Final Exam

What is epidemiology?

Science that deals with when and where diseases occur and how they are transmitted in the human population

What is communicable versus noncommunicable disease?

Communicable diseases are infectious and spread person to person, whereas noncommunicable diseases are chronic and do not transmit

What are fomites?

A non-living object that help spread infections

What are endemic diseases and an example?

A disease that is always present in a population within a georgraphic area; common cold

What is an epidemic disease and an example?

Many people in a given area acquire a disease in a short period of time; COVID-19, HIV

What is a pandemic disease and example?

Spread over the population of many continents; HIV and COVID-19

What is index case?

First case of a disease

What is direct transmission?

Spread between host via direct contact or droplet spread

What is mechanism transmission?

Indirect transmission on the surface of a mechanical vector, like an insect

What is biological transmission?

Indirect transmission via the saliva of a biological vector

What is a host?

An organism that harbors the pathogen

What is a pathogen?

A disease-causing microorganism which needs to come in contact with the host to cause disease

What is a reservoir?

Continual source of infection or disease that can be human, animal, or non-living

What is a carrier?

A person that harbors a disease but is not displaying any sign of disease

What is the formula to calculate infection rate?

number of infected individuals/ population at risk

What is the optimal growth range of psychrophilic bacteria?

15 degree C or below

What is the optimal growth range of psychrotrophic bacteria?

20-30 degree C

What is the optimal growth range of mesophilic bacteria?

25-40 degree C

What is the optimal growth range of thermophilic bacteria?

45-65 degree C

What is the optimal growth range of hyperthermophilic bacteria?

80 degree C or above

What are examples of dry heat?

Hot oven, bunsen burner flame

What are examples of moist heat?

Boiling, pasteurization, autoclaving

What temperature and time are needed for pasteurization?

63 C for 30 minutes or 72 C for 15 sec

What is the temp and time for boiling?

100 C for 10 min

What is the radiant energy spectrum from largest wavelength to smallest?

Radiowaves, Microwaves, Infrared radiation, Visible Light, Ultraviolet, X-Rays, and Gamma Rays

What damage can UV light induce and what fixes it?

Thymine dimer; photolyases

What are the types of UV Light?

UVA, UVB (synthesize Vitamin D), UVC

What are disinfectants?

Chemicals that lower the level of microbes on the surface of inanimate objects.

What are antiseptics?

They decrease the number of microbes on living tissue

What three strains of bacteria are used to do American Official Analytical Chemist Use-Dilution Test?

Samonella enterica, Staphylococcus aureus, and Pseudomonas aeruginosa

What are the characteristics of the genus Pseudomonas?

Gram-negative bacillus with one or more flagella, very diverse, but similarities are non-spore forming, non-coliform, catalase positive, and oxidase variable

What are the characteristics of Pseudomonas aeruginosa?

Oxidase-positive species with one flagellum. Typically create green colonies due to secondary metabolites, increasingly antibiotic resistant, and opportunistic pathogen

What is antibiosis?

Process of one organism inhibiting another

What are two methods of how antibiotics work?

Inhibition of cell wall formation (peptidoglycan) and inhibition of DNA synthesis, which prevents propagation so immune system can fight

What method tests the effectiveness of antibiotics against certain bacteria?

Disk-Diffusion Method

What determines if a bacterium is antibiotic resistant?

If the zone of inhibition reaches a certain diameter

What type of media is a Mueller Hinton?

Enrichment

What is a special feature of Mueller Hinton plate?

It contains starch, which inhibits exotoxins produced by bacteria from interfering with antibiotic disk and allows for easy diffusion of antibiotics

What plate is used to do disk-diffusion method?

Mueller-Hinton Plate

What is minimal inhibitory concentration?

The lowest concentration of an antimicrobial agent that inhibits the visible growth of a microorganism

What bacterium is known to be mutualistic on the skin?

Propionibacterium

What type of bacterium is typically a parasitic?

Transient bacterium

What do normal skin microbiota need to be tolerant to?

Salt and dryness

What areas are more bacteria found in on the skin?

Moist areas

What are characteristics of Staphylococcus genus?

Gram positive, catalase producing, and facultative anaerobes

What are the characteristics of Staphylococcus aureus?

Gram-positive microbes on skin and respiratory tract that can be pathogenic. Positive for catalase and nitrate reduction

What do pathogenic Staphylococcus aureus produce?

Coagulase, which activates prothrombin into staphylothrombin, which activates fibrinogen to fibrin.

What plate mimics environment created by the skin?

MSA

What does MSA allow us to do?

Differentiate pathogenic and non-pathogenic species

What type of enzyme breaks down mannitol in MSA plate?

Exoenzyme

What genera are commonly found in the throat?

Staphylococcus, Streptococcus, Neisseria, and Haemophilus (antagonism)

What can you use to tell the if streptococcus is pathogen?

Hemolytic reactions

What media is used to determine the pathogenicity of Streptococcus?

Sheep Blood Agar

What type of media is Sheep Blood Agar?

Enrichment and differential for hemolytic capability

What are the three types of hemolytic reactions?

Alpha-hydrolysis, Beta-hydrolysis, Gamma-hydrolysis

What does an alpha-hydrolysis result look like and mean?

Green, cloudy around the colony due to partial destruction of RBCs caused by hydrogen peroxide produced by bacteria; typically non-pathogenic but can be pathogenic

What does a beta-hemolysis result look like and mean?

Clear around the colony due to the complete destruction of RBCs; pathogenic

What does a gamma-hydrolysis result look like and mean?

No visible change because the blood cells are intact; non-pathogenic

What is the purpose of blood agar?

Enrichment medium because of blood and its growth factors present, and differential for types of hemolysis

What are the mechanisms of blood agar?

Patterns of hemolysis are used to identify pathogenicity of Streptococci, and detects presence of exoenzyme hemolysin

How is blood agar incubated?

In a candle jar to create microaerophillic environment

What agar is used to select for yeast and molds?

Sabouraud Dextrose

What type of media is Sabouraud Dextrose Agar?

Selective for mold, yeast, and some filamentous bacteria

What is urine?

Liquid waste product produced by the kidneys, collected in the bladder, and excreted through the urethra

What is urine mainly composed of?

Water

What does transparent/pale yellow urine mean?

Normal

What does clear, dark yellow, dark orange/brown, pink urine mean?

Overhydrated, dehydrated, jaundice, too many beets

What does green, blue, or black urine mean?

Asparagus, methylene blue, melanuria

What is the upper urinary tract composed of?

Kidney, ureters, and bladder

What bacteria are in upper urinary tract?

Normal microbiota that tends to be gram positive

What is the lower urinary tract composed of?

Urethra

What bacteria is found in urethra?

Mostly gram positive, including Streptococcus, Bacteriiodes, Mycobacterium, and Neisseria

What do large amount of bacteria in urine indicate?

Contamination

What type of pathogen are UTI typically caused by?

Opportunistic pathogens

Why are women more likely to get UTI than mean?

Women have shorter urethra and it is closer to the anus

What indicates a UTI?

More than 100,000 bacteria from the same species and more than 100 coliforms

How can UTIs be prevented?

Hydration, cranberries, vitamin C, probiotics

Why should you close the toilet lid when you flush?

Flushing produced bioaerosols, which can contaminate other objects

What are characteristics of MacConkey agar plate?

Selective for gram negative and differential for lactose fermentation

What indicator does MacConkey Agar use?

Neutral red, meaning if lactose is fermented, acid is released and pH goes down and plate turns pink

How does MacConkey inhibit Gram-positive growth?

It contains bile salts and crystal violet

How do you read a MonConkey plate?

Growth means Gram-negative bacteria, especially enterics. No growth means gram positive. Pink means lactose fermenting, and no color change (yelllow) means non-lactose fermenting

How do you calculate CFU for Mac plate?

Same formula, but DF is 0.01 since 1 loop is 10 microliters

What type of bacteria are found in the large intestine?

Anaerobes and facultative anaerobes

What are most gastrointestinal diseases caused by?

Ingestion of contaminated food or water

What are the characteristics of Tomato Juice Agar?

Enrichment media and selective for Lactobacillus

What bacteria are rich in probiotics?

Lactobacillus

What are Tomato Juice Agar is incubated?

CO2 jar that creates an anaerobic environment

What is TSI Slant composed of?

Phenol red, lactose, sucrose, glucose, sodium thiosulfate, and ferrous sulfate

What four biochemical tests are in the TSI Slant?

1. Carbohydrate fermentation

2. Oxygen requirement

3. Hydrogen sulfide production

4. Thiosulfate as final electron acceptor (strictly anaerobic)

What indicator do TSI slants use?

Phenol red

What does red top and bottom yellow mean for Carbohydrate fermentation on TSI slant?

Glucose fermentation

What does all yellow slant mean for TSI slant?

Glucose, lactose, and/or sucrose fermentation

How do you read the results for thiosulfate as a final electron acceptor?

No gap under the agar means thiosulfate was not used as an electron acceptor and did not produce hydrogen gas, and a gap means it was

What is the difference between probiotics and prebiotics?

Probiotics are supplements with live bacteria that improve the gut microbiome, whereas prebiotics are foods high in fiber with no live microorganisms

What benefit does the appendix have?

It serves as a safehouse for good bacteria that can repair gut microbiome after being damaged.

What bacteria is most commonly found in probiotics?

Lactobacillus

What are characteristics of Type A blood?

RBCs have A antigen, and serum has anti-B antibodies

What are the characteristics of Type B blood?

RBCs have B antigen, and serum has anti-A antibodies

What are the characteristics of Type AB blood?

RBCs have A and B antigens, and serum has no antibodies