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Microbial ecology & transmission (1) Flashcards

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Biology 101 flashcards
1
Q

Microbes are ubiquitous in nature. (Explain)

A
  1. occupy different niches
  2. tolerate different temperatures
  3. utilize different nutrients
  4. produce different metabolites
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2
Q

What is Microbial Ecology?

A

It is the study of interactions between microbes & their environment.

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3
Q

The interaction between host & organism is referred to as

……………….

A

symbiosis

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4
Q

What are the 3 forms of symbiotic relationships?

A
  1. Mutualism
  2. Commensalism
  3. Parasitism
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5
Q

What is Mutualism & give me an example?

A
  • Both the microorganism & the body work together.
  • An example of this relationship would the presence E.coli in the human intestine.
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6
Q

What is Commensalism & give me an example?

A
  • Either the body or the microorganism benefits, while the other is not affected.
  • Example: normal flora that inhabit the eyes
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7
Q

What is Parasitism & give me an example?

A
  • One organism benefits at the expense of the other.
  • Example: parasites use the gastrointestinal tract of a human
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8
Q

Microorganisms can be?

A
  1. Parasitic = Pathogens (Microbes that cause disease)
  2. Non parasitic = non pathogens (Microbes that do not cause disease)
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9
Q

Define Biofilm & explain its function?

A
  1. A community of microbial cells attached irreversibly to the substrate at the interface or to each other, embedded in an exopolysaccharidic matrix.
  2. Biofilm bacteria release antigens & stimulate the production of antibodies, yet bacteria residing in biofilms are resistant to these defense mechanisms.
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10
Q

List the steps in the formation of biofilms.

A
  1. Individual cells populate the surface (initial attachment)
  2. Extra polymeric substances (EPS) are produced & attachment is irreversible
  3. Saturation
  4. Biofilm architecture develops and matures. Communicate via quorum sensing
  5. Single cells are released from the biofilm
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11
Q

What are the stages that comprise Biofim Formation?

A
  1. reversible attachment
  2. irreversible attachment
  3. colonization
  4. maturation
  5. dispersion
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12
Q

List the names of the

Bacteria associated with biofilms

A
  • Gram-Positive bacteria
  1. Enterococcus faecalis
  2. Staphylococcus aureus
  3. Staphylococcus epidermidis
  4. Streptococcus viridans
  5. Bacillus cereus - Candida albicans
  • Gram- negative bacteria
  1. Escherichia coli
  2. Klebsiella pneumoniae
  3. Proteus mirabillis
  4. Pseudomonas aeruginosa
  5. Salmonella enterica
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13
Q

What are the Associated diseases or consequences of

Prosthetic valve?

A

Prosthetic valve endocarditis

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14
Q

What are the associated diseases or consequences of

Contact lenses?

A

Keratitis

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15
Q

What are the associated diseases or consequences of

Intravascular catheters?

A

Septicemia + Endocarditis

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16
Q

What are the associated diseases or consequences of

Total Artificial Heart?

A

Septicemia + Device Failure

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17
Q

What are the associated diseases or consequences of

Urinary Catheters?

A

Bacteriuria

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18
Q

What are the associated diseases or consequences of

Joint Replacement?

A

Septicemia + device failure

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19
Q

What are the associated diseases or consequences of

Endotracheal Tube?

A

Pneumonia

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20
Q

What are the associated diseases or consequences of

Voice Prostheses?

A

Prosthesis failure

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21
Q

S. epidermidis

A
  1. Prosthetic valve
  2. Contact lenses
  3. Intravascular catheters
  4. Total artificial heart
  5. Joint replacement
  6. Endotracheal tube
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22
Q

S. aureus

A
  1. Intravascular Catheters
  2. Total Artificial Heart
  3. Joint Replacement
  4. Endotracheal tube
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23
Q

P. aeruginosa

A
  1. Contact Lenses
  2. Total Artificial Heart
  3. Urinary Catheters
  4. Endotracheal tube
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24
Q

E. Coli

A
  1. Urinary Catheters
  2. Endotracheal Tube
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25
Q

E. faecalis

A

Urinary Catheters

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26
Q

Proteus mirabilis

A

Urinary Catheters

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27
Q

What are the organisms found in

Urinary Catheters?

A
  1. E. coli
  2. E. faecalis
  3. Proteus mirabilis
  4. P.aeruginosa
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28
Q

S. sanguis

A

Prosthetic Valve

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29
Q

What organism is found in

Voice Prostheses?

A

streptococci staphylococci

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30
Q

What are the elements that cause any disease or infection?

A
  1. Pathogen
  2. Host
  3. Entry
  4. Transmission
  5. Environment
  6. Exit
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31
Q

List the elements that cause any disease or infection.

A
  1. The pathogen: the organism causing the infection
  2. The host: the infected person or animal
  3. The entry: the method the pathogen uses to enter the body of the susceptible host
  4. Transmission: how the pathogen is transferred from host to susceptible host
  5. The environment: the environment in which transmission of the pathogen takes place.
  6. The exit: the method the pathogen uses to leave the body of the host
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32
Q

What is the the first link in the infectious disease cycle?

A

Pathogen

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33
Q

What are Pathogens?

A

are organisms that have the potential to
produce a disease (pathogenicity)

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34
Q

Pathogens are divided into 2 types.
What are they?

A
  1. Primary Pathogens
  2. Opportunistic Pathogens
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35
Q

What are primary pathogens & list some examples?

A
  • Always cause disease.
  • ​E.g.,
    • Vibrio cholerae
    • M. tuberculosis
    • Treponema pallidum
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36
Q

List examples of primary pathogens.

A
  1. Vibrio cholerae
  2. M. tuberculosis
  3. Treponema pallidum
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37
Q

What are opportunistic pathogens & list some examples?

A
  • Resident or transient flora that can cause disease under certain conditions.
  • E.g.,
    • Staphylococcus aureus
    • Escherichia coli
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38
Q

List examples of opportunistic pathogens.

A
  1. Staphylococcus aureus
  2. Escherichia coli
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39
Q

What is potential pathogenicity?

A

It is the ability to cause a disease.

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40
Q

What are the factors that determine potential pathogenicity?

A
  1. number of pathogens
  2. pathogens virulence
  3. nature & magnitude of host defenses
41
Q

Steps in the infection process

A
  1. Portals of entry
  2. Number of invading microbes
  3. Adherence
  4. Penetration/evasion of host defenses
  5. Damage to host cells/cytopathic effects
42
Q

Penetration/evasion of host defenses

A
  • Capsules
  • Cell wall components
  • Enzymes
  • Cytoskeleton
43
Q

What may specific host defenses include?

A
  1. Skin & mucosal secretions
  2. Non-specific local responses (pH)
  3. Non-specific inflammatory responses
  4. Specific immune responses (lymphocytes)
44
Q

What is a reservoir?

A

A continuous source of infection (habitat).

Reservoirs can be human, animals or non-living things.

45
Q

What can reservoirs be?

A

Reservoirs can be

  1. human
  2. animals
  3. non-living things
46
Q

Human reservoirs

What is the principal living reservoir of human disease?

A

the human body itself

47
Q

Are human reservoirs carriers?

A

Yes.

Human reservoirs are also carriers.

48
Q

What is the definition of carrier?

A
  • A person or animal that harbors an infectious agent without discernible clinical disease & serves as ampotential source of infection.
  • i.e can transmit the agent to another susceptible person or animal.
49
Q

Spread of infection

What are the types of carriers?

A
  1. Asymptomatic carriers
  2. Incubation carriers
  3. Convalescent carrier
  4. Chronic carrier
50
Q

Define asymptomatic carriers?

A

A person who is infected but without symptoms.
E.g., healthcare workers

51
Q

Define incubation carriers?

A

Are in the early stages of infection

E.g., sexually transmitted diseases = AIDS

52
Q

Define convalescent carriers?

A

in the late stages of recovery
E.g., typhoid. (typhoid Mary)

53
Q

Define chronic carriers?

A

carries infection for long periods after recovery

54
Q

What are the sources and reservoirs of infection?

A
  1. Human reservoir
  2. Animal reservoir
  3. Mechanical vector/Non-living - Soil & Water
  4. Plants (Phytosis)
55
Q

Define zoonoses?

A
  • Are diseases that occur primarily in animals & can be transmitted to humans.
  • E.g.,
    • some types of influenza
    • Avian flu - انفلونزا الطيور
    • SARS virus anthrax - فيروس الجمرة الخبيثة
    • Rabies - داء الكلب
    • Brucellosis
    • Salmonellosis
    • Lyme disease
    • Pneumonic plague - طاعون رئوي
56
Q

What is a vector & list some examples?

A
  • Is a live animal that transmits an infectious agent from one host to another.
  • Examples:
    • Arthropods = fleas, mosquitoes, flies, ticks, & cockroaches
    • Larger animals = birds & bats
57
Q

Plants (Phytosis)

Spread of infection is caused by what?

A
  • parasitic plant
  • e.g., fungus (dermatomycoses), which is a fungal infection of the skin, especially by a dermatophyte.
58
Q

What are the two types of vectors?

A
  • Biological vector – participates in the pathogen’s life cycle
  • Mechanical vector – not necessary participate in the pathogen’s life cycle
59
Q

Mechanical Vectors

A
  • Soil:
    • Clostridium botulinum
    • Cl. Tetani
    • Fungi
  • Water:
    • may be contaminated with human & animal faeces
    • act as reservoir for several pathogens
60
Q

What are the 2 classifications of diseases?

A
  • Communicable diseases: occur when a pathogen is transmitted from host to host directly or indirectly.
  • Non communicable diseases: are not spread from host to host.
61
Q

Summery of modes of acquiring infection

A

The doctor said pay attention to this table

62
Q

List examples of disease spread by direct contact?

A
  1. cutaneous anthrax
  2. genital warts
  3. gonorrhea
  4. syphilis
  5. rabies
63
Q

List examples of disease spread by indirect contact?

A
  1. Common cold
  2. Enterovirus infections
  3. Influenza
64
Q

Examples of droplet transmission- sneezing?

A
  1. Whooping cough
  2. Tb
  3. Strep throat
65
Q

Examples of vehicle transmission - Airborne

A
  1. chicken pox
  2. influenza
  3. Tb
  4. pulmonary anthrax
  5. histoplasmosis
66
Q

Examples of vehicle transmission - Waterborne

A
  1. Cholera
  2. Giardia diarrhea
67
Q

Examples of vector transmission - Mechanical

A
  1. E. coli
  2. Diarrhea
  3. Salmonellosis
68
Q

Examples of vector transmission - Biological

A
  1. malaria
  2. denque fever
  3. lyme disease
69
Q

Prevention & control of Diseases

What are the 3 kinds of control measures?

A
  1. Those directed towards reducing/eliminating the source/reservoir of infection.
  2. Those designed to break the connection between the source of infection & susceptible individuals.
  3. Control measures to reduce the number of susceptible individuals & raise the general level of herd immunity.
70
Q

List the control measures directed towards reducing or eliminating the
source or reservoir of infection. (1st CM)

A
  1. quarantine & isolation of cases & carriers
  2. destruction of animal reservoirs of infection
  3. treatment of sewage to reduce water contamination
  4. therapy that reduces/eliminates infectivity of the individual
71
Q

List the control measures designed to break the connection between the
source of infection and susceptible individuals. (2nd CM)

A
  1. chlorination of water supplies
  2. pasteurization of milk
  3. supervision & inspection of food & people who handle food
  4. destruction of vectors by spraying with insecticides
72
Q

List the control measures used to to reduce the number of susceptible individuals & raise the general level of herd immunity. (3rd CM)

A
  1. Passive immunization to give a temporary immunity following exposure to a pathogen or when a disease threatens to take an epidemic form.
  2. Active immunization to protect the individual from the pathogen and the host population from the epidemic.
73
Q

What are the benefits of nonpathogenic microorganisms?

A
  1. Contribution to health - normal flora
  2. Food production - yogurt, bread, spreads=vegemite
  3. Chemical production -
    • enzymes
    • antibiotics
    • vitamins
  4. Genetic engineering - production of hormones & insulin
  5. Elimination of pollution -
    • bioremediation
    • degradation of toxic compounds
    1. cleaning up of oil spills
    2. polychlorinated biophenyls (PCB)
74
Q

What do you know about

normal bacterial flora?

A
  • The normal flora or microbiota of humans includes bacteria, fungi, and protozoans that resides permanently on the body without causing disease.
  • Normal flora can be found in:
    • gastrointestinal (GI) tract
    • respiratory tract
    • genitourinary tract
    • skin.
  • Normal flora protect us from invasion & proliferation of pathogenic (disease-causing) microbes by competing for space & nutrients.
75
Q

What are the benefits of

normal bacterial flora?

A
  1. Aid in the digestion of food
  2. Compete with pathogens for nutrients & adhesion sites
  3. Inactivate pathogenic bacterial toxins or metabolites
  4. Produce substances that inhibit pathogens’ growth
  5. Stimulate nonspecific immunity
76
Q

Why study microbial normal flora?

A
  • Understanding the different microorganisms at specific locations provides insight into possible infections that might result from injury to these body sites.
  • A knowledge of the normal flora in the infected part of the body gives the physician perspective on the possible source & significance of microorganisms isolated from the infected site.
  • Provides understanding of the causes & consequences of overgrowth by microorganisms normally absent at a specific body site.
77
Q

Distribution of normal flora in different body sites

(1)

A
78
Q

Distribution of normal flora in different body sites

(2)

A
79
Q

Distribution of normal flora in different body sites

(3)

A
  • Small Intestine
    1. ​​​​​Enterococcus faecalis
    2. Lactobacilli
    3. Diphtheroids
    4. Candida
      • are occasionally present in the jejunum
  • Large intestine (Colon)​
    1. ​Over 300 different bacterial species have been isolated from human faeces & they consists primarily of:
      • anaerobic
      • gram-negative non sporing bacteria
      • gram-positive spore forming
      • non sporing rods.
    2. Yeast (Candida albican) & protozoa may occur as harmless commensal, e.g.,
      • T. hominis
      • Entamoeba hartmani
      • Endolimax nana
      • Iodema butschlii
80
Q

What are the functions of gut microbiota?

A
  1. Strengthen intestinal epithelium
  2. Immunostimulatory effect
  3. Induction of regulatory T Cells (Tregs)
  4. Stimulate angiogenesis
  5. Antiinflamatory
  6. Antimicrobial effect
81
Q

What are the functions of gut microbiota?

A
  1. Strengthen intestinal epithelium
    • Help maintain the integrity of the mucosal barrier, provide nutrients, such as vitamins, and to protect against pathogens
  2. Immunostimulatory effect
    • ​The interaction between commensal microbiota & the mucosal immune system is crucial for proper immune function.
  3. Induction of regulatory T Cells (Tregs)
    • Subpopulation of T-cells that modulate the immune system, maintain tolerance to self antigen, & prevent autoimmune diseases​.
  4. Stimulate angiogenesis
    • ​(development of new blood vessels from preexisting blood vessels)
  5. Anti-inflammatory
  6. Antimicrobial effect
    • ​​colonization by competing for attachment sites & nutrient sources & by producing antimicrobial substances.
82
Q

Distribution of normal flora in different body sites

(4)

A

Genitourinary Tract:

  1. The upper genitourinary tract: kidneys, ureters & urinary bladder, are usually free of microorganisms.
  2. In both males & females,
    • S. epidermidis
    • E. faecalis
    • Corynebacterium spp.
      • are usually present in the distal portion of the urethra.
    • Neisseria & Enterobacteriacae are found occasionally.
  3. In the adult female genital tract,
    • Acid-tolerant lactobacilli
    • Lactobacillus acidophilus
      • are dominant & maintain the pH of the vagina at between 4.4 & 4.6.
  4. Others are Candida albicans & Gardnerella vaginalis
83
Q
  • We can carry many bacteria in our bodies without showing any sign of disease, but that doesn’t make us carriers.
  • For a person to be considered a carrier he should be able to ……………………………
A

transmit this bacteria to another person

84
Q

What does asymptomatic carriers include?

A
  • incubation carriers
  • convalescent carrier
85
Q

What do you know about a convalescent carrier & give me an example?

A
  • A convalescent carrier is someone who was sick then he recovered, but the microorganisms are not totally eliminated from his system, so this person can continue to transmit the microbes to other people and make them sick even if he himself shows no signs of sickness.
  • An example of this is Typhoid Mary, she was a housekeeper in NY city in the old ages when knowledge & awareness about transmission of disease was not good, she was a cook & she worked for a lot of people & every person she worked with or served died. So when people realized she was the common factor in this cycle of death they said she was a witch, but one person suggested to investigate her to check if there is another cause for these deaths. They took a stool sample from her & discovered that she was carrying salmonella typhoid but was immune herself & because of poor hygiene she excrete the salmonella in her system into the food, contaminating it. The people she served had no immunity to it, so they died.
86
Q

Give me an example of passive carriers.

A

health care workers

87
Q

Human carriers can be?

A
  1. Chronic carriers:
    • in this case no mater what we do the patient still has the infection
      * *Example**, a patient carrying the same strand of bacteria in there nose for a really long time, and this can be caused by a lot of factors like: a poor immune system that can’t get rid of the infection or recolonization, which occurs when the environment is contaminated.
  2. Transitional carriers: present in the body for a short time
  3. Intermediate carriers : people are treated but it comes back
88
Q

What do you know about biological vectors & give me an example?

A
  1. Biological vector – participates in the pathogen’s life cycle
  2. Example of biological vector is Malaria.
    • They have a life cycle in mosquitos, so if we eliminate mosquitos we eliminate malaria. We have another disease known as Belharzia (schistosomiasis), which is found in snails or dirty water, & it is involved in the life cycle of its vector.
  • Malaria ➡️ Mosquitos
  • Belharzia (schistosomiasis) ➡️ Snails or dirty water
89
Q

So many farmers get infected with what?

A

Clostridium tetani spores found in the soil

90
Q

Name 2 water borne diseases

A
  1. Cholera
  2. Diarrhea
91
Q

Air travel can lead to the transmission of ……………..

A

Tuberculosis

92
Q

Name 2 diseases that had animal reservoirs & resulted in the death of many animals as a control measure?

A
  1. Foot & mouth disease
  2. Swine flu disease - انفلونزا الخنازين
93
Q

What do you know about primary pathogens?

A
  • Primary pathogen: a pathogen that always causes a disease.
  • They are never friendly, e.g.,
    1. mycobacterium tuberculosis
    2. cholera
94
Q

What do you know about opportunistic pathogens?

A
  • Opportunistic pathogens: a pathogen that sometimes causes a disease.
  • Examples:
    1. Staphylococcus aureus
    2. E. Coli
95
Q

Where can you find the normal flora/microbiota?

A

Everywhere except the brain & cerebrospinal fluid

96
Q

What is the most common specimen to investigate in the lab?

A

Urine

97
Q

Does pathogenic organisms have capsules?

A

Pathogenic organisms have capsules,
while nonpathogenic don’t.

98
Q

What do you know about microorganisms in the stomach & large intestine?

A
  1. Stomach:
    • Most microorganisms will not survive in the acidic pH, so we have only transient flora in the stomach.
    • Microorganisms that cause gastritis like helicobacter bacteria can be found there bcz it produces enzyme urease that makes it alkaline.
  2. Large intestine:
    • is where u have the largest number of microorganisms.

Microbiology (1 decks)

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