All point in the study guide

What are the two main types of immune defenses?

Innate (non-specific) and adaptive (specific).

How can host genetics affect the oral microbiota?

Genetics can influence microbiota composition, disease susceptibility, and microbial variation.

What did the Human Microbiome Project identify?

A ‘core microbiome’ common to all individuals and variable accessory genes.

Can ethnicity affect oral microbiota?

Yes, some ethnic groups have distinct microbial signatures.

Which host factors influence susceptibility to periodontal disease?

Gender, host genetics, and ethnicity.

How does diet affect the oral microbiome?

Frequent sugar intake lowers pH, promotes aciduric bacteria, and increases caries risk.

How does smoking affect periodontal disease?

Smoking increases risk, disturbs subgingival microbiota, and promotes periodontal pathogens.

What happens to oral microbiota after smoking cessation?

Levels and prevalence of periodontal pathogens decrease.

What is colonization?

Attachment and growth of microorganisms on host surfaces.

What is microbial classification?

Arrangement of organisms based on similarities and differences.

What is microbial identification?

Determining where a new isolate belongs (genus/species).

What is taxonomy?

Nomenclature and identification of microorganisms.

Which methods are used to classify microbes?

Morphological, physiological, chemotaxonomy, serology, genetic relatedness.

Which genes are used to determine microbial genetic relatedness?

16S rRNA genes.

What is a type strain?

Primary strain representing a species.

What are biotypes?

Strains with unique biochemical or physiological properties.

What are serotypes?

Strains with distinctive antigenic compositions.

Which collections hold microbial strains?

American Type Culture Collection (ATCC).

What are conventional microbial identification methods?

Gram staining, cellular morphology, antibodies, nucleic acid probes.

Why are molecular methods important in microbial ecology?

Detect unculturable species and their growth requirements.

What difficulties arise from advances in microbial classification?

Reclassification, interpreting older literature, comparing data.

Which group of Gram-positive cocci lacks catalase?

Streptococcus.

What are the four major Streptococcus groups?

Mutans, Salivarius, Anginosus, Mitis.

Which Streptococcus group is linked to dental caries?

Mutans.

Which Streptococcus group prefers mucosa and the tongue?

Salivarius.

Which Streptococcus group is associated with abscesses?

Anginosus.

Which Streptococcus group binds salivary α-amylase?

Mitis.

Which Gram-positive rods are linked to dental plaque and gingivitis?

Actinomyces.

Which rods are acidogenic and found in caries?

Lactobacillus.

Which Gram-negative cocci contribute to plaque formation?

Neisseria and Veillonella.

Which Gram-negative rods are facultative anaerobes linked to aggressive periodontitis?

Aggregatibacter actinomycetemcomitans.

Which Gram-negative rods are obligate anaerobes and pigmented?

Prevotella and Porphyromonas.

Which microbes lack a cell wall?

Mycoplasma.

Which fungus is most prevalent in the oral cavity?

Candida albicans.

Which archaea is found in the oral cavity?

Methanobrevibacter oralis.

Which viruses can be detected in the mouth?

HSV-1, HSV-2, CMV, HPV, HIV.

Which protozoa are common in the oral cavity?

Trichomonas tenax, Entamoeba gingivalis.

How does colonization resistance work?

Prevents pathogen colonization via attachment, nutrient competition, unfavorable conditions, inhibitory substances.

What are prebiotics?

Molecules that promote growth of beneficial microbes.

How do oral microbes contribute to nitrate metabolism?

Convert dietary nitrate to nitrite, affecting blood pressure, gastric health, and antimicrobial defense.

Which factors influence microbial acquisition in infants?

Mode of delivery, feeding type (breast vs formula), vertical transmission from mother.

Which bacteria are pioneer species in oral colonization?

Streptococcus salivarius and early Streptococcus species.

What is autogenic microbial succession?

Microbial community changes influenced by microbial activity.

What is allogenic microbial succession?

Community changes due to non-microbial factors.

What is microbial homeostasis?

Stable oral microbiota coexistence with the host.

Which techniques are used to determine oral microbiota composition?

Culture-dependent methods, microscopy, molecular methods, in situ models.

What are the main sampling methods for oral microbiota?

Swabbing, scraping, saliva collection, plaque collection.

Why is subgingival plaque hard to sample?

Inaccessibility, anaerobic nature, biofilm structure.

How should samples be transported for culture?

Quickly, with reducing agents to preserve anaerobes.

What is the purpose of vortexing or sonication in sample prep?

Disperse clumps for accurate colony counts.

What is a limitation of culture methods?

Only 50–70% of microbiota can be cultured.

Which microscopy methods reveal plaque architecture?

Confocal laser scanning microscopy, electron microscopy.

Which oral surfaces have the highest microbial diversity?

Dorsum of the tongue.

Which microbes dominate the lips and vestibule?

Streptococci, occasional Veillonella, Haemophilus, Candida albicans with damage/dentures.

Which microbes dominate the cheeks?

Streptococci.

Which microbes dominate the palate?

Streptococci and Actinomyces, lower levels of Veillonella, Haemophilus, Gram-negative anaerobes.

Which microbes are most abundant on teeth and dentures?

Gram-positive rods (Actinomyces), obligate anaerobes.

Does saliva have a resident microbiota?

No, microbes are mostly transient from other surfaces.

How is saliva used to assess caries risk?

Measuring mutans streptococci and lactobacilli levels.