Microbiology Study Guide: Chapters 21-27
Chapter 21: Respiratory System Infections
Bacterial Infections
Streptococcus pyogenes
Q: What is the causative agent for strep throat?
A: Streptococcus pyogenes
Influenza Virus
Q: Projecting from the outer envelope of the influenza virus are two glycoproteins called:
A: Hemagglutinin and neuraminidase.
Common Cold
Q: A vaccine for the common cold is not feasible because:
A: There are more than 100 types of rhinovirus.
Coccidioidomycosis and Histoplasmosis
Q: Which is/are true of coccidioidomycosis and histoplasmosis? What is coccidioidomycosis?
A:
- They are both soil fungi.
- They are both dimorphic fungi.
Coccidioidomycosis: A lung mycosis, also known as valley fever, treatable by antibiotics.
Tuberculosis (TB)
Q: Why is the TB bacillus resistant?
A: It has an unusual cell wall with complex glycolipids called mycolic acids.
Chapter 22: Skin and Eye Infections
Acne
Q: What causes acne?
A: Propionibacterium acnes.
Skin Bacteria and Environment
Q: Would a person living in the tropics or in the desert have larger numbers of bacteria living on the surface of their skin?
A: People in the tropics would have more bacteria living on their skin surface due to the higher humidity, which provides a more favorable environment for bacterial growth compared to the dry desert conditions.
Staphylococcus aureus
Q: The virulence factor for Staphylococcus aureus that causes scalded skin syndrome is:
A: Exfoliatin toxin.
Streptococcus pyogenes
Q: What is the virulence factor in Streptococcus pyogenes that helps it to evade phagocytosis?
A: A hyaluronic acid capsule and a cell wall component called M protein.
Chickenpox and Shingles
Q: What is the causative agent for chickenpox? What does it cause when reactivated?
A:
- Chickenpox is caused by the varicella-zoster virus (VZV).
- When reactivated, it causes shingles.
Chapter 23: Wound Infections
Necrotizing Fasciitis
Q: What is the name of the flesh-eating microorganism?
A: Necrotizing fasciitis, a rare but serious complication of S. pyogenes infection.
Pseudomonas aeruginosa
Q: What is the name of the gram-negative bacteria that grows in disinfectants?
A: Pseudomonas aeruginosa
Tetanus
Q: What is the mode of action for tetanospasmin?
A: Tetanospasmin, produced by Clostridium tetani, inhibits the release of gamma-aminobutyric acid (GABA), causing spastic paralysis by preventing muscle relaxation.
Abscess
Q: Define abscess.
A: An abscess is a localized collection of pus, which contains leukocytes, tissue breakdown products, and infecting organisms. Abscess formation helps prevent the spread of infection within tissue.
Gas Gangrene
Q: What is the effective treatment for gas gangrene?
A: Debridement of dead tissue.
Chapter 24: Digestive System Infections
Dental Caries
Q: How is dental caries produced?
A: Dental caries, also known as tooth decay, is caused by Streptococcus mutans. When tooth enamel is damaged, microorganisms can enter the tooth and cause decay.
Peptic Ulcer
Q: How does H. pylori cause peptic ulcers?
A: H. pylori produces urease, which breaks down urea and carbon dioxide into ammonia. The ammonia neutralizes stomach acid, allowing the bacteria to survive and cause inflammation and damage to the stomach lining, leading to peptic ulcers.
Diarrheal Diseases
Q: What are the strains of E. coli that cause diarrhea?
A:
- STEC
- ETEC
- EIEC
- EPEC
- EAEC
- DAEC
Typhoid Fever
Q: Typhoid bacillus is maintained in which organ?
A: Gallbladder (Typhoid Mary’s organ)
Treatment for Diarrheal Diseases
Q: What is the primary treatment for diarrheal diseases?
A: Oral rehydration therapy
Chapter 25: Cardiovascular and Systemic Infections
Subacute Bacterial Endocarditis (SBE)
Q: How do bacteria that cause SBE gain access to the bloodstream?
A: Dental procedures can introduce bacteria into the bloodstream, leading to SBE.
Epstein-Barr Virus (EBV)
Q: Epstein-Barr virus (EBV), which causes mono, becomes latent in which cell?
A: B-cells
Bacteremia vs. Septicemia
Q: What is the difference between bacteremia and septicemia?
A:
- Bacteremia: Presence of bacteria in the blood.
- Septicemia: A systemic infection caused by the presence of bacteria and their toxins in the blood.
Septic Shock
Q: Which group of bacteria causes fatal septic shock?
A: Gram-negative bacteria
Chapter 26: Nervous System Infections
Meningitis
Q: What is meningitis?
A: Inflammation of the meninges, the membranes covering the brain and spinal cord.
Bacterial Meningitis
Q: What is the causative agent for bacterial meningitis?
A:
- Streptococcus pneumoniae
- Neisseria meningitidis
- Haemophilus influenzae
Meningococcus
Q: What is the virulence factor of meningococcus?
A: Neisseria meningitidis uses pili for attachment.
Listeriosis
Q: What is the causative agent, pathogenesis, and epidemiology of listeriosis?
A: Listeriosis is a foodborne illness caused by Listeria monocytogenes, which can lead to meningitis. It is often asymptomatic in healthy people but can be severe in pregnant women and immunocompromised individuals. Listeria can grow at refrigerating temperatures.
Leprosy
Q: What is the causative agent for leprosy? What is another name for this disease?
A:
- Mycobacterium leprae
- Hansen’s disease
Prions
Q: What are prions?
A: Proteinaceous infectious particles
Q: Name a disease caused by prions.
A: Transmissible spongiform encephalopathies (TSEs)
Infant Botulism
Q: Why should honey not be fed to infants?
A: Honey can contain endospores of Clostridium botulinum, which can cause infant botulism in babies with underdeveloped immune systems.
Rabies
Q: What is the mode of transmission for rabies?
A: Rabies is transmitted through infected animal saliva, typically via bite wounds. The virus travels from the wound to the central nervous system, causing a fatal infection.
Chapter 27: Urogenital Infections
Urinary Tract Infections (UTIs)
Q: How do you get a UTI?
A: E. coli commonly enters the bladder by ascending the urethra.
UTIs and STDs
Q: Is a UTI a sexually transmitted disease?
A: No
Gonorrhea
Q: What are the complications of untreated gonorrhea?
A:
- Sterility
- Urinary tract infections
- Prostatic abscesses
- Orchitis
- Pelvic inflammatory disease (in women)
Syphilis
Q: What are the characteristic signs of primary, secondary, and tertiary syphilis?
A:
- Primary: Chancre (a painless sore)
- Secondary: Flu-like symptoms (runny nose, watery eyes, aches/pains, sore throat), rash, lesions
- Tertiary: Gumma (soft, painless, granular lesion), damage to major blood vessels, spinal cord, and meninges (leading to insanity)
Herpes
Q: Herpes virus remains latent in which cell?
A: Nerve cells
Human Papillomavirus (HPV)
Q: Which virus causes cervical cancer?
A: HPV
HIV
Q: What are the antiretroviral treatments for HIV?
A: Antiretroviral drugs block the replication of HIV but do not affect viral nucleic acid already integrated into the host cell genome.