Penicillin

About: Penicillin is a research topic. Over the lifetime, 17916 publications have been published within this topic receiving 368480 citations. The topic is also known as: penicillin antibiotic & PCN.

Effect of Growth Rate on the Synthesis of Penicillin by Penicillium chrysogenum in Batch and Chemostat Cultures.

Abstract: The kinetics of penicillin production by Penicillium chrysogenum Wis 54-1255 in a glucose-limited chemostat and in batch cultures are reported. The specific production rate of penicillin, q(pen) (units per milligram of dry weight per hour) was independent of specific growth rate over the range 0.014 to 0.086 hr. Growth was stopped by restricting the glucose supply to the "maintenance ration," that is, the glucose requirement of the organism at zero growth rate with all other nutrients in excess. Under such conditions, the organism dry weight remained constant, but the q(pen) fell approximately linearly to zero at a rate inversely related to the previous growth rate. Glucose supplied in excess of the maintenance ration inhibited the decay of q(pen). At a critical growth rate between 0.009 and 0.014 hr, the decay was completely inhibited. Quantitative expressions for the q(pen) of growing and nongrowing cultures were derived and used to predict the steady-state concentrations of penicillin accumulating in one- and two-stage continuous processes. A rational explanation of the kinetics of penicillin accumulation in batch cultures is given, relating the rate of penicillin synthesis to growth rate. It is concluded that an important role of corn steep liquor (CSL), a heterogeneous carbon and nitrogen source commonly used in penicillin production media, is the provision of substrates which allow a high concentration of mold to be reached before the growth rate falls below the critical value. CSL had no significant effect on q(pen).

In vitro and in vivo susceptibility of the Lyme disease spirochete, Borrelia burgdorferi, to four antimicrobial agents

Abstract: The antimicrobial susceptibility of Borrelia burgdorferi isolated from human spinal fluid was determined in vitro and in vivo. A broth dilution technique was used to determine the MBCs of four antimicrobial agents. The Lyme disease spirochete was most susceptible to ceftriaxone (MBC, 0.04 microgram/ml) and erythromycin (MBC, 0.05 microgram/ml), then tetracycline (MBC, 0.8 microgram/ml), and finally penicillin G (MBC, 6.4 micrograms/ml). Syrian hamsters were used to determine the 50% curative doses (CD50s) of the four antimicrobial agents. Ceftriaxone and tetracycline had the highest activities, with CD50s of 24.0 and 28.7 mg/kg [corrected], respectively. Both erythromycin and penicillin G possessed low activities. The CD50 of erythromycin was 235.3 mg/kg [corrected], and the CD50 of penicillin G was greater than 197.5 mg/kg [corrected].

Prophylaxis against group a streptococcal infections in rheumatic fever patients

Abstract: There are two effective methods now available for the prevention of rheumatic fever or its recurrences. Prompt and vigorous treatment of the initiating streptococcal infection with one of the antibiotic drugs may prevent the complication of rheumatic fever, or the maintenance of continuous antibiotic therapy in the rheumatic subject may prevent recurrences by affording protection against infection by group A streptococci.1 Penicillin promises to be the antibiotic of choice for the prevention of rheumatic fever by either of the above methods for several reasons: its action is bactericidal rather than bacteriostatic 2; the streptococcal pharyngeal carrier state is eliminated most effectively by treatment with adequate doses of penicillin 3; strains of group A streptococci resistant to penicillin have not emerged, despite the widespread use of this drug 4; and fatal or serious toxic reactions are relatively rare. The problem of employing penicillin as a prophylactic agent is largely a practical one. Current methods for maintaining continuous prophylaxis with penicillin in¬ volve oral administration of relatively large doses, once to three times daily, with the patient in the fasting state.le The success of such treatment depends largely on the pa¬ tient's strict adherence to this regimen without interrup¬ tion. In addition, only a fraction (about one-fifth) of the dose of penicillin administered is absorbed and the oral route is, consequently, costly and wasteful. Parenteral administration of available repository procaine penicillin preparations has not been employed for continuous pro¬ phylaxis because of the frequency with which injections would be required. If, however, penicillin could be main¬ tained in the tissues for protracted periods by means of single injections given at infrequent intervals, parenteral administration should prove economical and practical. Treatment of the initiating streptococcal pharyngitis with penicillin to prevent the subsequent development of rheumatic fever usually requires repeated intramuscular injections or large orally administered doses of penicillin for about 10 days." In routine medical practice, bacterio¬ logical confirmation of the streptococcal etiology of pharyngitis is rarely obtained, and penicillin often is not administered for an adequate period. There would, there¬ fore, be considerable practical advantage in a prepara¬ tion with which successful treatment of streptococcal respiratory infection could be obtained by a single intra¬ muscular injection. Recently, a new repository penicillin compound was synthesized that provides detectable levels of penicillin in the blood of humans for prolonged periods following single intramuscular injections.7 N,N' dibenzylethylenediamine dipenicillin G ("bicillin") is a sparingly soluble