Plate Reading - Urine I 

You're welcome...glad it was helpful.

Omg same they literally suck

Glad to hear that it was helpful.

I will see what I can do. Thank you

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.

I have videos of many different tests used in microbiology.

The information you have given seems to be related to a blood culture, not urine.

Thank you...I hope it was helpful.

Thank you...I am glad they were helpful.

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 .

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.

ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-eVh_YPNr6lI.html

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.

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.

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.

I use Bailey & Scott's Diagnostic Microbiology

The oxidase test is used to differentiate members of the family Enterobacteriaceae from other similar gram-negative rods. Almost all members are oxidase negative.

I am sorry to hear that.

Oh thanks! Hi Constance. Probably not the place to chat. Send me an email and let me know how things are.

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.