Micro Lab week 9

what is contact transmission

provides a route for pathogenic microbes to move from an infected source (such as a reservoir or infected host) to a susceptible host

contact transmission can occur via (3)

direct contact, indirect contact, or droplet exchange.

The individual that initiates the transmission of disease is referred to as the

index case

direct contact is when

A pathogen spreads through physical contact between an infected person and another person

indirect contact is when

A pathogen spreads through a contaminated object or surface, also called a fomite.

droplet exchange is when

Respiratory droplets containing pathogens travel from an infected person to another person, usually during coughing, sneezing, or talking.

How does the droplet transmission exercise simulate a sneeze/cough?

The aerosol generator (plant mister) simulates a person sneezing or coughing by releasing tiny droplets containing bacteriophage T2 into the air. The droplets can travel through the air and land on exposed agar plates. By counting the plaques that form on the plates, we can estimate how many viral particles were present in the air and determine how long the virus remains airborne

Identify the susceptible host and the transmitted microbe in the cough simulator

• Susceptible host: Escherichia coli B (E. coli B), the bacteria that the virus infects.

• Transmitted microbe: Bacteriophage T2, a nonpathogenic virus that infects and destroys E. coli B

Define plaque

A plaque is a clear zone in a bacterial lawn caused by the destruction (lysis) of bacterial cells by bacteriophages. Each plaque represents one viral particle

Define virulent bacteriophage.

A virulent bacteriophage is a virus that infects bacteria and causes them to lyse (burst open), releasing new viruses. It follows the lytic cycle

Immune-compromised patients have an increased susceptibility to ___ that may be present in a healthy individual’s intestinal flora

opportunistic pathogens

Hand hygiene is important because it

removes or kills microbes and helps prevent the transmission of pathogens that can cause infections

A breach in hand hygiene, such as failing to wash hands after using the restroom or touching a contaminated surface (fomite), can

transfer microbes to patients through direct or indirect contact. Microbes that are harmless in a healthy person’s normal intestinal flora can cause serious infections in immunocompromised individuals

Washing with water alone removes some microbes through

mechanical distribution

washing with regular soap and water combines a ___ with ___

surfactant; mechanical distribution

surfactants consist of a ____ end and a ___ end

hydrophobic; hydrophilic

The___ end attaches to oily deposits that contain bacteria and viruses

hydrophobic

the ___ end is attracted to water molecules, allowing the oily deposits to be washed away

hydrophilic

Washing your hands with soap and water is an example of

degerming

what is degerming

microbes are removed but otherwise left unharmed

what is the mode of action for hand washing with water only

mechanical distribution

what is the mode of action for hand washing with soap and water

surfactant and mechanical distribution

what is the mode of action for hand washing with antimicrobial soap

surfactant, antimicrobial chemical, and mechanical distribution

what is the mode of action for hand washing with hand sanitizer

alcohol disrupts the cell membrane

what is hemolysis

the lysis of red blood cells (RBCs) before the end of their normal life span.

Hemolytic activity can be observed by culturing bacteria on

blood agar

Blood agar is a type of ___ medium that distinguishes organisms based on their ability to ___

differential; lyse RBCs

what are the three types of hemolysis

alpha, beta, gamma

what is alpha hemolysis

the result of a partial breakdown of RBCs and results in a greenish halo

what is beta hemolysis

a complete breakdown of RBCs that results in a clear halo surrounding the bacterial colony

gamma hemolysis is when

an organism is unable to lyse RBCs

what is cytolytic activity

the ability to lyse any cell—not just a red blood cell