SSTs (4) Flashcards
list the SST/joint infections we are expected to know
- animal bites
- infectious lymphadenitis
- septic arthritis
- disseminated gonococcal infection
- deep space infections (Ludwig’s angina)
- superficial skin infections (impetigo, scalded skin)
- diabetic foot
- cellulitis/erisypelas
- necrotizing fasciitis
- osteomyelitis
what % of cat bites get infected
80%
what is the etiologic agent most common in infected cat bites
Pasteurella multocida
what type of infections result from cat bites
deep space
bone
joint
these types are more likely with cat bites
Tx for cat bites
empiric = amoxicillin-clavulanate
what % of dog bites get infected
5%
what is the etiologic agent in infected dog bites
Pasteurella canis
Tx for infected dog bites
treat only if bite is severe or pts is immunocompromised
amoxicillin-clavulanate
what is the etiologic agent in cat scratch disease
Bartonella henselae
cats are natural reservoir
what is the etiologic agent in infected human bites
polymicrobial
- STREP VIRIDANS (100%)
- bacteroides (82%)
- S. epidermis (53%)
- corynebacterium
- S. aureus
- Peptostreptococcus
- Eikenella
what is “clenched fist injury”
“reverse bite”
very high risk of infection
risk of septic joint and osteomyelitis
administer IV Ab and imaging
Tx for human bite infections
either amoxicillin-clavulanate or pipercillin-tazobacter (because has coverage for pseudomonas)
what two other diseases should you consider in a patient with a bite wound
tetanus
rabies (i.e bats)
what is another name for infectious lymphadenitis
cat scratch disease
Bartonella henselae
clinical presentation of cat scratch disease/infectious lymphadenitis
local lymphadenitis with or without cutaneous lesion
skin lesion shows several days after exposure and lasts 1-3 weeks
10% = atypical–> liver, spleen, ocular, neuro, MSK, FUO involvement
Tx for cat scratch disease
azithromycin
other than cat scratch disease, other etiologies of infectious lymphadenitis
- GAS
- S. aureus
- toxoplasma
- viral: HIV, CMV, EBV
- mycobacteria
- sporotrichosis, histoplasma, francisella, bacillus anthracis, borellia burgdorferi, yersenia pestis, hocardia
risk factors for septic arthritis
- older than 80
- diabetes
- pre-existing joint disease
- recent joint surgery or infection
- prosthetic joint
- IVDU
etiologic agents in septic arthritis
S. AUREUS
S. aureus»strep>gram -orgs/TB/fungal
how do you diagnose septic arthritis
arthrocentesis (synovial fluid analysis)
gram stain/culture
blood culture
xray to rule out osteomyelitis
if septic arthritis is due to S. aureus, how is it treated
remove joint
what is disseminated gonoccoccal infection
a type of septic arthritis
clinical presentation of disseminated gonococcal infection
2 classic syndromes
- triad of tenosynovitis, polyarthritis and dermatitis
- purulent arthritis
Tx of disseminated gonococcal infection
ceftriaxone and doxycycline
doxy covers chlamydia (most people need both)
if purulent arthritis, IV therapy with joint aspiration
where do deep space infections arise from
progression of an oral infection
what is Ludwig’s angina
deep space infection
cellulitis of bilateral sublingual/submandibular spaces
risk factors for Ludwig’s angina
- immune compromised
- tongue piercing
- mandibular fracture
almost always results from oral infection (2nd and 3rd molars are most common)
etiologic agents for Ludwig’s angina
strep and anaerobes (gram +)
can also be bacteroides
clinical presentation of deep space infection/Ludwig’s angina
swollen neck
difficulty opening mouth, swallowing
fever and malaise
Tx for deep space infections
monitor and protect airway (1/3 patients require intubation)
antibiotics: penicillin G OR clindamycin + metronidazole
surgical evaluation
CT to assess size and spread
what type of infections are superficial skin infections
toxin mediated skin damage
etiological agent for scalded skin syndrome
S. aureus
classical presentation of scalded skin syndrome
NIKOLSKYS SIGN
reddened skin
fluid collects underneath
skin rubs off leaving red base
diagnosis of scalded skin syndrome
clinical
Tx scalded skin syndrome
symptomatic
usually vancomycin if need Abs
2 types of impetigo
bullous
non-bullous
which type of impetigo is highly contagious and is seen in school aged kids?
which type is seen in neonates?
non bullous = highly infectious and seen in school aged kids
bullous = seen often in neonates
etiologic agent of non bullous impetigo
S. aureus
also GAS
etiologic agent of bullous impetigo
TOXIN producing S. aureus
exfoliative toxin A and B
diagnosis of impetigo
clinical
for bullous may have cultures, septic eval
Tx nonbullous impetigo
topical antibiotic–MUPIROCIN
PO–cloxacillin
cephalosporins
Tx bullous impetigo
oral or IV Ab
cloxacillin
cephalosporin
vancomycin is MRSA suspected
what type of infection is diabetic foot
peripheral vascular disease related soft tissue infection
diabetic food risk factors
previous amputation wound extending to bone peripheral vascular disease ulcer duration > 30 days loss of sensation Hx of recurring ulcers wound caused by trauma
40% of infected people have peripheral vascular disease
etiologic agents in 1. mild 2. moderate 3. severe diabetic foot
- S. aureus (MSSA), streptococcus
- S. aureus (MSSA), streptococcus
- assume everything
how do you assess diabetic foot
“assess at 3 levels”
- whole patients–>signs of systemic illness, social support
- affected limb/foot–> problems impairing healing, peripheral vascular disease
- infection–> is an infection present? how severe? hospitalize all patients with a severe infection or moderate infection with low social support or failing outpatient management
surgery consult if suspect deep space infection or necrotizing fasciitis
how do you correctly culture a diabetic foot infection
- clean and debride the wound
- scrape or biopsy the ulcer base
- aspirate purulent secretions –> never swab an uninfected wound or a dirty infected wound
- send for gram stain, aerobic and anaerobic culture
Tx for diabetic foot infection
majority of mild and moderate cases can be treated with Abs that cover staph and strep
ALL infected wounds should have Abs
CLOXACILLIN (choice) or 1st generaton cephalosporin
if you think high risk for MRSA give empiric MRSA coverage
what is cellulitis
infection of the deep dermis and subcutaneous fat
how does cellulitis happen
break in skin allowing normal skin flora or exogenous flora to invade dermis and subcutaneous tissue
epidemiology of cellulitis
diabetics
peripheral vascular disease
etiologic agent of cellulitis
almost always strep or staph
clinical presentation of cellulitis
simple, localized cellulitis–> no fever/other systemic symptoms; WBC normal; lymphademopathy and lymphangitis
severe cellulitis–> systemic symptoms, bullae, hemorrhage, severe swelling
how do you monitor the progression of suspected cellulitis
infection spreads rapidly… draw a line around the infected area’s borders to monitor spread
Tx for cellulitis
empiric Abs
elevate
analgesics
what is erisypelas
infection limited to upper dermis and superficial lymphatics
what causes erisypelas
almost always B hemolytic strep (i.e GAS/S pyogenes)
clinical presentation of erisypelas
sharp, raised, well demarcated edema
rapid onset
fever and signs of systemic toxicity
Tx of erisypelas
mild/moderate = outpatient –> penicillin or amoxicillin
severe = admit to hospital –> IV benzathine penicillin G
what type of infection is necrotizing fasciitis
rapidly progressive soft tissue infection
where does necrotizing fasciitis infect
deep infection of the subcutaneous tissue causing severe destruction of fat and fascia
etiologic agent of
1. type 1
2. type 2
necrotizing fasciitis
- immunocompromised or post operation patients–> POLYMICROBIAL
- healthy individuals of any age –> GROUP A STREP (GAS) aka Beta hemolytic strep
clinical presentation of necrotizing fasciitis
Skin: bullae disproportionate pain swelling erythema crepitus (gangrene)
systemic:
fever
tachycardia
hypotension
how do you test for necrotizing fasciitis
deep tissue cultures during debridement
Tx of necrotizing fasciitis
IMMEDIATE SURGICAL CONSULT
IV Abs–>
Type 1: piperacillin-tazobactam and metronidazole -OR- clindamycin
(also carbapenems + vanco?) (for polymicrobial)
Type 2: clindamycin and penicillin G (for GAS)
what is osteomyelitis
inflammation or infection of the bone or bone marrow
what causes osteomyelitis
depends on the route of infection and patients characteristics
IVDU in vancouver–> S. aureus (MRSA)
otherwise if its spinal osteomyelitis its likely TB
how do you diagnose osteomyelitis
CT
Tx for osteomyelitis
- for IVDU–> debridement and bone culture in the OR; Ab = VANCO (+ screen for endocarditis)
- for spinal osteomyelitis (due to TB)–> TB TX for 12 months
what do all bite injuries need to be assessed for
tetanus and rabies risk
septic arthritis is _____ spread and the most common organism is _____
hematogenously
S. aureus
what is the most reliable way to test for disseminated gonococcal infection
cervical or urethral swab
what organism do cat and dog bites usually contain? what should they be treated with?
pasteurella
amoxicillin-clavulanate
what SST infection is a surgical emergency
necrotizing fasciitis
non-bullous impetigo is usually caused by ____ and can be treated with _____
S. aureus
topical or oral Abs
bullous impetigo is usually caused by ____ and can be especially severe in _____
S. aureus TOXIN
neonates
what increases the risk of infection in diabetics
- impaired sensation
- impaired healing
- frequent peripheral vascular disease
