Unit 2 microbiology

What do HIV’s surface proteins recognize on the helper T cells?

CD4 receptor

What is HIV know to cause?

AIDS

what is AIDS

it destroys certain immune cells and leaves patients vulnerable to many infections that can quickly become deadly.

What is hyphae

A long, threadlike filaments that make up the body of a fungus

What is the difference of vegetative and aerial hyphae

• Vegetative: obtain nutrients

• Aerial: involved with reproduction

What is the difference of budding and fission yeast

Budding: divide unevenly

Fission: divide evenly

What is mitosis

the process where a cell divides to produce 2 identical daughter cells with the same DNA as the original cell

List the type of asexual spores produced by fungi:

• Conidiospore: not enclosed in a sac
• Arthroconidia: fragmentation of septate hyphae
• Blastoconidia: buds of the parent cell
• Chlamydoconidium: spore within a hyphal segment
• Sporangiospore: enclosed in a sac

What are the 3 phases of sexual reproduction of fungi

1. Plasmogamy: haploid donor cell nucleus penetrates the cytoplasm of recipient cell

2. Karyogamy: + and - nuclei fuse and form diploid zygote

3. Meiosis: diploid nucleus produces haploid nuclei
   (sexual spores)

Are spores resistant to heat and radiation?

No

Are bacterial endospores reproductive?

No

What pH do fungi like to grow at?

pH 5 (more acidic)

Are molds anaerobic or aerobic?

aerobic

Are yeast facultative anaerobes?

Yes

What type of environment do fungi survive

• High sugar and salt concentration

• Tolerant to high osmotic pressure

Do fungi like low or high mositure

low

What is the difference between sterilize and sterile?

• Sterilize: killing or removing all microbes

• Sterile: no living organisms present

What does disinfect mean

• Reducing the number of pathogenic organisms to the point that there is no threat of disease.

• Not the same thing as sterile.

• Doesn’t usually kill endospores/spores

What is the difference between disinfectant and antiseptic

• Disinfectant: chemicals used to disinfect inanimate objects

• Antiseptic: chemicals that can be used to safely disinfect living tissues

What are the physical agents of microbial control?

• Heat: Uses moist or dry heat to kill
• Filtration: Used for liquid and some gases
• Low temperature: Freezing prevent bacterial growth but doesn’t necessarily kill bacteria
• High pressure: Pressure can alter protein structure and inactivate vegetative cells. Pressure alone rarely enough to kill endospores
• Desiccation: Extreme drying or the removal of moisture
• Osmotic pressure: Uses high concentration of salt to preserve foods. Prevents bacterial cells from obtaining moisture.
• Radiation: Energy that travels through space as waves.

What is the difference between ionizing radiation and non-ionizing radiation.

• Ionizing: uses high energy wavelengths (gamma rays, x-rays, electron beams) to damage DNA, killing microbes. Used for medical supplies.

• Non-ionizing: Uses lower energy (UV light, visible light, microwaves). Create thymine dimers that inhibit DNA replication

What are surface active agents (surfectants)

• helps remove microbes from surfaces

What is etiology?

the cause of disease

what is pathogenesis?

the way a disease develops

What is infection?

the invasion or colonization of the body by pathogenic microorganisms

What is disease?

an abnormal state; when and infection results in a change in health

What are symptoms?

subjective changes in body function. Something that is experienced by the patient but not directly observable. Observed internally

• Headache

• Fatigue

• Vomiting

What are signs?

Objective changes in the body function. These can be measured externally.

• Fever

• Swelling

• Sores

• heart rate

What is a syndrome?

A collective group of signs and symptoms that accompany some disease

What does infectious mean?

A pathogenic organism is capable of producing an infection

What does communicable mean? What does noncommunicable mean?

• A disease that can be transmitted from person to person

• Is not spread between hosts, must be introduced to the body some other way

What does contagious mean?

a disease that is transmitted very easily from person to person

What does fomite mean?

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

What is the difference in acute, chronic, subacute, and latent disease?

• Acute: develops rapidly, last a short time. Ex: flu, colds, etc

• Chronic: develops slowly, continues or reoccurs for a long period, may never resolve. Ex: hepatitis, TB, HIV

• Subacute: last longer than an acute disease but is not considered chronic. Ex: endocarditis, meningitis, etc..

• Latent: varicella zoster (chickenpox/shingles) and herpes simplex

What is the difference in the different types of infection?

• Local: Microbes limited to a small area of the body (a boil)

• Systemic: generalized infection where microbes are spread throughout the body/multiple body systems (measles)

• Focal: When a local infection spreads but is still confined to specific areas of the body, can become systemic. (strep throat→scarlet fever)

What is spesis?

Toxic inflammatory condition that occurs when microbes spread beyond their focus of infection. Caused by LPS from gram negative bacteria

What is Septicemia?

pathogens enter the blood and spread throughout the body

What is bacteremia?

bacteria in the blood

What is toxemia?

toxins produced by pathogens enter the bloodstream

What is viremia?

Viruses in the blood

What is the difference between primary, secondary, and subclinical infections

Primary: Acute infection, initial illness

Secondary: after primary infection weakens the body defenses, secondary infections can be caused by opportunistic pathogens.

Subclinical: infections that don’t cause any noticeable illness

What is HAI

• Infections a person gets while receiving medical care.

• Over 70k deaths each year

• Also called nosocomial infections

• Most common in invasive procedures (sugery and catheters)

What is opportunistic pathogens?

Normally harmless microbiota that becomes harmful when the immune system is weakened or they enter a new part of the body.

What is epidemiology?

the science that studies when and where diseases occur and how they are transmitted in populations

What is case reporting?

Notifiable infectious diseases healthcare workers are required to report cases to US public health service to track potential outbreaks

What is Epidemic vs pandemic?

Epidemic: sudden spreading of a disease over a wide but isolated area

Pandemic: epidemic that spreads worldwide

What is endemic disease

A disease that is consistently present in a particular region

What is incidence

Number of new cases of an infection within a specified period

What is prevalence?

Percentage of total cases of infected individuals within a particular population

What is morbidity

The percentage of infected people who display symptoms

What is mortality

Percentage of infected people who die as a result of infection. Total deaths/total cases

What is case fatality ratio (CFR)

percentage of people with symptoms who die as a result of infection

what is R₀

basic reproductive number, the average number of people who will contract a disease from one infected individual

What is herd immunity

a point at which a disease has difficulty spreading through a population because a large enough percentage of the population is immune to it

What is zoonotic disease

A disease that has jumped from an animal to human

What is reservoir

the environment or host where a pathogen typically lives and multiplies; the primary source from which a pathogen initially spreads

What is a vector

a living organism that carries a disease causing agent from an infected host to a new host

What is vector borne disease

Disease that is transmitted via a vector

What are the 3 types of reservoirs?

• Human: primary living reservoir of human disease

• Animal: responsible for zoonoses

• Nonliving: most commonly soil and water

What are carriers

living reservoirs, do not exhibit signs or symptoms. Ex: typhoid Mary

What is transmission of disease and what are the 3 ways of transmission of disease

• How disease is transmitted between host.

1. contact

2. vehicle

3. vector

what is contact?

• Direct contact: person to person (cold and flu)

• Congenital: transmission from mother to fetus/newborn

• Indirect contact: through fomites

• Droplet: mucus droplets spread through coughing, sneezing, laughing, talking. Travels less than 1m

What is vehicle

• Airborne: droplets in dust that travel more than 1m

• Waterborne: spread by contaminated water

• Foodborne: food poisoning.

Cross-contamination: transfer of pathogens from one food to another

Fecal-oral transmission: can transfer microbes through waterborne, foodborne, or indirect contact transmission.

What is vector

• Mechanical: passive transport on body parts (flies and roaches)

• Biological transmission: pathogens are spread through bites.

What is pathogenicity

the ability of a microbe to cause a disease

What is virulence

the degree of pathogenicity; severity of disease

What are the 3 main portals entries of how microbes cause disease

• Mucous membranes:

Respiratory tract: easiest and most frequent route

Gastrointestinal tract: microbes must survive stomach acid, digestive enzymes, and bile in the small intestine.

Genitourinary tract: entry point for many STI, opportunistic infections may occur, especially if mucous membranes are damages (cuts)

• Skin: Broken skin provides portal of entry, hair follicles and sweat ducts also vulnerable.

• Parenteral: Enters directly into the body. Punctures, injections, bites, and surgery.

What is adherence and how to microbes attach?

• The ability of microogranisms to attach to host cell.

• attach by pili, fimbriae, glycocalyx, biofilms

How to viruses attach?

through spike proteins

What is adhesins

• molecules that allow microbes to bind to host cells.

• Can be spike proteins or surface proteins on bacteria(pili, fimbriae, or glycocalyx)

What is a ligand

• they bind to receptors on host cells

What do biofilms adhere to

• stick to surfaces and each other. Ex: adhere to teeth.

• Highly resistant to antibiotics, disinfectants, and immune system defenses

What is a capsule

a protective outer layer found on some bacteria that help them evade the immune system.

How to capsules help bacteria survive

• prevent phagocytosis so immune cells struggle to engulf and destroy microbes

• Can prevent phagocytic immune cell from attaching to bacterial cell

• Polysaccharide layer can mask surface antigens making it harder for the immune system to detect

how does mycolic acid help bacteria survive

• resists digestion after phagocytosis

• allows survival inside immune cells

Which bacterium uses mycolic acid to survive inside phagocytes

mycobacterium tuberculosis

What is the function of coagulase

• Clots blood, which can protect bacteria from phagocytosis and keep them isolated from other host defenses

what is the function of kinases

• They break down plasma proteins and dissolve blood clots

What does Hyaluronidase do to the host?

• It breaks down connective tissue, which can prevent the healing of infected wounds

What is the function of Collagenase?

• breaks down collagen, similar to Hyaluronidase and produced by similar bacteria

What is the function of proteases?

• Can destroy antibodies

What is antigenic variation?

• A mechanism where microbes change their surface proteins (antigens) so the host's immune system no longer recognizes them.

What are invasins?

Surface proteins produced by microbes that rearrange the host cell's cytoskeleton. allowing the microbe to enter the cell.

What are siderophores?

Proteins secreted by pathogens that bind iron more tightly than the host's own iron-binding proteins, allowing the microbe to steal it. This can lead to iron stores becoming depleted

What are toxins?

• substances that are produced by some microbes

What is toxigenicity

capacity to produce toxins

What is intoxication

signs/symptoms caused by toxins

What does the lipid A portion of LPS trigger?

• a massive immune response called cytokine storm that can cause damage to multiple organ systems

What is membrane-disrupting exotoxin?

• toxins that disrupt the plasma membranes

• kill host cells. Allow bacteria to escape phagocytosis

• examples: s. aureus and clostridium perfringens

What is hemolysins?

• disrupting toxins that destroy red blood cells by forming protein channels

What is superantigens exotoxin?

• toxins that provoke a very intense immune response

• Leads to release of huge amounts of cytokines

• example: staphylococcal toxin: cause food poisoning and toxic shock syndrome

What are pathogens?

disease-causing microbes

What is the immune system?

• composed of widely distributed proteins, cells, tissues, and organs

• Neutralize or destroy foreign substances

what is immunology?

• Study of immune responses and how they protect the host.

What is immunity?

• The ability to ward off disease caused by microbes or their products and to protect against environmental agents such as pollen, chemicals, and animal dander

What is susceptibility?

• refers to lack of immunity

Explain 1st,2nd, and 3rd line of defense

1st: keep pathogens on the outside or neutralize them before infection begins

2nd: slow or contain infections when first line defenses fail

3rd: target specific pathogens for destruction when second line defenses don’t contain infections

• 1st and 2nd line is for innate immunity and 3rd is for adaptive immunity.

What is innate immunity

• defenses present from birth

• non-specific (doesn’t recognize the invader)

• has no memory response (doesn’t remember past infections)

What is adaptive immunity?

• slower to respond than the innate

• Has memory

What are the physical and chemical barriers of the innate immune system?

• Physical: skin, organs, saliva, urine flow

• Chemical: stomach acid, ear wax, and lysozyme (enzyme found in tears and saliva)