Abstract
Antimicrobial susceptibility testing of pneumococci is now essential to monitor for the presence of resistance to agents such as the penicillins, macrolides, lincomycins, chloramphenicol, and tetracycline. In this study, clinical isolates of a selection of resistant South African strains were tested for antimicrobial susceptibility by minimal inhibitory concentration (MIC) determination and by a modified Kirby-Bauer disk diffusion technique, using Mueller-Hinton medium supplemented with 5% horse blood. Disk diffusion breakpoints were determined for penicillin G, erythromycin, clindamycin, tetracycline, chloramphenicol, and rifampin. Reliable results were obtained on disk diffusion for all these agents except for penicillin G. With 6-μg penicillin G disks, zones of strains with intermediate penicillin susceptibility overlapped those of sensitive and resistant strains. With 5-μg methicillin disks, clearer separation of strains based on susceptibility to penicillin G occurred. Strains with zones of <35 mm around penicillin G disks and <25 mm around methicillin disks should have penicillin G MICs determined to confirm their resistance to penicillin G. In view of the potential for pneumococci to be resistant to the agents used in this study, antimicrobial susceptibility of all clinically significant isolates should be determined.
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Selected References
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- Appelbaum P. C., Bhamjee A., Scragg J. N., Hallett A. F., Bowen A. J., Cooper R. C. Streptococcus pneumoniae resistant to penicillin and chloramphenicol. Lancet. 1977 Nov 12;2(8046):995–997. doi: 10.1016/s0140-6736(77)92892-6. [DOI] [PubMed] [Google Scholar]
- Bennett J. V., Camp H. M., Eickhoff T. C. Rapid sulfonamide disc sensitivity test for meningococci. Appl Microbiol. 1968 Jul;16(7):1056–1060. doi: 10.1128/am.16.7.1056-1060.1968. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Binda G., Domenichini E., Gottardi A., Orlandi B., Ortelli E., Pacini B., Fowst G. Rifampicin, a general review. Arzneimittelforschung. 1971 Dec;21(12):1907–1977. [PubMed] [Google Scholar]
- Cates K. L., Gerrard J. M., Giebink G. S., Lund M. E., Bleeker E. Z., Lau S., O'Leary M. C., Krivit W., Quie P. G. A penicillin-resistant pneumococcus. J Pediatr. 1978 Oct;93(4):624–626. doi: 10.1016/s0022-3476(78)80901-9. [DOI] [PubMed] [Google Scholar]
- Cooksey R. C., Facklam R. R., Thornsberry C. Antimicrobial susceptibility patterns of Streptococcus pneumoniae. Antimicrob Agents Chemother. 1978 Apr;13(4):645–648. doi: 10.1128/aac.13.4.645. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Dixon J. M., Lipinski A. E., Graham M. E. Detection and prevalence of pneumococci with increased resistance to penicillin. Can Med Assoc J. 1977 Nov 19;117(10):1159–1161. [PMC free article] [PubMed] [Google Scholar]
- Jacobs M. R., Koornhof H. J., Robins-Browne R. M., Stevenson C. M., Vermaak Z. A., Freiman I., Miller G. B., Witcomb M. A., Isaäcson M., Ward J. I. Emergence of multiply resistant pneumococci. N Engl J Med. 1978 Oct 5;299(14):735–740. doi: 10.1056/NEJM197810052991402. [DOI] [PubMed] [Google Scholar]
- Robins-Brown R. M., Gaspar M. N., Ward J. I., Wachsmuth I. K., Koornhof H. J., Jacobs M. R., Thornsberry C. Resistance mechanisms of multiply resistant pneumococci: antibiotic degradation studies. Antimicrob Agents Chemother. 1979 Mar;15(3):470–474. doi: 10.1128/aac.15.3.470. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Tarpay M. Importance of antimicrobial susceptibility testing of Streptococcus pneumoniae. Antimicrob Agents Chemother. 1978 Oct;14(4):628–629. doi: 10.1128/aac.14.4.628. [DOI] [PMC free article] [PubMed] [Google Scholar]