125. Bone and Joint Infections Flashcards

1
Q

Acute vs subacute infection - timeline?

A

acute within 2 weeks of onset
subacute 1-several months

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2
Q

Compact bone

A

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

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3
Q

Trabecular/spongy bone

A

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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4
Q

Diaphysis

A

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

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5
Q

Metaphysis

A

junctional region epi and diaphysis
trabecular bone and cortical thins here

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6
Q

Epiphysis

A

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

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7
Q

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

A

frictionless movment

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8
Q

Joints - synovial capsule mechanism?

A

structural integrity
sleeve to attach to articulating bones

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9
Q

Osteomyelitis: ?

A

infection of bone and medullay cavity

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10
Q

Osteomyelitis: RF for infection?

A

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

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11
Q

Osteomyelitis: why does infection start at metaphysis

A

area of turbulent blood flow

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12
Q

Osteomyelitis: why is surgery typically needed?

A

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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13
Q

Involucrum

A

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

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14
Q

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

A

readily advances through joint space

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15
Q

Adult progression of OM to joint space?

A

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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16
Q

Gram stain can be negative in OM - how?

A

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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17
Q

Definitive diagnosis of OM?

A

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

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18
Q

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

A

hematogenous

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19
Q

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

A

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

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20
Q

Head and neck OM source of spread?

A

sinus disease
odontogenic infection

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21
Q

Usual source of spread of septic arthritis?

A

hematogenous unless direct source into joint

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22
Q

Typical microbiology of septic arthritis: kids

A

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

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23
Q

Typical microbiology of septic arthritis: young adult

A

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

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24
Q

Typical microbiology of septic arthritis: adult

A

staph > strep > gram neg > gonorrhea > h influ

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25
Q

Typical microbiology of septic arthritis: older adults

A

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

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26
Q

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

A

puncture wounds
post surgical
sickle cell anemia

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27
Q

Underlying disease RF for bone-joint infection risk

A

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

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28
Q

Empiric abx for neonate to <3mo with OM

A

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

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29
Q

Empiric abx for neonate to <3mo with Septic arthritis

A

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

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30
Q

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

A

S aureus
gbs
enterbacteriaceae

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31
Q

Common organisms 3mo- 14y OM

A

staph aureus
gas
h influ

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32
Q

Common organisms 3mo- 14y septic arthritis

A

s aureus
strep spp
enterbacteriacease

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33
Q

Tx 3mo-14mo om:

A

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

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34
Q

Tx 3mo-14mo septic arhtritis

A

amox clav/septra and ceftriaxone

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35
Q

Tx 14y- adult: what bug for OM?

A

s aureus

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36
Q

Tx 14y- adult: septic arthritis

A

s aureus
strep
enterbacteriaceae

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37
Q

Tx 14y- adult: OM

A

septra or amox clav
alt vanco

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38
Q

Tx 14y- adult: septic arthritis

A

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

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39
Q

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

A

ceftriaxone
or spectinomicin or penicillin if sn

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40
Q

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

A

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

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41
Q

Infection subsets: OM in infected prosthesis - bugs?

A

staoh aureus
staph epidermidis
pseudmonoas

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42
Q

Infection subsets: OM in infected prosthesis - tx?

A

vanco + flq
alt: imipenem

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43
Q

Infection subsets: septic arthris in infected prosthesis - bugs?

A

staph aureus
s epidermidis
pseudomonas (same as OM)

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44
Q

Infection subsets: septic arthris in infected prosthesis - tx

A

vanco + flx
or amox/clav/septra and gentamicin

45
Q

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

A

staph aureus
pseudomonas
enterobactericease

46
Q

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

A

3rd gen cephaosporin and aminoglycoside
or 3rd gen alone

for septic arth: amox calv/septra and gent or flq
or vanco and flq

47
Q

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

A

pseudomonas

48
Q

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

A

ceftrazidie/cefepime
or flq

49
Q

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

A

eikenella corrodons
pasteurella multicoda

50
Q

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

A

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

51
Q

MC forms TB for bone and joint infections?

A
  1. Potts - vertebral OM
  2. Tubercular arthritis - like low grade RA
52
Q

HIV: what bug is particularly characteristic of OM?

A

bacillary angiomatosis
gram negative rikettsia like organism causing ostelytic bone lesions

53
Q

Sx OM:

A

fever
sigos
toxi possible

54
Q

Key sx in children OM?

A

limp, or cannot weight bear

55
Q

Predominant PE finding of septic arthritis

A

point tenderness over infected segment

56
Q

Complications of acute OM

A

bacteremia
sepsis
septic arhtritis
brain abscess
meningitis
spinal cord compression
pneumonia
empyemea

children.= issues of growth

57
Q

OM in children: where is usual site of infection?

A

distal metaphysis due to increased vascularity

58
Q

OM in children: sx

A

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

59
Q

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

A

blood culture (hematogenous spread)
PE

60
Q

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

A

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

61
Q

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

A

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

62
Q

Vertebral OM: RF

A

IV access devices
indwelling lines
asx uti

yo - IVDU

63
Q

Vertebral OM: why is spine so susceptible?

A

two way blood flow
transverse and longitudal anastomoses

64
Q

Vertebral OM: MC areas?

A

lumar
thoracic
cervical

65
Q

Vertebral OM: mc sx?

A

back pain
insiduous onset
tenderness over sp

66
Q

Vertebral OM: Neuro deficits common?

A

only 40%
moreso if + epidural abscess

67
Q

Vertebral OM: helpful labs?

A

esr
crp

blood culture also useful

68
Q

Vertebral OM: tx

A

imaging
start abx empirically
early orth/spine involvement

69
Q

Best imaging test for Vertebral OM:

A

MRI

ct good for bone descrution

70
Q

Cervical OM can cause what ENT disease?

A

retropharyngeal abscess

71
Q

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

A

psoas m abscess

72
Q

Vertebral OM: vascular complications (3)

A

sc ischemia
septic thrombosis
compresion of local bl vessels

73
Q

Vertebral OM: thoracic complications - 3

A

empyema
reactive pleural effusion
paraspinal abscess

74
Q

Vertebral OM: most dreaded complication?

A

infection into spinal canal
epidural abscess
then causing SCI
paralysis

75
Q

Vertebral OM: RF for paralysis from SC progression?

A

oa
cervical spine OM
RA/diabetes

76
Q

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

A
  1. scc
  2. abscess drainage or debridement
  3. correction of progressive anatomic deformity
  4. if infection recurs after adequate tx
77
Q

Diskitis: what is this?

A

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

78
Q

Isolated diskitis is mc in what population?

A

children

79
Q

when to use MRI vs CT for diskitis?

A

anatomy of diskitis

ct - guide aspiration

80
Q

diskitis typical tx op or non?

A

non op

81
Q

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

A

open fracture
burn
bite
puncture wound
surgery and invasive procedure

82
Q

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

A

12

typically not better with pain post surgery

83
Q

What is the treatment choice for infection following TKA?

A

I+D
prosthetic rentesion
following total knee arthroplasty

84
Q

Dx of prosthetic joint infection

A

join aspiration
synovial fluid analysis
bone bx

difficult for imaging given metal

85
Q

Why do people with diabetes get more OM?

A

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 )

86
Q

Radioraphic features of diabeticOM

A

osteopenia
periosteal thickening
cortical erosions
new bone formation
mottled lytic lesions

87
Q

Mainstay of diabetic OM tx?

A

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

88
Q

Why are sickle cell disease pt at risk OM?

A

asplenia

89
Q

Sickle cell OM: where on bone does it effect?

A

diaphysis

90
Q

Sickle cell OM: mc organism?

A

salmonella

91
Q

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

A

fever
toxic appearance
elevate esr
mri

response to conversative therapyY; bone infarct better after 24048h whereas bone infection worsens

92
Q

Chronic OM: clinical signs this has become chronic?

A

formation of sequestra
presence of draining tracts of fistula

93
Q

chronic OM dx: only reliable is…

A

direct bone bx

94
Q

DDX OM

A

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

95
Q

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

A

70

96
Q

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

A

crp - early

97
Q

Early OM on xray - findings?

A

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

98
Q

Children xray OM findings?

A

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

99
Q

More advanced disease OM findings on xray?

A

lytic lesion surrounding dense sclerotic bone
possible sequestra

100
Q

When should CT be used for ID OM?

A

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

101
Q

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

A

bugs may be different than those effecting bone

102
Q

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.

A

-

103
Q

What cases of OM are feasible for medical management?

A

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

104
Q

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

A

corynebacteruim - can cause gas gangrene

105
Q

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

A

feces

106
Q

Septic arthritis: 3 main ways of spread

A
  1. contigious focus of infection
  2. direct inoculation from trauma
  3. iatrogenically after joint aspiration/injection
106
Q

MC organism septic arthritis?

A

staph aureus

107
Q
A