Bone/Joint Infections

Question 1

Bone/Joint Infections

Answer 1

• Osteomyelitis
• Infectious (septic) arthritis
• Prosthetic joint infections

Question 2

Osteomyelitis

Answer 2

• Inflammation of the bone
• Can remain localized or spread throughout bone
• Classified by route and duration of infection

Question 3

Osteomyelitis Routes of Infection

Answer 3

• Hematogenous osteomyelitis - 19%
• Contiguous osteomyelitis - 47%
• Peripheral vascular insufficiency - 34%

Question 4

Osteomyelitis Duration of Infection

Answer 4

• Acute (56%) - recent onset, days to 1 week

- Chronic (44%) - symptoms >1 mo before therapy or relapse of an initial infection

Question 5

Hematogenous + <1 yr

Answer 5

• Site: Long bones and joint

- Risk factors: prematurity, umbilical catheter, RDS, asphyxia

Question 6

Hematogenous + 1-20 yrs

Answer 6

• Sites: long bones (femur, tibia, humerus)

- Risk factors: Infection (URI, cellulitis, respiratory), trauma, sickle cell

Question 7

Heamtogenous + > 50 yrs

Answer 7

• Site: Vertebrae

- Risk factors: DM, trauma to spine, UTI

Question 8

Hematogenous + All ages

Answer 8

• Site: vertebrae > 50%

- Risk factors: IDU

Question 9

Contiguous Osteomyelitis

Answer 9

• Typically >50 y.o.
• Sites: femur, tibia, mandibule
• Risk factors: Hip fractures, open fractures

Question 10

Vascular Insufficiency

Answer 10

• Typically > 50 y.o.
• Sites: feet, toes
• Risk factors: DM, PVD, pressure sores

Question 11

Hemagenous Bacteriology

Answer 11

• Children: S. aureus
• Neonates: S. aureus, Group B Strept., E. coli
• Vertebral: S. aureus, E. coli, MTB
• IDU: Gram-neg 88% of the time

Question 12

Contiguous Bacteriology

Answer 12

• S. aureus
• P. aeruginosa, strept., E. coli, staph. epidermidis
• Anaerobes

Question 13

Vascular Insufficiency Bacteriology

Answer 13

• Mixed-flora: staph. and strept. or the combo of staph + strept + enterobacteriaceae
• Enterococci and anaerobes can also be involved

Question 14

Anaerobe Involvement

Answer 14

• B. fragilis is most common
• Predisposing factors: vascular disease, peripheral neuropathy, bites, trauma
• Foul smelling

Question 15

Osteomyelitis Clinical Presentation

Answer 15

• Hematogenous: tenderness of the infected area, pain, swelling, fever, chills, decreased motion, malaise
• Contiguous: localized tenderness, warmth, edema, erythema of the infected site
• Vascular Insufficiency: localized pain, swelling, redness, ulceration, drainage

Question 16

Osteo. Diagnosis

Answer 16

• Patient history
• WBCs
• ESR
• Anatomic images: radiographs, MRI, CT
• Functional images: nuclear
• Microbiologic Dx: bone biopsy/aspiration, blood bultures

Question 17

Osteo Newborn Treatment

Answer 17

• Up to 4 mo.
• Nafcillin: 50-75 mg/kg/day IV + Cefotaxime 100 mh/kg/day IV
• Vanco 40 mg/kg/d IV + cefotaxime 100 mg/kg/day IV

Question 18

Osteo Children < 5 y.o. Treatment

Answer 18

• If vaccinated for H. influenzae: Nafcillin: 100 mg/kg/day IV OR Cefotaxime 100 mh/kg/day IV
• Not vaccinated: Cefuroxime 150 mg/kg/day IV

Question 19

Osteo Children >5 y.o. Treatment

Answer 19

-Nafcillin: 100 mg/kg/day IV OR Cefotaxime 100 mh/kg/day IV

Question 20

General Osteo Children Treatment

Answer 20

• If allergic to PCN or MRSA: Vanco 40 mg/kg/day IV OR Clinda 40 mg/kg/d IV
• Tx for 4-6 weeks
• Start IV and switch to PO when etiology known

Question 21

Hematogenous Adults + MSSA Confirmed Treatment

Answer 21

• Nafcillin 2g IV q4h
• Cefazolin 2g IV q8h
• Vanco 1g IV q12h (best empiric choice)
• Tx for 6-8 weeks

Question 22

Hematogenous Adults + IDU Treatment

Answer 22

• Nafcillin 2g IV q4h + Cipro 400 mg IV q12h
• Vanco 1g IV q12h + Cipro 400 mg IV q12h (best empiric choice)
• Tx for 6-8 weeks

Question 23

Contiguous w/o Vascular Insufficiency + Adult Treatment

Answer 23

• Postop or trauma
• Nafcillin 2g IV q4h + Cipro 400 mg IV q12h OR Cefepime 2g IV q12h
• Zosyn 3.375 IV q6h
• Vanco 1g q12h + Cipro 400 mg q12h OR Cefepime 2g IV q12h (best empiric choice)
• Tx for 6-8 weeks

Question 24

Contiguous w/ Vascular Insufficiency + Adult Treatment

Answer 24

• Zosyn 3.375g IV q6h
• Cefepime 2g q8h + Metronidazole 500 IV q6h
• Cipro 400 mg IV q12h OR Aztreonam 2g IV q8h + Metronidazole 500 IV q6h
• Add Vanco 1g IV q12h to cover MRSA
• Tx for 6-8 weeks

Question 25

Other Modalities

Answer 25

• Staph infection with foreign materials: Add rifampin 600-900 mg PO QD or divided q8-12h
• Aminoglycoside impregnated beads: beads can be strung on wire and packed in bone to stay for ~2 weeks, slow release
• Hyperbaric oxygen therapy: associated with increased vascularity and enhancement of bone/soft tissue healing
• Surgical intervention: debridement

Question 26

Controversies: Oral antibiotics

Answer 26

• Confirmed osteomyelitis
• Known culture and sensitivity
• Suitable oral agent available
• Compliance assured
• Suitable candidates: children with good IV repsonse and adults w/o DM or PVD

Question 27

Controversies: [Bone]

Answer 27

• Can be detected soon after administration
• Semisynthetic PCN, cephalosporins, clinda, AMGs
• Very good penetration: quinolones

Question 28

Osteo Monitoring Parameters

Answer 28

• Culture: at initiation of therapy
• Complete cure = no relapse for 1 yr
• WBC: 1-2x/week until WNL
• ESR: weekly, may not normalize until several weeks
• Clinical signs/symptoms: daily