Infectious Disease Flashcards
1
Q
Most commonly identified viruses
causing sporadic cases of acute encephalitis in immunocompetent adults
A
Herpesvirus, VZV, EBV
2
Q
CSF sample to be taken for encephalitis
A
20mL, 5-10mL frozen for study
3
Q
CSF profile of viral encephalitis
A
A. Lymphocytic pleocytosis,
*>5cells/mcL in immunocompetent indls
* Severely Immunocompromised: May fail to mount a CSF inflammatory response
* > 1000/mcL: Non-viral infection; arbovirus, mumps, LCMV
B. Mildly elevated protein conc
C. Normal gluc conc
- Atypical Lymphocytes: CMV, HSV, enteroviruses
- WNV encephalitis: Plasmacytoid or Mollaret-like large mononuclear cells
- Persistent CSF neutrophilia: Bacterial infection, leptospirosis, amebic infection, and noninfectious processes - acute hemorrhagic leukoencephalitis
4
Q
Primary diagnostic test for CNS infections caused by CMV, EBV, HHV-6, and enteroviruses
A
CSF PCR
- HSV CSF PCR (sensitivity 96%; specificity ~99%)
5
Q
CSF Ab testing of value to which patients
A
> 1 week in duration and CSF PCR negative for HSV
6
Q
Diagnostic of WNV encephaltiis
A
WNV IgM Ab
- IgM antibodies do not cross the blood-brain barrier, and their presence in CSF is therefore indicative of intrathecal synthesis.
- Increases 10% per day after illness onset 70-80% by end of first week
7
Q
Imaging findings of HSV encephalitis
A
Focal findings: consider HSV encephalitis
1. T2 weighted FLAIR or DW MRI: increased signal intensity in the frontotemporal, cingulate or insular regions of the brain
2. CT: focal areas of low absorption, mass effect, contrast enhancement
3. EEG: Periodic focal temporal lobe spikes on background of slow or low-amplitude (flattened act)
* periodic, stereotyped, sharp-and-slow complexes, one or both temporal lobes and repeating at regular intervals of 2-3 s
8
Q
Imaging findings of WNV encephalitis
A
FLAIR: deep brain- thalamus, basal ganglia, brainstem abnormalities
EEG: Generalized slowing, anteriorly prominent
9
Q
Imaging findings of VZV
A
- multifocal areas of hemorrhagic and ischemic infarction, reflecting the tendency of this virus to produce a CNS vasculopathy rather than a true encephalitis
10
Q
Imaging findings of CMV
A
Enlarged ventricles with areas of increased T2 on MRI- ventricles and subependymal enhancement on T1 weighted
11
Q
Indication of Brain Biopsy for encephalitis (4)
A
- CSF PCR studies fail to lead to a specific diagnosis
- Have focal abnormalities on MRI
- No serologic evidence of autoimmune disease
- Show progressive clinical deterioration despite treatment with acyclovir and supportive therapy
12
Q
Diagnosis of rabies virus antigen
A
Virus Ag in brain tissue or in neural innervation of hair follicles at the nape or neck
13
Q
Treatment of HSV, EVB, VZV encephalitis
A
Acyclovir 10mg/kg IV every 8h (max 30mg/kg/d) x 21 days - started empirically if suspecting viral encephalitis, especially focal features
14
Q
Treatment of HSV encephalitis
A
Ganciclovir
* Induction: 5mg/kg every 12h IV at constant rate over 1h (severe neurologic illness)
* Maintenance: 5mg/kg OD indefinitely
* Continued until: decline in CSF pleocytosis and reduced CSF CMV DNA copy number on quantitative PCR testing
Foscarnet
I: 60mg/kg every 8h constant infusion over 1h x 14-21 days
* Extend if failed to show a decline in CSF pleocytosis and reduction in CSF CMV DNA
M: 60-120mg/kg/d
Cidofovir: Nucleotide analogue for CMV retinitis
* 5mg/kg IV once weekly x 2 weeks then biweekly for 2 or more additional doses
* Prehydrated with normal saline 1L over 1-2h then probenecid
* Nephrotoxicity
15
Q
MRI findings of progressive multifocal leukoencephalopathy
A
- multifocal asymmetric, coalescing WM lesions located periventricularly in the centrum semiovale, in the parietal-occipital region and in cerebellum
- Increased signal on T2 and FLAIR images
- Decreased on T1-weighted images
- HIV-PML: Non-enhancing
- Immunomodulatory: Peripheral ring enhancement
16
Q
Management of progressive multifocal leukoencephalopathy
A
- 5HT2a receptor Mirtazapine: inhibit binding of JCV to its receptor on oligodendrocytes
- Interferon alpha
- Cytarabine: breakdown of BBB allows sufficient CSF penetration
- Severe CNS inflammatory syndrome (IRIS): clinical worsening, CSF pleocytosis, appearance of new enhancing MRI lesions
- Tx: IV glucocorticoids
- Natalizumab: STOPPED
- Tx: Plasma exchange or immunoadsorption
17
Q
Initial presentation of Subacute Sclerosing Panencephalitis
A
Poor school performance, mood and personality changes
18
Q
Most common organism for Community-acquired bacterial meningitis
A
Streptococcus pneumoniae (~50%)
Neisseria meningitidis (~25%)
Group B strep (~15%)
L. monocytogenes (~10%)
19
Q
Most important predisposing condition for s. pneumoniae meningitis
A
pneumococcal pneumonia
- RF: sinusitis or otitis media, alcoholism, DM, splenectomy, hypogammaglobulinemia, complement deficiency, head trauma with basilar skull fracture, CSF rhinorrhea
20
Q
Bacteria that complicates neurosurgical procedures and head trauma associated CSF rhinorrhea or otorrhea
A
Gram negative bacilli
21
Q
Bacteria following invasive neurosurgical procedures such as shunting, ommaya reservoirs
A
S. aureus and CONS
22
Q
Presentation of patient’s with raised ICP
A
- Deteriorating or reduced level of consciousness, papilledema, dilated poorly reactive pupils, 6th nerve palsies, decerebrate posturing, cushing reflex
- Cushing reflex: bradycardia, hypertension, irregular respirations
23
Q
Most disastrous complication of increased ICP
A
Cerebral herniation
24
Q
Indications to proceed with lumbar puncture without prior neuroimaging (4)
A
- Immunocompetent patient
- no known history of recent head trauma
- a normal level of consciousness
- no evidence of papilledema or focal neurologic deficits
25
CLASSIC CSF Abnormalities in BACTERIAL MENINGITIS
1. PMN leukocytosis (>100 cells/uL in 90%)
2. Decreased CSF Glucose
* <40 mg/dL
* CSF/serum glucose ratio of <0.4 in ~60%
3. Increase protein concentration (>45 mg/dL in 90%)
4. Increased opening pressure (>180 mmH2O in 90%)
* CSF Glucose concentrations <40mg/dl (Abnormal)
* CSF glucose concentration of zero= bacterial meningitis
* CSF/serum glucose <0.6 = CSF glucose con'c is LOW
* CSF/serum glucose <0.4 = HIGHLY suggestive of BAC MEN (may be seen in fungal, TB and carcinomatous meningitis)
26
Empirical therapy of Community-Acquired Suspected bacterial meningitis in children and adults
Dexamethasone + Third- or Fourth-Gen cephalosporins (Ceftriaxone/Cefotaxime/Cefepime) and Vancomycin plus (Acyclocivr or Doxycycline)
27
Treatment for susceptible S. pneumonia, group B strep, H. influenza and adequate coverage for N. meningitides
Ceftriaxone or Cefotaxime
28
When to add Ampicillin to empirical regimen in Bac Men?
For coverage of L. monocytogenes, <3 months of age, those > 55, those with imapired cell mediated immunity
* AMPICILLIN for at least 3 weeks
29
When to add Metronidazole to empirical regimen in Bac Men?
Gram-negative anaerobes in patients with otitis, sinusitis,
or mastoiditis
30
Empiric regimen for HA meningitis, particulalry during neurosurgical procedures
* Cover for Staph, gram neg including P. aeruginosa
* Vancomycin and Ceftazidime OR Meropenem
* MEROPENEM SHOULD NOT BE USED AS MONOTHERAPY!!!
31
Treatment of Meningococcal Meningitis?
* PENICILLIN G - antibiotic of choice for Penicillin-seinsitive
* CEFOTAXIME / CEFTRIAXONE - if with Penicillin resistance
* Uncomplicated: 7 day course
32
Meningococcal hemoprophylaxis for index case and close all contacts (3)
1. RIFAMPIN 600 mg every 12 h for 2 days in adults
2. Alternative: Azithromycin 500 mg x1 dose
3. Alternative: Ceftriaxone 250 mg IM x1dose
* Close contacts are defined as individuals who have had contact with oropharyngeal secretions, either through kissing or by sharing toys, beverages, or cigarettes.
33
When do you repeat LP in patients with S. pneumoniae meningitis?
Repeat LP performed 24-36H after initiation of antimicrobial therapy to document sterilization of CSF
Failure to sterilize the CSF after 24–36 h of antibiotic therapy should be considered presumptive evidence of antibiotic resistance.
Penicillin- and cephalosporin-resistant strains of S. pneumoniae who do not respond to intravenous vancomycin alone may benefit from the addition of intraventricular vancomycin.
34
Regimen to be added with Listeria Menigitides for critically ill patient
Gentamicin (2 mg/kg loading dose, then 7.5 mg/kg per day
given every 8 h and adjusted for serum levels and renal function).
35
Alternative for patients with L. monocytogenes menigitis with penicillin-allergy?
* COTRIMOXAZOLE - alternative in penicillin-allergic patients
* TMP 10-20mg/kg/day
* SMX 50-100mg/kg/d every 6 hours
36
Regimen for susceptible strains of S. aureus or CONS
NAFCILLIN
37
Drug of choice for MRSA and for patients allergic to penicillin
VANCOMYCIN
* If the CSF is not sterilized after 48 h of intravenous vancomycin therapy, then either intraventricular or intrathecal vancomycin, 20 mg once daily, can be added.
38
Regimen for gram negative bacilliary meningitis (susceptible and with P. aeruginosa), and recommended duration?
cefotaxime, ceftriaxone, and ceftazidime—are equally
efficacious for the treatment of gram-negative bacillary meningitis
If with P. aeroginosa: Ceftazidime or Meropenem
Recommended duration: 3 weeks
39
When to give adjuvant Dexamethasone in Meningitis?
* 20 mins BEFORE antibiotics, or not later than concurrent with the first dose of antibiotics - inhibits the production of TNF-alpha abs macrophages and micoglia only if it is administered before the cells are activated by endotoxin
40
Emergency treatment of increased ICP (3)
* Elevation of patient’s head to 30-45 degrees
* Intubation and hyperventilation (PaCO2 25-30mmHg)
* Mannitol
41
The risk of death from bacterial meningitis increases with (6)
1. Decreased level of sensorium on admission
2. Onset of seizures within 24H of admission
3. Signs of increased ICP
4. Infants and elderly >50
5. Presence of co-morbidities including SHOCK and/or need for MECH VENT
6. Delay initiation of treatment
42
CSF findings of viral meningitis
1. Pleocytosis (25–500/μL, can exceed 1,000/μL in some infections like LCMV or mumps).
* WNV: PMN pleocytosis in 45%, persist for week or longer before shifting to lymphocytic pleocyotosis
* CMV: PMN pleocytosis with low glucose
2. Normal or slightly elevated protein concentration: 0.2–0.8 g/L (20-80mg/dL)
* Normal glucose concentration
* May be low in 10–30% of cases (e.g., mumps, LCMV).
3. Normal or mildly elevated opening pressure: 100–350 mmH2O
43
Gold standard diagnostic procedure for viral meningitis
Polymerase Chain Reaction (PCR)
* Enterovirus, HSV, VZV, CMV, EBV, and HHV-6
* HSV DNA in recurrent episodes of aseptic meningitis, even with negative viral cultures.
44
Clues for Bacterial Meningitis vs. Aseptic Meningitis
* CSF protein >0.5 g/L: Sensitivity 89%, specificity 78%.
* Serum procalcitonin >0.5 ng/mL: Sensitivity 89%, specificity 89%.
* Bacterial meningitis score (negative predictive value 99.7%):
* Negative CSF Gram’s stain.
* CSF neutrophil count <1000 cells/μL.
* CSF protein <80 mg/dL.
* Peripheral ANC <10,000 cells/μL.
* No prior history/current presence of seizures.
45
When to hospitalize patients with viral meningitis?
1. immunocompromised patients
2. altered consciousness, seizures
3. Atypical CSF profiles
4. focal neurological signs and symptoms suggesting possibility of encephalitis or parenchymal brain involvement
46
Management of HSV-1, HSV-2, EBV, VZV meningitis
IV acyclovir (15–30 mg/kg/day in 3 doses) followed by oral drugs (acyclovir, famciclovir, valacyclovir)
Total course: 7–14 days.
47
Lab findings of tuberculous meningitis?
CSF Findings:
1. Elevated opening pressure
2. ymphocytic pleocytosis (10-500
3. elevated protein 1-5g/L
4. decreased glucose 20-40mg/dL.
Smear: AFB in the CSF (often 10–40% positive).
Culture: Takes 4-8 weeks; Positive in ~50% of cases, gold standard.
PCR: For M. tuberculosis DNA.
48
S/Sx, lab findings highly suggestive of tuberculous meningitis
Unrelenting headache, Stiff neck, fatigue, night sweats, and fever with a CSF lymphocytic pleocytosis
and a mildly decreased glucose concentration
49
Management of tuberculous meningitis
* Empirical therapy: Start with isoniazid (300 mg/d), rifampin (10 mg/kg/d), pyrazinamide (30 mg/kg/d), ethambutol (15–25 mg/kg/d), and pyridoxine (50 mg/d).
* Adjustments: Discontinue ethambutol if M. tuberculosis is sensitive; stop pyrazinamide after 8 weeks if responsive.
* Duration: Isoniazid and rifampin for 6–12 months, extended to 9–12 months for slow resolution or with positive mycobacterial cultures of CSF.
* Adjunct therapy: Dexamethasone (12–16 mg/d tapered over 6 weeks) for HIV-negative patients.
50
Historical clue of C. meomorfans, H. capsulatum, C. immitis
* MC: C. neoformans - soil and bird excreta
* H. capsulatum: Ohio and Mississippi River valleys of central US and central and south america
* C. immitis: Desert areas
51
Most important pathogen of brain abscess for immunocompotent host
* Streptococcus spp (anaerobic, aerobic and viridans 40%)
* Enterobacteriaceae (Proteus spp, E coli, KPN 25%)
* Anaerobes (Bacteroides spp, Fusobacterium spp 30%)
* Staphylococci - 10%
* IMMUNOCOMPROMISED HOST
* HIV, Transplant patient, Cancer, Immunosuppressed
* Nocardia, Toxoplasma gondii, Candida and C. neoformans
52
What stage of brain abscess presents with perivascular infiltration of inflammatory cells, surrounds a central core of coagulative necrosis and marked edema?
Early Cerebritis
Presents within day 1-3
53
What stage of brain abscess presents with pus formation --> enlargement of the necrotic center, surrounded by inflammatory infiltrate of macrophages and fibroblast?
Late cerebritis (D 4-9)
More distinct edema
thin capsule of fibroblasts and reticular fibers gradually develops, and the surrounding area of cerebral edema becomes more distinct
54
What stage of brain abscess presents with formation of a capsule and shows ring enlargement of MRI?
Early capsule formation (D 10-13)
55
What stage of brain abscess presents well-formed necrotic center surrounded by a dense collagenous capsule?
Late capsule formation (Day 14 and beyond)
* Marked glosis --> may contribute to seizure
56
Classic triad of brain abscess?
Headache, Fever, Focal Neurologic deficit
* Hemiparesis (frontal)
* Aphasia (dysphasia) or visual field defects (upper homonymous quandrantinopia (Temporal)
* Nystagmus and ataxia: Cerebellar
* Increased ICP: Cerebellum
57
Optimal therapy of brain abscesses?
High Dose Parenteral antibiotics + Neurosurgical drainage
IMMUNOCOMPETENT COMMUNITY ACQUIRED
Third- or fourth- generation cephalosporin and Metronidazole
For PENETRATING HEAD TRAUMA / RECENT NEUROSURGICAL PROCEDURE
* Ceftazidime / Meropenem for P. aeruginosa
* PLUS Vancomycin for staph
58
Indication of doing craniotomy or craniectomy in patient with brian abscess (2)?
Multiloculated abscesses
Unsuccessful stereotactic aspiration
59
Indication of medical therapy only on patients with brain abscess (4) and how long should parenteral antibiotic therapy given?
1. For neurologically inaccessible
2. Small <2-3cm or Nonencapsulated abscesses- cerebritis
3. Too tenuous to allow performance of a neurosurgical procedure
Minimum of 6-8 weeks of parenteral antibiotic therapy
60
How long should prophylactic anticonvulsant therapy be given to patients with brain abscess?
Continued for 3 months after resolution of abscess - withdrawal based on EEG
* NORMAL- slowly withdrawn
* Repeat EEG after medications were discontinued
61
Indication of glucocorticoid therapy (Dexamethasone 10mg IV every 6 hours) in brain abscess (3)?
Substantial periabscess edema
Mass effect
Increased ICP
62
How to document resolution of brain abscess?
SERIAL MRI/CT SCANS -
* once or twice monthly
* If antibiotic therapy alone: More frequent studies
63
What is the most common manifestation of neurocysticercosis?
New-onset partial seizures with/without secondary generalization
64
Stages of neurocysticerrcosis based on MRI/CT findings?
1. Vesicular Stage:
* Cystic lesions with scolex visible within cyst
* No significant surrounding edema.
2. Colloidal Stage:
* Peripheral enhancement with post-contrast imaging
* Substantial surrounding edema on T2 images.
3. Granulonodular Stage:
* Homogenous enhancement on postcontrast imaging.
* No surrounding edema on FLAIR images.
4. Nodular Calcified-Stage:
* Parenchymal brain calcifications, most common finding and evidence that the parasite is no longer viable - Best detected on CT; small calcifications detected by SWI on MRI.
65
Mmost common finding and evidence that the parasite is no longer viable on imaging
Parenchymal brain calcifications
Nodular-Calcified stage
66
Recommended test for all patients suspected with neurocysticercosis?
Funduscopic exam
67
Most common source of liver abscess infection?
Disease of the biliary tract: MC source
Common isolates: Enteric gram-negative aerobic bacilli and enterococci
* Hematogenous or contiguous sites of infection: S. aureus or a streptococcal species- Streptococcus milleri group
68
Single most reliable lab findings of liver abscess
Elevated serum alkaline phosphatase
* Elevated serum alkaline phosphatase: single most reliable lab findings
* Bilirubin (50%), aminotransferase - AST (48%)
Imaging:
CXR
New elevation of right hemidiaphragm
Right basilar infiltrate
Right pleural effusion
69
Surgical indication for percutaneous drainage of liver abscess (6)
* (+) multiple, sizable abscesses
* Viscous abscess- plug the catheter
* Associated disease requiring surgery
* (+) yeast
* Communication with an untreated obstrcructed biliary tree
* Lack of clinical response to percutaneous drainage in 4-7 days
70
Treatment of candidal liver abscess
* Liposomal amphotericin B (3–5 mg/kg IV daily) or an echinocandin, with subsequent fluconazole therapy
* Fluconazole alone (6 mg/kg daily) may be used (Stable, susceptible organism)
71
What organisms require echocardiogram when cultures on blood?
1. S. sanguinis
2. S. gallolyticus
3. S. mutans
72
What is the organism most frequently isolated in splenic abscesses?
Streptoccus spp. (Most)
Followed by s. aureus
(Endocarditis)
73
Vaccination prior to splenectomy
1. Streptococcus pneumoniae
2. Haemophilus influenzae
3. Neisseria meningitidis
74
What is the treatment of choice for epididymitis caused by N. gonorrhoeae or C. trachomatis?
Ceftriaxone 500mg IM as a single dose followed by Doxycycline 100mg orally 2x a day for 10 days
75
Antifungal drug resistance is one of the hallmarks of infection with this organism
C. auris
Elevated minimal inhibitory concentrations (MICs) to all three major antifungal classes—azoles, echinocandins, and polyenes—resulting in limited treatment options
76
Factors that influence mortality risk of PCP (6)
1. Patient’s age
2. Degree of immunosuppression
3. Presence of preexisting lung disease
4. Low serum albumin level
5. Need for mechanical ventilation
6. Development of a pneumothorax.
77
The induction of vascular permeability and shock in dengue is increased with (6)
1. Presence or absence of enhancing and non-neutralizing antibodies
2. Age < 12
3. Female
4. White > Black
5. Nutritional status
6. Timing and sequence of infections
* Dangerous: Dengue virus 1 infection followed by dengue virus 2 infection vs dengue virus 4 infection followed by dengue virus 2 infection
78
Central to the pathogenesis of falciparum malaria (3)
1. Rosette: Infected RBCs adhere to uninfected RBC
2. Agglutination: Infected RBCs also adhere to infected RBCs
3. Cytoadherence
cytoadherence, rosetting, and agglutination
79
Best biochemical prognosticators in severe malaria?
Plasma concentrations of bicarbonate or lactate
80
Laboratory test generally accepted as the best indicator of the immediate state of immunologic competence of the patient with HIV infection
CD4+ T cell count
81
Preferred antibiotic therapy for patients with tetanus?
Metronidazole (400 mg rectally or 500 mg IV every 6 h for 7 days) is preferred for antibiotic therapy.
82
Hallmark feature of enteric fever
Variable fever and abdominal pain
83
What vaccines are not recommended if with history of allergic reaction to latex (2)
1. Serogroup B meningococcal
2. Hepatitis A
84
What vaccines are not recommended if with history of allergic reaction to gelatin or neomycin (3)
1. MMR
2. Varicella
3. Zoster
85
What vaccines are not recommended if with history of allergic reaction to yeast (2)?
1. HPV
2. Hepaitis B
86
Which trematode is associated with crayfish or crabs?
Paragonimus westermani
* Half-cooked fish: Chlonochis sinensis
87
What is the drug of choice for fascioliasis?
Triclabendazole
88
