A with trifluoroacetic acid (TFA) at a temperature of about -15° C. for about 16 hours. 
     M43B and M43C inhibit the growth of a broad spectrum of pathogenic bacteria, especially gram-positive bacteria. Table I summarizes the minimal inhibitory concentrations (MIC&#39;s) at which M43B and M43C inhibit certain organisms, as determined by standard agar-dilution assays. 
     
                       TABLE I                                                     
______________________________________                                    
In Vitro Activity of M43B and M43C                                        
                    MIC (mcg/ml)                                          
Organism              M43B    M43C                                        
______________________________________                                    
Staphylococcus aureus NRRL B313                                           
                      16      2                                           
Staphylococcus aureus V41                                                 
                      32      4                                           
Staphylococcus aureus X400                                                
                      32      4                                           
Staphylococcus aureus S13E                                                
                      32      4                                           
Staphylococcus epidermidis EPI1                                           
                      32      8                                           
Staphylococcus epidermidis 222                                            
                      32      8                                           
Streptococcus pyogenes C203                                               
                      16      2                                           
Streptococcus pneumoniae Park 1                                           
                       2      2                                           
Streptococcus faecium ATCC 9790                                           
                      32      4                                           
Streptococcus sp. group D 2041                                            
                      32      8                                           
Haemophilus influenzae C.L.                                               
                      &gt;64     &gt;64                                         
Haemophilus influenzae 76                                                 
                      &gt;64     32                                          
Escherichia coli N10  &gt;64     &gt;64                                         
Escherichia coli EC14 &gt;64     &gt;64                                         
Escherichia coli TEM  &gt;64     &gt;64                                         
Klebsiella pneumoniae X26                                                 
                      &gt;64     &gt;64                                         
Klebsiella pneumoniae X68                                                 
                      &gt;64     &gt;64                                         
Klebsiella pneumoniae KAE                                                 
                      &gt;64     &gt;64                                         
______________________________________                                    
 
    
     M43C has also shown in vivo antimicrobial activity against an experimental bacterial infection. When two doses of test compound were administered to mice in experimental infections, the activity observed was measured as an ED 50  value [effective dose in mg/kg to protect 50% of the test animals: see Warren Wick, et al., J. Bacteriol. 81, 233-235 (1961)]. The ED 50  value observed for M43C is given in Table II. 
     
                       TABLE II                                                    
______________________________________                                    
ED.sub.50 Value for M43C                                                  
            Route of    ED.sub.50 (mg/kg/2).sup.a                         
Organism    Administration                                                
                        M43C                                              
______________________________________                                    
Streptococcus                                                             
            subcutaneous                                                  
                        2.67                                              
pneumoniae                                                                
______________________________________                                    
 .sup.a LD Challenge Dose = 125                                           
 
    
     Pharmaceutical formulations of M43B, M43C, or salts of M43B or M43C (an M43 compound) are also part of this invention. The antibiotic, preferably as a pharmaceutically acceptable salt, can be formulated for oral or parenteral administration for the therapeutic or prophylactic treatment of bacterial infections. For example, an M43 compound can be admixed with conventional pharmaceutical carriers and excipients and used in the form of tablets, capsules, elixirs, suspensions, syrups, wafers and the like. The compositions comprising an M43 compound will contain from about 0.1 to about 90% by weight of the active compound, and more generally from about 10 to about 30%. The compositions may contain common carriers and excipients, such as corn starch or gelatin, lactose, sucrose, microcrystalline cellulose, kaolin, mannitol, dicalcium phosphate, sodium chloride and alginic acid. Disintegrators commonly used in the formulations of this invention include croscarmellose sodium, microcrystalline cellulose, corn starch, sodium starch glycolate and alginic acid. Tablet binders that can be included are acacia, methylcellulose, sodium carboxymethylcellulose, polyvinylpyrrolidone (Povidone), hydroxypropyl methylcellulose, sucrose, starch and ethylcellulose. Lubricants that can be used include magnesium stearate or other metallic stearates, stearic acid, silicone fluid, talc, waxes, oils and colloidal silica. Flavoring agents such as peppermint, oil of wintergreen, cherry flavoring or the like can also be used. It may be desirable to add a coloring agent to make the dosage form more esthetic in appearance or to help identify the product. 
     For intravenous (IV) use, a water soluble form of the antibiotic can be dissolved in one of the commonly used intravenous fluids and administered by infusion. Such fluids as, for example, physiological saline, Ringer&#39;s solution or 5% dextrose solution can be used. 
     For intramuscular preparations, a sterile formulation of a suitable soluble salt form of the antibiotic, for example the hydrochloride salt, can be dissolved and administered in a pharmaceutical diluent such as Water-for-Injection, physiological saline or 5% glucose solution. A suitable insoluble form of the antibiotic may be prepared and administered as a suspension in an aqueous base or a pharmaceutically acceptable oil base, e.g. an ester of a long chain fatty acid such as ethyl oleate. 
     For oral use, a sterile formulation of a suitable salt form of the antibiotic, for example, the hydrochloride salt, formulated in a diluent such as distilled or deionized water, is particularly useful. 
     Alternatively, the unit dosage form of the antibiotic can be a solution of the antibiotic or preferably a salt thereof in a suitable diluent in sterile, hermetically sealed ampoules. The concentration of the antibiotic in the unit dosage may vary, e.g. from about 1 percent to about 50 percent depending on the particular form of the antibiotic and its solubility and the dose desired by the physician. 
     In a further aspect, this invention provides a method for treating or controlling infectious diseases, especially those caused by gram-positive microorganisms, in animals. This method comprises administering to the animal an effective dose of an M43 compound. An effective dose is generally between about 1 and about 200 mg/kg of a pharmaceutically acceptable M43 compound. A preferred dose is from about 20 to about 120 mg/kg of M43 compound. A typical daily dose for an adult human is from about 500 mg to about 2.0 g. 
     In practicing this method, the antibiotic can be administered in a single daily dose or in multiple doses per day. The treatment regime may require administration over extended periods of time, e.g., for several days or for from two to three weeks. The amount per administered dose or the total amount administered will depend on such factors as the nature and severity of the infection, the age and general health of the patient, the tolerance of the patient to the antibiotic and the microorganism or microorganisms involved in the infection. 
     A convenient method of practicing the treatment method is to administer the antibiotic via IV infusion. In this procedure a sterile formulation of a suitable soluble salt of the antibiotic is incorporated in a solution of a physiological fluid, such as 5% dextrose solution, and the resulting solution is infused slowly IV. Alternatively, the piggy-back method of IV infusion can be used. 
     In another embodiment, this invention relates to methods of increasing feed-utilization efficiency in poultry, swine, sheep and cattle, of promoting growth rates in cattle raised for meat production and of enhancing milk production in lactating ruminants. For increasing feed utilization efficiency and promoting growth, an M43 compound is administered orally in a suitable feed in an amount of from about 2 to about 200 grams per ton of total feed. For beef cattle, for example, a range of about 12 to 3000 mg/head/day is suitable. For enhancing milk production in lactating ruminants, oral administration of a daily amount of from about 0.04 to about 16 mg/kg of body weight (or about 25 to about 5000 mg/ruminant/day) is suggested. 
    
    
     The following examples are provided to illustrate this invention: 
     EXAMPLE 1 
     Isolation of Antibiotics M43A, M43B and M43C from N. orientalis NRRL 2452 
     A. Separation from Vancomycin 
     Using the procedure in U.S. Pat. No. 3,067,099 (Example 2), fourteen 1200 gallon fermenters were processed to give a crude preparation in the hydrochloride salt form. This prepearation was further separated on a Dowex 50-2X resin column, selectively eluting fractions containing M43A with a 2-percent aqueous ammonium formate solution (pH 9.6) as the eluent, to give a semi-purified preparation containing M43A, M43B and M43C. 
     B. Separation of M43A, M43B and M43C 
     A portion (15 g) of material prepared as in Section A was dissolved in water (1.5 L), filtered, and applied to a CM-Sephadex C-25 (NH 4   + ) column (glass, 6-×77-cm, packed with 2 L of resin in water). The column was washed with water (2.5 L) at a rate of 5-10 ml/min to remove impurities. The column was then developed using a linear gradient of (a) 8 liters of water in the mixing chambers and (b) 8 liters of 2M NH 4  HCO 3  in the reservoir. Elution was monitored by assay against Bacillus subtilis in minimal media. Key fractions were also analyzed by analytical HPLC. The M43B- and M43C-containing fractions were combined, desalted on HP-20, concentrated and lyophilized to give 50 mg of enriched material. This material was applied to a reversed phase silica gel column (LP1-C-18) which was eluted with a CH 3  CN (13%):aqueous 0.05M KH 2  PO 4 , pH 3.2 (87%) solvent system, eluting at a flow rate of 2.5-ml/min. Fractions were monitored by analytical HPLC. The M43B-containing fractions were combined, desalted and lyophilized to give 14.6 mg of antibiotic M43B. The M43C-containing fractions were combined, desalted and lyophilized to give 6.2 mg of M43C. 
     C. Characteristics of M43B 
     M43B has an integer molecular weight of 1476 as determined by fast-atom-bombardment mass spectrometry. 
     The molecular structure of M43B, as shown in formula 1, is based on proton nuclear magnetic resonance (NMR) studies. 
     D. Characteristics of M43C 
     M43C has an integer molecular weight of 1332 as determined by fast-atom-bombardment mass spectrometry. The molecular weight of M43C is 143 units lower than that of M43A (m.w. 1475). This is consistent with the structural difference between M43A and M43C being the presence of an additional vancosomine in M43A. 
     The molecular structure of M43C, as shown in formula 2, was deduced in part from  1  H NMR studies. 
     The proton NMR assignments for M43C are summarized in Table III. The chemical shifts listed in Table III were obtained in DMSO-d 6  solution at 60° C. and at 360 MHz proton frequency. The numbering scheme used is shown in formula 13: ##STR6## 
     
                       TABLE III                                                   
______________________________________                                    
Proton NMR Assignments for M43C.sup.a                                     
Assignment     Chem. Shift                                                
______________________________________                                    
A-NH           6.45                                                       
A-2&#39;           4.15                                                       
A-1&#39;           5.21                                                       
A-2            7.86                                                       
A-5            7.24                                                       
A-6            7.46                                                       
B-NH           8.81                                                       
B-1&#39;           5.76                                                       
B-2            5.67                                                       
B-6            5.21                                                       
C-NH           10.32                                                      
C-2&#39;           4.92                                                       
C-1&#39;           5.14                                                       
C-2            7.52                                                       
C-3            7.18                                                       
C-6            7.43                                                       
D-NH           8.29                                                       
D-1&#39;           4.41                                                       
D-2            6.34                                                       
D-4            6.45                                                       
E-NH           8.40                                                       
E-1&#39;           4.45                                                       
E-2            7.16                                                       
E-5            6.68                                                       
E-6            6.75                                                       
Asn-NH         ˜6.45                                                
Asn-α    4.37                                                       
Asn-β&#39;s   2.48 and                                                   
 &#34;             2.12                                                       
               7.29 and                                                   
 &#34;             6.72                                                       
Leu-.sup.+N(CH.sub.3).sub.3                                               
               3.20                                                       
Leu-α    4.72                                                       
Leu-β&#39;s   1.91 and                                                   
               1.59                                                       
Leu-γ    1.46                                                       
Leu-δ&#39;s  0.93 and                                                   
               0.87                                                       
Glucose #1     5.32                                                       
#2             3.40                                                       
#5             3.24                                                       
#6             3.53 and                                                   
               3.70                                                       
______________________________________                                    
 .sup.a Phenols not yet assigned                                          
 
    
     EXAMPLE 2 
     Shake-flask Fermentation of N. orientalis M43-05865 to Produce M43B and M43C 
     A lyophilized pellet of Nocardia orientalis M43-05865 (NRRL 2450) is dispersed in 1-2 ml of sterilized water. This solution (&lt;0.1 ml) is used to inoculate an agar slant having the following composition: 
     
         ______________________________________                                    
Ingredient            Amount (g/L.)                                       
______________________________________                                    
Dextrin               10                                                  
Enzymatic hydrolysate of casein.sup.a                                     
                      2                                                   
Beef extract          1                                                   
Yeast extract         1                                                   
Agar                  20                                                  
Distilled water q.s. to                                                   
                      1      liter                                        
______________________________________                                    
 .sup.a NZ Amine A, Humko Sheffield Chemical, Lyndhurst NJ                
 
    
     The inoculated slant is incubated at 30° C. for 4-6 days. The mature slant culture is covered with sterile distilled water and scraped with a loop to loosen the spores. The resulting spore suspension (1 ml) is used to inoculate 100 ml of a vegetative medium having the following composition: 
     
         ______________________________________                                    
Ingredient          Amount (g/L.)                                         
______________________________________                                    
Glucose             15                                                    
Soybean meal        15                                                    
Cornsteep solids    5                                                     
CaCO.sub.3          2                                                     
NaCl                5                                                     
Tap H.sub.2 O q.s. to                                                     
                    1      liter                                          
______________________________________                                    
 
    
     The inoculated vegetative medium is incubated in a 500-ml Erlenmeyer flask for 24-48 hours at 30° C. on a reciprocal shaker with a 2-inch stroke at 108 RPM or on a rotary shaker operating at 250 RPM. 
     This incubated vegetative medium (5 ml) is used to inoculate 100 ml of a sterilized (120° C. for 30 minutes) production medium having the following composition: 
     
         ______________________________________                                    
Ingredient          Amount (g/L.)                                         
______________________________________                                    
Glucose             10                                                    
Edible molasses     20                                                    
Peptone.sup.a       5                                                     
CaCO.sub.3          2                                                     
Tap H.sub.2 O q.s. to                                                     
                    1      liter                                          
______________________________________                                    
 .sup.a Bacto (Difco Laboratories, Detroit, MI)                           
 
    
     The inoculated fermentation medium is incubated in a 500-ml Erlenmeyer flask at 25°-30° C. for 72-96 hours on either a rotary shaker operating at 250 RPM or a reciprocal shaker operating at 108 strokes per minute. The pH of the uninoculated medium varies with the medium used for production, but the production media of Examples 2-5 have an initial pH range of 6.0 to 7.5 and a harvest pH range of 6.5 to 8.0. 
     B. Isolation of M43 Complex 
     Whole broth (2 L.), prepared as described in Section A, was filtered. The filtrate was treated with a cation exchange resin (Dowex 50W-X4, H + , NH 4   + , pH 5.0), using 100-ml of resin and stirring batchwise for 30 minutes. The effluent was decanted and discarded. The resin was washed thoroughly with water, and the water wash was discarded. The resin was then eluted batchwise with 1N NH 4  OH (250 ml and 175 ml per batch). The eluates were combined and concentrated under vacuum to a volume of about 50 ml. An aliquot (2 ml) was removed for assay, and the remaining concentrate was lyophilized to give 300 mg of M43 complex. 
     C. Separation of M43B and M43C by Analytical HPLC 
     A portion of the M43 complex prepared as described in Section B is examined by analytical HPLC, using the following system: 
     Column: Beckman Ultrasphere (5μ particle size), ODS, 25 cm. 
     Mobile Phase: Solvent A: CH 3  CN/TEAP (5:95), Solvent B: CH 3  CN/TEAP (2:3). 
     [TEAP=0.5% aqueous triethylamine adjusted to pH 3 with conc. phosphoric acid]. 
     Gradient: 9% B to 70% B over a 40-min period, then hold for 5 min. at 70% B. 
     Flow Rate: 1.0 ml/min. 
     Detection: UV at 254 nm. 
     
         ______________________________________                                    
M43A Factor       Retention Time (min.)                                   
______________________________________                                    
A51568 factor B.sup.a                                                     
                   5.92                                                   
A51568 factor A    8.96                                                   
vancomycin        12.23                                                   
desvancosamine-A51568A                                                    
                  17.59                                                   
M43D              19.96                                                   
desvancosamine-vancomycin.sup.a                                           
                  20.38                                                   
M43A              24.26                                                   
M43B.sup.a        25.46                                                   
M43C.sup.a        29.58                                                   
agluco A51568A    36.97                                                   
agluco-vancomycin 37.72                                                   
agluco-M43A       39.79                                                   
______________________________________                                    
 .sup.a Trace amounts                                                     
 
    
     EXAMPLE 3 
     Antibiotics M43B and M43C prepared according to the method of Example 2, but using the following production medium: 
     
         ______________________________________                                    
Ingredient          Amount (g.L.)                                         
______________________________________                                    
Glucose             10                                                    
Yeast               5                                                     
Distillers solubles 5                                                     
KCl                 4                                                     
CaCO.sub.3          1                                                     
Tap H.sub.2 O q.s. to                                                     
                    1      liter                                          
______________________________________                                    
 
    
     EXAMPLE 4 
     M43B and M43C prepared by the method of Example 2, but using the following production medium: 
     
         ______________________________________                                    
Ingredient             Amount                                             
______________________________________                                    
Casamino acids         5     g/L                                          
Dextrin                5     g/L                                          
Glycerol               5     g/L                                          
Blackstrap molasses    10    g/L                                          
Yeast                  5     g/L                                          
K.sub.2 HPO.sub.4      1     g/L                                          
Mineral Stock          5     ml                                           
Tap H.sub.2 O q.s. to  1     liter                                        
______________________________________                                    
 
    
     EXAMPLE 5 
     M43B and M43C prepared by the method of Example 2, but using the following production medium: 
     
         ______________________________________                                    
Ingredient          Amount (g/L.)                                         
______________________________________                                    
Soybean meal        15                                                    
Casein              1                                                     
NaNO.sub.3          3                                                     
Glucose syrup       20                                                    
Tap H.sub.2 O q.s. to                                                     
                    1      liter                                          
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     EXAMPLE 6 
     Preparation of M43C 
     M43A (398 mg) was dissolved in TFA (10 ml). The resulting solution was kept at -15° C. for 30 hours, and then was evaporated to dryness and freeze-dried. The reaction product was purified by reversed-phase HPLC using the system described in Example 2, Section C, to give 40 mg of M43C as identified by NMR and FABMS. 
     EXAMPLE 7 
     M43C Tablet Formulation 
     Preparation of tablets containing 250 mg of M43C: 
     
         ______________________________________                                    
Ingredient              Weight                                            
______________________________________                                    
M43C diphosphate        282.9  mg                                         
Microcrystalline cellulose                                                
                        101.1  mg                                         
Croscarmellose sodium   12.0   mg                                         
Providone               12.0   mg                                         
Magnesium stearate      3.0    mg                                         
Stearic acid            4.0    mg                                         
Purified water          0.16   ml                                         
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     Add M43C diphosphate, a portion of the microcrystalline cellulose and a portion of the croscarmellose sodium to a suitable container and blend until homogenous. Prepare a solution of Povidone in water, and add the Povidone solution to the blended powders. Granulate the resulting mixture, size if necessary and dry. Add the remaining microcrystalline cellulose and croscarmellose sodium to the dried mixture and blend. Add magnesium stearate and stearic acid, and blend the mixture. Compress the resulting powder blend into tablets with a theoretical weight of 415 mg. Each tablet contains M43C diphosphate equivalent to 250 mg of M43C. 
     EXAMPLE 8 
     M43C Capsule Formulation 
     
         ______________________________________                                    
Ingredient             Weight                                             
______________________________________                                    
M43C dihydrochloride   262.2   mg                                         
Corn starch flowable powder                                               
                       137.65  mg                                         
Silicone fluid 350 centistokes                                            
                       2.75    mg                                         
Corn starch            147.1   mg                                         
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     Blend M43C dihydrochloride, starch flowable powder, silicone fluid 350 centistokes and starch powder in a suitable mixer until homogeneous. Fill into appropriate size hard gelatin capsules to a net fill weight of 550 mg. Each capsule contains M43C dihydrochloride equivalent to 250 mg of M43C. 
     EXAMPLE 9 
     M43C Suspension Formulation 
     Prepare M43C in a sterile insoluble form by crystallization or precipitation. Mill or screen to correct particle size for suspension. Suspend the antibiotic in the following vehicle: 
     
         ______________________________________                                    
Ingredient     Amount                                                     
______________________________________                                    
Lecithin       1%                                                         
Sodium citrate 2%                                                         
Propylparaben  0.015%                                                     
Water for Injection                                                       
               q.s. to desired volume.                                    
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     Sterilize the suspension. The suspension may be manufactured in the bulk and filled into vials or may be prepared by adding the vehicle to the M43C in the vial.