Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

USMLE Step 1: Things I Cannot Remember > Microbiology > Flashcards

Microbiology Flashcards

1
Q

What bacteria produce enzymes that inhibit protein synthesis?

A
  1. Corynebacterium diptheriae
  2. Pseudomonas aeruginosa
  3. Shigella
  4. EHEC
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How are C. diptheriae and P. aeruginosa similar?

A

produce toxins that inactivate EF-2

  1. C. diptheriae ⇒ diptheriae toxin
  2. P. aeruginosa ⇒ exotoxin A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How are shigella and EHEC similar?

A

produce toxin that inactivate 60S ribosome by removing adenosine from rRNA

  1. Shigella ⇒ shiga toxin
  2. EHEC ⇒ shiga-like toxin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What bacteria produce toxins that increase fluid secretion?

A
  1. ETEC ⇒ heat-labile (similar to cholera toxin) & heat-stabile toxins
  2. Bacillus anthracis ⇒ edema toxin
  3. Vibrio cholerae ⇒ cholera toxin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What bacteria produce toxins that inhibit phagocytic ability?

A

Bordetella pertussis ⇒ pertusis toxin

  • overactivates adenylate cyclase (↑ cAMP) by disabling Gi subunit ⇒ impairs phagocytosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What bacterial toxins act by inhibiting neurotransmitter release?

A
  1. Clostridium tetani ⇒ tetanus toxin
  2. Clostridium botilinum ⇒ botulinum toxin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What bacteria produce toxins that lyse cell membranes?

A
  1. Clostriudium perfringens ⇒ α-toxin
  2. Streptococcus pyogenes ⇒ Streptolysin O
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What bacteria produce superantigens that cause shock?

A
  1. Staphylococcus aureus ⇒ toxic shock syndrome toxin (TSST-1)
  2. Streptococcus pyogenes ⇒ Exotoxin A
  • Binds to MHC-II and TCR outside of antigen binding site to cause overwhelming release of IL-1, IL-2, IFN-γ and TNF-α ⇒ shock
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Where is the endotoxin found in bacterial species?

A

LPS found in most outer membrane of G(-) bacteria (both cocci and rods)

  • Edema
  • Nitric oxide
  • DIC/Death
  • Outer membrane
  • TNF-α
  • O-antigen
  • Xtremely heat-stabile
  • IL-1
  • Neutrophil chemotaxis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is falsely positive in babies born to HIV(+) mothers?

A

ELISA and Western blot tests

  • falsely positives in neonates born to HIV infected mothers
    • anti-gp120 Abs cross the placenta
  • Need PCR to confirm
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the extended spectrum of amoxicillin/ampicilllin?

A

G(+) & HHELPSS

  1. H. influenzae
  2. H. pylori
  3. E. coli
  4. Listeria
  5. Proteus mirabilis
  6. Salmonella
  7. Shigella
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Which pencillin-like antibiotic is used for S. Areus?

A

Nafcillin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Which pencillin-like antibiotics are used for P. aeruginosa and G(-) rods?

A

Piperacillin & ticarcillin (used w/ β-lactamase inhibitors)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What do 1st generation cephalosporins treat?

A

PEcK

  1. Proteus mirabilis
  2. E. coli
  3. Klebsiella pneumoniae
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What do 2nd generation cephalosporins treat?

A

HEN PEcKS

  • Haemophilus influenzae
  • Eneterobacter
  • Neisseria spp.
  • Proteus mirabilis
  • E. coli
  • Klebsiella
  • Serratia
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What do 3rd generation cephalosporins treat?

A

Serious G (-) infections

  1. Ceftriaxone ⇒ meningitis, gonorrhea, disseminated Lyme’s disease
  2. Ceftazidime ⇒ Pseudomonas
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What 4th generation cephalosporins treat?

A

Broad G (+) and G (-) coverage:

  • ↑ activity against P. aerigunosa
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What do 5th generation cephalosporins treat?

A

Broad G (+) and G (-) coverage, including MRSA:

  • does not cover P. aerigunosa
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What do monobactams cover?

A

G (-) rods only

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

List the protease inhibitors:

A

drugs ending in -navir

  • Atazanavir
  • Darunavir
  • Fosamprenavir
  • Indinavir
  • Lopinavir
  • Ritonavir
  • Saquinavir
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the side effects of protease inhibitors?

A
  • Hyperglycemia
  • GI intolerance
  • Lipodystrophy
  • Nephropathy, hematuria (indinavir)
  • Rifampin (CYP/UGT inducer) is contraindicated
    • ↓ protease inhibitor concentration
22
Q

List the NRTIs:

A
  • Abacavir
  • Didanosine
  • Emtricitabine
  • Lamivudine
  • Stavudine
  • Tenofovir
  • Zidovudine
23
Q

What are the side effects of NRTIs?

A
  • Bone marrow suppression
    • reversed w/ G-CSF and erythropoietin
  • Peipheral neuropathy
  • Lactic acidosis
  • Anemia (ZDV)
  • Pancreatitis (didanosine)
24
Q

List the NNRTIs:

A
  1. Delaviridine
  2. Efavirenz
  3. Nevirapine
25
What are the side effects of NNRTIs?
* **Rash** * **Hepatotoxicity** * Vivid dreams and CNS symptoms (efavirenz) **Note:** * Delaviridine & efavirenz are contraindicated in pregnancy
26
List the **integrase inhibitors:**
**Raltegravir**
27
What are the side effects of integrase inhibtors?
**↑ creatine kinase**
28
List the **fusion inhibitors:**
1. Enfuvirtide 2. Maraviroc
29
What are the side effects of fusion inhibitors?
1. **Enfuvirtide ⇒** skin reaction (injection site) 2. **Maraviroc ⇒** hepatic & CV problems
30
When are interferons used?
1. **IFN-α** * chronic Hep B & C, Kaposi sarcoma, hairy cell leukemia, condyloma acuminatum. renal cell carinoma, malignant melanoma 2. **IFN-β** * multiple sclerosis 3. **IFN-γ** * chronic granulomatous disease (CGD)
31
What are the side effects of IFNs?
1. Neutropenia 2. Myopathy
32
What can be used for **Hep C therapy**?
1. **Ribavirin** (also used in RSV) * Inhibits synthesis of guanine nucleotides by competitively inhibiting IMP dehydrogenase * Toxicity ⇒ hemolytic anemia, severe teratogen 2. **Simeprevir** * HCV protease inhibitor ⇒ prevents viral replication * Toxicity ⇒ Photosensitivity, rash 3. **Sofosbuvir** * Inhibits HCV RNA-dependent RNA polymerase ⇒ chain terminator * Toxicity ⇒ fatigue, headache, nausea
33
**Pneumonia:** Special Groups * **Alcohol/IV drug abusers** * **Aspiration** * **Atypical** * Cystic fibrosis * **Immunocomrpomised** * Nocosomial (hospital acquired) * Postviral
* **Alcohol/IV drug abusers** * S. Pneumonae, Klebsiella, S. Areus * **Aspiration** * Anaerobes (Peptostreptococcus, Fusobacterium, Prevotella, Bacteriodes) * **Atypical** * Mycoplasma, Legionella, Chlamydia * _Cystic fibrosis_ * _Pseudomonas_, S. Areus, S. Pneumonae * **Immunocomrpomised** * S. Areus, enteric gram (-) rods, fungi, viruses, P. *Jirovecii* (w/ HIV) * Nocosomial (hospital acquired) * S. Areus, Pseudomonas, other enteric gram (-) rods * Postviral * S. Areus, H. Influenzae, S. Pneumonae
34
1. What infections cause a brain abscess? 2. Does site of infection predict where an abscess will form?
1. **Infections:** * Most commonly **viridans strep and S. Areus** * **Toxoplasma** ⇒ reactivation in AIDS * If dental infection/extraction precedes ⇒ oral anaerobes 2. **Site of abscess:** * Multiple abscesses ⇒ bacteremia * Single lesion ⇒ contigious sites * otitis media and mastoiditis ⇒ temporal lobe and cerebellum * sinusititis and dental infection ⇒ frontal lobe
35
What viruses cause meningitis?
* Enteroviruses (esp. Cocksackie virus) * HSV 1 (encephalitis) * HSV 2 * HIV (also consider Cryptococcus spp.) * West Nile virus (also can cause encephalitis) * VZV
36
**CSF findings in meningitis:** 1. Bacterial 2. Fungal 3. Viral
1. **Bacterial** * Opening pressure: ↑ * Cell type: ↑ PMNs * Protein: ↑ * Sugar: ↓ 2. **Fungal** * Opening pressure: ↑ * Cell type: ↑ lymphocytes * Protein: ↑ * Sugar: ↓ 3. **Viral** * Opening pressure: normal/↑ * Cell type: ↑ lymphocytes * Protein: normal/↑ * Sugar: normal
37
1. What are the **ToRCHeS** infections? 2. What are the common clinical findings of these infections?
1. **Infections:** * **T**oxoplasma gondii * **O**ther: S. Agalactiae, E. Coli, Listeria, Parvovirus B19 (hydrops fetalis) * **R**ubella * **H**IV and **H**SV-2 * **S**yphillis 2. **Common clinical findings:** * heptasplenomegaly, jaundice, growth retardation, thrombocytopenia
38
Describe ***Toxoplamsa gondii*** infection in **neonates:** * **Mode of transmission** * **Maternal Manifestations** * **Neonatal manifestations**
* **Mode of transmission** * cat feces or ingestion of undercooked meat * **Maternal Manifestations** * Usually _asymptomatic_; lymphadenopathy (rarely) * **Neonatal manifestations** * **​Classic triad** (**chic**)**:** _**c**horiorentinits_, _**h**ydrocephalus_, _**i**ntracranial **c**alcifications_ * +/- "blueberry muffin" rash
39
Describe **Rubella** infection in **neonates:** * **Mode of transmission** * **Maternal Manifestations** * **Neonatal manifestations**
* **Mode of transmission** * Respiratory droplets * **Maternal Manifestations** * Rash, lymphadenopathy, _arthritis_ * **Neonatal manifestations** * **Classic triad****:** _PDA_ (pulmonary artery hypoplasia), _cataracts_, _deafness_ * +/- "blueberry muffin" rash
40
Describe **CMV** infection in **neonates:** * **Mode of transmission** * **Maternal Manifestations** * **Neonatal manifestations**
* **Mode of transmission** * sexual contact, organ transplant * **Maternal manifestations** * usually asymptomatic; _mononucleosis-type illness_ * **Neonatal manifestations** * **seizures** * **petechial rash** * **periventricular calcifications** * hearing loss * "blueberry muffin" rash
41
Describe **HIV** infection in **neonates:** * **Mode of transmission** * **Maternal manifestations** * **Neonatal manifestations**
* **Mode of transmission** * sexual contact, needlestick * **Maternal manifestations** * variable depending on CD4 count * **Neonatal manifestations** * _recurrent infections_ * _chronic diarrhea_
42
Describe **HSV-2** infection in **neonates:** * **Mode of transmission** * **Maternal manifestations** * **Neonatal manifestations**
* **Mode of transmission** * skin or mucous membrane contact * **Maternal manifestations** * usually asymptomatic; herpetic (vesicular) lesions * **Neonatal manifestations** * **encephalitis** * herpetic (vesicular) lesions
43
Describe **Syphillis** infection in **neonates:** * **Mode of transmission** * **Maternal manifestations** * **Neonatal manifestations**
* **Mode of transmission** * sexual contact * **Maternal manifestations** * Chancre (1°) and disseminated rash (2°) - stages most likely to result in fetal infection * **Neonatal manifestations** * often results in **stillbirth, hydrops fetalis** * If child survives: * facial abnormalities (notched teeth, saddle nose, short maxilla) * saber shins * CN 8 deafness
44
Bacteria with a **branching filamentous** appearance:
* **Actinomyces** (G+) * **Nocardia** (weakly acid-fast)
45
Bacteria with a **pleomorphic** appearance:
* **Chlamydiae** (Giesma) * **Ricketssiae** (Giesma) These are both G- bacteria but cannot be viewed on gram stain
46
**Spiral** bacteria:
Spirocetes (G-): * **Borrelia** (Giesma) * **Leptospira** * **Treponema**
47
Bacteria with **no cell wall:**
* Mycoplasma * Ureaplasma (contains sterols)
48
Bacteria that cannot be viewed on Gram stain:
**T**hese **M**icrobes **M**ay **L**ack **R**eal **C**olor * **T**reponema * **M**ycobacteria * **M**ycoplasma * **L**egionella * **R**icketssia * **C**hlamydia
49
**Stains:** * Giesma * PAS (periodic acid-Schiff) * Ziehl Neelsen * India ink * Silver stain
* Giesma: * **Chlamydia, Borrelia, Ricketssia, Trypanosomes, Plasmodium** * PAS (periodic acid-Schiff): stain **glycogen,** mucopolysaccharides * Diagnoses Whipple disease (*Tropheryma whipplei*) * Ziehl Neelsen (carbol fuschin): * acid fast bacteria (**Norcardia, Mycobacteria**) * protozoa (**Cryptosporidium oocysts**) * India ink: * **Cryptococcus neoformans** * Silver stain: * **Fungi** (e.g. Pneumocystis) * **Legionella** * ***H. Pylori***
50
Special Culture Requirements: 1. H. Influenzae ⇒ 2. Neisseria ⇒ 3. Bordetella pertussis ⇒ 4. C. Diphtheriae ⇒ 5. M. tuberculosis ⇒ 6. M. pneumonia ⇒ 7. Lactose-fermenting enterics ⇒ 8. E. coli ⇒ 9. Legionella ⇒ 10. Fungi ⇒
1. H. Influenzae ⇒ **Chocolate agar** * **​​**Factors **V (NAD+)** and **X (hematin)** 2. Neisseria ⇒ **Thayer-Martin agar** * **​​Vancomycin, Trimethoprin, Colistin, Nystatin** 3. **Bordet**ella pertussis ⇒ **Bordet**-Gengou agar, Regan-Lowe medium 4. C. Diphtheriae ⇒ **Tellurite** agar, **Löffler** medium 5. M. tuberculosis ⇒ **Löwenstein-Jensen** agar 6. M. pneumonia ⇒ **Eaton** agar (requires _cholesterol_) 7. Lactose-fermenting enterics ⇒ **MacConkey** agar * _fermentation produces acid_, causing colonies to turn **pink** 8. E. coli ⇒ Eosin-methylene blue * colonies w/ **metallic green sheen** 9. Legionella ⇒ **silver stain** * **Charcoal yeast extract** _agar buffered with cysteine and iron_ 10. Fungi ⇒ **Sab**ouraud agar
51

USMLE Step 1: Things I Cannot Remember (16 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions