Infectious Diseases (Infections) Flashcards
All CNS infections can lead to…
Seizures
CNS Infection symptoms: Stiff neck, photophobia, meningismus
Diagnosis: Meningitis
CNS Infection symptoms: Confusion
Diagnosis: Encephalitis
CNS infection symptoms: Focal neurological findings
Diagnosis: Abscess
What are the most common causes of meningitis?
Streptococcus pneumonia (60%) Group B Streptococci (14%) Haemophilus influenzae (7%) Neisseria meningitidis (15%) Listeria (2%)
What are the differences in presentation between Lyme disease and Rickettsia?
Lyme: Rash shaped like a target, joint pain, facial palsy, tick remembered in 20%
Rickettsia: Rash moves from arms/legs to trunk; tick remembered in 60%
What is the best initial and most accurate test for CNS infections?
Lumbar puncture
When would you expect to see a CSF evaluation with a cell count in the 1000s and the presence of neutrophils?
Bacterial meningitis
When is a head CT necessary prior to LP for CNS infections?
When there is a possibility that a space occupying lesion may cause herniation…
- Papilledema
- Seizures
- Focal neurological abnormalities
- Confusion interfering with neurological examination
What is the best course of action in treating CNS infection when there is a contraindication to immediate LP?
Give antibiotics
When is a bacterial antigen test indicated for CNS infection?
When the patient has received antibiotics prior to the LP and the culture may be falsely negative
What is the most accurate diagnostic test or the following…
Tuberculosis:
Lyme and Rickettsia:
Cryptococcus:
Tuberculosis: Acid fast stain and culture on 3 high volume lumbar punctures
Lyme and Rickettsia: Specific serologic testing, ELISA, western blot, PCR
Cryptococcus: India ink is 60-70% sensitive; Cryptococcal antigen is >95% sensitive and specific (culture is 100% specific)
What is the best initial treatment of bacterial meningitis?
When would you add Ampicillin?
Ceftriaxone, vancomycin and steroids
Add ampicillin if immunocompromised for listeria
Listeria is resistant to all ___________
cephalosporins
What are the risk factors for listeria (require addition of ampicillin to treatment)?
Elderly Neonates Steroid use AIDs or HIV Immunocompromised (including alcoholism) Pregnant
What is given to close contacts of patients with Neisseria meningitidis?
What is meant by “close contacts”
Rifampin, ciprofloxacin, or ceftriaxone
Close contacts: Those who have major respiratory fluid contact
What is the most common cause of encephalitis?
Herpes simplex
What is most accurate test of herpes encphalitis
PCR of CSF
What is the most common neurological deficit of untreated bacterial meningitis?
Eighth cranial nerve deficit or deafness
What is the best initial therapy for herpes encephalitis?
Acyclovir
What is used to treat acyclovir-resistant herpes?
Foscarnet
What is a dangerous side effect of acyclovir and foscarnet?
Renal toxicity because the medication precipitates in the renal tubules (foscarnet has more renal toxicity)
How does Otitis media present?
Redness, immobility, bulging, and a decreased light reflex of the tympanic membrane
What is the most sensitive physical finding for otitis media?
Immobility (fully mobile tympanic membrane essentially excludes otitis media)
What is the most accurate diagnostic test for otitis media?
Tympanocentesis for a sample of fluid for culture
When is tympanocentesis used in the diagnosis of otitis media?
Multiple recurrences or no response to multiple antibiotics
What is the best initial therapy for otitis media?
Amoxicillin
If amoxicillin is ineffective in treating otitis media, what else can be used/added?
Amoxicillin/clavulanate
Azithromycin, clarithromycin
Cefuroxime, loracarbef
Levofloxacin, gemifloxacin, moxifloxacin (contraindicated in children)
What is the most accurate diagnostic test for sinusitis?
Sinus biopsy or aspirate
When is a biopsy needed for sinusitis?
Infection frequently recurs
There is no response to different empiric therapies
What is the presentation of sinusitis?
Facial pain, discolored nasal discharge, bad taste in mouth, and fever
What are the first-line therapies for both otitis and sinusitis?
Amoxicillin/clavulinic acid, doxycycline, and TMP/SMX
a decongestant is also used to promote sinus drainage
How does pharyngitis present?
Pain on swallowing Enlarged lymph node in the neck Exudate in the pharynx Fever No cough and no hoarseness
What is the best initial test for pharyngitis?
Rapid strep test
What type of pharyngitis produces a positive rapid strep test?
What type presents with small vesicles or ulcers?
Membranous exudates?
Rapid strep test: Group A beta hemolytic streptococci
Small vesicles/ulcers: HSV or herpangina
Exudates: Diptheria, vincent angina, or EBV
How is pharyngitis treated?
Penicillin or amoxicillin is the best initial therapy
How is pharyngitis treated in penicillin allergic patients (2 answers depending on type of allergic reaction)?
Cephalexin if the reaction is only a rash
Clindamycin or a macrolide if allergy is anaphylaxis
How does influenza present?
Arthralgias/myalgias Cough Fever Headache and sore throat Nausea, vomiting, or diarrhea (especially in children)
What are the treatment regulations for influenza?
Less than 48 hours of symptoms: Oseltamivir, zanamivir; neuraminidase inhibitors shorten duration of symptoms
More than 48 hours: Symptomatic treatment only
