Microbiology exam 3 review

BIOL2320:FALL 2025 Wright

Unit III Review

Chapter 15 Adaptive Immunity:

1. Characteristics:

· Memory

· Specific

· Antibody Immunity (B-cells)

· Cellular Immunity (T-cells)

2. Antigen: molecule from pathogen that reacts with antibodies. Examples:

· Capsule

· Cell wall

· Fimbriae

· Flagella

· Pili

· toxins

3. Antibody: protein of the Immune System that binds to antigen. Part of Adaptive Immunity.

4. Epitope: the part of the antigen that binds the antibody.

5. Primary and secondary immune antibody production graph

6. Antibody structure: Antibodies have a variable region and a constant region. Variable region binds to the antigen.

7. Antibodies (Immunoglobulins):

a) IgG: most abundant; can cross placenta and tissues; opsonizes, agglutinate, neutralize (viruses, bacteria).

b) IgA: common in secretions; breast milk, tears, saliva. Neutralize, trap pathogens in mucus.

c) IgE: low concentration in blood; functions against parasites and allergies, stimulate inflammation, activate Basophils and Mast Cells (Granulocytes) which release histamine.

d) IgM: pentamer; first antibody produced; functions to opsonize, agglutinate, neutralize

e) IgD: found in membrane of B cells (bind antigen).

8. Functions of antibodies against pathogens:

· Neutralize pathogens

· Opsonize (coats) for phagocytosis

· Agglutinate (aggregate)

· Activate complement

· Cell-mediated cytotoxicity

9. Natural Killer cells:

o Kill pathogens that are too big

o Have Fc receptor that binds constant region of Antibody that is attached to a pathogen

o Release perforin and granzyme (cytotoxins)

10. Antigen-Presenting Cells

v Dendritic cells, Macrophages, B cells

v Eat bacteria (phagocytosis)

v Present antigen on MHII (Major Histocompatibility Complex II), which is needed to activate T-helper cells.

11. T-cell Immunity:

v Antibodies fight pathogens in extracellular spaces.

v T-Cytotoxic lymphocyte cell targets intracellular pathogens

v T-Cytotoxic lymphocyte responsible for the cell-mediated immune response

12. T-cells mature in thymus

B-cells mature in the bone marrow

13. Helper T-cells:

• Activate Antibody immunity

• Activate T-cytotoxic-cell mediated immunity

• Enhance killing by Macrophages and NK cells

14. Regulatory T-cells: protect against autoimmune diseases

15. Cytotoxic T-cells: recognize, target, and kill infected cells

16. Helper T-cells:

a. TH1

• Activate cytokines

• Stimulate Cytotoxic T cells

• Stimulate Macrophages, Natural Killer cells

• Short lived

b. TH2

• Activate (through cytokines) B cells –B cell clone plasma cell to release/produce antibodies

• Short-lived

c. T-helper Memory cell

• Lives long

• Remembers antigen

• Mount Secondary Immune Response

Chapter 16: Immune Diseases:

1. Allergic Reaction: Immune response to allergen (an antigen but not from pathogen).

2. Anaphylaxis: Severe allergic reaction

• Blood pressure drops

• Swelling

• Throat closes

• Treated with epinephrine

3. Type I Hypersensitivity:

• Response to allergen

• Activates IgE

• Treated with antihistamine/steroids

4. Type II Hypersensitivity:

• Blood Transfusion (Hemolytic transfusion)

• Hemolytic disease of the newborn

• Transplant rejection

5. Type III Hypersensitivity:

• IgG/IgM antibodies form large immune complexes

• Leads to tissue damage (ex. Kidney)

• Neutrophils destroy tissues with enzymes trying to destroy complex

• Activates coagulation  blood clots  Ischemia (low blood supply to tissue)  necrosis (dead tissue)

6. Type IV Hypersensitivity:

• Contact dermatitis

• Activated by TH1

• T-cells/Macrophages involved

• Asthma

Autoimmune disorders:

1. Celiac: immune reaction to gluten, damages lining of the small intestine leading to inflammation,

malabsorption and diarrhea.

2. Graves disease: Hyperthyroid (overactive thyroid); increases Thyroid-stimulating hormone; Symptoms:

• Bulging eyes

• Heat intolerance

• Rapid heart rate

• Anxiety/Irritability

• Fatigue

• Enlarged thyroid (goiter)

5. Multiple Sclerosis: Immune system attacks and damages myelin sheath of the nerve fibers.

Symptoms:

• Inflammation

• Muscle weakness

• Unsteady balance/gait

• Blurry/double vision

• Numbness/tingling sensations

• Fatigue

• Cognitive issues

6. Myasthenia Gravis: Antibodies attack Acetylcholine Receptors and block Acetylcholine at

Neuromuscular junction. Symptoms:

• Decreases muscle contraction

• Extreme muscle weakness

• Affects speech, walking, talking, chewing, respiration (breathing)

7. Rheumatoid arthritis (RA): Chronic inflammation caused by release of inflammatory cytokines.

RA affects the lining of the joints, causing painful swelling that over many years can lead to bone

erosion and joint deformity. RA can damage many parts of the body, including the skin, eyes, lungs,

heart, and blood vessels. RA signs and symptoms vary in severity and may come and go. Periods of

increased disease activity (flares), alternate with periods of remission (swelling and pain disappear).

Swollen, tender joints
Stiff Joints
Fatigue, fever and loss of appetite

8. Lupus: Immune System antibodies attack many types of tissues, including the joints, skin, kidneys,

blood cells, brain, heart and lungs. Difficult to diagnose because symptoms similar to other conditions.

Fatigue
Fever
Joint pain, stiffness and swelling
Butterfly-shaped rash on the face
Skin lesions that worsen with sun exposure
Fingers and toes may turn white/blue when exposed to cold or during stressful periods
Shortness of breath
Chest pain
Dry eyes
Headaches, confusion and memory loss

Skin and Eye Infections

A. Bacterial Infections:

1. Skin: physical barrier, prevent infections, also

• Sweat (has salts, lysozyme, antimicrobial peptides)

• Sebum (oil that feed commensal bacteria)

• Microbiota (commensal bacteria that outcompetes pathogens)

2. Skin infections: many caused by opportunistic microbes (most common: S. aureus, Staph epi,

Streptococcus). Staph aureus distinguished from Strep infections because S. aureus is catalase positive.

Staph skin infections:

Ø Folliculitis: bumps and pimples that may be itchy, red, may contain pus

Ø Furuncles :(boils)

Ø Carbuncles: (deeper abscesses)

3. Tears have:

• Lysozyme(destroy bacterial cell wall)

• Defensins (antimicrobial)

• Lactoferrin( binds iron some bacteria need to grow)

• Mucin (hydrates eye)

4. Conjunctivitis: infection of the conjunctiva (pink eye) The most common cause of bacterial conjunctivitis is Staphylococcus aureus, The most common cause of viral conjunctivitis is the adenovirus

5. Staphylococcal scalded skin syndrome (SSSS)

superficial infection caused by S. aureus that is most commonly seen in young children, especially infants. Bacterial exotoxins first produce erythema (redness of the skin) and then severe peeling of the skin due to detachment of the upper layers of skin.

6. Ocular Trachoma is a Chronic Infection of the Eye Caused by Chlamydia trachomatis

major cause of blindness around the world. Endemic in parts of Africa, Asia, the Middle East, Latin America, and Pacific Islands.

7. MRSA (Methicillin-Resistant Staph Aureus): Opportunistic and very contagious infection. Strain is

resistant to many antibiotics. Prevalent in health-care settings (hospitals, nursing homes) and it's

known as health care-associated (HA-MRSA).

HA-MRSA infections are associated with invasive surgical procedures or devices, such intravenous tubing or artificial joints. HA-MRSA can also spread by healthcare workers.

Another type is community-associated (CA-MRSA), often starts as a painful skin boil. CA-MRSA usually

spreads by skin-to-skin contact. More common in athletes and people who live in crowded conditions

(military).

8. Streptococcus pyogenes bacteria: have many virulence factors that help establish an infection:

• Streptolysins tissue damage

• Hyaluronidase

• Streptokinase – dissolve blood clots

• M-protein

• Capsule Prevent Phagocytosis

9. Skin Streptococcus infections:

• Cellulitis: painful, red rash on skin

• Erysipelas: large very inflamed patch of the dermis causes raised rash with clear borders

• Erythema nodosum: inflammation in the fat cells of the hypodermis; characterized by red lumps or nodules, usually on the lower legs

10. Necrotizing Fasciitis: Streptococcus pyogenes infection that start in the skin and spread.

v Rare, potentially life-threatening condition

v sometimes referred to as flesh-eating bacterial syndrome

v Virulence factors:

· Invasins: allow bacteria to attach to tissues

· Proteases: enzymes that destroy tissue and inactivate complement

v Treatment: debridement (surgical removal of dead or infected tissue) or amputation to stop the spread of the infection and intravenous antibiotics

v Other organisms that can cause it: Klebsiella, Clostridium, E. coli, S. aureus

11. Pseudomonas aeruginosa, a gram-negative aerobic bacillus common in water, soil and human skin.

Common cause of opportunistic infections of wounds and burns
Can cause hot tub folliculitis, in users of pools and hot tubs
Cause of otitis externa, an infection of the ear canal that causes itching, redness, and discomfort, and can progress to fever, pain, and swelling

12. Propionibacterium acnes: feed on sebum; secrete enzyme that damage hair follicle and cause lesions

Comedones (pimples)

13. Anthrax: Zoonotic infection caused by Bacillus anthracis

• B. anthracis, a gram-positive, spore-forming, facultative anaerobe

• Anthrax mainly affects animals such as sheep, goats, cattle, and deer, but can affect humans as well.

• the spores are found in soil and survive for years

• Most anthrax cases occur when spores enter the body through cuts in the skin (cutaneous anthrax) black eschar

B. Viral infections:

14. Papilloma (warts) are common skin infections caused by human papillomavirus (HPV) and are

transmitted by direct contact.

• There are many types of HPV: common warts, plantar warts, flat warts, and filiform warts (long).

• HPV can also cause sexually transmitted genital warts. HPV major cause of cervical cancer.

• Vaccine for some strains of HPV

15. Herpes (skin and eye). Two types: HSV-1 and HSV-2.

Ø HSV-1 is transmitted by direct contact and is associated with oral herpes.

Ø HSV-2 is usually transmitted sexually and is associated with genital herpes.

Ø incidence of genital HSV-1 and oral HSV-2 infections has been decreasing in recent years.

16. Roseola: mild viral disease caused by Herpes 6. More common in children. Resolves on its own. Symptoms: Fever, runny nose, sore throat, rash on chest and abdomen.

17. Fifth disease: caused by Parvovirus; very contagious; most common in children; symptoms similar to a cold; acquired through respiratory droplets, can cause rash in face and body; resolves on its own.

18. Varicella Zoster Virus (VZV) Causes Chickenpox and Shingles

• Reactivation of latent HHV-3 after a chickenpox infection

• Presents with asymmetrical lesions on the trunk or head

• Develops after stress, X-ray treatments, immunosuppressive drugs, surgery, or developing malignancy

• Attenuated vaccine recommended for adults

19. Variola Virus Causes Smallpox

Naturally occurring smallpox has been eliminated but it is considered a bioterrorism threat

Begins with fever and vomiting

Ulcers on mouth, tongue, throat

Skin Rash

• Macular (flat bump)

• Papular (small, elevated solid bump)

• Vesicular (elevated with clear fluid)

• Pustular (elevated with pus)

20. Coxsackievirus (an Enterovirus) Causes Hand, Foot, and Mouth Disease (HFMD)

Most common in babies and children under age 5

Fever, sore throat, malaise

Painful blisters inside the mouth

Red or blister-like spots on palms of hands and soles of feet and often genitals, buttocks, knees, and elbows

21. Measles, Also Known as Rubeola, is Caused by the Measles Virus

• Sore throat, dry cough, headache, conjunctivitis, and fever

• Koplik’s spots appear as a prelude to the characteristic red, maculopapular rash

• Most serious complication of measles is subacute sclerosing panencephalitis

22.Rubella, Also Known as the German Measles, is Caused by Rubella Virus

Causes a relatively minor rash with few complications

Serious damage can occur when a fetus is exposed in the womb

Congenital defects caused by rubella:

• Deafness

• Cardiac abnormalities

• Ocular lesions

• Rashes

• Intellectual and physical impairments

23. Fungal infections (mycoses):

• Cutaneous mycoses (superficial infections of the epidermis, hair, and nails)

• Subcutaneous mycoses (penetrate the epidermis and dermis)

• Systemic mycoses (spread throughout body)

24. Tineas: fungal infection of the skin.

Ø Cutaneous mycoses caused by dermatophytes, fungi that feed on keratin (protein in skin, hair, and nails.

Ø Tineas are generally called ringworm, but tineas in specific locations have distinctive names:

• Tinea corporis (ringworm) Body

• Tinea capitis (ringworm) Scalp

• Tinea pedis (athlete’s foot) Feet

• Tinea barbae (barber’s itch) Beard

• Tinea cruris (jock itch) Groin

Respiratory Infections:

1. Defenses of the Respiratory System:

· Goblet cells (Acidity and viscosity inhibit microbes )

· Ciliated epithelial cells (cilia remove microbes trapped in mucus)

· Mucosal Associated Lymphoid Tissue (MALT; release IgA, Lysozyme, surfactant, antimicrobial defensins)

· Alveolar macrophages

2. Respiratory System Microbiota (Opportunistic Pathogens)

• Streptococcus

• Corynebacterium

• Haemophilus

• Candida

3. Streptococcal pharyngitis (strep throat)

Common upper respiratory infection.
Caused by Streptococcus pyogenes (group A strep).
mucosal membranes damaged by the S. pyogenes exoenzymes and exotoxins.
can degrade connective tissues with hyaluronidase, collagenase and streptokinase.
Streptolysins that can destroy red and white blood cells.
The classic signs of streptococcal pharyngitis: fever higher than 100.4 °F.

4. Acute otitis media:

· Infection of the middle ear

· common between 3 months and 3 years.

· pus accumulates in the middle ear.

· As pus builds up, the tympanic membrane bulges leading to ear pain.

· Inflammation leads to swelling of eustachian tubes, may lead to fever, nausea, vomiting, and diarrhea in infants.

5. Diphtheria: respiratory infection of the oropharynx

· The causative agent is Corynebacterium diphtheriae.

· Diphtheria are part of nasopharyngeal microbiota.

· pathogenic because of the diphtheria toxin.

· transmitted by coughing.

· The toxin’s leads to the death of cell tissue and an inflammatory response.

· An exudate of dead cells, pus, red blood cells, fibrin, and bacteria forms a pseudomembrane.

· Enlarged membrane can cause suffocation.

6. Bacterial Pneumonia:

• Pneumonia is a general term for infections of the lungs.

• Infection leads to inflammation and accumulation of fluids and white blood cells in the alveoli.

• Pneumonia caused by bacteria, viruses, fungi, and other organisms.

• Most pneumonias are bacterial in origin.

7. Haemophilus Pneumonia:

small coccobacillus found in the pharynx of most healthy children.
Haemophilus pneumonia affects mainly the elderly.
H. influenzae is spread by coughing.

8. Health Care-Associated Pneumonia:

· Caused by opportunistic bacteria such as Klebsiella pneumoniae, Staph aureus.

· Risk patients: elderly, persons with preexisting lung conditions, and the immunocompromised.

· Patients receiving intubation, antibiotics, and immune suppressing drugs at risk because disruption of the mucocilia and other pulmonary defenses.

· Medical devices such as catheters, implants, and ventilators can introduce opportunistic pathogens into the body.

· Pneumonia caused by K. pneumoniae is characterized by lung necrosis and sputum

· The sputum is made of clumps of blood, mucus, and debris from the thick polysaccharide capsule produced by the bacterium.

· K. pneumoniae is often multidrug resistant and can be fatal.

9. Tuberculosis:

· After inhalation, the bacteria enter the lung alveoli.

· The cells are phagocytized by macrophages; survive and multiply within phagocytes (protected by the mycolic acid in cell walls).

· it creates an inflammatory response; neutrophils and macrophages accumulate.

· Several months pass before an immunological response is mounted by T cells and B cells.

· The lesions in the alveoli form small round lesions called tubercles.

10. Viral Infections: Common cold

· Mild viral infections of the nasal cavity.

· More than 200 different viruses cause the common cold.

· Most common viruses: rhinoviruses, coronaviruses, and adenoviruses.

· These viruses commonly found in the human population; transmitted through direct contact, coughing and sneezing.

· Rhinoviruses persist on surfaces for up to a week.

· Rhinoviruses replicate best between 91.4 °F and 95 °F, below normal body temperature (98.6 °F) and tend to infect the cooler tissues of the nasal cavities.

· The absence of high fever is typically used to differentiate common colds from flu.

· The disease is self-limiting and resolves within 1–2 weeks.

· There are no effective antiviral treatments for the common cold and antibacterial drugs should not be prescribed.

· Because of the large number of viruses that cause colds, we don’t develop immunity to all cold viruses.

11. Flu (Influenza):

· Commonly known as the flu, influenza is viral disease caused by orthomyxovirus.

· primarily affects the upper respiratory tract but can extend to the lower respiratory tract.

· Prevalent worldwide and causes up to 50,000 deaths each year in the US.

· The annual mortality rate can vary greatly depending on the virulence of the strains responsible for seasonal epidemics.

· Influenza infections are characterized by fever, chills, and body aches.

Urogenital System Infections:

1. Urogenital System Infections:

· Microbes from outside

· Normal microbiota (opportunistic)

2. Normal Microbiota of the Urogenital System in women protect against UTI:

· Estrogen increases secretion of glycogen (promote Lactobacillus growth)

· Lactobacillus bacteria produces lactic acid making environment acidic

· Lactobacillus secrete peroxide and antibacterial bacteriocins

3. Signs and Symptoms of Urogenital Infections:

· Cystitis: inflammation of the bladder

· Urethritis: inflammation of the urethra

· Pyelonephritis: inflammation of the kidney

· Pyelonephritis: acute inflammation of the kidney

a) by bacteria from other parts of the urinary tract

b) fecal bacteria such as E. coli is usually the cause

c) Symptoms: back pain, fever, and nausea or vomiting

· Glomerulonephritis: acute or chronic inflammation and damage to kidney glomeruli

a) immune complexes form in blood by S. pyogenes antigens and antibodies; these complexes lodge in the glomeruli and trigger an inflammation

4. Nongonococcal Urethritis (NGU):

· Often asymptomatic

· Commonly caused by Chlamydia trachomatis

· Chlamydia: the most reported STI in the US.

5. Gonorrhea: Common sexually transmitted disease (STI)

· Caused by Neisseria gonorrhoeae (gonococcus)

· fimbriae help bacteria attach to tissues and LPS endotoxin enhances its pathogenicity

· N. gonorrhoeae can infect other tissues including skin, meninges, pharynx, and conjunctiva

· Many infected individuals are asymptomatic carriers

· Men can have pain, burning during urination and discharge

· Women can have pelvic pain, discharge, bleeding, and pain/irritation during urination

6. Syphilis: STI caused by spirochete Treponema pallidum

· Primary: forms painless chancre (painless ulcer)

· Secondary: Rash on skin or mucous membranes; fever, lymph swelling; highly contagious phase

· Tertiary: forms years after infection; lesions anywhere in body; causes cardiovascular syphilis and neurosyphilis

7. Congenital Syphilis:

· passed by mother to fetus

· Infection may lead to miscarriage or stillbirth

· Children show symptoms of secondary syphilis and infection can deform the nose

· Can cause tissue damage to organs and teeth

· Other complications: osteochondritis, anemia, blindness, bone deformations, neurosyphilis, and cardiovascular lesions

· Expecting mothers screened for syphilis in first trimester of pregnancy