Summary
In these experiments, fibrin clots infected withStreptococcus faecalis were inserted under the skin of rabbits. Groups of five animals either received two i. v. bolus injections of 37,500 units/kg of penicillin G at 0 and 3 hours, one i. v. bolus injection of 6 mg/kg of gentamicin at 0 hour or the combination of both antibiotics. Other groups of rabbits were given a constant infusion of 75,000 units/kg of penicillin G, 6 mg/kg or 9 mg/kg of gentamicin or the combination of both drugs administered over six hours. The respective minimal inhibitory concentrations (MIC) of penicillin G and gentamicin against theS. faecalis were 4 units/ml and 3.1 µg/ml. The minimal bactericidal concentrations (MBC) were 32 units and 6.2 µg/ml. The analysis of the bactericidal activity of the serum against the enterococcus showed that bolus injections of the combination penicillin G — gentamicin were two to eight times more effective than constant infusions. The bactericidal activity of both antibiotics in the clots was determined by bacterial counts of living bacteria after dissolution of the clots with trypsin. Here again, in vivo synergism could be demonstrated after bolus injections of both drugs while constant infusion of the combination was ineffective. To achieve reasonable levels of both antibiotics which could allow “synergism” at the infected sites the dose of gentamicin had to be increased to 9 mg/kg given over 6 hours. This lead to potentially toxic levels of 12 µg/ml of gentamicin in serum. These studies suggest that in vivo synergism againstS. faecalis can be achieved with minimal amount of antimicrobials as long as they are given in a bolus fashion.
Zusammenfassung
MitStreptococcus faecalis infizierte Fibringerinnsel wurden Kaninchen unter die Haut eingebracht. Gruppen von je fünf Tieren bekamen sodann entweder zwei intravenöse Injektionen zu 37 500 E/kg Penicillin G zum Zeitpunkt 0 und nach 3 h oder eine Injektion von 6 mg/kg Gentamycin zum Zeitpunkt 0 h oder die Kombination beider Antibiotika. Andere Gruppen erhielten eine Dauerinfusion von 75 000 E/kg Penicillin G, 6 oder 9 mg/kg Gentamycin oder die Kombination beider Präparate für sechs Stunden. Die minimalen Hemmkonzentrationen von Penicillin G und Gentamycin gegenS. faecalis betrugen je 4 E/ml und 3.1 µg/ml, die minimalen bakteriziden Konzentrationen 32 E und 6.2 µg/ml. Die Analyse der bakteriziden Serumaktivität gegen den Enterokokkus zeigte, daß Einzelinjektionen der Kombination Penicillin G-Gentamycin 2–8mal wirksamer waren als Dauerinfusionen. Der bakterizide Effekt beider Antibiotika in den Gerinnseln wurde durch Zählung der lebenden Bakterien nach Verflüssigung der Gerinnsel mit Trypsin bestimmt. Auch hier ließ sich ein In-vivo-Synergismus nach Stoßinjektion der beiden Präparate nachweisen, hingegen war die Dauerinfusion der Präparatekombination wirkungslos. Eine ausreichende Konzentration beider Antibiotika, durch die ein „Synergismus“ am Infektionsort zu erzielen war, war nur durch eine Steigerung der Gentamycindosis auf 9 mg/kg für sechs Stunden zu erreichen. Dies führte zu potentiell toxischen Serumkonzentrationen von 12 µg/ml Gentamycin. Diese Ergebnisse erlauben die Folgerung, daß ein In-vivo-Synergismus gegenS. faecalis mit minimalen Antibiotikamengen zu bewirken ist, sofern sie „geballt“ verabfolgt werden.
Similar content being viewed by others
Literature
Eagle, H., Fleischmann, R., Levy, M. “Continuous” vs “Discontinuous” therapy with penicillin: The effect of the interval between injections on therapeutic efficacy. N. Engl. J. Med. 248 (1953) 481–488.
Dorney, E. R. Endocarditis. In: The heart. (Ed.W. Hurst, R. B. Logue), p. 1175. McGraw-Hill, New York 1970.
Bigger, J. W. Treatment of staphylococcal infections with penicillin by intermittent sterilization, Lancet 2 (1944) 497–500.
Eagle, H. Experimental approach to the problem of treatment failure with penicillin: I. Group A streptococcal infection in mice. Am. J. Med. 13 (1952) 389–399.
Barza, M., Brusch, J., Bergeron, M. G., Weinstein, L. Penetration of antibiotics into fibrin loci in Vivo: III. Intermittent vs continuous infusion and the effect of probenicid. J. Infect. Dis. 129 (1974) 73–78.
Plorde, J. J., Garcia, M., Petersdorf, R. G. Studies on the pathogenesis of meningitis: IV. Penicillin levels in the cerebrospinal fluid in experimental meningitis. J. Lab. Clin. Med. 64 (1964) 960–969.
Bergeron, M. G.: A review of models for the therapy of experimental infections. Scand. J. Infect. Dis. In press.
Daikos, G. K., Weinstein, L. Mikrobielle persistenz studiert in vivo. Durch Anwendung Kunstlichel fibringerinnsel: I. Wachstum von Bakterien in den fibringerinnseln. Streptococcus viridans — Persistenz nach Penicillin-Verabreichung 38 (1960) 521–528.
Bergeron, M. G., Brusch, J., Barza, M., Weinstein, L. Bactericidal activity and pharmacology of cefazolin. Antimicrob. Ag. Chemother. 4 (1973) 396–401.
Kavanagh, F., Dennin, L. J. Penicillin. In: Analytical microbiology (ED.:F. Kavanagh), p. 327. Academic Press, New York 1963.
Sabath, L. D. Rapid assay of some nephrotoxic antibiotics and the assay of antibiotics in mixtures. In: Analytical microbiology (Ed.F. Kavanagh) p. 235. Academic Press, New York 1972.
Gordon, R. C., Regamey, C., Kirby, W. M. M. Comparative clinical pharmacology of amoxicillin and ampicillin administered orally. Antimicrob. Ag. Chemother. 1 (1972) 504–507.
Bergeron, M. G., Nguyen, B. M., Trottier, S., Gauvreau, L. Penetrance of cefamandole, cephalothin and desacetylcephalothin in fibrin clots. Antimicrob. Ag. Chemother. 12 (1977) 682–687.
Watanakunakorn, C. Penicillin combined with gentamicin and streptomicin: Synergism against enterococci. J. Infect. Dis. 124 (1971) 581–586.
Weinstein, A. J., Moellering, R. C. Penicillin and gentamicin therapy for enterococcal infections. J. Am. Med. Assoc. 223 (1973) 1030–1032.
Hook, E. W., Roberts, R. B., Sande, M. A. Antimicrobial therapy of experimental endocarditis. Antimicrob. Ag. Chemother. 8 (1975) 564–570.
Barry, A. L., Sabath, L. D.: Special tests: Bactericidal activity and activity of antimicrobics in combination. In: Manual of clinical microbiology (Ed.:E. H. Lennette, E. H. Spaulding, J. P. Truant), p. 431. American Society for microbiology, Washington, D. C.
Bryan, C. S., Marney, S. R., Alford, R. H., Bryant, R. E. Gram-negative bacillary endocarditis: Interpretation of the serum bactericidal test. Am. J. Med. 58 (1975) 209–215.
Klastersky, J., Daneau, D., Swings, G., Weerts, D. Antibacterial activity in serum and urine as a therapeutic guide in bacterial infections. J. Infect. Dis. 129 (1974) 187–193.
Mandell, G. L. The laboratory in diagnosis and management. In: Infective endocarditis (Ed.D. Kaye), p. 155. University Park Press, Baltimore 1976.
Carrizosa, J., Kaye, D. Antibiotic concentrations in serum, serum bactericidal activity and results of therapy of streptococcal endocarditis in rabbits. Antimicrob. Ag. Chemother. 12 (1977) 479–483.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Bergeron, M.G., Nguyen, B.M. & Gauvreau, L. Influence of constant infusion versus bolus injections of antibiotics on in vivo synergy. Infection 6 (Suppl 1), S38–S46 (1978). https://doi.org/10.1007/BF01646064
Issue Date:
DOI: https://doi.org/10.1007/BF01646064