Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Question For A Medical Lab Tech

  1. Jan 9, 2009 #1
    Hello everyone. I have a very important question for a medical lab technician, or someone who is familiar with Gram Stain tests.

    I recently had this test done on a penile discharge swab through our local laboratory. I do realize that this test is used to determine the presents of bacteria, however, would this test show if there was any sperm present as well? The reason I am asking is because I think I've been discharging some seminal fluid. Thanks for any help with this matter. PBD
  2. jcsd
  3. Jan 12, 2009 #2

    jim mcnamara

    User Avatar

    Staff: Mentor

    I'm not a lab tech - but gram staining is testing for bacteria - gram positive and gram negative bacteria. It is a way of identifying the bacteria, if there are any, in the urinary tract. In general antibiotics, if required, preferentially target either gram negative or gram positive bacterial infections. Gram testing is a way to help the physician prescribe medication that is effective.

    It would not show the presence of sperm. Here's why. The urine sample is cultured on media - meaning a swab of pee of put on a petri dish with growth medium, put the dish in an incubator. After a while, if there are bacterial colonies on the plate, it is an easy matter to grab a sample, put it on a slide, gram stain it, and look at it under the microscope.

    The sperm, if there were any, are long gone at this point.

    If you have concerns see your doctor.
  4. Jan 12, 2009 #3
    The first step in gram staining is growing enough bacteria from a sample to provide enough cells to stain. Sperm cells can not survive on standard agar media, so they would be dead long before any staining was done (like jim said before me) and then bacteria would completely overgrow their remains.

    After that, gram staining works on the principle of dye adhering to structures in the bacterial cell wall - peptidoglycan in gram-positive bacteria. Sperm cells don't have any peptidoglycans out there (in fact, they don't even have cell walls).
  5. Jan 14, 2009 #4
    Thank You for your replies.

    I was under the impression that a gram stain is done directly from the swab to the glass, as sort of an instant test, but am not sure, that is why I wanted a medical lab tech to reply.

    It was my doctor who took the sample, however, he is booked solid til sometime next month, so I can't get in to see him.

    This is my understanding of the situation.
    If you have a leak that is not considered normal, then it is automatically assumed that you have a bacterial infection. Therefore, the lab does the gram stain test, which is designed to determine the presence of bacteria...and just to clarify, this was not a urine sample, it was a swab taken at the tip.
  6. Jan 16, 2009 #5
    What you're discharging doesn't necessarily have to include sperm cells. If the bacteria have been messing with your prostate, then it could just be the fluid.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook