Abstract
The relationship between the growth rate and the kill rate was used to evaluate and to compare the in vitro bactericidal activities of cefdinir, a new oral cephalosporin, and cefaclor against Streptococcus pneumoniae and beta-lactamase-producing strains of Haemophilus influenzae. These frequently encountered pathogens of community-acquired respiratory tract infections are usually susceptible to both drugs. The MIC ranges for cefdinir and cefaclor were, respectively, 0.03 to 0.06 and 0.25 to 0.5 micrograms/ml for S. pneumoniae and 0.25 and 4 to 8 micrograms/ml for H. influenzae. The colony counts (CFU per milliliter) measured after 6 h of exposure to a range of antibiotic concentrations in broth were plotted against the colony count of the control culture over the same period of time. Higher kill rates versus bacterial growth rates were noted for S. pneumoniae for both drugs (positive balance). Conversely, lower kill rates versus growth rates were noted for H. influenzae for both drugs (negative balance). In conclusion, the bactericidal activities of both drugs against S. pneumoniae and H. influenzae were similar when expressed by the relationship between the growth rate and the kill rate at 6 h, but cefdinir was more active at lower concentrations.
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Selected References
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- Bergeron M. G., Lavoie G. Y. Tolerance of Haemophilus influenzae to beta-lactam antibiotics. Antimicrob Agents Chemother. 1985 Aug;28(2):320–325. doi: 10.1128/aac.28.2.320. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bottone E. J., Brandman Z., Schneierson S. S. Spheroplasts of Haemophilus influenzae induced by cell wall-active antibiotics and their effect upon the interpretation of susceptibility tests. Antimicrob Agents Chemother. 1976 Feb;9(2):327–333. doi: 10.1128/aac.9.2.327. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Goessens W. H., Fontijne P., Michel M. F. Factors influencing detection of tolerance in Staphylococcus aureus. Antimicrob Agents Chemother. 1982 Sep;22(3):364–368. doi: 10.1128/aac.22.3.364. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Handwerger S., Tomasz A. Antibiotic tolerance among clinical isolates of bacteria. Rev Infect Dis. 1985 May-Jun;7(3):368–386. doi: 10.1093/clinids/7.3.368. [DOI] [PubMed] [Google Scholar]
- Hedges A. J., Shannon R., Hobbs R. P. Comparison of the precision obtained in counting viable bacteria by the spiral plate maker, the droplette and the Miles & Misra methods. J Appl Bacteriol. 1978 Aug;45(1):57–65. doi: 10.1111/j.1365-2672.1978.tb04198.x. [DOI] [PubMed] [Google Scholar]
- Holzhoffer S., Süssmuth R., Haag R. Oscillating tolerance in synchronized cultures of Staphylococcus aureus. Antimicrob Agents Chemother. 1985 Sep;28(3):456–457. doi: 10.1128/aac.28.3.456. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ishida K., Guze P. A., Kalmanson G. M., Albrandt K., Guze L. B. Variables in demonstrating methicillin tolerance in Staphylococcus aureus strains. Antimicrob Agents Chemother. 1982 Apr;21(4):688–690. doi: 10.1128/aac.21.4.688. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Jorgensen J. H., Doern G. V., Maher L. A., Howell A. W., Redding J. S. Antimicrobial resistance among respiratory isolates of Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae in the United States. Antimicrob Agents Chemother. 1990 Nov;34(11):2075–2080. doi: 10.1128/aac.34.11.2075. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kim K. S., Anthony B. F. Importance of bacterial growth phase in determining minimal bactericidal concentrations of penicillin and methicillin. Antimicrob Agents Chemother. 1981 Jun;19(6):1075–1077. doi: 10.1128/aac.19.6.1075. [DOI] [PMC free article] [PubMed] [Google Scholar]
- May J. R., Roberts D. E., Ingold A., Want S. V. Osmotically stable L forms of Haemophilus influenzae and their significance in testing sensitivity to penicillins. J Clin Pathol. 1974 Jul;27(7):560–564. doi: 10.1136/jcp.27.7.560. [DOI] [PMC free article] [PubMed] [Google Scholar]
- McDERMOTT W. Microbial persistence. Yale J Biol Med. 1958 Feb;30(4):257–291. [PMC free article] [PubMed] [Google Scholar]
- Neu H. C., Fu K. P. Cefaclor: in vitro spectrum of activity and beta-lactamase stability. Antimicrob Agents Chemother. 1978 Apr;13(4):584–588. doi: 10.1128/aac.13.4.584. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Neu H. C., Saha G., Chin N. X. Comparative in vitro activity and beta-lactamase stability of FK482, a new oral cephalosporin. Antimicrob Agents Chemother. 1989 Oct;33(10):1795–1800. doi: 10.1128/aac.33.10.1795. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Sabath L. D., Wheeler N., Laverdiere M., Blazevic D., Wilkinson B. J. A new type of penicillin resistance of Staphylococcus aureus. Lancet. 1977 Feb 26;1(8009):443–447. doi: 10.1016/s0140-6736(77)91941-9. [DOI] [PubMed] [Google Scholar]
- Sherris J. C. Problems in in vitro determination of antibiotic tolerance in clinical isolates. Antimicrob Agents Chemother. 1986 Nov;30(5):633–637. doi: 10.1128/aac.30.5.633. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Taylor P. C., Schoenknecht F. D., Sherris J. C., Linner E. C. Determination of minimum bactericidal concentrations of oxacillin for Staphylococcus aureus: influence and significance of technical factors. Antimicrob Agents Chemother. 1983 Jan;23(1):142–150. doi: 10.1128/aac.23.1.142. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Tuomanen E., Cozens R., Tosch W., Zak O., Tomasz A. The rate of killing of Escherichia coli by beta-lactam antibiotics is strictly proportional to the rate of bacterial growth. J Gen Microbiol. 1986 May;132(5):1297–1304. doi: 10.1099/00221287-132-5-1297. [DOI] [PubMed] [Google Scholar]
- Woolfrey B. F., Enright M. A. Ampicillin killing curve patterns for ampicillin-susceptible nontypeable Haemophilus influenzae strains by the agar dilution plate count method. Antimicrob Agents Chemother. 1990 Jun;34(6):1079–1087. doi: 10.1128/aac.34.6.1079. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Yourassowsky E., Van Der Linden M. P., Lismont M. J. Growth curves, microscopic morphology, and subcultures of beta-lactamase-positive and -negative Haemophilus influenzae under the influence of ampicillin and cefamandole. Antimicrob Agents Chemother. 1979 Mar;15(3):325–331. doi: 10.1128/aac.15.3.325. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Yourassowsky E., Van der Linden M. P., Crokaert F., Glupczynski Y. Effect of antibiotics carry-over on bacterial counting by 'spiral plating'. J Antimicrob Chemother. 1988 Jan;21(1):138–140. doi: 10.1093/jac/21.1.138. [DOI] [PubMed] [Google Scholar]