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Subcutaneous Infection of Methicillin Resistant Staphylococcus Aureus MRSA
Published on: February 9, 2011
Canine pyoderma: mecA persists autogenous bacterin formulation from meticillin-resistant Staphylococcus
Anette Loeffler1, Claire Scott1,2, Siân-Marie Frosini1
1Royal Veterinary College, Clinical Science and Services.
Objective:
Autogenous Staphylococcus pseudintermedius bacterins can reduce prescribing of antimicrobials in the management of canine recurrent pyoderma. However, increasing prevalence of meticillin-resistant, mecA-positive S. pseudintermedius (MRSP) raises concern over dispersal of mecA through bacterin therapy. We investigated the presence and integrity of mecA in bacterin formulations after manufacturing.
Material And Methods:
Twenty clinical isolates (12 MRSP, 7 MR-S. aureus, 1 meticillin-susceptible SP) were investigated. Pellets from overnight growth were washed 3 times with 0.5 % phenol saline, followed by addition of 0.1 ml 10 % formal-saline to 10 ml phenol-saline. Sterility was confirmed, and DNA extracted using both a standard genomic extraction kit and one recommended for formalin-fixed tissue samples (FFPE). The presence of mecA was determined after PCR and its integrity examined in 5 randomly selected samples after sequencing.
Results:
In all bacterins from meticillin-resistant isolates, mecA was detected following FFPE extraction; products aligned fully to a reported mecA sequence. After standard DNA extraction, mecA was seen in 16/19 samples.
Conclusion:
Persistence of mecA in MRSP bacterins suggests that dispersal of this important resistance mediator through therapy may be possible. While the ability of skin bacteria to uptake naked DNA remains unclear, it seems prudent to only formulate autogenous bacterins from mecA-negative S. pseudintermedius to avoid unnecessary spread of mecA.
Insights
Meticillin-resistant Staphylococcus pseudintermedius (MRSP) bacterins may spread the mecA gene. Researchers found mecA persisted in bacterins, suggesting caution when formulating treatments for canine pyoderma to prevent resistance spread.
Area of Science:
- Veterinary Microbiology
- Antimicrobial Resistance
- Canine Health
Background:
- Autogenous bacterins for canine pyoderma can reduce antimicrobial use.
- Increasing prevalence of meticillin-resistant Staphylococcus pseudintermedius (MRSP) raises concerns about resistance gene dispersal.
- The presence and integrity of the mecA gene in bacterin formulations require investigation.
Purpose of the Study:
- To investigate the presence and integrity of the mecA gene in autogenous bacterin formulations after manufacturing.
- To assess the potential for mecA gene dispersal through bacterin therapy in canine pyoderma management.
Main Methods:
- Twenty clinical isolates, including MRSP and MR-Staphylococcus aureus, were processed.
- Bacterial pellets underwent washing and treatment with phenol saline and formalin.
- DNA was extracted using standard and FFPE-recommended kits, followed by PCR for mecA detection and sequencing.
Main Results:
- The mecA gene was detected in all bacterins derived from meticillin-resistant isolates using FFPE extraction.
- Sequencing confirmed the integrity of the mecA gene in selected samples.
- mecA was detected in 16 out of 19 samples following standard DNA extraction.
Conclusions:
- The persistence of the mecA gene in MRSP bacterins indicates a potential for spreading this antimicrobial resistance mediator.
- Formulating autogenous bacterins exclusively from mecA-negative Staphylococcus pseudintermedius is advisable.
- This precaution aims to prevent the unnecessary dissemination of the mecA gene in veterinary settings.
