High Yield Topics-Microbiology Flashcards
What STI presents with a painless genital ulcer followed several weeks later by a diffuse maculopapular rash involving the palms and soles
syphilis (Treponema pallidum)
- spirochete
First-line treatment for syphilis
penicillin
MOA of penicillin
binds to bacterial transpeptidase and interferes with bacterial cell wall synthesis through the inhibition of peptidoglycan cross-linking
spread by respiratory droplets and present with an erythematous rash, “arthralgias”, “postauricular lymphadenopathy”, and fever
Rubella infection
An infection during pregnancy –> infant manifests with cataracts, sensorineural deafness, and congenital heart disease (patent ductus arteriosus), and microcephaly
congenital rubella infection
Rubella infection can be prevented by
measles-mumps-rubella (MMR) vaccination
what kind is MMR vaccination?
live-attenuated vaccine
- contraindicated during pregnancy!
Presents with a fever, cough, “conjunctivitis”, and a maculopapular rash; no postauricular lymphadenopathy or arthralgias
Measles virus
An infection during pregnancy –> infant presents with increases the risk for fetal demise and low birth weight
congenital measles
An infection during pregnancy –> infant presents with localized lesions of the skin, eyes, and mouth + encephalitis and multiorgan dysfunction
Herpes simplex virus (HSV)
An infection during pregnancy –> infant presents with intrauterine growth restriction, hepatosplenomegaly, petechiae, jaundice, thrombocytopenia, microcephaly, and chorioretinitis
Cytomegalovirus
Neurocysticercosis (calcified nodules and some cysts of brain) is caused by
pork tapeworm (aka.Taenia solium)
Source of pork tapeworm Taenia solium
raw or undercooked, infected pork
Azoles (-conazole) inhibits the production of ergosterol (part of the fungal cell membrane) by
inhibiting the cytochrome P450-dependent demethylation reaction that synthesizes ergosterol from lanosterol.
Prevention of cross-linking of β-glucans in the cell wall is the mechanism of action of
echinocandins
Pore formation in the fungal cell membrane is the mechanism of action of
amphotericin B and nystatin
Inhibition of DNA and RNA synthesis is the mechanism of action of what fungal tx?
flucytosine
- tx for cryptococcal meningitis
Prevention of tetrahydrofolic acid synthesis is the mechanism of action of
Sulfonamides and trimethoprim
antibody that indicates immunity to hepatitis B due to vaccination or recovery from infection.
Anti-HBs
Mnemonic for Viral hepatitis B markers
SpECiES
S: HBsAg
E: HBeAg
C: HBcAg
E: Anti-HBe
S: Anti-HBs
antibody that indicates low transmissibility of hepatitis B
Anti-HBe
the sole ⊕ marker of viral hepatitis B infection during window period
Anti-HBc (IgM)
Three genes encoded by HIV RNA (diploid genome = two ssRNAs)
- env
- gag
- pol
What structural proteins are encoded by env gene?
glycoprotein 160 (later cleaves into gp120 and gp41)
Function of gp 120
attachment to host CD4+ T cell
Function of gp 41
fusion and entry
What structural proteins are encoded by gag gene?
p24 and p17
Function of p24
capsid protein
Function of p17
matrix protein
What structural proteins are encoded by pol gene?
Reverse transcriptase
Integrase
Protease
*STUDY AID: RIP Pol
Function of Reverse transcriptase
synthesizes dsDNA from viral RNA
Function of Integrase
integrates dsDNA into host genome
Function of Protease
Cleaves protein formed from dsDNA
HIV binds to what co-receptor on CD4 T cells?
CXCR4
HIV binds to what co-receptor on macrophages?
CCR5
What does HIV acquire through budding from host cell plasma membrane?
envelope glycoproteins and envelope
HIV is diagnosed using
- know this cold!
HIV-1/2 Ag/Ab testing
- It detects viral p24 “antigen” capsid protein + IgG “antibodies” to HIV 1 and HIV 2
HIV-1/2 Ag/Ab immunoassays has _____ sensitivity/specificity
high
What test is used to confirm HIV in case of indeterminate HIV-1/2 Ag/Ab immunoassays?
Nucleic acid test (NAT)
- aka. viral load test (measure the amount of the genetic material (RNA) of HIV in the blood)
High viral load is used to monitor effect of
drug therapy
HIV genotyping is used to determine
appropriate therapy
AIDS can be diagnosed by what two criteria?
- low CD4+ T cell count
OR
- HIV ⊕ with AIDS-defining condition (Pneumocystis pneumonia)
What CD4+ T cell count is used to diagnose AIDS?
≤ 200 CD4+ cells/mm3
Since HIV-1/2 Ag/Ab testing is not recommended in babies with suspected HIV due to maternally transferred antibody, what is used instead?
HIV viral load
What are the four stages of untreated infection?
- HINT: 4 F’s
- Flu-like (acute)
- Feeling fine (latent)
- Falling count
- Final Crisis
Amount of HIV RNA (viral load) is inversely proportional to
CD4+ T cell count
Describe amount of HIV RNA and CD4+ T cell count during four stages of untreated infection
- Flu-like (acute)
- high HIV RNA
- CD4+ T cell count drops - Feeling fine (latent)
- relatively low HIV RNA
- CD4+ T cell count increases - Falling count
- progressive increase of HIV RNA
- progressive decrease of CD4+ T cell count - Final Crisis
- high HIV RNA
- very low CD4+ T cell count (<200) –> death
HIV RNA is relatively low during latency phase b/c
Virus replicates in lymph nodes during latency phase
What pathogen is responsible for oral hairy leukoplakia on tongue in HIV patients?
EBV
How to distinguish oral thrush (by candida) vs. oral hairy leukoplakia (by EBV)
oral thrush is scrapable vs. oral hairy leukoplakia is unscrapable
A condition that presents with loss of memory, difficulty thinking, concentrating, speaking clearly, etc. due to HIV virus spreading to the brain
HIV dementia
Imaging findings of HIV dementia
cerebral atrophy on neuroimaging
What pathogen is responsible for progressive multifocal leukoencephalopathy (brain white matter disease) and areas demyelination on MRI in HIV patients?
John Cunningham virus
aka. JC virus
What pathogen is responsible for pneumonia in HIV patients with CD4+ cell count <200?
Pneumocystis jirovecii
Chest imaging finding of Pneumocystis jirovecii pneumonia
“Ground-glass” opacities
What pathogen is responsible for pleuritic pain and hemoptysis?
Aspergillus
Chest imaging finding of Aspergillus fumigatus
Cavitation or infiltrates
What pathogen is responsible for bacillary (rod-shaped) angiomatosis in HIV patients?
Bartonella spp
Biopsy findings of bacillary (rod-shaped) angiomatosis
neutrophilic inflammation
What pathogen is responsible for esophagitis in HIV patients?
Candida albicans
What endoscopy finding is associated with esophagitis caused by Candida albicans?
White plaques on endoscopy
What biopsy finding is associated with esophagitis caused by Candida albicans?
yeast and PSEUDOHYPHAE on biopsy
What pathogen is responsible for Colitis, Retinitis, Esophagitis, Encephalitis, and Pneumonitis in HIV patients?
CMV
- STUDY AID: CMV causes CREEP
What pathogen is responsible for linear ulcers on endoscopy?
CMV
What pathogen is responsible for cotton-wool spots on fundoscopy?
CMV
What biopsy finding is associated with CMV infections?
- HINT: same as in all CMV infections
cells with intranuclear inclusion bodies (owl eyes)
What pathogen is responsible for meningitis in HIV patients?
Cryptococcus neoformans
What pathogen is responsible for encapsulated yeast on india ink stain or capsular antigen +?
Cryptococcus neoformans
- STUDY AID: sketchyMicro
What pathogen is responsible for chronic, watery diarrhea in HIV patients?
Cryptosporidium spp
What pathogen is responsible for Acid-Fast oocysts in stool
Cryptosporidium spp
What pathogen is responsible for B-cell lymphoma (diffuse large b cell lymphoma, non-Hodgkin lymphoma, and CNS lymphoma) in HIV patients?
EBV
What pathogen is responsible for nonspecific symptoms such as fever, night sweats, weight loss or focal lymphadenitis in HIV patients?
Mycobacterium avium
What pathogen is responsible for brain abscesses in HIV patients?
Toxoplasma gondii
How to distinguish CNS lymphoma (EBV) vs. Toxoplasma gondii on brain MRI
Toxoplasma gondii: MULTIPLE ring-enhancing lesions
CNS Lymphoma by EBV: SOLITARY ring-enhancing lesion
Faulty nucleo”sides” that halt reverse transcriptase’s activity of converting ssRNA to dsDNA –> early chain termination
NRTIs
- Lamivudine
- Zidovudine
- Stavudine
- Didanosine
- Emtricitabine
- Abacavir
- STUDY AID: “Dine” with my “nuclear (nucleosides)” family
NRTIs are missing what on its nucleoside?
3’OH
NRTIs must be _____ to be activated b/c they are nucleosides
phosphorylated
The only NRTI that is a nucleo”tide”
“T”enofovir
Tenofovir must be phosphorylated a total of ___ times to be active
3
already phosphorylated but must be phosphorylated two times more to be active
Which NRTI has an adverse effect of myelosuppression (bone marrow suppression), leading to anemia and neutropenia (agranulocytosis)?
Zidovudine
Tx to reverse bone marrow suppression caused by Zidovudine?
- G-CSF (granulocyte colony-stimulating factor)
- Erythropoietin
Allele that increased the risk of Type 4 hypersensitivity with Abacavir
HLA-B 57:01
- STUDY AID:
- Book: HLA-B
- Page: 57
- Line: 1