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Knee joint infections with Staphylococcus aureus and Micrococcus species
Abstract:
In rabbit knees 600 Staphylococcus aureus organisms produced progressive infection in 50 per cent of the knees injected, whereas 5.3 times 10-7 Micrococcus species caused only transient colonization of the joints. Methicillin, cephacetrile, and clindamycin administered before injection of the staphylococci gave protection. Stainless-steel particles in the knee did not increase susceptibility to infection from injected micrococci but did make established micrococcal infections more persistent. Knees containing steel debris failed to become infected during prolonged staphylococcal bacteremia. Injected autologous blood, either fresh or three days old, did not increase susceptibility to infection. Large doses of steroids, given systemically or intraarticularly, decreased resistance to micrococcal infection and increased the destruction caused by infection due to this organism.
Insights
Staphylococcus aureus caused progressive knee infections in rabbits, while Micrococcus species only transiently colonized joints. Antibiotics like methicillin protected against infection, but steroids decreased resistance, worsening outcomes.
Area of Science:
- Orthopedics
- Infectious Diseases
- Microbiology
Background:
- Understanding factors influencing joint infection susceptibility is crucial for preventing and treating orthopedic infections.
- Staphylococcus aureus and Micrococcus species are common bacteria implicated in joint infections.
Purpose of the Study:
- To investigate the infectivity of Staphylococcus aureus and Micrococcus species in rabbit knees.
- To evaluate the impact of antibiotics, stainless-steel particles, autologous blood, and steroids on joint infection development and persistence.
Main Methods:
- Rabbit knees were injected with varying bacterial concentrations (Staphylococcus aureus, Micrococcus species).
- The effects of pre-injection antibiotics (methicillin, cephacetrile, clindamycin), stainless-steel particles, autologous blood, and steroids (systemic and intraarticular) on infection were assessed.
Main Results:
- Staphylococcus aureus caused progressive infection in 50% of knees, whereas Micrococcus species resulted in transient colonization.
- Antibiotics administered before bacterial injection provided protection against infection.
- Stainless-steel particles did not increase susceptibility but prolonged existing Micrococcus infections and prevented Staphylococcus aureus infection during bacteremia.
- Steroids decreased resistance to Micrococcus infection and exacerbated infection-related destruction.
Conclusions:
- Staphylococcus aureus is more virulent than Micrococcus species in inducing rabbit knee infections.
- Antibiotics are effective in preventing Staphylococcus aureus knee infections, while steroids impair the host's defense mechanisms against Micrococcus species.