Infectious Disease Flashcards
A patient was bit by the Aedes mosquito and now has symmetric polyarthralgias, a maculopapular rash on the limbs and trunks, peripheral edema and cervical lymphadenopathy. What lab abnormalities would you expect to see in this patient?
Thrombocytopenia and lymphopenia are commonly seen in people with Chickungunya fever.
Locations where patients are at risk for babesiosis
Northeast and midwest U.S.
Patient has salmon rose colored spots and bradycardia
Typhoid fever
Most rapid and sensitive way to diagnose disseminated histoplasmosis
Urine or serum immunoassay
Features of disseminated histoplasmosis
Reticuloendothelial invasion resulting in pancytopenia, hepatosplenomegaly and adenopathy.
Treatment of disseminated histoplasmosis
Mild-moderate disease = itraconazole
Severe disease = IV amphoB x 2 weeks followed by itraconazole for 1 year
Tick that transmits babesia and lyme disease
Ixodes
Treatment of babesiosis
Atovaquone-azithromycin or quinine-clindamycin
Frequent cause of osteomyelitis in adults with nail puncture wound
Pseudomonas
Endocarditis with what organism raises suspicion for colon cancer?
S. gallolyticus (S. bovis I)
RMSF CSF analysis
Similar to viral meningitis: WBC
Classic triad seen in splenic abscess? Most common offending organisms?
Fever, leukocytosis and LUQ pain. Bugs = staph, strep and salmonella.
Most common cause of splenic abscess? Treatment?
Infective endocarditis. Treat with splenectomy.
Bacteria that may cause an increase in urinary pH?
Those that produce urea: proteus, klebsiella, morganella, pseudomonas, providencia, staph and ureaplasma.
Preferred HIV screening test
4th gen assay that detects anti-HIV antibodies and p24 antigen. If positive, this should be followed up with HIV-1/HIV-2 antibody differentiation immunoassay. Plasma HIV RNA testing is done if initial screen is negative and suspicion remains high.
HCV screening recommendations
Elevated ALT, HIV positive, IVDU, clotting factors before 1987, blood transfusion before 1992, dialysis or born between 1945-1965.
Gonorrhea screening recommendations
Women sexually active before 25, irregular condom use, multiple partners, STD history or pregnancy.
Syphilis screening recommendations
Pregnancy, MSM, other STD, prostitutes and incarceration.
Effectiveness of rimantadine and amantadine
Only against influenza A
MRI findings in patients with progressive multifocal leukencephalopathy
Multiple demyelinating and non-enhancing lesions
Ring enhancing brain lesions in patients with HIV
Toxo (multiple), primary CNS lymphoma (single)
AIDS dementia complex MRI findings
Cortical atrophy and ventricular enlargement
Treatment of norcardia
TMP-SMX. Add carbapenems if the brain is involved.
Hematologic complication associated with infectious mononucleosis
Autoimmune hemolytic anemia associated with anti-EBV IgM (cold agglutinins) cross reacting with RBCs and platelets, leading to complement-mediated RBC destruction. This typically occurs 2-3 weeks after symptoms arise.
Definition of fulminant hepatic failure
Encephalopathy that develops within 8 weeks of onset of acute liver failure. Typically seen in acetaminophen overuse, Hep B/D, EtOH and meth use.
Contraindications to liver transplant
Irreversible cardiopulmonary disease, incurable malignancy, recent (
Treatment of choice for patients with cellulitis and systemic signs
IV nafcillin or cefazolin. Vancomycin if high MRSA prevalence.
Blood cultures in patients with disseminated gonococcemia?
Typically negative due to its fastidious nature. This is why you diagnose with NAAT.
Treatment of disseminated gonococcal infection?
IV ceftriaxone 1g/day 7-14 days, switch to PO.
Empiric PO azithromycin or doxycycline for concomitant chlamydia infection.
Extra pulmonary manifestations of blastomycosis
Bone, skin and prostate
Treatment of lyme disease
Doxy in patients ≥ 8 years old because it also covers anaplasma
Amoxicillin or cefuroxime if
Ipsilateral CN VII paralysis, ear pain and vesicles in the EAC and external ear.
Ramsay-Hunt syndrome due to HSV
Treatment of cryptococcal meningitis
IV amphoB + flucytosine for 2 weeks. Fluconazole for 8 more weeks. You can try intrathecal amphoB if initial therapy fails.
Empiric therapy for bacterial meningitis
IV ceftriaxone and vancomycin (add ampicillin to cover legionella if > 50 years old)
Common side effects of the following HIV drugs:
Didanosine
Abacavir
All NRTIs
All NNRTIs
Nevirapine
Didanosine - pancreatitis
Abacavir - crystal-induced nephropathy
NRTIs - lactic acidosis
NNRTIs - SJS
Nevirapine - liver failure
Management of early necrotizing skin infection
Parenteral antibiotics and early surgical exploration
Management of herpes zoster infection to reduce likelihood of post-herpetic neuralgia
Acyclovir + TCA
Preferred treatment of onychomycosis and dermatophytosis
Griseofulvin
When should you start anti-retroviral therapy for patients with cryptococcal meningitis?
2-8 weeks after completing induction therapy to avoid risk of immune reconstitution syndrome
Preferred treatment for cerebral toxoplasmosis
Sulfadiazine-pyrimethamine
Who gets the meningococcal vaccine?
Age 11-12 (13-18 if not previously vaccinated)
Optional at 19-21 (do if high-risk)
Booster at 16-21 (if primary received b/f 16)
Treatment of invasive mucormycosis
Surgical debridement + IV amphoB
Immunocompromised patient with fever, hemoptysis, cavitary lesion on CXR and pulmonary nodules with halo sign and lesions with air crescent on CT.
Invasive aspergillus
Definition of neutropenia. Management of patients with febrile neutropenia?
ANC
Post-exposure prophylaxis for healthcare workers exposed to HBV
HBV vaccine and HBIG within 12 hours if inadequate vaccination.
No treatment if adequate vaccination
Vaccinating patients undergoing splenectomy
≥ 14 days before schedule splenectomy or > 14 days after splenectomy with pneumococcal, meningococcal, H. flu, influenza, HAV, HBV and TDaP vaccines.
Factors that differentiate acute HIV infection from infectious mononucleosis
Painful mucocutaneous ulcerations, skin rash and prolonged diarrhea are more common in HIV. Tonsillar exudates are more common in mono.
Lab values that will tip you off to vertebral osteomyelitis
Leukocyte count may be normal, but ESR and CRP are always elevated.
Factors that differentiate CMV mono from EBV mono
CMV typically does not have pharyngitis, cervical lymphadenopathy and mono spot will be negative but the patient will still have atypical lymphocytes.
Management of hepatic hydatid cyst
Surgical resection + albendazole
Indications for addition of corticosteroids to TMP-SMX in patients with PCP pneumonia
PaO2 35 on room air
Alternative agents to TMP-SMX in patients with PCP pneumonia
Mild-moderate disease: TMP-dapsone, primaquine-clindamycin and atovaqone.
Severe: pentamidine or primaquine + IV clindamycin.
Diagnosis and treatment of amebic liver abscess
Diagnose with E. histolytic serology as stool microscopy may be negative by the time liver abscess forms. Treat with metronidazole to get rid of the abscess and a luminal agent like paromomycin to eradicate intestinal parasites.
Ludwig’s angina
Infection of the molars that extends to the submandibular and sublingual glands with high risk of asphyxiation due to tongue elevation.
In addition to antibiotics, what should you give adults with suspected bacterial meningitis?
Dexamethasone x 4 days
Difference between complicated and uncomplicated pyelonephritis? Treatment?
Complicated = patients typically have urinary symptoms despite abx therapy for 48-72 hours due to renal abscess, emphysematous pyelonephritis or papillary necrosis. They often have a history of DM, nephrolithiasis, immunosuppression and abnormal urinary anatomy. Mild-mod = IV ceftriaxone, fluoroquinolone or cefepime Severe = amp-sulbactam, ticarcillin-clav, pip-tazo, meropenem, imipenem, aztreonam +/- gent
Uncomplicated: cystitis, flank pain, fever, positive urine and blood cultures that resolve with empiric IV fluoroquinolones and IV fluids. Typically no imaging is required in these patients.
Mild-mod = po fluoroquinolones (cipro) or TMP-SMX
Severe = IV ceftriaxone, fluoroquinolones or TMP-SMX
If pregnant = ceftriaxone +/- gentamicin, aztreonam
Time period of heterophile antibody positivity in patients with infectious mono
2 weeks to 1 year
Most common manifestation of norcardia
Pulmonary nodules
Who gets treated for HBV and what are the options?
People in liver failure, have complications of cirrhosis, immunosuppressed and those with +HBeAg, HBV DNA > 20k, ALT > 2x upper limit of normal get treated. Options include:
IFN-alpha for younger patients with compensated liver failure.
Lamivudine for HIV patients, but role is diminishing due to resistance.
Entecavir for decompensated cirrhotics
Tenofovir is preferred overall and is the strongest drug with minimal resistance
Medical management of patients with chronic HCV infection
Pegylated IFN + ribavirin + telaprevir (if genotype 1 HCV)
C. difficile toxins
Enterotoxin A: causes watery diarrhea
Cytotoxin B: causes epithelial necrosis and fibrin deposition
Antibiotics most commonly implicated in C. difficile colitis
Fluoroquinolones, penicillins, cephalosporins and clindamycin
Stages of Tb infection
The bacilli, macrophages and PMNs replicate in alveolar air space to form a tubercle (Ghon complex). Cell-mediated destruction results in a granuloma and latent Tb. In periods of immunosuppression, bacilli in the granuloma proliferate in lung apices and cause infiltration and cavitation on CXR.
Treatment of patients infected by anaerobic gram positive branching filamentous organism that may not grow on culture for ~ 3 weeks.
Actinomyces is treated with high dose PCN x 12 weeks. Clindamycin is an alternate if PCN allergic.
Diagnosing cryptococcal meningitis
1) Neuroimaging to rule out mass, if no mass, do LP.
CSF antigen testing
India ink stain
Culture on Sabouraud’s agar
Tick that transmits disease in patients from the southeast/ southcentral U.S. who have acute febrile illness with malaise, confusion and rash in
Amblyomma americanum (lone star tick) transmits ehrlichiosis. Lab findings may include leukopenia, transaminitis and thrombocytopenia.
Diagnose with intracytoplasmic morulae on monocytes and/or PCR.
Treat empirically with doxy while awaiting diagnostic test results.
Next step if a patient on isoniazid presents with mildly elevated liver enzymes.
Observation, this typically resolves after the first few weeks of treatment.
Patient rapidly decompensated after administration of oral corticosteroids for treatment of presumed sarcoidosis, what should’ve been done 1st?
Untreated Tb, histoplasmosis or coccidioidomycosis can mimic non-caseating granulomas seen in sarcoid. This patient should’ve had testing prior to steroid treatment.
Prophylactic regimen for HIV patients with PPD > 5mm
INH x 9 months with pyridoxine and periodic LFT checks.
Most common pathogen involved in young children with CF?
S. aureus. Consequently young kids with CF and severe pneumonia should be given vancomycin.
Most common causes of bacterial meningitis in kids > 1 month old? How do you treat?
S. pneumo and N. meningitides. 1st LP, then give ceftriaxone + vancomycin. Add dexamethasone to reduce risk of hearing loss, especially if Hib is involved.
Why use cefotaxime for bacterial meningitis empiric therapy in neonates?
Ceftriaxone displaces bilirubin from albumin and increases risk for kernicterus.
1st line drug for acute bacterial sinusitis
Amoxicillin + clavulanic acid
Most common pulmonary pathogens in CF
S. aureus (infants and young children), P. aeruginosa (adolescents and adults), Hib and S. pneumoniae (all patients)
Treatment of patients with acute rheumatic fever but no signs of pharyngitis
Still give PCN G to reduce further cardiac damage. Give steroids if chorea is present. Give NSAIDs if carditis is present.
Most common pathogen seen in acute bacterial lymphadenitis in kids
S. aureus
Diagnosing pertussis? Treat?
PCR and lymphocyte predominate leukocytosis. Treat with macrolides.
Triad of HUS
Thrombocytopenia, hemolytic anemia (MAHA) and uremia
Labs that suggest lactose intolerance
Acidic stool pH, reducing sugars present and positive H+ breath test
Baby is born with:
A) HSM, hydrocephalus, chorioretinitis and intracranial calcifications
B) SNHL, cataracts, HSM, heart defects, microcephaly and TTP
C) HSM, IUGR, petechiae/purpura, microcephaly, SNHL and periventricular calcifications
D) HSM, jaundice, anemia and lesions on palms and soles
A) Toxo
B) Rubella
C) CMV
D) Syphilis
Centor criteria
Only valid in adults and adolescents, not kids
- Fever
- Anterior cervical LAD
- Tonsillar exudates
- No cough
RAST if ≥2. May skip RAST and treat if 4.
Empiric therapy for acute unilateral lymphadenitis in kids
Clindamycin
Treatment for pinworm infection
Mebendazole
