Sexually Transmitted Infections: Symptoms, Causes, and Treatment
Nongonococcal Urethritis (NGU)
Definition:
Nongonococcal urethritis (NGU) is an inflammation of the urethra caused by infections other than Neisseria gonorrhoeae. It is a common condition in sexually active individuals and a leading cause of urethritis.
Etiology:
The most common causes of NGU include:
- Chlamydia trachomatis – The primary causative agent.
- Mycoplasma genitalium – Often linked to recurrent or resistant cases.
- Ureaplasma urealyticum – Found in the urogenital tract.
- Herpes Simplex Virus
Bacterial and Viral Infections: Diagnosis and Treatment
Diphtheria: A Serious Bacterial Infection
Diphtheria is a serious bacterial infection of the throat.
Etiological Agents
The causative organism for diphtheria is Corynebacterium diphtheriae, a gram-positive, non-spore-forming, club-shaped bacterium.
Rarely, other Corynebacterium species (like Corynebacterium ulcerans and Corynebacterium pseudotuberculosis) may cause diphtheria-like symptoms, but C. diphtheriae is the primary cause.
Pathogenesis of Diphtheria
- Transmission: The bacteria are transmitted through
Respiratory Infections: Symptoms, Causes, and Treatment
BCG Vaccine
Full Form: Bacillus Calmette-Guérin vaccine.
Purpose: Prevents tuberculosis (TB), especially severe forms like miliary TB and tuberculous meningitis in children.
Type: Live attenuated vaccine derived from Mycobacterium bovis.
Administration:
- Route: Intradermal.
- Site: Deltoid region of the left arm.
- Age: At birth or within the first year.
Mechanism: Induces cellular immunity (T-cell response).
Adverse Effects: Local swelling, ulcer formation, regional lymphadenopathy, keloid scar.
Contraindications:
Read MorePertussis, Aspergillosis, Mucormycosis, and Other Infectious Diseases
Laboratory Diagnosis of Pertussis
Causative Agent: Bordetella pertussis, a gram-negative coccobacillus.
Pathogenesis
The bacteria attach to the ciliated epithelial cells of the respiratory tract using adhesins (filamentous hemagglutinin, fimbriae).
B. pertussis produces toxins:
- Pertussis toxin: Increases cAMP levels, leading to mucus production and tissue damage.
- Tracheal cytotoxin: Paralyzes and damages ciliated epithelial cells.
This causes characteristic cough and mucus accumulation.
Clinical Stages:
Read MoreInfectious Diseases: Listeriosis, Meningitis, Coxsackievirus, Rabies, and More
Listeriosis
Definition
Listeriosis is a severe infection caused by Listeria monocytogenes, affecting neonates, pregnant women, the elderly, and immunocompromised individuals.
Causative Organism
Organism: Listeria monocytogenes
Characteristics: Gram-positive, facultative intracellular bacterium, grows at low temperatures.
Pathogenesis
- Ingested through contaminated food (e.g., unpasteurized dairy).
- Crosses the intestinal barrier, survives inside host cells, and spreads to organs like the brain (causing meningitis)
Common Bacterial and Fungal Infections: Symptoms and Treatments
Clinical Condition: Gas Gangrene (Clostridial Myonecrosis)
Etiological Agents:
- Clostridium perfringens (most common)
- Clostridium septicum
- Clostridium novyi
- Clostridium histolyticum
- Clostridium sordellii
Pathogenesis
- Entry: Clostridial spores enter deep, anaerobic tissue (crushed muscles contaminated with soil).
- Anaerobic Growth: Necrotic tissue and poor blood supply provide an anaerobic environment for spore germination.
- Toxin Production:
- Alpha-toxin (lecithinase): Damages cell membranes, causes hemolysis