Subcutaneous Infection of Methicillin Resistant Staphylococcus Aureus (MRSA)

Summary

Murine skin and soft tissue infection model is utilized for assessing the virulence function of methicillin resistant Staphylococcus aureus (MRSA) and the host immunological responses. Here, we presented a subcutaneous infection model for skin and soft tissue infection.

Abstract

MRSA is a worldwide threat to public health, and MRSA skin and soft-tissue infections now account for more than half of all soft-tissue infections in the United States. Among soft-tissue infections, myositis, pyomyositis, and necrotizing fasciitis have been increasingly reported in association with MRSA arising from the community. To understand the interplay between MRSA and host immunity leading to more severe infection, the availability of animal models is critical, permitting the study of host and bacterial factors. Several infection models have been introduced to assess the pathogenesis of S. aureus during superficial skin infection. Here, we describe a subcutaneous infection model that examines the skin, subcutaneous, and muscle pathologies.

Protocol

1. Preparing the MRSA for Infection (two Days Prior to Infection)

1. Inoculate a loopful of MRSA from a stock culture to a blood agar (Trypticase Soy Agar (TSA)) plate.
2. Check the hemolysis phenotype (a clear zone around each colony) on the blood agar plate.
3. Pick a colony that has a hemolytic phenotype that is consistent with other experiments.
4. Inoculate the colony into 3 mL Todd Hewitt Broth (THB),with the appropriated antibiotic when necessary, in a 15 mL snap-capped tube.
5. Incubate at 37°C overnight with shaking at 220 rpm.

2. Preparing the Mice for Infection (one Day Prior to In....

Discussion

1. The murine skin and soft tissue infection model is a powerful tool for in vivo virulence assessment of a pathogen. The pathogenicity of S. aureus in skin and soft tissue infection may vary depending on a number of parameters. These include inoculum size, bacterial growth phase, depth of inoculation, age of mice, and the mouse genetic background ^{7, 8}. When examining the virulence function using this model, it is critical to control for these parameters to ensure that results will be consistent. We have .......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
THB	VWR international	95025-314
DPBS	Invitrogen	21-031-CV
1 ml syringe	BD Biosciences	309602
27G1/2 needle	BD Biosciences	305109
Sheep Blood Agar (TSA)	VWR international	90004-328