Exam 4 (Anaerobes) Flashcards
Anaerobes usually fail to grow in the presence of _____, thus carry out _____:
oxygen
fermentation
Some anaerobes are aerotolerant, such as:
Clostridium spp.
Actinomyces spp.
Anaerobic organisms lack these two enzymes required to break down reactive oxygen species during aerobic metabolism:
superoxide dismutase
catalase
Obligate aerobes grow well in __% O2:
21% O2
ambient room air
____ are the most abundant bacteria in the human GI tract:
Anaerobes
What would have more bacteria, the duodenum or the colon?
Colon. The number of bacteria increase as you move distally.
What is the most abundant bacteria (normal flora) in the human colon?
Bacterioides spp.
Anaerobes are the most abundant bacteria in the human_____, while Bacterioides spp. are the most abundant bacteria in the human ___:
GI tract
colon
What is the job of normal flora in the GI tract:
Breakdown food products into forms our bodies can absorb.
*Also break down dietary carcinogens
Are Clostridial spp. also part of the normal flora, GI, and skin:
Yes.
Microaerophilic Gram+ Catalase- thin rods with spiral forms that are normal flora of the female GU tract:
Lactobacillus spp.
Rusty nails and skin punctures can lead to this type of disease transmission of anaerobes:
exogenous
Are anaerobes commonly isolated from urine:
no. only 1% are anaerobes
List some disadvantages to swab use for specimen collection:
- drying
- normal flora contamination
- toxic exposure to air
An example of a potentially acceptable swab specimen would be from where:
the uterus
Blood specimens for culture should always be collected in what type of bottle(s):
both aerobic and anaerobic
What sample preparation should take place when collecting specimen for blood culture:
- First sanitize skin with iodine or clorhexidine gluconate
* Follow with 70% isopropyl alcohol
T/F
Once an aspirate sample is in the syringe, extra should be expelled, then aspirate should be injected into an O2 free transport tube or vial containing PRAS media:
True
What is the preferred transport media for an anaerobic aspirate sample:
O2 free transport tube or vial containing PRAS media
Infections with anaerobes tend to be ___:
polymicrobic
Staph, Strep, and the Enterobacteriaceae family are _____ anaerobes:
Facultative
Anaerobes causing infection often come from what types of areas in the body:
warm, moist areas (i.e. GI tract)
*it is important to create artificial transport conditions to mimic this to avoid shocking the bacteria
What are the two ways to achieve an anaerobic environment with a heavy plastic air tight jar:
1) Evacuation-Replacement (vacuum removes air, replaced with N/CO2/H)
2) Add a GasPak
How will you know an anaerobe jar has achieved proper conditions with a GasPak:
Heat will be produced and condensation will collect on walls of jar ~ takes 30 mins
*also contains methylene blue indicator (turns blue to white) when conditions achieved
What allows for an anaerobic environment for the entire work-up of the specimen from inoculation on:
Anaerobe chamber aka Glove Box
PEA agar stands for:
Phenylethyl alcohol
KVLB agar stands for:
Kanamycin-vancomycin laked blood
KVB stands for:
Kanamycin-vancomycin blood
BBE stands for:
Bacteroides bile-esculin
Because anaerobic infections are typically polymicrobic, what else should specimen be plated on:
Aerobic SBAP
CAP
MAC
All primary isolation media for anaerobes should be supplemented with these 3 things:
hemin
blood
Vitamin K
What is the gold standard for definitive ID of anaerobes:
Gas chromatography (analyzes metabolic end products)
What does PRAS stand for:
Pre-Reduced Anaerobically Sterilized
This media is produced under oxygen free conditions, contains reducing agents, and is shipped in sealed foiled packages to maintain O2 free environment:
PRAS
Reduction of PRAS involves the use of ___ to removed any dissolved ___ in the media itself:
chemicals
O2
Anaerobic BAP is a non-selective supplemented with these 4 things:
yeast
hemin
Vitamin K
Cystine
Anaerobic PEA inhibits these, but allows for this:
- inhibits: Proteus swarming, Enterobacteriaceae
* allows: Gram+ growth
KVLB is selective for _________,
Vancomycin inhibits ______, while Kanamycin inhibits ____:
- Gram- obligate anaerobes (Prevotella, Bacteroides)
- V inhibits all Gram+
- K inhibits Gram- facultative anaerobic bacilli
Laked blood medias refers to the:
freezing and thawing of blood
This process has been shown to improve pigment production by Prevotella melaninogenica:
The process of freezing and thawing - in the making of laked blood medias
BBE agar provides presumptive ID of what:
Bacteroides fragilis
____ agar detects organisms that can grow in 20% bile and hydrolyze esculin:
BBE agar
BBE also contains what antibiotic, and why:
gentamicin
inhibits facultative anaerobes and most Gram- organisms
What do you look for on BBE agar:
growth and brown-black colonies/ blackening of medias
KVLB agar is selective for ________, and inhibits growth of______:
Gram- obligate anaerobes
All Gram+ organisms
KVLB is specifically selective for these two organisms:
- Prevotella
* Bacteroides spp.
Laked blood medias refers to the :
freezing and thawing blood (this process has been shown to improve pigment production of Prevotella melaninogenica)
Growth on this agar provides presumptive ID for Bacteroides fragilis:
BBE
look for growth of brown-black colonies/blackening of the media
T/F
BBE contains Gentamicin
True.
Gentamicin inhibits facultative anaerobes and most Gram- anaerobic organisms
This has a small amount of agar added to it which prevents the widespread diffusion of oxygen, allowing anaerobes to grow:
Thioglycollate broth
This supplements plating media, supports growth of most anaerobes in clinical specimens, and provides back up for slow growing anaerobes or failing anaerobic system:
Thioglycollate broth
Why would you not treat any non-wound infection with C. botulinum with antibiotics:
Antibiotics may hasten the release of toxin
List the 3 species of Bacteroides:
B. fragilis
B. thetaiotaomicron
B. ovatus
This is the most abundant bacteria in the human colon, typically cause infections below the diaphragm, and have virulence factors:
Bacteroides spp.
Once Botulism neurotoxin enters body, then bloodstream and lymphatics, it makes its way to ____ blocking ____ release, and creating symptoms:
Neuromuscular junctions
neurotransmitter release
Bacteriodes is _____ to penicillin, kanamycin, vancomycin, and typically colistin:
resistant
Bacteroides is susceptible to:
Rifampin
_____ is a Gram- asaccharolytic rod that has bright red fluorescence under UV light:
Porphyromonas
T/F
Porphyromonas more commonly causes infections of head regions, and is normal flora of oral cavity:
True
Are all Prevotella melaninogenica strains pigmented:
No. Some are non-pigmented.
Prevotella melaninogenica provides a presumptive ID via:
brick red fluorescence under UV light
How do you distinguish Prevotella melaninogenica from Porphyromonas:
P. melaninogenica is saccharolytic
Gram- slight curved rods that are normal flora of the oral cavity and infections typically occur above the thorax:
Fusobacterium
Clostridium spp. is Gram___, catalase___, and does/does not form endospores:
Gram+
Catalase-
Spore forming
T/F
Clostridium spp. are obligate anaerobes, sometimes aerotolerant.
True
_____ has subterminal spores and resemble a tennis racket:
Clostridium botulinum
C. botulinum consists of ____ distinct groups. Groups _____ cause human botulism, group___ causes animal botulism, and group ____ typically is not associated with any disease:
4 distinct groups
I and II– human botulism
III– animal botulism
IV–no disease
Groups I and II of C. botulinum cause ___:
human botulism
____ has a neurotoxin that causes flaccid paralysis:
C. botulinum
Of the 7 types of toxins produced by C. botulinum (A-G), which ones cause human disease:
A
B
E
F
What are the 4 forms of botulism:
Foodborne (canned foods)
Infant (honey)
Wound (rare)
Inhalation (terrorism)
Does Botulism neurotoxin enter body through GI tract, mucous membranes, eyes, or respiratory tract:
All of the above.
Once Botulism neurotoxin enters body, then bloodstream and lymphatics, it makes its way to ____ blocking ____ release, and creating symptoms:
Neuromuscular junctions
neurottransmitter release
Foodborne botulism can begin in __hour, typically within __hours after ingestion of pre-formed neurotoxin:
6 hours
18-36 hours
Recovery of foodborne botulism can take __to___ until affected nerve endings grow, mortality rate is __%:
months to years
3-5%
How long must home canned goods be boiled to inactivate botulism toxin:
10 mins
Specimens for foodborne botulism can include the following:
serum
gastric contents
feces
suspected food
Describe the mouse bioassay for botulinum toxin:
- Mouse injected with pt serum
* Presence of symptoms in mouse confirm toxins presence
With infant botulism, neurotoxin production occurs ____:
in vivo
What is the tx for infant botulism:
high quality supportive care
not antibiotics
____ spores are oval with terminal or subterminal location, creating a drumstick or tennis racket appearance on Gram stain
Clostridium tetani
Actinomyces israelii is fungus-like, anaerobic, normal flora of ____, Gram__ rod:
mouth, gums, teeth
Gram+
There are ___ cases of C. tetani in the U.S. every year:
29
What is the toxin in C. tetani called and what does it do:
Tetanospasmin toxin
*disrupts nerve impulses to muscles
List the 3 cocci anaerobes in this unit:
Peptostreptococcus anaerobius
Peptococcus niger
Veillonella parvula
Where is C. tetani found:
ubiquitous (rusty metal, soil)
Is C. tetani included on the Vitek 2 ANC?
No
Clostridium perfingens produces up to __ toxins and causes the following infections:
12 toxins
- Cellulitis
- Myonecrosis (gas gangrene)
- Food poisoning
- Enteritis necroticans
Double zone of hemolysis is associated with this organism:
inner beta hemolysis, outer ring of alpha
Clostridium perfringens
In the double zone of hemolysis, the alpha hemolysis is due to:
alpha toxin
lecithinase activity
C. perfringens strains producing ____ are the third most common cause of bacterial food poisoning in U.S.:
C. perfringens enterotoxin (CPE)
Can humans be carriers of C. perfringens:
potentially
What has to be done for confirmatory ID of C. perfringens induced food poisoning:
feces need to be sent to public health lab at 4 degrees C
*Reverse CAMP test (is +)
Describe the reverse CAMP test:
C. perfringens and S. agalactiae have syngergistic interaction (*bowtie)
Is Clostridium difficile normal flora in some people:
Yes, in a small number of people.
List the exotoxins produced by C. difficile:
- Toxin A: Enterotoxin
* Toxin B: Cytotoxin
Stool cultures for C. diff should be ___, not ____, to distinguish infection from colonization:
watery, not formed
What does CCFA stand for and which organism is it used for:
Cycloserine-cefotoxitin fructose agar
*C. diff
_____ is an egg yolk based agar selective for C. diff by creating yellow glass ground colonies:
CCFA
List the treatment for C. diff infection:
- d/c initial antibiotic tx
* vanco for severe disease, possible surgical intervention
T/F
There is an enzyme immunonoassays for C. diff toxins A and B:
True
This organism appears filamentous (hyphal strands) in pus or tissue, and has a molar tooth appearance on agar:
Actinomyces isrealii
This is a chronic infection with local abscesses with formation of oozing sinus tracts containing sulfur granules, and is caused by this organism:
Actinomycosis (Actinomycotic mycetoma)
*Actinomyces israelii
Peptostreptococcus anaerobius is a Gram__, coccobacillus, often in ___, and causes these ailments:
Gram+
chains
endocarditis, GU/GI infection,
periodontal disease, gingivitis
T/F
The 3 cocci anaerobes in this unit are normal flora?
True
This Gram+ cocci in pairs/tetrads, produces tiny black, convex, smooth colonies on anaerobic BAP which turn light gray if exposed to air:
Peptococcus niger
T/F
Peptococcus niger is often associated with human disease:
False!
This Gram- diplococci in pairs/clusters/short chains produces a red fluorescence under UV light and has been found to create a biofilm along with Strep mutans:
Veillonella parvula
What do Veillonella parvula and Strep mutans form together:
a biofilm, that in combination imparts greater resistance to Strep mutans to various antimicrobials
____ is Gram- diplococci that is normal flora of human mouth and GI, and can cause infection in sinuses, lung, heart, bone, and CNS:
Veillonella parvula
