@Patrick Tracy Hii! May I ask how to count the colony if we did not use any dilution? That's why we cannot use the CFU/ml, we are having a hard time to compute for it. Here's what we did. We get the sample from the keyboards using cotton swab then we directly streak it to MSA.
The CFU/ml is a standardized system based on a liquid volume, namely urine. You are using a cotton swab to collect a dry sample, so you cannot use that system. I don't know how you would do a colony count in your situation.
My culture test says "No microorganism seen" in the gram stain. However, the C/S Bact PF identified the presence of coagulase negative staphylococcus with "growth isolated after 24 hours from bottle." The bacterial count is N/A and there is "no growth on primary isolation for colony count." Can somebody explain?
What if a symptomatic patient's urine culture does not does not fall within the range to justify an "infection"? Are there uti-causing bacteria that will not grow in a standard urine culture? Are there other tests out there that can detect infectious organisms in urine? Thank you!!
Positive urine cultures fall into three categories: colonization, infection and contamination. It is up to each facility to determine the parameters for when these cultures are worked up and how they are reported out. If a urine culture is positive, but not worked up, it will typically be held for a certain amount of time (3-7 days), so the physician can still call the micro lab and ask that it be worked up. A clean catch specimen growing 10-20,000 CFU/uL of a single isolate may be viewed as colonization and not be worked up. It may receive the following report "10-20K probable E. coli. Plate held for 5 days". However, if it is a catheterized specimen, it will probably be viewed as infection and get a full workup. There is a general rule in microbiology about working up cultures in relation to how many organisms are present. Urine is a sterile body fluid, so if there are three of more colonies types on the plates, it will probably be viewed as contamination and not be worked up. It may receive a report like "50-100,000 CFU/uL of mixed gram-positive flora. Plate held for 5 days".I will let you do the research on bacteria that will not grow on standard media and emerging detection technologies. You shouldn't have any problems finding material on them.Good luck
This is the issue with standard cultures. They report back as mixed flora if you have multiple pathogens, and doctors read that as normal. This happened to me multiple times with a pseudomonas, enteroccocus, Candida infection. Luckily I found Pathnostics testing, and they were able to properly report it. I wish they would do away with this standard urine culture.
hello , thank you so much for your videos its so helpful . I have a question , why do you count on blood agar , and not on macconkey agar or others agar !? Thank you .
@@patricktracy9947 thank you for responding . So you can count on any plate but the type of steaking is diffrent , it's not but quadrant , am i right ?
@@staisi2012 You can count plates if a calibrated loop is used to set them up. Urine cultures are usually the only culture type that use a calibrated loop. Other culture types like sputum where we don't use a calibrated loop and just streak for isolation may use a system of quantitation like "rare, few, moderate or many".
Really appreciate your video! I have a question though. What is the impact if in doing a Gram stain, the decolourizer is not rinsed with water before adding safranin, I.e., decolourizer is just drained from the slide?
Hi Paula, I always rinse with water after each chemical in the Gram stain is added. In the case of the decolorizer, I rinse almost immediately. The decolorizer can be alcohol, acetone, or more commonly a combination of both and really should be rinsed away before applying the safranin. In my experience, the more acetone there is, the quicker the decolorizer works and therefore the sooner it needs to be thoroughly rinsed off the slide.
@@patricktracy9947 hello sir, can you make a video of your technique, how you do the urine culture in the biplate please? Or let me know of sources where I could see how to do it please?I'm having trouble doing the pattern close together without the streaks overlapping thank you in advance
@@pedrohernandez2917 Hi Pedro, urine cultures will often have a sheep-blood plate and a CNA/MacConkey bi-plate. The bi-plate is so we can differentiate which organism(s) is in the patient's urine. Gram-positive bacteria and yeast will grow on the CNA and Gram-negative rods (E. coli) will grow on the MacConkey. The sheep blood plate is used to perform the colony count. Both Gram-positives and Gram-negatives will grow on the sheep-blood plate. I will try to insert a link below to a good video to see how these plates are set up.
In these videos I am just focusing on reading the plates. That is a huge step for students going into their microbiology clinical rotations. It's one thing to look at a pure culture of Haemophilus influenzae on a chocolate plate, but it is something entirely different trying to find it on a sputum culture with three types of media.
Yes, gram-positive bacteria grow on CNA, but yeast grow on it too. It is very difficult to differentiate colonies of yeast from colonies of gram-positive bacteria. That is why we do a gram stain.
The oxidase test is used to differentiate members of the family Enterobacteriaceae from other similar gram-negative rods. Almost all members are oxidase negative.
For urine cultures, typically a calibrated loop is used to streak the plates. There are two sizes commonly used: 0.01 and 0.001 ml. The second is the one I used in the video. For every colony on the plate, we say there is 1000 colony forming units per milliliter. If there are 20 colonies, it is reported out as 20,000 CFUs/ml. This is a system used so physicians can get an idea of how much bacteria is present. Based on the number of bacteria present, the physician may be able to determine if the bacteria is due to infection, colonization or contamination. How bacteria gets worked up depends on how the urine is collected: by the midstream, catheter or suprapubic aspirate.
@@patricktracy9947 Thank you for the video and explanation. So if we used 0.01 ml calibrated loop, and the colony count is 20 colonies, it means 20 x 100 = 2,000 CFUs/mL ? Thank you for your response..
@@djvlmonia Each lab will have a standard operating procedure (SOP) for each test. For a urine culture, the colony count is used to guide the provider (doctor) about a patient's urinary tract infection (UTI). Zero colonies would be no growth, so probably no organisms present. Furthermore, an SOP may say that 10-20,000 CFUs/ml is colonization, and that greater than 20,000 is an infection. The more colonies present tells the provider that more than likely the patient has an active UTI, not just colonization.
ua gn ua gp ua many setup: sba: streak for count: >100,000 cfu/ml mmac/cna: no growth on cna; lactose pos on Mac Mac: selective for gno: differential for lactose fermentation /cna: cna (selective differ for gpo and yeasts) differential for hemolysis calibrated loop: 1/100 or 1/1000 ml loop report: >100,000 cfu how to work it up: indwelling catheter, suprabuppic aspirate; oxidase test: read of... oxidase neg Media: report: is it contamination, infection or.... >100,000 cfu/ml of probable ecoli id/susp to follow Ecoli: no 1 infection in women. How to QC plates: ====================================================== ua 2nd sample Mac cna selective for gpo and yeasts sba: count >100,000 cfu/ml work it up if gpo that are pathogens in ua: staph saprophyictus, yeast, enteropathogens see feet in this plate. work it up as yeast. gs: and work it up; f? yesasts Preliminary report: >100,000 yeast; id to follow ==================================== Plate Reading - Urine II ua-cam.com/video/SLFd7Yr2hwk/v-deo.html
ua gn ua gp ua many setup: sba: streak for count: >100,000 cfu/ml mmac/cna: no growth on cna; lactose pos on Mac Mac: selective for gno: differential for lactose fermentation /cna: cna (selective differ for gpo and yeasts) differential for hemolysis calibrated loop: 1/100 or 1/1000 ml loop report: >100,000 cfu how to work it up: indwelling catheter, suprabuppic aspirate; oxidase test: read of... oxidase neg Media: report: is it contamination, infection or.... >100,000 cfu/ml of probable ecoli id/susp to follow Ecoli: no 1 infection in women. How to QC plates: ====================================================== ua 2nd sample Mac cna selective for gpo and yeasts sba: count >100,000 cfu/ml work it up if gpo that are pathogens in ua: staph saprophyictus, yeast, enteropathogens see feet in this plate. work it up as yeast. gs: and work it up; f? yesasts Preliminary report: >100,000 yeast; id to follow ====================================
I get it now. You are a good teacher. You made me understand by this video. Thank you sooo much!!!
You're welcome...glad it was helpful.
Thank you very very much ... I have a crappy tutor in my internship & your videos are huuuuuuuuge help ..
Omg same they literally suck
This is great, a good quick review for my micro class!
Glad to hear that it was helpful.
great video sir... please do more reading cultures videos
I will see what I can do. Thank you
@Patrick Tracy Hii! May I ask how to count the colony if we did not use any dilution? That's why we cannot use the CFU/ml, we are having a hard time to compute for it. Here's what we did. We get the sample from the keyboards using cotton swab then we directly streak it to MSA.
The CFU/ml is a standardized system based on a liquid volume, namely urine. You are using a cotton swab to collect a dry sample, so you cannot use that system. I don't know how you would do a colony count in your situation.
Toooo good
Thanks Sir Patrick.. I needed your videos so much... 🙌🏻
Thank you...I am glad they were helpful.
I love this demonstration
Thank you...I hope it was helpful.
Please can you show other tests and how you inoculated and all for better understanding
I have videos of many different tests used in microbiology.
My culture test says "No microorganism seen" in the gram stain. However, the C/S Bact PF identified the presence of coagulase negative staphylococcus with "growth isolated after 24 hours from bottle." The bacterial count is N/A and there is "no growth on primary isolation for colony count." Can somebody explain?
The information you have given seems to be related to a blood culture, not urine.
Excellent tutorial, thank you!
Nice 👍
What if a symptomatic patient's urine culture does not does not fall within the range to justify an "infection"? Are there uti-causing bacteria that will not grow in a standard urine culture? Are there other tests out there that can detect infectious organisms in urine? Thank you!!
Positive urine cultures fall into three categories: colonization, infection and contamination. It is up to each facility to determine the parameters for when these cultures are worked up and how they are reported out. If a urine culture is positive, but not worked up, it will typically be held for a certain amount of time (3-7 days), so the physician can still call the micro lab and ask that it be worked up. A clean catch specimen growing 10-20,000 CFU/uL of a single isolate may be viewed as colonization and not be worked up. It may receive the following report "10-20K probable E. coli. Plate held for 5 days". However, if it is a catheterized specimen, it will probably be viewed as infection and get a full workup. There is a general rule in microbiology about working up cultures in relation to how many organisms are present. Urine is a sterile body fluid, so if there are three of more colonies types on the plates, it will probably be viewed as contamination and not be worked up. It may receive a report like "50-100,000 CFU/uL of mixed gram-positive flora. Plate held for 5 days".I will let you do the research on bacteria that will not grow on standard media and emerging detection technologies. You shouldn't have any problems finding material on them.Good luck
@@patricktracy9947 thank you!!
Amber I just noticed that I used CFU/uL, but it should be CFU/mL.
This is the issue with standard cultures. They report back as mixed flora if you have multiple pathogens, and doctors read that as normal. This happened to me multiple times with a pseudomonas, enteroccocus, Candida infection. Luckily I found Pathnostics testing, and they were able to properly report it. I wish they would do away with this standard urine culture.
hello , thank you so much for your videos its so helpful .
I have a question , why do you count on blood agar , and not on macconkey agar or others agar !?
Thank you .
There is no reason why you can't count colonies from the MacConkey or CNA plates.
@@patricktracy9947 thank you for responding .
So you can count on any plate but the type of steaking is diffrent , it's not but quadrant , am i right ?
@@staisi2012 You can count plates if a calibrated loop is used to set them up. Urine cultures are usually the only culture type that use a calibrated loop. Other culture types like sputum where we don't use a calibrated loop and just streak for isolation may use a system of quantitation like "rare, few, moderate or many".
@@patricktracy9947 I understand sir , thank you so much , i really appreciate it .
7:24 but these are LF colonies why we do oxidase test on these....we only do on NLF plz clear your point
Really appreciate your video! I have a question though. What is the impact if in doing a Gram stain, the decolourizer is not rinsed with water before adding safranin, I.e., decolourizer is just drained from the slide?
Hi Paula, I always rinse with water after each chemical in the Gram stain is added. In the case of the decolorizer, I rinse almost immediately. The decolorizer can be alcohol, acetone, or more commonly a combination of both and really should be rinsed away before applying the safranin. In my experience, the more acetone there is, the quicker the decolorizer works and therefore the sooner it needs to be thoroughly rinsed off the slide.
@@patricktracy9947 hello sir, can you make a video of your technique, how you do the urine culture in the biplate please? Or let me know of sources where I could see how to do it please?I'm having trouble doing the pattern close together without the streaks overlapping thank you in advance
@@pedrohernandez2917 Hi Pedro, urine cultures will often have a sheep-blood plate and a CNA/MacConkey bi-plate. The bi-plate is so we can differentiate which organism(s) is in the patient's urine. Gram-positive bacteria and yeast will grow on the CNA and Gram-negative rods (E. coli) will grow on the MacConkey. The sheep blood plate is used to perform the colony count. Both Gram-positives and Gram-negatives will grow on the sheep-blood plate. I will try to insert a link below to a good video to see how these plates are set up.
ua-cam.com/video/eVh_YPNr6lI/v-deo.html
Thanks i learn many things
Can we culture urine directly like csf and sputum samples before inoculating on the plates first.
Is it really gram stained at all?
I am not sure what you mean by culturing urine directly before inoculating the plates. Urine is not usually Gram stained directly like CSF and sputum.
What about the biochemical tests.... you didn't show how to do it
In these videos I am just focusing on reading the plates. That is a huge step for students going into their microbiology clinical rotations. It's one thing to look at a pure culture of Haemophilus influenzae on a chocolate plate, but it is something entirely different trying to find it on a sputum culture with three types of media.
Why do u need a gran test if C&A is already telling us that its Gram +ve?
Yes, gram-positive bacteria grow on CNA, but yeast grow on it too. It is very difficult to differentiate colonies of yeast from colonies of gram-positive bacteria. That is why we do a gram stain.
Please help us, we really need your help. Thank you in advance.
Can you please recommend me book which you are following
I use Bailey & Scott's Diagnostic Microbiology
What is the purpose of oxidase test?
The oxidase test is used to differentiate members of the family Enterobacteriaceae from other similar gram-negative rods. Almost all members are oxidase negative.
good sh*t
Oh thanks! Hi Constance. Probably not the place to chat. Send me an email and let me know how things are.
THANK YOU! My instructor is terrible!
I am sorry to hear that.
how to report 100 colonies as 100,000 CFU/ml ? explains sir
For urine cultures, typically a calibrated loop is used to streak the plates. There are two sizes commonly used: 0.01 and 0.001 ml. The second is the one I used in the video. For every colony on the plate, we say there is 1000 colony forming units per milliliter. If there are 20 colonies, it is reported out as 20,000 CFUs/ml. This is a system used so physicians can get an idea of how much bacteria is present. Based on the number of bacteria present, the physician may be able to determine if the bacteria is due to infection, colonization or contamination. How bacteria gets worked up depends on how the urine is collected: by the midstream, catheter or suprapubic aspirate.
@@patricktracy9947 Thank you for the video and explanation. So if we used 0.01 ml calibrated loop, and the colony count is 20 colonies, it means 20 x 100 = 2,000 CFUs/mL ? Thank you for your response..
@@baskorojusticia2964 That is correct.
@@patricktracy9947 how do we know if it is colonization or contamination based on the colony count?
@@djvlmonia Each lab will have a standard operating procedure (SOP) for each test. For a urine culture, the colony count is used to guide the provider (doctor) about a patient's urinary tract infection (UTI). Zero colonies would be no growth, so probably no organisms present. Furthermore, an SOP may say that 10-20,000 CFUs/ml is colonization, and that greater than 20,000 is an infection. The more colonies present tells the provider that more than likely the patient has an active UTI, not just colonization.
Please something you need to speed up a little bit, the talking is something too much, pls go straight to the point.
ua gn
ua gp
ua many
setup:
sba: streak for count: >100,000 cfu/ml
mmac/cna: no growth on cna; lactose pos on Mac
Mac: selective for gno: differential for lactose fermentation
/cna: cna (selective differ for gpo and yeasts) differential for hemolysis
calibrated loop: 1/100 or 1/1000 ml loop
report: >100,000 cfu
how to work it up: indwelling catheter, suprabuppic aspirate;
oxidase test: read of...
oxidase neg
Media:
report: is it contamination, infection or....
>100,000 cfu/ml of probable ecoli
id/susp to follow
Ecoli: no 1 infection in women.
How to QC plates:
======================================================
ua 2nd sample
Mac
cna selective for gpo and yeasts
sba: count >100,000 cfu/ml work it up
if gpo that are pathogens in ua: staph saprophyictus, yeast, enteropathogens
see feet in this plate. work it up as yeast.
gs: and work it up; f? yesasts
Preliminary report: >100,000 yeast; id to follow
====================================
Plate Reading - Urine II ua-cam.com/video/SLFd7Yr2hwk/v-deo.html
ua gn
ua gp
ua many
setup:
sba: streak for count: >100,000 cfu/ml
mmac/cna: no growth on cna; lactose pos on Mac
Mac: selective for gno: differential for lactose fermentation
/cna: cna (selective differ for gpo and yeasts) differential for hemolysis
calibrated loop: 1/100 or 1/1000 ml loop
report: >100,000 cfu
how to work it up: indwelling catheter, suprabuppic aspirate;
oxidase test: read of...
oxidase neg
Media:
report: is it contamination, infection or....
>100,000 cfu/ml of probable ecoli
id/susp to follow
Ecoli: no 1 infection in women.
How to QC plates:
======================================================
ua 2nd sample
Mac
cna selective for gpo and yeasts
sba: count >100,000 cfu/ml work it up
if gpo that are pathogens in ua: staph saprophyictus, yeast, enteropathogens
see feet in this plate. work it up as yeast.
gs: and work it up; f? yesasts
Preliminary report: >100,000 yeast; id to follow
====================================