Download Question bank- 4.Growth and reproduction In the culture media the

Question bank- 4.Growth and reproduction
a. In the culture media the bacterial growth is low ,explain pain?
due to:
1. Less of nutrient substances.
2. Accumulation of waste products.
b. Mode of reproduction or duplication.
c. Growth culture steps and their creteria
1.
Lag phases:
Bactria attached itself to the habitat in this phase we see
a. No multiplication
b. Increasing in size without cell division.
c. Time of this phase (duration) is varying from a few hours to some days this variety
depends on nature of organism ex, E.coli 1-4 hours , T.b 3-7 day .
2. Logarithmic phase or exponential phase or phase of increasing
1. In this phase gets division of maximum logarithmic geometric curve ……there is
increasing in the number of bacteria cells.
2. The duration is varying in different bacteria; it's about 6-8 hours.
3. Stationary phase
It means the constant number of bacteria cell in this phase
1. The bacterium is decrease to multiply at maximum rate.
2. Death rate begins
The bacterial cells which produce from the division is equal to death cells in this phase
4. Decline phase
Phase of decreasing, in this phase
1.
No division or the division is slowly rate
2. Increase in the death rate
So there are no bacteria no living bacteria in a few days.
How to indicate the growthing of bacteria, by:
1. Forming the colony, the colony is due to the multiplication and the increasing in the
number of bacteria and aggregation is occurring. The number of bacteria in the
media is about 109 .
2. In the fluid media the appearance of turbidity makes the indication to fluid media .
d. Normal growth curve of bacterial culture
e. Decline Phase of decreasing in bacterial number why ?
3.
No division or the division is slowly rate
4. Increase in the death rate
So there are no bacteria no living bacteria in a few days.
f.
Explain briefly disinfection
Disinfection is destruction of bacteria by. a chemical agent It is destruction the mainly freeof
pathogenic. A disinfectant kills the organism rapidly but it cannot be used either internally
or externally for human beings. Disinfectants are useful for cleaning the rooms, furniture
excreta etc. Disinfection does not essentially imply the death of spores. The disinfectants
are equally lethal to pathogenic and human cells. There is no selective toxicity for pathogen
whereas the antibiotics ets.
Name some disinfectant:
Phenol
Chlorine
Formalin
Ethylene oxide
f. Antiseptic:
An antiseptic is a substance which prevents the growth of microorganism and can safely be
applied to skin, and mucous membranes.
Name some commonly used antiseptic
Cresol
Hexylresorcinol
Hexachlorophene
Tincture iodine
Iodine throat paint
Benzoic acid
Boric acid
h. Define the following:
Bactericide:
means destruction of bacteria or a method makes the destruction of bacteria.
Fungicide: means the destruction of fungi
Germicide: means the destruction of germ of bacteria, any structure
Bacteriostatic:
means the inhibition of the growth of bacteria there is no sharp line between bactericides
and bacteriostatic, phenol in 3% bactericide while in 1% bacteriostatic .
Antibiotics:
They are producing by living microorganism, most important antibiotics forming
microorganism bacteria.
Contagious disease:
It is a disease cause by microorganism which is rapidity transfers from one individual to
another by direct or indirect contact, such as tetanus is an infectious disease because it
infects the host where there is an injure while the contagious disease transfers to another
host by a direct contact .Contagious disease are all infectious diseases but all infectious
disease are not contagious diseases. .
Sporadic infection or disease:
When the disease occurs in few cases in many spaces .
Enzootic infection or disease:
When the infection occurs regularly in region.
Epizootic infection or disease:
Appearance of disease in a large number of individual infection suddenly.
Pandemic infection:
World wide infection.
Pathogenicity:
The ability of microorganism to produce an infection or disease or the ability of
microorganism to produce a different agent and symptoms
h. How the following physical agent effect on bacteria:
1. Light:
In the most power for the germs in general, sunlight is more powerful than fuse light this
dues the UVI, the UVI enters with E.N.A replication, …..UVI is mostly used for surgery, the
exposure for 5 min is enough to kill all the bacteria, infra-red rays is used in the,,,, surgery
sterilization , the infra-red rays depend on the heat ( 180 c).
2. Ionic radiation
X ray, gamma rays have a destructive action on the all cells, it makes damage to DNA of the
cells. The isotope such as a ratio active,,,,,,,, gives the gamma rays , it used in the plastic
instrument sterilization .
Electricity
It has a destructive action of bacteria due to:
1. Heat production (generated).
2. Electrolysis of the solid of media
4. Mechanical agitation:
It’s the shaking of bacteria when you make a strong shaking to the bacteria it leads to a
destruction of bacterium.
5. desiccation
It has a destruction action in present of O2 and the bacteria who lives for a long time in
absent of O when gets a desiccation so the desiccation has two actions
1-harmful in present of O 2 dues to the oxidation of bacteria.
2-Coagulation of watery sap.
6.
Action of heat
It is the most destruction agent against the most of microbes , the heat makes
coagulations to the cell membrane contains , the factor effected of heat
1. type of heat : it is two type dry, moist, the moist is more effected than dry heat due
to the present of H2O in moist so the coagulation occurs rapidly ex. :
Moist to spore 120 c for 15 -20 min
Dry heat to spore 160 c for 1 hour
2. Time and temperature
The short time needs a high temperature, so the time has an inversely proportional to the
heat.
i.
How acid and alkaline kill the bacteria?
1. acids : It leads to kill the bacteria dues to the alteration in PH
2. alkalis : Also leads to kill the bacteria due to the alteration in PH
l. effect of phenol on bacteria
It preparation of coal, it is mostly used in bacteriology lab, phenol is dissolved in water while
the cresol does not dissolve in H2O, uses
1. 1% for disinfection of hand.
2. 5% for destruction of bacteria in media.
8 – Lysol:
It has 4 times action stronger than the phenol 0.5% has disinfection for bacteria. it is ,,,,,,,,
of phenol.
m. Alcohols:
It is the common disinfectant , mostly used the absolute alcohol 95% but the better
concentration is 70% with water but less than 70% doesn’t get a disinfection .
n. Explain briefly Chemotherapeutic agent and their types:
Chemotherapeutic agent or antimicrobial chemotherapy or drugs
It means the chemical which are used to kill or inhibit the growth of microorganism which
already infected the cell of tissue or organ.
The chemotherapy is two types
1. Synthetic chemotherapeutic
2. Antibiotics produce by cells to kill the other cells.
p. Compare between antibiotics and disinfectant
The difference between the antibiotics and disinfectant and antiseptic are
1. produce by living organism an antibiotic
2. Antibiotic are selective in their action (effects on G + ve or on G –ve while
disinfectant and antiseptic effect on all organism.
3.
Antibiotic mainly is bacteriostatic while the disinfectant and septic are bactericidal
o. Antibiotics derive from fungi
The most important:
1. Penicillin:
It is discovered firstly by Fleming in 1929, he is extracted of penicillium fungi, and the
penicillin is a large group of compound gave a general form.
The radical gives the different compound of penicillium.
2 -Cephalosporin
It has the same action of penicillin it inhibits the synthesis of cell wall, it obtains from
cephalosporin, it effects on G + ve and G- ve and has the same action of Ampicillin.
3-Griscofuluvin:
It derives from penicillium griscofulvum, this drug is antifungicide it used in treatment of the
fungus.
4- Antibiotic derived from Streptomyces:
There is a large group:
1-Streptomycin
The second antibiotic group after penicillin, it is derived from Streptomyces guses, it actives
mainly against G –ve bacteria and has a weak effect on G +ve, it is active against Tubercle
bacilli.
2. Erythromycin :
It is derived from Streptomyces erythreus , it actives against G+ve, it is become the
antibiotic replaced of the ampicillin.
. Neomycin :
It is derived from Streptomyces species (unknown). It actives against G-ve, it actives against
Tubercle bacilli.
4. Kanamycin :
It's derived from Streptomyces spp, it actives against the G+ve and G-ve and also actives on
Tubercle bacilli.
s. chemically classification of Pencilline
1. penicillin has a highest activity against the G+ ve the inactivated pencillase enzyme
the group includes the penicillin G , penicillin V , benzathine.
2. Penicillin has lower activity against G + ve but it is not effected by penicillase enzyme
this group includes Methicillin, Oxacillin.
3. Penicillin acting on G+ve and G – ve bacteria and they are inactivated by penicillase
by bacteria this group includes Ampicillin, Penicillin V and penicillin, oxacillin and
Ampicillin we give all orally because it is resistance to acidity while penicillin G and
methicillin are destruct by acid.
Penicillin inhibits the synthesis of cell wall; penicillin derives from Penicillium notatum and
Penicillium chrysogenum.
Resistance of bacteria:
The microbe which resistance the penicillin produces penicillase enzyme this enzyme acts on
the penicillin and gives pencilloic acid which has no antimicrobial effect. Action of penicillin
mainly of G+ ve bacteria.
t. Enumerate Broad spectrum antibiotic :
It actives on G+ve and G-ve the most important one of these groups is:
1. Chloramphenicol :
It is derived from Streptomyces Venezuela. It active against …… for G +ve and G-VE (the size
of those bacteria smaller than the normal bacteria), mainly uses for treatment the typhoid,
paratyphoid group. Prolong of Chloramphenicol leads to aplastic anemia.
2. Tetracycline :
Tetracycline is consisting three groups:
a. oxytetracycline ( tetracycline )
b.
Chlortetracycline ( aureomycine)
c. Tetracycline (a chromycine).
The third is the most important, it produces by rechloration of chlortetracycline or
oxidation to the oxytetracycline,of tetracycline is using for treatment of cholera
v. Mode of antibiotic s against the bacteria are:
1. Antibiotics inhibit the cell wall for example penicillin
2. Antibiotics inhibit the protein synthesis for ex . all the antibiotics except polymyxin.
3. Effect the cell membrane; it makes destruction to the cell membrane for ex
polymyixin.
w. Mechanisms of bacterial resistance to antibiotics:
1. Production of pencillinase enzyme by bacteria.
2. Change the cell permeability against the drug.
3. Alteration the structural targets of the drug
4. Alteration metabolic pathway.
x. Origin of drug resistance:
1. Non genetic of drug resistance :
It produces due to
a. Dormancy of microorganism, the drug effects multiplication of bacteria, so the
bacteria put their self in dormancy state so there is no effect of drug on it.
b. Alteration in structural target:
Penicillin effects on the growing of the cell wall, so the bacteria form without cell wall and
become in a large form.
2. Genetic origin of drug resistance
It means the hereditary alteration this occur due to either
1. chromosomal:
This occurs due to the mistake in the replication so called this state (mutants).
2. extra chromosomal:
It means taken the free chromosomal by macrophage so the new chromosome alteration
the physiological and biochemical state in body this called chromosome plasmid.
y. How to derive the resistance of bacteria to Antibiotics
1.
Maintence the high level of drug in tissue and the body.
2. Administration of two drugs simultaneously.
3. Exposure of antibiotics of variable drug.
4. By apply the sensitivity test: the sensitivity of bacteria to different antibiotics called
sensitivity of bacteria.
Q Write on the following :
a. Sensitivity test of bacteria:
It is done by two methods
1. Dilution tube method
2. Disc method
b. Bacteria important steps to produce infections:
1. Entrance of bacteria inside of human or animal body.
2. Establishment and multiplication of bacteria in the host tissues.
c. bacterial routes to enter to the host body
1.
Skin:
the normal skin is a good barrier for body , most of bacteria are not able to enter
from the skin but two types of bacteria enter from the skin Brucella abortus ,
leptorspiral , where is an injure in skin the entrance of bacteria easily such as the
tetanus enters to the body through the wounds of body , some diseases occur by
animal bites such as rabies if the animal is infected . Some diseases occur by victor
insect such as the plaque of human occurs by insect of flies which transfers it from
the rates.
2. Digestive tract : It is the most common route of infection.
3. Respiratory tract ( inhalation infection)
The bacteria enter to the body by inhalation such as T.B and pneumonia.
Sometime calls
this infection droplet infection.
4. Urogenital infection :
Most important happening of urogenital disease which transfer dues to the
sexual contact such as gonorrhea and syphilis.
5. Placenta :
It is much infection to fetus from the mother for ex T.b if the mother has T.b. This
disease condition calls congenital T.B.
6. Mammary gland :
It is common infection in the animal the bacteria enter the mammary gland
through teats canal this disease calls mastitis.
7. Egg:
Entrance of bacteria through egg is important in the pullorum disease in chicks ,
the hens carry infection and multiplication in hens ovary and the egg carries the
infection so it hatch and give an infection chicken.
1. Establishment and multiplication of bacteria :
The bacteria when enter to the body is either localization or distribution in the
body and arrest I the localization or distribution Set this process calls oragantropism
(affinity of bacteria to the specific organ).
d. Oragantropism is not clear now but there are many theories:
1. Suitability of chemical composition of organ to bacteria such as erythritol is a growth
factor for brucella in the placenta, T.b and pneumonia present in lung tissue due to
present of O2.
2. Bactericidal present in some organ ,T.B when injected in rabbits and g pig , in
rabbits the T.b occurred in kidney while in G.pig there is no lesions because there
are two substances inhibits and kills T.b and these substances are :
3. Polyamine
4. Spermidine.
e. Source of infection:
There are two types:
1. Endogenous source.
It occurs due to the present of commensal bacteria in the body and alteration their
location so it gets infection. in another case when there is an assist factor such as
comes out from hot or cold suddenly this leads to rapture in …… of lung and the
phenomena coccus is growing in the amount of ……
2. Exogenous source.
There are three sources:
1. Animal and human :
a. Animal and human as a source of infection if they are infected (clinical cases).
b. Carriers (healthy cases) means an individual or a person or an animal who harbors
the pathogen organism and pass them in discharges thus consistutent in dangerous
sources of infection to others without him showing any sign or symptoms of disease
or infection .there are three types of carriers .
a.
1.
2.
3.
4.
2. Incubatory carrier :
The individual begins to excrete the microorganism during the incubation
period.
. Contact carrier :
The individual takes the microorganism from an infective case and not gets a
disease due to it is resistance but he carries the microbe to another divide.
3. Convalescent carrier :
The individual begins to excrete the microorganism during the convalescent
period.
The convalescent carrier it is the period after the recovering of disease, there are
Temporary carrier :
The infection takes a short period then gets recovery the dangerous of the carriers
are
They are not easily indicated.
They are not isolate so we cannot make a control.
Arthropod (insect).
In animal (nonliving) such as solid and fluid.