Infectious Disease Flashcards
Fever of Unknown Origin (FUO): criteria
- Fever >38.3 C (100.9 F)
- 3 + weeks
- No other diagnosis for 3 outpatient visits (or 3 days in the hospital)
FUO: common etiologies (3)
- Infection
- Malignancy
- Connective tissue disease
FUO: name 3 less common infectious reasons
- Intra-abdominal abscesses
- Osteomyelitis
- Tuberculosis
FUO: name 4 malignancies
- Hepatocellular carcinoma
- Leukemia
- Lymphoma (NHL)
- Renal cell carcinoma
FUO: systemic inflamatory causes
- Giant cell arteritis
- Polyarteritis nodosa
FUO: management
- Refer to infectious disease
- Consider admission
Staphylococcal infection
- Nose (main site of colonization)
- 3 major species (Staph aureus, Staph epidermitis, Staph saprophyticus)
- Coagulase postive (staph aureus)
- Beta-hemolytic
Staphylococcus epidermitis
- coagulase negative
- frequent skin contaminant on blood cultures
- LOVES to grow on catheters, IV lines, prosthetic joints
Staphylococcus saprophyticus
- coagulase negative
- Leading UTI cause
- lives in female genital tract
Toxic Shock syndrome
- Staph aureus
- “super antigens”
- abrupt high fever, vomiting, watery diarrhea, rash, conjunctivitis, desquamation of the palms and soles*
Toxic Shock syndrome: Empiric Treatment
Clindamycin + Vancomycin
Staph Scalded Skin Syndrome (SSSS)
- affects neonates 3-15 days old
- loss of cell-to-cell adhesions leading to intra-epidermal splitting
- erythematous patches with large superficial fragile blisters**
- Nikolsky sign*
Staph Scalded Skin Syndrome: treatment
Penicillin-ase resistant beta-lactam
if no response –>Vancomycin
What causes anthrax?
Bacillus anthracis
- gram-positive rod
- spores
- GI tract, skin, inhalation*, direct injection
Most common form of anthrax
cutaneous
- small, painless, pruritic papules that turn into vesicles/bulla –>leave painless necrotic ulcer with black, depressed eschar**
- Edema + lymphadenopathy
Anthrax inhalation clinical course
- spores phagocytosed and transported to mediastinal lymph nodes
- Spores germinate and release toxins
- Toxins cause hemorrhagic necrosis of thoracic lymph nodes (hemoptysis)
- Fulminant is fatal (usually)
Anthrax: CXR
Widened mediastinum (opacity around the hilar lymph nodes)**
How do you test for anthrax?
Report to public health/Send em to CDC!
culture, immunohistochemical staining, molecular testing ex. ELISA, lumbar puncture if concerned for meningitis
How many samples need to be taken from a cutaneous anthrax lesion?
2
- Swab for gram stain
- Swab for PCR
Anthrax: cutaneous treatment
Ciprofloxacin/Levofloxacin
or doxycycline
Treatment for people exposed to aerosolized Bacillus anthracis
- Ciprofloxacin
- start within 48 hours
- 60 days of treatment - Anthrax vaccine (3 dose)
Rabies: cause
rhabdovirus (RNA virus)
- travels along nerves to brain
- multiplies in brain
- travels along efferent nerves to salivary glands
Rabies: clinical presentation
- Pain/parethesias radiating proximally
- Percussion myoedema (mounding of the muscle at percussion site)
- CNS
- “furious” - encephalitic (80%)
- “dumb” - paralytic (20%), kinda like guillan-barre
Rabies: Treatment
- Immuneglobulin
- Rabies vaccine
Zika: cause
flavivirus (arthropod–borne virus)
Zika transmission
- Aedes mosquito
- Sexual transmission
- Vertical transmission
- Blood product transfusion/organ transplant
Zika diagnostics
Viral RNA or IgM
PCR blood or urine
When do you test asymptomatic pregnant women for zika
-Look for IgM 2-12 weeks after they travel to endemic area
or
sexual contact with person with confirmed zika infection
Zika virus: monitoring of pregnancy
US every 3-4 weeks (congenital microcephaly)
complications: meningoencephalitis!
Legionella: etiology
Legionella pneumophila
gram-negative bacilli
Water reservoir contamination
Legionella risk factors
- cigarette smoking
- chronic lung disease
- older age
- biologic therapy
Legionella: clinical presentation
- Cough (blood-streaked sputum)
- GI symptoms (NVD)
- Rales and signs of consolidation
Legionella: CXR
patchy unilobar infiltrate that progresses to consolidation
-pleural effusion
Pontiac fever
mild form of legionella infection
- no respiratory
- self-limited
Legionella: diagnostic
- Sputum culture (if hospitalized)
2. Urinary antigen test* (still postiive after antibiotics unlike sputum)
Legionella: treatment
Azithromycin (or clarithromycin)
or
Fluroquinolone
x 10 -14 days! ***
Botulism: cause
Clostridium botulinum
gram-positive +
Botulism: pathophys
-blocks release of acetylcholine (esp. in excitatory synapses)
What should infants avoid eating?
honey (haven’t developed gut immunity to botulism)
Botulism: clinical presentation
- Bilateral cranial neuropathies
- DESCENDING WEAKNESS***
- blurred vision, diplopia, nystagmus, ptosis, dysphagia, dysarthria
- Urinary retention and constipation
EMG: compare and contrast MG and botulism
Botulism: wave amplitude increases the more it is stimulated
MG: wave amplitude decreases the more it is stimulated
Botulism: who do you call
- Health Department
2. CDC
Botulism: treatment
Equine serum heptavalent botulism antitoxin (within 24 hours)
Diphtheria: cause
Corynebacterium diphtheriae
gram positive bacillus
Diphtheria: clinical presentation
- Can happen anywhere in the URT
- Pharyngeal - gray membrane covering tonsils and pharynx ****
Name the 2 scary complications of Diphtheria
- Myocarditis (arrhythmias, heart block, heart failure)
2. Neuropathy (diplopia, slurred speech, dysphagia)
What are the non specific lab findings of diphtheria
- Elevated WBC
2. Proteinuria
Diphtheria: treatment
AIRWAY MANAGEMENT!
- Diphtheria equine antitoxin
- Penicillin (or erythromycin) x 14 days
What precautions need to be taken with Diphtheria
Respiratory droplet isolation until 3 negative oropharyngeal cultures
Tetanus: cause
Clostridium tetani
- Found in soil
- rod-shaped bacterium (transforms after inoculation)
Tetanus: patho
retrograde axonal transport within motor neuron
-blocks neurotransmission of inhibitory neurons
Tetanus: clinical presentation
Generalized (MC and severe of the 4 clinical patterns!)
- Trismus (lock jaw)**
- increased muscle tone
- painful spasms
- widespread autonomic instability (ex. labile HTN, fever)
Tetanus: treatment
- Metronidazole
- Tetanus immune globulin (neutralize toxins)
(also, benzos)
Tetanus prevention/post puncture wound
Immunization!
If puncture wound….
give vaccine + immune globulin if never boosted or >5 years since last booster
Lyme disease: etiology
Borrelia burgdorferi
- mc tick-borne illness
- white footed mouse and deer
- Ixodes scapularis (deer tick)***
- Spring and summer
How long do deer ticks need to feed to transmit lyme?
24 -36 hours
What is the name of the rash associated with Lyme?
erythemia migrans
Lyme early clinical manifestations
Early disseminated:
- Cardiac (ex. arrhythmias)
- Neurological (ex. aspetic meningitis, radiculopathy)
- Eyes (ex.conjunctivitis, keratitis)
Lyme late manifestions
- Musculoskeletal: arthritis esp in knee**
Lyme: diagnostic criteria
- Exposure to tick habitiat within 30 days of developing erythema migrans
What are the two important labs to help confirm Lyme disease
- ELISA antibody
- Western immunoblot assay
~elevated SED, LFTs
Lyme disease: Treatment
Doxycycline (10-14 days)
Lyme disease: pregnant lady (or kid <8 yrs)
Amoxicillin!
Who gets prophylactic antibiotics?
- Tick attached for 36+ hours
- Treatment can be started within 72 hours or tick removal
- > 20% of the ticks in the area are infected
- No contraindications to treatment
Rocky mountain spotted fever: cause
-Rickettsia rickettsii
gram-negative (obligate intracellular bacterium)
-Tick borne
Rocky mountain spotted fever: clinical presentation
Rash (blanching macules that transition to petechiae)
- ankles and wrists, spread to trunk
- Seen on palms and soles
Rocky mountain spotted fever: diagnostics
- Normal WBC count with immature bands
- Thrombocytopenia (prolonged PTT/PT)
- Hyponatremia
- Elevated LFTs
Rocky mountain spotted fever: treatment
Doxycycline
Start within 5 days of symptoms!
Epstein Barr virus: virus type
herpes virus
- transmitted by intimate contact with saliva
- associated with B cell lymphomas, Hodgkin lymphoma, nasopharyngeal carcinoma, gastric tumors)
EBV: classic symptoms
- tonsillitis/pharyngitis
- cervical lymphadenopathy**
- fever
What happens if you treat EBV with ampicillin cause you thought it was strep throat?
morbilliform rash!!!
What is the key finding on CBC for EBV?
lymphocytosis (WBC 12-18,000)
What is the best way to diagnose EBV?
Heterophile antibody test (+ for 3 months after onset)
EBV: best marker of acute infection
IgM and IgG antibodies against viral capsid antigen (VCA)
EBV: best marker of latent virus (present for life)
Nuclear antigen
if you see this, not an acute infection
EBV: treatment
Corticosteroids
-Restrict from playing sports for 4 weeks!
Cytomegalovirus: most common presentation in healthy individual vs. HIV
Healthy: CMV mono (looks similar to EBV)
HIV/AIDS: retinitis
CMV: treatment
Antiviral (ex. ganciclovir, valganciclovir, foscarnet, cidofovir)
Toxoplasmosis: etiology
Toxoplasma gondii (intracellular protozoan)
Toxoplasmosis: transmission
definitive host = cat
- contaminated food, water, meat from infected animal
- vertical transmission**
Toxoplasmosis: clinical presentation
- Bilateral symmetrical nontender cervical or occiptal adenopathy
- Chorioretinitis (visual loss or floaters)**
“headlights in the fog”
What is the scarriest thing to be concerned for if your immunocompromised patient get toxoplasmosis?
encephalitis with multiple necrotizing brain lesions!
Toxoplasmosis: diagnosis
ELISA
Toxoplasmosis: prophylaxis
TMP-SMX
treatment: pyrimethamine + sulfadiazine x 2-4 wks
Cryptococcosis: etiology
Cryptococcus neoformans
-encapsulated budding yeast found in soil, dried pigeon dung**
inhaled**
Cryptococcus treatment
Amphotericin B x14 days
then
fluconazole x8 weeks
Where does varicellla zoster become latent?
sensory dorsal root ganglia
VZV rash
- MC thoracic or lumbar dermatomes
- Opthalmic branch of trigeminal is SERIOUS!!!
- rash preceded by acute neuritis prodromal pain
VZV: treatment
- Antiviral therapy**
- start within 72 hours - Analgesia (NSAIDs or Opioids)
What is the name for herpes zoster oticus?
Ramsay Hunt Syndrome
Who gets the VZV vaccine?
60+ recommended
-Shingrix** (recombinant zoster vaccine)
