125. Bone and Joint Infections Flashcards by Tegan Turner

Acute vs subacute infection - timeline?

acute within 2 weeks of onset
subacute 1-several months

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Compact bone

compact - shaft of long bone and covers epiphysis
- dense, without cavities, longitudinaly running Haversian systems (house vasculature and nerves)

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Trabecular/spongy bone

trabecular - within epiphysis and makes up irregular bone
- bony lattice, traveculae, which located within medullary cavity and contains marrow, more metabolically active
-central Haversian canals in spongy bone parallel to long axis of bone - bloody supply and reticular ct for haversian system

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Diaphysis

shaft of bone
compact cortical bone overlying periosteum and medullary canal containing marrow

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Metaphysis

junctional region epi and diaphysis
trabecular bone and cortical thins here

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Epiphysis

area at either end of a long bone and made of abundant trabecular bone
thin shell cortical bone

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Cartilage in a mature adult on the epiphysis of bone - what does this allow?

frictionless movment

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Joints - synovial capsule mechanism?

structural integrity
sleeve to attach to articulating bones

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Osteomyelitis: ?

infection of bone and medullay cavity

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Osteomyelitis: RF for infection?

trauma
distruption of blood flow
large inoculum of bloodborn or external microorganisms
FB

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Osteomyelitis: why does infection start at metaphysis

area of turbulent blood flow

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Osteomyelitis: why is surgery typically needed?

inflammatory cell migration to the area to help causes edema, vascular congestion and small vessel thrombosis so that IO pressure increases to compromise flow to bone - as such medication hard to get here

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Involucrum

new bony tissue growth at area of infection to compensate for tensile stress from lack of blood supply

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Why do neonates and infant more often get septic arthritis from OM?

readily advances through joint space

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Adult progression of OM to joint space?

post epi plate fusion –> anastomoses between metaphyseal and epiphyseal blood vessel fro infection to spteady to epi, then synovium and joint space

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Gram stain can be negative in OM - how?

only picks planktonic/bacteria in a single state (typically those least R) - therefore often times biofilm other stages are still virulent

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Definitive diagnosis of OM?

can only be done by culture of synovial fluid aspirate or synovial tissue

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Source of spread of bacteria in children’s OM and adult vertebral OM?

hematogenous

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Source of spread of bacteria in appenduclar skeleton adult (foot, hand, skul, maxilla, mandible) OM?

contigious source infection
direct implantation (bite, open fracture, surgical instrumentation)

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Head and neck OM source of spread?

sinus disease
odontogenic infection

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Usual source of spread of septic arthritis?

hematogenous unless direct source into joint

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Typical microbiology of septic arthritis: kids

staph aureus > strep > gram neg, neisseria > H influ

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Typical microbiology of septic arthritis: young adult

neisseria > staph > strep, gram neg and h influ rare

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Typical microbiology of septic arthritis: adult

staph > strep > gram neg > gonorrhea > h influ

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Typical microbiology of septic arthritis: older adults

staph > gram neg > strep > rare h influ, gonorrhea

In what pt pop does pseudmonas need to be strongly considered as a source of septic arthritis?

puncture wounds post surgical sickle cell anemia

Underlying disease RF for bone-joint infection risk

diabetes chronic steroid IVDU preexisting joint disease (RA) other immunosuppressed states

Empiric abx for neonate to <3mo with OM

cephalosporin third gen Penicillinase R pen like amox clav or vanco (if MRSA) +gent

Empiric abx for neonate to <3mo with Septic arthritis

amox clav + ceftriaxone or amox clav and gent if MRSA + switch amox clav for vanco

Common organisms OM and septic arthritis for neonates and children <3mo

S aureus gbs enterbacteriaceae

Common organisms 3mo- 14y OM

staph aureus gas h influ

Common organisms 3mo- 14y septic arthritis

s aureus strep spp enterbacteriacease

Tx 3mo-14mo om:

ceftriaxone + amox clav/septra or vanco and ceftri, chloramphenicol amox clav or ceftr with allergy pen or clinca with allergy to pen + ceftr

Tx 3mo-14mo septic arhtritis

amox clav/septra and ceftriaxone

Tx 14y- adult: what bug for OM?

s aureus

Tx 14y- adult: septic arthritis

s aureus strep enterbacteriaceae

Tx 14y- adult: OM

septra or amox clav alt vanco

Tx 14y- adult: septic arthritis

amox clav/septra or ceftr alt: vanco and cetr or penicillin and gent or ceftr

Infection subsets: septic arthritis in a yung sexually active adult or adult with acute arhthrits concern for gonorrhea - tx?

ceftriaxone or spectinomicin or penicillin if sn

Infection subsets: OM in chronic OM and db foot infrection tx:

amox clav or septra + flq + metronidazole or amoxclav/septra + ceftr + clinda

Infection subsets: OM in infected prosthesis - bugs?

staoh aureus staph epidermidis pseudmonoas

Infection subsets: OM in infected prosthesis - tx?

vanco + flq alt: imipenem

Infection subsets: septic arthris in infected prosthesis - bugs?

staph aureus s epidermidis pseudomonas (same as OM)

Infection subsets: septic arthris in infected prosthesis - tx

vanco + flx or amox/clav/septra and gentamicin

Infection subsets: OM/septic arhtritis n IVDU - bugs?

staph aureus pseudomonas enterobactericease

Infection subsets: OM/septic arhtritis n IVDU - tx?

3rd gen cephaosporin and aminoglycoside or 3rd gen alone for septic arth: amox calv/septra and gent or flq or vanco and flq

Infection subsets: plantar puncture wound OM/septic arthritis - bug?

pseudomonas

Infection subsets: plantar puncture wound OM/septic arthritis - tx?

ceftrazidie/cefepime or flq

Infection subsets: human or animal bite OM/septic arthritis risk- bugs?

eikenella corrodons pasteurella multicoda

Infection subsets: human or animal bite OM/septic arthritis risk- tx?

pencillin +/- cefepime or ceftazidine or 3rd gen cephalosporin and septra

MC forms TB for bone and joint infections?

1. Potts - vertebral OM 2. Tubercular arthritis - like low grade RA

HIV: what bug is particularly characteristic of OM?

bacillary angiomatosis gram negative rikettsia like organism causing ostelytic bone lesions

Sx OM:

fever rigor toxi possible

Key sx in children OM?

limp, or cannot weight bear

Predominant PE finding of septic arthritis

point tenderness over infected segment

Complications of acute OM

bacteremia sepsis septic arhtritis brain abscess meningitis spinal cord compression pneumonia empyemea children.= issues of growth

OM in children: where is usual site of infection?

distal metaphysis due to increased vascularity

OM in children: sx

fever chills vomit dehydration malaise not usually toxic point tender limp or cannot weight bear

OM in children: what 2 things are sign for dx?

blood culture (hematogenous spread) PE

OM in children: subacute osteomyeltitis - what might this look like?

s+sx slow to appear radiographs show small areas of OM in metaphysis cultures often negative

OM in children: chronic recurrent multifocal OM - what might this look like?

small foci of infection defined by mult episodes of indolent infection culture often negative, xr help

Vertebral OM: RF

IV access devices indwelling lines asx uti yo - IVDU

Vertebral OM: why is spine so susceptible?

two way blood flow transverse and longitudal anastomoses

Vertebral OM: MC areas?

lumar thoracic cervical

Vertebral OM: mc sx?

back pain insiduous onset tenderness over sp

Vertebral OM: Neuro deficits common?

only 40% moreso if + epidural abscess

Vertebral OM: helpful labs?

esr crp blood culture also useful

Vertebral OM: tx

imaging start abx empirically early orth/spine involvement

Best imaging test for Vertebral OM:

MRI ct good for bone descrution

Cervical OM can cause what ENT disease?

retropharyngeal abscess

Vertebral OM: L spine OM can be complicated with which other ortho disease?

psoas m abscess

Vertebral OM: vascular complications (3)

sc ischemia septic thrombosis compresion of local bl vessels

Vertebral OM: thoracic complications - 3

empyema reactive pleural effusion paraspinal abscess

Vertebral OM: most dreaded complication?

infection into spinal canal epidural abscess then causing SCI paralysis

Vertebral OM: RF for paralysis from SC progression?

oa cervical spine OM RA/diabetes

Vertebral OM: when does surgery need to be considered in addition to IV abx?

1. scc 2. abscess drainage or debridement 3. correction of progressive anatomic deformity 4. if infection recurs after adequate tx

Diskitis: what is this?

varient of vertebral OM: disk is avascular and gets nutrition from nearby blood vessels, so possible for bacteria o flourish here

Isolated diskitis is mc in what population?

children

when to use MRI vs CT for diskitis?

anatomy of diskitis ct - guide aspiration

diskitis typical tx op or non?

non op

What kinds of injuries/general categories can cause posttraumatic OM?

open fracture burn bite puncture wound surgery and invasive procedure

When to prosthetic joint OM from surgery typically display themselves? (weeks)

12 typically not better with pain post surgery

What is the treatment choice for infection following TKA?

I+D prosthetic rentesion following total knee arthroplasty

Dx of prosthetic joint infection

join aspiration synovial fluid analysis bone bx difficult for imaging given metal

Why do people with diabetes get more OM?

compromised vascularity polyneuropathy hyperglycemia impairs healing ( allows bacteria to proliferate, impaired wbc function, defective chemotaxis, abn phagocytosis, decr bactericidal function, defect abody synthesis, decr completement )

Radioraphic features of diabeticOM

osteopenia periosteal thickening cortical erosions new bone formation mottled lytic lesions

Mainstay of diabetic OM tx?

amp also can try 10 week abx tx *IV then oral in select pt

Why are sickle cell disease pt at risk OM?

asplenia

Sickle cell OM: where on bone does it effect?

diaphysis

Sickle cell OM: mc organism?

salmonella

Sickle cell OM: bone infarction vs OM - ways to consider oM more likely?

fever toxic appearance elevate esr mri response to conversative therapyY; bone infarct better after 24-48h whereas bone infection worsens

Chronic OM: clinical signs this has become chronic?

formation of sequestra presence of draining tracts of fistula

chronic OM dx: only reliable is...

direct bone bx

DDX OM

osteoid osteomas, chondoblastoma, metastases, lymphoma Ewing sarcuma occult fracture

For diabetes, what level of ESR ("greater than ?") incr likelihood of underlying bone infection

CRP and ESR - which is better for early onset disease vs following resolution

crp - early

Early OM on xray - findings?

lucent lytic areas of cortical bone descrution (often takes 2 weeks though so can miss if early) 3-5d: soft tissue edema distorted fascial planes altered fat

Children xray OM findings?

periosteal reaction - hypertrophy or elevation of periosteum and presence of involucrum

More advanced disease OM findings on xray?

lytic lesion surrounding dense sclerotic bone possible sequestra

When should CT be used for ID OM?

when MRI CI/unavailable for assessing involucrum, sequestrum better view than plain of sternum, vertebrae, pelvis bones, calcaneus

Why is a swab not reliable/acceptable for dx of OM?

bugs may be different than those effecting bone

OM Dx *A few key points should be considered with use of this algorithm: * Radiographs lag behind the clinical picture. * In infants and children, the amount of radiation exposure with imaging techniques must be considered. * If the clinical presentation strongly suggests osteomyelitis, a lengthy diagnostic evaluation should not delay empirical treatment. Culture specimens of blood, urine, and other appropriate sites should be obtained and antibiotic treatment started. * Early osteomyelitis is best identified on MRI with contrast. Other imaging modalities are useful later in the disease course and play an important role, especially when MRI is unavailable or contraindi- cated, and in concert with other clinical and laboratory findings.

What cases of OM are feasible for medical management?

asymptomatic OM for pt with fever, w loss or bacteria, hematongeous infection/vertebral OM caused by sn bacteria

Penicillin is reserved for bone contaminated with soil to cover which bug?

corynebacteruim - can cause gas gangrene

Penicillin and gentamicin are reserved for bone infections contaminated with what?

feces

Septic arthritis: 3 main ways of spread

1. contigious focus of infection 2. direct inoculation from trauma 3. iatrogenically after joint aspiration/injection

MC organism septic arthritis?

staph aureus

Waldvogel classification for OM

hematogenous contiguous - vascular insuff or none chronic

125. Bone and Joint Infections Flashcards

(108 cards)