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USMLE Step 1 > Microbiology > Flashcards

Microbiology Flashcards

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1
Q

Cytomegalovirus

A

Herpesvirus family

DS DNA
enveloped (takes from nuclear membrane)
icosahedral

Owl’s eye inclusion (basophilic intranuclear inclusion)

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2
Q

All DNA viruses are ___________ shaped except for _________

A

icosahedral

except pox viruses

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3
Q

Reovirus family

A

DS RNA
naked
icosahedral

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4
Q

Papillomavirus

A

DS DNA
naked
icosahedral

warts

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5
Q

Adenovirus

A

DS DNA
naked
icosahedral

pharyngoconjunctivitis
acute hemorrhagic cystitis
gastroenteritis

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6
Q

Parvovirus

A

SS DNA (only ss DNA virus)
naked
icosahedral

erythema infectiosum

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7
Q

paramyxovirus

A

SS - RNA
enveloped
helical

measles
mumps

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8
Q

flavivirus

A

SS + RNA
enveloped
icosahedral

hep C
yellow fever

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9
Q

Orthomyxovirus

A

SS - RNA
enveloped
helical

influenza

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10
Q

rhabdovirus

A

SS - RNA
enveloped
helical

rabies

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11
Q

togavirus

A

SS + RNA
enveloped
icosahedral

rubella

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12
Q

Hepatitis C family

A

flavivirus

SS + RNA
enveloped
icosahedral

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13
Q

Pseudomonas aeruginosa

A

Gram - ; Oxidase + ; aerobic non-fermenting bacillus

Produce blue-green pigment
Produce fruity odor

Tx fluroquinolones

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14
Q

Haemophilis

A

Gram - bacillus

Requires factors X and V

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15
Q

Gram + , Catalase - , Alpha hemolytic, optochin sensitive coccus

A

Streptococcus pneumoniae

bile soluble

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16
Q

Gram + , Catalase - , Beta hemolytic coccus

A 
Streptococcus agalactiae (bacitracin resistant)
Streptococcus pyogenes (bacitracin sensitive)
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17
Q

Staphylococcus aureus

A

Gram + ; Coagulase + ; Catalase + coccus

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18
Q

Catalase distinguishes these two species

A

Staphylococcus (+)

Streptococcus (-)

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19
Q

Coagulase distinguishes these staph species

A

Coagulase + –> Staph aureus

Coagulase - –> all others (epidermidis, saprophyticus)

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20
Q

Gamma-hemolytic, gram + cocci that grow on bile-esculin agar

A

Enterococci (Group D Strept)

Growth in NaCl: E.faecalis
No growth in NaCl: S. bovis

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21
Q

Alpha hemolytic, optochin resistant, gram + coccus

A

Streptococcus viridans

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22
Q

Alpha hemolytic, optochin sensitive, gram + coccus

A

Streptococcus pneumoniae

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23
Q

Herpes viruses are

A

DS DNA, enveloped, icosahedral

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24
Q

Branching, filamentous bacteria

A

Actinomyces
Nocardia

Both gram positive

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25
Lack a cell wall
Mycoplasma, Ureaplasma
26
Spirochetes
Borellia (Giemsa stain) Leptospira Treponema All gram negative
27
What subunits make up the bacterial ribosome?
50s and 30s | 40s and 60s in humans
28
What make spores resistant to dehydration?
Keratin-like coat, dipicolinic acid, peptidoglycan
29
Catalase positive organisms
``` Nocardia Pseudomonas Listeria Aspergillus Candida E.coli Staphylococci Serratia ```
30
Typical exotoxin diseases (think Gram +)
Tetanus, Botulism, diphtheria
31
Isolated in Bordet-Gengou agar
Bordetella pertussis
32
Virulence factors of staph aureus
Protein A: binds Fc of IgG, prevents opson/phago | TSST-1: cytokine release of IL-1, IL-2, IFN-y, TNF-a
33
IgA protease is used by these organisms and does this
S.pneumo, HiB, Neisseria (encapsulated) Cleaves IgA, colonizes respiratory mucosa
34
Which bugs do not gram stain well?
``` Treponema Mycobacteria Mycoplasma Legionella Rickettsia Chlamydia ```
35
Virulence factors of Enterotoxigenic E.coli
"ETEC" Heat-labile toxin (LT): + adenylate cyclase, + cAMP, +Cl secretion in gut (pushing out water) Heat-stable toxin (ST): + adenylate guanase, + gAMP, decrease NaCl resorption in gut (not resorbing water)
36
Isolated in Sabouraud agar
Fungi
37
These toxins may cause Hemolytic Uremic syndrome
``` Shiga toxin (ST) (causes dysentery) Shiga-like toxin (SLT) (EHEC O157) ```
38
Virulence factors of Group A Streptococci
(Strept pyogenes) M Protein: prevents phagocytosis Streptolysin O: degrades cell membrane Exotoxin A: cytokine release of IL-1, IL-2, IFN-y, TNF-a
39
Isolated in Thayer-Martin agar
Neisseria Contains vancomycin, trimetoprim, colistin and nystatin to inhibit all others
40
What is contained in Chocolate agar?
Factors V (NAD+) and X (hematin) Allows growth of Haemophilis influenzae
41
Isolated in Eaton agar (lipid-rich cell wall)
Mycoplasma pneumonia (requires cholesterol)
42
Mechanism of tetanospasmin toxin
SNARE inhibition of GABA/glycine --> spasticity, lockjaw
43
Mechanism of botulism toxin
SNARE inhibition of ACh --> flaccid, floppy
44
Virulence of Clostridium perfringens
Alpha toxin: phospholipase degrades tissue/cell membrane, causes myonecrosis and hemolysis
45
Second most common cause of UTI in young women
Staphylococcus saprophyticus
46
Diptheria toxin action on host cell
eEF-2 --> inhibits translocation during protein synthesis
47
Cholera toxin action on host cell
G-protein (Gs) --> increase cAMP in intestinal epithelium --> diarrhea
48
Pertussis toxin action on host cell
G-protein (Gi) --> increases cAMP causing edema, lymphocytosis, increased insulin secretion
49
Pseudomonas toxins action on host cell
Exotoxin A: eEF-2 --> inhibit translocation during protein synthesis Also Exotoxin S, function unknown
50
E. coli heat-labile toxin (LT) action on host cell
G-protein (Gs) --> increases cAMP in intestinal epithelium --> diarrhea
51
Botulism toxin action on host cell
Neurotoxin prevents neurosecretory vesicles from fusing with synaptic membranes and releasing acetylcholine
52
Shiga toxin action on host cell
Inhibit 60s ribosomal subunit --> decreasing protein synthesis
53
Tetanus toxin action on host cell
Neurotoxin that inhibits release of inhibitory neurotransmitters glycine and GABA
54
What are the positive sense RNA viruses?
``` Retrovirus Togavirus Flavivirus Coronavirus Hepevirus Calicivirus Picornavirus ```
55
What are the DNA viruses?
``` H - Hepadna H - Herpes A - Adeno P - Pox P - Parvo P - Papilloma P - Polyoma ```
56
What is the only ds RNA virus?
Reovirus
57
What are the killed vaccines?
R - rabies I - influenza P - Polio (salk) A - Hep A
58
What are the subunit vacines?
Hep B Virus | HPV
59
Where do DNA viruses replicate?
Nucleus | --> except poxvirus
60
Where to RNA viruses replicate?
Cytoplasm | --> except influenza and retrovirus
61
Virulence factors of Pseudomonas aeruginosa
Exotoxin A (protein synthesis inhibition) Elastase (degrades elastin, needed by blood vessels) Phospholipase C (degrades cell membranes) Pyocyanin (generates reactive oxygen species)
62
Lancet-shaped gram-positive organisms
Strep pneumo
63
Naked DNA Viruses
Adenovirus, Polyoma, Papilloma, Parvovirus
64
DNA Viruses (enveloped)
Poxvirus, Herpesvirus, Hepadna
65
RNA Viruses (enveloped)
Paramyxovirus, Rhabdovirus, Orthomyxovirus, Coronavirus, Flavivirus, Togavirus
66
Naked RNA Viruses
Reovirus, Calcivirus, Hepevirus, Picornavirus
67
Congenital infection resulting in diffuse intracranial calcifications, hydrocephalus, chorioretinitis, CSF pleocytosis or elevated CSF protein
Toxoplasmosis
68
Congenital infection resulting in skeletal abnormalities, pseudoparalysis, rhinitis, macropapular rash
Syphilis
69
Congenital infection resulting in heart disease, sensorineural hearing loss, cataracts, glaucoma
Rubella
70
Congenital infection resulting in hepatosplenomegaly, sensorineural hearing loss, thrombocytopenia, periventricular intracranial calcifications, microcephaly
CMV
71
Congenital infection resulting in Conjunctivitis, thrombocytopenia, elevated liver enzymes, mucocutaneous vesicles/scarring
Herpes simplex virus
72
Hep A family, transmission, disease character
Picornavirus (RNA), fecal-oral, mild acute disease (IgM-HAV)
73
Hep B family, transmission, disease character
Hepadnavirus (DNA), sex/parenteral, acute/occassional chronic, HBsAg/IgM-HBcAg
74
Hep C family, transmission, disease character
Flavivirus (RNA), parenteral/IVDU/sex, acute --> chronic, Ab to HCV
75
Hep D family, transmission, disease character
Delta (circular RNA), parenteral/sex, coinfection HBV, Ab to HDV + HBsAg
76
Hep E family, transmission, disease character
Hepevirus (RNA), Fecal-oral, mild unless pregnant, Ab to HEV
77
Virulence factors of Strep pneumo
Polysaccaride capsule, prevents phagocytosis, more than 90 types of capsule antigens Also: IgA protease, adhesins, pneumolysin
78
Characteristics of Histoplasma capsulatum
Ovoid cells within macrophages Dimorphic fungus found in soil, bird, bat droppings Mississippi and Ohio River basins Forms granulomata, causes lymphadenopathy, hepatosplenomegaly, acute pulmonary disease
79
Characteristics of Coccidioides immitis
Spherules packed with endospores Pulmonary disease in immunocompetent Southwest US
80
Characteristics of Cryptococcus neoformans
Budding yeast with thick capsule found in soil with bird/pigeon droppings Meningoencephalitis and pulmonary disease in immuocompromised
81
Characteristics of candida
Yeasts that form pseudohyphae
82
Characteristics of Aspergillus
Septate hyphae with V-shaped branching | Pulmonary disease in immunocompromised

USMLE Step 1 (5 decks)

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