Infectious disease Flashcards
Which live attenuated viral vaccines are there?
- MMR vaccine (Measles, mumps, rubella)
- Varicella Zoster vaccine
- Polio vaccine (oral)
- Yellow fever vaccine
Which live attenuated bacterial vaccines are there?
- BCG vaccine
2. Tularemia vaccine (not safe or in use yet)
Which inactivated viral vaccines are there?
- Hepatitis B vaccine
- Influenza vaccine
- Polio vaccine (subcutaneous)
- Rabies vaccine
Which inactivated bacterial vaccines are there?
- DTP vaccine (Diphtheria, tetanus, pertussis)
- Anthrax vaccine
- H. influenza vaccine
- N. meningitidis vaccine
What neurological disorder can measles cause after several years of latency?
Subacute sclerosing panencephalitis
What oral rash is often seen in a patient with measles?
Koplik spots. They are seen 2-3 days before the rash appears.
Where does the measles rash usually first appear?
Rash first appears in the head area and then descends.
Characteristic symptom of mumps?
Enlargement of parotid salivary glands (unilateral in 25% of cases)
Can mumps lead to meningitis?
Yes. Before the vaccine was introduced it was the most common cause of viral meningitis.
For what patients is rubella dangerous?
Pregnant patients as it can cause congenital rubella sydrome or miscarriage
In what cases should immunisation (vaccination) be postponed?
If patient is suffering from acute febrile illness, especially respiratory
(Exception is made if there is a suspicion of rabies)
Are vaccines that contain egg contraindicated to persons allergic to egg?
No. Only if it causes a severe allergic reaction.
What patients should not receive live attenuated vaccines?
- Patients on steroid treatment
- Pregnant patients
- Immunocompromised patients (children with HIV should be vaccinated though)
What does the disease progression of HIV look like?
- HIV transmission
- Primary HIV infections
- Clinical latent period with or without persistent generalized lymphadenopathy
- Early symptomatic HIV infection
- AIDS (=CD4 count below 200)
- Advanced HIV infection (CD4 count below 50)
What does the primary HIV infection look like?
Mimics mononuleosis symptoms and occurs withing the first two to four weeks after someone is infected (but can take longer)
- Fever
- Lymphadenopathy
- Pharyngitis
How do you diagnose HIV?
ELISA and Western blott after that to confirm the diagnosis. After that, you can start testing the CD4 count and the viral load.
What is the normal CD4 cell count?
1000 cells/ul of blood
What AIDS defining illnesses are there?
- Candidiasis in the esophagus, bronchi, trachea
- Cryptococcosis (extrapulmonary)
- CMV infection of any other organ than liver, spleen or lymph nodes. (CD4 <50 if disseminated)
- Kaposi sarcoma (More common at CD4 <200, but can occur at any CD4 level)
- Lymphoma (especially non-hodgkin) (CD4 200-500)
- Mycobacterium avium complex (CD4 <50)
- Pneumocystis jirovecii (CD4 <200)
- Toxoplasmosis
- Tuberculosis (CD4 200-500 for pulmonary, <200 for miliary, but can occur at any CD4 level)
- Cervical cancer
- Recurrent pneumonia
- Sepsis due to non-typhoid salmonella
What complications of HIV can occur at any CD4 counts?
- Lymphoma
- Tuberculosis
- Kaposi sarcoma
- Herpes zoster
What is the most common AIDS-defining illness?
Pneumocystis jirovecii pneumonia
What is the treatment for Pneumocystis jirovecii pneumonia?
TMP-SMX. The treatment is the same as the prophylaxis.
What are the signs and symptoms of Pneumocystis jirovecii pneumonia?
Non-productive cough, dyspnea, normal sounds on auscultation
Interstitial infiltrates with ground glass appearance on X-ray
What are the most common causes for neurological complaint in AIDS?
- Toxoplasma gondii
- Primary lymphoma of the CNS
- Progressive multifocal leukoencephalopathy
What is the most common cerebral cerebral mass in AIDS patients?
CNS toxoplasmosis
What are the signs and symptoms of toxoplasmosis?
Headache, confusion, fever, lethargy, seizures, coma
What is progressive multifocal leukoencephalopathy caused by?
JC virus
How is progressive multifocal leukoencephalopathy diagnosed?
By MRI as it is demyelinising and not a mass-lesion
What is the most common manifestation of a systemic fungal infection in HIV positive patients?
Cryptococcosis
What is characteristic for cryptococcal meningitis?
Very high ICP
What is the treatment for cryptococcal meningitis?
- Fluconazole
- Amphotericin B (2nd line)
What is the goal of antiretroviral therapy?
Achieving a viral load under 50
What are the different classes of drugs in management of HIV?
- Entry inhibitors
- Nucleoside/nucleotide reverse transcriptase inhibitors (NRTI)
- Non-nucleoside reverse transcriptase inhibitors (NNRTI)
- Integrase inhibitors
- Protease inhibitors
Entry inhibitors
Interfere with binding, fusion and entry of HIV to the host cell by blocking one of several targets e.g. the CCR5 receptor.
Nucleoside/nucleotide reverse transcriptase inhibitors (NRTI)
Nucleoside/nucleotide analogues that inhibit reverse transcriptase
Side effect:
- Lipoatrophy (not as much of a problem w/ newer drugs)
- Mitochondrial toxicity (can lead to lactic acidosis!)
Non-nucleoside reverse transcriptase inhibitors (NNRTI)
Non-competitive inhibitors of reverse transcriptase
Integrase inhibitors
Inhibit the viral enzyme integrase, which is responsible for integration of viral DNA into the DNA of the infected cell.
Protease inhibitors
Block the viral protease enzyme necessary to produce mature virions.
Side effect:
- Metabolic alterations (increased visceral fat being the most common)
What classes of drugs does the most common HIV therapy consist of?
2 NRTIs + integrase inhibitor
When should antiretroviral therapy be initiated?
As soon as possible
Cerebrospinal fluid in normal lumbar puncture
- Clear fluid
- Opening pressure 10-20 cm H2O
- WBC 0-5 cells/microliter
- Glucose >60% of serum glucose
- Protein 15-45 mg/dl
Cerebrospinal fluid in bacterial meningitis
- Clear, cloudy or purulent fluid
- > 25 cm H2O opening pressure (=elevated)
- WBC >1000 cells/microliter (doesn’t have to be this high though)
- Glucose <40% of serum glucose
- Protein >50 mg/dl
Numbers that are “normal” do not rule out bacterial meningitis
Cerebrospinal fluid in viral meningitis
- Clear fluid
- Normal or elevated opening pressure
- WBC 10-1000 cells (lymphocytes)
- Glucose is normal, but can be low in HSV infection
- Protein is normal or a little elevated
Cerebrospinal fluid in tuberculosis meningitis
- Clear or opague (yellow-ish) fluid (due to high fibrinogen level)
- Elevated opening pressure
- 50-500 WBCs (lymphocytes)
- Glucose is lower than viral meningitis but higher than bacterial
- Protein is elevated. Not as much as in bacterial meningitis, but higher than viral.
- LOW CHLORINE!
Cerebrospinal fluid in fungal meningitis
- Clear or cloudy
- Elevated opening pressure
- WBC 10-500 cells
- Low glucose
- Elevated protein
What is the common cause of viral encephalitis?
Herpetic encephalitis (HSV-1)
When is lumbar puncture contraindicated?
- If patients displays signs of increased intracranial pressure
- Low platelet level
- Skin infection near the site of lumbar puncture
- Acute spinal cord trauma
- Severe scoliosis
What are the most common causes of aseptic meningitis?
- Arboviruses
- Enteroviruses
- Poliovirus
- Coxsackie virus
- Echovirus
- HSV-2
Signs and symptoms of aseptic meningitis
- Fever (usually low-grade in the initial stage and higher temperature at the onset of neurological signs)
- Headache (almost always present, often reported as severe)
- Nausea and vomiting
- Signs of meningeal irritation (positive Brudzinski or Kernig sign)
- Altered mental status
- Muscle ache
The absence of meningeal signs does not rule out meningitis
Signs and symptoms of encephalitis
- Alterations of consciousness
- Focal neurological signs
- Seizures
- Headache
- Fever
Common causes of encephalitis
- HSV-1
2. Arboviruses (TBE virus, yellow fever virus, dengue virus, japanese encephalitis virus, west nile virus)
What is the best diagnostic test in HSV encephalitis and what is the treatment?
MRI as you might see changes in the frontal and temporal lobe.
IV acyclovir is the treatment. Foscarnet in case of resistance.
Signs and symptoms of flavivirus encephalitis (e.g. west nile virus, japanese encephalitis)
- Parkinsonian movement disorder (masklike facies, tremors, cogwheel rigidity etc.)
- Upper motor neuron involvement (flaccid paralysis that resembles polio)
- Seizures (more common among children)
What empiric drug therapy is given if you suspect meningitis?
Steroids (dexamethasone) + antibiotics (3rd generation cephalosporine + ampicillin or meropenem as the only antibiotic) + acyclovir (if there is the slightest suspicion of HSV being the causative agent)
Steroids are given either before or with the antibiotics, not after.
These are the Swedish guidelines. In our exam, they probably want Vancomycin to be added to the therapy as well.
Signs and symptoms of bacterial meningitis
- Fever
- Chills
- Headache
- Signs of meningeal irritation
- Vomiting
- Confusion
- Petechiae (present in 50% of patients w/ meningococcal meningitis)
How do you diagnose bacterial meningitis?
Lumbar puncture is the only way to get a definitive diagnosis. CT is only done to exclude ICP or another lesion.
When should the dexamethasone therapy in case of meningitis be discontinued?
If it is not caused by S. pneumonia, it should be discontinued.
Signs and symptoms of tuberculosis meningitis
- Usually subacute or chronic presentation
- Persistent fever and increasing headache over a pariod of weeks or months
- Decreased chlorine in CSF examination
- Cranial nerve palsies
What are the common causes of bacterial meningitis?
- Pneumococci
- Meningococci
- Haemophilus influenzae
- Listeria monocytogenes
- Beta-hemolytic streptococci
- Mycobacterium tuberculosis
Who should be contacted if a patient has a spinal and/or brain abscess?
Neurosurgeon
What is a brain abscess?
Focal intracerebral infection that begins as a localized area of cerebritis and develops into a collection of pus surrounded by a well-vascularized capsule
Develops step by step Early cerebritis (Day 1-3) > Late cerebritis (Day 4-9) > Early encapsulated stage (Day 9-14) > Late encapsulated stage (Day >14)
Early cerebritis
- Patient usually doesn’t contact a doctor by this point
- Focal area of inflammation
- Can suddenly develop seizures or septic emboli
Late cerebritis
- Usually complains about headache that doesn’t respond to painkillers
- MRI can be used for diagnosis
- Expansion of cerebritis
Early capsulate stage
- Establishment of a ring-enhancing lesion
Where do brain abscesses most commonly originate from?
- Sinus infection
- Middle ear infection
- Tooth infection
Signs and symptoms of brain abscesses
A lot of abscesses are in the “silent” part of the brain and the signs and symptoms can be quite non-specific
- Headache (65%)
- Vomiting (52%)
- Fever (50%)
- Lethargy (45%)
- Seizures (33%) - sudden onset
- Papilledema (55%)
- Focal deficits (40%)
- Nuchal rigidity (18%)
How are brain abscesses treated?
Either with antibiotics or surgically. Antibiotic treatment usually lasts quite a long time.
<2 cm, antibiotics (surgery rarely required)
2-4 cm, variable
>4 cm, surgical drainage
3rd generation cephalosporin + metronidazole (empirical treatment)
Steroids are not given!
What is the best way to diagnose spinal abscesses?
MRI
Lumbar puncture is STRONGLY contraindicated!
What are the most common sources of infection for spinal abscesses?
- No source identified (30%)
- IV drug abusers (26%)
- Skin and soft tissue infection (22%)
- Spinal surgery (12%)
- Bone or joint infection (7%)
Bacteria usually access the epidural space by contiguous spread or hematogenous dissemination
Signs and symptoms of spinal abscesses
- Back pain and tenderness (the most common symptom)
- Fever
- Neurologic deficits
This is the classic triad, but only 8% of patients experience all of these symptoms
What is the most common localization of a spinal abscess?
Thoracic (44%)
Lumbosacral (35%)
Cervical (21%) < Most dangerous localization
What families of ticks can transmit pathogens to humans?
- Ixodidae (hard ticks)
- Argaside (soft ticks)
What bacteria is Lyme disease caused by?
The spirochete Borrelia burgdorferi
What are the three clinical stages or Lyme disease?
- Early localized
- Early disseminated
- Chronic disseminated
What is the clinical manifestation of early localized Lyme disease?
Erythema migrans
- 3 days - 1 month incubation time
- Macule or papule at the site of the bite which extends centrifugally and increasing to several dozen cm in diameter within 2 weeks
- Should atleast be 5 cm in diameter
- Occurs in 60-80% of cases
- Treat at once, no need for Ig test
How long time does it take for antibodies to appear in Lyme disease?
Several weeks (slides say 4-6, but can appear within 2-3)
What ocular manifestations can Lyme disease present with?
Uncommon, but:
Early -> Conjunctivitis, periorbital edema
Late -> Optic neuritis
What is the clinical manifestation of early disseminated Lyme disease?
Lymphocytoma
- Solitary, deep red, slightly tender nodule
- Appears at the site of the tick bite or remote from it (often earlobe in children and nipple in adults)
Atrioventricular block
- May progress to asystole
Cranial neuropathies
- Especially facial nerve palsy
What is the clinical manifestation of late disseminated Lyme disease?
Acrodermatitis chronica atrophicans
- More common in Europe
Joint involvement
- Usually the large joints
How is Lyme disease diagnosed?
Serology: ELISA + western blotting confirmation
What is the treatment for Lyme disease?
Doxycycline
How does Tularemia typically present and how is it transmitted?
Transmitted by
- Mosquito
- Tick bite
- Deer flies
- Direct contact with infected animal
- Contaminated water or meat
Ulceroglandular
- Tender lymphadenopathy
- Skin lesion appears either before, simultaneously or after the lymphadenopathy and starts as a red painful papule in the region draining into the involved lymph nodes
- The papule then undergoes necrosis, leaving a tender ulcer with a raised border
Glandular
- Enlargement of the lymph nodes, but without evident cutaneous lesions
- Fever
- Chills
- Headache
- Malaise
- Anorexia
- Fatigue
What is the 1st line drug when treating Tularemia?
Streptomycin
Ciprofloxacin in Sweden
What is tick paralysis?
Prolonged attachment of tick that causes paralysis. It beings in the lower extremities and ascends symmetrically. Rapid resolution of symptoms when tick is removed
What bacteria causes Rocky mountain spotted fever?
Rickettsia Ricketsii
What are the risk factors for Rocky mountain spotted fever?
- Male sex
- Exposure to dogs
- Residence in a grassy or wooden area
(Patient is usually a 5-9 year old child)
How does Rocky mountain spotted fever manifest clinically?
It usually begins with fever, headache and myalgia. After 3-5 days the patient develops a pathognomic rash. The rash is usually on the palms and soles.
How is Rocky mountain spotted fever treated?
Doxycycline
How does Babesiosis usually present clinically?
It is quite similar in presentation to malaria
- Malaise
- Fever
- Headache
- Hemolytic anemia
- Anorexia
- Drenching sweat
- Kidney failure
How is Babesiosis diagnosed?
Blood smear