Exam 4 (Anaerobes) Flashcards by Tabatha O'Keefe

Anaerobes usually fail to grow in the presence of _____, thus carry out _____:

oxygen

fermentation

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Some anaerobes are aerotolerant, such as:

Clostridium spp.

Actinomyces spp.

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Anaerobic organisms lack these two enzymes required to break down reactive oxygen species during aerobic metabolism:

superoxide dismutase

catalase

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Obligate aerobes grow well in __% O2:

21% O2

ambient room air

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____ are the most abundant bacteria in the human GI tract:

Anaerobes

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What would have more bacteria, the duodenum or the colon?

Colon. The number of bacteria increase as you move distally.

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What is the most abundant bacteria (normal flora) in the human colon?

Bacterioides spp.

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Anaerobes are the most abundant bacteria in the human_____, while Bacterioides spp. are the most abundant bacteria in the human ___:

GI tract

colon

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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

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Are Clostridial spp. also part of the normal flora, GI, and skin:

Yes.

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Microaerophilic Gram+ Catalase- thin rods with spiral forms that are normal flora of the female GU tract:

Lactobacillus spp.

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Rusty nails and skin punctures can lead to this type of disease transmission of anaerobes:

exogenous

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Are anaerobes commonly isolated from urine:

no. only 1% are anaerobes

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List some disadvantages to swab use for specimen collection:

drying
normal flora contamination
toxic exposure to air

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An example of a potentially acceptable swab specimen would be from where:

the uterus

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Blood specimens for culture should always be collected in what type of bottle(s):

both aerobic and anaerobic

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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

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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

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What is the preferred transport media for an anaerobic aspirate sample:

O2 free transport tube or vial containing PRAS media

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Infections with anaerobes tend to be ___:

polymicrobic

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Staph, Strep, and the Enterobacteriaceae family are _____ anaerobes:

Facultative

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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

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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

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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

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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:

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?

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