Exam 4 Lecture 24

• List the airborne bacterial diseases

  Diphtheria, tuberculosis, streptococcal diseases, pertussis, and meningitis
• What bacterium causes tuberculosis

  Mycobaterium tuberculosis
• List features of Mycobacterium tuberculosis and how it spreads

  It gets inhaled

  Phagocytosed by macrophages, survives intracellularly

  Infectious dose is less than 10 cells

  Cell wall mycolic acids act as protection
• How does a host respond to Mycobacterium tuberculosis

  Forms tubercles - bacteria, macrophages, T cells, and proteins

  In tubercles, the bacteria become latent
• What percentage of the world population have latent TB

  25%
• How can Mycobacterium tuberculosis become transmissible when they are in the latent tubercle form

  Tubercles can liquify, causing the bacteria to spread to blood and organs, which allows them to become transmissible

  They can come out of the latent state and can now spread
• Standard method of determining whether a person has had TB or been exposed to M. tuberculosis

  Mantoux Tuberculin Skin Test (TST)
• Describe what occurs during a TB skin test

  Bacterial proteins injected into the forearm

  Immune response (induration) measured in mm (48 to 72 hours)

  Reaction: Delayed hypersensitivity if you have had it

  Antigen presenting macrophages attract and activate sensitized Memory T cells
• Tuberculosis vaccine

  Bacille Calmette-Guerin (BCG) vaccine

  live avirulent M. bovis

  Not generally recommended in the US
• Tuberculosis diagnosis

  Bloody sputum, chest x-ray, acid-fast staining, culture
• TB antimicrobial therapy

  Rifampin and Isoniazid (inhibits mycolic acid synthesis)

  Take it daily for 6-9 months

  Antibiotic resistance is emerging
• What bacterium cause streptococcal diseases

  Streptococcus pyogenes (group A Beta hemolytic - causes complete zones of clearing)

  Streptococcus pneumoniae
• Streptococcal diseases diagnosis, treatment, and prevention

  Diagnosis: Culture and strep test, which uses labeled antibody to detect cell wall carbohydrates

  Treatment: penicillins, erythromycin

  Prevention: Pneumococcal vaccine (Prevnar) polysaccharide based
• Streptococcal virulence factors

  Capsule and M protein promote adherence of bacteria to human host cells

  Antibody to M protein can x-react with heart tissue

  Causing Rheumatic Fever, an autoimmune disease
• Group A streptococci can also cause what

  Invasive infections

  Some strains make tissue destroying protease

  Necrotizing fasciitis ("flesh eating bacteria")
• What bacteria is associated with tooth decay

  Streptococcus mutans

  Part of dental plaque (biofilm)

  Fermentation --> acid --> enamel (decay)
• What bacteria causes Pertussis (whooping cough)

  Bordetella pertussis (gram - )

  Colonizes ciliated cells of respiratory tract

  Stage 1: Cold like symptoms

  Stage 2: Prolonged cough (with inspiratory gasp or whoop)
• Whooping cough virulence factors

  Pili for adherence

  Siderophores acquire iron

  Pertussis toxin - an AB exotoxin
• Pertussis vaccination and treatment

  Subunit vaccine DTP

  - DT are toxoids

  - P is the killed bacteria

  
  

  Currently is DTaP

  - DT are toxoids

  - aP is acellular, toxoid and other protein antigens

  
  

  Tdap booster
• Inflammation of the brain, spinal cord meninges (membranes)

  Meningitis
• What is one bacteria that causes meningitis

  Neisseria meningitidis
• List Neisseria meningitidis features

  Leading cause of meningococcal disease in children and young adults

  Spread person to person, respiratory, or throat secretions

  Can cross mucosal barrier into blood

  Serogroups - groups of strains with common surface antigens (A,B,C,Y,W)

  Virulence factors: pili, capsules, endotoxin
• Meningitis symptoms prevention diagnosis and treatment

  Symptoms: sore throat, vomiting, confusion, stiff neck, rash

  Prevention:

  - MCV4 vaccine based on capsular polysaccharide; protects against A, C, Y, and W

  - Bexsero vaccine is based on group B outer membrane protein

  Diagnosis: gram stain spinal fluid, culture bacterium

  
  

  Meningitis is gram - diplococcus

  
  

  Treatment: antibiotics (cell wall, protein synthesis inhibitors)
• What differentiates between meningitis and flu symptoms

  A rash
• List arthropod-borne bacterial diseases

  Plague and Lyme disease
• What bacteria causes the plague

  Yersinia pestis (Gram - )

  Injects toxic proteins into human cells

  2 forms:

  Bubonic - flea

  Pneumonic (person to person) - flu-like, fatal if not treated early, category A bioweapons agent
• Enlarged lymph node

  buboe
• Many gram - pathogens use what system to inject effector proteins

  Type 3 Secretion system
• What structure makes up the type 3 secretion system and what are the three parts

  Injectisome

  - basal body

  - needle

  - pore
• What do the effector proteins target once they are injected

  Cytoskeleton and signaling (NFkB)
• Yersinia injects effectors into human cells including what

  Macrophages

  Block cytoskeletal rearrangements
• What is the most commonly reported tick-borne disease in the US

  Lyme diseases
• What bacteria causes Lyme disease

  Borrelia burgdorferi (spirochete)
• What is the vector for Lyme disease

  Blacklegged (deer) tick
• Stages of Lyme disease

  Localized (7-10 days) - bulls eye rash (erythema migrans), flu like symptoms, most treatable with doxycycline (tetracycline) and penicillins

  
  

  Disseminated (weeks or months) - muscle pain, arthritis, antibody to Borrelia proteins, may X-react with human MHC

  
  

  Late (years) - nervous system involvement
• List direct contact bacterial diseases

  Anthrax and staphylococcal diseases
• What bacteria causes anthrax

  Bacillus anthracis
• Virulence factors of anthrax

  Capsule and anthrax toxin, which targets macrophages and causes cell death

  Toxin and capsule genes encoded on separate plasmids
• Forms of Anthrax

  Cutaneous - cut, abrasion

  Pulmonary - spores inhaled

  - spores enter macrophages in lungs and germinate and produce toxin

  - the toxin then kills the macrophages and other cells

  - treatment with Ciprofloxacin
• Two major species of staphylococcal diseases

  S. aureus - invasive, virulent

  S. epidermidis - less invasive, less virulent