Experience 1
Parts of Microscope:
Ocular- lens you look through (10x)
Objective- lens above stage (4x, 10x, 40x,100x (oil))
Stage- slide of sample is placed
Focusing knob- located on sides, coarse- low dry, fine- high dry/oil
Condenser-focusing light
Diaphragm- limits amount of light (pupil)
Magnification calculation: Ocular x Objective
Experience 2
Simple stain- single dye that colors everything, used for size/shape of bacteria
Procedure: Flood slide with dye: take several drops of dye (crystal violet, safranin or methylene
blue) and cover the entire area of the smear with the dye. Let it sit for approximately 1 minute.
Rinse with water until the draining water is mostly clear. Blot the slide dry.
Differential stain- 2 or more dyes, used to differentiate bacterium species
Gram stain- most common differential stain
Procedure: 1. Crystal violet (primary stain), 2. Grams iodine (mordant), 3. Alcohol (decolorizer),
4. Safrain (counter stain)
Acid fast stain- used against bacterium with thick waxy coat that gram stain cant identify
Acid fast cells- stain pink Mycobacterium, Non-acid fast cells- stain blue S. pyogenes
Procedure: 1. Smear 2. Air dry/heat fix, 3. Place slide on aluminum foil on hot plate, 4. Cover
smear with carbol-fuchsin, 5. Remove slide, 6. Rinse with acid-alcohol, 7.counterstain with
EMB
Experience 3
Culture media: Liquid- broth, Semisolid- gelatin, Solid- agar
Semisolid & Solid- Solid has more agar than semisolid. Semisolid-petri plates/test tubes,
Solid-test tubes (slants)
Complex media- contains unknown # of nutrients in media
Synthetic media- contains known # of nutrients in media
Inoculation- applying/adding bacteria to medium
Incubation- process of allowing growth of bacteria
Calculating OCD: CFU/ ml, # of colonies counted (CFU) / volume of inoculating loop (ml)
Selective: allows only 1 type of bacteria to grow
Differential: allows growth of many bacterium
Pour Plate Method-Liquid suspension of bacteria added to liquid auger mixed carefully and the
entire suspension is then poured into sterile Petri plate
Spread Plate Method small amount of liquid suspension of bacteria placed on surface of Agra
plate and then carefully spread over surface
these two methods are most useful for isolation of pure colonies and for determining # of
bacteria present
Streak Plate Method can be used with either liquid or solid & is the quickest and easiest
method of obtaining a pure culture
Urine Streak semi quantitative method of determining an approximate number of
bacterial cells in fluids such as urine
Experience 4
Enterobacteriaceae: anaerobic, gram – ferment glucose and are oxidase Eosin Methylene Blue (EMB) Agar: Selective medium for gram negative bacteria as well as
differential medium for lactose fermentation
SIM’s media: Semisolid medium that can be used to test for production of indole the reduction of
sulfur and motility
+ result: black precipitate
Indole test:
+ result: cherry red ring on the top of the medium
- result: no color change
MR-VP:
+ result:
MR red color
VP red-band an upper part of solution
- result:
MR no color change
VP copper colored band
Citrate utilization test
+ result: BLUE
- result: GREEN
Carbohydrate fermentation test production of gas see if substance can use fermentation of
carbs
+ result: YELLOW
- result: RED
Enterotube
Glucose
+ result: YELLOW (wax lifted)
- result: RED
LYS
+ result: PURPLE
- result: YELLOW
ORNI
+ result: PURPLE
- result: YELLOW
H2S
+ result: BLACK
- result: BEIGE
INDOLE
+ result: RED
- result: BEIGE /NO COLOR
ADONITOL
+ result: YELLOW
- result: RED
LACTOSE
+ result: YELLOW
- result: RED
ARABINOSE
+ result: YELLOW
- result: RED
SORBITOL
+ result: YELLOW
- result: RED
VP
+ result: RED
- result: NO COLOR
DULCITOL
+ result: YELLOW
- result: GREEN
PA
+ result: BLACK/GREY
- result: GREEN
UREA
+ result: PINK
- result: BEIGE
CITRATE
+ result: BLUE
- result: GREEN
Experience 5
Gram + bacteria include: Staphylococci & Streptococci
S. aureus- Scalded skin syndrome skin infections boils toxic shock syndrome food poisoning
septic arthritis pneumonia endocarditis
S. epidermitis- artificial valve endocarditis catheter an shunt infections prosthetic infection
S. saprophyticus- UTI
S. pyogenes- pharyngitis, scarlet fever, Toxic shock syndrome skin infections
S. agalactiae- pneumonia, meningitis
Group D Streptococci Enterococcus- UTI
S. pneumoniae- pneumonia, meningitis, sinusitis
S. Viridans- dental carries S. mutans
Catalase
+ result: Staphylococcus species clusters
- result: Streptococcus species chains
Mannitol salt agar+ result: YELLOW = S. aureus
- result: PINK= S. Epidermitis
Hemolysis of Blood agar
Alpha- partial clearing
Beta- complete or total clearing
Gamma-no clearing
CAMP test
+ result: Large arrowhead shaped hemolytic zone
NACL BROTH
+ result: bubbles, cloudiness
Bile Esculin
+ result: slant medium turns black
Sensitive: large clear zone
Resistant: no clear zone
Intermediate: small clear zone
Experience 8
Importance of Fungi: Antibiotics, Food production, Substance production, Food spoilage,
Allergies
Fungi- eukaryotes
Body of fungus- Mycelium
Individual strands- hyphae
Hyphae have cell walls made of chitlin
Fungi reproduce sexually/asexually
Asexual- produce large spores, outer covering of spore is called Sporangia, if it is at the end of
specialized cells it’s called Conidiophores
Asexual spores called- Conidia
Experience 10
Epidemiology is the study of the frequency and distribution of disease (pathogens). It
allows for development of guidelines for the prevention and control of certain diseases.
Some of the videos posted for Experience #10 will show how some infectious diseases
are potential epidemics just based on their high infection and transmission rates. Skilled
healthcare officials and experienced epidemiologists’ study and plan how to prevent
infectious diseases from becoming epidemics.
Public Health Microbiology refers to a cross-cutting area that spans the fields of human,
animal, food, water, and environmental microbiology, with a focus on human health and
disease. Public Health Microbiology Laboratories play a central role in detection,
monitoring, outbreak response, and providing scientific evidence to prevent and control
infectious diseases. PHM requires laboratory scientists with ability to work effectively
across disciplines, particularly with epidemiologists and clinicians.
Diseases are spread 8 different ways and the associated diseases with each mode of
transmission.
1. Airborne- inhalation of respiratory droplets or particles containing a pathogen
Diseases: Measles, Valley fever, COVID-19, Influenza, Anthrax
2. Blood- direct contact with infected blood, blood transfusion, sharing needles
Diseases: HIV, Hepatitis, Ebola, Sepsis
3. Direct skin- skin to skin contact with infected individual
Diseases: MRSA, Herpes, Athletes foot, Superficial/Cutaneous Mycosis
4. Vectors (insects)- mosquitos
Diseases: Malaria, Yellow fever, Lyme disease, Plague, Zika, Encephalitis, West
Nile virus
5. Food- eating contaminated food
Diseases: Giardiasis, Salmonellosis
6. Water- drinking contaminated water
Diseases: Cholera, Giardiasis, Amoebiasis
7. Sex- sexual intercourse through discharges/fluids
Diseases: HIV, Chlamydia
8. Animals (Zoonotic)- animals to humans through air (influenza) or bites/saliva (rabies)
Diseases: Avian Flu, Ebola, Rabies, Influenza