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Penicillin tolerance in Arcanobacterium haemolyticum

M Nyman1, G Banck, M Thore

  • 1Department of Infectious Diseases, Malmö General Hospital, University of Lund, Sweden.

The Journal of Infectious Diseases
|February 1, 1990
PubMed

Insights

Arcanobacterium haemolyticum causes tonsillitis but is often tolerant to penicillin. This penicillin tolerance suggests that phenoxymethylpenicillin may be ineffective for eradicating this bacterium from the pharynx.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Pharmacology

Background:

  • Arcanobacterium haemolyticum is a pathogen causing tonsillitis with exanthema.
  • Phenoxymethylpenicillin is often prescribed for bacterial pharyngitis.
  • Previous studies indicate phenoxymethylpenicillin fails to eradicate A. haemolyticum from the pharynx despite low minimum inhibitory concentrations.

Purpose of the Study:

  • To investigate the phenomenon of penicillin tolerance in recent clinical isolates of Arcanobacterium haemolyticum.
  • To determine the prevalence and degree of penicillin tolerance in A. haemolyticum.
  • To assess the clinical implications of penicillin tolerance for A. haemolyticum infections.

Main Methods:

  • Disk diffusion screening tests were employed to assess penicillin tolerance.
  • Pour plate assays were utilized to quantify penicillin tolerance.
  • Macrobroth dilution methods determined minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs).
  • Antibiotic kill kinetics were analyzed for select isolates.

Main Results:

  • Penicillin tolerance was detected in 38 out of 40 clinical isolates using the disk diffusion assay.
  • The pour plate assay revealed all 40 isolates were tolerant, with 34 exhibiting high tolerance.
  • Macrobroth dilution assays confirmed the presence of the tolerant phenotype.

Conclusions:

  • Arcanobacterium haemolyticum frequently exhibits a penicillin-tolerant phenotype.
  • This tolerance suggests that phenoxymethylpenicillin treatment may be ineffective for eradicating A. haemolyticum from the pharynx.
  • Further research into alternative treatment strategies for A. haemolyticum infections is warranted.

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