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Microbiology > Gram (-) > Flashcards

Gram (-) Flashcards

1
Q

gram (-) - colour

A

pink

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2
Q

Gram (-) - subgroups

A
  1. diplococci
  2. coccoid robs (cocciobacilly)
  3. robs
  4. oxidase (+) comma shaped robs
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3
Q

Gram (-) - subgroups - diplococci - bugs and maltose

A
  1. Neisseria meningitis (malose)
  2. Neisseria gonorrhoeae (non-maltose)
  3. Moraxella catarrhalis (non-maltose)
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4
Q

Gram (-) - subgroups - diplococci - neisseria - bugs (and characteristics

A
  1. Neisseria meningitis (maltose fermenter, polysaccharide capsule, glucose fermenter)
  2. Neisseria gonorrhoeae (maltose nonfermenter, no capsule, glucose fermenter)
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5
Q

Gram (-) - subgroups - coccoid robs - bugs?

A
  1. haemophilus infleunzae
  2. Pasteurella
  3. Brucella
  4. Bordetella pertusis
  5. Francicella tularencis
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6
Q

Pasteurella - transmission by

A

animal bite

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7
Q

H. influenza - media (and its contains)?

A

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

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8
Q

Gram (-) - subgroups - oxidase +, comma shape

A
  1. Campylobacter jejuni (grows in 42c, oxidase +, comma shape)
  2. Vibrio cholera (grows in alkaline media, oxidase +, comma shape)
  3. Helicobacter pylori (produces urease, oxidase +, comma shape, catalase +)
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9
Q

Gram (-) stain robs are divided to (only the groups)

A
  1. Lactose fermeter

2. Lactose nonfermenter

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10
Q

Gram (-) stain robs - Lactose nonfermenter are divided to

A

oxidase -

oxidase +

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11
Q

Gram (-) stain robs - oxidase (+) Lactose nonfermenter - bugs (and their characeristic)

A

Pseudomonas - rob, oxidase (+),

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12
Q

Gram (-) stain robs - oxidase (-) Lactose nonfermenter - are divided to

A

H2S producers and non producers (TSI AGAR)

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13
Q

Gram (-) stain robs - oxidase (-) Lactose nonfermenter - bags and their characteristics

A
  1. Salmonela - lacose nonfermeter, oxidase -, H2S producer
  2. Proteus - lacose nonfermeter, oxidase -, H2S producer
  3. Yersinia - lacose nonfermeter, oxidase -, not H2S producer
  4. Shigella - lacose nonfermeter, oxidase -, not H2S producer
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14
Q

Gram (-) stain robs - lactose non fermenter bugs

A
  1. pseudomonas
  2. shigella
  3. salmonella
  4. proteus
  5. Yersinia
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15
Q

Gram (-) stain robs - lactose fermenter bugs (and characteristics)

A
  1. klebsiella (rob, fast lactose fermenter)
  2. E. coil (rob, fast lactose fermenter)
  3. Enterobacter (rob, fast lactose fermenter)
  4. citrobacter (rob, slow lactose fermenter)
  5. serratia (rob, fast lactose fermenter)
  6. others (rob, fast lactose fermenter)
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16
Q

Gram (-) stain robs - lactose fermenter are divided to

A

fast and slow fermenters

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17
Q

Gram (-) stain - lactose fermatation - appearance

A

fermantation of lactose –> fermentation produces acid pink colonies on MacConkey agar

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18
Q

lactose fermatation - agar?

A

MacConkey agar

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19
Q

E. coli is a lactose fermenter - mechanism

A

E. coli produces β-galactosidae, which breaks down lactose into glucose and galactose

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20
Q

EMB

A

eosin-methylane blue agar

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21
Q

EMB - lactose fermenting bacteria –>

A

lactose fermenters grow as purple/black colonies

E. coli grows colonies with a green sheen

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22
Q

Neisseria - media (and its contains)?

A

Thayer - Martin - vancomicin , trimethoprim, colistin , nystatin

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23
Q

Thayer - Martin contains … (and action)

A
  1. vancomicin –> inhibits gram (+)
  2. trimethoprim
  3. colistin –> inhibits gram (-) except Neisseria
  4. nystatin –> inhibits fungi
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24
Q

neisseria produce (virulence factor)

A

IgA protease

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25
Q

neisseria gonococci vs neisseria meningitis - capsule

A

neisseria gonococci –> no capsule

neisseria meningitis –> polysaccharide capsule

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26
Q

neisseria gonococci vs neisseria meningitis - maltose fermentation

A

neisseria gonococci –> no

neisseria meningitis –> yes

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27
Q

neisseria gonococci vs neisseria meningitis - vaccines

A

neisseria gonococci –> no

neisseria meningitis –> yes (type B not widely available)

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28
Q

neisseria gonococci vs neisseria meningitis - transmission (via)

A

neisseria gonococci –> sexual or perinatally

neisseria meningitis –> respiratory or oral secretions

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29
Q

neisseria gonococci vs neisseria meningitis - manifestations

A

neisseria gonococci –> 1. gonorrhea, 2. septic arthritis, 3. neonatal conjunctivitis, 4. PID, 5. Fitz-Hugh-Curris syndrome, 6. prostatitis, 7. epididymitis, 8. osteomyelitis (RARE)
neisseria meningitis –>1. meningococcemia with petechial hemor and gangrene of toes, 2. meningitis, Waterhouse-Friderichsen syndrome (adrenal insuf, fecer, DIC)

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30
Q

neisseria gonococci vs neisseria meningitis - prevention

A

neisseria gonococci –> condoms (for STD), erythromycin ointment (neonatal transmision)
neisseria meningitis –> Rifampin, ciprofloxacin or ceftriaxone prophylaxis in close contacts

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31
Q

neisseria gonococci vs neisseria meningitis - treatment

A

neisseria gonococci –> ceftriaxone + (azithromycin or doxycycline) for possible chlamydial coinfection
neisseria meningitis –> ceftraxone or penicillin G

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32
Q

neisseria gonococci vs neisseria meningitis - intracellular

A

neisseria gonococci –> yes

neisseria meningitis –> no

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33
Q

neisseria gonococci - vaccination

A

no –> due to antigenic variation of pilus proteins

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34
Q

MC complications in men and women of gonococcal urethritis

A

men: epididymitis, prostatitis, urethral strictures
women: sterility, ectopic pregnancy, peritonitis, perihepatitis

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35
Q

what type of immunodeficiency has the greatest risk of N. meningitides bacteremia

A

C6-C9 deficiency

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36
Q

Waterhouse-Friderichsen syndrome?

A

fulminant meningococcemia leading to septic shock and bilateral adrenal hemorrhage causing catastrophic adrenal insufficiency and deaths in hours

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37
Q

Gram (-) - subgroups - coccoid robs - bugs?

A
  1. haemophilus infleunzae
  2. Pasteurella
  3. Brucella
  4. Bordetella pertusis
  5. Francicella tularencis
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38
Q

haemophilus infleunzae - characteristics

A

small gram (-) coccoid robs (coccobacillary)

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39
Q

haemophilus infleunzae - transmission

A

aerosol transmission

40
Q

H. influenza - media (and its contains)?

A

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

41
Q

H. influenza - stains (clinical relevance)

A
  1. Nontypeable stains (non-vaccine)

2. tybe b stain (vaccine)

42
Q

Nontypeable stains are the MCC of

A

A. mucosal infection:

  1. otitis media
  2. conjunctivitis
  3. bronhitis
43
Q

H. influenza produces

A

IgA protease

44
Q

H. influenza can also be grown with …..

A

S. aureus, which provides factor V (NAD+) through the hemolysis of RBCs.

45
Q

en-capsuled type B H. influenza causes

A

invasive infection:

  1. meningitis
  2. acute epiglottitis (children)
  3. septic arthritis
  4. sepsis
46
Q

acute epiglottitis - appearance

A

endoscopy: cheery red

x-ray: thumbprint signs (thickening of epiglottis on lateral neck radiograph)

47
Q

H. influenza - treatment

A
  1. mucosal infection –> amoxicillin +/- clavulanate

2. meningitis –> ceftriaxon.

48
Q

H. influenza - prophylaxis in close contacts

49
Q

H. influenza - prevention / given when

A

vaccine contains type b capsular polysaccharide and PRP (polyribosylribitol phosphate) conjugated to diptheria or other protein
given between 2 and 18 monthes of age

50
Q

Legionella pneumonophila - characteristics

A

gram (-), –> gram stains poorly

51
Q

Legionella pneumonophila - staining

A

gram ((-)) stains poorly –> SILVER STAIN

52
Q

silver stain is used to stain

A
  1. Fungi (eg. Pneumocytosis)
  2. Legionella
  3. Helicobacter pylori
53
Q

Legionella - media?

A

charcoal yeast extract agar buffered with cysteine and iron

54
Q

Legionella - detection

A
  1. by presence of antigen in urine

2. Labs may show hyponatremia

55
Q

Legionella - transmission

A

–> aerosol transmission from environmental water source habitat (eg. air condition systems, hot water tanks)
(NO PERSON - PERSON)

56
Q

Legionella - treatment

A

macrolide or quinolone

57
Q

Legionella pneumophilla –> ….

A
  1. Legionnaires’s disease

2. Pontiac fever

58
Q

Legionnaires’s disease?

A

severe pneumonia (often unilateral and lobar), fever, GI and CNS symptoms

59
Q

Pontiac fever is caused by / manifestation

A
  • Legionella pneumophilla

- mild flu-like syndrome

60
Q

risk factors for Legionnaires’s disease

A
  1. Cigarette smoking
  2. alcoholics
  3. chronic lung disease
  4. immunosuppressed states
61
Q

Pseudomonas aeroginosa - characteristics

A

Aerobic, motile, gram (-) rob, Non lactose fermenting, oxidase (+)

62
Q

Pseudomonas aeroginosa - oxidase? / lactose?

A
  • oxidase +

- Non lactose fermenting

63
Q

Pseudomonas aeroginosa - appearance

A
  1. pyocacin (blue-green pigment)

2. grape-like odor

64
Q

Pseudomonas aeroginosa - mechanism of action

A

produce

  1. endotoxin –> fever + shock
  2. exotoxin A –> inactivates EF-2
  3. pyocacin –> generates ROS
65
Q

pseudomonas aeroginosa - manifestations (and associated conditions)

A
  1. Pneumonia (Cystic fibrosis, mechanical ventilation)
  2. otitis externa - swimmer’s ear (diabetes)
  3. UTI (hospital patients)
  4. ecthyma gangrenosum (immunocompromised patients)
  5. sepsis
  6. osteomyelitis (eg. puncture wounds, drug use)
  7. wound infection (burn victim)
  8. hot tub folliculitis (water)
    9 nosocomial infections (catheter equipment)
66
Q

ecthyma gangrenosum - definition and appearance

A

rapidly progressive necrotic lesion caused by pseudomonas aeroginosa. Large ulcers with necrotic regions. Typically seen in immunocompromised patients

67
Q

conditions associated with pseudomonas aeroginosa infection

A
  1. Cystic fibrosis
  2. mechanical ventilation
  3. hospital
  4. immunodeficiency
  5. puncture wounds
  6. drug use
  7. water
  8. burn victim
68
Q

pseudomonas aeroginosa - pneumonia - mechanism of action

A

Mucoid polysaccharide capsule may contribute t ochronic pneumonia in cystic fibrosis patietns due to biofilm formation

69
Q

Pseudomonas aeroginosa - treatment

A
  1. extended spectrum β-lactams (eg piperacillin, ticarcillin, cafepime)
  2. Carbapenems (eg imipenem, meropenem)
  3. Monobactams (eg aztreonam)
  4. Fluoroquinolones (eg ciprofloxacin)
  5. Aminoglycosides (eg. gentamycin, tobramicin)
  6. For multidrug resistant stains –> colistin, polymyxin B
  7. 3rd and 4th generation cephalosporines
70
Q

Pseudomonas aeroginosa - treatment for multidrug resistant stains

A

colistin

polymyxin B

71
Q

Pseudomonas aeroginosa - otitis externa - swimmer’s ear is associated with

72
Q

Pseudomonas aeroginosa - UTI is associated with

A

hospital patients

73
Q

Pseudomonas aeroginosa - osteomyelitis is associated with

A

puncture wounds, drug use

74
Q

Pseudomonas aeroginosa - wound infection is associated with

A

burn victim

75
Q

Pseudomonas aeroginosa - hot tub folliculitis is associated with

76
Q

Pseudomonas aeroginosa - eye

A

it can cause corneal ulcer in contact lens wearers

77
Q

E coli - virulence factors and associated diseases

A
  1. fibmbriae –> cystitis and polynephritis (P-pili)
  2. capsule (K) –> pneumonia, neonatal meningitis
  3. LPS –> septic shock
78
Q

E coli - strains

A
  1. EIEC (Enteroinvasive)
  2. ETEC (Enterotoxigenic)
  3. EPEC (Enteropathogenic)
  4. EHEC (Enterohemorrhagic)
79
Q

EIEC (Enteroinvasive) - toxins and mechanism

A

main virulence factors by plasmid shared by shigella –> proteins for adherence and direct invasion (no toxins) invades intestinal mucosa and causes necrosis and inflammation

80
Q

EIEC (Enteroinvasive) - presentation

A

dysentery with white blodd cells
fever
(similar to shigella)

81
Q

ETEC (Enterotoxigenic) - main virulence factors

A

produce heat-labile and heat stable toxin enterotoxins

NO INFLAMMATION OR INVASION

82
Q

ETEC (Enterotoxigenic) - presentation

A

traveler’s diarrhea (watery)

83
Q

Head-labile toxin (LT) - mechanism of action

A

Overactivates adenylate cyclase (increases cAMP) –> increases CL- secretion in gut and H20 efflux

84
Q

Head-stable toxin (ST) - mechanism of action

A

overactivates guanylate cyclase (increases cGMP) –> decreases resorption of NaCL and H20 in gut

85
Q

EPEC (Enteropathogenic) - toxins and mechanism

A

No toxins

Adheres to apical surface, flattens villi –> prevent absorption

86
Q

EPEC (Enteropathogenic) - presentation

A

watery diarrhea, usually in children

87
Q

EHEC (Enterohemorrhagic) - toxin and mechanism

A

shiga - like toxin –>

a. enhances cytokines release –> hemolytic uremic syndrome
b. GI mucosa damage –> dysentery

88
Q

Shiga like toxin - mechanism of action

A

inactivates 60S ribosome by removing adenine from rRNA

89
Q

hemolytic uremic syndrome –>

A

triad of anemia, thrombocytopenia and acute renal failure due to microthrombi forming on damage enthothelium –> mechanical hemolysis (schistocytes on peripheral smear, platelet consumption, and decreased renal flow

90
Q

EHEC (Enterohemorrhagic) - presentation

A
  1. dysentery (toxin alone causes necrosis and inflammation)

2. triad of hemolytic uremic syndrome (anemia, thrombocytopenia and acute renal failure)

91
Q

hemolytic uremic syndrome - peripheral smear

A

schistocytes

92
Q

EHEC (Enterohemorrhagic) is also called / MC serotype is US

A

STEC (shiga toxin-producing E. col)

O157:H7

93
Q

E-coli is a lactose fermenter - mechanism

A

E. coli produces β-galactosidae, which breaks down lactose into glucose and galactose

94
Q

how to distinguish EHEC from other E. coli

A

EHEC does not ferment sorbitol

95
Q

E. coli - presentation

A
  1. EIEC –> dysentery with white blood cells, fever
  2. ETEC –> traveler’s diarrhea (watery)
  3. EPEC –> watery diarrhea, usually in children
  4. EHEC –> dysentery, hemolytic uremic syndrome
96
Q

EHEC - trasnmission

A

undercooked meat, raw leafy vegetables

Microbiology (25 decks)

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