iPTX3 EX3 L10 (BONE AND JOINT) (RICHARDSON)

Acute OM is defined as infection lasting...

Less than 6 weeks

No bone necrosis (yet)

Chronic OM is defined as an infection lasting...

Greater than 6 weeks

Bone necrosis present

Describe hematogenous OM

Vertebral OM

Pelvic OM

Clavicular OM

Describe contiguous OM

Trauma

Surgery

Extension of SSTI

Describe vascular insufficiency

Diabetic Foot Infections (DFI)

Risk factors for OM (nine)

1. Bacteremia (especially with hardware)

2. IVDU

3. HD

4. Long-term catheters

5. Compound fractures

6. Recent surgery

7. Poor circulation

8. Chronic soft tissue infection/poor healing wounds

9. Diabetic foot infections, decubitus ulcers, burns

OM infection is initiated when there is one or more of the following... (three)

1. High inoculum of bacteria

2. Trauma

3. Foreign bodies

T/F: Hematogenous OM (20%) is often polymicrobial.

False; often monomicrobial.

T/F: Contiguous OM and diabetic foot infections are typically *polymicrobial*.

True

How does bone necrosis occur in OM?

Bacterial growth in bones -> pus formation and pressure buildup -> segmental bone necrosis and new bone formation (involucrum)

Most common causative organism of OM?

Staph aureus

Symptom presentation of OM?

Localized pain, tenderness, warmth, erythema, swelling

Non-specific

*But we grab CRP levels and ESR to affirm presence of inflammation*

Gold standard of OM diagnosis?

MRI

Bone biopsy - QUINTESSENTIAL

He wants everyone to know this

Imaging we can collect to help OM diagnosis? (three)

1. MRI - Gold standard

2. CT

3. X-ray

T/F: Swabs of superficial wounds, sinus tracts cultures, aspiration of material adjacent to the periosteum can be used to diagnose OM.

False; not diagnostic of OM.

T/F: Osteomyelitis often requires surgical debridement of necrotic tissue.

True

Suspect vertebral OM in patients with...

Recent S. aureus bacteremia

Empiric OM regimen? (S. aureus suspected) (two agents)

1. Cefazolin

OR

2. Vanco

Why do we not use aminoglycosides for OM?

Bone penetration bad

Minimum duration for OM treatment?

6 weeks

Recommended duration of therapy for patients with high risk of vertebral OM recurrence?

8 weeks or more

Describe septic arthritis

Inflammation in a joint secondary to infection of synovial or periarticular tissue

T/F: N. gonorrhoeae is the most common cause of septic arthritis in the US.

True

Common non-gonococcal organisms causing septic arthritis? (four)

More common:

1. S. aureus

2. Strep spp.

Less common:

3. P. aeruginosa

4. E. coli

Risk factors for non-gonococcal septic arthritis? (nine)

1. Age >60 y/o

2. Diabetes

3. Corticosteroid therapy

4. Immunosuppression

5. RA

6. Degenerative joint disease

7. Recent joint surgery

8. Intra-articular corticosteroid injection

9. IV drug abuse

Risk factors for gonococcal septic arthritis? (eight)

1. Female gender (asymptomatic nature)

2. Menstruation

3. Pregnancy

4. Male homosexuality

5. Urban residence

6. Promiscuity

7. Low socioeconomic status

8. Piliated N. gonorrhoeae strains w/ phase variation

How does non-gonococcal septic arthritis typically present? (systemic and local symptoms)

Systemic:

Fever

Malaise

Local:

Pain

Warmth

Swelling

Decreased ROM

Most common joints affected by non-gonococcal septic arthritis? (four)

Primary

1. Knee

2. Hip

Secondary

3. Shoulder

4. Ankle

KNOW FOR EXAM

Duration of therapy for H. influenzae or Streptococcus spp. septic arthritis?

2 weeks

Duration of therapy for S. aureus or gram-negative bacilli septic arthritis?

3 weeks

MRSA septic arthritis regimen?

Vanco

Linezolid

Alternative:

TMP-SMX or minocycline +/- rifampin

MR-CoNS septic arthritis regimen?

Vanco

Linezolid

Alternative:

TMP-SMX or minocycline +/- rifampin, clinda

MSSA/MS-CoNS septic arthritis regimen?

Nafcillin or clindamycin

Alternative:

Cefazolin or vancomycin

GAS/GBS septic arthritis regimen?

Penicillin or ampicillin

Alternative:

Clindamycin or cefazolin

Enterococcus spp. septic arthritis regimen?

Ampicillin

Alternative:

Unasyn or linezolid

Clinical presentation of gonococcal SA?

Skin lesions (small erythematous papules)

Typically asymptomatic though

5-10 lesions when papules present on affected joint

How do we diagnose gonococcal SA?

Isolation from joint fluid

Endocervix cultures

Duration of treatment for gonococcal SA?

Starts after 48 hours of clinical resolution?

7-10 days

Initial therapy for gonococcal SA?

Ceftriaxone 1g IV/IM Q24H

- May transition to PCN or tetracycline if isolate susceptible

Alternative therapy for gonococcal SA?

Cefotaxime 1gm IV Q8H

Most common joints affected by prosthetic joint infection (PJI)? (two)

1. Knee

2. Hip

T/F: Antimicrobial therapy is sufficient in treatment of PJI.

False; surgical debridement (source control) required.

Early onset PJI is defined as occurring...

Occurring

Delayed-onset PJI is defined as occurring...

Between 3 and 12 months after implantation

Symptoms associated with delayed-onset PJI?

Chronic pain or loosening prosthesis

Symptoms associated with late onset PJI?

Acute and septic arthritis syndrome

Pathogens to worry about in PJI? (five)

Staph (MR, MS, CoNS)

Enterococcus (VRE, VRS)

P. aeruginosa

Enterobacterales

GAS/GBS strep

T/F: Antimicrobial therapy for treatment of PJI should be withheld 2 weeks prior to culture when possible.

True, we wanna really know what bacteria are in there.

Diagnostic criteria for PJI? (three)

1. 2+ cultures or preop aspiration + intraoperative culture growing same organism

2. Purulence surrounding prosthesis without another known etiology

3. Growth of a virulent organism (i.e. S. aureus)

Why do we use rifampin for Staph PJI?

Biofilm

T/F: Rifampin discolors bodily fluids orange.

True

He said to know this