Micro: Cross Flashcards
(117 cards)
1
Q
Tx of septic arthritis
- gram pos. cocci
- GNR
- neg. gram stain
A
- vancomycin
- cephalosporin or zosyn (piperacillin-tazobactam)
- vancomycin plus cephalosporin
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
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
4
Q
Most common source of infection in septic arthritis
A
HEMATOGENOUSLY
other: direct inoculation (trauma, Sx, bite, percutaneous), spread from soft tissue
5
Q
gram neg. bacilli for septic arthritis
- IVDU, iatrogenic (SURGERY or INTRA-ARTICULAR injection)
- young adults, late complement deficiency
- sickle cell and SLE
- cat or dog bite
- unpasteurized
- RA
A
at risk: elderly, immunocompromised, neonates, IVDU
- P. aeruginosa (staph aureus also common in IVDU)
- Neisseria gonorrhea, Neisseria meningitidis
- Salmonella
- Pasteurella multocida
- Brucella
- staph aureus most common
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
7
Q
alpha toxin (lecithinase)
A
C. perfringens traumatized tissue (especially muscle) damage cell membranes including RBCs produce GAS in tissue HEMOLYSIS: anemia
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
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
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
11
Q
Osteomyelitis in IVDU
A
S. aureus (MRSA) and Pseudomonas
also: Candida
unusual sites of infection are common: sternoclavicular, sternochondral joint, pubic symphysis
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
13
Q
staphylococci
A
G+ cocci in grapelike clusters
catalase
14
Q
catalase
A
STAPH
degrade H202: limits neutrophil ability to kill
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
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
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
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
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
20
Q
beta hemolysis
A
complete lysis of RBC on blood agar
staph aureus
GAS, GBS, GCS/GGS
21
Q
mannitol fermentation
A
staph aureus
22
Q
beta lactamase
A
degrades penicillin
staph aureus
23
Q
mecA gene
A
staph aureus: MRSA
encodes altered penicillin binding proteins in beta-lactamase-resistant penicillins (methicillin)
24
Q
staphyloxanthin
A
staph aureus
carotenoid: causes golden color to colonies
inactivates microbicidal effect of SUPEROXIDES and other ROS in neutrophils
25
hemolysins
staph aureus
| hemolyze RBC to use iron for growth
26
peptidoglycan
staph aureus
stimulates macrophages to produce cytokines, activates complement/coagulation cascades
SEPTIC SHOCK without endotoxin
27
protein A
staph aureus
cell wall protein
binds Fc (complement binding site) of IgG and prevents complement activation
NO C3b produced: reduced phagocytosis
28
teichoic acid
staph aureus
mediate adherence of staph to mucosal cells
lipoteichoic acid induces IL-1 and TNF from macrophages
29
polysaccharide capsule
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
30
alpha toxin/hemolysin
staph aureus
membrane-damaging hemolytic toxin
forms holes in host cells
causes necrosis of skin and hemolysis
31
panton valentine (P-V) leukocidin
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
32
gamma-toxin/leukotoxin
staph aureus
membrane-damaging hemolytic toxin
lyses phagocytes and RBC
33
scalded skin syndrome
```
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
```
34
exfoliatin/exfoliative toxins A and B
staph aureus: scalded skin syndrome, bullous impetigo
| protease that cleaves desmoglein in desmosomes leading to separation of epidermis at the granular cell layer
35
enterotoxin 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
36
bullous impetigo
```
staph aureus
EXFOLIATIVE TOXIN: localized
vesicles flaccid bull with clear yellow fluid, later darker and more turbid
ruptured bull leave thin brown crust
TRUNK
```
37
staph toxic shock syndrome
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
38
Tx of MSSA
nafcillin/oxacillin, cephalosporins (cefazolin, ceftriaxone, cefepime, ceftaroline)
vancomycin
augmentin (mild infections)
resistant to PCN (produce beta lactamase)
39
Tx of MRSA
vancomycin, daptomycin
linezolid
ceftaroline
mild: bactrim, clindamycin, doxycycline
40
Tx VISA/VRSA
daptomycin
linezolid
ceftaroline
41
MRSA/ MRSE
methicillin resistant staph aureus/epidermidis
| MecA gene: change in PBP in cell membrane of bacteria
42
VRSA
vancomycin resistant staph aureus
| genes encode enzymes that substitute D-lactate for D-alanine in peptidoglycan
43
VISA
vancomycin intermediate staph aureus
| synthesis of unusually thick cell wall
44
D-test
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
45
Tx of TSS
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)
46
S. aureus prevention
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
47
urease
S. epidermidis, saprophyticus
| hydrolysis of urea into CO2 and ammonia
48
novobiocin sensitive
S. epidermidis
| resistant: saprophyticus
49
biofilm
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
S. epidermidis TX
MSSE: oxacillin, nafcillin
MRSE: vancomycin
prosthetic valve endocarditis: rifampin or gentamycin
REMOVE device
51
mannitol fermentation
staph aureus
52
strep
G+ pairs or chains
| catalase neg., type of hemolysis distinguishes
53
streptococcus pyogenes
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
streptococcus agalactiae
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
enteroccous faecalis/faecium
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
streptococcus bovis (galaliticus)
```
Group D strep
gamma hemolytic
ENDOCARDITIS in patients with COLON CA
does not grow in hypertonic saline
Tx: PCN, ceftriaxone, vacomycin
```
57
Viridian group streptococci
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
peptostreptococcus
anaerobe
flora: gut, mouth, vagina
found in mixed anaerobic infections/abscesses: BRAIN, ABDOMEN, PELVIC ABSCESS
Tx: penicillin
59
streptococcus pnuemoniae
alpha hemolytic
optochin resistant
lysed by bile
60
Group C and G strep
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
Group A strep
streptococcus pyogenes
62
Group B strep
streptococcus agalactiae
63
Group D strep
enteroccous faecalis/faecium
streptococcus bovis
hydrolyzes esculin in presence of bile
gamma hemolytic
64
M protein
GAS
anti-phagocytic
protrudes from outer surface of cell and interferes with ingestion by phagocytes
lots of types
65
polysaccharide capsule
GAS
anti-phagocytic
made of hyaluronic acid
66
hyaluronidase
GAS
degrades hyaluronic acid
spreading factor in cellulitis and skin infections
67
streptokinase
GAS
| activates plasminogen to plasmin, dissolves fibrin in clots, thrombi and emboli
68
streptodornase (DNase)
GAS
degrades DNA in exudates/necrotic tisse
protect bacteria from being trapped in neutrophils extracellular traps (NETs)
69
C5a peptidase
GAS
| cleaves C5a: minimizes influx of neutrophils early in infection
70
streptococcal chemokine protease
GAS
| prevention of migration of neutrophils into site of infection by degrading chemokine IL-8 (neutrophil recruiter)
71
streptolysin O
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
streptolysin S
```
GAS
more modest effect on virulence
HEMOLYSIN
OXYGEN STABLE: causes beta hemolysis on surface of the plate
no Ab formed
```
73
pharyngitis
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
rapid strep antigen test
pharyngitis
detects bacterial antigen in throat swab
antigens react with Ab bound to latex particles
positive: agglutination of latex particles
75
GAS Tx
```
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
complications of untreated GAS pharyngitis
immune mediated: rheumatic fever
| local extension: otitis media, sinusitis, mastoiditis, meningitis, peritonsillar/retropharyngeal abscess
77
erysipelas
GAS
rapidly spreading erythematous cutaneous swelling that may begin in face
sharp well-demarcated, serpiginous border
BUTTERFLY on face
78
cellulitis
GAS
| dermis and subcutaneous fat infection
79
impetigo
GAS
| papules progressing to vesicles then pustules that rapidly break down to form adherent crusts with golden appearance
80
necrotizing fasciitis
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
trypsinlike protease
GAS: necrotizing fasciitis
| degrades IL-8: no neutrophil recruitment
82
erythrogenic toxin
GAS: scarlet fever
| SUPER ANTIGEN responsible for rash
83
pyrogenic exotoxin A
GAS: TSS
SUPERANTIGEN
fever inducing
84
superantigen
causes large release of cytokines
85
exotoxin B (extracellular cysteine protease)
GAS: necrotizing fasciitis
| rapidly destroys tissue
86
strep TSS
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
scarlet fever
```
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
post-strep glomerulonephritis
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
acute rheumatic fever
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
lack of hydrolysis of bile esculin agar
GBS
| does hydrolyze esculin: GDS: black pigment
91
hydrolyzes hippurate
GBS
92
bacitracin resistant
GBS
| sensitive: GAS
93
CAMP test
GBS
| protein is produced that enhances hemolysis on sheep blood agar when combined with beta-hemolysin of S. aureus
94
grows in hypertonic saline
enterococcus faecalis/faecium
| NOT: streptococcus bovis (galaliticus)
95
resistant to lysis by bile
viridans group strep
| lysed by bile: S. pneumo
96
optochin resistant
Viridian group strep
| sensitive: S. pneumo
97
glycocalyx
strep viridans
| allow organism to attach to heart valve
98
streptococcus mutans
cause of dental carries
| synthesizes polysaccharides in dental plaque
99
alpha hemolysis
green on blood agar: partial hemolysis
| viridans group strep, S. pneumoniae
100
gamma/non-hemolytic
GDS: S. bovis and enterococcus
101
native acute infectious arthritis
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
pathophysiology of septic arthritis
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
mycobacterial arthritis
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
mycobacterial arthritis risks
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
prosthetic joint infection
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
viral arthritis
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
osteomyelitis
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
most common organism for osteomyelitis
| What if you stepped on a nail?
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
osteomyelitis Tx
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
vertebral osteomyelitis and spondylodiskitis
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
osteomyelitis in DM or vascular insufficiency
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
acute hematogenous osteomyelitis in children
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
pathogenesis of acute hematogenous osteomyelitis in children
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
osteomyelitis in sickle cell disease
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
myositis
inflammation of muscles
infection uncommon
bacteria, mycobacteria, fungi, virus, parasites
source: contiguous spread, hematogenous
116
pyomyositis
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
risk factors for pyomyositis
1. HIV
2. IVDU
3. alcoholic liver disease
4. corticosteroids
5. hematologic malignancy
rare: post partum, post abortion, post op
