Microbiology-Bites Flashcards
Most common cause of animal bites
Dogs
Animal bites with higher risk of infection than dog bites
Cats, deeper penetration w/deeper infection and osteomyelitis
Common microbial infections associated with cat and dog bites
Pasteurella, capnocytophagia, normal skin flora and anaerobes
What people are at higher risk for infection by capnocytophagia after a dog/cat bite? What symptoms are common? How do you treat?
Immunocompromised. Presents with fever, muscle aches and rare sepsis. Tx with augmentin, avoid bactrim and aminoglycosides.
Symptoms that commonly present with pasteurella infection after a cat/dog bite? How do you treat?
Fever, cellulitis, arthritis, pneumonia, endocarditis, meningitis 15 hours after bite. Tx with augmentin or azithromycin. Avoid erythromycin and clindamycin.
More common microbe involved in community acquired MRSA from animals
S. intermedius > S. aureus.
Indications for antibiotic prophylaxis after bits
Deep bites (cats), crush injuries, venous/lymphatic compromise, wounds close to bone, wounds that requires surgical care, immunocompromised. Drug of choice = augmentin.
28 year old pregnant woman presents with a red and swollen cat bite. She has a penicillin allergy. What is appropriate empiric therapy?
Axithromycin
Cat-scratch disease
Bartonella henselae (mostly in fall/winter in outdoor cats and affects younger kids)
Cat scratch symptoms
Papule/pustule at site of infection, fever, enlarged lymph nodes 1-3 weeks after exposure.
Diagnosing and treating cat-scratch disease.
Dx clinically most of the time, can also use serology or PCR. Tx with azithromycin if symptoms do not resolve spontaneously (they usually do).
Common pathogens associated with human bites
Staph, strep, eikenella (facultative). Also worry about HSV, HIV, HepC and HepB.
A 52 year old man suffers a hand injury in a brawl from punching a guy in the face. He has bony fragments on x-ray. He was given cephalexin in the ER and sent home. 5 days later he returns tachycardic, hypotensive, feverish and confused. His hand is warm, edematous, painful to move and has decreased sensation. He was given Tdap shot, started on amp-sulbactam and has a fasciotomy for compartment syndrome. Gram stain shows an anaerobic gram negative bacilli. How do you treat him?
Eikenella corrodens is a common infection in human “bites”. It is resistant to cephalexin, clindamycin, erythromycin and metronidazole. Tx with augmentin, fluoroquinolones, TMP-SMX or doxycycline.
Common pathogens in pig bites? How do you treat them?
Strep, staph, pasteurella, actinobacillus, tx with augmentin + ciprofloxacin to cover actinobacillus.
Symptoms and pathogens associated with rat-bite fever?
Streptobacillus moniliformis (US, branching gram-negative bacillus shown below), spirillum minus (asia). Symptoms: fever, pustular rash (shown below), migratory polyarthritis and endocarditis. Tx with augmentin or doxycycline.
Pathogen associated with seal finger? Symptoms? Treatment?
Mycoplasma. Papular lesion with pain, swelling and joint involvement. Tx with tetracycline.
Pathogens associated with the candiru fish (cat fish in amazon river attracted to urea)?
They swim up your urethra and lodge there to get urea waste.
Bacterial infections associated with snake bites
Secondary flora wounds are rare because venom is sterile.
Things to not do when bit by a snake? What should you do?
Suck out the venom, apply a tourniquet, place ice packs. You should give anti-venom, first aid and ceftriaxone + clavulanate empirically.
Pathogens associated with monkey bites
Staph, strep, eikenella, Herpes B virus
Symptoms associated with herpes B virus after a monkey bite?
Reactivation, vesicular lesions, paresthesias, seizures, respiratory failure. (80% fatality rate)
Tx for person exposed to herpes B virus after a monkey bite
Prophylactic acyclovir if pregnant, valacyclovir for others (can be life-long). IV if CNS involved.
3 phases of rabies
1) Flu-like illness, prickling at bite site 2) Agitation, delirium 3) Coma death
Diagnosing rabies
1) Salive PCR 2) Neck biopsy (nerves) 3) Serum immunoassay 4) CSF immunoassay
Animal bites that merit immediate rabies prophylaxis
Skunks, raccoons, foxes and bats. Give RIG if not previously vaccinated. Revaccinate if previously vaccinated, don’t give RIG if previously vaccinated.
Path of infection by clostridium tetani?
Spores enter wound, germinate and make toxin that causes muscular spasms and seizures.
Tx for tetanus
TIG, toxoid booster, antibiotics (penicillins or metronidazole). Give prophylaxis TIG and toxoid vaccine if immunization hx is unclear. Don’t give TIG if immunizations are clear and current.
