Identification of new phages to type Staphylococcus aureus strains and comparison with a genotypic method
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Published on: November 4, 2016
C de Gialluly1, J Loulergue, G Bruant
1Laboratoire de bactériologie et d'hygiène hospitalière, Centre Hospitalier Universitaire, 37044 Tours, Cedex 1, France. c.degialluly@chu-tours.fr
Abstract:
The aim of this study was to optimize the epidemiological monitoring of strains of Staphylococcus aureus, a major cause of hospital-acquired infections. From September to December 1998 47 S. aureus strains isolated from swabs taken from orthopaedic and trauma patients were in studied. Thirty-five isolates were sensitive to methicillin (MSSA) and 12 were methicillin-resistant (MRSA). Ten of the 47 isolates could not be phage-typed using the international set of typing phages: five of these isolates were MSSA and five were MRSA. These MRSA isolates, which were also not typeable by the phages currently recommended for phage-typing MRSA, were lysed by locally isolated experimental phages 584 and 1814. Phage 1814 lysed the gentamicin-resistant MRSA and phage 584 acted on the gentamicin-sensitive MRSA. Both new phages were inactive against the methicillin-sensitive isolates. Cloning of certain isolates was confirmed by macrorestriction genomic profiles obtained by pulsed-field gel electrophoresis analysis (PFGE). The results showed good discriminatory ability of antibiotic-resistance pattern phenotyping and phage-typing when the phages used were adapted to epidemic-associated MRSA strains.
Insights
New experimental phages effectively identified difficult-to-type methicillin-resistant Staphylococcus aureus (MRSA) strains. This optimizes epidemiological monitoring for hospital-acquired infections caused by MRSA.
Area of Science:
- Microbiology
- Epidemiology
- Infectious Diseases
Background:
- Staphylococcus aureus is a significant cause of hospital-acquired infections.
- Effective epidemiological monitoring is crucial for controlling the spread of resistant strains.
- Current phage typing methods struggle with certain Staphylococcus aureus isolates.
Purpose of the Study:
- To optimize epidemiological monitoring of Staphylococcus aureus strains.
- To identify novel phages for typing difficult-to-characterize methicillin-resistant Staphylococcus aureus (MRSA) isolates.
- To evaluate the discriminatory power of antibiotic resistance phenotyping and phage typing.
Main Methods:
- Studied 47 Staphylococcus aureus strains from orthopaedic and trauma patients.
- Utilized international phage typing sets and locally isolated experimental phages (584 and 1814).
- Confirmed isolate clonality using pulsed-field gel electrophoresis (PFGE) and antibiotic resistance pattern phenotyping.
Main Results:
- Ten isolates (five MSSA, five MRSA) were untypeable with standard international phages.
- Experimental phages 584 and 1814 lysed these previously untypeable MRSA strains.
- Phage 1814 targeted gentamicin-resistant MRSA, while phage 584 targeted gentamicin-sensitive MRSA.
- New phages were inactive against methicillin-sensitive isolates.
Conclusions:
- Locally isolated experimental phages show promise for typing challenging MRSA strains.
- Optimized phage typing, adapted to epidemic strains, enhances discriminatory ability.
- Improved MRSA typing aids in controlling hospital-acquired infections.
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