Sexually transmitted infections

 

Chlamydia

Chlamydia is the most common curable STI diagnosed in the UK. Often asymptomatic, anyone who is sexually active is considered to be at increased risk of chlamydia infection. It is the most commonly recognised, screened and treated of all STIs.

Allow 6 weeks before re-testing to avoid picking up the DNA from a previous infection.

 

Chlamydia CT
Type: Bacterial
Incubation period: 1–3 weeks, up to 6 weeks
Sample site: Urine; Cervix/Vagina; Cervix/Vagina

 

CT/GC Combined
Type: Bacterial
Incubation period: 1–3 weeks, up to 6 weeks
Sample site: Urine; Cervix/Vagina; Cervix/Vagina; Rectum; Throat

 

Gonorrhoea 

Gonorrhoea is caused by the bacterium Neisseria gonorrhea, which multiplies easily in the mucous membranes of the male and female reproductive tract. It can cause serious and permanent health conditions if not treated. Symptoms of gonorrhoea are usually overt in men with white, yellow, or green discharge from the penis. Gonorrhoea can also infect the throat and rectum – individual PCR swabs from each site should be taken to screen for gonorrhoea. Resistance to antibiotics is increasing, and treatment is now combined oral and injectable antibiotics.

Partners should be treated at the same time with retesting after two weeks to confirm clearance – test of cure is recommended following treatment for gonococcal infections. 

 

Gonorrhoea GC
Type: Bacterial
Incubation period: 2–7 days, up to 1 month
Sample site: Urine; Cervix/Vagina; Cervix/Vagina; Cervix / Vagina

 

CT/GC Combined
Type: Bacterial
Incubation period: 1–3 weeks, up to 6 weeks
Sample site: Urine; Cervix/Vagina; Cervix/Vagina; Rectum; Throat

 

Mycoplasma genitalium (M.gen)

Mycoplasma genitalium (M.gen) is an important sexually transmitted pathogen detectable only by NAAT. M.gen lacks a cell wall and has limited treatment options. It spontaneously develops resistance to antimicrobials. BASHH recommends treatment with Resistance Guided Therapy – testing for M.gen with macrolide resistance determination. M.gen cannot be cultured for diagnostic testing. M.gen prevalence is higher than GC, and in some populations can be similar to CT.

M.gen risk factors are similar to CT and consider testing M.gen in all males with non-GC urethritis and all individuals with signs or symptoms of PID, cervicitis, endometritis, associated infertility, ano-rectal condition or epididymo-orchitis. Partner testing is advised for current partners only. Rectal infections are common, and appear to be an important reservoir for resistance. BASHH guidance – all patients must return for test of cure at 3-5 weeks.

 

Mycoplasma genitalium
Type: Bacterial
Incubation period: Symptoms develop at 1–3 weeks
Sample site: Urine; GU Site; Cervix/Vagina

Macrolide Resistance Testing (M.gen)

Prevalence of Mycoplasma genitalium (M.ge)n in men and women in the general population is 1-2%. It has been implicated as a cause of acute and chronic non-chlamydial non-gonococcal urethritis in males and post coital bleeding, cervicitis, endrometritis and pelvic inflammatory disease in females. It is a sexually transmitted, fastidious microorganism that is extremely difficult to culture – with nucleic acid amplification testing (NAAT urine or swab) being the only method available for routine M. genitalium detection. Macrolides are generally considered the first-line treatment for M. genitalium infections. However, resistance to macrolides seems to be increasing worldwide typically exceeding > 40% in male patients who are detected positive for M.gen at screening.

M.gen can be requested as a single PCR test or with CT/GC, with or without other testing options. Important updates to the UK BASHH M. genitalium management guidelines are taking the issue of antimicrobial resistance seriously. The draft guidelines have been posted for consultation and include a grade 1B recommendation to test for antimicrobial resistance, stating the importance of knowing the macrolide resistance status to determine whether azithromycin should be prescribed. The guidelines aim to support laboratories in making a case for increased funding to bring in the necessary testing to manage M. genitalium infections and associated antimicrobial resistance.

 

Ureaplasma 

U. Urealyticum and parvum are strains of bacteria that can lead to urinary tract infection and pelvic inflammation. Usually asymptomatic, it is part of the normal genital flora of both men and women. It is found in about 70% of sexually active humans. In males with lower sperm quality, ureaplasma infection could lead to a more pronounced decreased in some seminal parameters and compromise sperm motility. 

 

Ureaplasma urealyticum
Type: Bacterial
Incubation period: Symptoms develop at 1–3 weeks
Sample site: Urine; GU Site; Cervix/Vagina

 

Trichomoniasis 

Trichomoniasis is caused by a tiny parasite called Trichomonas vaginalis – and is one of the most common STIs worldwide. Frequency of coinfection with other STIs is well recognised, and notably, infection increases the risk of HIV transmission in both men and women. It is associated with adverse pregnancy outcomes, infertility, and cervical neoplasia.

Some women may mistake this infection for a yeast infection or bacterial vaginosis since the symptoms are similar: frothy discharge, strong vaginal odour, pain on intercourse, irritation and itching. Men can get trichomoniasis too, but they don’t tend to have symptoms. It seems to be linked to male factor infertility. Partners (male or female) need to be treated to avoid ongoing re-infection. Infected women who are sexually active have a high rate of reinfection, thus re-screening at 3 month post treatment could be considered.

 

Trichomonas vaginalis
Type: Parasitic
Incubation period: 4–28 days, many patients are asymptomatic carriers
Sample site: Urine; GU Site; Cervix/Vagina

 

Gardnerella vaginalis

Gardnerella vaginalis is a bacterium rather than a sexually transmitted infection. It is part of the normal vaginal flora but, when the normal balance of bacteria in the vagina is disrupted, it can flourish and overgrow leading to bacterial vaginosis. Does it matter if it not an STI? Yes, because it can be characterised by a fishy smelling, white vaginal discharge, itching, burning, and irritation, and there are some known pregnancy and pelvic inflammatory conditions associated with Gardnerella as well as a higher risk of getting other STI’s. 

In a patient with signs and symptoms suggestive of bacterial vaginosis detection of G. vaginalis provides supportive evidence of bacterial vaginosis. It can, however, be detected in asymptomatic individuals and it can also be absent in patients with bacterial vaginosis which has been caused by overgrowth of other similar organisms such as Mobiluncus and Atopobium species. Results should be interpreted in line with patient’s clinical symptoms and microscopy.

 

Gardnerella vaginalis
Type: Bacterial
Incubation period: Imbalance of normal flora
Sample site: Urine; GU Site; Cervix/Vagina

 

Herpes/Herpes Simplex Virus I/II

Genital herpes caused by the herpes simplex virus (HSV). The virus lives in the nerves and when active it travels to the surface of the infected area and makes copies of itself – called shedding, because new virus cells can at this time rub off onto another person. The virus travels back down the nerve to a ganglion usually at the base of the spine where it lies dormant for a while. It causes painful blisters on the genitalia and surrounding areas. It can be passed through intimate sexual contact and for this reason is referred to as an STI. Once infected, it remains a chronic long term condition with the virus remaining with recurrent activity with variable frequency.

There are two types of herpes simplex virus: Type I and Type 2. Both are highly contagious and can be passed easily from one person to another. There is no cure for genital herpes, the symptoms can usually be controlled by antiviral medication. Although using a condom can reduce the risk of herpes transmission, condoms are not 100% effective as herpes can be spread from skin-to-skin.

 

Herpes Simplex Virus I/II
Type: Viral
Incubation period: 2–14 days. Testing is most appropriate for patients with symptomatic lesion(s)
Sample site: Herpes lesion

 

 

Lymphogranuloma venereum (LGV)

LGV is a type of chlamydia bacteria that attacks the lymph nodes. It is seen predominantly in gay and bisexual men, and very rarely seen in the UK in heterosexual men and women.

Nearly all LGV infections seen in the UK in recent years have been in the rectum. Within a few weeks of becoming infected, most people get painful inflammation in the rectum with bleeding, pus, constipation or ulcers, sometimes with fever, rash and groin, armpit or neck swelling. Left untreated, LGV can cause lasting damage to the rectum that may require surgery. LGV in the penis might cause a discharge and pain when urinating, with swollen glands in the groin. LGV in the mouth or throat is rare but can cause swollen glands
in the neck.

Investigation for possible LGV symptoms is by PCR swab taken from the rectum and penis. If LGV infection is suspected in female patients, cervical and vaginal PCR swabs should be taken. Samples are first tested for chlamydia and if chlamydia is detected, if LGV is suspected, swabs can be further tested, if requested, for LGV as an additional tests, using the same swab samples. Sexual contact partners should also be checked.