Hey all!
It’s my turn to blog again. This time, I will post on something I have learned in the Microbiology lab. It is the testing and detection of Neisseria Gonorrhoeae.
Neisseria gonorrhoeae (also known as Gonococci) is a species of Gram-negative bacteria responsible for the sexually transmitted disease Gonorrhea.
How is it detected/tested?
- To test for Neisseria gonorrhoeae, an endocervical swab is taken from the patient, then plated.
- Neisseria species is isolated from the primary culture by plating on a TM plate (selective media).
- Perform a gram-stain. Look for gram negative diplococcus (Neisseria gonorrhoeae) under the microscope.
- To further test for the presence of Neisseria gonorrhoeae, Bacticard Neisseria commercial test kit is used.
Principle of Bacticard Neisseria:
- It is used for the identification of pathogenic Neisseria species
- Kit utilizes 4 chromogenic substrates impregnated on individual test circles to detect preformed enzymes associated with pathogenic Neisseria.
- The enzymes b-galactosidase and butyrate esterase hydrolyze the substrates 5-bromo-4-chloro-3-indolyl-b-D-galactoside and 5-bromo-4-chloro-3-indolyl butyrate respectively to form a blue-green complex in the presence of oxygen.
- Gamma-glutamyl aminopeptidase hydrolyzes gamma-glutanyl-b-naphthylamide and prolylaminopeptidase hydrolyzes L-proline-b-naphthylamide and reacts with the Bacticard Neisseria Colour Developer to form a red colour.
Procedure for using Bacticard Neisseria:
- Rehydrate each test circle with 1 drop of Bacticard Neisseria Rehydrating Fluid.
- Smear several colonies of the organism to be tested across each test circle.
- Incubate at room temperature for 2 mins.
- Observe IB test circle for a blue-green colour, indicating a positive test. If positive, proceed to identification. If negative, continue incubation for additional 13 mins.
- After incubation, observe BGAL test circle for a blue-green colour indicating a positive test. If positive, proceed to identification. If negative, proceed by adding 1 drop of Colour Developer to the GLUT and PRO test circles.
- Observe for the development of a pink to red colour at 30 secs. Proceed to identification.
Interpretation of results:
- IB test
- Positive - Colour change to blue-green after 2 mins.
- Negative - No colour change.
- BGAL test:
- Positive - Colour change to blue-green within 15 mins.
- Negative - No colour change.
- GLUT and PRO test:
- Positive - Colour change to pink or red within 30 secs after addition of Colour Developer.
- Negative - No colour change.
- Neisseria gonorrhoea should show negative for IB, BGAL and GLUT tests, but positive for PRO test.
That’s all folks! Continue to enjoy your SIP while it last.
Out.
Adrian Tan
TG01
0503205G
6 comments:
hi adrian,
for each positive results from each tests, what do u meant by proceed to identification? identify what?
and what is the meaning of IB, BGAL, GLUT and PRO tests?
Ai Tee
TG 01
0503160D
Hi
Other than Neisseria gonorrhoeae, is there any microorganism which can cause gonorrhea?
You also mentioned that endocervical swab is used to culture the bacteria, and I understand that endocervical swab is for female patient. How about male patient? What kind of specimen is taken?
Thanks.
Cheers
Ye Tun
~TG01
Hi Adrian,
I would like to ask if only either one of the IB, BGAL and GLUT tests shown positive while the rest remains negative(except pro test) how would you identify whether the patient is infected with Neisseria gonorrhoea or not?
Avery
TG02
Hey Ai Tee
Since the test kit can be used to test for different bacteria in the Neisseria species, a list of the different bacteria and their expected test results is given together with the test kit for identification. What I meant by proceed to identification is for example, you obtain a positive result for IB test, you can refer to the list of bacteria, and identify which bacteria is present (single out those that will give a positive IB test). If its negative, extended incubation is required.
4 chromogenic substrates are impregnated on individual test circles.
IB - 5-bromo-4-chloro-3-indolyl butyrate
BGAL - 5-bromo-4-chloro-3-indolyl-b-D-galactoside
GLUT - gamma-glutanyl-b-naphthylamide
PRO - L-proline-b-naphthylamide
Different bacteria in the neisseria species will produce different enzymes, and these different enzymes will hydrolyze different substrates as mentioned in the posting. Hence, different bacteria will give different test results from the test circles allowing identification of the bacteria.
Hey Ye Tun
No, Gonorrhea is only caused by the gram-negative bacteria Neisseria gonorrhoeae.
For male patients, usually a urethral swab is taken. However it also depends on the type of gonorrhea. For example, for rectal gonorrhea, a rectal swab can be taken and for Gonococcal pharyngitis, a throat swab is taken.
Hey Avery
Presence of Neisseria Gonorrhoea will definitely and only show negative for IB, BGAL and GLUT, and positive for PRO. If there is any variations from this, it means that the bacteria present is not neisseria gonorrhoeae, but other pathogenic Neisseria species, since the test kit is used for the detection of other neisseria species as well.
A list of the different bacteria in the neisseria species and their expected test results is given together with the test kit for identification.
I hope these answers your questions. and sorry for the late replies =)
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