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Updated: May 17, 2026
A Precise Pathogen Delivery and Recovery System for Murine Models of Secondary Bacterial Pneumonia
Published on: September 21, 2019
A Time Course for Susceptibility to Staphylococcus aureus Respiratory Infection during Influenza in a Swine Model
Elizabeth A Smith1, Sandeep R P Kumar, Jagadeeswaran Deventhiran
1Department of Dairy Science, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
Abstract:
Bacterial superinfections following influenza A virus (IAV) are predominant causes of morbidity in humans. The recent emergence of methicillin-resistant Staphylococcus aureus (MRSA) and highly virulent IAV strains has reduced treatment options. Development of an appropriate animal model to study secondary S. aureus infections may provide important information regarding disease pathogenesis. Pigs are natural hosts to both IAV and S. aureus and have respiratory physiology and immune response comparable to humans. To establish a time course of susceptibility to S. aureus after IAV infection, nursery pigs infected intranasally with IAV were challenged with MRSA at different time points. Lung pathology scores and MRSA CFU were evaluated in dual-infected animals after IAV infection. Flow cytometric analysis of bronchoalveolar lavage fluid indicated differences between treatments. These results demonstrate the appropriateness of an intranasal challenge model in nursery pigs for studying the pathogenesis of IAV and S. aureus coinfection and provide insights into the timeframe for susceptibility of IAV-infected pigs to secondary S. aureus infection.
Insights
Secondary bacterial infections after influenza A virus (IAV) are serious. This study shows pigs are a good model for studying IAV and methicillin-resistant Staphylococcus aureus (MRSA) coinfections and their susceptibility timing.
Area of Science:
- Veterinary Medicine
- Infectious Disease
- Microbiology
Background:
- Bacterial superinfections, particularly with methicillin-resistant Staphylococcus aureus (MRSA), significantly increase morbidity and mortality following influenza A virus (IAV) infection.
- Limited treatment options due to virulent IAV strains and antibiotic-resistant bacteria necessitate better understanding of disease pathogenesis.
- Pigs, natural hosts to both IAV and S. aureus, offer a relevant animal model due to physiological and immunological similarities to humans.
Purpose of the Study:
- To establish and validate a pig model for studying the pathogenesis of IAV and S. aureus coinfection.
- To determine the time course of susceptibility to secondary S. aureus infection following IAV challenge in pigs.
- To investigate the impact of IAV infection on susceptibility to MRSA.
Main Methods:
- Nursery pigs were infected intranasally with IAV.
- Following IAV infection, pigs were challenged with MRSA at various time points.
- Lung pathology, bacterial load (MRSA colony-forming units), and immune cell populations in bronchoalveolar lavage fluid were analyzed.
Main Results:
- The intranasal challenge model in pigs effectively replicated IAV and S. aureus coinfection.
- Lung pathology scores and MRSA bacterial loads were evaluated in dual-infected pigs.
- Flow cytometry revealed differences in immune cell responses between treatment groups.
Conclusions:
- The study validates the use of nursery pigs as an appropriate model for investigating IAV and S. aureus coinfection.
- The findings provide crucial insights into the temporal window of increased susceptibility to secondary S. aureus infections post-IAV.
- This model aids in understanding the pathogenesis of severe respiratory coinfections and informs potential therapeutic strategies.
