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Microbiology Flashcards

1
Q

Function of Peptidoglycan on bacteria

A

Protects against osmotic pressure

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2
Q

Function of Periplasm

A

On G(-) bacteria Contain hydrolytic enzymes (B-lactamase)

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3
Q

Function of Capsule

A

Protects phagocytosis

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4
Q

Function of pilus/fimbria

A

Adherence of bacteria to cell surface/conjugation (made of glycoprotein)

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5
Q

Composition of spore

A

Keratin-like coat; dipicolinic acid; peptidoglycan

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6
Q

Function of plasmid

A

Antibacterial resistance, enzymes, toxins

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7
Q

Function of glycocalyx

A

Mediates adherence to surface (catheters) Teicholic acid in G(+)

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8
Q

Gram stain limitations (organisms)

A

“These rascals may microscopically lack color” Treponema (dark field microscopy or fluorescent) Rickettsia (intracellular) Mycobacteria (high lipid) Mycoplasma (no cell wall) Legionella (silver stain - intracellular) Chlamydia (intracellular)

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9
Q

PAS stain

A

Stains glycogen (Dx: Whipple’s dz - tropheryma whipplei)

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10
Q

India Ink

A

Cryptococcus neoformans (stains background)

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11
Q

Silver stain

A

Fungi (pneumocystis), legionella, H. Pylori

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12
Q

Ziehl-Neelsen (carbol fuchsin)

A

AKA Acid-fast stain (mycobacteria, norcardia)

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13
Q

H. influenzae culture requirement

A

Chocolate agar (Factor V - NAD+ and X - hematin)

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14
Q

Nisseria culture requirement

A

Thayer Martin (VPN) Vanco (inhibit G+) Polymyxin (inhibit G-) Nystatin (inhibit fungus)

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15
Q

B. Pertussis culture requirement

A

Bordet Gengou

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16
Q

M. tuberculosis culture requirement

A

Lowenstein-Jensen agar

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17
Q

MacConkey agar components

A

Bile salt+ Crystal violet: Inhibit G(+) growth Lactose/neutral red - stains lactose fermenters pink

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18
Q

Obligate aerobes organisms

A

“Nagging Pests Must Breathe” Nocardia Psuedomonas Mycobacteria Bacillus

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19
Q

Obligate anaerobes organisms

A

“Can’t Breathe Air” Clostridium Bacteroides Actinomyces (faculative)

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20
Q

Obligate intracellular organisms

A

“really cold” Rickettsia Chlamydia

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21
Q

Faculative intracellular organisms

A

“Some Nasty Bugs May Live FaculativeLY”

Salmonella Nisseria Brucella Mycobacterium Listeria Francisella Legionella Yersinia

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22
Q

Encapsulated organisms - What test is used to determine if organism has capsule or not? - Capsular vaccines?

A

SHiNE SKiS Strep Pneumonae ** H. Influenzae ** Nisseria ** E. Coli Strep Group B Klebsiella Salmonella - Detected by Quelling reaction ** = vaccines

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23
Q

IgA Protease producing organisms

A

SHiN Strep Penmonae H. Influenze Nisseria

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24
Q

Bacteria conjugation

A

F+ x F-: transfer plasmid Hfr x F-: transfer chromosomal DNA

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25
Bacterial transformation
Picks up free DNA
26
Bacterial Transposition
DNA jumps from one location to another (can be from plasmid to/from chromosome)
27
Bacterial transduction
Generalized: Lytic phage Specialized: Lysogenic phage
28
Protein A producing organisms
S. Aureus (binds Fc of IgA - prevents phagocytosis)
29
Diptheria toxin
Ribosylation from NAD to histamine - inactivate EF2 Parhyngitis with psuedomembranes + lymphadeopathy (bull neck) - do not scrape -\> dissemination of toxin
30
psueodmonas exotoxin
Exotoxin A - Ribosylation of EF2
31
Shiga toxin
From shigella (invade host cells) or EHEC (O157:H7 - do not invade host) Inactivate 60S by removing adenine from rRNA - enhances cytokine release causing HUS
32
ETEC toxins
LT (heat liable) - Activates adenyl cyclase (increase H2O and Cl- secretion) ST (heat stable) - activate guanylate cyclase (decrease NaCl absorption)
33
Bacillus anthracis toxin
Mimics adenyl cyclase - increase cAMP - characteristic black eschar in cutaneous anthrax
34
Vibrio cholerae toxin
Overactivate adenyl cyclase by activating Gs - H2O and Cl- secretion Rice water diarrhea
35
Pertussus toxin
Disable Gi - overactivate adenyl cyclase Cough on expiration and whoops on inspiration
36
Clostridium tetani toxin
Cleave SNARE protein -\> Inhibit inhibitor neurotransmitter (GABA/glycine) in spinal cord
37
Clostridum Botulism toxin
Cleave SNARE protein -\> Prevents release of stimulatory signal (ACh)
38
Clostridium perfringens toxin
Phospholipase that degrades tissue/cell membranes (degrade phospholipase C - myonecrosis and hemolysis)
39
Streptococcus pyogenes exotoxin
Streptolysin O - degrade cell membrane (lyse RBC) Exotoxin A - Bring MHC II and TCR together -\> IFN-g and IL-2 release (shock)
40
Staph aureus toxin
TSST-1 - Bring MHCII and TCR together -\> release IFN-g and IL-2 (shock)
41
Nisseria Gonococci characteristics
No polysaccharide capsule No maltose fermentation (ferments glucose) No vaccine (rapid antigenic vairation of pilus) Sexually transmitted Causes gonorrhea, septic arthritis, neonatal conjuncitivits, PID, Fitz-Hugh-Curtis syndrome (infected liver capsule)
42
Nisseria Meningococci characteristics
Capsule Maltose fermentation Vaccine Respiratory and oral secretions Causes meningococcemia and meningitis, Waterhouse fredricksen syndrome Rifampin prophylaxis in close contacts
43
Haemophoilus influenzae characteristics
Causes epiglottitis, meningitis, ottis media, pneumonia (haEMOPhilus) Produces IgA protease Culture on chocolate agar (X and V) Treat meningitis with ceftriaxone. Rifampin prophyalxis on close contacts
44
Legionella pneumophilia characteristics
Causes atypical pnemonia and fever. Pontiac fever Silver stains Culture on charcoal yeast extract - iron and cysteine Water source spread. Tx: Erythromycin
45
Psuedomonas aeruginosa characteristics
Pneumonia, sepsis (black lesions on skin), External otitis (swimmer's ear), UTI, drug use, Diabetic osteomyelitis, hot tub folliculitis (PSUEDOmonas) Aerobic G(-) rod, non-lactose fermenting, oxidase positive pyocyanin (blue-green) pigment; grape-like odor Endotoxin (fever/shock) and exotoxin A (inactivate EF2) Tx: Aminoglycoside + pipercilin/ticarcillin
46
E. Coli characteristics
EIEC: Shiga-like toxin. Invade intestinal mucosa and toxin causes necrosis/inflammation (fever/diarrhea) ETEC: Labile/stable toxin (no invasion) EPEC: Pediatics - Adheres to apical surface, flattens villi and prevents absorption EHEC: O157:H7. Shiga-like toxin - HUS. Does not ferment sorbitol
47
Klebsiella characteristics
Lobar pneumonia by aspiration (alcoholics/DM) and nocosomial UTI Red currant jelly sputum 4A's: Aspiration, abscess in lungs, alcoholis, di-A-betes
48
Hepatitis A Type of virus, transmission and duration
RNA picronavirus (SS+ linear) Fecal-oral route **A**cute, **A**symptomatic (usually), **A**lone (no carriers
49
Hepatitis B ## Footnote Type of virus, transmission, duration, and mechanism
DNA hepadenavirus (dS-DNA, linear) Transmission: Sexual, maternal-fetal Usually acute, can be chronic. Can cause hepatocellular carcinoma (check AFP) Cellular RNA polymerase transcribes RNA from DNA template. Reverse transcriptase transcribes DNA genome from RNA intermediate. Viron enzyme: DNA-dependent DNA polymerase
50
Hepatitis C ## Footnote Type of virus, transmission, duration, and mechanism
RNA flavivirus (SS-linear) Transmission: Blood transfusion, IV drug users Chronic, cirrhosis, carcinoma (check AFP), carriers Tx: IFN-a, ribaviron
51
Hepatitis D ## Footnote Type of virus, transmission, duration, and mechanism
Delta agent Requres HbSAg. causes coinfection - fullminant hepatitis
52
Hepatitis E ## Footnote Type of virus, transmission, duration, and mechanism
RNA hepevirus (SS + linear) Tranmission: **E**nterically (water-borne **e**pidemics) High mortality in pregnant women
53
What is the **p24 protein** on HIV virus?
Capsid protein
54
What is the gp41 protein on HIV virus?
Allows fusion and entry
55
What is the gp120 protein on HIV virus?
Attaches to host T-cells
56
What receptor does HIV bind on T-cells?
X4 HIV virus binds CXCR4 and CD4 on CD4 T-cells
57
What receptor does HIV bind on macrophages?
R5 HIV virus binds CCR5 and CD4 on macrophages
58
IFN-a used for?
Chronic hepatitis B and C, kaposi sarcoma
59
IFN-B used for?
MS
60
IFN-g used for?
NADPH oxidase deficiency

USMLE (8 decks)

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