Unit 3.1

Some bacteria enter phagocytic cells but are not killed by the phagocyte. Why might this be?

- They use a type 3 secretion system to secrete effector molecules that prevent the phagosome from fusing with the lysosome -Once engulfed, they kill the phagocytic cell by inducing apoptosis

State at least 3 benefits associated with bacteria living as a community within a biofilm

-resist attack by antibiotics; -trap nutrients for bacterial growth and remain in a favorable niche; -adhere to environmental surfaces and resist flushing; live in close association and communicate with other bacteria in the biofilm; -resist phagocytosis and attack by the body's complement pathways.

List 6 virulence factors that promote bacterial colonization of the host

1. The ability to use motility and other means to contact host cells and disseminate within a host. 2. The ability to adhere to host cells and resist physical removal. 3. The ability to invade host cells. 4. The ability to compete for iron and other nutrients. 5. The ability to resist innate immune defenses such as phagocytosis and complement. 6. The ability to evade adaptive immune defenses

Briefly describe 3 different mechanisms by which bacteria can adhere to host cells and colonize and state how this can promote colonization

1. Using pili 2. Using adhesins 3. Using biofilm

List 4 requirements for a microorganism to cause infectious disease

1.Maintain a reservoir before and after infection 2. Leave the reservoir and gain access to the new host 3. Adhere to cells of the skin or mucosa of its new host and colonize the body 4. Harm or damage the body

symptom

A condition experienced and reported by the patient.

Briefly describe how a type 3 secretion system might be used to invade and survive inside host cells

A type 3 secretion systems enable a number of bacteria to inject effector proteins, in this case invasins, that cause the host cell to engulf the bacterium and place it in an endosome or phagosome. Here it has ready access to nutrients and can resist many defense cells and defense chemicals. It might also inject effector proteins that prevent lysosomes from fusing with the phagosomes creating a safe haven for the bacterium

disease

An abnormal condition of an organ or other part of an organism resulting from the effect of genetic or developmental errors, infection, nutritional deficiency, toxicity, or unfavorable environmental factors

zoonosis

An infectious disease that is transmissible under natural conditions from vertebrate animals to humans

Vectors

An organism such as an insect that transmits a pathogen from one organism or source to another

vector

An organism such as an insect that transmits a pathogen from one organism or source to another.

Describe specifically how certain bacteria are able to use motility to contact host cells and state how this can promote colonization

As the biofilm begins to get too crowded with bacteria, quorum sensing enables some of the Pseudomonas to again produce flagella, escape the biofilm, and colonize a new location

How do invasins help bacteria to colonize the body?

By enabling bacteria to enter host cells

Most bacteria that invade cells do so by which means?

By secreting invasins that trick the host cell into engulfing the bacterium.

__________ is where there is impairment to host function as a result of damage or injury

Disease

Airborne transmission

infectious agents are carried by dust or droplets suspended in air

Bacteria can resist body defense chemicals and more effectively compete for nutrients by:

invading host cells.

Give a brief description of how a bacterium may use toxins to better disseminate from one host to another

many bacteria produce enzymes such as elastases and proteases that degrade the extracellular matrix proteins that surround cells and tissues and make it easier for those bacteria to disseminate within the body

Match Neisseria memingitidiswith the description of the organism and the infection it cause

meningitis meningococcemia pneumonia

Read the description of Salmonella

moderately-sized Gram-negative bacilli. Possess a peritrichous (def) arrangement of flagella. Facultative anaerobes

Read the description of Shigella

moderately-sized, non-motile, Gram-negative bacilli. Facultative anaerobes

Match Salmonella with the description of the organism and the infection it causes

salmonellosis Enteritis bacteremia

Most bacteria that invade cells do so by:

secreting invasins that trick the host cell into engulfing the bacterium.

Match Shigella with the description of the organism and the infection it causes

shigellosis S. dysenteriae, S. flexneri, S. boydii, and S. sonnei

A(n) _________ is an objective indication of some medical fact or characteristic that may be detected by a healthcare professional during a physical examination. A(n) _________ is a condition experienced and reported by the patient.

sign; symptom

Read the description of Borrelia bergdorferi and match the bacterium with the description of the organism and the infection it causes

spirochete 0.2 to 0.5µm X 3-30µm that can be seen by Giemsa or Wright staining. Microaerophilic

State an advantage for bacteria in being able to switch the adhesive tips of their pili

the same bacterium may switch the adhesive tips of the pili in order to adhere to different types of cells and evade immune defenses

Direct contact

through skin-to-skin contact, kissing, and sexual intercourse. Examples include some Staphylococcus aureus infections, infectious mononucleosis, and gonorrhea

Inanimate objects

water, food, blood, and fomites (inanimate objects such as toys, handkerchiefs, bedding, or clothing). Examples include cholera, salmonellosis, listeriosis, viral hepatitis).

_________ is when a microorganism has established itself in a host - has colonized that host - whether not it causing harm or imparting damage.

infection

Indirect transmission

Infectious agent from a reservoir to a host by suspended air particles, inanimate objects, or vectors.

Bacteria can resist body defense chemicals and more effectively compete for nutrients by which of the following means?

Invading host cells

infection

Invasion by and multiplication of microorganisms in a bodily part or tissue, which may or may not produce subsequent tissue injury and progress to overt disease

Match Borrelia bergdorferi with the description of the organism and the infection it causes

Lyme disease meningitis myopericarditis

Give one example of how a nonmotile bacterium may be able to better disseminate within a host

Many bacteria produce enzymes such as elastases and proteases that degrade the extracellular matrix proteins that surround cells and tissues and make it easier for those bacteria to disseminate within the body

Why might motility aid bacteria in colonizing the body?

Motile bacteria can use motility and chemotaxis to swim through mucus towards mucosal surfaces

Why might motility aid bacteria in colonizing the body?

Motile bacteria can use motility and chemotaxis to swim through mucus towards mucosal surfaces.

Briefly describe why being extremely thin and being motile by means of axial filaments may be an advantage to pathogenic spirochetes

Motility and penetration may also enable the spirochetes to penetrate deeper in tissue and enter the lymphatics and bloodstream and disseminate to other body sites

State why it might be of an advantage for a bacterium trying to colonize the bladder or the intestines to be motile

Motility probably helps these bacteria move through the mucus between the mucin strands or in places where the mucus is less viscous

_____________ is the ability of a microbe to cause disease and inflict damage upon its host, whereas ____________ is the degree of pathogenicity within a group or species of microbes

Pathogenicity; virulence

pathogenicity

The ability of a microbe to inflict damage upon its host

virulence

The degree of pathogenicity within a group or species of microbes as determined by its virulence factors

reservior

The habitat in which that microbe normally lives, grows, and multiplies. Reservoirs can include humans, animals, and the environment.

etiologic agent

The microorganism causing an infectious disease

portal of exit

The microorgansim must leave its reservoir or host through

portal of entry

The portal of entry must provide access to tissues with the correct physical and chemical environment

State how certain pathogenic spirochetes such as Borrelia bergdorferi use adhesins, invasins and motility to penetrate host cells.

The tip of the spirochete Borrelia burgdorferi contains adhesins that can bind to various host cells.

State how certain pathogenic spirochetes such as Treponema pallidum use adhesins, invasins and motility to penetrate host cells

The tip of the spirochete Treponema pallidum contains adhesins that are able to bind to fibronectin on epithelial cells.

What might be a way non-motile bacteria might spread through the body?

They might produce enzymes such as proteases that degrade the extracellular matrix proteins that surround cells and tissues and make it easier for those bacteria to spread within the body

T/F The symbiotic relationship between humans and their natural microbes is critical to good health.

True

Match Helicobacter pylori with the description of the organism and the infection it cause

gastritis peptic ulcers gastric adenocarcinoma b-cell lymphomas

Direct droplet contact

In the case of aerosols produced by sneezing and coughing. Examples include memingococcal infections and pertussis (whooping cough).

T/F If a pathogenic bacterium enters the body, the person will most likely develop an infectious disease

False

T/F Most bacteria are harmful to humans

False

Briefly describe a mechanism by which invasins enable certain bacteria to enter host cells

Some bacteria a type 3 secretion system to inject effector molecules called invasins that activate the cytoskeletal machinery of the host cell enabling bacterial entry into the cell by phagocytosis. By entering the cytoplasm of the host cell, it has a ready supply of nutrients and is able to protect the bacteria from complement, antibodies, and certain other body defenses

sign

Some medical fact or characteristic that may be detected by a healthcare professional during a physical examination

Which of the following bacteria use motility by way of their axial filaments to enter capillaries and disseminate via the lymphatics and the blood

Spirochetes such as Treponema pallidum and Borrelia bergdorferi

__________ use motility by way of their axial filaments to enter capillaries and disseminate via the lymphatics and the blood.

Spirochetes such as Treponema pallidum and Borrelia bergdorferi

Invasins help bacteria to colonize the body by:

enabling bacteria to enter host cells

virulence factors

Virulence factors are molecules expressed and secreted by that enable them to colonize the host, evade or inhibit the immune responses of the host, enter into or out of a host cell, and/or obtain nutrition from the host

Even though a microorganism may be considered pathogenic, it still may not be able to cause disease upon entering the body. Discuss why

Whether or not a person actually contracts an infectious disease after exposure to a particular potentially pathogenic bacterium depends not only on the microorganism but also on the number of bacteria that enter the body and the quality of the innate and acquired body defenses of the person involved.

Read the description of Neisseria memingitidis

a Gram-negative diplococcus, typically flattened where the cocci meet, Aerobic

Read the description of Helicobacter pylori

a gram-negative spiral-shaped bacterium with polar flagella, Microaerophilic