Bone and Joint infections

Question 1

Key Concept #2 - culture and susceptibility information

Answer 1

Osteomyelitis - Bone sample/biopsy, via surigal intervention

Septic arthritis and Prosthetic joint infection - joint aspiration with examination of synovial fluid to establish diagnosis and/ or surgical intervention

blood cultures important
- staphy aureus most common

Question 1

Key concept #1 - Types of bone and joint infections

Answer 1

Osteomyelitis - infection of the bone causing inflammation of the bone marrow and surrounding bone

Septic arthritis - inflammatory reaction within the joint tissue and fluid due to a microorganism

Prosthetic joint infection - infection of a prosthetic join and joint fluid

Question 2

Key Concept #3- antibiotic therapy is more intense

Answer 2

Usually requires antibiotic therapy given for longer durations and higher doses compared to other types of infection

Osteomyelitis - 4-8 weeks

Septic arthritis - 2-4 weeks

Prosthetic joint infection - 6-12+ weeks

Question 3

Key concept #4 - patient centered care is important

Answer 3

always consider
- will the patient need long term IV access for antibiotic therapy?
If IV antibiotic therapy is selected where will the patient receive it?
if oral antibiotic selected will the aptient be adherent
Dose patients insurance cover medication

Question 4

Key concept #5 - think outside the box

Answer 4

may patients experience barriers to appropriate antibiotic therapy due to the intensity of treatment for bone and joint infections

Question 5

Osteomyelitis Pathogensis

Answer 5

Develops in 3 main ways
1.Hematogenous spread
- microbe reaches bone via bloodstream
- in children involves growing long bones
- in adults involved vertebrae osteomylitis

2. Contiguous spread
   - Microbe reaches bone from soft tissue infection or direct inoculation
   - commonly polymicrobial
3. Vascular insufficiency
   - Microbe reaches bone from soft tissue infection
   - risk factors - DM, Peripheral vascular disease, commonly polymicrobial

Question 6

Osteomyelitis presentation and diagnosis

Answer 6

signs and symptoms
- acute symptoms: fever, localized pain/tenderness/swelling, decreased range of motion
- Chronic symptoms - pain, drainage/sinus tract, decreased range of motion

Diagnostic considerations
Lab findings - Elevated WBC count, ESR, CRP
Radiologic findings- X-ray - soft tissue swelling, periosteal thickening, bone destruction, MRI is standard of care

Question 7

Osteomyelitis - Treatmeant approach

Answer 7

surgical intervention and antibiotic therapy
Can hold on starting antibiotic therapy until culture returns for patients clinically stable

Question 8

Treatment for all 3

Answer 8

Empiric options
Cefazolin 2gm IV Q8H*
Ceftriaxone 2g IV Q24H*
Cefepime 1-2g IV Q8H*
Zosyn 3.375-4.5 g IV Q6-8H
Ampicillin/sulbactam 3 g IV Q6H
Meropenem 1-2 g IV Q8H
Ciprofloxacin 400mg IV Q8-12H*
Levofloxacin 750mg IV/po Q24H*

+
MRSA coverage
Vancomycin
Daptomycin 6-12mg/kg IV Q24H
Linezolid 600mg IV/PO Q12H

• = if anaerobic coverage desired, metronidazole 500mg IV/PO Q8-12H should be added

Question 9

Osteomyelitis treatment duration specific considerations for diabetic foot infection related to osteomyelitits or vertebral osteomyelitits due to MRSA

Answer 9

diabetic foot infection related to osteomyelitits
- complete amputation of infected bone/tissue = 2-5 days
- resection of all osteomyelitits, soft tissue infection remains = 1-2 weeks
- resection performed, osteomyelitis reamins = 3 weeks

vertebral osteomyelitits due to MRSA
- 8 weeks

Question 10

Osteomyelitis Oral antibiotic options

Answer 10

streptococci - amoxicillin, cephalexin, clindamycin
MSSA - dicloxacillin, cephalexin, cefadroxil TMP/SMX, Linezolid
MRSA - linezolid, TMP/SMX, clindamycin
GNRs - TMP/SMX, fluoroquinolones

Daptomycin 2 dose stratagey IV on day 1 and 8 privdes 6-8 weeks of coverage

Question 11

Septic arthritis pathogenesis and risk factors

Answer 11

1. Hematogenous
2. direct inoculation
3. contiguous

Risk factors
joint disease, advanced age, chronic disease, sexually transmitted infection, immunosuppression, trauma, prosthetic joints, IV drug use, Endocarditis

Question 12

Septic Arthritis common pathogens

Answer 12

Staph aureus

in sexually active adults - neisseria gonorrhoeae

Question 13

Septic Arthritis presentation and diagnosis

Answer 13

signs and symptoms
joint pain, decreased range of motion, swelling, erythema, warmth, fever, chills
Monoarticular in the majority of cases

Diagnostic considerations
Labs - increased WBC, ESR, CRP
Arthrocentesis - purulent, low viscosity synovial fluid
PNM count >50,000
Gram stain and culture

Radiologic - X-ray, CT, MRI

Question 14

Septic arthritis Approach to treatment

Answer 14

Proceed with pathogen directed treatment once culture and susceptibilities are known
- IV or high bioavailable oral is accepted

treatment duration
s aureus, GNR - 4 weeks
Streptococci - 2 weeks
N. Gonorrhoeae - 7-10 days

Question 15

Prosthetic join infection pathogenesis

Answer 15

1. Hematogenous
2. direct inoculation
3. contiguous

involves development of biofilm

Question 16

Prosthetic join infection common pathogens

Answer 16

S aureus

Question 17

Prothetic joint infection - presentation and diagnosis

Answer 17

Signs and symptoms of prosthetic joint infection
joint pain, decreased range of motion, swelling, erthema, warmth, fever, chills, sinus tract or persistent wound drainage over joint prosthesis, loosening of prosthesis, important to review history of prosthesis

Lab - Increased WBC, ESR, CRP
Arthrocentesis - cell count/differential, gram stain, and culture
Radiologic finding - X-ray

Question 18

Prosthetic joint infection approach to treatment

Answer 18

Surgical intervention and antibiotic therapy

Surgical intervention
1. Debridement and retention of prosthesis
2. 1 stage exchange - take out infected join and put new one in and close it up - negative is that the infection is stilll in the body and can get onto new prosthetic
3. 2 stage exhange - Take joint out and put spacer in for 6 weeks which is hard to walk on and uncomfy then another surgery to remove the space and add new joint (bonus is that infection is gone and no way new joint can get infected)

Rifampin added to treatemnt for retention of prosthesis or 1 stage exhange
- Rifampin 300-450mg PO BID

Question 19

Debridement and retention of prosthesis- prosthetic joint infection tx

Answer 19

pathogen directed treatment + rifampin x 2-6 weeks

oral antibiotic treatment + rifampin x3 months (hip) - 6 months (knee/joint0

May consider long term antibiotic supression after completion of treatment

Question 20

1-stage exchange- prosthetic joint infection tx

Answer 20

Pathogen directed treatment + rifampin x 2-6 weeks

oral antibiotic treatment + rifampin x 3 months (oral agents same as osteomyelitis)

Question 21

2-stage exchange- prosthetic joint infection tx

Answer 21

Pathogen directed treatment x 4-6 weeks

Question 22

Amputation with complete removal of infected bone/hardware - prosthetic joint infection tx

Answer 22

Pathogen directed treatment x24-48 hours

Question 23

▪JB is a 67-year-old male presenting to the hospital with a 3-week onset of back pain
with worsening severity and periodic fevers.
▪Past medical history
▪HTN
▪Afib
▪T2DM

▪Home medications
▪Lisinopril 40 mg PO once daily
▪Pantoprazole 40 mg PO once daily
▪Metformin 1000 mg PO BID
▪Apixaban 5 mg PO BID
40

▪MRI of the spine is performed
⎻ L2-L3 vertebral osteomyelitis

▪Laboratory findings
⎻ WBC: 16,000 cells/mL
⎻ CRP: 35 mg/dL

▪Vital signs
⎻ Afebrile
⎻ Hemodynamically stable

Antibiotics are held and interventional radiology is consulted for biopsy

▪Biopsy is performed and antibiotic treatment is being initiated

Which of the following would be an
acceptable empiric regimen?

A. Cefepime 1 g IV Q8H and ciprofloxacin 400mg IV Q12H
B. Ceftriaxone 2 g IV Q24H and vancomycin (dose based on PK eval)
C. Linezolid 600mg Q12H and amoxicillin 1000 mg PO Q8H
D. Meropenem 1 g IV Q8H

Answer 23

Hold antibiotic till biopsy come back then start B

Question 24

JB is a 67-year-old male presenting to the hospital with a 3-week onset of back pain with worsening severity and periodic fevers. ▪Biopsy cultures result with MRSA ▪The ID physician recommends patient complete 8 weeks of IV antibiotic treatment ▪Patient preferences ▪Lives alone, unable to self-administer IV antibiotic at home ▪Only able to come to infusion center once per day ▪Insurance coverage not available for high-cost drugs Which of the following would be an acceptable pathogen-directed regimen? A.Vancomycin 1 g IV Q12H B. Daptomycin 8-12mg/kg/ IV Q24H C. Recommend discontinuation of antibiotic treatment D. Ceftaroline 1800mg IV Q24H (continuous Infusion)

Answer 24

B

Question 25

JB is a 32-year-old male presenting to the hospital with a 3-week onset of right knee pain, swelling, and erythema. He also reports daily fever and general malaise. ▪Past medical history ▪Active IV drug use ▪Home medications ▪None ▪CT of the right knee is performed ▪Findings concerning for septic arthritis 43 ▪Laboratory findings ⎻ WBC: 25,000 cells/mL ⎻ CRP: 43 mg/dL ▪Vital signs ⎻ Febrile (102 F) ⎻ Hemodynamically stable ▪Arthrocentesis is performed ▪PMN count: 77,000 cells/mm3 ▪Low synovial glucose (35 mg/dL) ▪Elevated synovial protein (4.8 g/dL) ▪Blood cultures obtained Is the arthrocentesis result consistent with septic arthritis? A. Yes B. No C. Im tired

Answer 25

A

Question 26

JB is a 32-year-old male presenting to the hospital with a 3-week onset of right knee pain, swelling, and erythema. He also reports daily fever and general malaise. ▪Synovial fluid culture results with MSSA ▪Blood culture results with MSSA ▪Transesophageal echocardiogram (TEE) does not show endocarditis ▪The ID physician recommends 6 weeks of IV antibiotic treatment Patient preferences – provider unwilling to allow patient to discharge with central line without constant observation ▪Patient unwilling to go to a facility for IV antibiotic treatment ▪Patient’s insurance will cover all options CANT PUT A CENTRAL LINE IN PATIENT Which of the following would be an acceptable pathogen-directed regimen? A. Vancomycin 1.5 g IV Q12H B. Daptomycin 6-12 mg/kg IV Q24H C. Amoxicillin 1000mg PO TID D. Dalbavancin 1500mg IV on day 1 and day 8

Answer 26

D

Question 27

JB is a 73-year-old male presenting to the hospital with a 2-week onset of right foot pain, swelling, erythema, and purulent drainage. Patient has deep wound on right heel ▪Past medical history ▪T2DM ▪HTN ▪Home medications ▪Metformin 1000 mg PO BID ▪Semaglutide 2 mg SC once weekly ▪Insulin degludec 20 units SC once daily ▪Lisinopril 20 mg PO once daily 47 ▪X-ray of the right foot is performed ▪Findings concerning for osteomyelitis of the right calcaneus ▪Laboratory findings ⎻ WBC: 13,000 cells/mL ⎻ CRP: 43 mg/dL ⎻ ESR: 120 mm/hr Podiatry and ID is consulted – both recommend below-knee amputation Which of the following would be an acceptable empiric regimen while the patient is awaiting amputation? A. Ampicillin/Sulbactam 3g IV Q6H B. Piperacillin/tazobactam 3.375 g IV Q6H + vancomycin C. Ceftriaxone 2g IV Q24H + Metronidazole 500mg PO Q12H + Linezolid 600mg PO Q12H D. Meropenem 1 g IV Q8H + Vancomycin

Answer 27

All options are appropriate

Question 28

JB is a 73-year-old male presenting to the hospital with a 2-week onset of right foot pain, swelling, erythema, and purulent drainage. Patient has deep wound on right heel ▪Below-knee amputation is performed What is the appropriate antibiotic duration? A. 2-5 days B. 7-14 days C. 2-4 weeks D. 3 months

Answer 28

A

Question 29

Treatment options of pathogen directed antibiotics MSSA

Answer 29

Nafcillin 2g IV Cefazolin 2g IV

Question 30

Treatment options of pathogen directed antibiotics PCN-suscep Strep

Answer 30

Pencillin G Ceftriaxone

Question 30

Treatment options of pathogen directed antibiotics MRSA

Answer 30

Vanc, Linezolid, dalbavancin Daptomycin

Question 31

Treatment options of pathogen directed antibiotics Enterococci

Answer 31

Pen G, vanc, linzeolid Ampicillin, Daptomycin

Question 32

Treatment options of pathogen directed antibiotics GNR no aeruginosa

Answer 32

Ceftriaxone Ciprofloxacin

Question 33

Treatment options of pathogen directed antibiotics p. aeruginosa

Answer 33

Cefepime, Zosyn Ciprofloxacin

Question 34

Treatment options of pathogen directed antibiotics Polymicrobial

Answer 34

Meropenem, zosyn Ertapenem, Unasyn