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Journal article
Reliability of disc diffusion testing and molecular epidemiology of penicillin-susceptible Staphylococcus aureus bacteraemia
Journal of antimicrobial chemotherapy, dkaf187
2025
PMID: 40492523
Abstract
Background
Recent studies have reported an increasing prevalence of penicillin-susceptible Staphylococcus aureus (PSSA) worldwide. The reliability of disc diffusion testing for detecting penicillin-resistance has been questioned, and the molecular epidemiology of PSSA has not been studied to the same extent as that of MRSA strains.
Objectives
To investigate the reliability of the disc diffusion method for detecting penicillin-resistance in S. aureus, and to examine the prevalence and molecular epidemiology of PSSA in bloodstream infections.
Methods
A total of 258 bacteraemic isolates obtained from one geographic region in Sweden during 2018–2019 were analysed using the disc diffusion test to detect penicillin-resistance, and genome sequenced to examine the prevalence of the blaZ gene and the molecular epidemiology of PSSA.
Results
Phenotypic susceptibility to penicillin correlated strongly with the absence of the blaZ gene, with nearly 98% concordance. The prevalence of PSSA among patients with bacteraemia was 35.1%, highlighting the need for penicillin-susceptibility testing. Additionally, population structure analyses revealed substantial genetic diversity, underscoring the complexity of the PSSA epidemiology. The PSSA belonged to diverse clonal lineages, with CC5 and CC45 dominating our cohort, similar to findings in Spain, Australia, and other parts of Sweden. However, our study revealed a higher prevalence of CC12 compared with other regions, underscoring the importance of local epidemiological surveillance.
Conclusions
These findings validate the reliability of EUCAST’s disc diffusion method, showing a high prevalence of PSSA, and provide insight into the genetic underpinnings of penicillin-susceptibility in S. aureus.
Details
- Title
- Reliability of disc diffusion testing and molecular epidemiology of penicillin-susceptible Staphylococcus aureus bacteraemia
- Authors/Creators
- Pernilla Kihlberg - Örebro UniversityThor Bech Johannesen - Veterinary Biological and Research InstituteMarc Stegger - Murdoch UniversitySara Cajander - Örebro UniversityBo Soderquist - Örebro University
- Publication Details
- Journal of antimicrobial chemotherapy, dkaf187
- Publisher
- Oxford University Press on behalf of British Society for Antimicrobial Chemotherapy.
- Number of pages
- 7
- Grant note
- RFR-931422 / Regionala Forskningsradet Uppsala/Orebro OLL-982875; OLL-936003; OLL-933344 / Research Committee of Region Orebro Lan OLL-985410; OLL-999643 / Region Orebro Lan
- Identifiers
- 991005788079407891
- Copyright
- © The Author(s) 2025.
- Murdoch Affiliation
- Harry Butler Institute
- Language
- English
- Resource Type
- Journal article
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- Collaboration types
- Domestic collaboration
- International collaboration
- Citation topics
- 1 Clinical & Life Sciences
- 1.23 Antibiotics & Antimicrobials
- 1.23.173 MRSA and VRE
- Web Of Science research areas
- Infectious Diseases
- Microbiology
- Pharmacology & Pharmacy
- ESI research areas
- Pharmacology & Toxicology