General ID Flashcards

1
Q

MRSA Risk Factors

A

HA: recent abx, hospitalization, indwelling catheter, LTC pt

CA: day care, athletes, living in close quarters, IVDU, MSM

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2
Q

Tx options for MRSA

A

IV: vanco, linezolid, daptomycin
Oral: septra, doxy, clinda

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3
Q

When an MRSA+ abscess needs abx

A
>5cm 
Multiple lesions
Surrounding cellulitis
Systemic symptoms 
Poor response to initial I&D
Sig comorbidities (DM, transplant, immunosup)
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4
Q

How to eradicate MRSA colonization

A

Consider if recurrent MRSA infections or recurrent close contact transmission despite appropriate hygiene.

Mupirocin 2% ointment 0.5g nostrils BID x5d + skin cleansing antiseptic.

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5
Q

Pathogen that causes botulism

A

Clostridium botulinum.

Gram+ anaerobe, spore forming

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6
Q

MOA of botulism

A

Inhibits release of acetylcholine as NMJ resulting in neuromuscular blockade/flaccid descending paralysis

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7
Q

Typical bolutism presentation

A

Descending flaccid paralysis, mydriasis (dilated), ptosis, eventual respiratory paralysis (main cause of death)

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8
Q

Why don’t adults get botulism from eating honey?

A

Adult intestinal flora prevents colonization of the GI tract

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9
Q

Presentation of infant botulism (72% of cases)

A

Age <1 yr.
Typically from ingestion of honey or corn syrup.

Present w/ constipation, poor feeding, weak cry.
Decreased muscle tone, loss of head control.
Depressed DTRs.
50% present with respiratory failure.
No fever.

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10
Q

Presentation of foodborne botulism (25%)

A

Direct toxin ingestion, classically from home canned foods.
Incubation: 1 day (range 6hrs-10d).
Cranial nerve palsies (diplopia, dysphagia, dysarthria).
Descending paralysis and respiratory failure

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11
Q

Presentation of wound botulism (rare)

A

Classically from open wounds and injection drug use with ‘black tar’ heroin.

Incubation = 1 wk.
Similar presentation as foodborne but less severe/lower mortality

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12
Q

Diagnosis of botulism

A

Presumptive based on clinical picture, confirm with presence of toxin in blood/stool/food or growth of bacteria from wound.

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13
Q

What must be considered before giving antibiotics for wound botulism?

A

Infiltrate with Ig first to limit worsening of symptoms from cell lysis caused by antibiotics

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14
Q

Treatment of botulism (infant, foodborne)

A

1) Supportive +/- early intubation
2) Adults: trivalent antibodies derived from horse serum (neutralizes circulating toxin)
3) Infants: don’t use horse serum formulation as poor efficacy and high risk of anaphylaxis. Use human derived Ig (BIG-IV)
4) Decontam: AC or WBI for foodborne or infant if early enough presentation.

Antibiotics are NOT RECOMMENDED

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15
Q

Tx of wound botulism

A

Irrigate wound, administer antitoxin (trivalent horse ab) THEN give antibiotics (pen G and flagyl)

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16
Q

Pathogen causing tetanus

A

clostridium tetani

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17
Q

4 clinical patterns of presentation caused by tetanus

A

1) Local
2) Generalized (most common)
3) Neonatal
4) Cephalic

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18
Q

RF tetanus

A

temperate climate, immunosupp, old, IVDU, puncture wounds or crushed/devitalized tissue, inadequate immunization

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19
Q

MOA tetanus

A

Spores block release of GABA and glycine (inhib NTs) at motor endplates of skeletal muscle, SC, brain, symp NS –> spastic paralysis and tetany

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20
Q

Incubation period tetanus

A

1d to 1 mo (shorter = worse)

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21
Q

Symptoms of local tetanus

A

Muscle spasms near site of injury that resolve spontaneously in weeks to months. May progress to generalized.

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22
Q

Symptoms of generalized tetanus (80% of cases)

A
Diffuse muscle rigidity, periodic spasms. 
Causes trismus (lockjaw), sardonic smile, opisthotonus, respiratory failure.
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23
Q

Presentation neonatal tetanus

A

Occurs in developing countries when non-sterile instruments used to cut umbilical cord and mom is not immunized (no passive Ig).

Irritability, poor feeding.

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24
Q

Cephalic tetanus presentation

A

Secondary facial trauma or after otitis media.
CN dysfunction, typically CN VII
15-30% mortality.

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25
DDx for tetanus
Strychnine poisoning (pesticides, adultered street drugs), waxing/waning intense muscle contracts. Tx with benzo.
26
What is the spatula test for tetanus
Pt with tetanus uncontrollably bites down on tongue depressor when you touch their posterior pharynx. sens/sp >90%
27
Tx of tetanus
1) Aggressive supportive 2) Tetanus Ig (neutralizes circulating tetanospasmin). 3K-5K units IM. 3) Tetanus immunization 4) Benzos for muscle relaxation 5) Consider magnesium, labetolol for symp hyperactivity 6) May require NM blockade with paralytic Avoid wound debridement until Ig given
28
Tetanus prophylaxis
Clean wound, give TdaP if: - >10 yrs since last tetanus - <3 doses (incomplete primary series) or hx not known Dirty wound (large, bite, saliva/dirt/feces, >6hrs old, puncture, crush): Give TdaP if: - >5 yrs since last dose, incomplete primary series or immunization history unknown Give tetanus Ig if hx unknown or incomplete primary series
29
2 syndromes caused by disseminated gonococcal infection:
1) Purulent (septic arthritis): typically knee, ankle or wrist. No skin lesions. 2) Tenosynovitis, dermatitis, polyarthralgia syndrome: tenosynovitis of distal extremities, vesiculopustular peripheral lesions, asymmetric polyarthralgia (may progress to septic arthritis)
30
Pathogen that causes syphilis
Treponema pallidum (GN spirochete)
31
Incubation period for syphilis
2-4 wks
32
Symptoms of primary syphilis
Chancre: Painless genital ulcer with indurated border that spontaneously heals over 2-6wks
33
Symptoms of secondary syphilis
Occurs 4-8 wks after healing chancre. - Maculopapular rash, non-pruritic, spreads from trunk to extremities (may involve palms, soles) - Condyloma lata (wart-like genital lesions) - Flu-like illness (sore throat, low grade fevers, malaise, generalized lymphadenopathy)
34
Typical duration of latent syphilis
3-4 yrs
35
Types of presentations seen in tertiary syphilis
- Tabes dorsalis (myelopathy involving dorsal columns of spinal cord) - Dementia - Gummatous lesions of mucous membranes - Thoracic aortic aneurysm
36
Typical presentation of neurosyphilis
Can occur at any stage of infection. Acute neurosyphilis may be asymptomatic but typically presents with meningitis or a CNS vasculitis (stroke, HA, etc). Chronic neurosyphilis may present with tertiary symptoms as above.
37
How to test for syphilis
Non-treponemal testing: Tests for non-treponemal antibodies, thus non-specific, may get false positives. - RPR (rapid plasma reagin) - VDRL - Become positive >2wks post primary chancre (4-6 wks after infection) Treponemal: confirmatory testing. Stays positive for life. - FTA-ABS (serum fluorescent treponemal antibody absorption test) Can do dark field microscopy from a chancre or oral/genital lesion. Can use CSF VDRL to diagnose neurosyphilis in patients with positive FTA-ABS
38
Things that cause RPR/VDRL false positive
HIV, malaria, pneumonia, lupus
39
Tx for primary or secondary syphilis
Benzathine PCN 2.4 mil U IM | alt = doxy x14d
40
Tx for latent/tertiary syphilis
benzathine PCN 2.4mil U IM q7d x3 | alt doxy x28d
41
Tx of neurosyphilis
Aqueous pen G 3-4mil U IV q4h x10-14d | alt = daily benzathine PCN 2.4mil U IM x10-14d with probenacid QID
42
Types of influenza virus
A: most virulent, associated with pandemics. Further classified into types based on surface proteins (e.g. H1N1) B: regional/widespread epidemics q2-3yrs. C: associated with sporadic infections.
43
Symptoms of influenza
``` Incubation: 1-4 days. Characterized by: - Sudden onset high fever (2-4d) - HA, myalgias, fatigue, malaise - Coryza, sore throat, nonproductive cough - GI symptoms (more common in kids) ```
44
Timeframe to start antivirals for flu
only efficacious if started within 48hrs of symptom onset
45
Antivirals for flu
Oseltamavir, Zanamivir
46
Indications for tamiflu
Symptoms <48 hrs Symptoms requiring admission High risk for complications (<2yrs, >65yrs, hospitalized, children with long term aspirin use, pregnant, immunosupp, LTC)
47
What is reye syndrome
Occurs in children who take aspirin that get influenza or chicken pox. Causes an encephalitis/cerebral edema, hepatitis
48
Incubation period for mono
1-2 months
49
Frequency of hepatosplenomegaly in mono
>50%
50
Lab findings with mono
Transaminitis (95%) Atypical lymphocytes in blood smear +Heterophile antibody test (e.g. monospot- viral capsid IgM)
51
Risk of false negatives with monospot
If test+ and pt symptomatic, diagnostic. False neg rate: - 1st wk: 25% - 2nd wk: 5-10% If high clinical suspicion and neg test, repeat in 1 week or do EBV Ab testing. Often monospot negative in young children, get serology if you suspect EBV (note that children rarely get 'mono').
52
How long is monospot positive
Generally up to 6 wks, may last positive up to 1 yr
53
Complications of EBV infection
1) Airway obstruction from tonsillar hypertrophy (tx w/ steroids) 2) Splenic rupture 3) Hemolytic anemia, thrombocytopenia (tx w/ steroids) 4) Guillan barre 5) Bilateral bell's 6) Implicated in Burkitt and Hodgkin lymphoma and nasopharyngeal carcinoma
54
How rabies is transmitted
Bite, SCRATCH or open skin contact with saliva/secretions from infected animal. Also possible from aersol transmission from caves filled with bats. Reservoirs in NA: raccoons, foxes, skunks, bats.
55
Rabies symptoms at inoculation site
Pain, paresthesias, itching at site of bite/scratch
56
symptoms of encephalitic form of rabies
Periodic episodes of hyperactivity, restlessness or agitation. Hypersalivation. Periodic spasms in response to stimuli including inspiratory (aerophobia) and pharyngeal (hydrophobia)
57
Describe paralytic form of rabies
Presents with GBS like symptoms including progressive paralysis with urinary incontinence.
58
How rabies is Dx'd
identification of virus from saliva (most common), punch biopsy of hair-bearing skin from nap of neck, serum, csf
59
Who does/doesnt get rabies prophylaxis: dog/cat/cat
If health/captured -> observe for 10d and only tx if symptoms develop. Escaped -> contact public health Sick -> start HRIG, vaccination
60
Who does/doesnt get rabies prophylaxis: skunks/raccoons/foxes/bats
Captured -> start HRIG, vaccination series then stop series if euthanized animal tests positive. Escaped -> HRIG and vaccination series
61
Rabies tx if bite from: squirrel, rat, mouse, rabbits
Consult public health but almost never requires treatment
62
How rabies prophylaxis is done
Clean wound. Give as much of the Ig as possible around the site, the rest IM. Administer rabies vaccine on days 0,3,7,14
63
How to do rabies prophylaxis if person is vaccinated
Clean wound. Rabies vaccine on days 0, 3. No Ig required.