In-Depth Notes on Major Bacterial Diseases

Introduction to Major Bacterial Diseases

• Caused by bacteria
• Laboratory confirmation necessary
• Bacterial Diseases Manifestations:
  • Same disease can show different manifestations.
  • Different bacteria can cause similar symptoms.
• Considerations for Understanding Bacterial Diseases:
  • Organ systems affected
  • Mode of transmission
  • Signs and symptoms

Classification of Bacteria

• Classified by:
  • Shape
  • Gram Staining
  • Acid Fast Staining
  • Spore Formation
  • Intracellular Survival

Gram Negative Cocci

• Notable genera:
  • Neisseria
  • Branhamella
  • Veilonella
  • Acidaminococcus
  • Megasphaera

Gram Positive Bacilli

• Examples:
  • Bacillus
  • Bifidobacterium
  • Nocardia
  • Erysipelothrix
  • Listeria
  • Streptomyces
  • Actinomyces
  • Mycobacterium
  • Corynebacterium
  • Clostridium
  • Arcanobacterium
  • Propionibacterium
  • Lactobacillus
  • Eubacterium

Acid-Fast Bacilli

• Mycobacterium
• Nocardia

Spore Formers

• Examples:
  • Bacillus
  • Clostridium

Laboratory Identification

• Methods:
  • Direct staining
  • Inoculation on primary plates (16-24 hours)
  • Staining and biochemical testing for positive growth
  • Sensitivity testing (16-24 hours)
  • Results documented

Minimum Competency Understanding

• Key Aspects:
  • Identify disease
  • Organ system affected
  • Clinical manifestations
  • Causative agent
  • Reservoir
  • Mode of transmission

Bacterial Diseases of the Skin

Acne

• Clinical Manifestation: Inflamed, infected abscesses
• Causative Agent: Propionibacterium acnes
• Transmission: Non-communicable

Anthrax/Wool Sorter's Disease

• Forms: Cutaneous, Pulmonary, Gastrointestinal
• Clinical Manifestation: Black eschar
• Causative Agent: Bacillus anthracis
• Reservoirs: Animals and soil
• Transmission: Through wounds, inhalation, ingestion

Gas Gangrene/Myonecrosis

• Clinical Manifestation: Necrosis from ischemia
• Causative Agent: Clostridium perfringens
• Reservoir: Soil
• Transmission: Deep puncture wounds

Leprosy/Hansen’s Disease

• Types: Lepromatous (skin nodules) and Tuberculoid (few lesions)
• Causative Agent: Mycobacterium leprae
• Reservoir: Armadillos
• Transmission: Inhalation or broken skin; tuberculoid is non-contagious

Staphylococcal Skin Infections

• Clinical Manifestations: Folliculitis, Furuncles, Carbuncles, Impetigo, SSSS
• Causative Agent: Staphylococcus aureus
• Transmission: Direct contact with purulent lesions or carriers

Streptococcal Skin Infections

• Conditions: Impetigo, Scarlet fever, Erysipelas, Necrotizing fasciitis
• Causative Agent: Streptococcus pyogenes
• Transmission: Direct contact, respiratory droplets, indirect contact

Bacterial Diseases of the Ears

Otitis Externa/Swimmer’s Ear

• Clinical Manifestation: Itching, malodorous discharge
• Causative Agents: Proteus vulgaris, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus
• Reservoir: Fomites
• Transmission: Swimming in contaminated pools

Otitis Media

• Clinical Manifestations: Severe headache, temporary hearing loss, eardrum rupture
• Causative Agents: Streptococcus pneumoniae, Streptococcus pyogenes
• Transmission: Introduction of nasopharynx microflora to the middle ear

Bacterial Diseases of the Eyes

Conjunctivitis/Pink Eye

• Clinical Manifestation: Irritation, reddening, mucopurulent discharge
• Causative Agents: Haemophilus influenzae, Streptococcus pneumoniae, other bacteria
• Transmission: Highly contagious, contact with eye or respiratory discharges

Gonococcal Conjunctivitis/Gonorrheal Ophthalmia Neonatorum

• Clinical Manifestation: Acute redness, swelling, purulent discharge
• Causative Agent: Neisseria gonorrhoeae
• Transmission: Contact with genital discharges

Bacterial Diseases of the Respiratory Tract

Diphtheria

• Clinical Manifestation: Formation of a tough grayish-white membrane in throat, difficulty in breathing
• Causative Agent: Corynebacterium diphtheriae
• Transmission: Airborne droplets, direct contact, fomites

Pneumonia

• Clinical Manifestation: Productive cough, chest pain, fever
• Causative Agents: Streptococcus pneumoniae, Haemophilus influenzae
• Transmission: Droplet inhalation, direct contact

Bacterial Diseases of the Gastrointestinal System

Cholera

• Clinical Manifestation: Profuse watery stools, dehydration
• Causative Agent: Vibrio cholerae serogroup 01
• Transmission: Fecal-oral, mechanical vectors

Salmonellosis

• Clinical Manifestation: Gastroenteritis, fever, dehydration
• Causative Agent: Salmonella typhimurium
• Transmission: Fecal-oral

Bacterial Diseases of the Central Nervous System

Meningitis

• Clinical Manifestation: Fever, headache, stiff neck, vomiting
• Causative Agents: Streptococcus pneumoniae, Neisseria meningitidis
• Transmission: Respiratory droplets, bloodstream introduction to CNS

Listeriosis

• Clinical Manifestation: Meningoencephalitis in immunocompromised patients
• Causative Agent: Listeria monocytogenes
• Transmission: Ingestion of contaminated food

Conclusion

• Understanding various bacterial diseases is crucial for effective diagnosis and treatment.
• Laboratory identification plays a significant role in determining the appropriate course of action.