Clinical Importance of Anaerobes and Identification Methods

Direct Microscopic Examination

Identifies pathogens in anaerobic specimens.

Polymicrobial Infection

Infection caused by multiple microbial species.

Monomicrobial Infection

Infection caused by a single microbial species.

Presumptive Identification

Initial identification based on observable characteristics.

Gram Stain

Staining technique to classify bacteria.

Methanol Fixative

Used instead of heat for Gram staining.

Safranin Counterstain

Stain used to visualize Gram-negative bacteria.

Clostridia

Large, gram-positive bacilli associated with anaerobic infections.

Fusobacteria sp

Thin, tapered gram-negative bacilli.

Veillonella sp

Tiny, oval gram-negative cocci, gram-variable.

Bacteroides

Gram-negative coccobacilli, part of normal flora.

Porphyromonas

Gram-negative coccobacilli, often found in infections.

Prevotella

Gram-negative coccobacilli, associated with oral infections.

Anaerobic Media

Specialized media for culturing anaerobic bacteria.

Blood Agar

Nonselective medium for growing various bacteria.

Bacteroides Bile Esculin Agar

Selective medium for isolating Bacteroides species.

Kanamycin and Vancomycin

Antibiotics used to inhibit certain bacteria.

Thioglycollate Broth

Used for anaerobic culture of specimens.

Aerobic Culture Media

Media for culturing bacteria in oxygen.

PRAS Media

Plated media stored under anaerobic conditions.

Anaerobic Chambers

Environments for working with anaerobic organisms.

Glove Boxes

Contain gloves for handling anaerobic cultures.

Anaerobe Jars

Containers for creating anaerobic conditions.

Biobags

Flexible bags for anaerobic culture incubation.

Catalysts in Chambers

Remove residual oxygen using palladium-coated pellets.

Desiccant

Absorbs water produced during oxygen removal.

Oxygen Indicator

Changes color based on oxygen presence.

Incubation in Chambers

Conducted in oxygen-free environments for anaerobes.

Gloveless Boxes

Alternative to glove boxes for anaerobic work.

Anaerobic jars

Containers for cultivating anaerobic bacteria.

Envelope gas generator

Device that creates anaerobic conditions.

Waterless systems

Modern anaerobic jars without water requirement.

Hydrogen gas

Explosive gas produced in anaerobic jars.

Methylene blue indicator

Strip that verifies anaerobic conditions.

Oxygen exposure

Harmful for anaerobes within first 48 hours.

Anaerobic pouches

Sealed bags for incubating anaerobic cultures.

GasPak pouch

Type of anaerobic pouch for testing.

Clinical Laboratory Standards Institute (CLSI)

Organization providing guidelines for lab practices.

M35-A2 guidelines

CLSI document for identifying bacteria and yeast.

Presumptive identification

Initial identification based on observable traits.

Timely information

Quick results regarding anaerobic presence.

Mixed infection

Infection involving multiple types of microorganisms.

Foul odor

Sign of anaerobes like C. difficile.

Bacteroides bile-esculin agar (BBE)

Selective media for anaerobic bacteria growth.

Double zone of hemolysis

Characteristic of C. perfringens on blood agar.

Brick-red fluorescence

Indicator for Porphyromonas or Prevotella on KVLB.

Aerotolerance test

Determines anaerobic or facultative nature of bacteria.

Chocolate agar plate

Medium used for aerotolerance testing.

Incubation temperature

35 to 37 degrees C for 48 hours.

Colony morphology

Physical characteristics of bacterial colonies.

Gram-stain reaction

Determines bacterial cell wall characteristics.

Pure culture

Isolated bacterial population for testing.

Subculture plate

Secondary plate for further bacterial growth.

Oxygen-free holding system

Storage for anaerobic cultures before examination.

Microscopic exam

Visual analysis of bacteria under a microscope.

Incubation in CO2

Growth condition for certain anaerobic bacteria.

Growth examination

Assessment of bacterial proliferation after incubation.

Presumptive identification

Initial assessment of clinically significant anaerobes.

Rapid tests

Quick methods for identifying anaerobic bacteria.

Fluorescence

Detection method using UV light for bacteria.

Catalase test

Distinguishes Clostridium (catalase neg) from Bacillus.

Spot Indole test

Differentiates Propionibacterium acnes from other species.

Urease test

Identifies C. sordellii as urease-positive Clostridium.

Motility test

Determines motility of anaerobic bacteria via wet mount.

Special potency antimicrobial disks

Disks used to test bacterial susceptibility to antibiotics.

Sodium polyanethol sulfonate disk

Tests susceptibility of Peptostreptococcus anaerobius.

Nitrate disk

Assesses nitrate reduction to nitrite or nitrogen gas.

Bile disk

Tests growth in 20% bile for B. fragilis group.

Lecithinase

Enzyme cleaving lecithin, indicating Clostridia species.

Lipase

Enzyme hydrolyzing triglycerides, creates iridescent sheen.

Proteolytic enzymes

Degrade proteins, forming clear zones around colonies.

Egg yolk agar (EYA)

Medium for testing lecithinase, lipase, proteolytic activities.

Porphyromonas spp.

Exhibits brick-red fluorescence under UV light.

Fusobacterium nucleatum

Shows chartreuse fluorescence under UV light.

Veillonella spp.

Displays red fluorescence when exposed to UV light.

Clostridium ramosum

Susceptible to vancomycin and kanamycin, resistant to colistin.

Campylobacter sp.

Motile anaerobe identified via motility test.

Mobiluncus sp.

Another motile anaerobe identified via motility test.

Gram-Stain Morphology

Visual classification method for anaerobic isolates.

Double-zone beta hemolysis

Characteristic of C. perfringens on SBA.

Boxcar-shaped bacilli

Morphology of C. perfringens under microscopic examination.

Special potency disk results

Interpretation of bacterial susceptibility to antibiotics.

Antimicrobial susceptibility

Bacteria's resistance or sensitivity to specific antibiotics.

C. difficile

Produces horse stable odor; fluoresces chartreuse under UV.

C. septicum

Rapidly growing, smooth swarming colonies; thin rods.

Peptostreptococcus sp.

Small, peaked circular colonies; gram positive cocci.

Peptococcus niger

Black to olive green colonies; light gray when exposed.

Propionibacterium acnes

Catalase- and indole-positive; coryneform rods.

C. perfringens

Double zone of hemolysis; complete and partial beta hemolysis.

Bacteroides fragilis group

Large gray-black colonies on BBE agar.

B. ureolyticus

Translucent pitting colonies; no growth on BBE.

Bilophila wadsworthia

Translucent colonies with black fish eye center.

Fusobacterium nucleatum

Ground-glass colonies; long, slender gram-negative rods.

Prevotella

Fluoresce brick red; grow on anaerobic blood agar.

Veillonella

Small, translucent or opaque gram-negative cocci.

Sterile sites

Require full identification for accurate diagnosis.

Biochemical minisystems

Used for definitive identification of anaerobes.

Gas-liquid chromatography

Analyzes metabolic end products for identification.

Cellular fatty acid analysis

Identifies bacteria using gas-liquid chromatography.

16S ribosomal sequencing

Molecular method for bacterial identification.