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Journal of Clinical Microbiology logoLink to Journal of Clinical Microbiology
. 1993 May;31(5):1246–1250. doi: 10.1128/jcm.31.5.1246-1250.1993

Testing of Streptococcus pneumoniae for resistance to penicillin.

K J Marshall 1, D M Musher 1, D Watson 1, E O Mason Jr 1
PMCID: PMC262912  PMID: 8501225

Abstract

The increasing prevalence of penicillin-resistant Streptococcus pneumoniae requires antibiotic susceptibility tests that can be done with greater ease and reliability. We measured the MIC of penicillin for pneumococci by the tube macrodilution method with Mueller-Hinton broth (MHB), Haemophilus Test Medium (HTM), Todd-Hewitt broth with 0.5% yeast extract (THY), and MHB with 3% lysed horse blood (LHB). Eight (19%) and 6 (14%) of 42 pneumococcal isolates failed to generate turbid growth in MHB and HTM, respectively, whereas all pneumococcal isolates did so in THY and LHB. For those strains that replicated to turbidity, the mean MICs of penicillin were lower in MHB and HTM than in THY and LHB, with differences being significant (P < 0.05) for comparisons with LHB. Four isolates appeared to be penicillin susceptible in HTM but were actually moderately resistant in THY and LHB, and two isolates appeared to be moderately resistant but were resistant. A similar failure to detect resistance was seen with MHB. S. pneumoniae ATCC 49619, a moderately penicillin-resistant strain that has been proposed for quality control testing, gave variable results in MHB or THM and appeared to be susceptible to penicillin in some assays, whereas the MICs for S. pneumoniae ATCC 49619 in THY or LHB fell within a twofold dilution range, with geometric means of 0.16 and 0.18 micrograms/ml, respectively. Pneumococcal isolates thus may appear falsely susceptible to penicillin when tested in MHB or HTM. LHB remains the standard medium; however, because THY is an easily prepared clear medium that can be used in automated systems and appears to yield results similar to those obtained with LHB, THY deserves consideration for routine use.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Ford K. L., Mason E. O., Jr, Kaplan S. L., Lamberth L. B., Tillman J. Factors associated with middle ear isolates of Streptococcus pneumoniae resistant to penicillin in a children's hospital. J Pediatr. 1991 Dec;119(6):941–944. doi: 10.1016/s0022-3476(05)83050-1. [DOI] [PubMed] [Google Scholar]
  2. Jones R. N., Edson D. C. Antimicrobial susceptibility testing trends and accuracy in the United States. A review of the College of American Pathologists Microbiology Surveys, 1972-1989. Microbiology Resource Committee of the College of American Pathologists. Arch Pathol Lab Med. 1991 May;115(5):429–436. [PubMed] [Google Scholar]
  3. Jorgensen J. H., Doern G. V., Ferraro M. J., Knapp C. C., Swenson J. M., Washington J. A. Multicenter evaluation of the use of Haemophilus test medium for broth microdilution antimicrobial susceptibility testing of Streptococcus pneumoniae and development of quality control limits. J Clin Microbiol. 1992 Apr;30(4):961–966. doi: 10.1128/jcm.30.4.961-966.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Jorgensen J. H., Redding J. S., Maher L. A., Howell A. W. Improved medium for antimicrobial susceptibility testing of Haemophilus influenzae. J Clin Microbiol. 1987 Nov;25(11):2105–2113. doi: 10.1128/jcm.25.11.2105-2113.1987. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Mason E. O., Jr, Kaplan S. L., Lamberth L. B., Tillman J. Increased rate of isolation of penicillin-resistant Streptococcus pneumoniae in a children's hospital and in vitro susceptibilities to antibiotics of potential therapeutic use. Antimicrob Agents Chemother. 1992 Aug;36(8):1703–1707. doi: 10.1128/aac.36.8.1703. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Mendelman P. M., Wiley E. A., Stull T. L., Clausen C., Chaffin D. O., Onay O. Problems with current recommendations for susceptibility testing of Haemophilus influenzae. Antimicrob Agents Chemother. 1990 Aug;34(8):1480–1484. doi: 10.1128/aac.34.8.1480. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Musher D. M. Infections caused by Streptococcus pneumoniae: clinical spectrum, pathogenesis, immunity, and treatment. Clin Infect Dis. 1992 Apr;14(4):801–807. doi: 10.1093/clinids/14.4.801. [DOI] [PubMed] [Google Scholar]
  8. Spika J. S., Facklam R. R., Plikaytis B. D., Oxtoby M. J. Antimicrobial resistance of Streptococcus pneumoniae in the United States, 1979-1987. The Pneumococcal Surveillance Working Group. J Infect Dis. 1991 Jun;163(6):1273–1278. doi: 10.1093/infdis/163.6.1273. [DOI] [PubMed] [Google Scholar]

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