• Plaque & Bacteria:
  • Plaque: Mainly extracellular polysaccharides.
  • Pellicle: Thin film post-cleaning.
  • Bacteria in 1g plaque: 2 × 10¹¹.
  • Early plaque: Gram-positive.
  • Saliva: Streptococci dominate.
  • First oral colonizer: S. sanguis.
  • Secondary colonizer: S. mutans.
  • Red Complex: Most associated with periodontal disease.
  • Green Complex: A. actinomycetemcomitans, E. corrodens, Capnocytophaga.
• Tests & Toxins:
  • BANA test: Detects P. gingivalis, T. denticola, B. forsythia.
  • Leukotoxin (116-kDa): Secreted by A. actinomycetemcomitans.
  • Myeloperoxidase: Prevents A. viscosus attachment.
• Immunoglobulins:
  • Saliva: IgA.
  • GCF: IgG.
• GCF Lymphocyte Ratio: T:B = 1:3.
• TLRs: Absent on bacterial cells.

Infection Timeline Post-BMT

Phase I: Pre-engraftment (0-30 days)

• Earliest infection: Herpes Simplex Virus (HSV)
• Other pathogens: Bacteria, Candida, Aspergillus
• Risk factors: Neutropenia, mucositis, central lines

Phase II: Early post-engraftment (30-100 days)

• ~7th week (50 days): Interstitial Pneumonitis peak incidence
• Causes: CMV, Pneumocystis jirovecii, idiopathic
• GVHD: Acute graft-versus-host disease peak

Phase III: Late post-engraftment (>100 days)

• Chronic GVHD: Major concern
• Encapsulated bacteria: Due to functional asplenia
• Varicella-zoster virus: Reactivation common

Specific Infectious Complications

CMV Disease

• Timeline: 30-100 days post-BMT
• High risk: CMV+ recipient or donor
• Manifestations: Pneumonitis, gastroenteritis, retinitis

Interstitial Pneumonitis (IP)

• Peak incidence: ~7th week (50 days) post-BMT
• Types:
  • CMV pneumonitis (most common infectious cause)
  • Idiopathic IP
  • Pneumocystis pneumonia
• Mortality: High, especially CMV pneumonitis

Prophylactic Strategies

• Antibacterial: Fluoroquinolones
• Antifungal: Fluconazole or newer azoles
• Antiviral: Acyclovir for HSV/VZV
• PCP prophylaxis: Trimethoprim-sulfamethoxazole
• CMV monitoring: Pre-emptive therapy based on viral load

GVHD Prevention

• Immunosuppression: Methotrexate + calcineurin inhibitors
• T-cell depletion: In some protocols
• HLA matching: Reduces risk significantly

🔬 Key Features & Forms

• Most infective form: Cavitary lesion
• Primary TB Presentation: Unilateral hilar lymphadenopathy
• Rich focus: Meninges (associated with TB meningitis)
• Cavitation: Absent in HIV-associated or primary TB

💡 Special Manifestations

• Hypersensitivity to Mycobacteria: Phlyctenular conjunctivitis
• Poncet’s disease: Joint pains without active arthritis
• Miliary TB: Mantoux test negative
• Recurrent hemoptysis source: Bronchial artery

💊 Drug Details

• Streptomycin: Not used in TB meningitis
• Bedaquiline: New drug for MDR-TB

Ecological Succession of Biofilm in Dental Plaque

Overview of Biofilm Formation

Biofilm formation on tooth surfaces is a dynamic process characterized by ecological succession, where microbial communities evolve over time. This process transitions from an early aerobic environment dominated by gram-positive facultative species to a later stage characterized by a highly oxygen-deprived environment where gram-negative anaerobic microorganisms predominate.

Stages of Biofilm Development

1. Initial Colonization:

   • Environment: The initial phase occurs in an aerobic environment.
   • Primary Colonizers:
     • The first bacteria to colonize the pellicle-coated tooth surface are predominantly gram-positive facultative microorganisms.
     • Key Species:
       • Actinomyces viscosus
       • Streptococcus sanguis
   • Characteristics:
     • These bacteria can thrive in the presence of oxygen and play a crucial role in the establishment of the biofilm.

2. Secondary Colonization:

   • Environment: As the biofilm matures, the environment becomes increasingly anaerobic due to the metabolic activities of the initial colonizers.
   • Secondary Colonizers:
     • These microorganisms do not initially colonize clean tooth surfaces but adhere to the existing bacterial cells in the plaque mass.
     • Key Species:
       • Prevotella intermedia
       • Prevotella loescheii
       • Capnocytophaga spp.
       • Fusobacterium nucleatum
       • Porphyromonas gingivalis
   • Coaggregation:
     • Secondary colonizers adhere to primary colonizers through a process known as coaggregation, which involves specific interactions between bacterial cells.

3. Coaggregation Examples:

   • Coaggregation is a critical mechanism that facilitates the establishment of complex microbial communities within the biofilm.
   • Well-Known Examples:
     • Fusobacterium nucleatum with Streptococcus sanguis
     • Prevotella loescheii with Actinomyces viscosus
     • Capnocytophaga ochracea with Actinomyces viscosus

Implications of Ecological Succession

• Microbial Diversity: The transition from gram-positive to gram-negative organisms reflects an increase in microbial diversity and complexity within the biofilm.
• Pathogenic Potential: The accumulation of anaerobic gram-negative bacteria is associated with the development of periodontal diseases, as these organisms can produce virulence factors that contribute to tissue destruction and inflammation.
• Biofilm Stability: The interactions between different bacterial species through coaggregation enhance the stability and resilience of the biofilm, making it more challenging to remove through mechanical cleaning.

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Subgingival and Supragingival Calculus

Overview of Calculus Formation

Calculus, or tartar, is a hardened form of dental plaque that can form on both supragingival (above the gum line) and subgingival (below the gum line) surfaces. Understanding the differences between these two types of calculus is essential for effective periodontal disease management.

Subgingival Calculus

1. Color and Composition:

   • Appearance: Subgingival calculus is typically dark green or dark brown in color.
   • Causes of Color:
     • The dark color is likely due to the presence of matrix components that differ from those found in supragingival calculus.
     • It is influenced by iron heme pigments that are associated with the bleeding of inflamed gingiva, reflecting the inflammatory state of the periodontal tissues.

2. Formation Factors:

   • Matrix Components: The subgingival calculus matrix contains blood products, which contribute to its darker coloration.
   • Bacterial Environment: The subgingival environment is typically more anaerobic and harbors different bacterial species compared to supragingival calculus.

Supragingival Calculus

1. Formation Factors:

   • Dependence on Plaque and Saliva:
     • The degree of supragingival calculus formation is primarily influenced by the amount of bacterial plaque present and the secretion of salivary glands.
     • Increased plaque accumulation leads to greater calculus formation.

2. Inorganic Components:

   • Source: The inorganic components of supragingival calculus are mainly derived from saliva.
   • Composition: These components include minerals such as calcium and phosphate, which contribute to the calcification process of plaque.

Comparison of Inorganic Components

• Supragingival Calculus:

  • Inorganic components are primarily sourced from saliva, which contains minerals that facilitate the formation of calculus on the tooth surface.

• Subgingival Calculus:

  • In contrast, the inorganic components of subgingival calculus are derived mainly from crevicular fluid (serum transudate), which seeps into the gingival sulcus and contains various proteins and minerals from the bloodstream.

Treatment Phases

1. Phase 1: Non – surgical
2. Phase 2: Surgical
3. Phase 3: Restorative
4. Phase 4: Maintenance Must progress through Phase 1 → 4 before Phase 2 or 3

Merin's Classification

• Class A: 6 months – 1 year recall
• Class B: 3 – 4 months recall
• Class C: 1 – 3 months recall

Zones of Periodontal Disease

Listgarten described four distinct zones that can be observed in periodontal lesions. These zones may blend with each other and may not be present in every case.

Zones of Periodontal Disease

1. Zone 1: Bacterial Zone

   • Description: This is the most superficial zone, consisting of a diverse array of bacteria.
   • Characteristics:
     • The bacterial zone is primarily composed of various microbial species, including both pathogenic and non-pathogenic bacteria.
     • This zone is critical in the initiation and progression of periodontal disease, as the presence of specific bacteria can trigger inflammatory responses in the host.

2. Zone 2: Neutrophil Rich Zone

   • Description: This zone contains numerous leukocytes, predominantly neutrophils.
   • Characteristics:
     • The neutrophil-rich zone is indicative of the body’s immune response to the bacterial invasion.
     • Neutrophils are the first line of defense and play a crucial role in phagocytosing bacteria and releasing inflammatory mediators.
     • The presence of a high number of neutrophils suggests an acute inflammatory response, which is common in active periodontal disease.

3. Zone 3: Necrotic Zone

   • Description: This zone consists of disintegrated tissue cells, fibrillar material, remnants of collagen fibers, and spirochetes.
   • Characteristics:
     • The necrotic zone reflects tissue destruction and is characterized by the presence of dead or dying cells.
     • Fibrillar material and remnants of collagen fibers indicate the breakdown of the extracellular matrix, which is essential for maintaining periodontal tissue integrity.
     • Spirochetes, which are associated with more aggressive forms of periodontal disease, can also be found in this zone, contributing to the necrotic process.

4. Zone 4: Zone of Spirochetal Infiltration

   • Description: This zone consists of well-preserved tissue that is infiltrated with large and medium spirochetes.
   • Characteristics:
     • The zone of spirochetal infiltration indicates a more chronic phase of periodontal disease, where spirochetes invade the connective tissue.
     • The presence of well-preserved tissue suggests that while spirochetes are present, the tissue has not yet undergone extensive necrosis.
     • This zone is significant as it highlights the role of spirochetes in the pathogenesis of periodontal disease, particularly in cases of necrotizing periodontal diseases.