BIOL 261: CH. 31 - PERSON-TO-PERSON BACTERIAL AND VIRAL DISEASES

Antigenic drift

a minor change in influenza virus antigens due to gene mutation

Antigenic shift

a major change in influenza virus antigen due to gene reassortment between different strains

Cirrhosis

breakdown of normal liver architecture, resulting in fibrosis and compromised liver function

Congenital syphilis

syphilis contracted by an infant from its mother during pregnancy

Fusion inhibitor

a synthetic polypeptide that binds to viral glycoproteins, inhibiting fusion of viral and host cell membranes

Hepatitis

liver inflammation, commonly caused by an infectious agent

Human papillomavirus (HPV)

a sexually transmitted virus that causes genital warts, cervical neoplasia, and cancer

Integrase inhibitor

a drug that interrupts the HIV replication cycle by interfering with integrase, the HIV protein that catalyzes the integration of viral dsDNA into host cell DNA

Meningitis

inflammation of the meninges (brain tissue), sometimes caused by Neisseria meningitidis and characterized by sudden onset of headache, vomiting, and stiff neck, often progressing to coma within hours

Meningococcemia

a rapidly progressing severe disease caused by Neisseria meningitidis and characterized by septicemia, intravascular coagulation, and shock

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Nucleoside reverse transcriptase inhibitor

a nonnucleoside compound that inhibits the action of retroviral reverse transcriptase by binding directly to the catalytic site

Opportunistic pathogen

an organism that causes disease only in the absence of normal host resistance

Pertussis (whooping cough)

a disease caused by a respiratory tract infection with Bordetella pertussis, characterized by a deep, persistent cough

Protease inhibitor

a compound that inhibits the action of viral protease by binding directly to the catalytic site, preventing viral protein processing

Rheumatic fever

an inflammatory autoimmune disease triggered by an immune response to infection by Streptococcus pyogenes

Scarlet fever

the characteristic reddish rash with fever and sore throat resulting from an exotoxin produced by Streptococcus pyogenes

Sexually transmitted infection (STI)

an infection that is usually transmitted by sexual contact

Toxic shock syndrome (TSS)

the acute systemic shock resulting from a host response to an exotoxin produced by Staphylococcus aureus

Tuberculin test

a skin test for previous infection with Mycobacterium tuberculosis

Viral load

a quantitative assessment of the amount of virus in a host organism, usually in the blood

What is important for person-to-person transmission of many infectious diseases?

Aerosols

What is the name of the bacteria that causes walking pneumonia?

Mycoplasma pneumoniae

What type of organism is Mycoplasma pneumoniae?

Bacteria

What key structural feature does Mycoplasma pneumoniae lack?

Cell wall

What illness is commonly associated with Mycoplasma pneumoniae?

Walking pneumonia

What is the Gram reaction and shape of Streptococcus pyogenes?

G+ cocci in chains

Is Streptococcus pyogenes catalase positive or negative?

Catalase negative (no bubbles with H₂O₂)

What does GAS stand for in relation to Streptococcus pyogenes?

Group A strep

What type of hemolysis does Streptococcus pyogenes perform on blood agar?

Beta-hemolysis (completely lyses RBCs)

Is Streptococcus pyogenes sensitive or resistant to bacitracin?

Bacitracin sensitive

What kind of capsule does Streptococcus pyogenes have?

Shiny/slimy capsule

What common illness is caused by Streptococcus pyogenes?

Strep throat

Where does Streptococcus pyogenes grow during strep throat infection?

In the throat

What exotoxin produced by Streptococcus pyogenes contributes to the symptoms of strep throat?

Beta-hemolysins (protein exotoxins)

What is the effect of beta-hemolysins in the throat?

Lyses RBCs → inflammation → swelling → pain

What enzyme produced by Streptococcus pyogenes dissolves clots?

Streptokinase

What bacterium can cause infections of the inner ear, mammary glands, and skin as impetigo?

Streptococcus pyogenes

What is the name of an acute streptococcal skin infection?

Erysipelas

What type of bacterium is associated with streptococcal toxic shock syndrome and scarlet fever?

Streptococcus pyogenes

What carries the exotoxin genes responsible for certain symptoms in group A streptococcal infections?

A lysogenic bacteriophage

What is the role of the lysogenic phage in Streptococcus pyogenes?

Carries genes for the toxin and incorporates into the S. pyogenes chromosome in a latent state

What condition can result from untreated or insufficiently treated S. pyogenes infections?

Rheumatic fever

What causes rheumatic fever following a Streptococcus pyogenes infection?

Molecular mimicry between the streptococci’s M protein and host tissue

How does the immune system contribute to rheumatic fever after a Streptococcus pyogenes infection?

The body makes antibodies against the M protein, but those antibodies also attack heart tissue

What bacterium occasionally causes sudden and severe systemic infections?

Streptococcus pyogenes

What type of infection is cellulitis?

Subcutaneous skin infection

What serious condition is caused by Streptococcus pyogenes and is known as flesh-eating bacteria?

Necrotizing fasciitis

What is the Gram stain and shape arrangement of Streptococcus pneumoniae?

Gram-positive cocci in chains

Is Streptococcus pneumoniae catalase positive or negative?

Catalase negative

What type of hemolysis does Streptococcus pneumoniae exhibit?

Alpha-hemolysis (partial lysis of red blood cells)

What does alpha-hemolysis look like on blood agar?

Green zone

What structural feature helps Streptococcus pneumoniae avoid phagocytosis?

Polysaccharide capsule

What condition is caused by fluid buildup in the lungs due to Streptococcus pneumoniae?

Pneumonia

Is Streptococcus pneumoniae optochin sensitive or resistant?

Optochin sensitive

What is the causative agent of diphtheria?

Corynebacterium diphtheriae

Is Corynebacterium diphtheriae Gram-positive or Gram-negative?

Gram-positive

Does Corynebacterium diphtheriae form spores?

No

What does Corynebacterium diphtheriae look like under the microscope?

Chinese letters

What kind of granules does Corynebacterium diphtheriae have?

Metachromatic granules

What causes the symptoms of diphtheria?

Exotoxin (diphtheria toxin)

What does diphtheria toxin do to throat epithelial cells?

Blocks translation, causing cell death

What forms in the throat as a result of diphtheria toxin?

Pseudomembrane

What can happen if the pseudomembrane is left untreated?

Suffocation

What treatment kills the diphtheria bacteria?

Antibiotics

What treatment blocks the diphtheria toxin?

Antitoxin

How can diphtheria be prevented?

DPT vaccine

What is the causative agent of whooping cough?

Bordetella pertussis

What type of bacterium is Bordetella pertussis?

Gram-negative rod

How can pertussis be identified?

Using a cough plate

What causes tuberculosis?

Mycobacterium tuberculosis

What causes Hansen’s disease (leprosy)?

Mycobacterium leprae

What type of bacteria is Mycobacterium?

Acid-fast, G+ rod

What characteristic does Mycobacterium have in its cell wall?

Mycolic acid (waxy)

What is the result of staining Mycobacterium with a gram stain?

It doesn't stain with gram stain

What do macrophages do in the lower respiratory tract?

They phagocytize.

Where does Mycobacterium grow?

Inside the macrophages.

How is a sputum sample collected?

By coughing from the lower respiratory tract.

What type of agar is used for culturing Mycobacteria?

Lowenstein Jensen agar (blue).

What are the classifications of tuberculosis and leprosy?

Primary infection (initial infection) and postprimary infection (reinfection).

What is the treatment for tuberculosis and leprosy?

Antimicrobial therapy with isoniazid, usually requiring a 9-month regimen.

What type of drug is isoniazid?

A growth factor analog.

How does isoniazid work?

It interferes with mycolic acid synthesis.

What type of bacteria is Mycobacterium leprae?

Acid-fast bacteria.

Where is Mycobacterium leprae more commonly associated with?

Ear lobes and fingers.

What temperature does Mycobacterium leprae prefer to grow in?

Lower temperature.

How is Mycobacterium leprae spread?

Through respiratory droplets and direct contact.

How quickly does Mycobacterium leprae grow?

It grows slowly.

What is meningitis?

Inflammation of the meninges, which cover the brain and spinal cord.

What is the cerebrospinal fluid (CSF) and why is it important in meningitis?

CSF is sterile fluid surrounding the brain and spinal cord, and it is used for diagnosis through a spinal tap.

What are common symptoms of meningitis?

High fever, severe headache, and sensitivity to light.

How is meningitis diagnosed?

Via a spinal tap, where the CSF is tested, and a gram stain is performed.

What is the significance of CSF being sensitive to cold in meningitis?

The CSF must be processed quickly, as it is sensitive to cold, which can affect its results.

What is used for meningitis vaccination?

A vaccine is available to help prevent the disease.

What type of bacteria is Neisseria meningitidis?

It is a Gram-negative cocci, specifically diplococci (two cocci together).

What test results are characteristic of Neisseria meningitidis?

It is oxidase positive and grows on chocolate agar, which is blood agar with lysed RBCs to release hemoglobin.

What causes tissue death in bacterial meningitis?

Exotoxins produced by bacteria.

What type of viral diseases are acute and self-limiting?

Most viral diseases.

What characterizes acute viral infections?

They come on fast and have symptoms like high fever.

What does it mean for a viral infection to be self-limiting?

The body fights it off without the need for medicine.