microbiology - final lecture (exam practice)

Antiseptic

chemical that can be applied on skin/mucous membranes (ex: alcohol)

Antibiotic

antimicrobial substance (medicine) that can fight against bacterial infections (prokaryotes)

Disinfectant

chemical that can kill microbes on surface; has toxicity (ex: bleach)

Sanitation

refers to cleanliness of public health settings

Sterlizations

removal (or killing) of ALL microbes

Decontamination

removal of UNWANTED microbes

Laboratory and hospital floors are never made of wood, or carpeting. Why?

wood: microbes can easily enter/absorb the flooring (porous)

carpeting: microbes can easily get stuck (hard to clean) within the fibers of the flooring + has more surface area

What is filtration? How does it work?

it's a sterilization method by eliminating bacteria by separating microorganisms from sterilized medium by physical barriers

- does not work for viruses

- big filters for yeasts

- small filters for bacteria

What is an autoclave? How does it work?

a machine to put steam under pressure to kill microbes

- above 121* C

What is pasteurization? Where is it used? What does it do?

heating/cooling temperatures rapidly only on liquids to kill pathogenic organisms (not everything)

What are the common targets of antibiotics? How does this make antibiotics be harmful bacteria & not the host?

bacteria

- it's harmful towards bacteria & not the host because bacteria has certain structures/processes unique to bacteria & not found in human cells

What is a wide spectrum antibiotic?

an antibiotic that affects many microbes & normal flora

What is a narrow spectrum antibiotic?

an antibiotic that affects a small group of microbes, & you need identification

- less harmful towards normal flora

Vancomycin mostly targets G+ organisms. Is this broad spectrum or narrow spectrum?

narrow-spectrum because it targets specifically G+ organisms rather than a wider spectrum

Would you use the above antibiotic against E.coli? Staphylococcus?

against staphylococcus as vancomycin targets G+ & E.coli is a G- bacteria, whereas Staphylococcus is a G+ bacteria

What are some common mechanisms of resistance in bacteria?

change in target: the bacteria changes & therefore ribosomes are different & antibiotics can no longer stick

antibiotic pumps: bacteria have pumps to take antibiotics out

antibiotic cleaving enzymes: antibiotic gets into the cell but gets chopped out

How does resistance arise?

by overuse or improper use of antibiotics

- by only killing part of population sensitive antibiotic, which leaves less for immune system to detect & remain there

What can we do to limit antibiotic resistance?

finish antibiotics

What is innate immunity?

always active, non-specific, first defense

first line of defense

mechanical/physical barriers such as:

- skin, stomach, intestinal tract, eyes, urethra

second line of defense

encounters inside the body, cells/compounds target invading organisms:

- respiratory tract, plasma, leukocytes

third line of defense

acquired immunity

- leukocytes

What are antibodies?

immunoglobins that work against antigens

What is immunization? What are the different types of vaccines?

make resistance against a pathogen by stimulating the body's immune response against disease

- responds to the antigen as if it's an actual germ

- body makes antibodies & remember it

What are the differences between primary and secondary immune response?

primary immune response: produced by initial exposure to pathogen (slow response + production of memory cells)

secondary immune response: quickly recognize & combat pathogen upon subsequent exposures (faster + robust due to memory cells)

The current small pox vaccine is the active "live" vaccinia virus. What are some potential problems with this?

cause adverse affects in immunocompromised individuals + unintended transmission

What are immunoassays?

laboratory techniques (tests) to detect & quantify specific presence/concentration antigens or antibodies in a sample

How does ELISA work?

1. take antigen —> into animals = produces anti-BLANK antibodies

2. separate serum

3. attach antigen to surface

4. add enzyme-linked antibody to target

5. add substrate

What are nosocomial infections? Name three agents of these infections.

infections commonly obtained in hospital settings

- pneumonia

- MRSA

- UTIs

- pseudomonas aeruginosa

- clostridium difficle

What are some common features of nosocomial infections?

occurrence in hospital-settings

- potential for antibiotic resistance

- invasive procedures

What are the two most common types of infections?

- UTIs: urinary tract infections (usually by E.coli)

- respiratory infections

Yersinia pestis is the causative agent of the plague. Describe the infection.

it's a zoonotic bacteria found in small mammals/fleas

- bubonic/pneumonic

What is botulism. How would you go about avoiding botulism?

an illness caused by Clostridium botulism

- properly can/preserve food; avoid consuming gas-producing goods

Oral fecal pathogens are commonly spread how? Make sure to consider both developed & developing countries.

contamination of food/water with feces

- developed countries: point-source outbreaks

- developing countries: sewage gets into water

S. aureus is an opportunist, whereas S. epidermidis is usually non-pathogenic. Why (think virulence factors)?

S. epidermidis lacks the amount of virulence factors S. aureus has such as toxins, enzymes, & surface proteins.

Why did I italicize the two organism names above?

to indicate their Latinized names/scientific notations

What are some precautions that would help with nosocomial infections?

hand hygiene, PPE, aseptic technique, environmental cleaning, isolation

Can nosocomial infections be eliminated? Why?

no as the healthcare-setting is high risk for consistent infections from incoming patients, procedures, & pathogens

What are the factors that affect getting an infection?

virulence factors, population density, social behavior, healthcare/infrastructure, immunity levels, travel/migration

What are the steps in an infection? How does virulence factors affect these?

1) exposure

2) adhesion/attachment

3) invasion

4) colonization

virulence factors: enhances pathogenic obtainment

What are naked and enveloped viruses? Which is more resistant to destruction?

- naked viruses: capsid, genetic material, spikes, NO envelope

- enveloped viruses: capsid, genetic material, spikes, envelope

naked viruses are more resistant to destruction

What are the steps in viral replication?

1) virus enters host cell

2) virus replicates inside host cell

3) host cell dies & virus spills out

Why can't we use antibiotics to control a viral infection?

antibiotics are specifically medicines for bacteria & not viruses

Typically how are viral infections spread?

respiratory droplets, oral/fecal, sexually transmitted, casual contact, normal flora, fomites, vectors, zoonoses, environment, parenteral, nosocomial

Know the structure of a virus.

capsid, genetic material (DNA/RNA), spikes (attachment to host)

How are viruses classified?

capsid shape, envelope presence, nucleic type, host range, disease caused

How does skin protect us against infections?

part of the innate immune system & the first line of defense which serves as the mechanical/physical barrier

- covered by dead cells that are constantly shed

- secretes toxic substances (sweat, sebum)

What is antibiotic resistance? How does it arise? What mechanisms are behind this phenomenon?

bacteria evolves to not be susceptible to drugs

- arises by misuse/overuse of drugs

Why don't we get more UTIs?

hygiene practices IDK

Which demographic group is prone to UTIs?

females due to shorter urethras & less frequent urination

Why are there more respiratory illnesses in winter?

reduced ventilation due to being inside, dry air (dries out mucous membranes)

How does a home pregnancy test or home COVID tests work?