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Quiz 3 Microbiology > Anaerobic infections and normal flora > Flashcards

Anaerobic infections and normal flora Flashcards

1
Q

What are common symptoms of anaerobic infections?

A

foul-smelling discharge from short-chain fatty acids and gas in the necrotic tissue

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2
Q

Where will you most commonly find anaerobic infections?

A

deep or necrotic tissue, where oxygen tension is low

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3
Q

Are most anaerobic infections mixed or does a single organism infect a tissue?

A

Usually anaerobic/microaerophilic infections=mixed or polymicrobial
Aerobic organisms = single species

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4
Q

Most anaerobic infections are caused by bugs found where?

A

In the patient’s endogenous flora

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5
Q

Bacteroides fragilis can be found in infections located in what general area of the body?

A

Infections below the diaphragm.

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6
Q

How long does it take to culture anaerobic organisms?

A

> 48 hrs

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7
Q

What is the typical morphology of species infecting the mouth? Are they sensitive or resistant to penicillin?

A

gram-positive cocci, gram-negative rods, mixed anaerobic infections.
These are sensitive to penicillin

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8
Q

What is the typical morphology of species infecting the abdominal area? Are they sensitive or resistant to penicillin?

A

gram-negative rods, mixed anaerobes

Penicillin resistant

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9
Q

How would you identify clinically important anaerobic bacteria?

A

Gram stain and morphology, production of unusual fatty acids

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10
Q

What are the anaerobic gram negative rods?

A

Bacteroides fragilis
Prevotella melaninogenicus
Fusobacterium species

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11
Q

Is B fragilis penicillin resistant or sensitive?

A

RESISTANT

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12
Q

If a patient has gram negative septicemia, the causative organism is most likely to be:

A

clostridium perfringens OR B. Fragilis

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13
Q

What is the most ommon anaerobic gram negative rod?

A

B fragilis

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14
Q

What is a major virulence factor of B fragilis?

A

The capsule

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15
Q

What is a common cause of B fragilis infection?

A

intraabdominal bowel rupture and female genital infections following procedures

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16
Q

Prevotella melaninogenicus is a common cause of:

A

oral infections–causing periodontal disease

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17
Q

What is prevotella melaninogenicus sensitive to?

A

Penicillin and also more sensitive to traces of oxygen

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18
Q

What color colonies does prevotella form when grown on blood agar plates?

A

black pigment

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19
Q

How would you distinguish fusobacterium morphologically?

A

needle shaped and very thin rods

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20
Q

What is fusobacterium sensitive to?

A

penicillin and trace oxygen

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21
Q

What are the nonspore forming anaerobic gram positive rods?

A 
Bifidobacterium
Corynebacterium
Lactobacillus
actinomyces
Clostridia
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22
Q

What does bifidobacterium look like on a gram stain?

A

Gram + rods with a tendency to branch with pleomorphic structure. Found in the colon. Not pathogenic.

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23
Q

What infection does corynebacterium cause?

A

Usually just contaminates blood samples as a normal inhabitant of the skin.

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24
Q

What morphology does corynebacterium take on?

A

Pleomorphic gram positive rods

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25
Where do you normally find lactobacillus? What is its relevance clinically?
Found in intestine and vagina. Non pathogenic, important in maintaining low pH to prevent growth of pathogens
26
Where do you normally find actinomyces?
oral pharynx and GI tract
27
What is the morphology of actinomyces?
gram positive branching rods
28
Where does actinomyces cause infection?
oral/dental/abdominal infections with sinus tract
29
What are the diagnostic features of actinomyces?
sulfur granules "molar tooth" appearance branching rods
30
What is an anaerobic gram positive cocci?
peptostreptococcus
31
What does peptostreptococcus infect?
pulmonary infections brian abscesses OB-GYN
32
What is an anaerobic gram negative cocci? What is its importance?
veillonella. Not an important pathogen
33
would you ever submit oral or fecal cultures for anaerobes?
No
34
What kind of media would you use for culturing anaerobic bacteria?
thioglycollate broth
35
How would you treat an anaerobic infection?
``` Penicillin (except below the diaphragm) Clindamycin 3rd generation cephalosporins Chloramphenicol Metronidazole Surgical drainage for abscess Metronidazole ```
36
What vitamins do the normal intestinal flora produce?
Vitamin B12 and Vitamin K
37
What is a problem with bacterial overgrowth in the small bowel?
fat malabsorption and vitamin B12 deficiency
38
What are the normal aerobes of the mouth flora?
``` viridans streptococci Neisseria species Diphtheroids S. epidermidis Eikenella corrodens ```
39
What is the morphology of viridans strep?
gram positive cocci, sometimes in chains
40
What is the predominant normal microorganism found in the mouth?
Viridans strep
41
What pathology can V strep cause?
bacterial endocarditis, dental plaque
42
What is the morphology of diptherioids?
pleomorphic gram positive rods.
43
What is the significance of diptheroids?
Most common contaminant of blood culture. Rare infection causing endocarditis
44
What is the morphology of S epidermidis?
gram positive cocci, round, and grape like clusters
45
What pathology can S epidermidis cause?
Common contaminant of blood cultures. Can infect catheters, intravascular devices
46
Upon hospitalization, patients may have their normal oral flora replaced with:
gram negative rods like E coli or klebsiella
47
What pathology does Eikenella corrodens cause?
human bites and clenched fist injuries
48
What are common oral anaerobes?
``` fusobacterium prevotella anaerobic streptococci actinomyces anaerobic spirochetes ```
49
Which oral anaerobes are penicillin sensitive?
fusobacterium prevotella anaerobic streptococci
50
Where would you stop finding oral flora?
lower trachea in healthy individuals
51
How would you treat an infection above the diaphragm?
With penicillin
52
When would you have stomach flora?
In cases of gastric achlorhydria or gastric obstruction
53
What bacteria would you find in upper small intestine?
Usuallly pretty sterile. | May find some gram positive aerobes. Sterile because of rapid movement and also unconjugated bile acids
54
What species do you find in terminal ileum?
E coli, enterobacter, gram negative organism. Anaerobes such as B fragilis predominate
55
What species do you find in the large intestine?
Mostly anaerobes
56
How is ammonia formed in the colon?
splitting urea
57
What do you use to treat infections below the diaphragm for anaerobic apecies?
clindamycin, cefoxitin, metronidazole
58
What are the predominant aerobic flora in the gut?
Coliforms (enteric gram negative rods) and enterococcus
59
What happens to bile with abnormal bacterial growth in the small intestine?
More conversion of conjugated bile acid to free bile acid, causing fat malabsorption
60
What is the major source of ammonia in the blood?
Bacterial degradation biproduct
61
What does intestinal bacteria do to bile pigments?
Converts bilirubin to stercobilin
62
What is the predominant organism of the skin?
Staphylococcus epidermidis
63
What other pathogens are found in the skin?
S aureus Diphtheroids proprionibacterium and peptococcus
64
What are the species in the upper respiratory tract?
S aureus viridans strep Neisseria Anaerobes: bacteroides, fusobacterium, clostridium, peptostreptococcus
65
What is the normal flora of the Gu tract?
lactobacillus in women E coli and enterobacter, which can cause UTI Group B streptococci. Can cause newborn sepsis
66
How would you tell the difference between B fragilis and Clostridium?
Clostridium is a spore forming obligate aerobe. In contrast, B. Fragilis does not form spores
67
What do anaerobes use as electron acceptors?
nitrogen or other inorganics
68
What enzyme do anaerobes lack?
Some lack superoxide dismutase and all lack catalase
69
Where would you find regions of low redox potential and therefore anaerobic infections?
Oral cavities, ileum and colon, female genital tract
70
What organisms would you suspect in gingivitis?
``` fusobacterium prevotella peptostreptococcus viridans strep (aerobe) actinomyces ```
71
What gram negative rod would you see in a human bite infection?
eikenella corrodens
72
What organisms would you suspect in upper respiratory infections spreading to the brain?
ACTINOMYCES | but also prevotella, fusobacterium, peptostreptococcus, strep viridans
73
What kind of infection would you expect with actinomyces?
An oral, pulmonary, or abdominal abscess or sinus tract infection

Quiz 3 Microbiology (4 decks)

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