Anaerobes Flashcards
(96 cards)
1
Q
require atmosphere of 15-21% oxygen as found in air or CO2 incubator
i.e., Mycobacteria
A
Obligate aerobe
2
Q
require oxygen content lower than ambient air (<5%)
i.e., Campylobacter, Neisseria, Helicobacter
A
Microaerophilic
3
Q
organisms that multiply equally in the presence or absence of air
i.e., Enterobacteriaceae
A
Facultative anaerobe
4
Q
require increased CO2 (5-10%)
i.e., Haemophilus, Neisseria
A
Capnophile
5
Q
can survive some oxygen exposure, but will not be able to preform metabolic processes unless in an anaerobic environment
i.e., Bacteroides
A
Aerotolerant anaerobe
6
Q
requires strict anaerobic environment and are killed almost immediately in the presence of oxygen
i.e., Clostridium
A
Obligate anaerobe
7
Q
Exogenous anaerobes
A
- exist outside of the body
- infection develops at site of entry
- i.e., Clostridium, Fusobacterium
8
Q
Endogenous anaerobes
A
- exist inside the body
- source of infection in/throughout body
- usually polymicrobial infections
- i.e., Bacteroides, Peptostreptococcus, Actinomyces
9
Q
Skin anaerobes
A
Propionibacterium, Peptostreptococcus
10
Q
Respiratory tract anaerobes
A
Prevotella, Porphyromonas, Fusobacterium
11
Q
Gastrointestinal tract anaerobes
A
Bacteroides, Bifidobacterium, Clostridium, Eubacterium
12
Q
Genitourinary tract anaerobes
A
Fusobacterium, Prevotella, Bacteroides, Lactobacillus
13
Q
Predisposition to Anaerobic infections
A
- trauma to protective barriers (bowel, genital tract)
- vascular stasis (no oxygen to site)
- bite wounds, oral surgery, oral flora into deep lungs, burns with soil contamination
14
Q
Anaerobic bacteria (characteristics)
A
- close proximity to mucosal surface
- produces a foul odor
- large quantity of gas
- black color or brick-red fluorescence
- distinct morphological characteristics (pleomorphic, fusiform)
15
Q
Gram-positive, spore-forming, anaerobic, bacilli
A
Clostridium
16
Q
- boxcar-shaped gram-positive bacilli
- double zone of hemolysis on Brucella blood agar or blood agar
- lecithinase +
A
C. perfringens
17
Q
- heavily swarming
- terminal spores
A
C. tetani
18
Q
- heavily swarming
- subterminal spores
A
C. septicum
19
Q
Clostridium Clinical Infections
A
- mostly exogenous (wounds, ingest toxin)
- endogenous is C. difficile
- tetanus, gas gangrene, botulism, food poisoning
20
Q
C. perfringens food poisoning
A
- 3rd most common after Salmonella and Shigella
- Type A and Type C
21
Q
C. perfringens Type A food poisoning
A
- ingestion of enterotoxin
- causes diarrhea and cramps
- usually self-resolving
22
Q
C. perfringens Type C food poisoning
A
- causes Enteritis necroticans
- acute onset of severe abdominal pain and bloody diarrhea, vomiting
- necrotic inflammation of small intestines
- fatal without treatment
23
Q
- causes Botulism
- Botulism toxins A-G
- Toxins A, B, E associated with human disease
- causes flaccid paralysis
- caused by ingestion of toxin, ingestion of spores (infants), or wound botulism
- 2 hours to 8 days
A
C. botulinum
24
Q
infant botulism
A
- ingestion of spores in contaminated honey
- colonize colon and produce toxins
25
Tetanus
- caused by C. tetani
- tetanospasmin neurotoxin (inhibits neurotransmitters)
- symptoms begin after 7 days (long incubation)
- muscular rigidity of jaw, neck and lumbar
- vaccine available (DPT)
26
Myonecrosis (gas gangrene)
- most commonly caused by C. perfringens
- contaminated wounds from trauma or surgery
- alpha toxin causes tissue necrosis and deeper invasion
- tissue death that leads to amputation
- treat with antibiotics, surgical debridement and hyperbaric oxygen (to kill anaerobes)
27
Bacteremia
- C. perfringens is most common
- C. septicum is marker for GI malignancy
- C. bifermentans and C. tertium are secondary
28
Antibiotic-associated diarrhea
- C. difficile
- causes pseudomembranous colitis (bloody diarrhea, necrosis)
- antibiotics destroy flora, but not Clostridium so increased toxin production (Toxin A and B)
- nosocomial infection
- test for toxin, not culture
29
Gram-positive non-spore-forming anaerobic bacilli
- Actinomyces, Bifidobacterium and Propionibacterium
- Mobiluncus
- Lactobacillus
30
Actinomyces, Bifidobacterium and Propionibacterium
- cause Actinomycosis (sulfur granules)
- P. acnes is frequent blood culture contaminant
- normal skin flora
31
Actinomycosis
chronic granulomatous disease characterized by sinus tracts and fistulae that erupt to the surface and drain pus that contains "sulfur granules"
32
- bacterial vaginosis
| - overgrowth when Lactobacillus decreases
Mobiluncus
33
- highly pleomorphic bacilli
- contaminant
- bacteremia and endocarditis in ICP
Lactobacillus
34
Anaerobic gram-negative bacilli
- Bacteroides fragilis
- Prevotella
- Porphyromonas
- Fusobacterium
35
- #1 normal flora in colon
- most commonly isolated anaerobe from blood cultures
- #1 agent in peritonitis and intra-abdominal abscess
- grows on KVLB and BBE
- resistant to vanco, kanamycin and colistin disks
Bacteroides fragilis
36
- P. melaninogneica is #1 normal flora of gingiva
- also found in vagina
- peridontal disease, sinusitis, pneumonia, brain abscesses
Prevotella
37
- slow grower
- normal flora of oropharynx and urogenital tract
- head and neck infections
Porphyromonas
38
- commensal bacteria in gingiva
- normal in GI, GU and URT
- mixed infections (abscesses, peritoneal infections, diabetic foot ulcers)
- Lemierre disease (F. necrophorum)
Fusobacterium (necrophorum and nucleatum)
39
- long, thin rods with pointed ends
- breadcrumb, speckled or smooth colonies
- greening of agar with air exposure
- fluoresces chartreuse
- nonhemolytic, indole +, lipase -
F. nucleatum
40
- slightly pleomorophic with rounded ends
- circulate colonies
- greening with air exposure
- beta-hemolytic, indole +, lipase +
- fluoresces chartreuse
F. necrophorum
41
Anaerobic cocci
- Peptostreptococcus, Anaerococcus, Finegoldia, Parvimonas, Peptoniphilus (gram-positive)
- Veillonella (gram-negative)
42
Anaerobic cocci clinical infections
- brain abscesses, meningitis, aspiration pneumonia, lung abscess, gingivitis
- polymicrobial infections
43
Specimen collection
- acceptable specimens must be collected
- tissue biopsy or needle aspiration is best
- must be actual site of infection (not surface)
- rapid processing (because of oxygen toxicity)
44
Aspirates
- needle and syringe
- inject specimen into prereduced anaerobically sterilized media (PRAS)
- vortex and plate to isolation media
45
Anaerobic infections
MOST ARE POLYMICROBIAL
46
Swabs
not recommended for specimen collection
47
Blood
must collect anaerobic and aerobic blood culture bottles
48
Anaerobic chambers
- glove boxes, anaerobic jars, biobags
| - oxygen-free environment
49
Direct examination of anaerobic specimen
- rules in or out pathogens
- establishes polymicrobial or monomicrobial
- presumptive identification
- aids in selection of culture media
- determines specimen quality
50
Gram-staining anaerobes
use methanol instead of heat as a fixative
51
Anaerobic chambers
- 5-10% Hydrogen gas
- 5-10% CO2 gas
- 80-90% Nitrogen gas
- Palladium-coated alumina pellets to remove all oxygen
- desiccant to absorb excess water
- indicator (turns when O2 present)
52
Anaerobic cultures
- foul odor
- characteristic morphology on anaerobic agars
- unique morphology on gram stain
- good growth on Bacteroides bile-esculin agar (BBE)
- double zone of hemolysis
- brick-red fluorescence on KVLB
53
Kanamycin vancomycin laked blood (KVLB)
- anaerobes have brick-red fluorescence on agar
| - Porphyromonas and Prevotella turn it black
54
Processing suspected anaerobes
- Observe growth and morphology on selective media
- Observe gram-stain and cell morphology
- aerotolerance test
- inoculate pure culture plate and add disks
55
determines whether an organism is a strict anaerobe or a facultative anaerobe
Aerotolerance test
56
Aerotolerance test (plates)
- chocolate agar plate incubated in CO2 incubator
| - anaerobic blood agar plate incubated anaerobically
57
Brick-red fluorescent anaerobes
Prophyromonas and Prevotella
58
Chartreuse fluorescent anaerobes
Fusobacterium nucleatum, Fusobacterium necrophorum and Clostridium difficile
59
red fluorescent anaerobe
Veillonella
60
Catalase test
separates Bacillus (+) and Clostridium (-)
61
Anaerobe tests
catalase test
spot indole test
rapid urease test
rapid motility test
62
Spot indole test
- dilated cardiomyopathy with ataxia (DCMA) reagent
- blue/green is positive
- different from regular indole test
63
Anaerobe special potency disks
Vancomycin disk, Kanamycin disk, Colistin disk
64
Vancomycin disk
- gram-positive bacillus and Porphyromonas are susceptible
| - Fusobacterium are resistant
65
Kanamycin disk
- Bacteroides (not fragilis), Bilophila, Fusobacterium and Veillonella are susceptible
- Porphyromonas, B. fragilis are resistant
66
Colistin disk
- Bacteroides (not fragilis), Bilophila, Fusobacterium, Veillonella and Prevotella are susceptible
- Porphyromonas, B. fragilis are resistant
67
Anaerobic antimicrobial disks
Bacteroides fragilis is resistant to all 3 (Vanco, Kanamycin and Colistin)
68
Nitrate disk
organisms that have ability to reduce nitrate
69
Sodium polyanethol sulfonate (SPS) disk
- Peptostreptococcus anaerobius is susceptible
| - Peptoniphilus asaccharolyticus is resistant
70
Bile disk
- for organisms that can grow in 20% bile
| - B. fragilis
71
Egg Yolk Agar (EYA)
- Lecithinase cleaves lecithin found in egg yolk and releases insoluble fat
- forms opaque zone around colony
- C. perfringens (lecithinase +)
72
Lipase
- hydrolyzes triglycerides and diglycerides to fatty acids and glycerol
- iridescent, multicolored sheen
- F. necrophorum (+)
73
Clostridium (identification)
- double zone of hemolysis
- Cycloserine-cefoxitin-fructose agar (CCFA)
- lecithinase and lipase reactions
- spot indole, rapid urease, gelatin hydrolysis
74
- selective and differential for C. difficile
| - has yellow "ground glass" colonies
Cycloserine-cefoxitin-fructose agar (CCFA)
75
Bile-tolerant gram-negative bacilli
Bacteroides fragilis
76
Bile-sensitive pigmented gram-negative bacilli
Porphyromonas and Prevotella
77
Bile-sensitive nonpigmented gram-negative bacilli
Bacteroides ureolyticus, Campylobacter, Bilophila wadsworthia
78
B. fragilis (special media)
KVLB and BBE biplate
79
Pigmented Gram-negative bacilli
Bacteroides, Prevotella, Porphyromonas
80
- produces protoporphyrin
- brown-black color shift of macroscopic colonies over 2-3 weeks
- brick-red fluorescence
Prevotella
81
- brick-red fluorescence
| - no growth on media containing vancomycin
Porphyromonas
82
- isolated following tooth extraction
- nonpigmented
- pits the agar
- urease +
B. ureolyticus
83
Prevotella (body sites)
vagina and oral cavities
84
- gram-negative
- long, thin, tapered rods
- may be pleomorphic
Fusobacterium
85
- classic fusiform shape
- indole +, lipase -
- butyric acid from PYG media
F. nucleatum
86
Other Fusobacterium
F. mortiferum, F. russi
87
- many clinical specimens contain these
- vagina and abscesses
- tetrads, chains or clusters
- P. anaerobius, P. asaccharolyticus
Anaerobic gram-positive cocci
88
- gram-positive cocci
- SPS sensitive
- indole -
- acid production in PYG
Peptostreptococcus anaerobius
89
- gram-positive cocci
- SPS resistant
- indole +
Peptostreptococcus asaccharolyticus
90
Antimicrobial susceptibility testing is performed in
```
brain abscesses
endocarditis
prosthetic device infection
vascular graft infection
joint infections
osteomyelitis
bacteremia
```
91
Highly virulent/commonly resistant anaerobes
```
B. fragilis
Prevotella
Clostridium
Fusobacterium
B. wadsworthia
Sutterella wadsworthensis
```
92
Treatment of anaerobic diseases
- destroy reduced environment (debridement, draining)
- hyperbaric oxygen environment
- antimicrobials, antitoxins
93
Definitive ID tests
- biochemical systems
- gas-liquid chromatography
- ribosomal sequencing
94
Presumptive ID tests
- disks
- media
- morphology
95
- pitting of agar
| - urease +
Bacteroides ureolyticus
96
Actinomyces
- cause Actinomycosis (sulfur granules)
| - molar tooth colonies
