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Questions and Answers
What is the common name for Neisseria gonorrhoeae?
What is the common name for Neisseria gonorrhoeae?
Gonorrhea or Gonococcus
In what shape does Neisseria gonorrhoeae appear?
In what shape does Neisseria gonorrhoeae appear?
Neisseria gonorrhoeae is an anaerobic bacteria.
Neisseria gonorrhoeae is an anaerobic bacteria.
False (B)
What is the primary method of transmission for Neisseria gonorrhoeae?
What is the primary method of transmission for Neisseria gonorrhoeae?
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What are the two main types of virulence factors associated with Neisseria gonorrhoeae?
What are the two main types of virulence factors associated with Neisseria gonorrhoeae?
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Which of the following is NOT a typical symptom of gonorrhea in men?
Which of the following is NOT a typical symptom of gonorrhea in men?
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What is the name of the bacterium that causes cholera?
What is the name of the bacterium that causes cholera?
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Cholera is a highly contagious disease transmitted through the air.
Cholera is a highly contagious disease transmitted through the air.
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What is the characteristic shape of Vibrio cholerae?
What is the characteristic shape of Vibrio cholerae?
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What is the primary toxin produced by Vibrio cholerae?
What is the primary toxin produced by Vibrio cholerae?
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Cholera is often characterized by ______
Cholera is often characterized by ______
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Which of the following is a common diagnostic method for Vibrio cholerae?
Which of the following is a common diagnostic method for Vibrio cholerae?
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Vaccination for cholera offers complete and lifelong protection.
Vaccination for cholera offers complete and lifelong protection.
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What are the main types of bacteria that cause pneumonia?
What are the main types of bacteria that cause pneumonia?
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Mycoplasma pneumoniae is a type of bacteria that has a distinct cell wall.
Mycoplasma pneumoniae is a type of bacteria that has a distinct cell wall.
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What is the primary mode of transmission for Mycoplasma pneumoniae?
What is the primary mode of transmission for Mycoplasma pneumoniae?
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Which of the following is considered a hallmark symptom of Mycoplasma pneumoniae infection?
Which of the following is considered a hallmark symptom of Mycoplasma pneumoniae infection?
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Diagnosis of Mycoplasma pneumoniae is usually done using a simple urine test.
Diagnosis of Mycoplasma pneumoniae is usually done using a simple urine test.
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Infections with Mycoplasma pneumoniae are more common during ______
Infections with Mycoplasma pneumoniae are more common during ______
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What is the name of the bacterium that is a common cause of sexually transmitted infections and also causes eye infections?
What is the name of the bacterium that is a common cause of sexually transmitted infections and also causes eye infections?
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Chlamydia trachomatis is a type of Gram-positive bacteria
Chlamydia trachomatis is a type of Gram-positive bacteria
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What are the two main forms of Chlamydia trachomatis?
What are the two main forms of Chlamydia trachomatis?
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How is Chlamydia trachomatis primarily transmitted?
How is Chlamydia trachomatis primarily transmitted?
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Which of the following is NOT a typical clinical manifestation of Chlamydia trachomatis infection in women?
Which of the following is NOT a typical clinical manifestation of Chlamydia trachomatis infection in women?
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Diagnosis of Chlamydia trachomatis relies primarily on chest X-ray results
Diagnosis of Chlamydia trachomatis relies primarily on chest X-ray results
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A common preventive measure for Chlamydia trachomatis infection involves using ______
A common preventive measure for Chlamydia trachomatis infection involves using ______
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What are some of the public health measures recommended to prevent the spread of Chlamydia trachomatis?
What are some of the public health measures recommended to prevent the spread of Chlamydia trachomatis?
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Study Notes
Medical Microbiology Lecture (11)
- The lecture covers an overview of bacterial infections, focusing on Neisseria gonorrhoeae, Helicobacter pylori, Vibrio cholerae, Mycoplasma pneumoniae, and Chlamydia trachomatis.
Neisseria gonorrhoeae
- Common Name: Gonorrhea or Gonococcus
- Transmission: Sexually transmitted infection (oral, vaginal, or anal intercourse).
-
Characteristics:
- Gram-negative diplococci (paired, coffee-bean shaped)
- Aerobic (requires oxygen to grow)
- Size: 0.6-1.0 µm
-
Virulence Factors:
- Pili/Fimbriae: Attachment to host cells
- Outer Membrane Proteins (OMPs): Immune evasion
- IgA Protease: Degrades IgA antibodies (mucosal immunity)
- Lipooligosaccharide (LOS): Endotoxin, contributes to inflammation
-
Clinical Manifestations:
- Men: Painful urination (dysuria), yellowish/greenish discharge, epididymitis
- Women: Increased vaginal discharge, painful urination, pelvic pain, lower abdominal pain, abnormal vaginal bleeding
- Other: Rectal infections (pain, itching, discharge, bleeding)
- Neonatal: Eye infection (conjunctivitis) in newborns
-
Laboratory Diagnosis:
- Sample Collection: Urethral swabs (men), endocervical swabs (women), eye swabs (newborns)
- Microscopy: Gram-negative diplococci
- Culture: Chocolate agar
- Molecular Tests (available)
Helicobacter pylori (H. pylori)
- Description: A bacterium that infects the stomach and the first part of the small intestine (duodenum).
- Transmission: Fecal–oral, person-to-person via saliva, contaminated food/water
-
Characteristics:
- Gram-negative
- Spiral-shaped (helical)
- Microaerophilic (needs oxygen at a lower concentration)
- Highly Motile (flagella used for colonization)
- Virulence Factors: - Urease: Neutralizes stomach acid; helps colonization - Flagella: Facilitates movement through gastric mucus - Cytotoxin-Associated Gene A (CagA): Increased cancer risk - Vacuolating Cytotoxin A (VacA): Cell damage - Lipopolysaccharides (LPS): Immune evasion
-
Clinical Manifestations:
- Acute/Chronic Gastritis: Epigastric pain, nausea, bloating
- Peptic Ulcer Disease: Burning pain, nausea, possible bleeding
- Gastric Cancer: Chronic inflammation increases cancer risk (adenocarcinoma)
- Mucosa-Associated Lymphoid Tissue (MALT) lymphoma: Chronic infection stimulates lymphoid tissue.
-
Diagnosis:
- Invasive Methods: Endoscopy, biopsy, rapid urease test, histology, culture.
- Non-Invasive Methods: Urea breath test (detects active infection), stool antigen test.
-
Prevention:
- Good hygiene practices
- Good handwashing
- Clean drinking water
- Safe food handling
- Health education
Vibrio cholerae
- Description: Cholera is an intestinal infection caused by the bacterium Vibrio cholerae.
- Transmission: Contaminated water/food
-
Characteristics:
- Gram-negative
- Comma-shaped (curved rods)
- Facultative anaerobe
- Motile (single flagella)
- Virulence Factors: - Cholera Toxin (CT): Secretion of water and electrolytes - Toxin-Coregulated Pili (TCP): Attachment - Accessory Colonization Factor (ACF): Enhanced intestinal colonization - Zonula Occludens Toxin (Zot): Disrupts intestinal tight junctions - Hemagglutinin Protease (HAP): Facilitates bacterial spread
-
Clinical Manifestations:
- Sever Diarrhea (rice water stool)
- Dehydration & Electrolyte imbalance
- Mild/asymptomatic cases in low infective doses
-
Diagnosis:
- Microscopy (dark-field): Detection of motile, comma-shaped bacteria in stool.
- Culture: Selective media
- Serotyping: Identifying O1 or O139 Antigens
- Molecular Tests: Polymerase Chain Reaction (PCR) to detect toxin genes (ctxA, ctxB)
-
Prevention:
- Hygiene and sanitation (clean water, handwashing)
- Oral Cholera Vaccines (OCVs)
Mycoplasma pneumoniae
- Description: A bacteria that causes respiratory infections, featuring dry cough, fever, and mild shortness of breath
- Transmission: Respiratory droplets (highly contagious)
-
Characteristics:
- Smallest free-living organisms
- Pleomorphic (various shapes)
- Lacks a cell wall
- Resistant to beta-lactam antibiotics
- Aerobic
- Slow growing.
- Pathogenesis: - Uses adhesions protein(P1) to attach to respiratory epithelial cells. - Produces Community-Acquired Respiratory Distress Syndrome (CARDS) toxin, causing inflammation - Strong immune response contributes to symptoms.
-
Clinical Manifestations:
- Dry Cough (hallmark symptom)
- Fever, sore throat, headache, malaise
- Skin Rashes
- Neurological: Meningitis and Encephalitis
- Hematologic: Hemolytic anemia due to cold agglutinins
- Diagnosis: - Culture: Requires specialized media (e.g. Eaton's agar) - Serology: Detection of antibodies against M. pneumoniae - Molecular tests: Detection of M. pneumoniae DNA - Chest X-ray: Used for diagnosis
-
Prevention:
- Good hygiene
- Avoidance of close contact with infected individuals
- Isolation
Chlamydia trachomatis
- Description: Gram-negative bacterium, common cause of sexually transmitted infections (STIs) and eye infections (trachoma).
-
Transmission:
- Sexual contact (vaginal, anal, oral)
- Vertical transmission (mother to newborn)
- Eye contact (trachoma)
- Fomites (rare) / contaminated towels/ surfaces
-
Characteristics:
- Elementary Body (EB): Infective, extracellular form
- Reticulate Body (RB): Non-infective, intracellular form
-
Pathogenesis:
- Infects epithelial cells of urethra, cervix, rectum, and eyes.
- EB enters via endocytosis, transforms into RB, replicates, then matures back into EB, which releases to infect other cells
-
Clinical Manifestations:
-
Urogenital Infections:
- Women: Vaginal discharge, cervicitis, pelvic inflammatory disease (PID), infertility
- Men: Urethritis, epididymitis, prostatitis
- Neonates: Neonatal conjunctivitis, pneumonia
-
Urogenital Infections:
-
Diagnosis:
- Clinical symptoms
- Nucleic acid amplification tests (NAATs): Detecting DNA or RNA in urine/swab samples
- Chlamydia culture
- Serological tests (e.g., DFA, ELISA): Detecting antigens/antibodies
-
Prevention:
- Safe sexual practices (condoms)
- Screening for sexually active individuals
- Partner notification & treatment
- Hygiene practices (in trachoma-endemic areas)
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Description
This lecture provides a detailed overview of bacterial infections, focusing on pathogens like Neisseria gonorrhoeae, Helicobacter pylori, and more. Learn about the characteristics, transmission, and virulence factors of these crucial bacteria. Ideal for medical students and microbiology enthusiasts.
