Transcript Welcome to Ms. Looney`s Biology Class

Jumpstart 3/22/2010
Create a Venn diagram comparing and
contrasting Staphylococcus aureus and
Streptococcus pyogenes.
Corynebacterium and
Mycobacterium
Corynebacterium
• The basics:
– Gram positive rods in clumps or short chains
– Non-spore forming
– High guanine-cytosine content
– Some species are commonly found on the
skin, respiratory tract, GI tract, and urogentital
tract
• Can cause opportunistic infections
– Some are commonly associated with disease
Corynebacterium diptheriae
• Toxins
– Exotoxin secreted by bacteria causes the
effects observed
• Diptheria toxin and A-B exotoxin
– Damages the heart, kidneys, and nervous system
Diphtheria
• C. diphtheria causes a disease called diphtheria
(shocking, I know)
• Found worldwide
– Higher incidences in poor, crowded urban areas
– Last big outbreak was in Soviet union in 1994 where it
caused 1746 deaths.
• Transmitted by respiratory droplets or by
touching a person who has it.
• Humans are the only known reservoir
Diphtheria
• Uncommon in the US, because
immunization is required for school
children (DPT vaccine)
– 200000 cases in 1921 vs. 5 cases since 1980
• Different forms of diphtheria
– Respiratory
– Cutaneous
Respiratory Diphtheria
• 2-6 day incubation period.
• Organisms multiply in pharynx, damaging
those cells
– Sore throat, malaise, low-grade fever
– Thick exudate is produced that is tough to
dislodge without causing the underlying tissue
to bleed
• Infection lasts about 1 week, the thick
exudate breaks up and is expectorated
Respiratory Diphtheria
• Bull neck
Cutaneous diphtheria
• Acquired through skin contact with an
infected person
• Has to enter body through a break in the
skin
• Papule develops first, can turn into a nonhealing ulcer. Systemic signs can occur
due to exotoxin effects.
Cutaneous diphtheria
Diagnosis and Treatment
• Must be clinically diagnosed because lab
tests could take at least a week
• Treatment is early administration of
antitoxin. Once toxin enters the cells of
the body, death is certain.
Treatment
• Penicillin or erythromycin is used to kill C.
diptheriae and stop it from producing toxin.
• Bed rest, isolation
• If you are going to be around infected
people, booster within 5 yrs is required.
Diphtheria Guided Reading
1.
Summarize the outbreak of diphtheria in Nome, Alaska
in 1925.
2.
What factors caused the first recorded epidemic of
diphtheria?
3.
When were routine immunizations for diphtheria
introduced? What has happened since then?
4.
Why might there be a “reemergence” of diphtheria?
5.
Pretend that you are a Red Cross worker in the 1920s.
On a half sheet of white paper, create an ad that
explains diphtheria and the importance of routine
vaccination of children.
Jumpstart 3/26/2010
• What is the causative agent of diphtheria?
• List signs, symptoms, and treatment for
the disease.
• How can diphtheria be prevented (name 3
ways).
Mycobacterium
• The basics:
– Non-motile
– Non-spore forming
– Aerobic rods
– Do not Gram stain...do you remember
why?
• Cell wall is waxy….have to use an “acid-fast” stain
Importance of that cell wall in
mycobacteria
• Because their cell wall is so complex,
– They have slow growth
– They are resistant to detergents
– They are resistant to a lot of antibiotics
• The one mycobacterium we are going to
talk about is Mycobacterium tuberculosis
Mycobacterium tuberculosis
• Intracellular pathogen capable of causing
lifelong infections.
• A lot about this bacterium and how it
causes disease is still unknown.
M. tuberculosis…what we do know:
• Enters the respiratory tract and passes through
the alveoli where is phagocytized by
macrophages.
• Lysosomes are unable to break it down, so it just
exists inside of the macrophage (called a
phagosome) and now has access to nutrients for
replication.
• These bacteria can then kill cells and tissues,
forming granulomas. (these become dormant
and encapsulated and can later break off and
spread).
Epidemiology
• Humans are the only natural reservoir
– Primates and other animals can become
infected in the laboratory, but not naturally
• Spread by close person-to-person contact
through inhalation of respiratory droplets
• In 2002, it was estimated by the WHO that
a third of the world’s population was
infected by M. tuberculosis
• In the U.S., incidence is lower than in most
places… about 15000 cases per year are
reported (more than half being foreignborn)
Tuberculosis
• Can involve any organ, but most common
place you see it is in the lungs.
• The likelihood that exposure to the
pathogen will lead to active disease is only
about 10-15 %.
• Malaise, coughs, weight loss, night sweats
• Sputum will be bloody and purulent
• Tissue destruction can occur
Diagnosis
• Diagnosis is in 3 parts:
– Positive Skin test reactivity
– Radiographic evidence of pulmonary disease
– Laboratory detection of Mycobacteria
Treatment
• Antibiotic treatment: Streptomycin
• Unfortunately, M. tuberculosis is showing
resistance
• Usually a combination of several
antibiotics taken over a long period of time
Case Study page 309
• Complete questions 1, 2, 3, and 5 (skip
question 4.
Jumpstart 3/29
1. What does the microbe M. tuberculosis
do to the human body in an active
infection?
2. Describe how you would positively
diagnose a patient you suspect might
have TB?
TB Reading
1. What is the causative agent of TB?
2. How is TB transmitted?
3. Describe the course of infection of
tuberculosis (be specific)
4. Describe the impact of industrialization
on TB.
5. Describe the WHOs strategy for ridding
the world of TB.