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Dr. Andrew Rynne
Dr. Andrew Rynne

Family Physician

Exp 50 years

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Is a negative ELISA test after 40 days of exposure conclusive?

Answered by
Dr. Roopa Hiremath

Infectious Diseases Specialist

Practicing since :2002

Answered : 877 Questions

Posted on Wed, 8 Jun 2016 in Infections
Question: How effective is CHLAMYDIA TRACOMATIS AND NEISSERIA GONORRHOEAE, PCR QUALITATIVE test conducted at 65 days after protected sex with CSW. report shows negative. and urine culture shows ""No Aerobic pyogenic organism grown in culture after incubation at 37°C."". I have sometimes pain in the penis, pain around umbilical area, yellow urine in the morning mainly. please guide. I did ECLIA screening for HIV on 26 and 40 days which came negative. I have attached other tests too done on 60 days..
Answered by Dr. Roopa Hiremath 1 hour later
Brief Answer:
PCR quite effective for detection of chlamydiae and neisseria

Detailed Answer:

Welcome to health care magic,

Based on the details and reports in your query, you have been screened for STDs (Sexually transmitted infections/diseases) and you are negative for all.

Chlamydia are cell wall deficient forms which do not grow so easily in routine culture media and grow only in special cell cultures. Neisseria species also need special media to isolate them like chocolate agar and Stuarts media.Hence PCR is preferred to diagnose these infections.

Moreover, you mention that you had protected sex which makes you most unlikely to have acquired any infection.

Your urine culture report indicates that you do not suffer from urinary tract infection caused by aerobic pyogenic bacteria.

Now, coming to your symptoms, I am suspecting ureteric colic which is commonly caused by the obstruction of the urinary tract by calculi or stones.
The classic presentation of a ureteric colic is acute, colicky flank pain radiating to the groin. I suggest you get a urologist opinion for the same.

I can assure you that you do not suffer from any sexually transmitted infection.

I hope I was able to clear your doubts satisfactorily,

Please get back if any more queries.


Above answer was peer-reviewed by : Dr. Prasad
Follow up: Dr. Roopa Hiremath 39 hours later
thank you doctor
I was getting mixed information that STD tests including HIV are not effective until 3 months of exposure which was really stressing me out.
Answered by Dr. Roopa Hiremath 41 minutes later
Brief Answer:
No need to worry. HIV testing for antibodies done after 3 months

Detailed Answer:

Welcome back.

I understand your anxiety regarding exposure to STDs especially HIV.

But as you have had an encounter which was protected, most unlikely chance of any infection to have occurred.

Moreover, tests for HIV antibodies can be done only after three weeks of exposure because antibodies against HIV are produced only then.

You have undergone ECLIA for HIV twice at 40th day and 60th day and both the results are negative. According to NACO guidelines if two test results for HIV are negative, HIV status is negative.

The three months period you are talking about in your query is called the window period where some individuals may give negative results for antibodies against HIV.

To rule out this period, many get a confirmatory test done after 100 days of exposure to confirm the negative status.

If you are very anxious, you can get a repeat test done on 100th day for HIV 1 and 2 antibodies.

Mind you, this test will be only be to confirm your negative status, so please do not worry unnecessarily.

I hope I have helped you with my answers.

Please get back if any more doubts.


Above answer was peer-reviewed by : Dr. Sonia Raina

The User accepted the expert's answer

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