Download I - UAB School of Optometry

FUN2: 10:00-11:00
Scribe: Brannon Heape
Wednesday, November 5, 2008
Proof: Ryan O’Neill
Dr. Waites
Gram Positive Bacteria/Neisseria & Chlamydia
Page 1 of 3
Finishing Gram Positive Bacteria Lecture
I. Listeria monocytogenes [S32]:
a. It is a gram-positive bacteria that is a coccobaccillus.
i. Bacteria come in different shapes - morphology.
1. Cocci: Staph and Strep
2. Rod: Bacillus
3. Coccobacillus: more “oval” or “egg” shaped.
b. Catalase positive and weakly β-hemolytic (notice picture).
c. They are facultative bacteria, meaning they can live inside or outside of cells.
d. They are very motile organisms (this is key in identifying them).
e. They have a number of things that help them attach to host cells.
i. Hemolysins and Phospholipases are examples of this.
f. Diseases associated with this bacteria can be:
i. Foodborne (dairy products): Listeria can survive at low temperatures. A study a couple years ago with milk
showed that this organism can survive at cold temperatures for long periods of time.
ii. Menigitis and Neonatal Infections occasionally
iii. This isn’t a very common disease-causing bacteria but it can occur and we need to be familiar with it.
II. Key Points [S33]:
a. Motility Test: take a semisolid medium and you take a needle with your bacteria on it and dip it into the test tube.
If your bacterium is motile it will spread out.
i. In the case of Listeria monocytogenes it will form an “umbrella shape”.
b. So L. monocytogenes is gram positive coccobaccilli, catalase postitive, motile, esculin positive, and β-hemolytic.
III. Corynebacterium [S34]: collectively this group of bacteria is referred to as the diphtheroids.
a. They are gram positive, curved peomorphic rods.
i. These are common in clinical laboratories as contaminants because they are very common on the skin.
b. They are aerobic and facultatively anaerobic and grow readily on SBA.
c. A selective media like “cysteine-tellurite” is needed to detect and ID this bacteria when it is thought to be
disease causing.
d. They can appear as Chinese characters in a gram stain.
e. They’re catalase and oxidase positive and typically non-motile.
f. Two main types of corynebacterium are:
i. Corynebacteria jeikeium: causes disease in immune-compromised hosts.
ii. Corynebacteria diptheriae: displays a very classic mechanism of disease.
IV. Diptheria [S35]: an important organism to study because it is spread by respiratory droplets and its mechanism of
disease is via a protein exotoxin. This exotoxin has a direct inhibitory affect on protein synthesis by blocking the
elongation tube necessary for polypeptide chain growth. This shuts down the cellular metabolism of a cell (death).
a. Most affects are seen in the respiratory tract.
b. When it is a respiratory tract cell dying it creates a pseudo-membrane from the bacteria, fibrin, epithelial and
phagocytic cell. This turns into a big mass of necrotic tissue that will cause asphyxiation.
c. The diphtheria toxin can spread to other parts of the body such as the heart, CNS, and adrenal glands.
d. Diptheria has been nearly eradicated in the U.S. because of the vaccine that is given for it along with the
Pertussis and Tetanus vaccine.
i. The “DaPT” vaccine is the vaccine given at an early age that protects against all three:
1. pertussis, tetanus, and diphtheria.
ii. This vaccine has really cut down the number of diphtheria cases we see in the U.S., which is less than five
a year, but it is still prevalent in developing countries.
e. The gene that encodes for the diphtheria exotoxin is contained within a bacteriophage and spread by
transduction.
V. Bacillus [S36]: a common environmental bacteria
a. Is an endospore-forming bacteria along with Clostridium. This makes it a very successful bacteria because
these endospores are very environmentally strong. When environmental conditions are not favorable this
bacteria will generate endospores and wait until the conditions are favorable for growth again.
b. Very resilient bacteria.
c. It is aerobic and facultative anaerobic.
d. It is a gram positive bacilli but can be gram variable.
e. It is often β-hemolytic
f. It is catalase positive and there are several things you have to be concerned with when talking about bacillus.
They are usually only contaminants and do not cause disease unless they are found in sterile body fluids.
i. Bacillus cereus: can cause food poisoning (especially in grains) and ocular infections.
FUN2: 10:00-11:00
Scribe: Brannon Heape
Wednesday, November 5, 2008
Proof: Ryan O’Neill
Dr. Waites
Gram Positive Bacteria/Neisseria & Chlamydia
Page 2 of 3
ii. Anthrax is also in this family. It is Bacillus anthracis.
VI. Bacillus Endospores [S37]: this is just a picture showing an endospore. Nothing else was said.
VII. Bacillus anthracis: Anthrax [S38]: is very rare in the U.S.; it is normally found as skin diseases on people that work
with livestock; many people in the Middle East get the skin disease type from herding animals.
a. So it is transmitted by contact with animal products.
b. The spores can remain infectious for years (why it can be use as a great biological warfare agent).
c. Normally it is received as a cutaneous infection: creates a scar or lesion on the skin that can spread to the
lymphatics and bloodstream.
i. Cutaneous anthrax is not as life threatening because it can be treated & doesn’t spread to the rest of the
body.
1. It typically has a mortality rate of 20% if not treated.
ii. Respiratory Anthrax on the other hand is usually fatal even if it is treated because by the time you become
symptomatic the bacteria has spread too much.
iii. GI tract anthrax is possible as well if you swallow the bacteria.
d. A Bacillus anthracis vaccine is not normally given to the public, but all military people are given the vaccine.
VIII. Anthrax Pathogenesis [S39]: when anthrax enters the cell is produces several toxins:
a. Protective Antigen (PA) binds to host cells and allows the other two toxins, the edema factor and lethal factor, to
enter the host cell.
i. Edema Factor will stimulate adenyl cyclase and cause fluid accumulation.
ii. Lethal Factor will cause the production of cytokines and cause the killing of host cells.
b. Anthrax is special in the fact that it has a protein capsule whereas other bacteria have a carbohydrate capsule.
IX. Anthrax Vaccine [S40]
a. Is made from a virulent, non-encapsulated Bacillus anthracis strain.
b. It requires a series of injections and annual boosters.
c. Again, it is used in the military.
**This is the start of the next lecture slides on Neisseria and Chlamydia.**
X. Objectives [S2]: (read directly off slide)
XI. Neisseria meningitidis [S3]: just a picture
XII. Neisseria meningitidis [S4]:
a. Is an oxidase positive and a gram negative diplococci (kidney bean shaped and facing each other).
b. It is often found in white blood cells and is Capnophilic (like to grow in CO2)
c. It is non-motile
d. It will grow on chocolate and sheep blood agar.
XIII. The Meningococcal Cell Wall [S5]:
a. Because these are gram negative bacteria you can see the outer membrane and inner membrane with the
periplasmic space in between.
b. It has pilli that help mediate attachment.
c. Lipopolysaccharides: the endotoxin part of the bacteria that is responsible for causing “septic shock”.
d. Have a capsule also that can be a virulent factor.
XIV.
Neisseria meningitidis Pathogenesis [S6]:
a. Has a polysaccharide capsule.
b. Lipopolysaccharide (endotoxin) that produces the vascular affects in the host.
c. IgA Protease: cleaves IgA and allows this bacteria to bypass the mucosa.
XV. Diagram [S7]: some people carry Neisseria meningitidis in their respiratory tracts and are not infected. There are
several different serotypes.
a. However, if you do have the bacteria in your nasopharynx and it is a new serotype it can get into your
bloodstream and cross the blood brain barrier entering your cerebral spinal fluid.
b. Typically, this is seen in people in crowded conditions (dorms or military camps).
XVI.
Neisseria meningitidis Serotypes [S8]: there are 13 serotypes based on polysaccharide capsules.
a. A, B, and C serotypes make up more than 90% of the global cases.
b. Type A serotype is what we see in epidemics in developing countries.
c. B, C, and Y are sporadic and outbreaks in developed countries can be seen in crowded places.
XVII. Colony Morphology [S9]: it appears as large gray mucoid colony.
XVIII. Oxidase Positive [S10]: is an important test where you take some bacteria and add the oxidase reagent. If the
cytochrome oxidase enzyme is present in the bacteria you will quickly see a blue color.
XIX.
Neisseria meningitidis Carbohydrate Metabolism [S11]: this bacteria will oxidize glucose and maltose.
a. A way to remember this is: “M” for maltose and “M” for meningitides (Neisseria meningitidis)
FUN2: 10:00-11:00
Scribe: Brannon Heape
Wednesday, November 5, 2008
Proof: Ryan O’Neill
Dr. Waites
Gram Positive Bacteria/Neisseria & Chlamydia
Page 3 of 3
XX.
Neisseria meningitidis Epidemilogy [S12]:
a. In the U.S. this bacteria is the leading cause of bacterial meningitis in older children and young adults.
i. You can have the community- sporadic type or the institutional- outbreak type.
ii. It is spread by respiratory droplets.
iii. About 2800 people in the U.S. will get this disease every year.
iv. It is the type of disease where you can be feeling okay right now but be in the ICU or dead within a couple
of hours.
v. 19% of those that survive this infection will have brain damage and other permanent damage.
b. Worldwide, this is the only form of meningitis that causes epidemics.
XXI.
Graph [S13]: shows that mostly very young children and early adults (high school and college) get the disease.
XXII. Neisseria menigitidis Epidemilogy [S14]:
a. Humans are the only reservoir for this bacterium. It is unique to humans.
b. Spread by respiratory droplets or oral secretions.
c. Normally 10-15% of people will have this bacteria colonized within their nasopharynx and are fine.
XXIII. Neisseria menigitidis Risk Factors [S15]:
a. Household contact of primary case or carrier
b. Crowding (again military, college dorms)
c. Socioeconomic status
d. Exposure to tobacco smoke
e. Recently it has been linked to viral upper respiratory infections. The virus allows bacteria to enter the already
immune-suppressed cells.
f. People without a spleen because as we know it is very important in immune function.
g. People with terminal complement deficiencies will have recurrent infections of this disease.
XXIV. Meningococcal Disease [S16]:
a. Menigitis
b. Bacteremia
c. Meningococcemia (sepsis)
i. Purpura fulminans: caused by endotoxin on the vasculature
ii. Waterhouse – Friderichsen Syndrome: where you have hemorrhaging of the adrenal glands.
XXV. Meningococcal meningitis Clinical Symptoms [S17]:
a. Headache, stiff neck, photophobia (when your eyes hurt from looking at a bright light), altered mental status,
fever, nausea, vomiting, petechial or purpuric rash, and pneumonia.
XXVI. Pictures [S18]
a. Petechia are small hemorrhages in the skin that don’t blanch when you press them. Together they are purpura.
b. We will talk more about these later.
XXVII. Waterhouse – Friderichsen Syndrome [S19]: just a picture showing the hemorrhaging of adrenal glands.
XXVIII. Neisseria meningitidis [S20]: just a picture of a brain from someone who died from N. meningitidis.
a. You can actually die from the increase in intra-cranial pressure.
XXIX. Meningococcal Meningitis Prognosis [S21]
a. Associated with fatal outcome:
i. Shock, purpuric rash, low or normal white blood cell counts, older than 60 years of age, or in a coma.
b. 10% of those who recover:
i. Permanent neurological disability, hearing loss, or limb loss.
XXX. Prevention of Meningococcal Disease [S22]:
a. Chemoprophylaxis after being exposed to it.
b. Vaccination
i. There is a new conjugate vaccine that was licensed in 2005.
XXXI. Meningococcal Vaccine [S23]: recommended for:
a. U.S. Military personnel, Children 11-12 years of age, People at risk during an outbreak, If you are traveling to a
high risk area, College students, Asplenia, Complement deficiencies, Laboratory workers
XXXII. Vaccine Limitations [S24]:
a. There is no protection against the Serotype B yet because the capsule is not immunogenic.
b. It is not useful in children under the age of 2.
c. There are 2 vaccines now available in the U.S.
i. MPSV4- for persons 11-55 years of age
ii. MCV4- persons 2-10 and over 55 years of age.
d. New conjugate vaccine MCV4 may provide longer immunity & reduce people from being carriers of the bacteria.
[End of the 51 minutes]