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Pathways of Methicillin-Resistant Staphylococcus aureus in Animal Model: New Insights Regarding Public Health

Authors Hamza DA, Abd-Elsalam RM, Nader SM, Elhariri M, Elhelw R, El-Mahallawy HS

Received 3 March 2020

Accepted for publication 12 May 2020

Published 4 June 2020 Volume 2020:13 Pages 1593—1600


Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 2

Editor who approved publication: Dr Sahil Khanna

Dalia A Hamza,1 Reham M Abd-Elsalam,2 Sara M Nader,1 Mahmoud Elhariri,3 Rehab Elhelw,3 Heba S El-Mahallawy4

1Department of Zoonoses, Faculty of Veterinary Medicine, Cairo University, Giza, Egypt; 2Department of Pathology, Faculty of Veterinary Medicine, Cairo University, Giza, Egypt; 3Department of Microbiology, Faculty of Veterinary Medicine, Cairo University, Giza, Egypt; 4Department of Animal Hygiene, Zoonoses and Animal Behaviour and Management, Faculty of Veterinary Medicine, Suez Canal University, Ismailia, Egypt

Correspondence: Dalia A Hamza
Department of Zoonoses, Faculty of Veterinary Medicine, Cairo University, Giza 12211, Egypt
Tel +20 1 009701262
Fax +20 2 35725240

Background: Staphylococcus aureus is considered one of the major threats regarding food safety worldwide. Methicillin-resistant S. aureus (MRSA) strains in livestock, companion animals, and wild animals continue to be a potential risk to people working with them.
Aim: The current research aims to investigate the potential pathways of livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) strains in the body after oral infection using the experimental mouse model.
Methods: Seven groups of SPF male mice were purchased and housed. On day 1, six groups of mice were infected orally by the sterile gastric probe using 100 μL/mice of LA-MRSA bacterial suspension (1 × 108 colony-forming units (CFU)/mL). The remaining group was kept as negative controls. Over 15 days, these animals have been monitored. Fresh fecal samples were screened for LA-MRSA at day 0, day 7 and day 14 following oral administration of MRSA strains. All animals were sacrificed at day 15, and internal organs (liver, lung, kidney, and intestine) were harvested aseptically and divided into two sections. The first part was histopathologically investigated, while the other half has been tested for LA-MRSA re-isolation.
Result: The oral challenge of mice by MRSA strains showed that MRSA was re-isolated from feces and intestines of all inoculated mice groups and from internal organs (liver, lung, kidney and intestine) of most mice. Results were confirmed by the detection of the bacteria in gram-stained tissue sections and changes in H&E-stained histopathological tissue sections from these organs.
Conclusion: Data from the present study indicate the possible colonization of livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) in internal organs following oral infection and thus posing a risk for food-borne infection of MRSA. Infected animals could pass LA-MRSA through feces again, resulting in increased dispersion and environmental contamination.

Keywords: Staphylococcus aureus, MRSA, animal model, mice, oral challenge, PCR, histopathology

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