December 7, 2015 - MSK Infections

Question 1

Clostridium tetani

Answer 1

Gram positive bacilli

Look like “tennis rackets”

Can produce tatanospasmin which can cause toxicity. Should vaccinate patients against tetanus if they haven’t been.

Question 2

Management of Open Wounds

Answer 2

Intravenous antibiotics

Operative irrigation and debridement

Tetanus toxoid for tetanus-prone wounds

Question 3

Bone Scintigraphy (Scan)

Answer 3

A nuclear scanning test to find certain abnormalities in bone. It is primarily used to diagnose cancer, inflammation, damage from infections, etc.

Question 4

Curative vs Suppressive Treatments

Answer 4

Usually go for curative when joints become infected, but sometimes you may opt for a suppressive treatment.

For example, if a 90-year old man who is relatively immobile became infected, it wouldn’t make sense to perform surgery to replace the joint. The risks of surgery would be too great. Instead, he may be put on antibiotics for the rest of his life to prevent spread.

Question 5

Gonococcal Infections

Answer 5

Peak incidence is 15-30 years old.

Usually monoarticular (particularly knee)

Treatment is IV antibiotics for 48 hours, then oral antibiotics for 7 days.

Question 6

Group A Streptococcus

Answer 6

Gram positive cocci

Beta hemolytic

Can be aggressive

Question 7

Enbril

Answer 7

An anti-inflammatory drug

TNF-inhibitor

Question 8

Hip vs Knee Infection

Answer 8

The hip is deeper and is often much harder to tell if it is infected.

Question 9

CBC and Infection

Answer 9

Hemoglobin is often decreased during infection

WBC is often increased (but can be normal)

CRP and ESR will be elevated

Question 10

WBC Scan

Answer 10

Also called indium leukocyte imaging

White blood cells are removed from a patient, tagged with Indium-111 and then injected intravenously into the patient. The tagged leukocytes subsequently localize to areas of relatively new infection.

This is useful in differentiating conditions such as osteomyelitis.

Question 11

Glycocalyx

Answer 11

Is an external coating of bacteria with protective function, made mostly of polysaccharides. Can make it very difficult for antibiotics to penetrate.

Question 12

Risk Factors for MSK Infections

Answer 12

Immunocompromised

Malnourishment

Post-traumatic

Orthopedic surgery

Hospitalized patients

Patients with artificial joints

IV drug users

Question 13

The Most Common Joint in Septic Arthritis

Answer 13

Hip

Question 14

Routes of Bacterial Spread

Answer 14

Direct

Contiguous

Hematogenous

Question 15

Infected Artificial Joint

Answer 15

Most commonly caused by S. aureus, and most commonly affects the hip.

This is a surgical emergency.