Microbiology Test 3 Study Guide

This is a comprehensive review of all material that will be on Test 3

Endogenous infection:

An infection caused by microorganisms that are already present in the body’s normal flora

Exogenous infections:

An infection that is acquired from an external source, such as another person, animal, or contaminated environment

Exotoxins:

Poisonous proteins secreted by bacteria into the surrounding environment

Endotoxins:

Toxic lipopolysaccharide molecules found in the outer membrane of gram-negative bacteria; they are released when the bacterial cell dies or ruptures

Signs:

• Observable and measurable by a healthcare professional

• Objective evidence of a disease

• Examples: fever, rash, visible swelling, elevated blood pressure

Symptoms:

• Reported by the patient and subjective in nature

• Cannot be directly observed by a healthcare professional

• Examples: pain, headache, nausea, fatigue

Serotypes:

Bacterial subgroups

Serotyping:

Antigen-antibody technique for identifying, classifying and subgrouping bacteria into serotypes; employs antisera against cell antigens such as the capsule, flagellum , and cell wall

Sequelae:

Pathological or chronic conditions that persist after a previous disease, injury, or trauma has resolved

Examples of sequelae pathogens:

• Chickenpox: can remain dormant in nerve cells, reactivating to cause shingles

• HPV: causes persistent infections that can lead to cervical cancer

• Polio: can cause permanent neurological damage

Infectious Dose 50 (ID50):

The amount of a pathogen needed to cause infection in 50% of an exposed population; a lower ID50 value indicates a more infectious pathogen, while a higher ID50 suggests that a larger dose is required to cause an infection

Florence Nightingale:

Early nurse that observed firsthand that soldiers were dying from preventable infections; started using strict sanitation and collected data that supported the fact that poor sanitation was the main cause of death at the battlefield

Robert Koch:

German physician and microbiologist, identified the specific microbes that cause anthrax, tuberculosis, and cholera; also created Koch’s postulates that establish a relationship between microbe and disease

John Snow:

British physician and pioneer in epidemiology and anesthesia, best known for investigating cholera outbreak in London by mapping cases and tracing them to a contaminated water pump; also championed the use of anesthesia

Protective mechanisms of the skin:

• Physical and chemical barrier: outermost layer of epidermis prevents the entry of microbes, and oils on the skin contain lipids and proteins that kill bacteria

• Sweat is used to cool, and shivering is used to heat

• Nerves act as a warning system to prevent injury

• Immune cells are located in the skin and are constantly patrolling for germs and other invaders

What blood cells are commonly present during parasitic infections and allergic reactions?

Eosinophils and basophils are the primary white blood cells present; eosinophils release toxic proteins to damage the parasite and basophils release substances that contribute to the symptoms of the allergy

What is a phagocytic white blood cell that is most numerous in the blood?

Neutrophils

Where do T cells mature?

In the thymus

What are interferons?

Proteins produced by the immune system in response to viral infections or other cellular stresses

What is involved during the complement cascade when bacteria are involved?

Three distinct pathways can be activated: classical, lectin, and alternative. All three converge to clear the infection by labeling the bacteria for destruction, attracting immune cells to the area, and directly killing the bacteria by causing cell lysis

What activates the classical complement pathway?

IgG or IgM antibodies that have bound to a target

What is involved in acquired specific immunity?

Lymphocytes (B and T cells) that recognize specific invaders, or antigens, and develop a “memory” to fight them more efficiently in the future

What do helper T-cells do?

Coordinate the immune response by activating other immune cells, such as B cells and cytotoxic T cells, using chemical signals called cytokines

What do plasma cells do?

White blood cells that produce and secrete antibodies

What is the function of the histocompatibility complex?

To present antigens on the surface of cells to T cells, helping the immune system distinguish between the body’s own cells and foreign invaders

What are the immunoglobulin classes?

IgD, IgE, IgA, IgG, IgM

What is IgD?

Found on the surface of B cells, it plays a role in initiating the immune response

What is IgE?

Primarily involved in allergic reactions and reactions against parasitic worms

What is IgA?

Primarily found in mucosal secretions like tears, saliva, and breast milk, it protects the body from pathogens at mucosal surfaces; has two subclasses

What is IgG?

The most abundant immunoglobulin in human serum, it is the main antibody in the blood and can cross the placenta; has four subclasses

What is IgM?

The first antibody produced during an immune response, found in the blood and lymph fluid

What is the purpose of clonal expansion?

Allows the immune system to rapidly create a large army of identical immune cells that are specific to a particular pathogen, enabling a strong and effective defense

What are all of the types of white blood cells?

Lymphocytes, neutrophils, monocytes, basophils, eosinophils

Neutrophils:

Most abundant type of WBC, fight bacterial and fungal infections, and release enzymes that kill pathogens

Lymphocytes:

Subdivided into T cells, B cells, and natural killer (NK) cells

T cells:

Recognize and destroy infected cells and cancer cells

B cells:

Produce antibodies that neutralize pathogens

NK cells:

Kill virus-infected cells and tumor cells

Monocytes:

Transform into macrophages, which engulf and destroy pathogens, dead cells, and debris; play a role in inflammation and wound healing

Eosinophils:

Fight parasitic infections, involved in allergic reactions, and release chemicals that reduce inflammation

Basophils:

Release histamine and heparin in response to allergens; play a role in allergic reactions and blood clotting

What do cytotoxic T cells and NK cells do?

Both are immune cells that kill infected or cancerous cells. However, the cytotoxic T cells are part of the adaptive immune system providing a slower but more specific response, while the NK cells are part of the innate immune system that provide a rapid non-specific first line of defense

What can be used to serotype a bacterium?

• Antisera

• Slide agglutination test

• Phage typing

• Polymerase chain reaction

• Whole-genome sequencing

Antisera:

Prepared antibodies that target specific bacterial surface antigens, such as heat-stable O (cell wall) and heat-labile H (flagellar) antigens

Slide agglutination test:

Mixing a bacterial suspension with a specific antiserum to observe a visible clumping reaction, indicating a math

Phage typing:

Using a set of bacteriophages to determine the susceptibility pattern of a bacterial isolate

Polymerase chain reaction:

Using primers that amplify serotype-specific genes to rapidly and accurately identify a serotype

Whole-genome sequencing:

Analyzing the entire bacterial genome to identify serotype-specific genes and single nucleotide polymorphisms

What does it mean by One Health?

An approach that emphasizes the importance of collaborating across sectors to optimize health outcomes for all three components of the One Health Triad: human health, animal health, and environmental health

What happens during eutrophication?

1. Nutrient input: nutrients enter the water body through various sources

2. Algal growth: the increased nutrients stimulate the growth of algae

3. Algal bloom: The algal bloom forms a dense layer on the water surface, blocking sunlight from reaching deeper water layers

4. Oxygen depletion: as the algae die and decompose, bacteria consume oxygen in the water leading to low oxygen levels

5. Loss of biodiversity: the lack of oxygen and presence of toxic algae cause the death of many aquatic organisms

6. Dead zone formation: In severe cases, can create large areas of water with extremely low oxygen levels where no life can survive

True pathogen:

An infectious agent that can cause disease in a healthy individual, regardless of their immune status

Opportunistic pathogen:

A microorganism that normally lives in the body without causing disease but can become pathogenic when the host’s immune system is weakened

Phagocytosis:

The process by which a cell engulfs and ingests large particles, such as pathogens or cellular debris, to form a vesicle called a phagosome

Asymptomatic:

Producing or showing no symptoms

Secondary infection:

An additional infection that occurs after an initial infection has weakened the body’s immune system

Non-communicable:

Chronic diseases that are not transmitted from person to person infection

Opsonization:

An immune process where pathogens or other particles are “tagged” with molecules called opsonins, to mark them for destruction

Denitrification:

A biological process where bacteria convert nitrates into nitrogen gas, which is then released into the atmosphere

Specificity:

A diagnostic test’s ability to correctly identify individuals who do not have the disease or condition; a high specificity means the test is great at correctly identifying unaffected individuals

Inflammation:

A biological process that occurs when the body’s immune system responds to an injury, infection, or other harmful stimulus

Vector:

A living organism that transmits a pathogen from one host to another

Aerosol:

A suspension of fine solid or liquid particles in a gas, typically air

Mortality:

The number of deaths within a population over a specific time

Herd immunity:

Resistance to the spread of an infectious disease within a population that is based on pre-existing immunity of a high proportion of individuals as a result of previous infection or vaccination

Antigen:

A substance that your immune system recognizes as foreign and that triggers an immune response to fight it off; acts as a foreign marker on things like bacteria, viruses, toxins, or other substances, signaling the body to defend itself

Nitrification:

A two-step biological process where bacteria convert ammonia (NH4+) first into nitrite (NO2-) and then into nitrate (NO3-).

Agglutination:

The clumping of cells or particles, such as red blood cells or bacteria, into larger masses

Microbial ecology:

The study of microorganisms, how they interact with their environment, and their relationships with one another

Subclinical:

Relating or denoting a disease which is not severe enough to present definite or readily observable symptoms

Biological vector:

An organism that is infected with a pathogen, and the pathogen undergoes a part of its life cycle within the vector’s body before being transmitted to a new host

Mechanical vector:

An organism that carries pathogens on its body from one location to another without being infected itself

Epidemiology:

The branch of medicine which deals with the incidence, distribution, and possible control of diseases and other factors relating to health

Morbidity:

The amount of disease within a population

Communicable:

Able to be transmitted from one sufferer to another; contagious or infectious

Antibody:

A protein produced by the immune system in response to the presence of a foreign substance

Nitrogen fixation:

The process of converting atmospheric nitrogen gas into a usable form, such as ammonia.

Precipitation:

Any form of water that falls from the atmosphere to Earth’s surface

Biotechnology:

The use of living organisms, biological systems, or their components to create or modify products and technologies

Fomite:

Objects or materials which are likely to carry infection, such as clothes, utensils, and furniture

Incidence:

The rate at which new cases of a particular event or condition occur in a population over a specific period of time

Prevalence:

A measure of how common a disease, condition, or characteristic is within a specific population at a given time

Lysozyme:

An enzyme that works by breaking down the cell walls of bacteria, specifically targeting the peptidoglycan layer; present in tears, saliva, mucus, and breast milk

Epitope:

The specific part of an antigen that an antibody or T-cell recognizes and binds to, also known as an antigenic determinant

Rhizosphere:

The narrow zone of soil that is directly influenced by root secretions and associated soil microbes

Sensitivity:

An organism’s susceptibility to a particular antimicrobial drug

Bioterrorism:

Intentionally releasing viruses, bacteria, or toxins to harm people, livestock, or crops; the most likely agent for such attacks is Bacillus anthracis