SSTI, Bone and Joint

Question 1

Complication of furuncle/carbuncle involving nares or medial third of face

Answer 1

cavernous sinus thrombosis

Question 2

SSTI a/w freshwater, estuarine (brackish) water, floodwater

medicinal leeches

Answer 2

aeromonas

→ cellulitis, traumatic wound infection, myonecrosis, necrotizing SSTI

Tx: 3rd gen ceph, FQ, bactrim

*for pts receiving leech therapy - give ppx cipro

Question 3

tx for vibrio

Answer 3

doxy + CRO/cefotax

Question 4

SSTI + handling raw seafood

Answer 4

• vibrio - shellfish, liver/iron disease
• erysipelothrix - shrimp, crab, fish

Question 5

SSTI + foot baths, nail salon

Answer 5

M fortuitum

Question 6

Dx criteria for burn wound sepsis

Answer 6

• presence of clinical features of infection and systemic signs
• wound bx = bacterial count >10⁵/gm of tissue w/ evidence of invasion into unburned tissue on histopath

Question 7

SSTI that develop rapidly w/in 48hrs of surgery

Answer 7

think GAS and Clostridium

Question 8

animal hide/wool

pruritic papule → vesicles/bullae → ulcerate → painless black eschar w/ surrounding induration

Answer 8

cutaneous anthrax

tx w/ cipro or doxy x60 days

Question 9

Organisms whose growth is stimulated by excess iron

Answer 9

“VELARY” = the sails of a ship

• Vibrio
• E coli
• Listeria
• Aeromonas
• Rhizopus spp (Mucor)
• Yersinia enterocolitica

Question 10

SSTI a/w oysters

rapid onset - red, painful, hemorrhagic bullae

• diagnosis and RF
• Tx

Answer 10

vibrio vulnificus

• liver disease (EtOH, hemachromatosis, etc)
• Tx: doxy + CRO (alt = FQ)

Question 11

on a certain medication

fluctuant tender furuncle

F, generalized erythroderma (bullous lesions develop)

skin bx: intra-epithelial split in skin

Answer 11

Staph aureus SSS

Question 12

Strep vs Staph TSS

• predisposition
• focal pain - y/n
• tissue necrosis/inflammation
• N/V, renal failure, DIC - y/n
• erythroderma
• bacteremia
• mortality

Answer 12

• staph: tampon, surgery, colonization; strep: cuts, burns, erysipelas, varicella
• staph: no; strep: yes
• staph: rare; strep: common
• staph and strep: yes
• staph: very common; strep: less common
• staph: very rare; strep: 60%
• staph: <3%; strep: 30-70%

Question 13

after cut/abrasion exposure to swine or fish

severe throbbing pain

Answer 13

erysipelothrix (GPR)

• Dx: culture (aspirate/bx)
• Tx: PCN, cephs, clinda, FQ

Question 14

Answer 14

Bullous impetigo

Staph

***good theme for boards:

• honey-crusted: strep
• bullae = staph

Question 15

Answer 15

Strep impetigo

Strep: groups A, B, C, G

Question 16

etiologies for folliculitis

Answer 16

1. SA
2. PSAR (hot tub)
3. Candida (obese pt)
4. Malassezia furfur = lipophilic yeast
5. AIDS = idiopathic eosinophilic pustular folliculitis

Question 17

anaerobic small GNR

human bite injury

dx and tx

Answer 17

eikenella

Susc: PCN, FQ, TMP/SMX, doxy

R: clinda, keflex, metronidazole

**amox/clav = TOC for human bites

Question 18

homeless w/ animal bites

contaminated water/food

fever, extremity rash

symmetrical polyarthralgias

Answer 18

rat bite fever (Strep moniliformis)

tx: PCN, doxy

Question 19

tx for capnocytophaga

Answer 19

amox/clav

can use zosyn, PCN, clinda (add clinda if needing to use other abx for tx of animal bite, such as bactrim or doxy)

R to: bactrim, ?vanc

Question 20

pathogens in dog bites

Answer 20

• pasteurella
• capnocytophaga (splenectomy, liver disease)
• human skin: SA, strep pyogenes

Question 21

6 pathogens that can cause infection after cat bites

Answer 21

• pastuerella
• anaerobes
• bartonella henselae
• rabies
• S aureus
• Strep spp

Question 22

imaging abn at pubic symphysis (bone marrow edema w/ some symmetric bone erosions)

negative cultures and bxs

unresponsive to abx courses

pt with waddling gait

Answer 22

consider osteitis of the pubic symphysis

noninfectious - a/w radiation, vaginal delivery

Question 23

spinal osteo as sacroiliitis or spondylodiscitis

Answer 23

think of brucellosis (w/ risk factors)

Question 24

Bone/joint infection

+

Cat/dog bite

Answer 24

pasteurella spp

Question 25

Symmetric polyarthritis (usually of small joints) - often a/w fever/rash -- think viral Immune-complex arthritis a/w cryoglobulinemia

Answer 25

think HCV

Question 26

Bone/joint infection + human bite wounds recent dental procedures

Answer 26

HACEK | (eikenella w/ human bite)

Question 27

Bone/joint infection + NE/upper MW tick exposure **subacute mono**arthritis (knee MC) w/ **large effusion**

Answer 27

lyme

Question 28

Bone/joint infection + children \< 4yo Grows poorly in cx (dx via PCR)

Answer 28

kingella kingae

Question 29

young adults with asymmetric oligoarthritis + urethritis, uveitis, or conjunctivitis dx and what IDs are a/w?

Answer 29

**Reactive arthitis** (sterile inflammation 2/2 dysregulated immune response from antecedent infection) * C. trachomatis (can be seen via NAAT in urine) * Shigella * Salmonella * Campy * Yersinia

Question 30

lab testing for suspected disseminated gonococcal infection

Answer 30

**include indirect testing (via mucosal NAAT)** **With septic arthritis: NAAT may be helpful, but not FDA-approved**. Blood cultures are low-yield culturing requires chocolate agar or Thayer-Martin medium

Question 31

Bone/joint infection + Madura foot (barefoot walking) environmental contamination IC hosts (neutropenic)

Answer 31

molds

Question 32

* Symmetric polyarthritis (usually of small joints) - often a/w fever/rash -- think viral * serum-sickness like reaction, resolves with development of jaundice * often also polyarteritis nodosa

Answer 32

think HBV

Question 33

_Late Non-union_: * Micro: * Surgical Strategy: * Abx management:

Answer 33

* Indolent (CoNS, cutibacterium) * HW removal, revision fixation * Path-directed tx

Question 34

septic arthritis negative cx (or delayed cx)

Answer 34

_think_: gonococcus, HACEK, lyme, mycoplasma

Question 35

bone/joint infection + splenic dysfunction

Answer 35

Strep pneumo

Question 36

Bone/joint infection + humoral deficiency postpartum women tough to grow on cx **Fried egg** on culture

Answer 36

mycoplasma spp

Question 37

2 locations of septic arthritis that should raise suspicion of IVDU

Answer 37

* sternoclavicular joint * SI joint

Question 38

Bone/joint infection + IC host, indwelling line, IUD

Answer 38

PSAR

Question 39

Symmetric polyarthritis (usually of small joints) - often a/w fever/rash -- think viral women, history of exposure to young children (teacher, parent) hands often involved

Answer 39

parvo B19

Question 40

* Tenosynovitis (esp extensor surface) * Migratory arthralgias * purulent arthritis (often w/ lower PMN count)

Answer 40

**gonococcal arthritis** ## Footnote _Highest yield dx_: **mucosal site sampling (cervical, urethral)**. Blood (\<30%) and synovial fluid (\<50%) lower yield + compatible syndrome

Question 41

bone/joint infection + fight bite, oral flora, contamination of IVDU

Answer 41

think of Eikenella and peptostreptococcus

Question 42

_Early/delayed infections prior to fx union_ * Micro: * Surgical Strategy: * Abx management:

Answer 42

* SA = MC * Debride and retain (assuming implants fixed well) * Path-directed; rifampin + if staph

Question 43

vertebral osteo (thoracic\>lumbar) anterior involvement --\> kyphosis deformation sparing disc space (until later)

Answer 43

think Pott's disease indolent presentation

Question 44

Bone/joint infection + unpasteurized dairy travel to endemic regions (Latin Am, Mediterranean, Middle East) **sacroiliitis, spondylodiscitis**

Answer 44

Brucella spp

Question 45

cutibacterium acnes in seeing of PJI

Answer 45

often a/w shoulder PJI

Question 46

Symmetric polyarthritis (usually of small joints) - often a/w fever/rash -- think viral + travel

Answer 46

always consider alphaviruses (esp Chik)

Question 47

Bone/joint infection + tenosynovitis Dermatitis arthritis

Answer 47

N gonorrhea

Question 48

Bone/joint infection + IC hosts, IDU

Answer 48

candida spp

Question 49

bone/joint infection + brackish water, water exposure/contamination

Answer 49

Think aeromonas (esp "brackish" water) also consider pseudomonas

Question 50

bone/joint infection + malignancy

Answer 50

think of GBS

Question 51

Symmetric polyarthritis (usually of small joints) - often a/w fever/rash -- think viral non-immune (not born in US), cervical LAD

Answer 51

rubella

Question 52

rash, high fevers, arthritis (\>10joints) Asia, Africa, Europe, Caribbean relapsing-remitting or unremitting Dx and testing

Answer 52

think of Chik RT-PCR if within 1wk of sx serology if sx \>1wk (IgM can be detected up to 3mos)

Question 53

Bone/joint infection + SCD DM IC reptile exposure travel to developing world unsafe food hygiene +/- GI illness

Answer 53

salmonella

Question 54

PJI Management Table

Answer 54

Question 55

HCV arthritis

Answer 55

* typically RA-like pattern (symm wrists, MCP, PIPs) * also can be oligoarthritis w/ large joints (**a/w mixed essential cryoglobulinemia**) * d/t immune complex formation

Question 56

walled off intra-osseous abscess of metaphyseal bone (surrounded by rim of sclerotic bone) in children/young adults

Answer 56

**brodie's abscess (subacute hematogenous osteo)** * MC d/t SA * "penumbra sign" = granulation tissue lining abscess cavity -- looks like double line