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NPLEX I 2024 > Microbiology > Flashcards

Microbiology Flashcards

1
Q

appendages of bacteria and their purpose

A

flagellum
- protein
- motility

pilus/fimbria
- glycoprotein
- helps bacteria adhere to cell surface
- forms “sex pilus” during conjugation (transfer of DNA from one bacteria to another)

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2
Q

components of bacterial cell envelopes

A

capsule (not all bacteria)
- polysaccharide
- protects against phagocytosis

slime (S) layer
- polysaccharides (loose network)
- helps with cell adhesion
- supports biofilm formation
- common in indwelling catheters

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3
Q

why can encapsulated bacteria cause more severe disease?

A

the capsule prevents macrophages from identifying the bacteria before opsonization with Ab, can hangout in the body and cause damage longer before they are identified

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4
Q

what are the important encapsulated bacteria?

A

Please SHine my SKis
- pseudomonas aeruginosa
- strep pnemoniae (not opsonized)
- H flu type B (not opsonized)
- neisseria meningitidis (not opsonized)
- e coli
- salmonella
- klebsiella pneumoniae
- group B strep

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5
Q

components of outer membrane of gram negative bacteria

A

outer leaflet: endotoxin (LPS/LOS)
- lipid A induces TNF and IL1

embedded proteins
- porins: transport across outer membrance (transmission of substances)

inner leafleft: phospholipids

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6
Q

difference in outer cell wall between gram - and gram + bacteria

A

gram neg bacteria
- outer membrane
- periplasm (space between cytoplasmis membrane and outer membrane, peptidoglycan is in the middle) - hydrolytic enzymes can accumulate here as they exit

gram pos
- larger cell wall

both have cell walls made up of peptidoglycan sugar backbones with peptide side chains
- rigid support
- protection against osmotic pressure damage

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7
Q

composition of cytoplasmic membrane

A

phospholipid bilayer sac with embedded proteins
- penicillin binding proteins > help with cell wall synthesis
- lipoteichoic acids (gram + only) extend from membrane to outer exterior (induce TNFa and IL1)
- site of oxidative and transport enzymes

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8
Q

explain gram staining

A
  • crystal violent stain is applied
  • iodine (fixes stain)
  • alcohol (decolorizer; gram POS still retain violet dye due to their THICK peptidoglycan layer)
  • counterstain > gram NEG appear red/pink
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9
Q

what are spores?

A
  • only occur in gram POS bacteria (bacillus, clostridium)
  • kertain-like coat, contains peptidoglycan, and DNA
  • helps resist dehydration, heat, and chemicals
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10
Q

what are the urease positive organisms?

A

Pee CHUNKSS
- proteus
- cryptococcus
- H pylori
- Ureaplasma
- Nocardia
- Klebsiella
- S epidermidis
- S saprophyticus

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11
Q

positive versus negative stains

A

positive
- basic
- bacteria are neg (proteins)
- take up pos stain
- bacteria will be in color under microscopy
- ex: methalene blue

negative
- acidic
- bacteria are neg
- repel neg stain
- bacteria will be white/clear w color background under microscopy
- ex: india ink, nigrosin

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12
Q

what bacteria can not gram stain and why?

A

These Little
Microbes
May Unfortunately
Lack Real Color, But Are Everywhere

  • Treponema, Leptospira (too thin)
  • Mycobacteria (cell wall with high lipid content)
  • Mycoplasma, Ureaplasma (no cell wall)
  • Legionella, Rickettsia, Chlamydia, Bartonella, Anaplasma, Ehrlichia (intracellular)
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13
Q

what is an acid fast/ziehl-neelsen stain

A
  • stains acid fast bacteria (mycobacteria and nocardia)
  • uses carbol fuchsin > turns bacteria red
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14
Q

what is choc agar

A

heated up blood agar
IDs H flu

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15
Q

what is macconkey agar

A
  • fermentation produces acids
  • colonies turn pink
  • lactose-fermenting bacteria (enteric gram NEG) > colorless colonies
    -** lactose fermenters (e coli, citrobacter, klebsiella, enterobacter) > pink colonies**
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16
Q

what is eosin-methylene blue (EMB) agar

A

colonies have green metallic stain
IDs: E coli

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17
Q

what is sabouraud agar

A

fungi exclusively; too acidic for bacteria

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18
Q

what are anaerobes? give examples

A

Cant Breathe Fresh Air
- clostridium
- bacteroides
- fusobacterium
- actinomyces israelii

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19
Q

what are the obligate intracellular bacteria

A

stay inside when its Really Chilld and Cold

  • rickettsia
  • chlamydia
  • coxiella
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20
Q

what are the facultative intracellular bacteria

A

Some Nasty Bugs May Live FacultativeLY
- salmonella
- neisseria
- brucella
- mycobacterium
- listeria
- francisella
- legionella
- yersinia pestis

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21
Q

what does catalase do?

A

degrades H2O2 into water and oxygen; helps bacteria survive ROS

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22
Q

what are the catalase positive organisms?

A

Big cats Have BeeN to PLACESS

  • bordatella pertussis
  • h pylori
  • burkholderia cepacia
  • nocardia
  • pseudomonas
  • listeria
  • aspergillus
  • candida
  • e coli
  • serratia
  • staphylococci
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23
Q

staphlycocci general characteristics

A
  • skin/mucous membranes
  • spherical cells in irregular clusters
  • gram pos
  • lack spores/flagella
  • may have capsules
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24
Q

staph aureus effects, if any, on:
skin/skeletal

A
  • boils, carbuncles
  • impetigo
  • scalded skin syndrome
  • osteomyelitis
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25
staph aureus effects, if any, on: CV, lymphatic, systemic
- endocarditis - TSS
26
staph aureus effects, if any, on: GI
food intoxication
27
staph aureus effects, if any, on: respiratory
pneumonia
28
coag-neg staph effects, if any, on: skin/skeletal
surgical infections
29
coag-neg staph effects, if any, on: CV/lymphatic/systemic
endocarditis
30
coag-neg staph effects, if any, on: urogenital
UTIs
31
strep pyrogenes (group A) effects, if any, on: skin/skeletal
- pyoderma (impetigo) - erysipelas - necrotizing fasciitis
32
strep pyrogenes (group A) effects, if any, on: CV/lymphatic/systemic
- scarlet fever - rheumatic fever
33
strep pyrogenes (group A) effects, if any, on: respiratory
- pharyngitis (strep throat) - sinusitis
34
strep pyrogenes (group A) effects, if any, on: urogenital
glomerulonephritis
35
strep agalactiae (group B) effects, if any, on: skin/skeletal
wound infections
36
strep agalactiae (group B) effects, if any, on: nervous/muscle
neonatal meningitis
37
strep agalactiae (group B) effects, if any, on: CV/lymphatic/systemic
- neonatal sepsis - endocarditis
38
strep agalactiae (group B) effects, if any, on: respiratory
neonatal pneumonia
39
enterococci effects, if any, on: skin/skeletal
wound and surgical infections
40
enterococci effects, if any, on: urogenital
healthcare associated UTIs
41
strep viridans effects, if any, on: CV/lymphatic/systemic
subacute endocarditis
42
strep viridans effects, if any, on: GI
dental caries
43
strep pneumoniae effects, if any, on: nervous/muscle
pneumococcal meningitis (adult)
44
strep pneumoniae effects, if any, on: respiratory
- pneumonia - otitis media - sinusitis
45
neisseria gonorrhoeae effects, if any, on: skin/skeletal
gonococcal opthalmia
46
neisseria gonorrhoeae effects, if any, on: urogenital
gonorrhea
47
neisseria meningitidis effects, if any, on: nevous/muscle
meningococcal meningitis
48
staphylcoccus aureus general characteristics
- grows in large, round, opaque colonies - facultative anaerobe - withstands high salt, pH extremes, high temps - produces many virulence factors
49
staphylcoccus aureus epidemiology/pathogenesis
- present in most environments frequented by humans - readily isolated from fomites - 20-60% in healthy adults in ant nares, skin, nasopharynx, intestine - inc in community acquired methicillin resistance (MRSA) - predisposition to infection: poor hygiene and nutrition, tissue injury, pre-existing primary infection, diabetes, immunodeficiency
50
staph aureus pathology
- localized skin infections (folliculitis, furuncle, carbuncle, impetigo) - osteomyelitis - bacteremia (>endocarditis) - toxigenic dz (food intoxication, scalded skin syndrome, TSS)
51
coagulase negative staphylococci
healthcare associated and opportunistic infections in immunocompromised pts - S epidermidis - skin and mucus membranes (endocarditis, bacteremia, UTI) - S hominis - around apocrine sweat glands - S capitis - around scalp, face, external ear all three above can cause wound infections by penetrating through broken skin - S saprophyticus - infrequently lives on skin, intestine, vagina, UTI
52
what differentiates staph aureus from other staph species?
coagulase POS
53
streptococci general characteristics
- gram pos spherical/ovoid cocci in long chains, usu pairs - non spore forming, non motile - can form capsules and slime layers - faculatative anaerobes - no catalase, but have peroxidase system - small, nonpigmented colonies - sensitive to drying, heat, disinfectants - most parasitic forms are fastidious and require enriched media
54
streptococcus subspecies breakdown
beta hemomlytic - bacitracin sensitive: group A strep (pyogenes) - bacitracin resistant: group B, C strep alpha hemolytic - optochin sensitive: strep pneumoniae - optochin resistant: group D, viridans strep
55
strep pyogenes hemolysis type habitat pathology
beta hemolytic human throat skin, throat infections, scarlet fever
56
strep agalactiae hemolysis type habitat pathology
beta hemolytic human vagina, cow udder neonatal, wound infections
57
Strep equi hemolysis type habitat pathology
beta hemolytic various mammals rare; abscesses
58
Strep dysgalactiae hemolysis type habitat pathology
beta hemolytic cattle rare
59
enterococcus faecalis hemolysis type habitat pathology
alpha, beta, N hemolytic human, animal intestine endocarditis, UTI
60
E faecium, E durans hemolysis type habitat pathology
alpha hemolytic human, animal intestine endocarditis, UTI
61
strep bovis hemolysis type habitat pathology
no hemolysis cattle subacute endocarditis, bacteremia
62
Strep sanguinis hemolysis type habitat pathology
alpha hemolytic human oral cavity endocarditis
63
strep mutans hemolysis type habitat pathology
no hemolysis human oral cavity dental caries
64
Strep pneumoniae hemolysis type habitat pathology
alpha hemolytic human respiratory tract bacterial pneumonia
65
Strep anginosus hemolysis type habitat pathology
beta hemolytic humans, dogs endocarditis, URT infections
66
strep salivarius hemolysis type habitat pathology
no hemolysis human saliva endocarditis
67
strep pyogenes surface antigens
- C carbohydrates: protects against lysozymes - fimbriae: adherence - M protein: resistance to phagocytosis - Hyluronic acid capsule: provokes no immune response - C5a protease: hinders complement and neutrophil response
68
strep pyogenes major extracellular toxins
- streptolysins (hemolysins): streptolysin O (SLO) and streptolysis (SLS); both cause cell and tissue injury - erythrogenic toxin (pyrogenic) - induces fever and typical red rash - superantigens - strong monocyte and lymphocyte stimulants; cause release of tissue necrosis factor
69
strep pyogenes extracellular enzymes
- streptokinase: digests fibrin clots - hyluronidase: breaks down CT - DNase - hydrolyzes DNA
70
strep pyogenes epidemiology and pathogenesis
- humans only reservoir - unapparent carriers - transmission: contact, droplets, food, fomites - portal of entry generally skin or pharynx - children predominant group for cutaneous and thraot infxns - sys infxn and progressive sequelae possible if untreated
71
strep pyogenes pathology
- skin infections (impetigo/pyoderma, **erysipelas**) - throat infections - systemic infections (scarlet fever via erythrogenic toxin, septicemia, TSS)
72
strep pyogenes/group A strep long-term complications
- rheumatic fever: follows overt or subclinical pharyngitis in kids, carditis with extensive valve damage, arthritis, chorea, fever - acute glomerulonephritis (PSGN): nephritis, inc BP, occ HF, can become chronic > kidney failure
73
strep agalactiae/Group B strep location, transmission, pathology
- resides in human vagina, pharynx, large intestine - can be transferred to infant during delivery and cause neonatal pneumonia, sepsis, and meningitis - wound and skin infections and endocarditis in immunocompromised people
74
group D strep name location pathology
* enterococus faecalis, e faecium, e durans * normal colonists of human large intestine * cause opportunistic urinary, wound, and skin infections, esp in immunocompromised ppl
75
groups C and G strep location pathology
- common animal flora, frequently isolate from upper respiratory - pharyngitis, glomerulonephritis, bacteremia
76
strep viridans general information
- gums, teeth, oral cavity; nasopharynx, genital tract, skin - alpha hemolytic - not very invasive; dental/surgical procedures facilitate entrance - strep mutans, oralis, salivarus, sanguis, milleri, mitis
77
strep viridans pathology
bacteremia, meningitis, abdominal infection, tooth abscesses subacute endocarditis - blood bourne bacteria settle and grow on heart lining or valves - ppl with preexisting heart dz at high risk - colonization of heart by forming biofilms
78
strep mutans pathology
slime layers that adhere to teeth > basis of plaque - dental caries - give ppl with preexisting heart conditions prophylactic antibiotics before surgery or dental procedures
79
strep pneumoniae details and pathology
- small, lanclet shaped cells in pairs and short chains - lack catalase and peroxidase (cultures die in O2) - culture requires blood or chocolate agar - causes 60-70% of bacterial pneumonias, - otitis media
80

NPLEX I 2024 (23 decks)

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