Ethics - BSN NURSING

1. EXERCISE 12:
ORGANISM IN OUR
ENVIRONMENT

2. OBJECTIVES
• Demonstrate use of two important laboratory
tools.
• Study bacteria with which we are in daily contact.
• Sample the bacterial population in the laboratory.
• Grow bacteria from natural sources.
• Make student aware of and interested in the
microbial world around us.

3. MATERIALS
• Culture tubes of sterile nutrient broth
• Petri dishes containing sterile nutrient agar
• Bunsen burner
• Incubator
• Microscope
• Platinum wire loop
• Staining rack
• Microslides
• Gram stains
• Isotonic saline solution, sterile
• Glass – marking pencil
• Labels
• Lens paper
• Money for study: pesos
• Sterile cotton swabs

4. PROCEDURES
A. Sampling bacterial population in the laboratory
1. Bacteria in the air
a. Place on petri dish on top of the working place surface.
b. Remove lid from the label dish – do not invert lid.
c. Let dish remain exposed to the air for 15 mins.
d. Label the dish to indicate that the microorganisms
recovered on the surface of the nutrient agar came from the air.
e. Replace the cover of the dish, invert, and place in the
incubator for 24 hours.

5. 2. Bacteria on the tabletop
a.Do not cleanse or disinfect the surface of the worktable until this part
of the exercise is done.
b.Take a cotton swab moistened with sterile isotonic saline solution and
rub it briskly over the surface are of the worktable.
c. Lifting the lid of the petri dish are demonstrated by the instruction, run
the swab gently for one or two strokes over the surface of the nutrient
agar in the petri dish.
d.Lower the lid over the dish.
e.Label the petri dish to indicate that the microorganisms recovered
came from the top of the table.
f. Invert the dish and incubate for 24 hours.

6. 3. Bacteria on a doorknob or cabinet handle
a. Take a cotton swab moistened with sterile saline solution
and rub it briskly over the handles of drawers or cabinets in the
laboratory or over a doorknob.
b. Rub it gently over the surface of the nutrient agar in a petri
dish.
c. Cover the dish, invert, and incubate for 24 hours.
4. Bacteria in tap water faucet
a. Moisten a dry sterile cotton swab with water from cold
water tap.
b. Apply gently to the surface of the nutrient agar in a petri

7. 5. Bacteria on the floor
A. Take a sterile cotton swab moistened with sterile linen saline solution
and rub briskly over the floor.
B. Lift the lid of a petri dish and rub the swab gently over the surface of the
agar for one or two strokes.
C. Replace cover, label, and incubate for 24 hours.
6. Bacteria on walls
A. Take a sterile cotton swab moistened with sterile saline solution and rub
briskly over the walls.
B. Lift the lid of a petri dish and rub the swab gently over the surface of the
agar for or two strokes.
C. Replace cover, label, and incubate for 24 hours.

8. B. Study of colonial characteristics of bacteria
1. After the incubation period for the cultures taken in part A
of this exercise, examine the colonies formed on the surface of
the nutrient agar in the petri dish.
2. Observe the colonial morphology.
3. Make at least one bacterial smear from each petri dish and
stain by gram’s method.
4. Examine the smears microscopically with the oil immersion
lens of your microscope.
5. Observe microscopic characteristics of microorganisms
recovered.

9. A. Sampling bacterial population of our currency
1. Obtain working specimens from:
a.5-peso coin
b.20-peso bill
c.100-peso bill
d.500-peso bill
e.1000-peso bill
2. Dip tip of swab only into nutrient broth in culture tube to inoculate.
Label as to specimen.
3. Incubate at 37°c for 24 hours. Observe.
4. When growth appears, take out a loopful of broth to inoculate surface of
plate nutrient agar. Streak plate. Label plate.
5. Incubate plate at 37°c for 24 hours.
6. Observe growth. Count colonies, noting nature and different kinds.
7. Make gram stains of three different, yet representative colonies.

10. RESULTS FOR AIR (A) SAMPLE AFTER 24
HOURS INCUBATION PERIOD

11. RESULTS FOR TABLETOP (TT) SAMPLE AFTER
24 HOURS INCUBATION PERIOD

12. RESULTS FOR DOOR KNOB (DK) SAMPLE
AFTER 24 HOURS INCUBATION PERIOD

13. RESULTS FOR TAP WATER FAUCET (DK)
SAMPLE AFTER 24 HOURS INCUBATION
PERIOD
There are no notable
colonies. Therefore,
gram staining and
observation under the
microscope are not
performed.

14. RESULTS FOR FLOOR (F) SAMPLE AFTER 24
HOURS INCUBATION PERIOD

15. RESULTS FOR WALLS (W) SAMPLE AFTER 24
HOURS INCUBATION PERIOD

16. RESULTS FOR 5-PESO COIN (5) SAMPLE AFTER
24 HOURS INCUBATION PERIOD

17. RESULTS FOR 20-PESO BILL (20) SAMPLE
AFTER 24 HOURS INCUBATION PERIOD

18. RESULTS FOR 100-PESO BILL (100) SAMPLE
AFTER 24 HOURS INCUBATION PERIOD

19. RESULTS FOR 500-PESO BILL (500) SAMPLE
AFTER 24 HOURS INCUBATION PERIOD

20. RESULTS FOR 1000-PESO BILL (1000) SAMPLE
AFTER 24 HOURS INCUBATION PERIOD