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Pathogenic Microbio. Final

Terms in this set (16)

What are the virulence factors of Pseudomonas aeruginosa?
Attachment: Pili and flagella play important role

Invasion: Elastase, phospholipase, and protease enzymes break down tissue and facilitate spread

Evasion: Capsule and LPS provide protection against complement inactivation and phagocytosis

Toxins:
1) Exotoxin A: A-B subunit toxin that inhibits protein synthesis
2) Exoenzymes S and T: cause host cell damage
3) Endotoxin: released from cells as part of LPS
What is the nature of the vaccine used for Haemophilus influenzae?
a conjugated vaccine (combines a weak antigen with a strong antigen as a carrier so that the immune system has a stronger response to the weak antigen) folllowed. This vaccine is T-dependent. It is effective for infants (>2 months). It is the most effective form of control for treatment
Compare Type A and Type C Clostridium perfringens in regard to what disease they cause, due to what toxin, and in what locations it is most common?
- What is Necrotizing Enteritis (Pig-Bel) and what pathogen causes it?
- How diet affects infection by Type C Clostridium perfringens.
Type A:
- disease: soft tissue infections and food poisoning
-toxin: alpha toxin
-location: US and Europe

Type C:
- disease: causes Pig-Bel disease and is associated with necrotizing enteritis
-toxin: beta toxin
-location: Papau New Guinea

Necrotizing enteritis is a necrotizing infection of the small intestine. 50% of those infected are at risk of mortality.

Infection by Type C Clostridium perfringens is associated with meat consumption. The bacteria's spores can survive cooking, germinate, and grow
Name the Clostridium species that causes Flaccid Paralysis and what virulence factor it uses to cause such a symptom?
- What is the common risk factor for infant botulism?
1. Clostridium botulinum causes Flaccid Paralysis.
Virulence Factor used: toxins that affect neurotransmitters.

2. common risk factor for infant botulism is certain foods, particularly honey
Name the Clostridium species that causes Tetanus and what virulence factor it uses to cause such a disease and what is the nature of its vaccine?
- What is cephalic tetanus?
Clostridium tetani is responsible for tetanus. Virulence factors used:
1) disease occurs when host is inocculated with spores.
2) tetanospasmin toxin affects neurotransmitters in nerve cells leading to spastic paralysis. Toxin binding is irreversible

Vaccine has a tetanus toxoid

Cephalic tetanus is a form of localized tetanus that affects the head and usually follows a head wound. It often has a poor prognosis
What disease caused by Bordetella, its symptoms, and what is the nature of its vaccine?
Pertussis (whooping cough) is caused by Bordetella.

Symptoms: 3 stages
1) catarrhal: Rhinorrhea, malaise, fever, anorexia
2) paroxysmal: repetitive cough with whoops, vomiting, leukocytosis
3) convalescent: diminished paroxysmal cough, development of secondary conditions (pneumonia, seizures, encephalopathy)

Vaccine: Subunit vaccine made from purified toxin and antigens. It is known as the acellular pertussis vaccine. it is administered with Diphtheria and Tetanus vaccines (DTaP)
What are the symptoms of Tularemia, what microbe causes it, and which virulence mechanism is a distinguishing characteristic of this infecting microbe?
- What reasons Francisella is considered a perfect bio-warfare agent?
- what risk factors to get Tularemia?
Symptoms: ulcer at the site of infection, pneumonia

Microbe: Francisella tularensis

Distinguished virulence mechanism: It requires a low infectious dose (low as 10 cells). Facultative intracellular pathogen that infects macrophages.

Perfect bio-warfare agent because: highly infectious, high morbidity and mortality, large quantities are easily assembled, stability in the environment, difficult to diagnose

Risk factors: hunting, landscaping, working in a lab with the pathogen
What is Weil's disease and what spirochete is causing it?
It is a disease that includes renal failure, liver failure, vascular collapse. Mortality rate is 10-15%.

It is caused by Leptospira.
What is Brucellosis and what microbe causes it?
It is a disease in animals normally affects the reproductive organs and causes abortions. This disease is variable in humans. It is caused by Brucella species. Those with the most clinical importance: B. melitensis, B. suis, B abortus
What is the most common (leading) vector-borne disease in the US transmitted by the bite of deer ticks, what are the symptoms and how to protect against it?
Lyme disease.

Symptoms: erythema migrans develops at inocculation site, fever and muscle pain ensue

treatment: Penicillin or tetracycline
What are the symptoms of Legionella infection, what source of infection is likely, and what antibiotics needed for its treatment?
Symptoms:
In pontiac fever, pneumonia does not occur and symptoms are nonspecific
In legionnaires' disease, multiple diseases involving pneumonia occur.

likely source of infection: cooling towers, water misters, water fountains

antibiotics needed: macrolides and fluoroquinolones
Describe in details all Syphilis stages with their symptoms, what diagnostic tool is best to detect each stage, what antibiotics used to treat this disease?
Stages:
1) incubation

2) primary-
symptoms: chancre, lymphadenopathy
diagnostic tool: serology, microscopy

3) secondary
symptoms: rash, generalized lymphadenopathy
diagnostic tool: serology, microscopy

4) latent
diagnostic tool: serology

5) late or tertiary
symptoms: gummas- granulamatous lesions that are found in skin, bone, and other tissues
diagnostic tool: serology

Antibiotics: penicillin, tetracycline can be used for penicillin sensitive patients
What is the unique developmental life cycle of Chlamydia and what diseases it cause?
Life cycle:(8steps)
A. elementary body (EB) attaches to surface of cell
B. endocytosis of EB occurs
C. EB is in endosome which does NOT fuse with lysosome
D. EB recognizes reticulate body (RB) in endosome
E. RB replicates via binary fission
F. RBs are reorganized to EBs
G. Inclusion granule has both RBs and EBs
H. C. trachomatis: reverse endocytosis

Disease: trachoma
What are the symptoms of malaria, where it is common, what vector is transmitting it and what is its life cycle?
1) Paroxysm involving 3 stages: cold stage (shivering), hot stage (high fever), sweating stage (fever drops)

2) location: central africa, south america, south asia

3) vector: mosquito

4) life cycle:(9steps)
- mosquito injects sporozoites into humans during blood meal
- sporozoites travel to the liver, and invade and replicate in hepatocytes
- 1000s of merozoites are released into the blood stream where they invade erythrocytes
- every 48-72 hrs, erythrocytes rupture, releasing more merozoites
- gametes develop
-Gametes are taken up by a mosquito in a blood meal
- fertilization in the mosquito gut resulting in the formation of an ookinete
- ookinete invades the mosquito gut lining and develops in an oocyst
-oocysts rupture, releasing 1000s of sporozoites, which travels to the salivary glands to complete to complete the life cycle
Explain why protease inhibitors can be used as anti HIV drugs?
- What are CCR5 and CXCR4 and which cells are they found on?
- What genes are important in the pathogenicity and the life cycle of HIV?
- How inhibiting their products are considered treatment drug targets?*
- protease inhibitors inhibit the protease that is necessary to cut the polypeptide
- HIV requires a second host cell receptor in addition to CD4. CCR5 is found on macrophage cells and memory T cells, CXCR4 is found on unactivated (naïve) T cells

1. gag encodes capsid proteins
2. pol encodes the DNA polymerase (reverse transcriptase) and integrase
3. env encode envelop glycoprotein

treatment:
1) reverse transcriptase inhibitors- two types: nucleoside analogue inhibitors are defective nucleic acids that stop transcription. Non-nucleoside analogue inhibitors directly inhibit reverse transcriptase activity
2) Protease inhibitors- inhibit the protease that is necessary to cut the polypeptide
16. Importance and danger of Candida albicans as an opportunistic pathogen in hospitalized patients?

What is fungal dimorphism?

How to differentiate between the saprobic phase and the parasitic phase?

Why do you think thermal dimorphism is necessary for Blastomyces dermatitidis pathogenicity discussing why shedding the glycoprotein (WI1) by virulent strains is also needed for pathogenicity?
1) Candida spp. are the most common of the opportunistic fungal pathogens. Opportunistic pathogens have a commensal relationship with the host, but can cause disease if the hosts resistance is altered. C. albicans is the most prevalent of the Candida species. It's highest rates can be seen in individuals aged 1-18.

2) Fungal Dimorphism is the ability to exist in alternate morphogenic forms and is one of several virulence factors that allows these fungi to cope with the environmental conditions of the host.

3) The saprobic phase is characterized by filamentous septated hyphae and can be found in soil or decaying vegetation. Parasitic phase is adapted to grow at 37 C and is adapted to reproduce asexually in the host respiratory system.

4) Blastomyces dermatitidis transforms into the parasitic yeast phase during thermal dimorphism. This causes the cell to transform to a larger yeast cell that resists phagocytic attack during pathogenesis. One way that these yeast cells do this is through shedding their cell wall glycoprotein. Virulents strains shed the glycoprotein (WI-1) during growth to avoid recognition by the hosts macrophages.
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