Id - 4-16 - Osteomyelitis

Front 1

How cna organisms enter bone?

Back 1

hematogenous spread or contiguous (inoculation from a focus of infection or wonud)

Front 2

what happens if you don't tx an infected bone

Back 2

becomes chronic ischemic necrosis resulting in separation of large devascularized fragments.

Front 3

pathogenesis of osteomyelitis

Back 3

bacteria binds, can get chronic ischemic necrosis resulting in large devascularized fragments.

when pus breaks through - subperiostial abscesses form and new bone deposits around the sequestrum (devasc fragments of bone)

bacteria are protected by adhering to bone and coating themselves with biofilm.

Front 4

cells of acute and chronic osteomyelitis

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organisms, neutrophils, congested/thrombosed BVs

chronic - few organisms, necrotic bone (absence of living osteocytes), mononuc cells, granulation and fibrous tissue

Front 5

epidem

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more often in males.

the contiguous focus infections and those due to vasc insuff more common in older people

Front 6

hematogenous osteomyelitis in general

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children - long bones (tibia and femur)

adults and IVDA - vertebral

usually in metaphasis (blood supp)

Front 7

slide 7

Back 7

v v important to know

Front 8

acute hematogenous osteomyelitis

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usually a single bone. in children, hard to tell the srouce of bacteria.

blunt trauma can lead to acute hematogenous osteomyelitis

Front 9

pathogens in hematogenous osteomyelitis

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almost always a single pathogen and staph aureus is the most common one.

Front 10

signs/sx of hematogenous osteomyelitis of long bones

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fever, chills, malaise

restriction of movement and pain and edema and difficulty bearing weight.

so the deal with fever... - long bones it is common, vertebral not that common, contiguous almost never.

Front 11

vertebral hematog osteomyelitis - where?

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spinal arteries bring the bacteria to the disc space and then extends to the two end plates of the adjoining vertebra.

usually lumbar and thoracic spine

check for epidural pus!!!

Front 12

vertebralhematog osteomyelitis - bugs

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mots often single organism and staph is most common

but urinary/gastric focus - e coli and other enteric bacilli

IVDA - staph aur, pseudomonas, serratia

sickle cell - salmonella, staph aur

men with big prostate who have to self cath a lot - enterococcus.

Front 13

risk factors for vertebral hematogosteomyelitis

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Age > 50
Sickle cell disease
Diabetes mellitus
Hemodialysis
Endocarditis
Injecting drug use
Nosocomial bacteremia
Long-term vascular access
Urinary tract infection, esp. elderly men
Preceding minor trauma or fall

Front 14

signs/sx for vertebral hematog osteo

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insidious onset. fever is less common than kids who get acute osteomyelitis in long boens)

back/neck pain. systemic sx. percussion tenderness with spasm

Front 15

dx of vertebral hematog osteomyelitis

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esr, crp
cultures are worth getting bc single organism usually
plain films not too useful.
mri is bestbc it can also show epidural, paraspinal, etc. abscesses in the spine

Front 16

signs of child vs adult hematog osteomyelitis

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child - trouble moving limb and febrile

adult - more insiduous, vertebral, check for epidural abscess.

Front 17

now moving on to contiguous focus osteomyelitis

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df

Front 18

causes of contiguous focus osteomyelitis

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Without generalized vascular insufficiency
Related to penetrating injuries
Related to surgery
By direct extension from adjacent soft tissues

With generalized vascular insufficiency
Usually involves the small bones of the feet
Diabetic neuropathy exposes the foot to frequent trauma and pressure sores, and the patient may be unaware of infection as it spreads to bone.
Poor tissue perfusion impairs normal inflammatory responses and wound healing, a milieu conducive to anaerobic infection.

Front 19

site for contiguous focus osteomyelitis

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almost always small bones of the feet

Front 20

bugs for contiguous focus osteomyelitis

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staph aureus most common but more cases are polymicrobial compared to hematog - imp to know this

coag neg staph associated with infections of prostheses

Front 21

signs/sx of contiguous focus osteomyelitis

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with normal vascularity - inflammation, poor ROM, little-no fever

with vasc insuff (e.g. diabetics) - ulcer, cellulitis, localization to small boens of foot, minimal pain.

NOTE THAT THIS IS A MAJOR CAUSE OF AMPUTATION

Front 22

Dx of contiguous focus osteomyelitis

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esr,
crp (espec good because it goes up quickly and then goes down quickly if tx appropriately - tells you if tx is working)

good to get blood cultures

plain film, bone scan, ct or MRI

Front 23

issues with blood cultures are osteomyelitis

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IMPORTANT - BACTERIA FRMO THE SWABBING OF SINUS TRACT OR BASE OF AN ULCER DOES NOT CORRELATE WITH THE ORGANISMS INFECTING THE BONE

always get cultuer before starting abx

Front 24

types of bone scans for osteomyelitis

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plain film - takes long time to see changes (10 days for periosteal rxn and 2-6 weeks for lytic changes) - not v sens or spec

radionuclide/scintigraphy or labeled WBCs - pretty sensitive and spec but thigns like neuropathic arthropathy (diabetes) makes the specificity v v low

CT - not graet. probably only good for chronic osteomyelitis

MRI - most sens and spec. will see bone marrow signal change, cortical bone interruption and soft tissue edema. gives px signs. false positives with fractures, osteonecrosis and occassionally neuropathic joints.

Front 25

what is exposed bone/probe to bone

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you tap bone with metal probe and it makes an "infected" sound

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general principles of tx

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cultre furst
bactericidal agents
atleast empiric coverage for staph aureus

start high doses of IV abx

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streptococci tx

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penicillin g

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staph aureus tx

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need to just go for the vanco because so much MRSA otu there (nafcillin and oxacillin won't work on mrsa. neither will any cephs)

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gram neg bacilli tx

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ampicillin, cefazolin, ceftriaxone or quinolone

Front 30

pseudomonas aeruginosa

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combo of aminoglycoside and beta lactam or quinolone

Front 31

tx of acute hematogenous osteomyelitis

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4-6 weeks of tx
home therpaty can work well

children - 5-10 days of parenteral then oral

adults- cant do oral

Front 32

tx of vertebral osteo

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check for epidural abscess.

6 weeks.

surgery with neuro deficits (relieve pressure in spinal cord)

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tx of chronic osteomyelitis

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HALLMARK IS NECROTIC BONE

combo of surg and med (need to debride to necrotic bone)

get imaging before surgery.

after surg, parenteral therapy based on culture.

Front 34

tx of contiguous osteomyelitis with vascular insuff

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debridement (revascularize the limb first)

poor px if you don't remove all the infected bone

Front 35

skeletal tuberculosis

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usually thoracic spine with abnormal CXR

suspect tb with they travel history, x ray findings, ppd or interferon release assay, etc)

histopath - necrotizing granulomas but the infection is paucibacillary so stains may be neg and cultures take a while.

so start tx early if suspicion is high.