Clobber Julius
Kill the bugs
Smash all vegetables and foodstuff that “display” religious symbols
Please add more suggestions..
Wednesday, April 28, 2010
And you though community service was a dirty word…
So you are a medical technology student? And you don’t know much? Or so you thought….
How can you do your bit for society????
Gangrene
Our grannies and grandpas love walking in the fields, doing a bit of gardening . tell them to wear shoes!
The organism that causes gangrene lives in the environment, on grasses, etc. old people usually have diabetes and hypertension. Diabetic patients usually suffer a loss of sensation, i.e. no feeling, in their fingers and toes. If they walk barefoot and get cut, the organism could enter their feet. They could end up with gangrene. They will not feel the cut, and when they do realize that they have a wound, it is quite severe. Tell them to check their feet carefully for cuts and wounds every night, or you do it for them. Another side effect of diabetes is slow healing of wounds. The high percentage of sugar or glucose in the bloodstream hinders the immune response. Exactly the reason why students who are cramming late night and eating sweets, chocolate and drinking coke, are sniffing, sneezing and coughing in the exam room. Go figure…….
Cholera
Contrary to popular belief, one doesn’t have to rush a cholera patient to the doctor for immediate medical attention. You and I could help save a life. These patients die from loss of electrolytes and dehydration. So we must replenish water together with some electrolytes. How, you ask? Silly really, just give boiled cooled water in which you dissolve a teaspoon of sugar and a of salt. And tell them not to use rivers as toilets.
Tetanus
The classic sign of tetanus is the backward arching of the body, very similar to that exhibited by the female lead in the exorcism of Emily Rose. Unfortunately by the time this is seen, it is usually fatal. Prevent tetanus by having a tetanus injection when you get cut with any sort of metal or implement. The organism responsible for tetanus is found in the environment, and needs the cut to enter your body. The effects don’t last long unlike vaccinations. Go on……teach someone
Handwashing
Good old soap and water is what we need. Soaps by nature are alkaline, they rely on anionic action to reduce surface tension to loosen dirt which is washed away by the water. Germs is just a fancy word for bacteria. We get all kinds of bacteria, like people; the bad kind and the good kind. There are millions of bacteria on the surface of our skin. They are serving a purpose there. By occupying space, they are not allowing harmful bacteria to get in. if we use antibacterial soaps, we kill the good guys and say a warm hello to all kinds of nasties. Do you want that? Go on……teach someone
Antibiotics
We all have them or know someone who does. The mother who insists you see a doctor for the flu, and as if that’s not enough, she insists that you insist on having antibiotics prescribed. Why on earth would you want antibiotics for a viral infection, cos that is what the flu is. Antibiotics are for bacterial infections, and therefore not effective against b=viruses. Well when we get the flu, our immune systems can get compromised. Then we would get a secondary bacterial infection. This would give us the yellowish phlegm, sore throat, cough, etc. the problem with antibiotics is that the doctor does not have the time to determine the best antibiotic for the cause of the bacterial infection. He just prescribes a broad spectrum antibiotic, one that would kill all or most of the bacteria. We have many friendly bacteria within us, no harm to us and we need them. Kill them and we pay the price. Wave them goodbye, cos you just killed them. A good doctor worth his title would tell you to take a live culture tablet or yoghurt with the antibiotic, to replenish the good bacteria. Many people don’t complete the course of antibiotics; they stop taking them when they start to feel better. The problem with this is that you may have killed 90% of the bacteria; the remaining 10% gets resistant to the antibiotic. If the infection doesn’t resolve, and if you go back to the doctor, you would need stronger antibiotics. And stronger antibiotics have worse side effects. Go on….. teach someone.
How can you do your bit for society????
Gangrene
Our grannies and grandpas love walking in the fields, doing a bit of gardening . tell them to wear shoes!
The organism that causes gangrene lives in the environment, on grasses, etc. old people usually have diabetes and hypertension. Diabetic patients usually suffer a loss of sensation, i.e. no feeling, in their fingers and toes. If they walk barefoot and get cut, the organism could enter their feet. They could end up with gangrene. They will not feel the cut, and when they do realize that they have a wound, it is quite severe. Tell them to check their feet carefully for cuts and wounds every night, or you do it for them. Another side effect of diabetes is slow healing of wounds. The high percentage of sugar or glucose in the bloodstream hinders the immune response. Exactly the reason why students who are cramming late night and eating sweets, chocolate and drinking coke, are sniffing, sneezing and coughing in the exam room. Go figure…….
Cholera
Contrary to popular belief, one doesn’t have to rush a cholera patient to the doctor for immediate medical attention. You and I could help save a life. These patients die from loss of electrolytes and dehydration. So we must replenish water together with some electrolytes. How, you ask? Silly really, just give boiled cooled water in which you dissolve a teaspoon of sugar and a of salt. And tell them not to use rivers as toilets.
Tetanus
The classic sign of tetanus is the backward arching of the body, very similar to that exhibited by the female lead in the exorcism of Emily Rose. Unfortunately by the time this is seen, it is usually fatal. Prevent tetanus by having a tetanus injection when you get cut with any sort of metal or implement. The organism responsible for tetanus is found in the environment, and needs the cut to enter your body. The effects don’t last long unlike vaccinations. Go on……teach someone
Handwashing
Good old soap and water is what we need. Soaps by nature are alkaline, they rely on anionic action to reduce surface tension to loosen dirt which is washed away by the water. Germs is just a fancy word for bacteria. We get all kinds of bacteria, like people; the bad kind and the good kind. There are millions of bacteria on the surface of our skin. They are serving a purpose there. By occupying space, they are not allowing harmful bacteria to get in. if we use antibacterial soaps, we kill the good guys and say a warm hello to all kinds of nasties. Do you want that? Go on……teach someone
Antibiotics
We all have them or know someone who does. The mother who insists you see a doctor for the flu, and as if that’s not enough, she insists that you insist on having antibiotics prescribed. Why on earth would you want antibiotics for a viral infection, cos that is what the flu is. Antibiotics are for bacterial infections, and therefore not effective against b=viruses. Well when we get the flu, our immune systems can get compromised. Then we would get a secondary bacterial infection. This would give us the yellowish phlegm, sore throat, cough, etc. the problem with antibiotics is that the doctor does not have the time to determine the best antibiotic for the cause of the bacterial infection. He just prescribes a broad spectrum antibiotic, one that would kill all or most of the bacteria. We have many friendly bacteria within us, no harm to us and we need them. Kill them and we pay the price. Wave them goodbye, cos you just killed them. A good doctor worth his title would tell you to take a live culture tablet or yoghurt with the antibiotic, to replenish the good bacteria. Many people don’t complete the course of antibiotics; they stop taking them when they start to feel better. The problem with this is that you may have killed 90% of the bacteria; the remaining 10% gets resistant to the antibiotic. If the infection doesn’t resolve, and if you go back to the doctor, you would need stronger antibiotics. And stronger antibiotics have worse side effects. Go on….. teach someone.
Swollen feet…. and other superstitions
Much as I hate to admit it, many superstitions are grounded in fact. Take the swollen feet one, for instance. We are told to soak swollen feet in warm salty water, the theory being that the swelling would reduce.
Here’s the scientific bit:
Water moves from an area of high concentration to an area of low concentration. An accumulation of fluid can be one reason for swelling to occur. Soaking your feet in water would cause would cause the water to move out from your feet into the warm salt water. We all know that heat would enhance the process.
The question remains:
How hot should the water be?
How much salt should be added to the warm water?
How long should you soak your feet for the procedure to be successful?
I have visions of prune like toes and other wriggly bits…….
Here’s the scientific bit:
Water moves from an area of high concentration to an area of low concentration. An accumulation of fluid can be one reason for swelling to occur. Soaking your feet in water would cause would cause the water to move out from your feet into the warm salt water. We all know that heat would enhance the process.
The question remains:
How hot should the water be?
How much salt should be added to the warm water?
How long should you soak your feet for the procedure to be successful?
I have visions of prune like toes and other wriggly bits…….
Phagocytosis (effector functions of Ab)
When phagocytosis takes place, the cell membrane of the phagocyte adheres to the cell membrane of the Ag. There are many Ag that possess structures that interfere with this adherence. Examples of these structures are capsules. In this case, the immune system compensates. It does this by forming Ab, activating complement and using cell receptors. How does it do this? Lets begin
Firstly the immune system produces a specific Ab to the Ag. This becomes an immune complex. If the Ab is either IgG or IgM, the immune complex is capable of activating complement. Remember that C’ attaches to CH2 of IgG and CH3 of IgM. When C’ is activated, the cascade results in the formation of C3b which attaches to the cell membrane of the Ag and acts as a cell receptor or cell marker. This receptor interacts with CR1 and CR3 both of which are expressed by phagocytes. Round one to the immune system.
Secondly the Fc portion of the Ab can nad does interact with phagocytes via the Fc gamma receptor found on the phagocyte. Round two to the immune system.
Remember at the beginning the Ag was all excited because it had this capsule. It was jumping all around saying; ‘ha ha ha, I have a capsule and you can’t phagocytose me!’ now its game set and match in favour of the immune system. Immune system saves the day yet again!
Firstly the immune system produces a specific Ab to the Ag. This becomes an immune complex. If the Ab is either IgG or IgM, the immune complex is capable of activating complement. Remember that C’ attaches to CH2 of IgG and CH3 of IgM. When C’ is activated, the cascade results in the formation of C3b which attaches to the cell membrane of the Ag and acts as a cell receptor or cell marker. This receptor interacts with CR1 and CR3 both of which are expressed by phagocytes. Round one to the immune system.
Secondly the Fc portion of the Ab can nad does interact with phagocytes via the Fc gamma receptor found on the phagocyte. Round two to the immune system.
Remember at the beginning the Ag was all excited because it had this capsule. It was jumping all around saying; ‘ha ha ha, I have a capsule and you can’t phagocytose me!’ now its game set and match in favour of the immune system. Immune system saves the day yet again!
Effector functions of Antibodies
The principal reason for antibodies being produced is for agglutination. When the Ab combines with the Ag, it forms an immune complex. If the Ab is either IgG or IgM, the immune complex is capable of activating complement and results in lysis of the antigen.
However Ab serve many more functions. These are the effector functions referred to in the title. The Fc portion of the Ab can attach to many cells, and bring about a specific function. The function depends on the cell it attaches to. Some of the cells that can attach to the Fc portion are neutrophils, macrophages, monocytes and trophoblasts.
Not all Ab attach to these cells. The attachment is not really so. It is more an interaction via Fc receptors. These receptors are found on the surface of cells. The Ab that interact with Fc recptors are IgG, IgM, IgE. The Fc receptor is named according to the type of Ab it interacts with. It is Fc epsilon if it interacts with IgE, Fc gamma for IgG and Fc mu for IgM.
IgA is found in the various parts of the body where mucous is secreted. Many Ag enter the body here. The Ab interferes with colonization of the Ag and therefore reduces or stops infection taking place. The Ab also reduces the infectivity of viruses.
A toxin is produced by certain bacteria once they have entered the body. The toxin is harmful and can affect the body in many ways. The immune response is to both the Ag and the toxin. Ab produced in response to the toxin are specific to the toxin. Now the toxin exerts its effect by combining with man’s tissues/cells. The actual part that comes into contact with man’s tissues is called the active site. The immune system must somehow stop the active site from coming into contact with tissue. So the Ab does this in either one of two ways. Firstly the Ab will combine with the toxin near or actually at the active site. This effectively blocks the active site. Secondly the Ab combines far from the active site, thereby causing a change in the morphology or structure of the active site. In both instances, the active site is unable to carry out its function. A point to note here is that this is an example of active natural immunity. In the case of administration of antitoxin, it is passive artificial immunity.
I will deal with immune system compensation for non adherence to phagocyte in another blog entry
However Ab serve many more functions. These are the effector functions referred to in the title. The Fc portion of the Ab can attach to many cells, and bring about a specific function. The function depends on the cell it attaches to. Some of the cells that can attach to the Fc portion are neutrophils, macrophages, monocytes and trophoblasts.
Not all Ab attach to these cells. The attachment is not really so. It is more an interaction via Fc receptors. These receptors are found on the surface of cells. The Ab that interact with Fc recptors are IgG, IgM, IgE. The Fc receptor is named according to the type of Ab it interacts with. It is Fc epsilon if it interacts with IgE, Fc gamma for IgG and Fc mu for IgM.
IgA is found in the various parts of the body where mucous is secreted. Many Ag enter the body here. The Ab interferes with colonization of the Ag and therefore reduces or stops infection taking place. The Ab also reduces the infectivity of viruses.
A toxin is produced by certain bacteria once they have entered the body. The toxin is harmful and can affect the body in many ways. The immune response is to both the Ag and the toxin. Ab produced in response to the toxin are specific to the toxin. Now the toxin exerts its effect by combining with man’s tissues/cells. The actual part that comes into contact with man’s tissues is called the active site. The immune system must somehow stop the active site from coming into contact with tissue. So the Ab does this in either one of two ways. Firstly the Ab will combine with the toxin near or actually at the active site. This effectively blocks the active site. Secondly the Ab combines far from the active site, thereby causing a change in the morphology or structure of the active site. In both instances, the active site is unable to carry out its function. A point to note here is that this is an example of active natural immunity. In the case of administration of antitoxin, it is passive artificial immunity.
I will deal with immune system compensation for non adherence to phagocyte in another blog entry
Wednesday, April 7, 2010
To think about....
Why would you recommend to a friend that he places 5, 10 and 20 cent
coins in his pet’s water bowl?
Why can someone get very ill from eating a lot of cold meats all at once?
Why is silver nitrate put into the eyes of newborns?
coins in his pet’s water bowl?
Why can someone get very ill from eating a lot of cold meats all at once?
Why is silver nitrate put into the eyes of newborns?
TRANSMISSION OF DISEASE
Categorised as either vehicle, vector and contact
Vehicle is non living
Vector is living
Contact is you know???
Mechanical vehicle is the insect itself ex allergy to bee sting
Biological vehicle is when part of life cycle of pathogen is inside insect ex malaria
Example of Waterborne vector is cholera
For pathogens to be transmitted though air, the distance must be less than 1 meter
Foodborne pathogen transmitted through cooking utensils, food itself, etc
Direct contact is kissing, sex
Indirect contact is through fomites
Droplets are when nasty people sneeze and cough directly on you
Vehicle is non living
Vector is living
Contact is you know???
Mechanical vehicle is the insect itself ex allergy to bee sting
Biological vehicle is when part of life cycle of pathogen is inside insect ex malaria
Example of Waterborne vector is cholera
For pathogens to be transmitted though air, the distance must be less than 1 meter
Foodborne pathogen transmitted through cooking utensils, food itself, etc
Direct contact is kissing, sex
Indirect contact is through fomites
Droplets are when nasty people sneeze and cough directly on you
Media tut questions
Choose the odd one out, and justify your choice
1. Peptone, asparagines, L cysteine, glucose
2. Malachite green, glycerol, asparagines, methylene blue
3. Ferric citrate, magnesium citrate, ferric ammonium citrate
4. Increased dextrose, Proteus, decrease Ph, Rhizopus
5. Rabbit blood, trimethoprim, penicillin, Bordet Gengou
6. Sterile mineral oil, closed, Pseudomonas, fermentative
7. Trimethoprim, vancomycin, nystatin, colistin
8. Ox bile, brilliant green, K tellurite, blood
9. Bile salts, ox bile, sodium citrate
10. Black colour in oxidase, acid slant in TSI, red layer at top of SIM, negative citrate
11. E coli, Klebsiella, Proteus, Salmonella
12. Bacillus, Staphylococcus, Neisseria, E coli, Klebsiella
13. Pseudomonas, E coli, Alcaligenes, Streptococcus
14. 40%KOH, alpha naphthol, MRVP, p dimethylaminobenzaldehyde, methyl red reagent
15. Pink urease, low electrolytes, PAD pos, alkaline slant
1. Peptone, asparagines, L cysteine, glucose
2. Malachite green, glycerol, asparagines, methylene blue
3. Ferric citrate, magnesium citrate, ferric ammonium citrate
4. Increased dextrose, Proteus, decrease Ph, Rhizopus
5. Rabbit blood, trimethoprim, penicillin, Bordet Gengou
6. Sterile mineral oil, closed, Pseudomonas, fermentative
7. Trimethoprim, vancomycin, nystatin, colistin
8. Ox bile, brilliant green, K tellurite, blood
9. Bile salts, ox bile, sodium citrate
10. Black colour in oxidase, acid slant in TSI, red layer at top of SIM, negative citrate
11. E coli, Klebsiella, Proteus, Salmonella
12. Bacillus, Staphylococcus, Neisseria, E coli, Klebsiella
13. Pseudomonas, E coli, Alcaligenes, Streptococcus
14. 40%KOH, alpha naphthol, MRVP, p dimethylaminobenzaldehyde, methyl red reagent
15. Pink urease, low electrolytes, PAD pos, alkaline slant
MEDIA Tuts
Explain the relationship between:
Methyl red reagent; MRVP; acidic end products; pH6; Enterobacter aerogenes
Voges Proskauer; MRVP; non acidic end products; pH4; Escherichia coli
YOU NEED TO KNOW:
MRVP is the medium. It comprises 2 tests, MR and VP.
Both tests are used to differentiate between E coli and Enterobacter aerogenes.
Both orgs degrade glucose and form by products (E coli at pH4, and Ent at pH6)
Mr tests for pH4 and VP tests for pH6. In both tests a red colour is positive.
E coli end products are called acidic
Ent end products are called non acidic.
Therefore E coli is MR pos and VP neg
Enterobacter is MR neg and VP pos
Methyl red reagent; MRVP; acidic end products; pH6; Enterobacter aerogenes
Voges Proskauer; MRVP; non acidic end products; pH4; Escherichia coli
YOU NEED TO KNOW:
MRVP is the medium. It comprises 2 tests, MR and VP.
Both tests are used to differentiate between E coli and Enterobacter aerogenes.
Both orgs degrade glucose and form by products (E coli at pH4, and Ent at pH6)
Mr tests for pH4 and VP tests for pH6. In both tests a red colour is positive.
E coli end products are called acidic
Ent end products are called non acidic.
Therefore E coli is MR pos and VP neg
Enterobacter is MR neg and VP pos
Thursday, March 18, 2010
CLED agar contd....
This is medium for the differentiation of urinary organisms. Its basic colour differs according to the manufacturer. Previously we had pale pink plates; now they are the prettiest green I've seen in a long time. Almost translucent green, like the sea on a clear summer day.
From the name, it contains cysteine, lactose and is electrolyte deficient. The electrolyte deficiency prevents swarming of .......?
LF are yellow
NLF are blue
but in addition to that.......
Pseudomanas is green with a rough colony edge
Staphylococcus aureus and Enterococcus faecalis are yellow (other Staphylococcus can be white)
From the name, it contains cysteine, lactose and is electrolyte deficient. The electrolyte deficiency prevents swarming of .......?
LF are yellow
NLF are blue
but in addition to that.......
Pseudomanas is green with a rough colony edge
Staphylococcus aureus and Enterococcus faecalis are yellow (other Staphylococcus can be white)
Wednesday, March 17, 2010
A likely story......
the following relates to the orgs we have/are studying this semester.
Mr Brown is sick. He goes to the doctor who takes a specimen. Culture reveals an org that is citrate neg, urease neg, and does not produce hydrogen sulphide. It is a Gram negative bacillus.
What reaction would it give on Mac and CLED?
Why would it not grow on MSA?
If you inoculated a TSI and SIM, would it be incorrect to say that the org is non motile, indole pos and produces an alkaline slant? Why. (explain fully)
Name the organism.
Mr Brown is sick. He goes to the doctor who takes a specimen. Culture reveals an org that is citrate neg, urease neg, and does not produce hydrogen sulphide. It is a Gram negative bacillus.
What reaction would it give on Mac and CLED?
Why would it not grow on MSA?
If you inoculated a TSI and SIM, would it be incorrect to say that the org is non motile, indole pos and produces an alkaline slant? Why. (explain fully)
Name the organism.
identification of Staphylococcus and Streptococcus
these orgs are Gram positive cocci. Strept occur either in chains or as diplococci. Staph occur in grape like clusters.
to differentiate between Staph and Strept
catalase test (3% H2O2)
Staph is pos (immediate bubbling when org is added)
Strept is neg (no immediate bubbling when org is added)
to differentiate between S aureus and S epidermidis
DNAse test (stab inoculation)
S aureus is pos (clear zone around colonies after 1N HCl is added)
S epidermidis is neg (medium turns opaque around colonies after 1N HCl is added)
Tuesday, March 16, 2010
reagents tall and ugly
Kovacs reagent for indole production
p-dimethylamino benzaldehyde
nitrate A = sulfanilic acid
nitrate B = dimethyl alpha naphthylene
VP 1 (Barritts A) = 40% KOH
VP II (Barritts b) = alpha naphthol
10 FeCl2 for phenylalanine deaminase
1N HCl for DNase
I dont have a way to remember these. If you do, please share.
p-dimethylamino benzaldehyde
nitrate A = sulfanilic acid
nitrate B = dimethyl alpha naphthylene
VP 1 (Barritts A) = 40% KOH
VP II (Barritts b) = alpha naphthol
10 FeCl2 for phenylalanine deaminase
1N HCl for DNase
I dont have a way to remember these. If you do, please share.
MR VP test
stands for methyl red and voges proskauer test
same medium ,sort of clear or colourless broth before inoculation
test is used to differentiate between E coli and Enterobacter
if E coli is positive in one test, then it will be negative in the other
add methyl red reagent to MR
look for red colour which is positive which is E coli
add VP1 and VP2 to voges proskauer
red colour is positive which is Enterobacter
methyl red
looking for breakdown of glucose to acidic end products at ph4
non acidic end products at ph 6 is negative
voges proskauer
non acidic end products at ph 6 is positive
acidic end products at ph 4 is negative
easy way to remember
acid 4 ME
(acidic end products ph 4 MR E coli)
same medium ,sort of clear or colourless broth before inoculation
test is used to differentiate between E coli and Enterobacter
if E coli is positive in one test, then it will be negative in the other
add methyl red reagent to MR
look for red colour which is positive which is E coli
add VP1 and VP2 to voges proskauer
red colour is positive which is Enterobacter
methyl red
looking for breakdown of glucose to acidic end products at ph4
non acidic end products at ph 6 is negative
voges proskauer
non acidic end products at ph 6 is positive
acidic end products at ph 4 is negative
easy way to remember
acid 4 ME
(acidic end products ph 4 MR E coli)
orgs and Gram reactions
GPC
Staphylococcus aureus/epidermidis
Streptococcus pneumoniae/pyogenes
Enterococcus faecalis
GNB
Escherichia coli
Klebsiella pneumoniae/oxytoca
Proteus vulgaris/mirabilis
Shigella sonnei
Enterobacter aerogenes
Pseudomonas aeruginosa
GNC
Neisseria
GPB
Bacillus subtilis/cereus
Staphylococcus aureus/epidermidis
Streptococcus pneumoniae/pyogenes
Enterococcus faecalis
GNB
Escherichia coli
Klebsiella pneumoniae/oxytoca
Proteus vulgaris/mirabilis
Shigella sonnei
Enterobacter aerogenes
Pseudomonas aeruginosa
GNC
Neisseria
GPB
Bacillus subtilis/cereus
SIM
used for H2S production, motility and indole production
H2S production
medium turns black
motility
organism grows outwards from line of inoculation
indole
add Kovacs reagent and look for cherry red layer at top of medium
H2S producers are motile
H2S organisms
Salmonella
Proteus
non motile
Klebsiella
Shigella
indole pos
E coli
Proteus vulgaris
Klebsiella oxytoca
Enterobacter agglomerans
H2S production
medium turns black
motility
organism grows outwards from line of inoculation
indole
add Kovacs reagent and look for cherry red layer at top of medium
H2S producers are motile
H2S organisms
Salmonella
Proteus
non motile
Klebsiella
Shigella
indole pos
E coli
Proteus vulgaris
Klebsiella oxytoca
Enterobacter agglomerans
reactions for coliforms (GNB)
UREA
pale peach to pink
Proteus is pos
Klebsiella pneumoniae is late pos
citrate
green to blue
Enterobacter aerogenes is pos
Salmonella typhimurium is pos
Proteus mirabilis is positive
phenylalanine deaminase
pale brown (like nutrient agar)
Proteus is pos (green colour after adding 10% FeCl2)
nutrient gelatin
remove after incubation and refridgerate for 20 min
Bacillus subtilis, Proteus is positive
indole
use SIM, add kovacs reagent
look for cherry red colour on top of medium
Escherichia coli, Enterobacter agglomerans, Klebsiella oxytoca are positive
motility
Klebsiella and Shigella are non motile
pale peach to pink
Proteus is pos
Klebsiella pneumoniae is late pos
citrate
green to blue
Enterobacter aerogenes is pos
Salmonella typhimurium is pos
Proteus mirabilis is positive
phenylalanine deaminase
pale brown (like nutrient agar)
Proteus is pos (green colour after adding 10% FeCl2)
nutrient gelatin
remove after incubation and refridgerate for 20 min
Bacillus subtilis, Proteus is positive
indole
use SIM, add kovacs reagent
look for cherry red colour on top of medium
Escherichia coli, Enterobacter agglomerans, Klebsiella oxytoca are positive
motility
Klebsiella and Shigella are non motile
Friday, March 5, 2010
zones of .......
there are many zones in micro. Make sure you use the correct one
zones of hydrolysis = clear zone produced by hydrolysis of some compound ex lipid
zones of sensitivity = zone of no growth around antibiotic disc
zones of resistance = zone of growth up to antibiotic disc, in effect no zone
zones of clearing = usually used when talking about DNAse activity
zones of haemolysis = clear zones produced by haemolytic orgs, usually beta haemolysis
zones of hydrolysis = clear zone produced by hydrolysis of some compound ex lipid
zones of sensitivity = zone of no growth around antibiotic disc
zones of resistance = zone of growth up to antibiotic disc, in effect no zone
zones of clearing = usually used when talking about DNAse activity
zones of haemolysis = clear zones produced by haemolytic orgs, usually beta haemolysis
nutrient gelatin hydrolysis
gelatin has properties of solids at 4 deg and liquids at 37 deg. After inoculation and incubation, all tubes are liquid. We are trying to determine whether the org produces gelatinase, which will degrade the gelatin. After removing from the incubator, place in a fridge for 20 min. REmove and then read as follows:
solid = negative for gelatinase activity
liquid = positive for gelatinase activity
NB! Even a little liquid or semi solid appearance is positive
so what happened and why??
orgs that produce gelatinase break down the gelatin, so it will not solidify at 4 deg. Gelatin will liquify at 37 deg, and solidify at 4 deg, so is solid when removed from fridge.
solid = negative for gelatinase activity
liquid = positive for gelatinase activity
NB! Even a little liquid or semi solid appearance is positive
so what happened and why??
orgs that produce gelatinase break down the gelatin, so it will not solidify at 4 deg. Gelatin will liquify at 37 deg, and solidify at 4 deg, so is solid when removed from fridge.
Tuesday, March 2, 2010
stupid ways to learn... and other tricks
so much of micro can be learnt in a few minutes. Why don't you try:
1. make crib cards with names of orgs and relevant biochemical reactions, etc
2. labelled drawings of Gram reactions, shape and arrangements
3. Create A4 pages with really important stuff and stick on places much frequented, like door of bedroom, cover of notebook, etc (nad here's a classic one that always works, back of toilet door...... you laugh!!!)
4. Sing a song of.... names of orgs in full
5. Make up swear words/phrases that incorporate all relevant biochemical reactions/ uses of media/reactions seen on media, etc
example
you mannitol CHO fermenting S aureus, salt loving halophile you
back off S epidermidis, your mother was a salt lover; you are so pathetic you can't even ferment mannitol
I am so shy I turn pink when ever Mac comes near me. He always wants me to go to that new TSI club, but I find that the fluorescent lights there make my hair turn yellow.
as Bushknife Bobby would say:
hold me hold me; You wanna dalla with my DNA broer, I'll wys u how the DNA is degraded. Warrheid, hey u choon this litie how its done. See ere, you slaan the 1N HCl there, park in the shade,broer, and then pour of the excess HCl. Now you can eyeball the darkies. I am not a skaapie, ekse!!
comments please
1. make crib cards with names of orgs and relevant biochemical reactions, etc
2. labelled drawings of Gram reactions, shape and arrangements
3. Create A4 pages with really important stuff and stick on places much frequented, like door of bedroom, cover of notebook, etc (nad here's a classic one that always works, back of toilet door...... you laugh!!!)
4. Sing a song of.... names of orgs in full
5. Make up swear words/phrases that incorporate all relevant biochemical reactions/ uses of media/reactions seen on media, etc
example
you mannitol CHO fermenting S aureus, salt loving halophile you
back off S epidermidis, your mother was a salt lover; you are so pathetic you can't even ferment mannitol
I am so shy I turn pink when ever Mac comes near me. He always wants me to go to that new TSI club, but I find that the fluorescent lights there make my hair turn yellow.
as Bushknife Bobby would say:
hold me hold me; You wanna dalla with my DNA broer, I'll wys u how the DNA is degraded. Warrheid, hey u choon this litie how its done. See ere, you slaan the 1N HCl there, park in the shade,broer, and then pour of the excess HCl. Now you can eyeball the darkies. I am not a skaapie, ekse!!
comments please
success in a microbiology practical
everytime I see certain things done by you, I cringe; and tell myself afterwards that I really must spend a lesson on "correct" etiquette, but that goes the way of all good intentions. Finally I have a way, so here goes:
read the practical guide at least once before the prac.
make short notes on what you will be doing. I am not talking about complete sentences here, but rather diagrams showing type of media, name of orgs to be used,and any other pertinent info.
bring that info with you to the prac.
nothing irritates more tha students writing down stuff from the board, with no idea of whats cutting..... oh yeah, and students not doing anything!
please remember the golden rules:
share orgs
do your own inoculations, unless told otherwise
have your own marker
don't leave stools out unless a butt is on it; thay are safety hazards
know in advance how to use slant, broth and agar plate cultures
discarding of anything
sharps in a sharp container (in not visible, ask lab technician)
glass tubes in discard basket for autoclaving and re-using
plastic tubes and agar plates in biohazard box
ask yourself: can it be washed, autoclaved and re-used? if yes, then in disinfectant jars at front of benches or discard basket. if no, then biohazard box.
unless paper towel has been used for wiping up spills, it goes into waste paper bin, not biohazard.
take or collect all your media at the beginning of the prac.
same applies for cultures.
if you do not flame your loop adequately, you will contaminate your media. Adequate means till the loop and wire portion gets red hot.
do not wander around looking lost; it only entices me to call you or ask you difficult questions.
a word of advice here:
always know what you are doing, or cultivate the art of looking like you do. If not, I will certainly notice, and then its tickets for you.
enough for now. Please could I get some comments here, if you read this? thanx, mcuh appreciated
read the practical guide at least once before the prac.
make short notes on what you will be doing. I am not talking about complete sentences here, but rather diagrams showing type of media, name of orgs to be used,and any other pertinent info.
bring that info with you to the prac.
nothing irritates more tha students writing down stuff from the board, with no idea of whats cutting..... oh yeah, and students not doing anything!
please remember the golden rules:
share orgs
do your own inoculations, unless told otherwise
have your own marker
don't leave stools out unless a butt is on it; thay are safety hazards
know in advance how to use slant, broth and agar plate cultures
discarding of anything
sharps in a sharp container (in not visible, ask lab technician)
glass tubes in discard basket for autoclaving and re-using
plastic tubes and agar plates in biohazard box
ask yourself: can it be washed, autoclaved and re-used? if yes, then in disinfectant jars at front of benches or discard basket. if no, then biohazard box.
unless paper towel has been used for wiping up spills, it goes into waste paper bin, not biohazard.
take or collect all your media at the beginning of the prac.
same applies for cultures.
if you do not flame your loop adequately, you will contaminate your media. Adequate means till the loop and wire portion gets red hot.
do not wander around looking lost; it only entices me to call you or ask you difficult questions.
a word of advice here:
always know what you are doing, or cultivate the art of looking like you do. If not, I will certainly notice, and then its tickets for you.
enough for now. Please could I get some comments here, if you read this? thanx, mcuh appreciated
Friday, February 26, 2010
orgs and their characteristics
some info for your little book::
H2S producers
Salmonella
Proteus
non motile orgs
Klebsiella
Shigella
lactose fermenters
Escherichia coli
Enterobacter aerogenes
Klebsiella pneumoniae, oxytoca
non lactose fermenters
Salmonella enteritidis, typhimurium, typhi, species
Proteus vulgaris, mirabilis
NB! I have used incorrect nomenclature rules in naming the above. Salmonella has many species, which I have separated by commas, same with Proteus.
Please remember to underline and correct spelling.
H2S producers
Salmonella
Proteus
non motile orgs
Klebsiella
Shigella
lactose fermenters
Escherichia coli
Enterobacter aerogenes
Klebsiella pneumoniae, oxytoca
non lactose fermenters
Salmonella enteritidis, typhimurium, typhi, species
Proteus vulgaris, mirabilis
NB! I have used incorrect nomenclature rules in naming the above. Salmonella has many species, which I have separated by commas, same with Proteus.
Please remember to underline and correct spelling.
CLED
CYSTEINE LACTOSE ELECTROLYTE DEFICIENT AGAR
This agar is used to differentiate between urinary orgs. The deficiency in lectrolytes prevents the swarming of Proteus species, a GNB and a member of the coliforms. The medium contains lactose which serves as a CHO (carbohydrate) source.Therefore we can get lactose fermenters - yellow colonies- and non lactose fermenters - blue colonies.
You must know what CLED stands for, the purpose of the medium and the colours of the 2 types of orgs.
This agar is used to differentiate between urinary orgs. The deficiency in lectrolytes prevents the swarming of Proteus species, a GNB and a member of the coliforms. The medium contains lactose which serves as a CHO (carbohydrate) source.Therefore we can get lactose fermenters - yellow colonies- and non lactose fermenters - blue colonies.
You must know what CLED stands for, the purpose of the medium and the colours of the 2 types of orgs.
Thursday, February 25, 2010
survival of the fittest
also known as: how to survive BMT3!!!
Keep your ears and eyes open, for news about changing timetables, pracs and lecture times. Always keep a notebook handy for scribbling down important info you may not be aware of (and your friend does!). Get and keep on the best side of all lecturers. Ho you ask??? Firstly show respect by greeting, smiling, and paying attention when they are talking. Listen and appear as if you are. Ask questions. If you have a schedule, read up on the forthcoming lecture so you can clear any doubts during the lecture itself. Don't be a smart-ass, it does not help in the long run. Speak up for yourself, no one else will. Always complete any homework given to you. Show that you care, and the lecturer will take care of you. Show that you don't care, and he will end up ignoring you.
Do some reading on your own. All the subjects are new, and require getting to grips with. Get your tongue around the new terms. Explain things to yourself. and to others. Use the lab time available to its maximum. Yes you are hungry and tired, but next week is another prac, and today will be history. You will not get another chance to look at all aspects of the techniques or to ask questions of the lecturer.
enough already. over and out
Keep your ears and eyes open, for news about changing timetables, pracs and lecture times. Always keep a notebook handy for scribbling down important info you may not be aware of (and your friend does!). Get and keep on the best side of all lecturers. Ho you ask??? Firstly show respect by greeting, smiling, and paying attention when they are talking. Listen and appear as if you are. Ask questions. If you have a schedule, read up on the forthcoming lecture so you can clear any doubts during the lecture itself. Don't be a smart-ass, it does not help in the long run. Speak up for yourself, no one else will. Always complete any homework given to you. Show that you care, and the lecturer will take care of you. Show that you don't care, and he will end up ignoring you.
Do some reading on your own. All the subjects are new, and require getting to grips with. Get your tongue around the new terms. Explain things to yourself. and to others. Use the lab time available to its maximum. Yes you are hungry and tired, but next week is another prac, and today will be history. You will not get another chance to look at all aspects of the techniques or to ask questions of the lecturer.
enough already. over and out
Tuesday, February 23, 2010
nitrate reduction test
after removing from the incubator, add solution A and B (in that order, 5 drops each) to each tube. Wait for a few minutes for the colour to develop. A red colour indicates a positive reaction, i.e. reduction of nitrate to nitrite.
zinc is added to all negative tubes. Zinc is able to reduce nitrates to nitrites, therefore a development of a red colour here indicates a negative reaction.
the tube that still shows no colour change is..... wait for it........ positive for nitrate reduction.
why you ask??????????
simply silly
because the organism reduced nitrates to ammonia gas. You could try smelling it to be sure, but I wouldn't advise it. Apart from fainting and becoming a hazard on the floor, (it's nasty down there), I can't see myself picking you up. Duh!!!!
isn't all this stuff amaaaazing!!!!
success in micro1 practical examinations
I think you and I both need this.
So what does one need to do in order to survive the prac exam?????
When you come into the lab, stop talking. You are already stressed out so you don't need to become more stressed by annoying the staff. You should have already taken out your pen or pencil, marker and labcoat, but only put on the labcoat in the lab. Don't spend time digging in your bag. Get to your place as quickly as possible.
Read through the test paper quickly and determine if you have the correct paper and all relevant documentation. Write down your name and student no.
Listen to any instructions from either the lecturer or lab technician. Check that you have heard, understood and know where all the media, cultures and apparatus are located. Ensure that you know where all the demos are positioned and have heard the instructions for the demos.
You need to organise the time available to you appropriately. Start with the procedures that require the most amount of time.
I need to organise my thoughts on this issue. Back later.
TSI contd....
I forgot to mention yesterday that the sugars in TSI are in different quantities, for a reason. Glucose is incorporated at 0.1% while lactose and sucrose are present in 1%. This is so that the orgs are forced to utilise lactose and/or sucrose after glucose is used up.
There is a systematic way of reporting the results. Remember that we are looking at and reading 4 different results, viz, acid or alkaline production in both the butt and slant, gas production and H2S production. We use the abbreviations A for acid and K for alkaline. Acid production is shown by a change in colour from red to yellow, while a change in colour to a deeper red is indicative of alkaline reaction.
All coliforms will give a positive result for glucose utilization, therefore an acid butt.
You must report acid or alkaline production in slant or butt, gas production and H2S production. An exemplar is A/A/no gas/no H2S.
Remember to give me some kind of indication of the order in which you are reporting.
see you!
Monday, February 22, 2010
TSI
Here is one of my all time favourite media, triple sugar iron. Used to differentiate between coliforms on the basis of utilization of glucose, lactose and sucrose, gas production and H2S production. The medium is an agar slant dispensed in 10 ml amounts. It is pale red in colour before inoculation.
It contains 3 carbohydrates or sugars, glucose, lactose and sucrose. Glucose is found in the butt (bottom of slant) and lactose & sucrose at the slant. utilization of any sugar results in a change in colour from pale red to yellow, which indicates acid production. An alkaline reaction is indicated by a deeper red colour.
H2S production is seen by a blackening of the medium. Gas production can be detected by any one of 3 ways:
bubbles along the tube
cracks in the medium
the entire medium moves up in the tube.
All coliforms utilize glucose. Actually if orgs had a choice between many sugars they would use glucose first, since it is easier to digest (degrade). Once the glucose has been used up, the org moves to the slant to the lactose and sucrose. If the org is a LF it utilises the lactose and sucrose; if the org is a NLF, it does not.
You can deduce the reaction an org would give on another medium based on its reaction on TSI. Try it yourself.
next time: expected reactions for coliform on TSI
format of reporting results of TSI
Lowenstein and Jensen agar
This is a mouthful!
used to culture and differentiate between species of Mycobacterium. It is said to be egg based because it uses a lot of homogenized eggs as its base. Also added are many inhibitors of growth. Mg sulphate and Mg citrate inhibit the growth of all other orgs except Mycobacterium. Malachite green inhibits any contaminants. Cycloheximide is an antifungal whilst lincoymcin and naladixic acid are antmicrobial.
You may well wonder why so many ways to prevent growth of other orgs. Simpe really. Culture of Mycobacterium requires incubation of up to 6 weeks. Imagine if both other microbes and fungi could grow uninhibited in this time. We would have to search high and low, narrow and wide, long and short to find the Mycobacteria. Remember that both fungi and regular ol' bacteria only require 18 to 24 hours to produce adequate growth. Another reason for the inhibitory substances relates to the specimen of choice, the sputum. The specimen would contain many normal flora along its route of expectoration. We don't want them!
Now the medium is pale green in colour, taken from malachite green which inhibits contaminants. It is not an agar plate, but a agar slant dispensed in small bottles with a screw top lid.
MSA
Change to microbiology here. Hope its OK?
Today we discussed media used in medical microbiology for culturing, isolating and identifying microbes of medical importance. Here is a short review of what we learnt.
MSA also known as mannitol salt agar.
used to distinguish between Staphylococcus species on the basis of mannitol fermentation, when isolated from foods, milks and clinical specimens.
The ph indicator is phenol red.
The NaCl content is moderate at 7.5 %, which makes this medium selective because it inhibits non halophiles. A halophile is an organism that is able to grow in a medium that has an increased NaCl concentration.
so this is what happens:
the organism grows, utilises the mannitol, produces waste products which in turn change the ph of the medium. This causes the ph indicator to cause a change in the colour of the medium from the original pale pink or red to yellow. Mannitol fermenting orgs either grow as yellow colonies or produce a yellow zone around the colonies. Non mannitol fermenting orgs do not utilise the mannitol therefore producing pink or red colonies. There is no associated colour change of the agar around the colonies.
can you determine the reactions shown by Staphylococcus aureus and S epidermidis?
cell markers
Lets talk about cell markers. These are "addresses" of the cells so that other cells can identify them.
Lets imagine this, ok? Say you attend a particular college or university. How would you recognize a student who attends the same? She or he would probably be travelling the same way, or be wearing the same t shirt with the college logo on it. How would you recognize a student who attends the same collge, but is registered for a programme in another faculty? Probably from the fact that you see him or her during the breaks, but not in one of your classes. Ok, so far, so good.
What about recognizing a student studying the same programme as you, but not a peer? Perhaps by their harried worried look if they are ahead of you.
By the above explanation, you can see that we use visual clues to identify people, even though we may not know them. Likewise, in the immune system, cells do not have their names printed on their surfaces, but they are still recognized by other cells in the vicinity. This is achieved by cell markers.
Now cells express all sorts of cell markers, for many different reasons. They are used to indicate the lineage of the cell, whether the cell is a naive or activated cell, or whether they are immature or mature.
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