It's a very mixed bag. Indeed there are plenty of reports alleging chlamydia has a role in some cases of chronic prostatitis, but many of them are not very convincing. Most depend on attempts to identify Chlamydia trachomatis in expressed prostate secretions (EPS), i.e. fluids expressed by pressure on the prostate during a digital (finger) rectal exam. Those fluids obviously must pass through the urethra, making it challenging to know whether a positive result really reflects infection in the prostate. Some studies reported positive results in EPS while urethral specimens were negative, which supports prostatic involvement -- but leaves lots of room for error. And many studies are quite old, using culture and not modern DNA/RNA technology. The best studies, of which there are only one or two done several years ago, used prostate biopsy, avoiding passage of fluids through the urethra. They reported small numbers of chlamydia positive results, suggesting the association with prostatitis may be real. On the other hand, other studies have shown no difference in the frequency of chlamydia in the prostate (by EPS studies, not biopsy) between men with prostatitis symptoms and others who were asymptomatic with normal prostate glands. This suggests that even if chlamydia is present, it isn't necessarily the cause of the problem.

From a treatment standpoint, it's not clear whether any of this matters. The drugs most frequently used to treat chronic prostatitis are active against chlamydia, especially levofloxacin or doxycycline. It also is clear, from the studies discussed above and many others, that many cases probably shouldn't be called prostatitis at all -- i.e. it isn't clear that the prostate is involved. This is behind the recommendation of the American Urological Association to classify apparent non-infectious cases as chronic pelvic pain syndrome (CPPS) -- although many (most?) urologists tend to continue to call such cases prostatitis. It's all very confusing, right? Antibiotic treatment almost always is tried, but makes no difference in most men's symptoms -- i.e. worth a try, but usually not effective.

Can men with apparent prostatitis but negative chlamydia tests still be harboring chlamydia in the prostate? This seems very unlikely with modern diagnostic methods:  the DNA/RNA tests (collectively called nucleic acid amplification tests, or NAATs) are exceedingly sensitive, making negative test results very reliable.* And the large majority of men with prostatitis or CPPS test negative. In the event of a positive test, treatment directed against chlamydia (especially doxycycline) is essentially 100% effective in converting test result to negative. In this circumstance, it is difficult to imagine the patient could infect his sex partner. And I am unaware of any reports of partners of men with prostatitis or CPPS testing positive for chlamydia (or gonorrhea).

Some of these same considerations apply to Mycoplasma genitalium. The results are similarly mixed, and the potential role of M. genitalium in these conditions is no clearer than for chlamydia. And it seems unlikely that fluctuating symptoms reflect the return of a previously suppressed infection. In most cases, the prostate inflammation (or whatever is causing pelvic pain) appears to have a non-infectious cause (which is presumably why antibiotics usually don't help much).

Finally turning to your specific questions:  I've never come across a patient in your situation who reported a partner who later tested positive for chlamydia or any other STI.

Having said all that, these thoughts will lead me to start an email query among some highly respected experts in both chlamydia and prostatitis/CPPS. If that results in any changes, I'll post them in a follow-up comment. In the meantime, I hope these words are helpful. Thanks again for raising the issues. Let me know if anything isn't clear.

HHH, MD

* The scientist who developed the first commercial chlamydia NAAT, ~25 years ago, claimed that the test was so sensitive that if an amount of chlamydial RNA the size of a sugar cube were diluted in Lake Michigan (she lived in Chicago), a sample of lake water would test positive. Probably it was an exaggeration, but you get the idea:  a negative NAAT is very strong evidence that C. trachomatis is absent.