Infectious Disease Flashcards
This deck covers Chapters 121-130 in Rosens, compromising all of infectious disease.
A 62 yo female had a tooth pulled 4 days ago. She now has severe neck pain with swelling. It feels woody on palpation.
Answer the following:
- Diagnosis
- Etiology
- Symptoms
- Treatment
Diagnosis
- Ludwig’s angina
Etiology
- Deep space infection
- Submental, submandibular, sublingual spaces
- Mixed flora (GAS, Bacteroides)
- Typically from intra-oral/intra-pharyngeal sources
Symptoms
- Swelling
- Fever
- Shortness of breath
- Impaired neck mobility
- Toxic appearing
Treatment
- Pip-Tazo + Vancomycin + Clindamycin
- ENT Consult in ED
- Awake fiberoptic intubation, if necessary
You diagnose a 14-year-old female with pertussis. She lives at home with her parents and a 6-month-old brother.
Outline the stages of Pertussis and your management
Stages
- Catarrhal (1-2 weeks) - infectious
- Paroxysmal phase (1-2 months)
- Convalescent phase
Management
- Booster vaccine
- Azithromycin (5 days)
- Notify public health
- Self-isolation for 3 weeks
- All close contacts receive booster vaccine and Azithro
- Household
- Daycare
- Child < 1-year-old
- 3rd-trimester pregnancy
A 35-year-old male presents with a wound. Explain your approach to tetanus prophylaxis
If wound clean and:
- Immunized <10 years ago = do nothing
- Immunized >10 years ago = Td vaccine
- Never immunized = Td vaccine
If wound dirty and:
- Immunized <5 years ago = do nothing
- Immunized >5 years ago = Td vaccine
- Never immunized = Td vaccine + HTIG
- HTIG dose = 250 U IM
Dirty Defined As:
- > 6 hours old
- > 1 cm deep
- Contaminated (dirt, feces, soil, saliva)
- Puncture
- Stellate
- Avulsions
- Denervated
- Ischemic
- Infected
- Missiles
- Crush
- Burns
- Frostbite
A kid comes in walking with a limp. Severe decreased ROM of the hip. He is febrile. You suspect a septic hip.
What criteria can be used to diagnose this?
Kocher Criteria
NEWF
- NWB on the affected side
- ESR > 40
- WBC > 12
- Fever (T >38.5)
Describe the signs and symptoms of Ebola. How long after a possible exposure should you be worried?
Ebola Virus
Transmission
- Human-to-Human
- Direct contact with blood + bodily fluids
Incubation Period
- Up to 3 weeks
Who to suspect it in
- Travel to an endemic country
- Contact with confirmed Ebola patient and symptomatic
Symptoms
- Sudden onset fever, malaise, myalgia, severe H/A
- Conjunctivitis, pharyngitis, N/V/D
- Hepatic + renal impairment
- Maculopapular or petechial rash
- Mucosal bleeding (50%)
- Multiorgan failure, shock, and death
Describe the epidemiology, pathophysiology, and clinical features of Staphylococcal Scalded Skin Syndrome (SSSS)
Epidemiology
- Children (6 months – 6 years)
- Mortality = 3%
- Adults
- Mortality = 50%
Pathophysiology
- Toxin-producing S. aureus
- Epidermolytic toxin A or B
- Acts on Desmoglein 1 protein (Dsg1)
- Results in the separation of the skin
Clinical Presentation
- Positive Nikolsky’s sign
- Erythema
- Blisters, bullae, and vesicles
List FIVE DDx for tetanus
- Strychnine Poisoning
- Dystonic Reaction
- Hypocalcemia
- Status Epilepticus
- Rabies
What is the most common cause of focal intracranial mass lesions in HIV infection?
Toxoplasmosis
- Parasitic disease
- Poorly cooked food w cysts or cat feces exposure
- ½ of people are infected by toxo but have no symptoms
Clinical
- Headache
- Fever
- Altered mental status
- Seizures, focal deficits
CT (with contrast) Features
- Ring enhancing lesions
- Multiple lesions
- Basal ganglia and corticomedullary area
Treatment
- Pyrimethamine 100-200mg PO then 50-100 mg/day
- Sulfadiazine 4-8 g/day PO
- Folinic acid 1 mg/day PO (prevents pancytopenia)
List FOUR clinical and FOUR lab findings that are criteria for severe malaria and poor prognosis
Clinical
- GCS <11
- Weakness
- Seizures (>2/day)
- Pulmonary edema (Hypoxia + RR >30)
- Bleeding
- Shock
Lab
- Hypoglycemia (<2.2 mmol/L)
- Acidosis (Base Deficit >8, Bicarb <15, Lactate >5)
- Anemia (HgB <70 adults, <50 children under 12, HCT <15%)
- Renal impairment (Cr >265, BUN >20)
- Bilirubin >50
- Parasite count >10% (for P. falciparum)
What is the causative agent in RMSF? How does it cause disease? What is the vector?
Rickettsia rickettsii
- Obligate intracellular bacteria
- Invades vascular endothelium causing vasculitis
Vector
- Rocky Mountain wood tick (Dermacentor andersoni)
- Dog tick (Dermacentor variabilis)
List the culprit organisms and treatment regimens for septic arthritis if the Gram’s stain shows:
- Gram + cocci
- Gram – cocci (sexually active patient)
- Gram – bacilli
- Gram + bacilli
Gram + cocci
- S. aureus
Gram – cocci (sexually active patient)
- N. gonorrhea
Gram – bacilli
- E. coli, P. aeuriginosa
Gram + bacilli
- P. acnes
List SIX rashes that can affect hands/soles of feet
- Secondary syphilis
- RMSF
- Coxsackie (HFM)
- Smallpox
- Kawasaki
- Meningococcemia
- Endocarditis
- DIC
What are the TWO pneumococcal vaccines available in Canada? When are they indicated?
PREVNAR-13
- Pneumococcal 13-valent conjugate vaccine
- Used to prevent IPD (invasive pneumococcal disease)
- Indications:
- All infants at 2 mo, 4 mo, 12 mo
PNEUMOVAX-23
- Pneumococcal 23-valent polysaccharide vaccine
- Indications
- All adults ≥ 65 years
- ‘Other’: homeless, alcoholic, smoker, drug user
- Immunocompetent adults + high risk for IPD
- Immunocompromised adults + high risk for IPD
List potential regimens for drug-resistant TB
Usually ‘RIPE’, replace I with a fluoroquinolone.
- Rifamipin
- Pyrazinamide
- Ethambutol
- Fluoroquinolone
List FOUR features of osteomyelitis on plain XR
- Involcrum (Periosteal reaction)
- Lucent areas
- Lytic lesions surrounded by dense sclerotic bone
- Sequestra
- Deep soft tissue swelling & fascial plane separation
- Altered fat interfaces
Provide a differential diagnosis for respiratory infections in HIV+ patients based on CD4 count
CD4 >200
- Regular pneumonia
CD4 <200
- PCP, Histo, Cryptococcus, TB
CD4 <50
- PCP, MAC, CMV, and everything above
What is the typical presentation of septic arthritis (clinical or lab)?
Symptoms
- Fever
- Joint pain
- Malaise
Lab Tests (C’s)
- Cell count (WBC >50 cutoff)
- Crystals
- Chemistry (Lactate, glucose, protein)
- Culture
- Gram stain
What are 5 complications of pertussis? How is it diagnosed?
Diagnosis
- NP swab + PCR (3-7 days for results)
Complications
- Respiratory failure
- Hernias
- Hemoptysis
- Pneumothorax
- Subcutaneous emphysema
Your patient has a parasitemia of 15% and it’s falciparum. Outline your management.
Severe Malaria Treatment (AM QD)
- Option A (‘AM’): Artesunate + Malarone IV
- Preferred
- Option B (‘QD’): Quinidine + Doxycycline IV
- Admit to ICU
How would you treat meningococcemia? Are steroids indicated for bacterial meningitis?
Treatment
- Ceftriaxone 2g IV q12h
- Vancomycin 15 mg/kg q12h
- Dexamethasone 8 mg IV
* Decreased mortality in S. pneumoniae
* Decreased hearing loss in H. influenzae
Outline your management of a patient with tetanus
Supportive Care
- Muscle spasms
- Benzodiazepines (*diazepam is the best-studied)
- Dantrolene (adjunct)
- MgSO4 (improved spasm control)
- Airway Protection (if above fails)
- Avoid sux
- Autonomic instability
- Labetalol or propranolol
Elimination of Tetanospasmin (TS) & Active Immunization
- HTIG 250 IU IM
- Neutralizes any circulating toxin
- Neutralizes toxin at the site of production
- Reduces mortality
- Td 0.5 mL IM
- Give at a separate site
Prevention of further toxin production
- Wound debridement
- Metronidazole 500 mg IV/PO Q6H (drug of choice)
- Avoid PCN which inhibits GABA and synergizes with TS
Discuss Rabies post-exposure prophylaxis
Wound Care
- Scrub with soap/water
Tetanus prophylaxis
- Td 0.5 mL IM (if not vaccinated)
Human Rabies IG (HRIG)
- HRIG 20 IU/kg
- Infiltrate full dose into and around the wound
- Remainder is given IM
Human Diploid Cell Vaccine (HDCV)
- If never vaccinated:
- Days 0, 3, 7, 14, 28 (5 doses)
- If previously vaccinated:
- Days 0 and 3 (2 doses)
Chikungunya. Describe its vector, duration of illness, and complications.
Vector
- Aedes mosquitoes
Symptoms
- Fever - usually ends abruptly after 2 days
- Arthralgia/Arthritis - significant
- Headache
- Insomnia
- Rash
Diagnosis
- Serology, RT-PCR
Treatment
- NSAIDs
Complications
- Myocarditis
- Hepatitis
- Nephritis
- Meningitis
- Guillain-Barré syndrome
- Cranial nerve palsies
What is the causative agent in Diphtheria? Explain the pathophysiology, types of disease, and management.
Etiology
- Corynebacterium Diptherae
Types
- Respiratory Diphtheria
- Greatest toxicity
- Pharyngeal, Nasal, Laryngeal
- Cutaneous Diphtheria
- Least toxic
Pathophysiology
- Produces exotoxin that inhibits cellular protein synthesis
- Affects: Nervous System + Heart + Kidneys
Treatment
- Erythromycin 50 mg/kg/day
- Diphtheria antitoxin
- Vaccinate
- Self-isolation
- Notify Public Health
- Vaccinate close contacts
Which ONE parasite is well known to cause cardiomyopathy?
Chagas Disease
Parasite
- Trypanosoma cruzi
Symptoms
- Acute (1 – 2 months)
- Fever
- Facial and dependent extremity edema
- HSM, LAD
- Peripheral smear: lymphocytosis
- Elevated LFTs
- Chronic (25% of patients)
- Cardiac
* Invasion of muscle + fibrosis/inflammation
* Bradycardia, BBBs, Heart blocks, VT/VF - GI symptoms
Treatment
- Nifurtimox 2 mg/kg PO QID x4 months
- Alternative: Benznidazole
Describe the clinical presentation and treatment of cryptococcal infection in HIV infected patients.
Clinical Presentation
- Fever
- Headache
- Visual disturbance
- Seizures
- Usually CD4 < 100
- Causes focal or diffuse meningoencephalitis
Treatment
- 3 phases: induction, consolidation, maintenance
- If abnormal mental status
- Amphotericin B 0.7 mg/kg/day IV
- +/- 5-Flucytosine
- If normal mental status
- Fluconazole 400 mg/day PO
List guidelines for the management after accidental exposure to TB at work? What FOUR populations get PEP?
If exposed at work
- Get a TB skin test early for baseline
- Re-test in 3 months to see if there is the conversion
PEP INH
- Significant exposure in PPD Negative person
- PPD Negative who converts after exposure
- PPD Positive and no pre-exposure PPD available
- Immunocompromised <35 yo
Outline the WHO pandemic phases
Phase 1
- Infection in animals only
Phase 2
- Isolated animal-to-human transmission
Phase 3
- Sporadic human-to-human transmission
- Not enough for community outbreak
Phase 4
- Human-to-human transmission
- Able to sustain community-level outbreaks
Phase 5
- Human-to-human transmission
- Spread to 2+ countries in one WHO region
Phase 6
- Human-to-human transmission
- Spread to at least two WHO regions
Outline the stages of HIV infection as per the CDC surveillance case definitions
Stage 1
- CD4 >500
- No AIDS-defining illness
Stage 2
- CD4 200-499
- No AIDS-defining illness
Stage 3
- CD4 <200
- Any AIDS-defining illness present
List SIX complications of severe P. falciparum malaria
- Cerebral malaria
* Cerebral edema + encephalopathy - Metabolic acidosis
- Severe anemia
- Pulmonary edema
- Hypoglycemia
- AKI
- DIC
- Death
Name 4 complications of measles.
- Sub-acute sclerosing panencephalitis (SSPE)
- Laryngitis
- Tracheobronchitis
- Pneumonitis
- Secondary bacterial pneumonia
- Encephalomyelitis
- Vitamin A deficiency & blindness
List signs & symptoms of RMSF
Constitutional
- Fever, malaise
Neurologic
- H/A, meningismus, cerebral vasculitis
- Ataxia
Cardiac
- LV dysfunction
- Arrhythmias (1st deg AVB, A fib)
- Cardiac enlargement on CXR
- ECG: nonspecific ST-T changes
Pulmonary
- Interstitial pneumonitis
MSK
- Severe myalgias
Hematologic
- DIC (fulminant cases)
Dermatologic
- Rash
- Initially:
* 1 – 5 mm pink to red macules
* Blanches
* Begins on ankles & wrists
* Palms + Soles (50%)
* Spreads centripetally to forearms, legs, thigh, trunk +/- face
* Enhanced by warm compresses
* Not palpable - 2 – 3 days
* Becomes maculopapular
* Deepens in redness
* Palpable
* No longer blanches
Rumpel-Leede phenomenon
- Rash enhanced by tourniquet or BP cuff
- Distal shower of petechiae that occurs immediately after release of a tourniquet or BP cuff
List 10 conditions that require droplet precaution
- Adenovirus, respiratory strains
- Bocavirus
- Coronavirus
- Diphtheria, pharyngeal
- H. influenzae, in children
- Human metapneumovirus
- Influenza, seasonal, avian
- Meningococcus
- Monkeypox
- Mumps
- Mycoplasma pneumoniae
- Parainfluenza virus
- Parvovirus B-19
- Pertussis
- Plague, pneumonic
- RSV
- Rhinovirus
- Rubella
- SARS
- Smallpox
- Streptococcus, Group A
- Scarlet fever
- Viral hemorrhagic fevers
List EIGHT DDx for botulism
- GBS
- Tick paralysis
- Myasthenia gravis
- Lambert-Eaton syndrome
- Diphtheria
- Brainstem CVA
- Anticholinergics
- Organophosphates
- Dystonic reactions
- Heavy-metal poisoning
- Mg toxicity
- Paralytic shellfish poisoning
List 8 risk factors for necrotizing fasciitis (NF)
- DM
- Vascular insufficiency
- Immunosuppression
- Penetrating trauma
- Post-surgical
- Varicella infection (+NSAIDs!!)
- IVDU
- Burns
- Childbirth
Staphylococcal scalded skin syndrome vs. TEN
Staph Scalded Skin Syndrome
- Nikolski
- Oral mucosal sparing
- Unwell, but not shocky
- No history of drug exposure
- Responds to antibiotics
Toxic Epidermal Necrolysis
- Nikolski at the lesion
- Full-thickness of skin
- Oral mucosal regions involved
- Very unwell
- Drug exposure
List 5 host and 5 environmental risk factors for tuberculosis
Environmental Factors
- Close contacts
- Health care workers
- Birth in TB endemic area
- Overcrowding/poor ventilation
- Low SES
- Homeless
- Longterm care facilities
- Prisons
Host Factors
- HIV+
- Elderly
- IVDU
- Steroid use, immunosuppressive tx
- DM2
- Hematologic malignancy
- Malnourished
What are the characteristics of neonatal & infant bone infections? How does this differ compared to children aged 1 – 17 years & adults?
Neonates/Infants
- Spreads from metaphysis to the epiphysis
- Vessels cross growth plate
- No pressure-related necrosis
- Cortex allows the release of pressure
- Develop abscesses; Involucrum formation
Children Age 1 – 17 Years
- No spread to the epiphysis
- Epiphyseal plate = avascular
- No pressure-related necrosis
- Cortex still allows the release of pressure
- Subperiosteal abscess formation
Adults
- Spread from metaphysis to epiphysis again
- Due to anastomosis of vessels across the plate
- Pressure-related necrosis
- No abscess formation