PPT

1. MC3 – Microbiology &
Parasitology
JESSIE T. ORANO, RN, RM, MN, MAN, MMHA
DR. ARIES M. BALDONADO, RN, RM, LPT
Instructors
https://www.youtube.com/watch?v=URUJD5NEXC8

2. WEEK 3 – PART I
MICROBIAL GROWTH
Learning Outcome:
1. Apply the principles of microbial growth in
understanding development of diseases.

3. Microbial Growth
 Increase in number of cells,
not cell size.
 One cell becomes colony of
millions of cells.
MICROBIAL GROWTH
• Control of growth is
important for infection
control and growth of
industrial and biotech
organisms.

4. Factors regulating Microbial
Growth
• Nutrients
• Environmental conditions:
temperature, pH, osmotic
pressure
• Generation time
MICROBIAL GROWTH
CHEMICAL REQUIREMENTS
WATER!!!
ELEMENTS: CHONPS
TRACE ELEMENTS: Iron, Zinc,
Chromium, Selenium,
Fluorine, Iodine
ORGANIC: Glucose, Vitamins,
amino Acids

5. NUTRITIONAL CATEGORIES
SAPROBE – lives on organic
matter of dead organisms.
PARASITE – lives on organic
matter of living host =
pathogens.
MICROBIAL GROWTH
ENVIRONMENTAL FACTORS
Temperature
O2
pH
Osmotic Pressure
Others: radiation, atmospheric
pressure

6. TEMPERATURE OPTIMA
CATEGORIES
Psychrophiles: cold-loving
Mesophiles: moderate
temperature-loving
Thermophiles: heat-loving
Each has a minimum, optimum,
and maximum growth
temperature.
MICROBIAL GROWTH
OXYGEN REQUIREMENTS
 Obligate aerobes – require
O2.
 Facultative anaerobes – can
use O2 but also grow without
it.
 Obligate anaerobes – die in
the presence of O2.

7. pH CHARACTERISTICS
 Most bacteria grow
between pH 6.5 and 7.5
 Acid (below pH 4) good
preservative for pickles,
sauerkraut, cheeses
 Acidophiles can live at low
pH
MICROBIAL GROWTH
pH CHARACTERISTICS
 Many bacteria and viruses
survive low pH of stomach to
infect intestines.
 Helicobacter pylori lives in
stomach under mucus layer.

8. BINARY FISSION
 The process that bacteria
use to carry out cell division.
 Asexual reproduction by a
separation of the body into
TWO new bodies.
BACTERIAL DIVISION
BINARY FISSION
 The organism duplicates its
genetic material or the DNA
and the divides into two
parts (CYTOKINESIS), with
each new organism
receiving same copy of DNA.

10. OTHER ALTERNATIVES
BUDDING:
 In this process a small bud-
forms at one end of the
mother cell.
BACTERIAL DIVISION
OTHER ALTERNATIVES
 As growth proceeds, the size
of the mother cell remains
about constant, but
the bud enlarges. When
the bud is about the same
size as the mother cell, it
separates.

11. OTHER ALTERNATIVES
CONIDIOSPORES:
 Asexual reproduction among
fungi.
BACTERIAL DIVISION
OTHER ALTERNATIVES
FRAGMENTATION
 also known as splitting, is a
form of asexual
reproduction in which an
organism splits into
fragments.
 Each fragment develops into
a mature clone genetically
and morphologically identical
to its parent.

12. BACTERIAL DIVISION
PROCESSES BY WHICH MICROORGANISMS
GROW AND MULTIPLY
OTHER ALTERNATIVES
FRAGMENTATION

13. BACTERIAL DIVISION
PHASES OF GROWTH
 LAG PHASE – making new
enzymes in response to new
medium.
 LOG PHASE – exponential
growth.
 Desired for production of
products.
 Most sensitive to drugs
and radiation during this
period.
GENERATION TIME
 Time required for cell to
divide/for population to
double.
 Average for bacteria is 1-3
hours.
• E. coli generation time = 20
min. 20 generations (7
hours), 1 cell becomes 1
million cells!

14. PHASES OF GROWTH
PHASES OF GROWTH
 STATIONARY PHASE –
nutrients becoming limiting
or waste products becoming
toxic.
death rate = division rate
 DEATH PHASE – death
exceeds division.

15. PHASES OF GROWTH
PHASES OF GROWTH
 DIRECT METHODS – count
individual cells.
 INDIRECT METHODS –
Measure effects of bacterial
growth.

16. WEEK 3 – PART II
CONTROL OF MICROBIAL GROWTH
Learning Outcome:
1. Utilize techniques that effectively control
microbial growth.

17. CONTROL OF MICROBIAL
GROWTH
 Microorganisms are
controlled by means of
physical agents and
chemical agents. Physical
agents include such
methods of control as high
or low temperature,
desiccation, osmotic
pressure, radiation, and
filtration.
 Control of microorganisms is
essential in order to prevent
the transmission of diseases
and infection, stop
decomposition and spoilage,
and prevent unwanted
microbial contamination

18.  Control by chemical
agents refers to the use of
disinfectants, antiseptics,
antibiotics, and
chemotherapeutic
antimicrobial chemicals.
 PHYSICAL AGENTS
 TEMPERATURE
 Temperatures below the
minimum usually have
a static action on
microorganisms. They
inhibit microbial growth by
slowing down metabolism
but do not necessarily kill
the organism.
CONTROL OF MICROBIAL
GROWTH

19.  PHYSICAL AGENTS
 TEMPERATURE
 Temperatures above the
maximum usually have
a cidal action, since they
denature microbial enzymes
and other proteins.
 Moist Heat: Autoclaving,
Boiling Water
 Dry Heat: Hot air
Sterilization, Incineration
 Pasteurization – mild
heating of milk to kill
spoilage microorganisms or
pathogens.
CONTROL OF MICROBIAL
GROWTH

20.  PHYSICAL AGENTS
 DESICCATION
 Also known as drying, generally
has a static effect on
microorganisms. Lack of water
inhibits the action of microbial
enzymes. Dehydrated and
freeze-dried foods, for example,
do not require refrigeration
because the absence of water
inhibits microbial growth.
 PHYSICAL AGENTS
 OSMOTIC PRESSURE
 Movement of water
through semipermeable
membrane from an area
of lower solute (greater
water) to greater solute
(lower water)
concentration.
CONTROL OF MICROBIAL
GROWTH

21.  PHYSICAL AGENTS
 RADIATION
 Ultraviolet and Ionizing Radiation
are frequently used to reduce the
microbial populations in hospital
operating rooms and sinks,
aseptic filling rooms of
pharmaceutical companies, in
microbiological hoods, and in the
processing equipment used by
the food and dairy industries.
 PHYSICAL AGENTS
 OSMOTIC PRESSURE
 Water flows thru these
processes: Hypotonic
(water flow into cell);
Isotonic (equal) and
Hypertonic (water flows
out of cell).
CONTROL OF MICROBIAL
GROWTH

22.  PHYSICAL AGENTS
 RADIATION
 Only microorganisms on
the surface of a material that are
exposed directly to the radiation
are susceptible to destruction
and bacterial endospores are
more resistant to ultraviolet
radiation. UV radiation can also
damage the eyes, cause burns,
and cause mutation in cells of
the skin.
 PHYSICAL AGENTS
 FILTRATION
 Microbiological membrane filters
provide a useful way of sterilizing
materials such as vaccines,
antibiotic solutions, animal sera,
enzyme solutions, vitamin
solutions, and other solutions
that may be damaged or
denatured by high temperatures
or chemical agents.
CONTROL OF MICROBIAL
GROWTH

23.  CHEMICAL AGENTS
 DISINFECTANTS, ANTISEPTICS,
AND SANITIZERS
 Disinfection is the elimination of
microorganisms, but not
necessarily endospores, from
inanimate objects or surfaces,
whereas decontamination is the
treatment of an object or
inanimate surface to make it safe
to handle.
 PHYSICAL AGENTS
 FILTRATION
 The filters contain pores small
enough to prevent the passage of
microbes but large enough to
allow the organism-free fluid to
pass through.
CONTROL OF MICROBIAL
GROWTH

24. CHEMICAL AGENTS
c. The term sanitizer describes
an agent that reduces, but may
not eliminate, microbial
numbers to a safe level.
CHEMICAL AGENTS
a. The term disinfectant is used for
an agent used to disinfect
inanimate objects or surfaces but
is generally to toxic to use on
human tissues.
b. The term antiseptic refers to an
agent that kills or inhibits growth
of microbes but is safe to use on
human tissue.
CONTROL OF MICROBIAL
GROWTH

25. CHEMICAL AGENTS
3. The kinds of
microorganisms present. Endosp
ore producers such
as Bacillus species, Clostridium sp
ecies, and acid-fast bacteria
like Mycobacterium
tuberculosis are harder to
eliminate.
CHEMICAL AGENTS
 Factors influencing antimicrobial
action of disinfectants and
antiseptics:
1. The concentration of the
chemical agent.
2. The temperature at which the
agent is being used. Generally,
the lower the temperature, the
longer it takes to disinfect or
decontaminate.
CONTROL OF MICROBIAL
GROWTH

26. CHEMICAL AGENTS
 Modes of Actions of
Disinfectants, Antiseptics and
Sanitizers:
 Damage the lipids and/or
proteins of the semipermeable
cytoplasmic membrane of
microorganisms resulting
in leakage of cellular
materials needed to sustain life.
CHEMICAL AGENTS
4. The number of
microorganisms present. The
more microorganisms present,
the harder it is to disinfect or
decontaminate.
5. The nature of the material
bearing the microorganisms.
Organic material such as dirt and
excreta interferes with some
agents.
CONTROL OF MICROBIAL
GROWTH

27.  Examples of Chemical agents
commonly used:
 Phenols and Phenolics – kills
bacteria by denaturing the
protein cell membrane.
 Soaps and Detergents – mildly
antimicrobial; aids in
mechanical removal of
microorganisms.
 Alcohol – 70% kills bacteria;
once evaporated, cidal effect
ceases.
CHEMICAL AGENTS
 They may denature microbial
enzymes and other
proteins, usually by disrupting the
hydrogen and disulfide bonds that
give the protein its three-
dimensional functional shape.
This blocks metabolism.
CONTROL OF MICROBIAL
GROWTH

28.  Examples of Chemical agents
commonly used:
 Iodine and Iodophores –
denature proteins.
 Aldehydes - such as
formaldehyde (formalin) and
glutaraldehyde, denature
microbial proteins.
 Peroxygens - kills
microorganisms by oxidation and
subsequent disruption of their
cytoplasmic membrane.
 Examples of Chemical agents
commonly used:
 Acids and Alkalis - alter
membrane permeability and
denature proteins and other
molecules.
 Heavy Metals - such as mercury,
silver, and copper, denature
proteins.
 Chlorine - reacts with water to
form hypochlorite ions, which in
turn denature microbial
enzymes.
CONTROL OF MICROBIAL
GROWTH

29.  Summary:
 Microbial growth refers
to an increase in number of
cells rather than an
increase in cell size.
 Bacteria divide and
reproduce asexually.
 The control of microbial
growth may
involve sterilization,
disinfection, antisepsis,
sanitization.
 Examples of Chemical
agents commonly used:
 Ethylene Oxide Gas – used
for sterilization (6-12 hrs.
exposure).
CONTROL OF MICROBIAL
GROWTH

30. END
TAKEOUT ACITIVITY
HANDWASHING
Identify the 5 moments of
Handwashing
Differentiate Medical
Handwashing from Surgical
Handscrubbing
CONTROL OF MICROBIAL
GROWTH