Quiz feedback: Sexually transmitted infections

GP panel:

This question emphasises the importance of not making assumptions when considering any aspects of sexual health and ensuring all decisions are guided by sexual history. For example, although woman under the age of 25 years are most at risk for Chlamydia, it is worth remembering not all women will be sexually active or at increased risk. Therefore, MOH recommends opportunistic testing is targeted at women under the age of 25, who have had two or more sexual partners in the last 12 months or a recent partner change.

The panel noted 22% of their colleagues indicated they would not do Chlamydia testing following a recent partner change. There was a discussion about the reasons behind this; which may include low perceived risk by either the patient or the GP.

Once a person is found to have a positive result, the panel were aware that contact tracing remains an essential part of Chlamydia management. There are many means of contacting previous sexual partners; this may include phone, email, texting, face-to-face or letter. Patient and provider should come to an agreement of how this is best achieved. Patients can be offered the choice of either patient referral (where the patients notify their sexual contacts) or provider referral (where the health care provider agrees to undertake the task of notifying sexual contacts)

Specialist comment:

As already mentioned partner change is a risk factor regardless of perception. Another high risk group which is not discussed here are those who have been infected previously.

GP panel:

This generated an interesting discussion with the panel, as they emphasized the importance of taking a thorough sexual history, and not making assumptions about the nature of any relationship.

Generally MSM are at higher risk of STIs, due to different patterns of sexual partnering for MSM and for the heterosexual population. At the NZ Sexual Health Society conference in 2008, there was a presentation of a study² of the structure of sexual partnering among gay and bisexual men in NZ. The study revealed many MSM have high partner turnover (some have very high), partnering histories are complex for the majority of MSM and over half of MSM currently in long-term regular relationships have sex with other men.

Gonorrhoea and Syphilis are considered to be more prevalent in MSM, but the panel also queried if Chlamydia is more prevalent. The panel considered doctors may be more aware of Chlamydia in MSM due to the association with Lymphogranuloma venerum (LGV), even though the overall number of cases identified in New Zealand has been low.

LGV is another presentation of Chlamydia which should be considered in MSMs with symptomatic anorectal disease who are Chlamydia positive but not responding to normal therapy.

Specialist comment:

I am unaware of any New Zealand data relating to the prevalence of Chlamydia trachomatis ( C.trachomatis) in MSM vs MSW (men that have sex with women). Some studies have looked at C.trachomatis infection rates in males with urethritis and MSM were not significantly different to those in MSW. Another study looking at C.trachomatis infection in men with gonorrhoea found a significantly higher number of C.trachomatis infections in MSW from urethral samples (MSW 31% vs MSM 12%). In the same study 24% men with rectal Neisseria gonorrhoeae were found to be also infected with C.trachomatis.

GP panel:

Again this question generated discussion about making assumptions about sexual health. While not all people under 25 should routinely be tested for STIs, it would be reasonable to enquire about risk and offer testing.

It is reassuring to note that most GPs are aware that STIs in New Zealand are generally poorly controlled. Chlamydia in particular has been the focus of the recent MOH management guidelines¹, in an attempt to address this increasing health burden.

Most GPs are aware Chlamydia may be the cause of sterile pyruia, and that Gonorrhoea is generally not implicated in NSU (formerly known as non-gonococcal urethritis).

Specialist comment:

A study performed at Diagnostic Medlab looking for C.trachomatis in urines with sterile pyuria from patients in at risk age groups yielded about one third positive. These tests were performed on urines submitted for culture and were not therefore the ideal sample for detection of C.trachomatis. In our laboratory we occasionally isolate N.gonorrhoeae from such samples, this relies on technical staff inoculating extra media and is not recommended for detection of this organism.

GP panel:

This question provided a good opportunity to reflect on appropriate use of laboratory tests. The incubation periods for different pathogens vary, so incorrect timing of testing may provide misleading results. For example: Chlamydia is 7-21 days, Gonorrhoea is 2-5 days, Trichomoniasis is 4-28 days. It is useful to remind patients, that while laboratory tests can exclude some organisms, not all sexually transmitted infections can be excluded. In particular screening is not currently recommended for HSV and HPV.

While it is prudent to delay STI testing for approximately 2 weeks, empirical treatment may be commenced. In most cases this would be azithromycin for Chlamydia, although empirical treatment for other STIs may be indicated in high risk situations.

When a patient requests an STI test a full sexual history and examination is indicated to help determine risk and guide testing. This would typically include a swab (for women) or first void urine (for men) for Chlamydia, collection of a separate swab for gonorrhoea and trichomonas. Serology testing for HIV, hepatitis B and C, and syphilis will be guided by findings in history and examination.

Because a range of tests is indicated for patients requesting an STI check, self testing is generally not a recommended alternative. However the panel were interested to know if a self taken swab or a first void urine (FVU) for gonorrhoea is useful if a swab is refused.

Some of the panel were also familiar with practice in Australia, in which a single swab is used for both Chlamydia and gonorrhoea, and they wondered if this approach could be used in New Zealand.

Specialist comment:

The self collected vaginal swab has been found to be a more sensitive test than FVU for identifying C.trachomatis in females. Many of the nucleic acid amplification tests (NAAT) used for detection of C.trachomatis also can be used for the detection of N.gonorrhoeae but there are some issues with the specificity (false positive) tests as well as the cost. It is also not possible to perform susceptibility testing on these samples.

GP panel:

The panel was surprised that about half of their colleagues would think rectum and pharynx swabs are indicated in MSM, especially when ‘Sexual history will guide the testing’ was given as an alternative. This reinforces the importance of not making assumptions about what type of sexual activity has taken place. History taking is of key importance in situations in which you may not be familiar.

In addition, it may be worth considering that a patient presenting in this situation may have associated psychological issues that require further discussion.

Specialist comment:

Some guidelines suggest sampling urethral and rectal sites in MSM regardless of history. This relates to a number of common receptive anal sexual practices that do not constitute receptive anal intercourse but have been shown as risk activities for rectal infection³. However if none of these occurred then urethral alone would suffice.

GP panel:

The panel acknowledged that when a patient has their first outbreak of herpes, it requires sensitive management. Many patients are alarmed by the diagnosis of herpes, as there is often a stigma attached to the diagnosis; they may worry about the long term consequences, and may assume it is the result of a partner’s infidelity.

Herpes has both variable incubation and latency periods and most people are asymptomatic carriers, making it difficult to determine when it was first contracted. Furthermore, although high numbers of sexually active people are sero-postive for herpes, appropriately 80% will be asymptomatic carriers, and be unaware of their carrier status. Contact tracing is therefore not recommended for people presenting with herpes, because it is difficult to trace, and there is no recommended treatment of potential contacts.

Further STI testing will be guided by history, and depend on individual patient circumstances.

Specialist comment:

A diagnosis of genital herpes often raises many issues as the panel have discussed. It is important to remember that 20% of infections are asymptomatic 20% have typical symptoms and signs but the vast majority (60%) have atypical recurrent symptoms. Also data relating to serologically discordant couples ie 1 positive and the other negative show a seroconversion rate of about 10% per year.

GP panel:

It is clear from these responses, that GPs are aware to consider other STIs in a patient with gonorrhoea.

The panel was interested to know the prevalence of gonorrhoea in the general practice community, and the overall trends in New Zealand. They were aware that current NZ data available from ESR is predominantly from sexual health clinics, and they wanted to know if there are differences between the two.

Also, the panel were aware of the fastidious nature of gonorrhoea, and wondered if delayed transportation of swabs from GP surgeries to the laboratory would affect overall pick up rates of gonorrhoea.

Specialist comment:

The ESR data is the only all New Zealand data I know of. Recently at Medlab South we analysed the data from Nelson Marlborough, which included the community samples and the findings were consistent with the ESR. It was interesting that the majority of cases were diagnosed in GP surgeries.

Delayed transport of samples can lead to a failure to culture N.gonorrhoeae. It is therefore not ideal to have samples that will be cultured after more than 24 hours. The sooner the laboratory receives the sample the better. A gram stain of a genital swab is made in the laboratory and this helps confirm the culture result, particularly for males. As previously mentioned, NAAT testing is possible in some laboratories but although sensitivity is good, specificity is a problem as well as lack of susceptibility testing and increased cost.

GP panel:

The panel was surprised that the response rate for offering testing to all under 25 years, was not higher. Again, not all people in this group will be at risk, but at least a discussion around sexual health will need to be done, before this can be determined.

It was interesting to note the high numbers of doctors who agree that Chlamydia testing is indicated in the first trimester of pregnancy. While in the past this was not always considered, it is now recommended by the MOH, that women are tested for Chlamydia in the first trimester of pregnancy (and then again in the last trimester for those with ongoing risk factors).

The panel were familiar with the long term consequences for patients following symptomatic PID caused by Chlamydia, but they are interested in the long term consequences of asymptomatic Chlamydia.

Specialist comment:

It is difficult to give a definitive answer because the number of cases varies with the population group studied. In one study of 109 women with asymptomatic infection, 16.5% became symptomatic during 2 month follow up while 1.8% developed PID. This number has been found to be much higher if N.gonorrhoeae infection is also detected and treatment given for gonorrhoea alone, in this case 30% developed PID.