Infections of bones, joints, muscles (clinical) - Stillwell Flashcards
1
Q
nuclear medicine bone scan
-any inflammation looks “hot”
A
- intense uptake on early and delayed phases –> think osteomyelitis**
- intense uptake on early and less intense delayed –> think cellulitis**
2
Q
ostoemyelitis
A
- inflammatory process of bone from infection
- organism: Staph aureus most common**
chronic: dead bone, fibrous capsule, inflammatory infiltrates (lymphocytes for chronic, neutrophils for acute), weak bone
3
Q
periostitis
A
- inflammation of periosteum
- may/may not be infectious
- elevated/thickened periosteum**
- shin splints and trauma are cause
4
Q
sequestrum
A
- piece of dead/necrotic bone, most often from infection**
- lead to vascular thrombosis and bone ischemia
- no blood vessels –> antibiotics can’t reach
5
Q
involucrum
A
- layer of new bone growth outside of infected area, surround sequestrum**
- poor, weak bone from periosteum
- in chronic osteomyelitis
6
Q
bone abscess
A
- purulent material in bone/bone marrow cavity under the periosteum**
- Brodies abscess** –> walled off inefection, end of long bone, resembles osteoid osteoma
- Pott’s puffy tumor** –> subperiosteal abscess of frontal bone due to osteomyelitis, sinusitis, cocaine, brain abscess
7
Q
septic arthritis
A
- infected joint space with inflammation
- decreased ROM with synovial effusion**
8
Q
aseptic arthritis
A
- inflammation in joint - may or may not be infectious
- seen in osteoarthritis, autoimmune, gout/pseudogout, or after surgery
9
Q
prosthetic joint infection
A
-infection of artificial joint, hardware, or surrounding bone
10
Q
synovitis
A
-inflammation of synovial fluid/membrane –> fluid build up
11
Q
tenosynovitis
A
- inflamed synovial membranes around tendons (usually flexors)
- fluid filled
- secondary to infection –> Staph. aureus most common**
- also pasteurella, bartonella, eikenella, mycobacteria marinum**
- neisseria gonorrhea from disseminated gonorrhea**
12
Q
septic tendinitis
A
- infection of tendon
- hard to treat –> avascular –> antibiotics cannot enter site
13
Q
myositis
A
- inflammation of muscle tissue
- secondary to infection, overuse, autoimmune, meds, trauma
14
Q
polymyositis
A
- bacterial infection of muscle
- TROPICAL regions***
15
Q
abscess
A
- muscle abscess - pus collection within muscle
- psoas abscess in IV drug users
- vertebral osteomyelitis can enter psoas - interfacial abscess - b/w fascial planes
16
Q
necrotizing fasciitis aka (gangrene, myonecrosis, flesh eating)
A
- polymicrobial –> synergistic
- rapid spread from fascial planes to muscle/soft tissue
- organisms: Clostridium perfringes; staph aureus and strep** producing exotoxins
- gas in the tissues**
- require debridement (antibiotics fail)
17
Q
osteomyelitis - hematogenous spread
A
- most common cause in children**
- develops in metaphysis (growth plate) of long bones**
- bone necrosis and infection from the stasis of blood
- in infants, spread to epiphysis causing medullary infection –> form involucrum**
- retained to metaphysis from 1–>puberty
- cortical thickening, less involucrum with aging
- in adults, leads to vertebral osteomyelitis** due to rich blood supply (starts in intervertebral disc) –> Staph aureus most common*; also TB –> Pott’s disease** in spine with Gibbus deformity** with kyphosis and anterior vertebrae collapse); brucellosis** –> spine infections that get worse over time; E. coli and Enterococcus** –> Batson’s plexus –> spine and GU infections**
18
Q
osteomyelitis caused by gram neg. rod (ex. E. coli, enterococcus)**
A
GYN infection
-check pelvis from GU infection**
19
Q
vertebral osteomyelitis
A
- starts in disc space and erodes vertebrae**
- lose disc space
20
Q
TB spread to the spine**
A
- Pott’s disease in vertebral osteomyelitis –> anterior wedging with Gibbus deformity**
- excess kyphosis forms
21
Q
batson’s plexus
A
how cancers spread from lungs, breast, prostate into spine
22
Q
osteomyelitis - direct inoculation
A
- mostly from open fractures (ex. ortho surgery)
- direct contact contamination of bone
23
Q
osteomyelitis - contiguous spread
A
-from infections adjacent to bone that enter (ex. septic arthritis, abscesses, periostitis, chronic ulcers)
24
Q
osteomyelitis pathogens***
A
- newborns –> GBS (strep agalactiae)
- young child –> kingella
- nail punctures through shoe –> Pseudomonas
- unvaccinated child –> H. influenza
- sickle cell/thalassemia –> Salmonella
- mandible trauma –> actinomyces
- animal bite –> pasteurella, bartonella, capnocytophaga
- human bite –> eikenella, strep. viridans
- systemic yeast –> histo/blasto/coccidoidomycosis and cryptococcus
- implanted hardware –> staph. coagulase neg., propionibacterium
- old and foreign country –> TB
- immunosuppression –> Pseudomonas, nocardia
25
osteomyelitis pathology
- acute --> neutrophils infiltrate 1st --> bone necrosis
- lymphocytes recruited 2nd
- chronic --> dead bone forms sequestrum (poor penetration of antibiotics) due to body trying to wall area off
- chronic: risks to develop SCC due to sinus tracts**
26
osteomyelitis diagnosis
1. physical: probe to bone test --> osteomyelitis if can tap bone with Q tip
2. lab tests: always high ESR and CRP**, rather obtain bone biopsy than wound cultures (wound pathogen may not be correlated with infection), stop antibiotics 1-2 weeks before biopsy** and send bone off for gram stain
3. X ray - initial test for bone disease**; must lose 50% of matrix to show up (usually neg. in 1st 1-2 weeks of osteomyelitis)
4. sinography/fistulagrams - inject dye into sinus tract then look at CT/Xray to see if it reaches bone
5. nuclear medicine - not good bc WBCs light up with inflammation
6. CT scan - better for looking at bone margins
7. MRI - best for looking at surround soft tissue (can use contrast); diagnostic modality for osteomyelitis**
27
specific types of osteomyelitis
1. diabetic foot infection - neurophathies and vascular diseases
- charcot feet** --> bone shifts
- develop ulcers, decreased immune system
- polymicrobial --> aerobic and anaerobic** --> Staph. aureus and strep from normal flora** and pseudomonas in shoes***
2. osteitis pubis - infection of pubic bones after OB-GYN surgery
3. sternal osteomyelitis - usually after cardiac procedures (ex. coronary bypass)**
- infections due to staph. aureus and staph coagulase neg. species**
- need prolonged antibiotics and debridement
4. sacral osteomyelitis - debilitated patients (para/quadriplegics)
- bed ridden --> develop ulcers
- need prolonged antibiotics and debridement
28
treatment for osteomyelitis
1. debridement - I&D; antibiotics may not be able to get there
- remove hardware or bacteria will be stuck to slime layers/biofilms on surface***
2. antibiotics - usually 4-6 weeks
- emperic therapy** (guessing at what pathogen might be) --> broad spectrum usually
- usually given IV to get into bone vessels easier
3. aggressive wound care
4. vascular eval - ex. bypass or stents if needed
5. antibiotic beads in wound spaces
7. hyperbaric oxygen
29
antibiotic organism targets (pathogen directed therapy)
1. MRSA --> vancomycin, daptomycin, linezolid, ceftroline
2. MSSA --> nafcillin, oxacillin, cefazolin
3. salmonella --> Cipro/levofloxacin
4. Pseudomonas --> ceftazimide
5. strep (group A, B, C, F, G) --> all the cillins
for routine osteomyelitis, mixed aerobic/anaerobic infections, and vertebral osteomyelitis --> vancomycin and daptomycin
-add rifampin if infected, unremovable hardware --> penetrates biofilm
30
septic arthritis
- joint infection due to hematogenous (most common) or contiguous spread or direct inoculation
- induration, heat, and pain around the joint
- loss of joint ROM with effusion (synovial build up)**
- hematogenous spread --> knees>hip>should>wrist>elbow
- direct inoculation --> hands, feet
- differential: many other things look like septic arthritis (ex. inflammatory arthritis, autoimmune, etc.)
- degradation of synovial membrane w/I 48 hours (treat ASAP)** --> synovitis starts and panus develops
- risk groups: IV drug users, RA (highest risk)**, immunosuppressed, diabetes, steroids, endocarditis, EtOH
31
septic arthritis bacterial causes**
- staph aureus most common**
- N. gonorrhea and strep (#2 cause)**
- spirochetes in Lyme disease/syphilis*
- disseminated gonococcal infection (DGI) in sexually active adults under 40*** --> associated with tenosynovitis, polyarthritis, rash, pustules
32
septic arthritis viral causes
- not as common, but can happen
- Parvovirus B19, Hepatitis B/C/E, Rubella, HIV and Chikungunya virus for inflammatory arthritis
- Chikungunya and parvo mimic RA**
33
other bacterial causes of septic arthritis*****
1. H. influenza --> unvaccinated child
2. kingella kingae --> child 2 months - 2 years; found in normal flora
3. GBS and staph aureus --> neonates
4. staph aureus and staph coagulase neg. --> prosthetics
E. *Staph. aureus- after penetrating trauma.
F. *Eikenella and Strep. viridans- after human bites.
G. *Pasteurella, Bartonella and Capnocytophaga- after animal bites.
H. *Pseudomonas aeruginosa- after nail punctures through shoes and in snake bites.
I. *Spirillum minus and Streptobacillus moniliformis- in rat bites (the two causes of rat bite fever)
34
disseminated gonoccocal Infection (DGI)**
- most common cause of septic arthritis in sexually active under 40**
- 3x more common in women due to period**
- problems in those with terminal compliment pathway deficiency*
35
septic arthritis diagnosis
1. blood tests - always high ESR/CRP***
2. joint/synovial fluid studies - arthrocentesis
- fluid less viscous with inflammatory processes (no string sign and is cloudy)
- bacterial arthritis: elevated LDH and WBCs (neutrophils) usually
- fungal/mycobacterial arthritis: autoimmune diseases like gout, pseudo gout
3. synovial tissue studies - synovial biopsy
4. blood cultures may/may not be positive
36
agar for N. gonorrhea**
Thayer Martin blood agar
37
gout vs. pseudo gout**
- gout --> need-like crystals
| - pseudogout --> rhomboid like crystals
38
radiology of septic arthritis
1. x ray - not sensitive
2. nuclear medicine bone scans - nonspecific
3. CT scan - show bone abnormalities
4. MRI - best diagnostic tool**, soft tissue around joint
39
septic arthritis treatment
- viral --> no treatment
- bacterial --> decompression/drainage (arthrocentesis)
- antibiotic coverage to a single pathogen bc that is normally the cause
- use vancomycin (covers staph/strep) and ceftriaxone (covers gram neg rods, H. influenza, N. gonorrhea)
40
specific types of septic arthritis
1. septic prosthetic joint arthritis: infection of prosthetic joints (knees most common)
- lead to prosthesis loosening
- due to staph. aureus or staph coagulase neg species**
2. septic sternoclavicular and sternocostal joint arthritis - usually IV drug abusers or infected central line
- need debridement and longterm antibiotics
3. septic sacroiliac joint arthritis: IV drugs users or from infected sacral ulcer
- need debridement and longterm antibiotics
4. reactive arthritis: maybe from infection elsewhere or immune related inflammation
- ex. post-streptococcal arthritis (rheumatic fever), chlamydia STI (Reiter's syndrome), and GI infections
- HLA-B27 gene associated****
5. septic bursitis: puncture bursa causing skin flora and other bacteria to enter --> do I&D and antibiotics
- usually staph aureus***
- usually prepatellar and olecranon bursae
41
muscle infections
1. causes: hematogenous, direct inoculation, contiguous
2. pathology: myalgia due to myositis from acute phase reactants (IL-1, TNF-alpha) released in host immune rxn
- pyomyositis if infected by bacteria
3. organism: usually staph aureus and strep species**
- TB also common cause of muscle abscess
- can be polymicrobial
4. diagnosis: x ray, ultrasound, nuclear medicine
- CT and MRI best for looking muscle infection, abscess, and surrounding inflammation**
5. treatment: drainage of abscess or debridement
- extensive debridement and fasciotomy if necrotizing fasciitis
- antibiotics always needed
42
pyomyositis
-bacterial infection of muscle - usually from tropical region***
