Osteomyelitis Flashcards
(21 cards)
What is the most likely pathogenic organism in children that causes osteomyelitis?
Staphylococcus aureus
most common cause of acute haematogenous osteomyelitis in children, including in the calcaneus. Methicillin-sensitive S. aureus (MSSA) is more common than MRSA in the UK paediatric population.
What is the most common route of infection in osteomyelitis?
Blood borne
In children, osteomyelitis is most frequently caused by haematogenous spread of infection. Bacteria enter through the bloodstream and localise in the metaphysis due to the rich vascular supply
What is the name of the anatomical structure affected by Sever’s disease?
Epiphyseal growth plate
Sever’s disease is a traction apophysitis of the calcaneal growth plate, often affecting children aged 8–14, especially those active in sport
What is the name given to the dead bone and the reactive new bone found in chronic osteomyelitis cases?
Dead bone: Sequestrum
Reactive bone: Involucrum
A sequestrum is a piece of necrotic bone separated from living bone, while an involucrum is new bone formation surrounding a sequestrum.
Explain why potassium clavulanate is added to Amoxicillin in treatment for osteomyelitis
Potassium clavulanate is a β-lactamase inhibitor. It is added to amoxicillin (as co-amoxiclav) to prevent bacterial enzymes from degrading the β-lactam ring, thereby extending the antibiotic’s spectrum to cover β-lactamase-producing organisms.
A person with osteomyelitis had surgery and a bone sample sent for histology. What are the predominant cells seen between the bone trabeculae?
Neutrophils
In acute osteomyelitis, the predominant infiltrate is of neutrophils, indicating a bacterial infection.
Why in children does osteomyelitis tend to develop at the metaphysis of bones?
The metaphysis has slow, turbulent blood flow in the capillary loops, allowing bacteria to lodge easily.
The phagocytic activity is lower in this region compared to other parts of bone.
Sever’s disease
Sever’s disease: A self-limiting inflammatory condition of the calcaneal growth plate in children; traction apophysitis. Overuse injury of growth plate at heel, common in growing active children.
Lymphangitis:
Lymphangitis: Inflammation of the lymphatic channels, often due to spreading bacterial infection.
Erythematous
Erythematous: Reddening of the skin due to capillary dilation, typically a sign of inflammation.
Pyrexical
Pyrexical: Having a fever (elevated body temperature).
Apophysis
Apophysis: A bony outgrowth where tendons attach, usually a secondary ossification centre.
Osteomyelitis
Osteomyelitis: Infection of the bone, often caused by bacteria like Staphylococcus aureus.
Povidone-iodine fabric dressing
Povidone-iodine fabric dressing: A dressing impregnated with iodine, used as an antiseptic to prevent infection
Flucloxacillin
Flucloxacillin: A β-lactam antibiotic effective against Gram-positive organisms, especially MSSA.
Fusidic acid
Fusidic acid: A protein synthesis inhibitor used against Gram-positive organisms, often in combination therapy.
Os calcis
Os calcis: Another name for the calcaneus, the heel bone.
Osteomyelitis Pathophysiology
Osteomyelitis Pathophysiology: Most common in metaphysis; symptoms include fever, pain, swelling. Diagnosis via blood tests, imaging (MRI), cultures.
Antibiotic Mechanisms of the following:
- Flucloxacillin
- Co-amoxiclav
- Fusidic acid
Antibiotic Mechanisms:
- Flucloxacillin: Inhibits bacterial cell wall synthesis.
- Co-amoxiclav: Combines β-lactam antibiotic with enzyme inhibitor(Clavulanic acid)
- Fusidic acid: Inhibits bacterial protein synthesis.
Normal/healthy Epiphyseal Growth Plate Physiology
Epiphyseal Growth Plate Physiology: Responsible for longitudinal bone growth; susceptible to trauma and infection due to vascularity.
What kind of abscess seen in osteomyelitis
Brodie’s abscess
