Microbial Biotechnology Midterm

Symbiosis

From Greek endo, meaning “inside,” and symbiosis, meaning “to live with”

• Mutualism

• Commensalilsm

• Parasitism

• Amensalism

Mutualism

both symbionts and hosts benefit

Ex: Human guts provide a moist environment and nutrients for gut microbiota and microbes provide vitamin precursor

Commensalism

One symbiont benefit without affecting the other

Ex: Staphylococcus aureus (S. aureus) is a commensal bacterium that can live on human skin without causing disease

Parasitism

Host is damaged while symbionts benefits

Ex: Mycobacterium tuberculosis in human lungs

Amensalism

One symbionts is harmed while second symbiont is unharmed/benefit

Microflora (microbiota)

Microbes that colonize the body without causing disease

______ protects fetus from microbes.

Amniotic membrane and fluid

Commensal organism

• an organism that lives in close association with another organism

• Microbes normally found at various nonsterile body sites

Resident microbiota

• A part of normal microbiota throughout life

• Mostly commensal

• Found on skin and mucous membranes (of the digestive tract, respiratory tract, distal portion of urethra, and vagina)

Transient microbiota

• Duration: 1 hour to months

• Found in the same regions as resident microbiota

• Cannot persist because:

  • Competition from other microorganisms

    • Transient outnumbered resident microbiota because of anitibiotics

  • Elimination by the body’s defense cells

  • Chemical or physical changes in the body

Upper Respiratory Tract Resident Microbiota

• Microbiota of the trachea and bronchi are sparse compared to those in nose and mouth

• Microbes in alveoli are axenic → no natural microbiota

Axenic microbe

a microbe that is grown in a culture free of other organisms

Upper Digestive Tract Resident Microbiota

• Microbes colonize surfaces of teeth, gingiva, lining of cheeks, and pharynx

• Microbes found in large number in saliva

• Dozens of unidentified microbes

Lower Digestive Tract Resident Microbiota

• Strictly anaerobes bacteria, while some facultative anaerobes are also resident

• Stomach bacteria love acidic enviroment

Female Urinary and Reproductive Resident Microbiota

• Microbiota changes based on the menstrual cycle because of acidity changes

• Urine flow prevents extensive colonization in urethra & bladder

Male Urinary and Reproductive Resident Microbiota

• Urine flow prevents extensive colonization in urethra & bladder

Eye & Skin Resident Microbiota

• Microbiota live in dead layers of the skin and hair follicles of the epidermis

• Microbiota in dermis and hypodermis are axenic

• Tears washes microbiota from eyes

_______ prevents microbial contamination and newborns get established their microbiota during ___ from their ___.

• Anemiotic fluid and placenta

• 1st month of life

• Environment (breathing, breast feeding, etc.)

Microbial antagonism

• The competition between normal microbes and pathogens for nutrients and space

• Reinforces the body’s defense by limiting the ability of pathogens to colonize the skin and mucous membranes (synthesizing antimicrobial compound)

Commensal bacteria

Microorganisms that live on the body's surfaces without causing harm and can enhance immune system

____ can protect against colorectal cancer by activating ____

• Enterotoxin

• Enterotoxin acts as a superantigen that triggers massive activation of T cells →increase in intracellular calcium levels

Changes in normal microbiota are caused by:

• Long-term antimicrobial therapy

• Hormonal changes

• Stress

• Change in diet

• Exposure to overwhelming number of pathogens

Immune suppression are caused by

• Diseases

• Malnutrition

• Emotional or physical stresses

• Extreme of age (very old or young)

• Usage of radiation or chemotherapy

• Immunosuppressive drugs in transplants

Reservoir of Infection

Sites where pathogens are maintained as a source of infection

Human carriers

Humans who harbor and transmit a pathogen—often without symptoms (asymptomatic) or after recovery (convalescent carriers).

Animal reservoir

Animals that naturally harbor a pathogen, often without showing symptoms, and serve as a long-term host.

Zoonoses

Diseases that are naturally spread from their usual animal host (either domesticated or sylvatic) to humans

True/False: Humans are usually dead-end host to zoonotic pathogens

True.

This is true because humans often do not transmit diseases to animals because human waste is clean of pathogens in the body, and not many animals feed on human carcasses.

Why are zoonoses hard to eridicate?

Zoonoses are difficult to eradicate because of the extensive amount of hosts that are involved in the progressed. This is even more costly if there is a large human-to-reservoir contact and a mass amount of reservoir.

Another factor that should be noted is that if the animal has a similar physiology to humans, then the zoonoses would have a greater impact on the human body.

Nonliving Reservoirs

Inanimate objects or environments (abiotic factor) where pathogens can survive and potentially infect humans or animals

Contamination

The mere presence of the microbes in or on the body and these microbes can either be resident or transient microbiota

Infection

The invasion and growth of germs once they have been established in the body. It should be noted that most infection goes unnoticed so an infection does equal disease.

Infection cycle

Steps that note the infection process from when the pathogen/parasite enters or begins to grow to when it spreads to another host.

Fomites (= fomes)

Inanimate objects through which pathogens can be relayed to host

Vectors

Animate objects, such as insects, serve to carry infectious agents from one animal to another

Reservoir

An animal, bird, or insect that normally harbors the pathogens. Reservoirs are critically important for the survival of a pathogen and as a source of infection

What are examples of contact transmission? What are some disease that are spread by the transmission?

• Direct contact: Hand shaking, kissing, sex, biles

  • Cutaneous anthrax

  • Genital warts

  • Herpes

• Indirect contact: Shared items such as glass, toothbrushes, toys, etc

  • Common cold

  • Enterovirus infections

  • Influenza

• Droplet transmission: Droplets from sneezing from within 1 meter

  • Whooping cough

  • Streptococcal pharyngitis

What are examples of vehicle transmission? What are some disease that are spread by the transmission?

• Airborne: dust particles or droplets carried within 1 meter

  • Chickenpox

  • Pulmonary anthrax

  • Tuberculosis

• Waterborne: streams, swimming pools

  • Campylobacter infections

  • Cholera

  • Giardia diarrhea

• Foodborne: Poultry, seafood, meat

  • Botulism

  • Typhoid fever

  • Tapeworms

What are examples of vector ransmission? What are some disease that are spread by the transmission?

• Mechanical: on bodies of flies, roaches

  • E. coli

  • Trachoma

• Biological: lice, mites, mosquitoes, ticks

  • Chagas’ disease

  • Malaria

  • Plague

Biological vectors

• Transmit pathogens

• Hosts for the multiplication of a pathogen during some stage of pathogen’s life cycle

• Typically biting arthropods (mosquitoes, ticks, fleas, bloodsucking flies and bugs, mites, etc.)

Mechanical vectors

• Just transmit pathogens

• Not hosts for the pathogens: passively carrying pathogens to new hosts on their feet or other body parts

What are the four major pathways of Portals of Entry?

1. Skin

2. Mucous membrane

3. Placenta

4. Parental routes

Portal of entry: Skin

• Outer layer of packed, dead, skin cells usually acts as a barrier to pathogens because they provide no nutrition

• Some pathogens can enter through openings or cuts

• Others enter by burrowing into or digesting the outer layers of skin

Portal of entry: Mucous membranes

• Line the body cavities that are open to the environment

  • Respiratory, gastrointestinal, urinary, and reproductive tracts, and conjunctiva

• Provide a moist, warm environment that is hospitable to pathogens

• Respiratory tract is the most common site of entry - entry is through nose, mouth, and eyes

• Pathogens able to survive the acidic pH of the stomach may use the gastrointestinal tract as a route of entry

Portal of Entry: Placenta

• Typically are effective barrier to most pathogens (<2% of pregnancy, pathogens can cross the placenta and infect embryo or fetus)

• Some pathogens that can cross the placenta are:

  • Toxoplasma gondii

  • Treponema pallidum

  • Rubivirus

  • Parovirus B19

Portal of Entry: Parenteral route

• Not a true portal of entry but a means by which the portal of entry can be circumvented

• Pathogens deposited into tissues beneath the skin or mucous membranes

True/False: Many portals of exits are the same as portals of entry

True. Pathogens often leave hosts in materials in the body that secrete or excrete

Disease

• Invading pathogen that alters the normal functions of the body

• Referred to as morbidity

____ are subjective characteristics of disease gelt only by the patient and ___ are objective manifestations of diseases that can be observed or measured by others

Symptoms; Sign

Syndrome

A group of symptoms and signs that are characterize a disease or abnormal conditions

Asymptomatic/ sub-clinical

Infections that lack symptoms but may still have signs of infection

carcino-

• cancer

• carcinogenic: giving rise to cancer

col-, colo-

• colon

• colitis: inflammation of the colon

dermato-

• skin

• dermatitis: inflammation of the skin

-emia

• pertaining to the blood

• viremia: viruses in the blood

endo-

• inside

• endocarditis: inflammation of the lining of the heart

-gen, gen-

• give rise to

• pathogen: giving rise to disease

hepta-

• liver

• hepatitis: inflammation of liver

idio-

• unknown

• idiopathic: pertaining to a disease of unknown cause

-itis

• inflammation of a structure

• meningitis: inflammation of the meninges ( a thin layer that surrounds the brain

• endocarditis: inflammation of the endocardium

-oma

• tumor or swelling

• papilloma: wart

-osis

• condition of

• toxoplasmosis: being infected with Toxoplasma

-patho, patho-

• abnormal

• pathology: study of disease

septi-

• literally rotting; refers to presence of pathogens

• septicemia: pathogens in the blood

terato-

• defects

• teratogenic: causing birth defects

tox-

• poison

• toxin: harmful compund

Etiology

the study of cause, set of causes, or manner of causation of a disease or condition

What are the categories of diseases?

• Hereditary

• Congenital

• Degenerative nutrional

• Endocrine (hormonal)

• Mental

• Immunological

• Neoplastic (humor)

• Infectious

• Idiopathic

• Nocosomial

Hereditary disease

Disease caused by errors un re genetic codes received form parents

Ex: Sickle-cell anemia

Congenital disease

Anatomical and physiological (structural and functional) defects present at birth; caused by drugs (legal and illegal), X-ray exposure, and infections

Ex: Fetal alcohol syndrome

Degenerative disease

Result from aging

Ex: Renal failure

Nutritional disease

Result from a lack of some essential nutrients in diet

Ex: Kwashiorkor

Endocrine (hormonal) disease

Due to excesses or deficiencies of hormones

Ex: Dwarfism

Mental disease

Emotional or psychosomatic

Ex: Skin rash

Immunological disease

Hyperactive or hypoactive immunity

Ex: Allergies

Neoplastic (tumor) disease

Abnormal cell growth

Ex: Benign tumors

Infectious disease

Caused by an infectious agent

Ex: Colds

Iatrogenic disease

Caused by medical treatment or procedures; are a subgroup of hospital-acquired diseases

Ex: Surgical error

Idiopathic disease

Unknown cause

Ex: Alzheimer’s disease

Nosocomial disease

Disease acquired in health care setting

Ex: Pseudomonas infection

Germ theory of disease

• Disease caused by infection of pathogenic microorganisms

• Proposed in the 19th century by Louis Pasteur

Koch’s Postulate

1) be present in all cases of the disease

2) be isolated from diseased patients

3) cause disease when reintroduced to a healthy susceptible animal model

4) then be isolated again from the new host.

When are the Koch’s postulates exception?

• Some pathogens are unculturable in the laboratory

• Some diseases are caused by a combination of pathogens and some other cofactors

• Ethical considerations prevent applying Koch’s postulates to pathogens that require a human host

• Some diseases that can be cause by more than one pathogen

What are the stages of infectious disease?

1. Incubation period

   1. Time between infections and first symptoms

   2. Determined by virulence, infectious dose, health of host, nature of pathogen, its generation, and site of infection

2. Prodromal period

   1. A short time of generalized, mild symptoms (optional)

3. Illness

   1. The most severe stage (highest peak) of an infectious disease

   2. Signs and symptoms are most evident

   3. Typically host immune system has not yet fully responded

4. Decline

   1. Body gradually returns to normal with highest immune response

5. Convalescence

   1. The patient recovers from illness

How can diseases can be classified?

1. Taxonomic groups of causative agent

2. Body system they affect

3. Longevity and severity

4. How they are spread to their host

5. Effect on population

Acute disease

Disease in which symptoms develop rapidly and that runs its course quickly

Chronic disease

Disease with usually mild symptoms that develop slowly and last a long time

Subacute disease

Disease with time course and symptoms between acute and chronic

Asymptomatic disease

Disease without symptoms

Latent disease

Disease that appears a long time after infection

Communicable disease

Disease transmitted from one host to another

Ex: Leprosy

Contagious disease

Communicable diseases that are easily spread are typically spread via droplets or airborne

Ex: COVID

Noncommunicable diseases

Disease arising from outside of host or from opportunistic pathogen

Local infection

Infection confined to a small region of the body

Systemic infection

Widespread infection in many systems of the body; often travels in the blood or lymph

Focal infection

A form of localized infection that serves as source of pathogens for infections at other sites in the body

Primary infection

Initial infection within a given patient

Secondary infection

Infections that follow a primary infections; often by opportunistic pathogens

Epidemiology

The study of where and when diseases occur and how they are transmitted within a population

How are disease track?

• Incidence - number of new cases of a disease in a given area during a given period of time

• Prevalence - number of total cases of a disease in a given area during a given period of time