Aerobic Gram Pos Rods Flashcards
(114 cards)
0
Q
Corynebacterium normal flora of…
A
Skin and mucous membranes
1
Q
Gram stain of Corynebacterium
A
Gram positive rods in chinese letter formation (coryneform)
2
Q
Corynebacterium diptheriae catalase reaction
A
Positive
3
Q
Corynebacterium diptheriae is resistant to…
A
Drying
4
Q
Corynebacterium diptheriae is readily killed by…
A
heat and most disinfectants
5
Q
Diptheria toxin
1) Type of toxin
2) Produced only by stains with…
A
1) Exotoxin
2) Produced by strains infected with bacteriophage
6
Q
How can nontoxigenic strains of Corynebacterium diptheriae be converted to a toxigenic strain?
A
Infected with bacteriophage
7
Q
What amino acid is required in order for C. diptheriae to become toxigenic and why?
A
Trypsin; Splits the AB portions of the exotoxin
8
Q
A portion of diphtheria toxin
1) Purpose
A
1) Disrupts protein synthesis and causes symptoms
9
Q
B portion of the diphtheria toxin
1) Purpose
A
1) Bind to receptors on eukaryotic cells to mediate entry of the A portion
10
Q
C. diptheriae
1) Types of infection
2) Transmission
3) Incubation
4) Treatment
A
1) Respiratory and cutaneous forms
2) Droplet or hand-to-mouth contact
3) 2-5 days
4) Antitoxin
11
Q
C. diptheriae
1) What is the main symptom developed?
A
1) Pseudomembrane in the oropharnyx and tonsils
12
Q
C. diptheriae pseudomembrane
1) Composed of…
2) Main purpose of this membrane
A
1) Fibrins, WBCs, necrotic epithelial cells
2) Site where exotoxin is released in the bloodstream
13
Q
C. diptheriae pseudomembrane
1) What will occur if you remove the pseudomembrane?
A
Toxin will increase at an increased rate
14
Q
C. diptheriae
1) Babes-Ernst granules
A
1) Metachromatic areas of the cell which stain more intensely (storage deposits for bacteria)
15
Q
What type of media will better culture C. diphtheria?
A
Loeffler medium
Tinsdale agar
Tellurite media
Cystine-Tellurite Blood agar
16
Q
How does Loeffler media help to distinguish C. diphtheriae?
A
Enhances the Babes-Ernst granules
17
Q
How does Tinsdale agar help to differentiate C. diptheriae?
A
Grey to black colonies with a brown halo
18
Q
How does Cystine-Tellurite blood agar differentiate C. diptheriae?
A
Brown to black colonies
19
Q
What stain will help differentiate C. diptheriae?
A
Loeffler methylene blue–helps to distinguish the metachromatic granules and will show reddish/purple granules
20
Q
What are the three biotypes of C. diptheriae?
A
Gravis colonies
Mitis colonies
Intermedius colonies
21
Q
C. diptheriae Gravis colonies
A
Large dark gray, centrally matte, irregular colonies
22
Q
C. diptheriae Mitis colonies
A
Small black, convex, entire colonies
23
Q
C. diptheriae Intermedius colonies
A
Very small, flat, dry, gray, or black colonies
24
How can one reach a definitive ID of C. diptheriae?
Requires demonstration of toxin production by the isolate in question; patient may be infected with several strains at once so testing is performed using pooled inoculum of at least 10 colonies
25
C. diptheriae Elek Test
Must use a (-) and (+) control.
| Positive reaction will show lines of precipitation along the diptheria antitoxin
26
What are some other ways to detect the toxin of C. diptheriae?
Elek test
Guinea pig lethality test
Tissue culture cell test
PCR to detect toxin gene
27
How is C. diptheriae treated?
Prompt neutralization of toxin, followed by the eradication of the organism
28
Why are antibiotics not recommended for treatment of C. diptheriae?
They have no effect on circulating toxin, just eliminate pool of organisms and prevent spread
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How is C. diptheriae prevented?
DPT vaccine
30
Corynebacterium jeikeium
1) Most common skin flora of...
2) Virulence level
3) Diseases
4) Main virulence factor
1) Hospitalized patients (immunocompromised)
2) Low
3) Septicemia, wounds, rarely endocarditis
4) Highly resistant to antibiotics
31
Main disease of C. jeikeium?
Septicemia (life threatening)
32
What is the main risk factor for C. jeikeium?
Colonization of intravenous catheters
33
Arcanobacteruim hemolyticum
1) Epidemiology
2) Transmission
3) Clinical infection
1) Normal flora of human skin and pharynx
2) Uncertain (probably endogenous)
3) Pharyngitis, cellulitis, other skin infections
34
Arcanobacteruim hemolyticum grows on what media?
BAP and CHOC
35
Arcanobacteruim hemolyticum colony morphology
Small colonies with various appearance, may be surrounded y narrow zone of beta hemolysis
36
What can Arcanobacteruim hemolyticum colonies resemble and how can a microbiologist differentiate?
Beta strep; Will try to strep type the beta hemolytic colonies and will type (-); gram stain will show GPR
37
Arcanobacteruim hemolyticum catalase reaction
Negative
38
Treatment for Arcanobacteruim hemolyticum
Susceptibility to penicillin erythromycin, and clindamycin
39
Listeria monocytogenes
| 1) Epidemiology
1) Widely distributed in nature; human and animal pathogen
40
Where does Listeria monocytogenes colonize in humans?
GI tract
41
Listeria monocytogenes pathogenesis
```
Listeriolysin O (hemolysin)
Endotoxin
```
42
Listeriolysin O (hemolysin)
1) Type of toxin
2) Only present in what strains?
1) Membrane damaging toxin
| 2) Virulent strains
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Listeria monocytogenes internalin
Allows Listeria monocytogenes to penetrate cells faster
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Listeria monocytogenes surface protein p60
Induces phagocytosis through increased adhesion and penetration into mammalian cells
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Listeria monocytogenes virulent factors
```
Listeriolysin O
Endotoxin
Internalin
Superoxide dismutase
Phospholipase C
Surface protein p60
```
46
Listeriolysin O main purpose
Prevent phagocytosis
47
Listeria monocytogenes Transmission
Usually by ingestion of contaminated food, meat, or dairy or colonized mothers passing it to fetus
48
Listeriosis
1) Diagnostic test
2) Symptoms
1) Blood culture and spinal tap
| 2) Septicemia and meningitis
49
Listeria monocytogenes disease in pregnant women
1) What trimester?
2) Symptoms for the mother
3) Other consequences?
1) 3rd trimester
2) Flulike symptoms
3) spontaneous abortion and still births
50
Listeria monocytogenes disease in newborns
1) Early onset
2) Late onset
1) Intrauterine, causes sepsis at or shortly after birth
| 2) Full term and healthy at birth, causes meningitis
51
Other clinically significant diseases of Listeria monocytogenes
Granulomatous skin lesions
Lymphadenitis
Endocarditis
52
Source of diagnosis and testing for Listeria monocytogenes
Blood; CSF; lesions
53
Laboratory ID of Listeria monocytogenes
1) Colony morphology on BAP
2) Gram stain reaction
3) Catalase reaction
1) Small, smooth, translucent, beta hemolytic colonies
2) Slender, short gpr
3) Positive
54
What will the wet mount reveal of Listeria monocytogenes?
Distinctive tumbling motility in liquid media, especially after incubation at 25 C
55
At what unique temperature can Listeria monocytogenes grow?
4C (refrigeration)
56
What does Listeria monocytogenes resemble and how to differentiate?
Group B strep
| CAMP test will reveal a block formation rather than arrow head formation
57
Listeria monocytogenes
1) Bile esculin
2) Hippurate
3) CAMP test
4) Motility
1) Positive
2) Positive
3) Positive--block formation
4) Positive--umbrella
58
If the motility agar shows an umbrella formation, what organism does this indicate?
Listeria monocytogenes
59
What organism is best to perform the CAMP test with when testing for Listeria monocytogenes?
R. equi
60
Erysipelothrix rhusiopathiae epidemiology
Not part of normal flora
| Domestic swine is the major reservoir
61
Erysipelothrix rhusiopathiae transmission
Occupations: handling fish/animal products
| Infection through cuts or scratches
62
Erysipelothrix rhusiopathiae diease
Erysipeloid; cutaneous inflammatory disease usually of hands and fingers
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How is erysipeloid ID'd?
Culture biopsy
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Erysipelothrix rhusiopathiae media
BAP and CHOC
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Erysipelothrix rhusiopathiae main differentiating test
H2S positive on TSI or KIA slant
66
A brush pattern of growth is shown on a gelatin slab, what organism is causing this pattern?
Erysipelothrix rhusiopathiae
67
Erysipelothrix rhusiopathiae colony morphology
Smooth, small, transparent colonies showing greenish color
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Lactobacillus epidemiology
Environment, normal flora of mouth, GI, female genital tract
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Lactobacillus transmission
Endogenous (only relevant when predominant on the plates
70
Clinical significance of Lactobacillus
Contaminant
| Bacteremia in immunocompromised
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Lactobacillus colony morphology
Usually small and alpha hemolytic; ground-glass appearance
72
Lactobacillus gram morphology
Gram positive wispy rods
73
Lactobacillus catalase reaction
Negative
74
What is important about Lactobacillus when it comes to antimicrobials?
Highly resistant to vancomycin
75
Gardnerella vaginalis epidemiolgy
Normal vaginal flora
76
Gardnerella vaginalis clinical infection
Bacterial vaginosis
| UTI
77
What is the best agar to culture Gardnerella vaginalis? Why?
V agar; human blood; HPT agar
78
Colony morphology of Gardnerella vaginalis
Tiny pinpoint colonies, beta-hemolytic
79
Gram stain morphology of Gardnerella vaginalis
Small pleomorphic gram-variable or gram-negative coccobacilli and short rods; gram yucky
80
Gardnerella vaginalis catalase reaction
Negative
81
When is Gardnerella vaginalis considered pathogenic in a genital culture?
When it is predominant over lactobacillus
82
What growth must be compared to Gardnerella vaginalis and on what medium for it to be considered pathogenic?
Compare to lactobacillus no chocolate agar
83
What differences will be seen on chocolate agar when comparing Gardnerella vaginalis and lactobacillus?
Gardnerella vaginalis--tiny pinpoint, beta-hemolytic colonies
Lactobacillus--alpha colonies (greenish)
84
Direct detection of Gardnerella vaginalis
Wet prep and identification of "clue cells"
"Whiff test"
Probe test (vag probe)
85
Clue cells
ID Gardnerella vaginalis
| **Large, squamous epithelial cells with numerous attached organisms
86
DNA detection of Gardnerella vaginalis is based on?
Predetermined threshold for normal flora
87
A gram stain shows gram-positive bacilli with squared-off ends
Bacillus
88
Spores are seen on a gram stain with blocky bacilli
Bacillus
89
Bacillus anthracis pathogenesis
Glutamic acid capsule
| Exotoxins with three proteins (edema factor; lethal toxin; protective antigen)
90
Bacillus anthracis
| *Edema factor
Impairs neutrophil functin and causes massive edema
91
Bacillus anthracis
| **Lethal toxin
Stimulates macrophages to release tumor necrosis factor and interleukin IB
92
Bacillus anthracis
| **Protective antigen
Promotes entry of edema factor into phagocytic cells
93
What is the major reason for mortality when people are colonized with Bacillus anthracis?
Extoxins
94
What is required for Bacillus anthracis to be pathogenic?
Only pathogenic when the edema factor, lethal toxin, and protective antigen are together
95
How do the spores of Bacillus anthracis work?
They only activate at 37C or when they enter the host. They then are phagocytized by macrophages and become gram positive rods and reproduce in the lymphatic system. They then enter the bloodstream and cause sepsis.
96
How are humans infected with anthrax?
Animal products or contaminated dust
97
Can anthrax be transmitted to human to human?
No
98
What is the major cause of anthrax infection?
Imported goat hair
99
Cutaneous anthrax
1) Entry point
2) Symptom
3) Test for...
1) Cut or abrasion on skin
2) Black eschar (malignant pustule)
3) Serous fluid from below the black eschar
100
Inhalation Anthrax
1) Entry
2) Symptoms
3) Testing
1) Spores inhaled into the pulmonary parenchyma
2) Respiratory symptoms accompanied by disorientation, coma and death
3) Nasal swab (heat shock first); will see swelling around the heart in chest xray
101
Gastrointestinal anthrax
1) Entry
2) Symptoms
3) Testing
1) Spores inoculated into lesion on intestinal mucosa after ingestion
2) Abdominal pain, nausea, anorexia, vomiting, blood diarrhea
3) Gastric aspirates or stool
102
Why is GI anthrax have a higher mortality rate than the others?
Difficult to diagnose
103
Bacillus anthracis growth on what media?
BAP, CHOC, blood culture media
104
Bacillus anthracis colony morphology
Green, grey, frosted glass colonies
105
What is unique about Bacillus anthracis colony morphology
Medusa head and taffy like when picked up with a stick
106
Bacillus anthracis
1) Catalase reaction
2) Motility
3) Glucose
4) Penicillin
1) Positive
2) Nonmotile
3) Ferments glucose
4) Sensitive
107
Bacillus cereus epidemiology
environmental
108
Bacillus cereus transmission
Ingestion of contaminated food with spores or toxins
109
Bacillus cereus pathogenesis
Food poisoning (diarrheal type; emetic type (vomiting))
110
Bacillus cereus virulence factors
Enterotoxins (cramping and diarrhea)
111
Bacillus cereus enterotoxins
1) Heat-labile
2) Heat-stable
1) Nausea, abdominal pain and diarrhea, lasting 12-24 hours, JUST DIARRHEA
2) Short incubation followed by severe nausea and vomiting, with limited diarrhea (emetic toxin--vomiting within 6 hours)
112
Bacillus cereus laboratory ID
1) Hemolysis
2) Motility
3) What to culture?
1) Beta
2) Motile
3) Culture the suspected food and stool
113
What two organisms are most commonly used as autoclave/sterilizer checks?
B. subtilis and B. stearothermophilus
