Lecture 27 Bone and Joint infections Flashcards
What is osteomyelitis, how does infection occur, and what are risk factors?
infection of the bone, may be acute or chronic
up to 24% of patients with it also have diabetic foot ulcers
progressive destruction of the bone and formation of sequestra
Mechanism: hematogenous seeding (more common in children), contiguous spread from adjacent tissues and joints, direct inoculation of microorganisms into bone as result of trauma or surgery
Risk Fx: circulatory diseases - DM, PVD,, open fracture or surgery, chronic soft tissue infection, immunocompromised, IV drug or catheter use, pressure ulcers
How does osteomyelitis present in patients?
Acute: typically in 2 weeks of initial infection, more common in children
systemic S&S - fever, lethargy, irritability
Local S&S - acute onset pain/tenderness at site, erythema, swelling, delayed wound healing
Chronic: months or years after initial infection, more common in adults
S&S - low grade fever, chronic pain, delayed wound healing, persistent sinus tract or wound drainage, soft tissue damage, exposed bone, bone instability
if pt has generalized vascular insufficiency may also have perforating foot ulcer, may be painless (if peripheral neuropathy)
What are the most common pathogens when it comes to osteomyelitis?
> 50% of cases: S. aureus (MRSA may account for more than 1/3 of staphylococcal isolates), CoNS
<25% of cases: Streptococcus, enterococcus, enterobacterales, pseudomonas, anaerobes, M. tuberculosis
<5% of cases: Mycobacterium avium complex, mycoplasma, fungi, brucella, salmonella
What is the general management strategy when it comes to osteomyelitis?
most cases in adults require combo of antibacterial and surgical tx
when possible antimicrobial tx should be withheld until percutaneous aspirate or deep surgical cultures have been obtained
duration of tx depends on results of surgery
What is empiric therapy regarding hematogenous long bone osteomyelitis treatment, what pathogens are involved, duration?
Pathogens: MSSA/MRSA, Rare - streptococcus, enterobacterales, M. tuberculosis, fungi
Tx: Cloxacillin 2 g IV Q4H OR Cefazolin 2 g IV Q8H
if allergy to penicillin and cefazolin OR MRSA is suspected ⇒ Vancomycin (target trough 10-20 mg/L)
consider MRSA if preceding trauma, multifocal lesions, disease in adjacent muscle
surgical management - debridement, drainage recommended
Duration: 4-6 weeks - recommended minimum 2 weeks with IV then switch to PO agents with good bioavailability and bone penetration may be considered with clinical improvement ⇒ if MRSA - minimum 8 weeks
What is empiric therapy regarding contiguous/vascular insufficiency/diabetic foot osteomyelitis cases, what pathogens are involved, duration?
Pathogens: MSSA/MRSA, streptococcus, enterococcus, enterobacterales, P. aeruginosa, anaerobes, Candida (often polymicrobial)
Mild-Moderate: amox/clav 875 mg PO TID OR (Cefazolin 2 g IV Q8H +/- Metronidazole 500 mg PO BID ⇒ this regimen doesn’t cover enterococcus or pseudomonas), if MRSA suspected ⇒ add TMP/SMX 2 DS tabs PO BID OR doxycycline 100 mg PO BID, consider MRSA id previous MRSA infection (last year), recent antibacterial use or hospitalization, anaerobic coverage if severe ischemia, foul-smelling, necrosis, gangrene
Moderate-Severe: (Vancomycin target 10-20 mg/L + Ceftriaxone 1-2 g IV QD + Metronidazole 500 mg Q12H) OR amox/clav 1.2 g IV Q8H
Severe/Life Threatening: (Piperacillin-tazobactam 3.375 g (or 4.5 g) IV OR meropenem 500 mg IV Q6H) + Vancomycin target 10-20 mg/L
Duration: >/= 6 weeks, switch to PO should be guided by clinical improvement and deep tissue C&S
What is empiric therapy regarding vertebral (spinal OM, spondylodiscitis, septic discitis, disc space infection) osteomyelitis, what pathogens are involved, duration?
Pathogens: MSSA/MRSA, Rare - streptococcus, enterococcus, enterobacterales, P. aeruginosa, M. tuberculosis, brucella, fungi,, if spinal implant also CoNS, C. acnes
Tx: Vancomycin target 10-20 mg/L + Ceftriaxone 1-2 g IV QD
if blood culture has Gram + cocci in clusters ⇒ Vancomycin target 10-20 mg/L + Cefazolin 2 g IV Q8H
Duration: 6 weeks, prolonged tx if abscesses cannot be drained or if spinal implant, MRSA, and/or end-stage renal disease, often need lifelong suppression with implants
What are prosthetic joint infections (PJI), and risk factors?
infection of this, may involve joint space, adjacent bone or periprosthetic tissue
most commonly affects total knee or hip arthroplasty
estimated 1-2% incidence of pt receiving these procedures
Risk Factors: Pt - previous revision arthroplasty, previous this at same site, smoking, obesity, DM, RA, malignancy, immunosuppression
Surgery - operative time > 2.5 hours, simultaneous bilateral arthroplasty, allogeneic blood transfusion
Postoperative - wound healing complications, CV complications (ex. Afib, MI), UTI, prolonged hospital stay, S. aureus bacteremia
What is the clinical presentation of PJIs?
Acute: local inflammation, pain, systemic sx (ex. fever, chills)
Chronic: sx persistence for several weeks, less local inflammation compared with acute, chronic joint effusion, pain, sinus tracts
What is involved in diagnosis of PJIs?
has to have at least one of: sinus tract communicating with prosthesis or visualization of prosthesis OR isolation of same organism from >/= 2 cultures or from 1 culture if virulent organism (ex. S. aureus, GAS, aerobic GNB) OR gross purulence in joint space (leukocyte count >3000 cells/microlitre with >80% PMNs) OR acute inflammation or visible organisms on histological exam
diagnostic arthrocentesis should be done unless surgery imminent and antimicrobials can be withheld before surgery
antimicrobial tx should be d/c >/= 2 weeks prior to surgery
Cultures: blood if febrile or acute sx onset, periprosthetic tissue cultures x 5-6 samples
What are the usual pathogens involved in PJIs?
Early (<3 months) after implant: S. aureus (MOST COMMON), CoNS, enterobacterales, polymicrobial
Delayed (3-24 months): CoNS, Cutibacterium, anaerobes, S. aureus, streptococcus
Late/Hematogenous (>2 years): streptococcus, enterococcus, staphylococcus, enterobacterales, P. aeruginosa, others
What is the surgical options for tx of PJIs?
Debridement + replacement of linear and implant retention (DAIR): follow by prolonged antibacterials,, consider if infection within 30 days or acute hematogenous with sx lasting <3 weeks with stable prosthesis, bone/tissue in good condition, no sinus tract, known susceptible organism
One-Stage Exchange: removal of prosthesis, debridement, replacement of prosthesis all in single procedure followed by prolonged antibacterials
option in pt with adequate remaining bone stock, good condition of tissue, no severe comorbidities, absence of difficult to treat organism
Two-Stage Exchange: removal of infected prosthesis, debridement, placement of temporary antibacterial-impregnated cement spacer, admin of systemic antibacterials, then placement of new prothesis 6-12 weeks later
option for pt medically able to undergo multiple surgeries
Removal of Prosthesis without replacement: considered in pt with serious comorbidities where repeat surgery not option
Long-term suppressive antimicrobial tx: when not suitable for surgery
What is empiric therapy for PJIs, and duration of therapy?
Empiric: Vancomycin target 10-20 mg/L + Ceftriaxone 1-2 g IV QD
Long-term/lifelong suppressive tx: Vancomycin + Ceftriaxone as above F4-6W then ⇒ TMP/SMX 1 DS tab po BID OR doxycycline 100 mg PO BID OR minocycline 100 mg PO BID
Duration: if Debridement and retention (DAIR) ⇒ IV/PO for total 3 months (except knee ⇒ 6 months)
if one-stage exchange ⇒ IV/PO for total 3 months (all joints)
if two-stage exchange ⇒ 4-6 weeks IV/PO + >/= 2 weeks antibacterial free interval before re-implantation, follow this continued until intraoperative cultures come back negative or for 6-12 weeks if positive intraoperative cultures
if removal of prosthesis without replacement ⇒ 4-6 weeks of systemic antibacterial tx
What is septic arthritis, risk factors?
infection of one or more joints causing acute arthritis, may be with or without swelling, most commonly monoarticular but may be oligoarticular
may be due to hematogenous or contiguous spread or direct inoculation
mortality ranges from 7-15% to 30-50% if pt has significant comorbidities or multiple joints involved
Risk Factors: Major - RA, advanced age, DM, chronic renal failure, previous joint surgery, penetrating joint injury, injection drug use, endocarditis, immunosuppression, organ/bone marrow transplant
Minor - gout/pseudogout, OA, Charcot’s arthropathy, malignancy, chronic liver disease, alcoholism, intra-articular injections, skin disease (with or without infection), low socioeconomic status
What are the pathogens usually involved in septic arthritis?
usually monomicrobial, polymicrobial may happen if penetrating injury, contiguous spread, etc
Pathogens: S. aureus (MOST COMMON, 37-65%), streptococcus, H. influenzae, CoNS, E. coli, N. gonorrhoeae, P. aeruginosa
What are clinical presentations of septic arthritis?
suspect in any pt with acute onset of hot, red, tender, swollen joint with restricted movement ⇒ medical emergency prompt diagnosis very important
Classic definition requires any of: clinical signs of infected joint and pathogenic organism isolated in synovial fluid, pathogenic organism isolated in blood or other site and signs of infected joint, signs of infected joint and turbid synovial fluid in pt with recent antibacterial tx, histologic or radiologic findings consistent with SA
What is empiric therapy for septic arthritis?
Empiric: Cefazolin 2 g IV Q8H OR Cloxacillin 2 g IV Q4H, both for 2-4 weeks
MRSA/IDU/Immunocompromised/Penetrating Trauma: (Vancomycin target 10-20 mg/L + Ceftriaxone 1-2 g IV QD) for 2-4 weeks, consider MRSA if preceding trauma, multifocal lesion, disease in adjacent muscle
*if pt has injection drug use with sternoclavicular/sacroiliac joint infection consider P. aeruginosa and use Vancomycin + ciprofloxacin 750 mg PO BID (or 400 mg IV Q8H)
