Summary of laboratory studies on the antibacterial activity of cefaclor

Zusammenfassung der In-vitro-Studien zur antibakteriellen Wirksamkeit von Cefaclor


Laboratory aspects of cefaclor, a new orally-effective cephalosporin antibiotic, are summarized. On the basis of data from a variety of studies, the useful antibacterial spectrum of cefaclor is shown to include all classes of bacteria that are generally susceptible to cephalothin and cephalexin. Cefaclor has a significant potency advantage over cephalexin against manyEnterobacteriaceae, Haemophilus sp. andStreptococcus pneumoniae. Bacteria that are susceptible to cefaclor are killed by concentrations at or near the inhibitory concentration. In vitro enzymatic hydrolysis experiments have shown that cefaclor is a relatively good substrate for several β-lactamases. Orally administered cefaclor is effective in protection of mice from the lethal effects of intraperitoneal challenges with cefaclor-susceptible bacteria. The chemical instability of cefaclor, test medium composition and inoculum density influence the results of in vitro susceptibility tests with cefaclor. Methods for routine susceptibility testing are described.


Die In-vitro-Aspekte von Cefaclor, einem neuen oralen Cephalosporin, werden zusammengefaßt. Auf der Basis der Ergebnisse einer Vielzahl von Studien kann gezeigt werden, daß das antibakterielle Spektrum von Cefaclor alle Erreger umfaßt, die üblicherweise gegenüber Cephalotin und Cephalexin empfindlich sind. Cefaclor hat bei vielenEnterobacteriaceae, Haemophilus sp. undStreptococcus pneumoniae eine signifikante Wirksamkeitsüberlegenheit gegenüber Cephalexin. Bakterien, die Cefaclor-empfindlich sind, werden bei oder nahe der Hemmkonzentration auch abgetötet. Invitro-Studien zur enzymatischen Hydrolyse haben gezeigt, daß Cefaclor für einige β-Laktamasen ein relativ gutes Substrat darstellt. Oral verabreichtes Cefaclor bewahrt Mäuse vor dem letalen Ausgang nach intraperitonealer Zufuhr Cefaclor-empfindlicher Keime. Die chemische Instabilität von Cefaclor, die Zusammensetzung des Testmediums, sowie die Inokulumdichte beeinflussen die Ergebnisse der In-vitro-Studien mit Cefaclor. Die Methoden zur routinemäßigen Empfindlichkeitsprüfung werden beschrieben.

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  1. 1.

    U. S. Food and Drug Administration Rules and Regulations. Federal Register 37 (1972) 20525–20529.

    Google Scholar 

  2. 2.

    Reed, L. J., Muench, H. A simple method of estimating fifty percent endpoints. Am. J. Hyg. 27 (1938) 493.

    Google Scholar 

  3. 3.

    Bill, N. J., Washington, J. A. Comparison of in vitro activity of cephalexin, cephradine, and cefaclor. Antimicrob. Agents Chemother. 11 (1977) 470–474.

    Google Scholar 

  4. 4.

    Shadomy, S., Mayhall, C. G., Apollo, E. In vitro activity of five oral cephalosporins against anaerobic pathogenic bacteria. J. Infect. Dis. 136 (1977) 697–700.

    Google Scholar 

  5. 5.

    Kammer, R. B., Preston, D. A., Turner, J. R., Hawley, L. C. Rapid detection of ampicillin-resistantHaemophilus influenzae and their susceptibility to sixteen antibiotics. Antimicrob. Agents Chemother. 8 (1975) 91–94.

    Google Scholar 

  6. 6.

    Sanders, C. C. In vitro studies with cefaclor, a new oral cephalosporin. Antimicrob. Agents Chemother. 12 (1977) 490–497.

    Google Scholar 

  7. 7.

    Silver, M. S., Counts, G. W., Zeleznik, D., Turck, M. Comparison of in vitro antibacterial activity of three oral cephalosporins: cefaclor, cephalexin, and cephradine. Antimicrob. Agents Chemother. 12 (1977) 591–596.

    Google Scholar 

  8. 8.

    Fekety, R., Fekety, S.: Comparative in vitro activity of cefaclor. In:Siegenthaler, W., Lüthy, R. (ed.): Current chemotherapy, Proc. 10th Intern. Congr. Chemother. American Society for Microbiology, Washington, 1978, p. 880–881.

  9. 9.

    Santoro, J., Levison, M. E. In vitro activity of cefaclor, a new orally administered cephalosporin antibiotic. Antimicrob. Agents Chemother. 12 (1977) 442–443.

    Google Scholar 

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Der gleiche Vortrag wurde auf dem Symposium „Clinical Advances in Oral Antibiotic Therapy“, London, 21.–22. 9. 1978, gehalten und in „Postgraduate Medical Journal“ 55 Suppl. 4 (1979) 22–29, publiziert. Nachdruck mit freundlicher Genehmigung von The Fellowship of Postgraduate Medicine.

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Preston, D.A. Summary of laboratory studies on the antibacterial activity of cefaclor. Infection 7, S557–S561 (1979).

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  • Cephalosporin
  • Cephalexin
  • Cefaclor
  • Cephalothin
  • Significant Potency