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D&T test 7- GI > Anaerobes, Bacteroides, others > Flashcards

Anaerobes, Bacteroides, others Flashcards

1
Q

Why do Anaerobe (except Clostridium) infections have facultative anaerobes too?

A

the facultatives use up the oxygen, then the strict anaerobes take over

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2
Q

do Anaerobes (except Clostridium) produce spores

A

no

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3
Q

Name the Clinically significant nonspore-forming Gram (-) rods anaerobes (4)

A

Gram (-) rods - Bacteroides, Prevotella, Porphyromonas, Fusobacterium

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4
Q

Name the Clinically significant nonspore-forming Gram (+) cocci anaerobes (1)

A

Gram (+) cocci – Peptostreptococcus

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5
Q

Name the Clinically significant nonspore-forming Gram (+) rods anaerobes (1)

A

Actinomyces

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6
Q

When do infections by Clinically significant nonspore-forming anaerobes occur? (4)

A

• Infections occur when:

  1. there has been a breach in integrity of body site,
  2. loss in immune function, or
  3. antibiotic-induced change in normal flora (overgrowth of certain anaerobes).
  4. Anaerobic bacteria can also travel from their normal site to enter a normally sterile site. (in blood)
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7
Q

Name 6 clinical manifestations of anaerobic infections

A 
• Abscesses (from normal flora-site)
	• Peritonitis, wound infx (after surgery)
	• Dental and oral infx (cervico-facial)
	• Necrotizing PNA
	• PID
Bite Wounds
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8
Q

Why does trauma increase risk of anarobic infx

A

the loss of blood supply –> anaerobic conditions

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9
Q

Infection by anaerobes commonly follows what 2 events?

A

Infection following human or animal bites or related to ABX use

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10
Q

actinomyces infx presents with what in discharges?

A

Presence of sulfur granules in discharges

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11
Q

What is seen on wounds to indicate anaerobic infx (3)

A
  1. Foul-smelling wound or dischrage

2. Tissue necrosis or 3. abscess formation near mucosal surface

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12
Q

What would the gram stain and culture of an aerobic infx look like

A

Organisms seen on Gram stain, but no growth on routine aerobic culture- “sterile pus”

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13
Q

What do the inappropriate specimens for culturing an anaerobe have in common

A

(all likely to contain normal anaerobic flora or are not anaerobic sites): throat swabs, gingival swabs, sputum, feces, gastric contents, urine, vaginal swabs

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14
Q

What are the Category 1 drugs for anaerobes (3)

A

Carbapenems- cover aerobes as well
Metronidazole
B-lactams with B-lactamase inhibitors (ampicillin/sulbactam, ticarcillin/clavulenic acid)

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15
Q

What are the 2 Category 2 drugs for anaerobes

A

Clindamycin, cefoxitin (ceph)

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16
Q

gram stain and shape of Bacteroides, Porphyromonas and Prevotella

A

gram-negative rods.

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17
Q

Porphyromonas -what species name and where found normally

A

P. gingivalis - normally oral

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18
Q

Prevotella -what species name and where found normally

A

P. melaninogenica - oral (and vagina)

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19
Q

What anaerobe is Tan to black pigmentation on blood agar; requires vitamin K, hemin?

A

P. melaninogenica

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20
Q

P. gingivalis is uniquely found in what infx

A

abscesses (gingiva)

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21
Q

P. melaninogenica is found in what infx (3)

A

bite wounds, lung abscesses, genital infections

22
Q

What is the Most commonly isolated anaerobe from opportunistic infections

A

B. fragilis

23
Q

What does P. melaninogenica look like on blood agar? What does it require to grow? (2)

A

Tan to black pigmentation on blood agar; requires vitamin K, hemin

24
Q

What is B. fragilis oxygen requirement? Why?

A 
Moderate anaerobes (can tolerate a higher redox potential than some anaerobes bc it contains:
SOD- resists oxygen toxicity
25
Q

What is the major virulence factor for invasive disease from B. fragilis?

A

Polysaccharide capsule –

26
Q

Does B. fragilis show bacteremia, toxemia, sepsis or some combo? and why?

A

bacteremia without sepsis bc the LPS- shows no endotoxin activity-
No texemia - bc there is no histotoxin produced!!!

27
Q

What populations does Enterotoxin-producing B. fragilis (ETBF) affect and how?

A

kids: 1-5 yo = diarrhea
Adults: IBD

28
Q

What is the virulence factor produced by ETBF?

A

Zinc metalloprotease called fragilysin

29
Q

4 infx/disease processes caused by B. fragilis

A

i. Abdominal abscesses, surgical infections such as peritonitis
ii. Pelvic inflammatory disease (PID) – (spread to vagina from intestines)
iii. Bacteremia without sepsis, with spread to lung, brain etc. (abscesses) – 25% mortality
iv. Diarrhea (ETBF)

30
Q

4 effective drugs for B. fragilis infx

A
  1. metronidazole – most commonly recommended
  2. carbapenems such as imipenem, ertapenum, doripenum, meropenum
    1. β-lactam/β-lactamase inhibitor
31
Q

How to prevent B. fragilis infx

A

Pre-surgery prophylactic ABX treatmen

32
Q

fusobacterum morphology and gram stain

A

gram-negative bacilli

long and thin with pointed ends (fusiform morphology)

33
Q

F. nucleatum and F. necrophorum are normally found where, respectively

A

F. nucleatum= oral

F. necrophorum= intestinal

34
Q

F. nucleatum and F. necrophorum cause what diseases, respectively?

A

F. nucleatum = Acute necrotizing ulcerative gingivitis (ANUG) (trench mouth)
F. necrophorum = liver and abdominal abscesses

35
Q

What is the gram stain and morphology of poststreptococcus?

A

the only anaerobic gram-positive cocci seen in human infections

36
Q

Tx for poststreptococcus

A

PCN

37
Q

Actinomyces gram stain, acid fast stain, morphology

A

Gram-positive filamentous branching bacilli; non acid-fast

38
Q

Nocardia: gram and acid fast stain

A

doesn’t gram stain

AFB

39
Q

Actinomyces oxygen requirements

A

grow best anaerobically, some are more aerotolerant

40
Q

Actinomyces normal where (3)

A

Normal flora- oral cavity, intestinal tract, vagina.

41
Q

classic finding in actinomyces CP

A

“sulfur” granules in pus

42
Q

3 disease processes caused by Actinomyces

A

Cervicofacial lesions
Abdominal lesions
Salpingitis (IUD-related)

43
Q

Eikenella corrodens: gram stain and oxygen requirements

A

G(-)

NOT AN ANEROBE - facultative anaerobe

44
Q

How is Eikenella corrodens transmitted and where is it normal

A

human bites- normal in oral

45
Q

potential serious CP of Eikenella corrodens

A

subacute endocarditis (HACEK bacteria)

46
Q

Tx for Eikenella corrodens

A

PCN-G

47
Q

What is MC bacteria found in dog/cat bites?

A

Pasteurella multocida

48
Q

Pasteurella multocida Gram stain and morphology. Also- special staining chc

A

gram-negative coccobacilli or rods.

Exhibit bipolar staining

49
Q

virulence factor for Pasteurella multocida

A

anti-phagocytic capsule.

50
Q

Clinical manifestations of Pasteurellosis (2)

A

Cellulitis = MC

Spread to blood (septicemia, meningitis)-

51
Q

Tx of Pasteurella multocida (3)

A

Penicillin G - anaerobe,

ampicillin, cefuroxime- aerobic

D&T test 7- GI (14 decks)

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