Microbiology Flashcards
CMV: Pharmacology
What is the MOA of Foscarnet?
It directly inhibits both DNA polymerase in HSV and reverse transcriptase in HIV. It is a pyrophosphate analog that does not require intracellular activation.
Uworld Pharmacology: Lyme disease
How do you treat Lyme disease?
Doxycycline or PCN-type abx (eg, ceftriaxone). Tx with ceftriaxone during the second, early disseminated phase, can prevent Late Lyme disease.
Uworld Microbiology: Lyme disease
What organism causes Lyme disease, how is transmitted, where is it considered endemic?
Caused by the spirochete Borrelia burgdorferi, transmitted by the bite of an Ixodes tick. Endemic in the northeastern USA and Northern Europe.
Uworld Pathophysiology: Lyme disease
Describe the series of phases in Lyme disease:
- Early localized phase: Days to wks following exposure, patients experience flu-like symptoms and the characteristic cutaneous eruption, erythema chronic migraines (ECM- target lesion)
- Early disseminated phase: Weeks or months later, there may be CNS (eg, facial palsy) and/or cardiac involvement (eg, AV Nodal Block)
- Late Lyme disease: Occurring months to years post-exposure, is rare given abx for other indications. Asymmetric arthritis (mc single knee joint) and/or subacute encephalopathy with decreased memory, somnolence, and mood changes.
Uworld: Toxoplasmosis encephalitis
Describe the setting of Toxoplasma encephalitis:
- exposure to cat feces with subsequent ingestion of Toxoplasma Gondii
- Reactivation in setting of immunosuppression
- Primarily AIDS with CD4 count < 100/mm^3
Uworld: Toxoplasmosis encephalitis
Describe the clinical manifestations of Toxoplasma encephalitis:
- headache
- confusion
- fever
- focal neurological deficits/seizures
Uworld: Toxoplasmosis encephalitis
Describe the diagnosis of Toxoplasma encephalitis:
- positive Toxoplasma Gondii IgG
- Multiple ring-enhancing brain lesions
Uworld: Toxoplasmosis encephalitis
Describe the treatment of Toxoplasma encephalitis:
- Sulfadiazine and pyrimethamine (Leucovorin)
- antiretroviral initiation
- prophylaxis: TMP-SMX (CD4 count < 100/ mm^3)
Infectious Disease: Hepatitis B
What is an essential step in the replication cycle in Hepatitis B virus?
Reverse transcription of template RNA to viral DNA
Infectious Diseases: Catheter related bloodstream infection
What are the most common pathogens causing nosocomial bloodstream infections?
- coagulase-negative streptococci
- staphylococcus aureus
- enterococci
- candida species
(commensal bacteria)
Infectious Diseases: Catheter related bloodstream infection
What is the usual cause of blood stream infections?
Intravascular catheters
Parasitology
Describe an infection caused by Clonorchis sinensis (Chinese liver fluke):
- endemic to Southeast Asia
- ingesting raw or undercooked freshwater fish
- causes biliary tract inflammation (cholangitis) that can turn recurrent
- pigmented (brown) gallstones
- increases the risk of cholangiocarcinoma
Parasitology
Describe an infection caused by Ascaris lumbricoides (roundworm):
- asymptomatic, may experience respiratory symptoms and GI distress causing Loeffler syndrome or bowel obstruction at the ileocecal valve.
- fecal oral transmission
- not commonly associated with cholangitis or pigment gallstone formation
Parasitology
Describe an infection caused by Dibothriocephalus lotus (former Diphyllobothrium latum) aka fish tapeworm:
- transmits by ingesting raw or undercooked freshwater fish
- asymptomatic, chronic infection can lead to vitamin b12 deficiency so a megaloblastic anemia can develop with neurological symptoms.
Parasitology
Describe an infection caused by Schistosome haematobium aka trematode:
- penetrates the skin and enters systemic circulation
- intermediate hosts are freshwater snails
- chronic infection inclue GU symptoms (hematuria, dysuria) and an increased risk of Squamous cell carcinoma of the bladder
- Sch. Mansoni and Sch. japonicum can lead to schistomiasis, which presents with diarrhea and abdominal pain
Parasitology
Describe an infection caused by Trichuris trichiura aka whipworm):
- fecal oral transmission of eggs
- diarrhea, iron deficiency anemia, growth delay, or rectal prolapse
Bootcamp: Mycology: Fungal Infectious Conditions- Dermatology
Pt with a round, pruritic, scaly lesion with central clearing is consistent with what?
How would you definitively diagnose?
- Dx: Tinea corporis aka “ringworm” caused by dermatophytes like Trichophyton, Epidermophyton, and Microsporum
- Definitive diagnose increased a KOH prep
Bootcamp: Systemic infections
Pt presents with flu-like symptoms, regional lymphadenopathy, and eyrthematous lesion, pain/inflammation and has pets.
What is causative agent?
Bartonella henselae
Bootcamp: Systemic infections
Pt presents with flu-like symptoms, regional lymphadenopathy, and eyrthematous lesion, pain/inflammation and has pets.
How would you diagnose for the causative agent?
- Polymerase chain reaction
- Bx using Warthin-Starry staining to visualize Bartonella henselae
Bootcamp: Systemic infections
Pt presents with flu-like symptoms, regional lymphadenopathy, and eyrthematous lesion, pain/inflammation and has pets.
How would you treat against the causative agent?
- Macrolides (azithromycin) for regional infection
- Macrolides (Erythromycin) or Tetracyclines (Doxycycline) for disseminated disease (Liver-peliosis hepatitis) or bacillary angiomatosis, or culture negative endcarditis
- If CNS or Endocarditis is involved, add rifampin to enhance penetrance
How do you prevent Rabies from progressing to get symptomatic?
Inactivated vaccine / Killed Vaccine
