Microbial ecology & transmission (1) Flashcards
1
Q
Microbes are ubiquitous in nature. (Explain)
A
- occupy different niches
- tolerate different temperatures
- utilize different nutrients
- produce different metabolites
2
Q
What is Microbial Ecology?
A
It is the study of interactions between microbes & their environment.
3
Q
The interaction between host & organism is referred to as
……………….
A
symbiosis
4
Q
What are the 3 forms of symbiotic relationships?
A
- Mutualism
- Commensalism
- Parasitism
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.
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
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
8
Q
Microorganisms can be?
A
- Parasitic = Pathogens (Microbes that cause disease)
- Non parasitic = non pathogens (Microbes that do not cause disease)
9
Q
Define Biofilm & explain its function?
A
- A community of microbial cells attached irreversibly to the substrate at the interface or to each other, embedded in an exopolysaccharidic matrix.
- Biofilm bacteria release antigens & stimulate the production of antibodies, yet bacteria residing in biofilms are resistant to these defense mechanisms.
10
Q
List the steps in the formation of biofilms.
A
- Individual cells populate the surface (initial attachment)
- Extra polymeric substances (EPS) are produced & attachment is irreversible
- Saturation
- Biofilm architecture develops and matures. Communicate via quorum sensing
- Single cells are released from the biofilm
11
Q
What are the stages that comprise Biofim Formation?
A
- reversible attachment
- irreversible attachment
- colonization
- maturation
- dispersion
12
Q
List the names of the
Bacteria associated with biofilms
A
- Gram-Positive bacteria
- Enterococcus faecalis
- Staphylococcus aureus
- Staphylococcus epidermidis
- Streptococcus viridans
- Bacillus cereus - Candida albicans
- Gram- negative bacteria
- Escherichia coli
- Klebsiella pneumoniae
- Proteus mirabillis
- Pseudomonas aeruginosa
- Salmonella enterica
13
Q
What are the Associated diseases or consequences of
Prosthetic valve?
A
Prosthetic valve endocarditis
14
Q
What are the associated diseases or consequences of
Contact lenses?
A
Keratitis
15
Q
What are the associated diseases or consequences of
Intravascular catheters?
A
Septicemia + Endocarditis
16
Q
What are the associated diseases or consequences of
Total Artificial Heart?
A
Septicemia + Device Failure
17
Q
What are the associated diseases or consequences of
Urinary Catheters?
A
Bacteriuria
18
Q
What are the associated diseases or consequences of
Joint Replacement?
A
Septicemia + device failure
19
Q
What are the associated diseases or consequences of
Endotracheal Tube?
A
Pneumonia
20
Q
What are the associated diseases or consequences of
Voice Prostheses?
A
Prosthesis failure
21
Q
S. epidermidis
A
- Prosthetic valve
- Contact lenses
- Intravascular catheters
- Total artificial heart
- Joint replacement
- Endotracheal tube
22
Q
S. aureus
A
- Intravascular Catheters
- Total Artificial Heart
- Joint Replacement
- Endotracheal tube
23
Q
P. aeruginosa
A
- Contact Lenses
- Total Artificial Heart
- Urinary Catheters
- Endotracheal tube
24
Q
E. Coli
A
- Urinary Catheters
- Endotracheal Tube
25
E. faecalis
Urinary Catheters
26
Proteus mirabilis
Urinary Catheters
27
What are the organisms found in
**Urinary Catheters**?
1. E. coli
2. **E. faecalis**
3. **Proteus mirabilis**
4. P.aeruginosa
28
S. sanguis
Prosthetic Valve
29
What organism is found in
**Voice Prostheses**?
streptococci staphylococci
30
What are the **elements** that cause any disease or infection?
1. Pathogen
2. Host
3. Entry
4. Transmission
5. Environment
6. Exit
31
List the **elements** that cause any disease or infection.
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
32
What is the the **first link in the infectious disease cycle**?
Pathogen
33
What are **Pathogens**?
are organisms that have the potential to
produce a disease (pathogenicity)
34
Pathogens are divided into 2 types.
What are they?
1. Primary Pathogens
2. Opportunistic Pathogens
35
What are **primary pathogens** & list some **examples**?
* Always cause disease.
* E.g.,
* Vibrio cholerae
* M. tuberculosis
* Treponema pallidum
36
List examples of **primary pathogens**.
1. **Vibrio cholerae**
2. **M. tuberculosis**
3. **Treponema pallidum**
37
What are **opportunistic pathogens** & list some **examples**?
* **_Resident or transient flora_** that can cause disease under certain conditions.
* E.g.,
* **Staphylococcus aureus**
* **Escherichia coli**
38
List examples of opportunistic pathogens.
1. **Staphylococcus aureus**
2. **Escherichia coli**
39
What is **potential pathogenicity**?
It is the **ability to cause a disease**.
40
What are the *factors* that determine **potential pathogenicity**?
1. **number** of pathogens
2. pathogens **virulence**
3. **nature & magnitude** of _host defenses_
41
Steps in the infection process
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
Penetration/evasion of host defenses
* Capsules
* Cell wall components
* Enzymes
* Cytoskeleton
43
What may **specific host _defenses_** include?
1. Skin & mucosal secretions
2. Non-specific _local_ responses (**pH**)
3. Non-specific _inflammatory_ responses
4. Specific immune responses (**lymphocytes**)
44
What is a **reservoir**?
A continuous source of infection (habitat).
Reservoirs can be **human**, **animals** or **non-living things**.
45
What can **reservoirs** be?
_Reservoirs can be_
1. **human**
2. **animals**
3. **non-living things**
46
_Human reservoirs_
What is the **principal living reservoir of human disease**?
the human body itself
47
Are **human reservoirs** carriers?
**Yes**.
**Human reservoirs** are also **carriers**.
48
What is the definition of **carrier**?
* 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
_Spread of infection_
What are the **types of carriers**?
1. **Asymptomatic** carriers
2. **Incubation** carriers
3. **Convalescent** carrier
4. **Chronic** carrier
50
Define **asymptomatic** carriers?
A person who is infected **but** without symptoms.
E.g., **healthcare workers**
51
Define **incubation** carriers?
Are in the early stages of infection
E.g., **sexually transmitted diseases = AIDS**
52
Define **convalescent** carriers?
in the late stages of recovery
E.g., **typhoid. (typhoid Mary)**
53
Define **chronic** carriers?
carries infection for long periods after recovery
54
What are the sources and reservoirs of infection?
1. Human reservoir
2. Animal reservoir
3. Mechanical vector/Non-living - **Soil & Water**
4. Plants (**Phytosis**)
55
Define **zoonoses**?
* **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
What is a **vector** & list some **examples**?
* **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
**_Plants (Phytosis)_**
Spread of infection is caused by what?
* parasitic plant
* e.g., fungus (**dermatomycoses**), which is a fungal infection of the skin, especially by a **dermatophyte**.
58
What are the two types of vectors?
* **Biological** vector – **participates** in the pathogen’s life cycle
* **Mechanical** vector – **not necessary participate** in the pathogen’s life cycle
59
Mechanical Vectors
* _Soil_:
* **Clostridium botulinum**
* **Cl. Tetani**
* **Fungi**
* _Water_:
* may be *contaminated* with human & animal faeces
* act as *reservoir* for several pathogens
60
What are the 2 classifications of diseases?
* **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
Summery of modes of acquiring infection
The doctor said pay attention to this table
62
List examples of disease spread by **direct contact**?
1. cutaneous anthrax
2. genital warts
3. gonorrhea
4. syphilis
5. rabies
63
List examples of disease spread by **indirect contact**?
1. Common cold
2. Enterovirus infections
3. Influenza
64
Examples of **droplet transmission**- sneezing?
1. Whooping cough
2. Tb
3. Strep throat
65
Examples of vehicle transmission - **Airborne**
1. chicken pox
2. influenza
3. Tb
4. pulmonary anthrax
5. histoplasmosis
66
Examples of vehicle transmission - **Waterborne**
1. Cholera
2. Giardia diarrhea
67
Examples of vector transmission - **Mechanical**
1. E. coli
2. Diarrhea
3. Salmonellosis
68
Examples of vector transmission - **Biological**
1. malaria
2. denque fever
3. lyme disease
69
_Prevention & control of Diseases_
What are the **3** kinds of **control measures**?
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
List the control measures directed towards reducing or eliminating the
source or reservoir of infection. (1st CM)
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
List the control measures designed to break the connection between the
source of infection and susceptible individuals. (2nd CM)
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
List the control measures used to to reduce the number of susceptible individuals & raise the general level of herd immunity. (3rd CM)
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
What are the **benefits of nonpathogenic microorganisms**?
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
What do you know about
**normal bacterial flora**?
* 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
What are the **benefits** of
**normal bacterial flora**?
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
**Why** study microbial **normal flora**?
* 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
Distribution of normal flora in different body sites
(1)
78
Distribution of normal flora in different body sites
(2)
79
Distribution of normal flora in different body sites
(3)
* **_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
What are the **functions of gut microbiota**?
1. **Strengthen intestinal epithelium**
2. **Immunostimulatory effect**
3. **Induction of regulatory T Cells (Tregs)**
4. **Stimulate angiogenesis**
5. **Antiinflamatory**
6. **Antimicrobial effect**
81
What are the **functions of gut microbiota**?
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
Distribution of normal flora in different body sites
(4)
**_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
* 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 .................................
**transmit** this bacteria to another person
84
What does **asymptomatic carriers** include?
* **incubation** carriers
* **convalescent** carrier
85
What do you know about a **convalescent** carrier & give me an **example**?
* 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
Give me an example of **passive** carriers.
health care workers
87
Human carriers can be?
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
What do you know about **biological vectors** & give me an **example**?
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
So many **farmers** get infected with what?
**Clostridium tetani** spores found in the **soil**
90
Name 2 **water borne** diseases
1. Cholera
2. Diarrhea
91
**Air travel** can lead to the transmission of .................
Tuberculosis
92
Name 2 diseases that had **animal reservoirs** & resulted in the death of many **animals** as a control measure?
1. **Foot & mouth** disease
2. **Swine flu** disease - انفلونزا الخنازين
93
What do you know about **primary** pathogens?
* Primary pathogen: **a pathogen that always causes a disease**.
* They are never friendly, e.g.,
1. **mycobacterium tuberculosis**
2. **cholera**
94
What do you know about **opportunistic** pathogens?
* Opportunistic pathogens: **a pathogen that _sometimes_ causes a disease**.
* Examples:
1. **Staphylococcus aureus**
2. **E. Coli**
95
Where can you find the **normal flora/microbiota**?
Everywhere except the **brain** & **cerebrospinal fluid**
96
What is the **most common specimen to investigate** in the lab?
Urine
97
Does pathogenic organisms have **capsules**?
Pathogenic organisms have capsules,
while nonpathogenic don’t.
98
What do you know about microorganisms in the stomach & large intestine?
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.
