Infection

Question 1

Hematogenous Osteomyelitis in (adults/children) occurs in the Metaphysis because

Answer 1

Children; hairpin turns of metaphyseal blood vessels slow blood flow, allowing bacteria to grow

Question 2

Hematogenous Osteomyelitis in (adults/children) occurs in vertebral bodies and joints

Answer 2

Adults (no physeal barrier)

Question 3

In children, the growth plate (physis) will serve as a barrier to infection, but even before skeletal maturity, Acute Osteomyelitis CAN spread to which select joints

Answer 3

Ankle (distal Fibula)
Elbow (Radial neck)
Shoulder (proximal Humerus)
Hip (proximal Femur)

*note that ALL are sites of RAPIDLY growing physes

Question 4

Clinical presentation of hematogenous osteomyelitis

Answer 4

Pain/tenderness
Fever
Elevated ESR and CRP

Question 5

Radiographic findings of osteomyelitis

Answer 5

1. periosteal elevation/luncency
2. Usually at major joints

• Takes 1-2 weeks to show changes on x-ray

Question 6

What are the common causative organisms of osteomyelitis?

Answer 6

1. Native joints: Staph aureus (gram +, catalase +, coagulase +)
2. Implant joints: Staph epi (gram+, catalase +, coagulase -)
3. Sickle cells: Salmonella (gram -)

Question 7

Bacterial inoculation of rapidly growing joints (Hips and Knees) due to high blood supply, and thus increased possibility for bacterial seeding; Sternoclavicular joint can also be affected in IV drug users

Answer 7

Infectious (Septic) Arthritis

Question 8

How is septic arthritis diagnosed?

Answer 8

1. Exam findings: red, swollen, painful joint
2. Joint aspiration
   - WBC >50,000
   - High PMN %

Question 9

Tx for septic arthritis

Answer 9

surgical (irrigation & debridement; hip replacement)

Question 10

What are the common causative organisms of septic arthritis?

Answer 10

1. Staph aureus

2. Neisseria gonorrhoaea

Question 11

What are the common causative organisms of prosthetic joint infection?

Answer 11

1. staph. epidermidis (coag -)

2. P. acnes (only in shoulder replacement)

Question 12

What algorithm can you use to evaluate aspirated synovial fluid in the setting of Joint Pain?

Answer 12

1) Blood? Yes (trauma, coagulopathy, tumor.) or No (next step)
2) If no, WBC >2K? Yes (inflammatory arthritis or septic arthritis (WBC >20K)) or No (trauma, osteoarthritis, AVN)
3) If yes to #2, test for crystals (rule out gout)

Question 13

Pertinent Gram-negative ZOONOTIC rods for MSK infections

Answer 13

Brucella
Francisella
Pasteurella
Bartonella

“-ellas”

Question 14

Pertinent Gram-positive ZOONOTIC rod for MSK infections

Answer 14

Bacillus anthracis

Question 15

gram - zoonotic (cow, sheep, goat) rod transmitted through ingestion of contaminated milk (unpasteurized) or skin (butchering products)

Answer 15

Brucella

Question 16

Brucella is facultative intracellular bacteria that survives within_____ and forms ______

Answer 16

macrophages; granulomas

Question 17

What are the clinical and lab findings of brucella infection?

Answer 17

1. Fever
2. General Lymphadenopathy
3. Splenomegaly
4. Sacroiliac joint tenderness (lower back pain)
5. Elevated WBCs, PMNs
6. Elevated liver enzymes

Question 18

gram - zoonotic (rabbit, deer) rod transmitted by ticks/flies or cutaneous exposure to animal tissue

Answer 18

Francisella tularensis

Question 19

F. tularensis has a very low infectious dose and therefore can be a potential

Answer 19

bioterrorism agent

Question 20

What are the clinical and lab findings of tularemia?

Answer 20

1. Fever
2. Non-healing ulcerated lesion
3. Painful axillary lymphadenopathy
4. Elevated WBCs, PMNs
5. NORMAL liver enzymes

Question 21

F. Tularensis grows within_____ and forms ______

Answer 21

macrophages; granulomas

Question 22

Zoonotic bacteria associated with Granuloma formation

Answer 22

Brucella

Francisella tularensis

Question 23

Treatment for Brucella and F. tularensis

Answer 23

Doxycycline, Streptomycin

Question 24

gram - zoonotic (dogs, cats) rod transmitted by dog or cat bites; associated with complications such as osteomyelitis, endocarditis, meningitis); commonly seen in immunocompromised/diabetic patients

Answer 24

Pasteurella multocida

Question 25

Zoonotic bacteria associated with bipolar staining (its core stains lighter than the edges) of capsule and no growth on MacConkey Agar

Answer 25

Pasteurella multocida

Question 26

gram - zoonotic (cats) rod transmitted by cat scratches/bites; low virulence so usually self-limited

Answer 26

Bartonella henslea

Question 27

Clinical findings of Bartonella infection

Answer 27

- fever | - Lymphadenopathy along scratch

Question 28

Clinical finding for Bartonella in Immunocompromised hosts (AIDS)

Answer 28

Bacillary angiomatosis

Question 29

Gram-positive zoonotic rod; SPORE-FORMING; human infection acquired via cutaneous exposure, inhalation/ingestion

Answer 29

Bacillus anthracis

Question 30

What cutaneous disease is caused by Bacillus anthracis?

Answer 30

Pigmented eschar (scab) or necrotic lesion

Question 31

What inhalation disease is caused by Bacillus anthracis?

Answer 31

Wool-sorters' disease (hemorrhagic mediastinitis, pleural effusions, septic shock)

Question 32

A SPIROCHETE bacteria that is transmitted by black-legged TICKS in spring/summer; causes lyme disease (borreliosis)

Answer 32

Borrelia burgdorferi

Question 33

Symptoms/clinical presentation of lyme borreliosis

Answer 33

1. Fever, chills 2. ERYTHEMA MIGRANS (Bulls-eye rash) 3. Facial palsy 4. arthritis/joint pain 5. swollen knee

Question 34

How to diagnose Lyme Disease

Answer 34

ELISA | Western Blot

Question 35

Treatment for Lyme Disease

Answer 35

Doxycycline | Amoxicillin

Question 36

Which zoonotic bacteria are associated with ticks

Answer 36

Francisella tularensis | Borrelia burgdorferi

Question 37

+ssRNA enveloped viruses that cause Dengue infection; insect-borne (mosquitoes)

Answer 37

Flavivirus

Question 38

Severe fever illness with rash and "breakbone fever" (severe muscle/joint pain that feels like a broken bone); acute but self-limiting

Answer 38

Dengue Fever

Question 39

Progression of Dengue fever; causes hemorrhagic shock

Answer 39

Dengue Hemorrhagic Fever

Question 40

How does an infection of a DIFFERENT Dengue serotype result in a worsening of symptoms

Answer 40

Antibodies to the previous serotype DON'T neutralize the different serotype--> Activation of complement --> cytokine storm--> Shock and Hemorrhage

Question 41

Zika and yellow fever viruses are what type of viruses?

Answer 41

flaviviruses

Question 42

Coagulase-negative Staphylocci

Answer 42

S. epidermidis | S. saprophyticus

Question 43

Coagulase-positive Staphylocci

Answer 43

S. aureus

Question 44

S. aureus shows as ___________ on Mannitol Salt Agar

Answer 44

Gold/yellow

Question 45

Findings of normal synovial fluid

Answer 45

1. Clear 2. <200 PMNs 3. glucose levels equal to that in blood

Question 46

Findings of synovial fluid during infection

Answer 46

1. Cloudy 2. >20,000 PMNs 3. 1/4 glucose level of blood

Question 47

Findings of normal synovial fluid in rheumatoid arthritis

Answer 47

1. Opalescent (less cloudy) 2. 200-20,000 PMNs 3. 1/2 glucose level of blood

Question 48

Form of TB that occurs outside the lungs whereby disease is seen in the vertebrae, a kind of tuberculous arthritis of the intervertebral joints

Answer 48

Pott's disease (aka. Spinal TB)

Question 49

Gram-negative rod in GI tract; Lactose negative and H2S producer; Typhoid and Non-Typhoid species; can seed in bone marrow of SICKLE CELL patients early in childhood

Answer 49

Salmonella

Question 50

IV drug use, catheters, open fractures, and sickle cell disease are risk factors of

Answer 50

Osteomyelitis