anaerobic bacteria

Question 1

Name the 6 types of oxygen requirement groups

Answer 1

1. Aerobes- require oxygen (Bacillus)
2. Microaerophiles - require low oxygen levels (Campylobacter)
3. Facultative anaerobes -can grow with or with O2
   (Enterobacterales, Staph)
4. Aerotolerant anaerobes - prefer anaerobic conditions but can grow in O2 (Lactobacillus, Cutibacterium, some Clostridium sp)
5. Obligate anaerobes - only grow in absence of oxygen (Clostridium perfringes, Bacteriodes fragilis group, Fusobacterium)
6. Capnophiles - require elevated CO2 (Neisseria)

Question 2

Name the gram positive anaerobes (5 impt. ones)

Answer 2

1) Clostridium
2) Cutibacterium
3) Proprionibactereium
4) ACTINOMYCES
5) Lactobacillus

Peptostreptococcus
Bifidobacterium
Eubacterium

Question 3

Name the gram negative anaerobes (3 important ones)
and 2 commensals

Answer 3

1) Bacteroides
2) Fusobacterium
3) Prevotella

4) Porphyromonas
5) Veilonella (only gram negative anaerobic dipplococci)

Question 4

Name the GI anaerobes (3 important)

Answer 4

1) Bacteroides
2) Clostridium
3) Lactobacillus

Bifidobacterium
Eubacterium
Peptostreptococcus
Veilonella
Actinomyces

Question 5

Name the ORAL anaerobes (2 important)

Answer 5

1) Prevotella
2) Fusobacterium

Actinomyces
Porphyromonas
Peptostreptococcus
Veilonella

Question 6

Name the SKIN anaerobes (3 important ones)

Answer 6

1) Cutibacterium
2) Propionibacterium
3) Actinomyces

Question 7

Which anaerobes are associated with skin and soft tissue infections (2)?

Answer 7

1) Bacteroides fragilis group
2) Clostridium

Question 8

Which anaerobes cause intra-abdominal infections?

Answer 8

1) Bacteroides fragilis group
2) Clostridium

Question 9

Which anaerobes cause joint infections?

Answer 9

Cutibacterium acnes

Question 10

Acceptable specimens for anaerobic culture

Answer 10

Only specimens that were collected from sterile body sites

Abscesses/aspirates drained by needle​

Pleural fluid/empyema​ (fluid that accumulates around the lungs)

Surgically collected tissue​

Bile​

Peritoneal or thoracentesis fluid​

Sterile body fluid (CSF, joint, etc.)​

BAL (if collected with anaerobic brush)​

Question 11

Name anaerobic agar media (6)

Answer 11

1) Brucella (nonselective)

2) CDC anaerobic blood agar (non selective)

3) Brucella (with lysed blood agar with Kan and Vanc)

4) BBE agar (esculin is hydrolyzed by bacteriodes = black)

5) Anaerobic PEA (inhibits gram negatives and swarmers)

6) Egg yolk plate (Allows determination of lecithinase and lipase activity)

Question 12

Name anaerobic liquid media

Answer 12

1) Chopped meat broth with glucose (non selective)

2) Thio broth (non selective, but can differentiate based on oxygen tolerance)

Question 13

Bacteroides fragilis cause which diseases?

Answer 13

1) Intra-abdominal infection​ (often after ruptured appendix)​

2) Skin and soft tissue infection​

3) Bacteremia​

typically isolated in the lab and forms black colonies on BBE

Question 14

Intrinsic resistance of bacteroides fragilis group?

Answer 14

Almost all beta lactamase positive

Susceptible to beta lactam + lactamase inhibitors and carbapenems

2nd gen cephalosporins might also work

Question 15

Culture characteristics of Fusobacterium species

Answer 15

Obligate anaerobe

Gram negative rod

Long and thin, needle-like

Do not grow on BBE

Question 16

Fusobacterium necrophorum causes what?

Answer 16

Lemierre’s syndrome

starts with an oralpharyngeal primary infection (tonsilitis, pharyngitis, abscess. The bacterial endotoxin induces platelet aggregation and septic thrombus formation. The septic emboli lodge in the lungs, liver, endocardium, or joints.

key symptoms: swollen cervical lymph nodes, and a swollen, tender or painful neck

High mortality without treatment

Treatment: surgery + beta lactase and metronidazole

Question 17

Name the 2 common Fusobacterium spp isolated in the clinical lab

Answer 17

Fusobacterium necrophorum

Fusobacterium nucleatum

Both are normal flora of the oral and respiratory tract

Question 18

What infections do Prevotella and Porphymonas cause?

Answer 18

Periodontal infections (polymicrobial) and dental abscesses
Rare cause of systemic disease

Associated with poor oral hygiene

Question 19

Are Clostridium strict anaerobes?

Answer 19

May (slowly) grow aerobically as well as anaerobically​

Question 20

What are some characteristics of Clostridium species in gram stains?

Answer 20

1) spores are not always seen, only in stressed conditions
2) overdecolorize easily and may appear Gram negative
3) the spores are generally bulging from the spore (terminal)

Bacillus spores are usually in the center

Question 21

Name the 4 Clostridium pathogens

Answer 21

C. tetani - tetanus
C. botulinum - wound botulism
C. perfringens - gangrene (black dead tissue due to lack of oxygen)
C. septicum - colon cancer (like S. bovis)

Question 22

Diseases associated with Clostridium septicum ?

Answer 22

Presence of this organism (including sepsis) is linked to colon cancer and hematologic abnormalities including leukemia​ (S. bovis does too)

High mortality rate

Question 23

Diseases associated with Clostridium perfringes?

Answer 23

1) Food poisoning (due to toxin contamination in heated food (soup, sauces))

2 ) Most commonly associated with gas gangrene - black necrotic tissue due to lack of oxygen

3) Acute intravascular hemolysis is a rare and often lethal complication of Clostridium perfringens septicemia

4) other skin and soft tissue infections (cellulitis and fasciitis)

Question 24

What disease is Clostridium botulinum associated with?

Answer 24

Botulism

Toxin ingestion

Muscle relaxation (flaccid paralysis)
Causes facial weakness, issues swallowing speaking, breathing, can lead to paralysis

Question 25

How is Clostridium botulinum acquired?

Answer 25

it is found in soil and water
The toxin may be ingested from food, wounds (cuts, needle sticks), and may be found in honey (toxic to <1yr babies)

Most potent neurotoxin

Question 26

How is botulism diagnosed?

Answer 26

Detection of botulism toxin in clinical specimens (stool)

ELISA, or Lateral flow tests

Question 27

Which disease is associated with Clostridium tetani?

Answer 27

Tetanus

Rusty nails

Disease is mediated by toxin production

The toxin causes muscle spams (tight arch back, clenching fists)

Question 28

DTaP

Answer 28

Vaccine against
Diphtheria, tetanus, and pertussis

Babies and children younger than 7 years old receive DTaP

Question 29

TDaP

Answer 29

Vaccine against Tetanus, diphtheria, and pertussis

7 year olds and above

Question 30

What does a gram stain with Cutibacterium acnes look like?

Answer 30

Spiderlike branching
Gram positive anaerobe (but may slowly grow aerobically)

*often a skin contaminant, skin commensal

Question 31

What mild infection does Cutibacterium acnes cause and what is the treatment?

Answer 31

Skin infections in blocked pores or hair follicles
It likes sebaceous glands

Topically with clindamycin or tetracycline
(can be administered systemically)

Question 32

What is a severe infection with Cutibacterium acnes and how is it treated?

Answer 32

joint infections, especially prosthetic joints

Prefers to colonize upper body regions

Treated with penicillin or ceftriaxone, susceptibility tests not req.

Question 33

What diseases are associated with Actinomyces israelii?

Answer 33

Head and neck abscesses
Pelvic infections associated with IUDs

Question 34

What are some culture characteristics of Actinomyces israelii?

Answer 34

Branch Gram positive rods
Modified acid-fast negative
Looks like a molar tooth
Anaerobe

Bacterial Aggregates on wounds look like Sulfur granules when drained