1.04 - Pathogenesis of Bacterial Infections & Host Resistance to Infections Flashcards
In Acid Fast Stain, what is the color of the stain that Mycobacterium would have?
RED
Its background will be BLUE
It is the the scientific study of the structure, development, function and mode of action of all microorganisms especially with regard to their significance in health and disease.
Microbiology
It is a laboratory equipment that protects you from the organisms and protects the organism from the environment.
Biosafety Cabinet
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➢ Used for identification of microorganisms
➢ Old method, inoculum will be loaded in the tray and after 24h incubation, read/score
basing on chart colors.
BBL Crystal
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➢ Used for bacterial identification (specific) automated identification
➢ Gives a reading depending on the organism that you are looking for
VITEK 2
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➢ A laboratory equipment where blood culture bottles are inserted into specific slots
Blood Culture Machine
**If an organism will grow, the machine will alarm.
(Review the picture)
Used for Mycobacterium tuberculosis culture
BACTEC MGIT 960
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These are the organisms that live on another living organism (human or animal) or inanimate object without causing disease
Normal Microbial Flora
TRUE or FALSE. We become colonised by bacteria from the moment we are born.
True
Why are viruses and parasites not considered member of the microbial flora?
Because they:
➢ Are not commensals
➢ Do not aid the host
Normal microbial flora enters the body through? (2)
Nasal and/or Oral
Normal microbial flora inhabiting the skin?
Gram-positive organisms
staphylococci, micrococci, diptheroids
They inhabit the gingival crevice
Streptococcal anaerobes
The PHARYNX can be a
- point of entry, and
- initial colonization
for which bacteria?
✓ Neisseria
✓ Bordetella
✓ Corynebacterium
✓ Streptococcus spp
What keeps the population of the organisms in the stomach low?
Stomach acidity or acid
It is a potential pathogen that apparently plays a role in the formation of certain ulcer types
Helicobacter pylori
True or False.
▪ Ileum is sparse in normal host.
▪ Duodenal flora contains a moderately mixed flora.
FALSE.
▪ Duodenal flora is sparse in normal host
▪ Ileum contains a moderately mixed flora
Large bowel flora is dense and is composed predominantly of what?
anaerobes
The anaerobes in the large bowel flora participate in which processes?
✓ Bile acid conversion
✓ Vitamin K and ammonia production in the large bowel
The vaginal flora changes with the? (3)
✓ Age of the individual
✓ Vaginal pH
✓ Hormone levels
Give an example of a Transient organism that frequently cause vaginitis
Candida spp
Species of bacteria that exists as normal flora of females
Lactobacillus
Conjunctiva harbors few or no organisms but these two (2) are among the genera most often detected. State them.
Haemophilus and Staphylococcus
It is the capacity to initiate a disease or how a disease occurs
Pathogenesis
State the common bacteria that may be seen in the “skin” of a healthy individual but may cause disease in an immunocompromised host
✓ Staphylococcus aureus
✓ Staphylococcus epidermidis
✓ Propionibacterium acnes
Type of infection that is initiated in the hospital
Nosocomial Infection
It’s the ability of the organism to breach the new host’s defenses
Infectivity
Denotes the capacity of a pathogen to harm the host
Virulence
Transmission occurs when the agent leaves its ___(1)___ or host through a __(2)__, is conveyed by some __(3)__, and enters through an appropriate __(4)__ to infect a __(5)__. This sequence is sometimes called the Chain of Infection.
- reservoir
- portal of exit
- mode of transmission
- portal of entry
- susceptible host
These are pathogens that are capable of establishing infection and causing disease in previously healthy individuals with intact immunological defenses
Primary pathogens
They are pathogens that infect when defenses are impaired/compromised
Opportunistic pathogens
State the two species that part of the normal human flora (skin/mucosal surface) where they cause no harm and may actually have beneficial effects
- Coagulase negative staphylococci
- E. coli
They prevent colonization by other potential pathogens
Factors that can cause the disease. (2)
- Number of the pathogen’s presence
- normal flora depletion –> pathogens adhere to cells - Reduced peristalsis (in the intestine)
- normal flora is not adherent to the mucosal surfaces –> the pathogenic bacteria would adhere to the surfaces
Koch Postulates. Which is wrong?
a. The suspected pathogen must be present in all cases of the disease and in healthy animals.
b. The suspected pathogen must be grown in pure culture.
c. Cells from a pure culture of the suspected pathogen must cause disease in a healthy animal.
d. The suspected pathogen must be re-isolated and shown to be the same as the original.
e. Everything is wrong
f. Everything is correct.
Letter A is wrong.
The suspected pathogen must be present
in all cases of the disease and ABSENT
from healthy animals.
If you got that wrong, read the Koch Postulates again.
Ò.Ó
State the steps involved in the Pathogenesis of bacteria. (TCAIST)
Transmission Colonization Adhesion Invasion Survival in the host Tissue Injury
It is the establishment of a stable population of the bacteria on the host’s skin or mucous membranes.
Colonization
It is where the bacteria REMAINS ADHERENT at the site of colonization in order to proliferate
Adhesion
True or False. Adhesion comes prior to invasion
False.
Adhesion comes prior to colonization
Adhesion involves surface interactions between __(1)__ on the mammalian cell membrane and __(2)__ on the bacterial surface
- Receptors (on the mammalian cell)
2. Ligands (on the bacterial surface)
It is the penetration of the organism to the host cells and tissues
Invasion
Invasion is mediated by a complex array of molecules, described as?
Invasins
Also known as aggressins, and facilitate pathogenesis
Virulence determinants
Physical defense, such as intact skin, is what kind of defense?
First line of defense (Physical Barriers)
This includes:
- Skin
- Mucous membranes
- Chemicals
Neutrophils and lymphocytes are what kind of defense?
2nd line of defense:
Which also includes:
- Phagocytosis
- Complement interferon
- Inflammation
- Fever
Examples of so genetic vehicles from which virulence genes can move from one bacteria to another. (3)
Plasmids
Bacteriophage
Transposons
Antibody and complement alone is considered as what type of pathway?
Classical pathway
Complement alone is what type of pathway?
Alternate pathway
**compared to “Antibody and complement alone” which is the “classical pathway”
It is a secretion of Staphylococcus aureus which prevents phagocytosis
Protein A secretion
Protein M secretion is an anti-phagocytic component of fimbriae of?
Streptococcus pyogenes
A type of immunization where antibodies are directly injected or small dose of antigen is injected into the body in order for us to react and form antibodies
Passive Immunization
A type of immunization where we had the disease and we have memory B cell forming antibodies against it
Acquired Immunization
In acquired immunization, this will be activated and it would be able to recognize that antigen and fight the disease
Memory B cell
They are usually secreted by gram positive bacteria and are sufficiently POTENT that serious effects often result.
Exotoxins
Give examples of exotoxins. (4)
botulism
anthrax
cholera
diphtheria
Are toxic components of
the bacterial cell
envelope
Endotoxins
What is the most potent endotoxic?
Lipopolysaccharide
What happens when endotoxins incite the Kupffer cells?
increase interleukin 1 and Tumor Necrotic Factor –> which cause FEVER
What causes vasodilation of the vessels?
Endotoxins incite the NEUTROPHILS, which increases the production of kinins –> this causes dilatations of the vessels
What is activated if the endotoxins are secreted in small amounts?
Memory B-cells or B lymphocytes
What happens when endotoxins are secreted in large amounts?
bigger increase in interleukin-1 & Tumor Necrosis Factor –> body would go into shock or intravascular coagulation
