Bone Infection - Block 1

Question 1

RF of bone infection?

Answer 1

1. Diabetes (DFI)
2. Peripheral vascular disease

Question 2

Complications of bone infection?

Answer 2

1. Amputation
2. Bone deformity

Question 3

What is the difference between OM and infectious arthritis?

Answer 3

OM: infection of bone
Infectious/septic arthritis: inflammation of the joint cavity

Question 4

Acute vs chronic OM?

Answer 4

Acute: <1week
Chronic: >1 month

Question 5

What are the types of OM?

Answer 5

1. Hematogenous
2. Contiguous
3. Vascular insufficiency
4. Direct inoculation

Question 6

What is hematogenous OM?

Answer 6

Spread via bloodstream to the bone:
* Lumbar and thoracic vertebrae -> vertebral osteomyelitis
* Common in >50YO
* Staphylococci spp.

Question 7

What is contiguous OM?

Answer 7

Shares a common border/adjacent infection reach to the bone (untreated DFI wound):
* Polymicrobial infections
* Staphylococci spp.

Question 8

What is vascular insufficiency OM?

Answer 8

Polymicrobial infection (e.g. sacrum wounds, DFI)

Question 9

What is direct inoculation OM?

Answer 9

Trauma, puncture wound, surgery:
* Step, S. epidermis, E.coli, P. aeruginosa

Question 10

Sites of hematogenous OM?

Answer 10

1. Long bones and joints
2. Vertebrae

Question 11

Sites of contiguous OM?

Answer 11

Foot in DMF, femur, tibia, and mandible

Question 12

Sites of direct inoculation?

Answer 12

Foot

Question 13

Sites of vascular insufficiency?

Answer 13

Sacrum wound, feet, and toes

Question 14

Common pathogens of OM in adults? Children

Answer 14

Adults: S. aureus

less than 4 YO: Kingella kingae
>4 YO: S. aureus

Question 14

Presentations of vertebral OM?

Answer 14

1. Constant back pain
2. Nuerological complication if infection compressess spinal cord

Question 15

Clinical presentation of direct inoculation OM?

Answer 15

S/swithin 1 month from surgery or bone trauma

Question 16

Clinical presentation of contiguous spread OM?

Answer 16

1. Localized tenderness, warmth, edema, erythema
2. In patients with vascular insufficiency

Question 17

GOld standard of OM diagnosis?

Answer 17

MRI: as early as 1 day after onset of infection

Question 18

Lab abnormalities of OM?

Answer 18

1. Elevated WBC
2. Elevate ESR and CRP (more sensitive)
3. Bone cultures
4. Blood culture is + in hematogenous

Question 19

What location is most common for contiguous osteomyelitis to occur in adults?

Answer 19

Foot

Question 20

Consideration to treat S. aureus OM?

Answer 20

• 10% -> MRSA -> vancomycin and daptomycin (alt)
• MSSA -> 1st gen cephalosporin (cefazolin)
• Pediatric -> Clindamycin

Question 21

How do you get adequate drug into the bone?

Answer 21

• High doses with adj of weight and renal/hepatic function
• Empiric therapy

Question 22

Tx for adult OM?

Answer 22

S. aureus: Vanc TDM or Daptomycil 6-10 mg/kg/day
OR
Cefazolin (no risk for MRSA)

Question 23

Vascular insufficiency tx?

Answer 23

G-: Vancomycin + ceftriaxone 2 g IV Q24H

Question 24

IV drug use OM tx?

Answer 24

MRSA and P. aeruginosa: Vancomycin + ciprofloxacin, ceftazidime, or cefepime

Question 25

Postop/trauma OM Tx?

Answer 25

MRSA and Pseudomonas: Vanc + Cefepime

Question 26

Necrotic OM Tx?

Answer 26

MRSA, Pseudomonas, anaerobes: * Vancomycin + Cefepime or ceftazidime or cefepime PLUS metronidazole 500 mg IV Q8 or clindamycin 900 IV Q8 **OR** * Vancomycin + zosyn or merrem (meripenum)

Question 27

Newborn OM tx?

Answer 27

S. aureus, S. pyogenes, E. coli: Cefazolin

Question 28

Children ≤ 3 years old OM tx?

Answer 28

K. kingae: cefazolin, cefuroxime, ceftriaxone, or augmentin

Question 29

Children ≥ 4 years old OM tx?

Answer 29

S. aureus: Vancomycin, clindamycin, cefazolin

Question 30

When is definitive therapy used?

Answer 30

* Should be delayed until bone cultures can be obtained (surgical debridement, chronic OM) * Discontinue antibiotics for at least two weeks prior to debridement * Antibiotic therapy should be tailored to culture and susceptibility data when available.

Question 31

Staph MSSA Tx?

Answer 31

Nafacillin, oxacillin, cefazolin: Q4-8H (inpatient) Ceftriaxone: QD (outpatient)

Question 32

Staph MSRA OM tx?

Answer 32

Vancomycin Alt: Daptomycin * Hold statin, check baseline CPK -> rhabdomylysis

Question 33

Strep-pen sensitive OM?

Answer 33

Penicillin G and Ampicillin: 6 divided doses) Ceftriaxone: high dose -> not as strong

Question 34

E. coli OM tx?

Answer 34

Ceftriaxone

Question 35

Pseudomonas OM tx?

Answer 35

1. Ceftazidime 2. Cefepime 3. Meropenem 4. Ciprofloxacin/Levofloxacin

Question 36

Duration of OM therapy in adults?

Answer 36

4-6 weeks

Question 37

Duration of MRSA OM?

Answer 37

8 weeks

Question 38

Duration of therapy GNB OM?

Answer 38

≥8 weeks

Question 39

Duration of OM in children?

Answer 39

min 3 weeks

Question 40

What is OPAT?

Answer 40

IV antibiotics administered at home or infusion clinic

Question 41

Criteria for at-home admin of IV ABX?

Answer 41

1. Patients receiving stable treatment 1. Interested/motivated to receive treatment at home 1. Good venous access 1. Support from family or caregivers 1. Safe, stable housing situation, including refrigerated drug storage capability

Question 42

Exclusion criteria for at-home administration of IV antibiotics

Answer 42

1. Vision or dexterity 2. Recent IV drug use

Question 43

What do you need to monitor dialy in OM/

Answer 43

1. Inflammation 2. Fever 3. Redness 4. Tenderness 5. WBC

Question 44

What do you need to monitor Weekly in OM?

Answer 44

1. WBC and CRP: Reduction of inflammatory markers 2. MRI to rule out abscess 3. Vanc levels are collected aat least weekly after stabilization

Question 45

Describe follow up of OM?

Answer 45

1. Follow up cultures not typically indicated 2. Suppressive therapy: * Patients who fail surgery + antibiotics or chronic Osteomyelitis -> long-term oral suppressive therapy, month * Recurrent with prosthetic -> life long

Question 46

Suppression OM of methicillin susceptible?

Answer 46

1. Cefadroxil 2. Cephalexin 3. Dicloxacillin 4. FLucloxacillin

Question 47

Suppression OM of MRSA?

Answer 47

1. BActrim 2. Doxycycline 3. Minocycline 4. Clindamycin

Question 48

Suppression OM of G-?

Answer 48

1. Bactrim 2. Ciprofloxacin 3. Levofloxacin

Question 49

Suppression OM of penicillin sensitive strep and entero?

Answer 49

1. Amoxicillin 2. Penicillin VK

Question 50

Suppression OM of Cutibacterium?

Answer 50

1. Amoxicillin 2. Penicillin VK

Question 51

Who are more susceptible to joint infections?

Answer 51

Children and oldre adults

Question 52

Types of septic arthritis?

Answer 52

**Acquired via adjacent bone infection, or trauma/surgery:** monoarticular **Hematogenous via blood:** 2 or more joints

Question 53

What are the different causes of septic arthritis?

Answer 53

**Native:** S. aureus, strep; E. coli * Pseudomonas If IV drug user or nosocomial * N. gonorrhea from GUT **Prosthetic:** S. aureus, strep, enterococcus, GNRs

Question 54

What is the septic arthritis triad?

Answer 54

1. Dermatitis 2. Tenosynovitis 3. Migratorily polyarthralgia(comes and go)

Question 55

Tx of spetic arthritis?

Answer 55

**Source:** * Joint drainage * Remove prosthesis * Empiric antibiotics cover * Tailoring ABX **Joint rest:** * Avoid weight-bearing initially * Passive ROM exercises

Question 56

IA empiric therapy?

Answer 56

MRSA + ceftriaxone 2 gram IV Q12

Question 57

IV drug user IA tx?

Answer 57

MRSA + pseudomonas

Question 58

PCN allergy IA tx?

Answer 58

MRSA + Aztreonam or cephalosporin

Question 59

N. gonorrhea tx of IA?

Answer 59

Ceftriaxone

Question 60

IA from bite wound tx?

Answer 60

Ampicillin/Sulbactam 3 g IV Q6 **Or** Clindamycin 600 mg IV Q8 + Cipro 400 mg IV Q12 if PCN allergy

Question 61

Hardware retention in prosthetic joint IA tx?

Answer 61

If staph isolated, add rifampin 600 (breaking down the slime layer produce by s.ar)mg po Q24

Question 62

How long is IA duration of therapy?

Answer 62

4-6 weeks IV therapy If prosthesis retained, most patients will require at least 3 months of oral abx +/- rifampin