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Musculoskeletal > Micro: Cross > Flashcards

Micro: Cross Flashcards

1
Q

Tx of septic arthritis

  1. gram pos. cocci
  2. GNR
  3. neg. gram stain
A
  1. vancomycin
  2. cephalosporin or zosyn (piperacillin-tazobactam)
  3. vancomycin plus cephalosporin
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2
Q

most common organism for septic arthritis

A

S. aureus

next: streptococcus (GAS, GCS, GGS; GBS in neonates, DM, malignancies; GBS can be polyarticular; S. pneumoniae (less common))
other: coag. negative staph

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3
Q

Risk factors for septic arthritis

A 
most common: PREEXISTING ABNORMAL JOINT ARCHITECTURE (gout, RA, osteoarthritis, etc)
1. advanced age
2. DM
3. previous joint surgery
4. IVDU
5. endocarditis
6. immunosuppression
1/4 don't have identifiable risk factor
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4
Q

Most common source of infection in septic arthritis

A

HEMATOGENOUSLY

other: direct inoculation (trauma, Sx, bite, percutaneous), spread from soft tissue

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5
Q

gram neg. bacilli for septic arthritis

  1. IVDU, iatrogenic (SURGERY or INTRA-ARTICULAR injection)
  2. young adults, late complement deficiency
  3. sickle cell and SLE
  4. cat or dog bite
  5. unpasteurized
  6. RA
A

at risk: elderly, immunocompromised, neonates, IVDU

  1. P. aeruginosa (staph aureus also common in IVDU)
  2. Neisseria gonorrhea, Neisseria meningitidis
  3. Salmonella
  4. Pasteurella multocida
  5. Brucella
  6. staph aureus most common
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6
Q

septic arthritis: N. gonorrhoeae

A

young sexually active adults (women more common, lower SE status, non-white, MSM, multiple partners, illicit drug use)
C5-C8 DEFICIENCY; splenectomy
dysuria, abnormal vaginal discharge
DERMATITIS: nonpuritic SKIN lesions, TENOSYNOVITIS, polyarthralgia
risk: menstruation, pregnancy, postpartum, C5-8 deficiency, ALE

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7
Q

alpha toxin (lecithinase)

A 
C. perfringens
traumatized tissue (especially muscle)
damage cell membranes including RBCs
produce GAS in tissue
HEMOLYSIS: anemia
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8
Q

C. perfringens

A

ANAEROBIC GPR
gas gangrene: MYONECROSIS, NECROTIZING FASCIITIS
Sx: pain, edema, cellulitis, CREPITUS, HEMOLYSIS
SPORE: contaminated wound
ALPHA TOXIN
high mortality: shock
Dx: smear of tissue and exudate (GPR), cultures anaerobically: SUGAR FERMENTATION and ACID production, DOUBLE ZONE HEMOLYSIS
Tx: penicillin G

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9
Q

Lyme disease

A

TICK BITE
NORTHERN states, NE (not here in south)
early stage I: ERYTHEMA MIGRANS
early stage II: smaller skin lesions, malaria rash, conjunctivitis, heart and nervous system (palsies and meningitis, AV block)
late: intermittent arthritis (resolves in years without Tx, can use antibiotic to treat but may be refractory to it)
Dx: Lyme Western blot

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10
Q

MTB osteomyelitis

A 
hematogenous spread from lungs
PPD, back pain with Hx of TB (treated or not)
neg. culture
GRANULOMA and CASEATION
Pott's: VERTEBRAE
Sx: abcesses
Tx: RIPE
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11
Q

Osteomyelitis in IVDU

A

S. aureus (MRSA) and Pseudomonas
also: Candida
unusual sites of infection are common: sternoclavicular, sternochondral joint, pubic symphysis

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12
Q

Iatrogenic effect: osteomyelitis

A 
STAPH
doctor did it
ALWAYS ask if had recent steroid injection in back
potential source of infection
Dx: blood culture
Tx: broad spectrum antibiotics
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13
Q

staphylococci

A

G+ cocci in grapelike clusters

catalase

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14
Q

catalase

A

STAPH

degrade H202: limits neutrophil ability to kill

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15
Q

staphylococcus aureus diseases

A

normal flora
toxins, pyogenic inflammation
abscesses, septic arthritis, osteomyelitis, endocarditis, food poisoning, scalded skin syndrome, TSS
hospital-acquried PNA leading to empyema/abscess, septicemia, mastitis, surgical wound infections
folliculitis, impetigo, bacterial conjunctivitis

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16
Q

staphylococcus epidermidis

A

SKIN, MUCOUS MEMBRANES
catalase, NO coagulase, non hemolytic, UREASE, does not ferment mannitol, NOVOBIOCIN sensitive
endocarditis, prosthetic join/hardware infections, IV catheters
BIOFILM

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17
Q

staphylococcus saprophyticus

A

catalase, coag neg., non-hemolytic, UREASE, does not ferment mannitol, novobiocin resistant
UTI (sex within last 24 hours)
Tx: bactrim or ciprofloxacin

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18
Q

staphylococcus aureus

A 
NOSE, SKIN, some vaginas
toxins and pyogenic inflammation
catalase, coagulase, staphloxanthin, hemolysin, protein A, teichoic acid, polysaccharide capsule, peptidoglycan, alpha toxin
beta hemolysis, ferments mannitol
produce beta lactamase 
CHILDCARE center, IVDU, PRISON, SPORTS
can produce biofilm
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19
Q

coagulase

A

staph aureus
activates prothrombin to thrombin causing activation of fibrinogen to fibrin to form clots
walls off infected site and delays NEUTROPHIL migration to site
test done with RABBIT plasma

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20
Q

beta hemolysis

A

complete lysis of RBC on blood agar
staph aureus
GAS, GBS, GCS/GGS

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21
Q

mannitol fermentation

A

staph aureus

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22
Q

beta lactamase

A

degrades penicillin

staph aureus

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23
Q

mecA gene

A

staph aureus: MRSA

encodes altered penicillin binding proteins in beta-lactamase-resistant penicillins (methicillin)

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24
Q

staphyloxanthin

A

staph aureus
carotenoid: causes golden color to colonies
inactivates microbicidal effect of SUPEROXIDES and other ROS in neutrophils

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25
Q

hemolysins

A

staph aureus

hemolyze RBC to use iron for growth

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26
Q

peptidoglycan

A

staph aureus
stimulates macrophages to produce cytokines, activates complement/coagulation cascades
SEPTIC SHOCK without endotoxin

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27
Q

protein A

A

staph aureus
cell wall protein
binds Fc (complement binding site) of IgG and prevents complement activation
NO C3b produced: reduced phagocytosis

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28
Q

teichoic acid

A

staph aureus
mediate adherence of staph to mucosal cells
lipoteichoic acid induces IL-1 and TNF from macrophages

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29
Q

polysaccharide capsule

A

staph aureus
11 serotypes: 5 and 8 most commonly cause infection
allows bacteria to attach to artificial materials and resist host cell phagocytosis
also: GAS, GBS

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30
Q

alpha toxin/hemolysin

A

staph aureus
membrane-damaging hemolytic toxin
forms holes in host cells
causes necrosis of skin and hemolysis

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31
Q

panton valentine (P-V) leukocidin

A

staph aureus: necrotizing PNA, skin/soft tissue infection, COMMUNITY ACQUIRED MRSA
membrane-damaging hemolytic toxin
pore forming cytotoxin that causes leukocyte destruction by damaging cell membranes and causes tissue necrosis
cell contents leak out of pore

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32
Q

gamma-toxin/leukotoxin

A

staph aureus
membrane-damaging hemolytic toxin
lyses phagocytes and RBC

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33
Q

scalded skin syndrome

A 
staph aureus
EXFOLIATIVE TOXIN A and B
NEWBORNS
Sx: fever, irritable, diffuse blanching erythema with blisters/bullae a couple days later on flexural areas, butt, hands and feet, serous fluid exudates, dehydration, electrolyte imbalance, FLAKY DESQUAMATION as lesions heal
NO SCARRING, recover in 10 days
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34
Q

exfoliatin/exfoliative toxins A and B

A

staph aureus: scalded skin syndrome, bullous impetigo

protease that cleaves desmoglein in desmosomes leading to separation of epidermis at the granular cell layer

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35
Q

enterotoxin A

A

staph aureus: food poisoning
vomiting (caused by cytokines that stimulate enteric nervous system to activate vomit center in brain), watery diarrhea
acts as SUPERANTIGEN in GI tract
stimulates IL-1, IL-2 from macrophages and helper T cells
heat resistant: not inactivated by brief cooking, resistant to stomach acid/enzymes
incubate 1-8 hours

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36
Q

bullous impetigo

A 
staph aureus
EXFOLIATIVE TOXIN: localized
vesicles flaccid bull with clear yellow fluid, later darker and more turbid
ruptured bull leave thin brown crust
TRUNK
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37
Q

staph toxic shock syndrome

A

staph aureus
SUPERANTIGEN: TSST
tampons, nasal packing, post op infection, other infections
local infection spreads to blood stream
IL-1, IL-2, TNF
blood cultures NEGATIVE
Sx: fever, hypotension, dizzy, diffuse macular erythroderma that desquamates 1-2 weeks after onset, vomit/diarrhea, severe myalgia, CPK elevates, renal failure, transaminitis, hyperbilirubinemia, thrombocytopenia, AMS

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38
Q

Tx of MSSA

A

nafcillin/oxacillin, cephalosporins (cefazolin, ceftriaxone, cefepime, ceftaroline)
vancomycin
augmentin (mild infections)
resistant to PCN (produce beta lactamase)

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39
Q

Tx of MRSA

A

vancomycin, daptomycin
linezolid
ceftaroline
mild: bactrim, clindamycin, doxycycline

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40
Q

Tx VISA/VRSA

A

daptomycin
linezolid
ceftaroline

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41
Q

MRSA/ MRSE

A

methicillin resistant staph aureus/epidermidis

MecA gene: change in PBP in cell membrane of bacteria

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42
Q

VRSA

A

vancomycin resistant staph aureus

genes encode enzymes that substitute D-lactate for D-alanine in peptidoglycan

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43
Q

VISA

A

vancomycin intermediate staph aureus

synthesis of unusually thick cell wall

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44
Q

D-test

A

evaluates inducible clindamycin resistance
plate with erythromycin and clindamycin antibiotic disks 2 cm apart
postive for inducible resistance: D shape
negative: circular and clindamycin can be used

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45
Q

Tx of TSS

A

supportive: extensive fluids, vassopressors (dopamine, NE)
surgical: remove tampon, explore and debride surgical wounds
antibiotics: vancomycin AND clindamycin (suppresses protein synthesis and therefore toxin synthesis: Linezolid also does this)

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46
Q

S. aureus prevention

A

peri-operative cefazolin +/- vancomycin if MRSA is prevalent in area
intranasal mupirocin to reduce colonization
Hibiclens (chlorexidine gluconate) for bathing +/- antibiotcs (doxy, bactrim)
usually 1 week

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47
Q

urease

A

S. epidermidis, saprophyticus

hydrolysis of urea into CO2 and ammonia

48
Q

novobiocin sensitive

A

S. epidermidis

resistant: saprophyticus

49
Q

biofilm

A

S. epidermidis
once introduced into body, foreign materials become coated with host proteins (fibrinogen, fibronectin, etc.) which serve as receptors for staph surface proteins (ADHESINS)
extracellular polysaccharide matrix or slime is produced that encases bacteria and serves as barrier to antibiotic penetration and may interfere with jost defenses

50
Q

S. epidermidis TX

A

MSSE: oxacillin, nafcillin
MRSE: vancomycin
prosthetic valve endocarditis: rifampin or gentamycin
REMOVE device

51
Q

mannitol fermentation

A

staph aureus

52
Q

strep

A

G+ pairs or chains

catalase neg., type of hemolysis distinguishes

53
Q

streptococcus pyogenes

A

Group A strep
skin, oropharynx
pyogenci inflammation, exotoxin, immunologic
M protein, polysaccharide capsule, hyaluronidase, streptokinase, DNase, C5a peptidase, streptococcal chemokine protease, streptolysin O/S, erythrogenic toxin, pyrogenic exotoxin A, extoxin A/B/C
beta hemolytic
bacitracin sensitive
pharyngitis, cellulitis/impetigo/erysipelas, necrotizing fasciitis, TSS, scarlet fever, pueroperal sepsis, endometritis, rheumatic fever, glomerulonephritis

54
Q

streptococcus agalactiae

A

Group B strep
vagina (acquired in urtero), colon
beta hemolytic: narrow
lack of hydrolysis of bile esculin
hydrolyzes hippurate
bacitracin resistant
CAMP test
polysacchride capsule
risk factor: premature rupture of membrane (PROM) in colonized women, babies prior to 37 weeks, children whose mothers lack Ab
neonatal sepsis, meningitis, PNA
adults: invasive infections: septic arthritis, cellulitis, osteomyelitis,
association: DIABETES, BREAST CA
Dx: gram stain, culture, rapid DNA test for vaginal/rectal
Tx: penicillin, ampicillin, vancomycin if PCN allergy
prevention: screen women between 35-37 weeks: IV PCN G/ampicillin at delivery

55
Q

enteroccous faecalis/faecium

A

Group D strep
colon
gamma hemolytic
can grow in hypertonic saline or in bile
low virulence, capsule, enzymes that injure host
hospital acquired UTIs, blood stream infections, endocarditis, intra-abdominal infections
Tx: combination antibiotics required: PCN/Vanc (depends on susceptibility) and aminoglycoside
if vanc resistant (more likely E. faecium): linezolid or daptomycin

56
Q

streptococcus bovis (galaliticus)

A 
Group D strep
gamma hemolytic
ENDOCARDITIS in patients with COLON CA
does not grow in hypertonic saline
Tx: PCN, ceftriaxone, vacomycin
57
Q

Viridian group streptococci

A

alpha hemolytic
mouth, colon
resistant to lysis by bile, optochin resistant
enter blood stream after DENTAL SURGERY in patients with CAVITIES
no enzymes/exotoxins
glycocalyx: attach to heart valve
BRAIN (or liver, abdominal) ABSCESS, ENDOCARDITIS,
includes: sp. anginosus, milleri, intermedius, mutans, sanguis
Tx: depends on susceptibilities, PCN or ceftriaxone
endocarditis Tx with intermediates susceptibility to PCN: add gent

58
Q

peptostreptococcus

A

anaerobe
flora: gut, mouth, vagina
found in mixed anaerobic infections/abscesses: BRAIN, ABDOMEN, PELVIC ABSCESS
Tx: penicillin

59
Q

streptococcus pnuemoniae

A

alpha hemolytic
optochin resistant
lysed by bile

60
Q

Group C and G strep

A

beta hemolysis
streptococcus dysgalactiae subspecies equismilis
flora of URT, asymptomatic colonizer of skin, GI, vagina
emerging cause of human infection: invasive infections, pharyngitis, bacteremia, meningitis, puerperal infections
ACQUIRED VIRULENCE FROM GAS: capsule, superantigen, etc.
rapid tests do not detect GCS/GGS

61
Q

Group A strep

A

streptococcus pyogenes

62
Q

Group B strep

A

streptococcus agalactiae

63
Q

Group D strep

A

enteroccous faecalis/faecium
streptococcus bovis
hydrolyzes esculin in presence of bile
gamma hemolytic

64
Q

M protein

A

GAS
anti-phagocytic
protrudes from outer surface of cell and interferes with ingestion by phagocytes
lots of types

65
Q

polysaccharide capsule

A

GAS
anti-phagocytic
made of hyaluronic acid

66
Q

hyaluronidase

A

GAS
degrades hyaluronic acid
spreading factor in cellulitis and skin infections

67
Q

streptokinase

A

GAS

activates plasminogen to plasmin, dissolves fibrin in clots, thrombi and emboli

68
Q

streptodornase (DNase)

A

GAS
degrades DNA in exudates/necrotic tisse
protect bacteria from being trapped in neutrophils extracellular traps (NETs)

69
Q

C5a peptidase

A

GAS

cleaves C5a: minimizes influx of neutrophils early in infection

70
Q

streptococcal chemokine protease

A

GAS

prevention of migration of neutrophils into site of infection by degrading chemokine IL-8 (neutrophil recruiter)

71
Q

streptolysin O

A

GAS
cytotoxic, protect from phagocytic killing and enhance bacterial influence
HEMOLYSIN
OXYGEN LABILE: beta hemolysis only when colonies grow under surface of blood agar plate
Ab formed

72
Q

streptolysin S

A 
GAS
more modest effect on virulence
HEMOLYSIN
OXYGEN STABLE: causes beta hemolysis on surface of the plate
no Ab formed
73
Q

pharyngitis

A

GAS
Sx: sore throat, inflamed tonsils with pharyngeal exudate, N/V, tender enlarged cervical lymph nodes
ABSENCE of URI Sx
Dx: RAPID STREP antigen TEST (specific, not sensitive), throat culture if neg. rapid test
neg culture: DISCONTINUE antibiotics

74
Q

rapid strep antigen test

A

pharyngitis
detects bacterial antigen in throat swab
antigens react with Ab bound to latex particles
positive: agglutination of latex particles

75
Q

GAS Tx

A 
all 10 days except Z pac
oral PCN V: 2-3x/day 
amoxicillin, cephalexin: 2x/day 
Pen allergy:
azithromycin 2-5 days
clarithromycin, clindamycin: 3x/day
76
Q

complications of untreated GAS pharyngitis

A

immune mediated: rheumatic fever

local extension: otitis media, sinusitis, mastoiditis, meningitis, peritonsillar/retropharyngeal abscess

77
Q

erysipelas

A

GAS
rapidly spreading erythematous cutaneous swelling that may begin in face
sharp well-demarcated, serpiginous border
BUTTERFLY on face

78
Q

cellulitis

A

GAS

dermis and subcutaneous fat infection

79
Q

impetigo

A

GAS

papules progressing to vesicles then pustules that rapidly break down to form adherent crusts with golden appearance

80
Q

necrotizing fasciitis

A

GAS: M protein 1/3, exotoxins A/B/C, trypsinlike protease
infection of deeper tissues, progressive destruction of muscle fascia and overlying subQ fat
infection spreads along muscle fascia due to poor blood supply
Sx: PAIN, erythematous, swollen, warm, shiny, crepitus
acute, rapid progression: skin changes from red-purple to blue-gray
advanced infection: fever, tachycardia, systemic toxicity
associated with: strep TSS
predisposing factors: skin injury, blunt trauma, surgery, IVDU, childbirth
NO NEUTROPHILS

81
Q

trypsinlike protease

A

GAS: necrotizing fasciitis

degrades IL-8: no neutrophil recruitment

82
Q

erythrogenic toxin

A

GAS: scarlet fever

SUPER ANTIGEN responsible for rash

83
Q

pyrogenic exotoxin A

A

GAS: TSS
SUPERANTIGEN
fever inducing

84
Q

superantigen

A

causes large release of cytokines

85
Q

exotoxin B (extracellular cysteine protease)

A

GAS: necrotizing fasciitis

rapidly destroys tissue

86
Q

strep TSS

A

GAS most often
entry: skin, vagina, pharynx
trauma that develops deep infection in 2-3 days: often soft tissue of extremity
Sx: diffuse erythema, fever, chills, myalgia, N/V/D
complications: DIC, AKI, ARDS
Dx: isolate GAS from sterile site
Tx: penicillin plus clindamycin (or linezolid)

87
Q

scarlet fever

A 
GAS
children
erythrogenic toxin
Tx: sore throat, DIFFUSE ERYTHEMA on head and neck spreads to trunk, SAND PAPER SKIN, rash desquamates, STRAWBERRY TONGUE
complication of pharyngitis
88
Q

post-strep glomerulonephritis

A

GAS
poor socioeconomic status
Ag-ab complexes on glomerular basement membrane
complication of SKIN INFECTION, pharyngitis
Sx: HTN, facial, LE edema, DARK URINE, subclinical
most patients recover completely

89
Q

acute rheumatic fever

A

GAS
Ab against GAS proteins cross-react with host antigens: M protein
Jones Criteria: polyarthritis, carditis, nodules, erythema marginatum, Sydenham chorea
2 weeks after untreated pharyngitis or scarlet fever
Dx: ASO titer: STREPTOLYSIN O
Tx: even though infection was weeks ago, full antibiotics
prevent strep infections with Hx of RF: PCN IM monthly for many years

90
Q

lack of hydrolysis of bile esculin agar

A

GBS

does hydrolyze esculin: GDS: black pigment

91
Q

hydrolyzes hippurate

A

GBS

92
Q

bacitracin resistant

A

GBS

sensitive: GAS

93
Q

CAMP test

A

GBS

protein is produced that enhances hemolysis on sheep blood agar when combined with beta-hemolysin of S. aureus

94
Q

grows in hypertonic saline

A

enterococcus faecalis/faecium

NOT: streptococcus bovis (galaliticus)

95
Q

resistant to lysis by bile

A

viridans group strep

lysed by bile: S. pneumo

96
Q

optochin resistant

A

Viridian group strep

sensitive: S. pneumo

97
Q

glycocalyx

A

strep viridans

allow organism to attach to heart valve

98
Q

streptococcus mutans

A

cause of dental carries

synthesizes polysaccharides in dental plaque

99
Q

alpha hemolysis

A

green on blood agar: partial hemolysis

viridans group strep, S. pneumoniae

100
Q

gamma/non-hemolytic

A

GDS: S. bovis and enterococcus

101
Q

native acute infectious arthritis

A

bacterial infection in joint: suppurative/pyogenic/septic arthritis
Sx: intense pain, LIMITED ROM in 1-2 week period, swelling, red, warmth
mycobacterial and fungal are more chronic and slowly progressive
usually MONOARTICULAR: KNEE, hip, shoulder, wrist, ankle
HIP in children most common
Dx: ARTHROCENTESIS REQUIRED; leukocytosis, elevated ESR and CRP
can get X-ray/CT/MRI: early: normal osseous structures, late: joint space loss, bony erosion
ultrasound to guide needle aspiration
Tx: antibiotics, drain +/- irrigation and debridement
SURGICAL EMERGENCY

102
Q

pathophysiology of septic arthritis

A

depends on adherence of organisms to synovial membrane, bacterial proliferation in synovial fluid and host inflammatory response
joint disease/injury: increased exposure of ECM proteins (fibronectin, collagen, elastin, hyaluronic acid) that promote bacterial attachment

103
Q

mycobacterial arthritis

A

MTB
chronic granulomatous mono arthritis (usually homogeneous from lung)
knee, hip, ankle
PPD
Dx: synovial biopsy (granulomas), acid fast stain, PCR
Tx: RIPE for 8 weeks, then INH and RIF for 6 months

104
Q

mycobacterial arthritis risks

A
  1. older than 65
  2. female
  3. immigrant from high TB region
  4. low SE status
  5. incarceration
  6. alcohol abuse
  7. immunosuppressed/HIV
  8. pre-existing joint disease
105
Q

prosthetic joint infection

A

highly susceptible to infection
joint inoculation during Sx or early post operation
S. aureus most common (next coag. neg. staph, strep, GNB, enterococci)
lower leukocyte count than native; neg. culture does not rule out Dx
Tx: remove prosthesis, prolonged antibiotics

106
Q

viral arthritis

A

Rubella, Parvo B19, HCV, HBV
immune complex
Sx: arthralgia or arthritis
most short duration and resolve spontaneously
small joints of hand most common, can get large joints

107
Q

osteomyelitis

A

S. aureus most common (express high affinity adhesins)
infection localized to bone
bone destruction, sequestra (dead bone)
develop from: contagious spread from joint/soft tissue (mono bacterial), hematogenous (polymicrobial), direct inoculation
difficult to treat
Sx: nonspecific pain, draining sinus tract
Dx: MRI/CT (sensitive); X-ray (cheap, not sensitive), elevated ESR and CRP, needle aspiration to identify organism

108
Q

most common organism for osteomyelitis

What if you stepped on a nail?

A

STAPH
others: strep, enterococci, gram neg. (Pseudomonas, E. coli, serratia), anaerobes, MTB
Nail: Pseudomonas
rare: dimorphic fungi, Salmonella, other mycobacteria
Tx: Sx (remove hardware, drain, debride), antibiotics

109
Q

osteomyelitis Tx

A

4-6 weeks IV
most common: beta-lactams, Vancomycin
linezolid (oral): due to AE: limit to VRE and those intolerant to vanc.
daptomycin: G+

110
Q

vertebral osteomyelitis and spondylodiskitis

A

source: skin/ soft tissue infection, GU tract infection, infective endocarditis, IVDU, post-op, hematogenous (most common)
most common: STAPH
endemic regions: MTB, Brucella
Sx: epidural abscess, motor/sensory deficit
Dx: high suspicion in high risk, MRI
Tx: at least 6 weeks antibiotics

111
Q

osteomyelitis in DM or vascular insufficiency

A

FOOT
Dx: MRI
Tx: surgery, broad spectrum antibiotics (zosyn, ertapenem, cephalosporins, flagyl, cipro, other quinolones), revascularization in PVD
risk: DM 10+ yrs, poor glucose control, retinal or renal complicaitons, peripheral neuropathy, callus, PVD

112
Q

acute hematogenous osteomyelitis in children

A

STAPH, STREP
METAPHYSES of long bone (tibia, femur)
neonatal: septic arthritis of adjacent joint; GBS, E. COLI
Dx: clinical, MRI, blood culture
Tx: antibiotics (switch from IV to oral when afebrile) for 3 weeks

113
Q

pathogenesis of acute hematogenous osteomyelitis in children

A

capillary ends of artery make sharp loops under growth plate: slow turbulent blood flow
minor trauma: obstruction of capillaries: avascular necrosis, then seeded from transient bacteremia
capillaries lack phagocytes

114
Q

osteomyelitis in sickle cell disease

A

SALMONELLA, Staph
mostly children
capillary occlusion secondary to skirling may devitalize and infarct gut permitting salmonella invasion
reduced liver and spleen function: can’t clear organisms
bone also devitalized

115
Q

myositis

A

inflammation of muscles
infection uncommon
bacteria, mycobacteria, fungi, virus, parasites
source: contiguous spread, hematogenous

116
Q

pyomyositis

A

acute bacterial infection of skeletal muscle
TROPICS
STAPH AUREUS, then strep
large muscles: lower extremities, turn, shoulder
Sx: fever, localized muscle pain, stiff/swell/tender, pus accumulation
previous bacteremia along with minor muscle injury
Dx: imaging: MRI best
Tx: drain ABSCESS, vancomycin
if not Dx: sepsis, striking erythema, very tender, fluctuance

117
Q

risk factors for pyomyositis

A
  1. HIV
  2. IVDU
  3. alcoholic liver disease
  4. corticosteroids
  5. hematologic malignancy
    rare: post partum, post abortion, post op

Musculoskeletal (13 decks)

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