Related Experiment Video
Updated: Jul 27, 2026
08:30
One-day Workflow Scheme for Bacterial Pathogen Detection and Antimicrobial Resistance Testing from Blood Cultures
Published on: July 9, 2012
Penicillin tolerance in Arcanobacterium haemolyticum.
1Department of Infectious Diseases, Malmö General Hospital, University of Lund, Sweden.
The Journal of Infectious Diseases
|February 1, 1990
Summary
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.
More Related Videos
09:39A Platform of Anti-biofilm Assays Suited to the Exploration of Natural Compound Libraries
Published on: December 27, 2016
05:06Characterizing Multidrug Efflux Systems in Acinetobacter baumannii Using an Efflux-Deficient Bacterial Strain and a Single-Copy Gene Expression System
Published on: January 5, 2024
Related Concept Videos
01:23Pharmacokinetic–Pharmacodynamic Relationship: Influence of Elimination Half-Life on Effect Duration
Drug elimination from the body primarily occurs through metabolic and excretion pathways. Hepatic metabolism transforms lipophilic drugs into hydrophilic forms for excretion, typically via enzymatic processes classified as phase I (modification) and phase II (conjugation). Renal excretion eliminates drugs and metabolites through filtration and secretion in the kidneys. Impairment in liver or kidney function can hinder these processes, delaying drug clearance and extending the drug’s half-life.
01:30Development of Antibiotic Resistance
Antibiotic resistance is a major public health concern that arises when bacteria evolve mechanisms to withstand the effects of antibiotic treatments. This resistance can be intrinsic, acquired through genetic mutations, or transferred between bacteria via horizontal gene transfer. The development of antibiotic resistance poses significant challenges in treating bacterial infections and necessitates ongoing research to develop new therapeutic strategies.Intrinsic resistance occurs when bacterial...
01:27Production of Antibiotics
Penicillin, one of the earliest and most widely used antibiotics, is produced industrially by the filamentous fungus Penicillium chrysogenum. Large stirred-tank bioreactors ranging from tens to hundreds of thousands of liters maintain tightly controlled temperature, pH, and dissolved oxygen conditions to support fungal metabolism and maximize antibiotic yield. Penicillin is a secondary metabolite, synthesized primarily during the stationary growth phase, which requires a carefully managed...
01:25Mechanism of Antibiotic Resistance in MRSA
Antibiotic resistance in bacteria arises when microorganisms evolve the ability to withstand drugs designed to kill them or inhibit their growth, rendering once-effective treatments useless. This phenomenon, driven by genetic change and selection under antibiotic exposure, poses a profound threat to modern medicine. Mechanisms include drug-inactivating enzymes (e.g., β-lactamases), efflux pumps that eject antibiotics, mutations altering antibiotic targets, decreased drug uptake, and acquisition...
01:23Inhibitors of Gram-positive Cell Wall Synthesis
Bacterial cell walls are typically rigid structures composed mainly of peptidoglycan, a mesh-like polymer that provides mechanical strength and maintains cell shape. The synthesis of peptidoglycan is a crucial process in bacterial growth and serves as a primary target for many antibiotics.Mechanism of Action of Beta-Lactam AntibioticsBeta-lactam antibiotics, such as penicillin, inhibit peptidoglycan synthesis in actively growing cells. These antibiotics share a characteristic four-membered...
01:25Clinical Significance of Antibiotic Resistance
Methicillin-resistant Staphylococcus aureus (MRSA) presents a critical public health threat, arising from its capacity to resist β-lactam antibiotics due to acquisition of the mecA gene within the staphylococcal cassette chromosome mec (SCCmec). This gene encodes penicillin-binding protein 2a (PBP2a), which impairs binding efficacy of methicillin and other β-lactams. MRSA has evolved into distinct clonal lineages impacting humans and animals alike, reinforcing its significance within the One...