SSTI, BJ IDBR Flashcards
What are the two major mechanisms by which osteomyelitis occurs?
Continugous Innoculation = contaminate bone directly through ulcer adjacent to bone, the integrity of cortex breached. Seen in DFI, open fractures, surgical procedures. (2) Hematogenous seeding - common for acute long bone osteomyelitis in children, and vertebral osteomyelitis in adults. Site of infection elsewhere.
TX of staphylococcal prosthetic joint infection?
2-6 weeks of pathogen-specific IV therapy + rifampin 300-450 BID followed by rifampin + oral drug for total 3 months.
If TKA - 6 months. Oral companion drug include FQ.
Common organism associated with contiguous-focus osteomyelitis?
Polymicrobial, but most common is staph aureus
most common pathogen associated with open fracture oseomyelitis?
Staph aureus, CoNs, aerobic GNB
what test has the highest PPV for osteomyelitis?
Probe to bone test
what should you know about plan radiographs for osteomyelitis?
abnormalities may not be apparent up to 2 weeks in most types of osteomyelitis
what should you know about technetium Tc99m methylene diphosphonate bone scan for osteomyelitis?
Low specificity patiuclarlay with other bone diseases like neuropathic bone disease or radiation necrosis
which is the best diagnostic test outside of probe to bone/biopsy for orthopedic hardware?
CT/MRI may be degraded. Gallium Ga 67 citrate especially for diskitis, and when MRI cannot be used
what is gold standard for osteomyelitis?
deep bone culture/bone biopsy
when does broad spectrum empirical therapy need to precede surgical therapy?
Concomitant soft tissue infection, sepsis syndrome with osteomyelitis,
the general idea of treatment for chronic osteomyelitis after debridement and removal of orthopedic hardware?
IV/highly bioactive PO for 4-6 weeks with success rates around 80%
the general idea of treatment duration for acute hematogenous cases with vertebral osteomyelitis?
4-6 weeks
Options when orthopedic hardware cannot be removed at time of surgical debridement owing to need to stabilize fracture?
(1) IV therapy, with long term PO suppressive therapy. (2) FQ+rifampin after IV therapy w/o suppressive therapy (studied with staphyloccal infection of fracture fixation device)
Tx of relapse of infection with retained hardware?
remove orthopedic hardware and administer IV/PO for 4-6 weeks
general principles of treatment for chronic osteomyelitis?
source control via debridement/removal of hardware, management of dead space and adequate soft tissue coverage via flaps/grafts/antimicrobial beads, assess vascular supply
Antibiotic duration for DFI?
Parenteral therapy for moderate/severe. PO for low severity. 1-2 weeks for mild, 2-3 for moderate/severe.
what imaging studies used for DFI?
all patients with new DFI have plain radiographs. MRI if soft tissue abscess/osteomyelitis, If MRI contraindicated, radionuclide bon scan and labeled white blood cell scan.
How long would you treat for DFI after radical resection?
If no remaining infected tissue, 2-5 days. if persistent infected/necrotic bone, >4 weeks. (weak/low)
what are risk factors for pseudomonas infection?
high local prevalence, warm climate, drugs, frequent exposure of foot to water
what is a two stage exchange arthroplasty? problem?
implants removed, infected tissues debrided, temporary antibiotic impregnated space placed (stage 1). After weeks of IV antibiotics, reimplantation (stage 2). Between stages 1 and 2, risk of abx toxicity and pain due to lack of functioning joint
what is a one stage exchange arthroplasty?
infected prosthesis removed, infected tissues debrided, and new prosthesis implanted during the same procedure
most common organism in infectious arthritis?
staph aureus
most common organisms after manipulation of joint after surgery?
coagulase negative staphylococci
most common pathogen infectious arthritis in young patients?
neisseria gonorrhoeae
what patient population do you suspect infections due to gram negative bacteremia?
more common in elderly
hardware associated microorganisms?
CoNs, cutibacterium (propionic)
clinical clues to HACEK?
human bite wounds (eikenella corrodens), recent dental procedure or infection
clinical clues ot Kingella Kingae?
this is the K in hacek. children<4 years old
clinical clues to pasturella?
cat or dog bite
clinical clues to salmonella?
sickle cell, diabetes, developing world, unsafe food hygiene, reptile exposure +/- antecedent GI illness
clinical clue to brucella?
consumption of unpasteruzied dairy, travel to endemia area (latin america, meditarranean, middle east), sacroillitis and sponylodiscitis
clinical clue to streptobacillus moniformis?
rat bite
septic arthritis with negative culture or delayed positivity?
gonococcus, HACEK, lyme or mycoplasma
Tx of brucella?
doxycycline + streptomycin or doxycycline + rifampin for at least 12 weeks
brucella clinical features?
ingestion of unpasteruzed diary (goat, cattle sheep) and contact with infected animals. See prodromal nonspecific febrile illnss with sweats
dx approach to pyogenic vertebral osteomyelitis?
- Blood cultures (if staph aureus or lugdunensis - no further workup needed). 2. brucella serologies, PPD/IGRA in appropriate setting 3. percutaneous bone bopsy (paraspinal or bone/disc space). If possible, hold abx for 1-2 weeks.
what is brodie’s abscess?
subacute hematogenous osteomyelitis where bacteria deposit in medullary canal of metaphyseal bone which become surrounded by rim of sclerotic bone–>intraosseous abscess. See a penumbra sign on MRI
define early surgical site infection timing?
<3 months with acute onset of fever, joint pain, swelling. Think Staph aureus
define delayed/subacute infection?
3-24 months of insidious onset of pane. Thinks CoNs or cutibacterium
dfine late acute infection?
> 2 years of acute onset of fever, joint pain, swelling. THink hematenous seding, virulent organisms (staph aureus, strep)
what is the most common pathogen after cat bite?
Pasteurella Multocida
what is the microbiological characteristics for pasteurella?
small aerobic gram negative bacillus
what 6 pathogens that can cause infection after cat bite?
pasteurella, anaerobic bacteria (Fusobacteria), bartonella henselae, rabies virus, S.aureus, Streptococal
what commonly prescribed abx is sensitive and what is resistant to pasteurella?
amoxicillin sensitive, keflex resistant
what are potential pathogens to dog bites?
dog’s mouth: pasteurella canis, capnocytophaga canimorsus. Human skin: s.aureus, s.pyogenes
Typical resistance and sensitivity profiles to pasturella species?
CCDE - cephalexin, clindamycin, dicloxacillin, and often erythromycin resistant. penicillin, doxycycline, bactrim, and extended spectrum cephalosporins sensitive.
Typical resistance/sensitivity profiles to capnocytophaga?
susceptible to augmentin, penicillin, and clindamycin. Resistant to bactrim, and maybe vancomycin
post-exposure prophylaxis is indicated in wounds with which animals?
coyotes, foxes, catle
rat bite fever is caused by which organisms and which vector?
usa is streptobacillus moniliformis. in asia, spirillium minus. From bites or contaminated food or water.
Tx of rat bite fever?
penicillin or doxycycline
symptoms of rat bite fever in the uS?
fever, macular/papular pustular petechial rash and symmetrical polyarthralgia
Describe microbiological features of Eikenella Corrodens?
anaerobic gram negative bacilli
what is the susceptibility profile to Eikenella?
suscepitble to penicillin, FQ, bactrim, doxy, and extended spectrum cephalosporins.
what is the resistance profile to eikenella?
resistant to keflex, clindamycin, erythromycin, and metronidazole
Ddx of organisms causing superficial folliculitis?
S.aureus, Pseudomonas aeruginosa, candida albicans, M.Furfur, Eosinopphilic pustular folliculitis
what is erysipelas?
nonpurulent acute onset of painful rapidly spreading red plaque of inflammation involving epidermis, dermis and subcutaenous layers
what abx should you avoid in treatment of erysipelas?
avoid macroliedes and bactrim
what are elements of staph TSS?
staph has no focal pain, rare tissue necrosis, common erythoderma, very rare bacteremia with low mortality associated with tampons/surgery.
what are elements of strep TSS?
cuts, burns, varicella with focal pain, tissue necrosis, bacteremia, less erythoderma, with high mortality
organisms whose growth is stimulated by excess iron?
VELARY: vibrio vulnificus, E.Coli, Listeria monocytogenes, Aeromonas hydrophilia, Rhizopus (mucor), Yersinia enterocolitica
Leeches
aeromonas
cutaneous anthrax
painless edematous ulcerated papule; woolsorter
Erythrasma due to C.Minutissimum
intertriginous infection and coral red with UV light (woods lamp)
M.Fortuitum, M.chelonae association
nail salon, whirlpool, tattoo parlor
