Infectious Disease Flashcards
a healthy individual must have a PPD over what size limit to be considered positive
greater than or equal to 15mm
which patients are considered to have a positive PPD when it is greater than or equal to 5mm
HIV, immunocompromised, known recent TB exposure/contact
which patients are considered to have positive PPD when it is greater than or equal to 10mm
living in high risk areas (
major contraindications to rotavirus vaccine
SCID, history of intussisception, congenital malformations of GI tract (Meckel’s), anaphylaxis to vaccine contents
how do you treat a pregnant woman for lyme disease
oral amoxicillin (doxycycline contraindicated due to teratogenicity, skeletal abnormalities and teeth discoloration)
treatment of cellulitis with systemic signs?
nafcillin or cefazolin
multiple ring enhancing lesions with edema seen in the brain of a patient with HIV is ___________
what is the treatment?
toxoplasmosis; treat with sulfadiazine-pyrimethamine
what are the main symptoms of infection with Bordatella pertusis, how is diagnosis confirmed and what is the treatment
starts with cough and rhinorrhea, eventually becomes “100 day cough” with coughing fits and posttussive emesis, inspiratory whoop, can cause apnea in infants, subconjunctival hemorrhages; confirm with culture or PCR; treat with macrolides
when a rapid-onset gastroenteritis follows ingestion of meat or mayonnaise-containing foods (potato salad, tuna salad) what organism should you suspect
staph aureus (preformed toxin causes rapid onset)
treatment of choice for uncomplicated Lyme disease in age > 8 years vs. age
oral amoxicillin or cefuroxime for age 8 years
what is the classic triad of congenital rubella
leukocoria (white pupillary reflex from cataracts), patent ductus arteriosus, sensorineural deafness
name two common organisms that cause pneumonia in cystic fibrosis patients and which is more common in children vs. adults
staph aureus (more common in children) and pseudomonas (more common adults)
what fungal disease do cystic fibrosis patients get
aspergillus
what is the classic triad of congenital toxoplasmosis
chorioretinitis, hydrocephalus, intracranial calcifications (can also cause microcephaly, hepatosplenomegaly and thrombocytopenia)
which childhood infection commonly causes leukopenia
measles (rubeola) causes leukopenia via a T-cell cytopenia
what vitamin is beneficial for reducing morbidity and mortality in measles
vitamin A decreases morbidity and mortality in measles via immune enhancement and GI/respiratory epithelium regeneration
ring-enhancing lesions in an HIV patient should make you think these two things…
toxoplasmosis and CNS lymphoma
what is the prophylaxis for toxoplasma and when would you administer it
prophylactic bactrim is given to HIV patients with AIDS who have positive antibodies to toxo because reactivation is common
should you vaccinate an HCV infected pregnant woman against HBV and HAV?
Yes. The inactivated vaccines against HBV and HAV are safe in pregnancy
how can you differentiate between fungal (Candida) and viral (CMV, HSV) esophagitis based on presentation?
Candida esophagitis usually involves thrush and has mild to no odynophagia
Viral esophagitis usually involves severe odynophagia and does not have thrush
what does kaposi’s sarcoma look like
pink, red, brown or purple plaques or globular growths with high vascularity
what two organisms cause painful genital ulcers and how can you differentiate them on physical exam
HSV and H. ducreyi (chancroid): HSV ulcers have a shallow, erythematous base, chancroid tends to have a friable, exudative base
what three organisms cause painless genital ulcers
chlamydia, primary syphilis, klebsiella granlumatis (granuloma inguinale)
what hematologic complications are associated with EBV infectious mononucleosis
- cold autoimmune hemolytic anemia (due to cross-reactivity with red blood cells and platelets leading to complement-mediated RBC and platelet destruction)
- Burkitt/Hodgkin’s lymphoma
a patient infected with a hydatid cyst in the liver or lung (round, fluid filled cyst with daughter cysts) was probably infected by what organism and how
Echinococcus granulosus
via sheep or dog exposure
infectious endocarditis in a patient with recent UTI is likely due to what organism
Enterococci
how does one contract Q fever (Coxiella burnetti)
inhaled aerosols from livestock or unpasturized milk
a patient with sudden, continuous writhing and jerked movements in addition to pericarditis and nodules on hands should make you think of what condition and what organism
acute rhematic fever (JONES: joint pain, carditis, nodules, erythema marginatum, sydenham’s chorea)
caused by strep pyogenes
what is the most common infectious cause of bloody diarrhea in an afebrile patient
enterohemorrhagic E. coli
how should enterohemorrhagic E. coli be treated
supportive; NO abx because they aren’t helpful and can increase the risk of HUS
what is the best way to test for histoplasmosis
urine or serum antigen (fastest and very sensitive and specific)
what is the treatment for disseminated histoplasmosis if severe vs. not severe
severe: amphotericin B for 2 weeks, then itraconazole
non-severe: itraconazole
(NOT fluconazole due to poor coverage)
pulmonary infiltrates showing partially acid-fast, gram positive filamentous branching rods is likely what organism?
how is it treated?
Nocardia
treat with bactrim
how are actinomyces and nocardia similar and different
both are filamentous gram positive rods
Actinomyces is anaerobic, not acid-fast and contains sulfur granules
Nocardia is aerobic, partially acid-fast
how is pertussis infection confirmed
pertussis culture or PCR
what is the treatment for cervicofacial actinomycosis
penicillin (use clinda if allergic)
what is the treatment for pinworm (enterobius vermicularis)
albendazole or pyrantel pamoate
how can you differentiate between measles and rubella (german measles)
measles tends to have a high-grade fever and Koplik spots
rubella has a low-grade fever and lymphadenopathy and Forschheimer spots
what should a patient do if he/she finds a tick attached to the skin
remove ASAP via tweezers grasped as close to skin as possible and with upward pressure applied
what four things allow you to distinguish orbital cellulitis from preseptal cellulitis?
- opthalmoplegia (eye pain)
- pain with extraocular muscle movements
- vision impairment
- proptosis (protrusion of eyeball)
renal dysfunction, thrombocytopenia and anemia after a diarrheal illness is likely what (and what organism is implicated)
Hemolytic uremic syndrome
enterohemorrhagic E. coli, O157:H7
what criteria should you use to determine whether to perform a rapid strep test
2 or more Centor criteria
- tonsillar exudates
- fever
- tender cervical adenopathy
- absence of cough
what are the most common causes of acute bacterial rhinosinusitis and what is the treatment of choice
Step pneumo and nontypable H. influenzae (Moraxella catarrhalis less commonly)
treat with amoxicillin-clavulanate (due to beta-lactamase resistance)
what are 3 ways to clinically diagnose acute bacterial rhinosinusitis
- 10 or more days of persistent symptoms without improvement
- severe symptoms (high fever, purulent nasal discharge, facial tenderness)
- onset of symptoms 5 or more days after an improving URI
what are the three main drugs you can use to treat HBV
- interferon alpha (not for decompensated cirrhotics)
- entecavir
- tenofovir
(lamivudine is less favored now due to resistance)
how can you tell the difference between CMV esophagitis and HSV esophagitis on endoscopy
CMV esophagitis produces linear ulcers
HSV esophagitis produces round ulcers and vesicles
what antibiotics are used to treat septic arthritis (after joint aspiration and cultures return of course)
3 months: nafcillin, vanc, cefazolin, clindamycin
what is the treatment of PCP?
what should you add if the disease is severe (PaO2 35)?
bactrim
add steroids if severe to reduce inflammation
which species of strep most commonly causes infective endocarditis in patients with prosthetic valves or catheters, etc.
Strep epidermidis
what are the characteristic symptoms of croup and what organism causes croup
barky cough, whistling sound on inspiration
parainfluenza causes croup
what antibiotics are given for acute bacterial meningitis for:
- ages 2-50
- ages > 50
- immunocompromised
- skull injury/surgery
-ages 2-50: vancomycin (pneumococcus) + 3rd gen cephalosporin (meningococcus)
-ages > 50: vanc + 3rd gen cephalosporin + add ampicillin for Listeria
-immunocompromised: vanc + cefepime + ampicillin
-skull injury: vanc + cefepime
note steroids should be started in adults and continued if cx comes back as pneumococcus
eggshell calcifications of a liver cyst suggest what organism and what potential sources
Echinoccocus granulosus; contracted from dogs or sheep
what is the treatment for cat scratch disease
5 days of azithromycin to clear Bartonella henselae
which antibiotic should you use for pneumonia occurring after an endoscopic procedure
clindamycin (for suspected anaerobes in aspiration pneumonia)
how do you differentiate between gonococcal and chlamydial conjunctivitis and how are each treated
gonococcal: profuse mucopurulent discharge, marked eyelid swelling and corneal ulceration; ppx with topical erythromycin and treat with IV ceftriaxone or cefoxatime
chlamydial: scant watery, bloody or mucopurulent discharge, chemosis; treat with oral erythromycin
what organisms cause acute epididymitis
- in young men?
- in older men?
- young men: STDs (gonorrhea and chlamydia)
- older men: E.coli (most common), Pseudomonas (less common)
a flu-like illness, neurologic changes, thrombocytopenia, leukopenia, transaminitis and elevated LDH after a tick bite should make you think what organism?
how should you treat?
Erhlichiosis (lone star tick in Southern US)
treat with doxycycline
what antibiotics are good against Pseudomonas
pip/tazo, cefepime (4th gen), gentamicin, tobramycin, amikacin, imipenem/cilastin, aztreonam, ciprofloxacin
what are the characteristic symptoms of histoplasma capsulatum (and where is it endemic to)
- pulmonary granulomas (mimics sarcoidosis)
- mediastinal/hilar lymphadenopathy
- arthralgias
- erythema nodosum
Histoplasma capsulatum is endemic to Ohio/Mississippi river basins
how is histoplasma diagnosed
fungal stain/culture and urine antigen
what parts of the world have endemic chloroquine-resistant P. falciparum and what are the recommended prophylactic antimalarials?
southern and southeast Asia, sub-saharan Africa, Amazon
ppx: mefloquine (best in pregnancy), atovaquone-proguanil, doxycycline
what areas have more endemic P. ovale and vivax rather than falciparum?
what antimalarials can you use for ppx?
Korean peninsula, Mexico, parts of South America
ppx: primaquine
state the algorithm for working up suspected vertebral osteomyelitis
patient has fever, back pain and FOCAL spinal tenderness –> blood cx, ESR/CRP, plain x-ray
–> if ESR/CRP is elevated, but x-ray neg then get MRI –> CT-guided needle biopsy
what are the symptoms of acute HIV infection
mono-like syndrome (LAD, fever, night sweats, sore throat, arthralgias); generalized macular rash; GI symptoms (diarrhea, abdominal pain)
what is the appropriate prophylaxis for household members of a pertussis infected person
macrolid ppx for all household contacts (regardless of vaccination status) as pertussis is highly contagious (note, only azithromycin for infants
a unilateral cervical lymphadenitis (swelling, erythema and warmth of the node) is most likely caused by what organism
staph aureus is the most common cause of cervical lymphadenitis
vulvar pruritus in a young child which is experienced mostly at night is suspicious for what organism
pinworm (enterobius vermicularis) can occur as anal pruritus or vulvovaginitis
what can be used to distinguish EBV mononucleosis from Group A strep pharyngitis
EBV has diffuse cervical lymphadenopathy while GAS has anterior cervical chain LAD
if a patient is treated with amoxicillin, and soon after develops a maculopapular rash then the infection is likely EBV instead
why shouldn’t ASO antistreptolysin antibodies be tested in acute pharyngitis
ASO titers peak ~1 month after streptococcal infection so they aren’t useful in acute pharyngitis
meningococcus vaccine and booster is especially important to what populations
soldier’s living quarters, travel to sub-Saharan desert
when should meningicoccus vaccine be given (initial dose, booster and special considerations)
all children 11-12, or 13-18 if missed give booster for ages 16-21 optional for ages 19-21 give to high risk adults >21 high risk= military, college, sub-saharan Africa
what are the symptoms of a necrotizing surgical infection and how do you treat it
sx: intense pain, edema or erythema beyond/around the site; parasthesia or anesthesia at the wound edges; cloudy grey drainage (“dishwater drainage”); fever, hypotension or tachycardia; subcutaneous gas or crepitus
Tx: parenteral abx and surgical exploration for debridement
what are the sx; dx method and tx of babesiosis
sx: fever, hemolytic anemia (jaundice, hemoglobinuria, renal failure) after tick bite in northeastern US
dx with Giemsa thin and thick blood smear
tx: atovaquone-azithromycin or quinine-clindamycin
a patient on isoniazid develops mild elevations in AST and ALT (
nothing! observe and continue to monitor LFT’s; isoniazid can cause a mild subclinical hepatic injury in young, healthy pts. that is self-limited
presentation of epiglotitis?
abrupt onset fever, sore throat, dysphagia, drooling, relief with hyperextension of the neck, eventually dyspnea, sometimes stridor
pumonary nodules with halo sign or air crescent is likely
invasive aspergillosis
A child with meningitis suddenly develops hypotension and dies. What is the likely cause of death and its pathophysiology?
Waterhouse-Friederichsen syndrome is associated with meningococcal meningitis; it is caused by adrenal gland hemorrhage
what is the difference between symptoms and treatment of echinoccocus and entamoeba
both cause liver cysts: echinococcus generally has no fever and is commonly asymptomatic, while entamoeba causes dysuntery and fever
Tx for echinococcus=bendazole and aspiration
Tx for entamoeba=oral metronidazole (usually no drainage needed)
maculopapular rash involving the palms and soles along with generalized lymphadenopathy should make you think of what condition
secondary syphilis
a post-bone marrow transplant patient with lung infiltrates and diarrhea should make you think of what organism
CMV pneumonitis and colitis
what is erythema multiform and what causes it
multiple small target-shaped lesions all over the body that can become confluent; caused by drug reaction, mycoplasma or herpes
what is the presentation of chikunguya
fever, malaise, lymphadenopathy, symmetric polyarthralgias, thrombocytopenia and leukocytopenia in a patient who was recently in the Caribbean
which HIV patients should not receive live vaccines
patients with AIDS (CD4
what is erysipelas? what is the associated organism?
a type of cellulitis involving the superficial dermis (vs. deep dermis of cellulitis) characterized by sharp demarcation and prominent swelling of the erythematous area; commonly caused by Group A Strep
how do you treat bullous vs. non-bullous impetigo
bullous: oral cephalexin, dicloxacillin or clindamycin
non-bullous: topical mupirocin
what three situations predispose to toxic shock syndrome
nasal packing, tampon use, and surgical packing
what are some characteristic features of dengue fever
fever, myalgia, arthralgia, headaches, retro-orbital pain, leukopenia
how should you address a minor cat bite
treat with prophylactic amox/clavulanate for 5 days (cat bites are usually deep, despite cleanliness and Pasturella is a feared complication)
crystal induced nephropathy is a complication of which antiretroviral
indinavir (a protease inhibitor)
Think “Crystals from India”
which antiretrovirals are known to cause lactic acidosis
NRTI’s
which antiretrovirals are known to cause Steven-Johnson Syndrome
N-NRTI’s
which antiretroviral is associated with liver failure
nevirapine
swelling, tenderness and crepitus in the submandibular and sublingual spaces is what condition and how is it acquired
Ludwig angina: cellulitis of the submandibular and sublingual glands; acquired from tooth (molar) infection that spreads to submandibular and sublingual spaces; usually strep or oral anaerobes
what is the treatment for acute unilateral cervical adenitits
clindamycin (covers the most common causes=strep and staph aureus)
what is the side effect of giving an infant oral erythromycin
pyloric stenosis
a neonate with a staccato cough likely has what infection and what is the treatment
chlamydial pneumonia; treat with oral erythromycin
most common cause of viral meningitis
enteroviruses like echovirus and coxsackie
what are the symptoms and treatment of nocardiosis
pulmonary nodules and symptoms resembling TB, CNS involvement, skin rash
Tx=bactrim (+ a penem or linezolid if severe)
bilateral parotid enlargement and fever/malaise in an unvaccinated child should make you think of what disease and what other organ is commonly affected
mumps parotitis
also affects the testes: mumps orchitits
can also cause aseptic meningitis and encephalitis
what is the treatment for latent TB (positive PPD with negative CXR and no sx)
INH + pyridoxine for 9 months (alternative = INH for 6 months or rifampin for 4 months)
what is the treatment of choice for a human bite
amoxicillin-clavulanate
a patient being treated for syphilis suddenly develops worsening of symptoms; what is the reason?
Jarish-Herxheimer reaction: rapid death of spirochetes leads to release of antibody-antigen complexes and massive immunologic reaction
fever, cough, diarrhea, night sweats, hepatosplenomegaly and alkaline phosphatase elevation in an HIV patient with CD4
disseminated Mycobacterium avium complex
when a patient who is sick with a respiratory infection suddenly develops subcutaneous crepitus what test must you order right away
and emergent CXR for possible pneumothorax
what are the neurologic complications of AIDS (mnemonic and causative organisms)?
DREAM=dementia (HIV), retinitis (CMV), encephalopathy (PML from JC virus), abscess (toxoplasma), meningitis (cryptococcus)
increased intracranial pressure (papilledema) is characteristic of what AIDS-associated infection
cryptococcus neoformans meningitis (cryptococci occlude CSF flow leading to increased intracranial pressure)
in a patient with croup whose respiratory status is deteriorating what should your first intervention be? then after that fails?
racemic epinephrine;
if epi fails then intubate (note: starting racemic epinephrine can decrease rates of intubation)
a diabetic develops necrotizing infection of the nasal turbinates and periorbital space with chemosis and proptosis; what is the organism and treatment
mucormycosis due to rhizopus
Tx: surgical debridement and amphotericin B
pneumonia in diabetics and alcoholic and with current jelly sputum is likely what organism
klebsiella pneumoniae
LUQ pain, leukocytosis, splenomegaly and splenic fluid collection suggests what condition and how is it acquired
splenic abscess; can be caused by left-sided infective endocarditis (septic emboli to spleen), immunosuppression, IVDU, trauma, hemoglobinopathies
explain post-exposure prophylaxis for chicken pox
immunocompetent, unvaccinated: VZ vaccine
immunosuppressed, unvaccinated: VZ immunoglobulin
vaccinated: observation
in an HIV patient what is the difference in terms of presentation between PJP pneumonia and pneumococcus pneumonia (most common cause of pneumonia in HIV patients)
PJP pneumonia presents as dry cough and dyspnea with diffuse bilateral infiltrates on CXR; pneumococcus presents with high fever, productive cough, pleural effusion and unilateral consolidated infiltrate on CXR
erysipelas is most commonly caused by what organism
Group A strep
