BACTE_FInals_Lec: Anaerobes (in progress)

why anaerobes are sensistive to aerobic condirons

Oxygen becomes Superoxide anion, which reacts with hydrogen perooxide to generate hydroxyl radical (OH-)

enzyme that protects strict aerobes and facultative anaerobes from superoxide anions

• exogenous

• endogenous (microbiota of humans and animals)

Anaerobes

found in mucosal surfaces

• linings of oral cavity

• GI Tract

• Genitourinary (GU) Tract

Anaerobes at specific anatomic sites

P. acnes

• an opportunistic pathogen that casues acnes

B. fragilis group, such as B. vulgatus, B. thetaiotaomicron, and B. distasonis

Common anaerobes in GI Tract

Bacteroides fragilis

most common species of anaerobic bacteria isolated from soft tissue infections and bacteremia

True

T/F

anaerobic bacteria colonize the distal urethra - not considered to be a cause of uncomplicated urinary tract infections

anaerobic cocci, Fusobacterium, Prevotella, Bacteroides, and Lactobacillus

Colonizers of GU Tract

Conditions that exposes individuals to anaerobe-associated infections or diseases

• Aspirates* and biopsy

best specimen collection for anaerobes

Anaerobic chamber

• provides the anaerobic environment

palladium-coated alumina pellets

These are catalysts that removes residual oxygen in the anaero. chamber

silica gel or alternative: solid-state dehumidifier

5% H2, 5-10% CO2, 85-90& Nitrogen

Anaerobic gas composition in the chamber

• Methylene Blue (colorless in anaerobic conditions)

• resazurin (

• digital oxygen indicators

note: chemicals do not react to small amounts of oxygen

Redox indicator in the chamber

GasPak jar

• Used by small laboratories

• Uses an envelope gas generator (waterless or requires water)

• Sodium borohydride (NaBH4) - reducing reagents

• NaHCO3 (sodium bicarbonate) - pH buffer

• Palladium pellets - catalyst for H & O2 rxn to form H2O

Components of GasPak

• prone to explosion when exposed to flammables due to accumulation of Hydrogen molecules in the GasPak

Disadvantage of GasPak

Anaerobic bags

• Ziplock bag

• Oxygen removal system (strips)

• Can be used in conjunction with jars

• Can be used for transport

Anaerobic blood agar (ex. CDC agar)

Preferred media for anaerobic culture

Bacteroides bile esculin agar

• selective medium for Bacteroides fragilis

• contains 20% bile which inhibits most anaerobes

• contains gentamicin (inhibits aerobes)

Phenylethyl alcohol agar

Media:

• this inhibits the swarming proteus spp.

• inhibits the growth of fac. anaerobes

C. perfrigens

Clostridium sp.

• has a double zone hemolysis (inner - beta, outer - alpha)

Clostridium

All spore-forming anaerobic bacilli are classified in the genus _____

C. perfringens

C. ramosum

C. innocuum

All Clostridium are motile except

C. perfringens

The only encapsulated Clostridium sp.

• C. tetani

• C. perfringens

• C. botulinum

Exogenous Clostrium spp. (3)

C. tetani

This bacteria causes tetanus

C. perfringens

This bacteria causes gas gangrene (myonecrosis) food posioning

C. botulinum

This bacteria causes botulism

C. difficile

this bacteria causes antibiotic-associated pseudomembranous colitis

Myonecrosis

• aka gas gangrene

• usually occurs when organisms contaminate wounds, through trauma or surgery

alpha-toxin (a-toxin)

found in C. perfringens that is a lecithinase (phospholipase C) produced by all strains of C. perfringens

C. septicum

Clostridium sp.

often a marker organism for a malignancy in the GI tract

Clostridium botulinum

aka Canned food bacillus

Foodborne botulism

result from ingestion of preformed botulinum toxin

types associated with Foodborne botulism

infant botulism

• ingestion of C. botulinum spores

This type of botulism is associated with contaminated honey - food most commonly associated

Wound botulism

type of botulism:

contamination of wounds with spores of C. botulinum

• prevents the release of acetycholine in the neurons which leads to paralysis and death

Why is C. botulinum lethal?

C. botulinum

causes Flappy Baby syndrome

B-hemolysis

hemolytic pattern of C. Botulinum

C. tetani

aka Tack head bacillus

tetanospasmin

neurotoxin produced by C. tetani which causes Tetanus

C. tetanus

This causes spastic type of paralysis, with continuous muscular spasm leading to trismus (lockjaw), risus sardonicus (distorted grin), and difficulty breathing

diptheria-tetanus-acellular pertussis (DTaP) vaccine

vaccine for tetanus

Cycloserine Cefoxitin Fructose Agar (CCFA)

ideal plating medium for C. difficile

C. difficile

This bacteria:

BAP - “horse stable” odor; non-hemolytic

Actinomyces israelli

• results to a lumpy jaw (maxillary region)

• erupt to the surface and drain pus that may contain so-called sulfur granules

ID:
* White, opaque and resemble “molar tooth”

• Gram positive, branching filamentous rods

Propionibacterium acnes

Associated with inflammatory process in acne

• also cause subacute endocardities

P. acnes

ID:

Gramstain: Gram positive pleomorphic diptheroid appearance

Colonial Appearance: Small and white to large yellowish tan

Bifidobacterium spp.

• Colonial Appearance • convex, cream to white, smooth, glistening, and soft

• In mixed infections of abdomen, pelvis and GUT

Bifidobacterium spp.

• variable in shape, ranging from coccobacilli to long branching rods • ends of the cells may be pointed, bent, club-shaped, spatulated, or bifurcated (forked)

True

T/F:

Anaerobic Gram- Negative Bacilli are endogenous, found in oral cavity and GI tract

Anaerobic Gram- Negative Bacilli

• B. fragilis group

• Porphyromonas,

• Prevotella

• Fusobacterium

Bacteroides fragilis

• Gray and non hemolytic in BAP

• Dark gray with dark gray zone (esculin hydrolysis) and precipitate (bile) in Bacteroides Bile esculin agar

Bacteroides fragilis

• Growth in 20% bile (resistantto bile)

• Saccharolytic

• Bile esculin hydrolysis positive

• Resistant to kanamycin, vancomycin and colistin

Prevotella spp.

• Non hemolytic and fluoresces brickred when viewed in 365 nm UVlight.

• Black pigment in Lakedkanamycin‐ vancomycin blood agar

Prevotella spp.

Some Prevotella spp: have protoprohyrin which is a brown to black pigment

Porphyromonas spp.

• • Dark brown to black, more mucoid than Prevotella (BAP)

• • Fluoresces brick red when viewed under 365 nm UVlight

• • Black pigment in Laked kanamycin‐ vancomycin blood agar

• Do not ferment carbohydrates (assaccharolytic)

• • Inhibited by 20%bile

• • susceptible toVancomycin and resistant to colistin

• • Most __________ spp. are spot indole–positive

Fusobacterium nucleatum

Gram negative spindle‐shaped with pointed or tapered ends (fusiform)

Finegoldia magna

• most pathogenic of the anaerobic cocci and the one most often isolated in pure culture.

Anaerobic Cocci	Gram stain
Veillonella	(-)
Peptostreptococcus	(+)

Anaerobic Cocci

Anaerobic Cocci	Gram stain
Veillonella
Peptostreptococcus