Sexually Transmitted Infections

Microbiology — Sexually Transmitted Infections, NMC MBBS licence examination syllabus (Nepal Medical Council).

Sexually Transmitted Infections: treating two people, not one

The consultation that ends with a cured patient and an untreated partner has achieved almost nothing.

A young man attends with urethral discharge. He is treated, and he gets better. Three weeks later he is back with the same complaint.

Nothing went wrong with the antibiotic. His partner was never treated, so she reinfected him — and she has meanwhile been at risk of pelvic inflammatory disease, which may cost her the ability to have children. The clinical failure was not in the prescription; it was in stopping at one patient.

This is the organising idea of the whole topic. An STI is never confined to the person in front of you, so the standard of care is not "did the patient improve?" but "has transmission stopped?"

Why syndromic management exists

In an ideal setting you would swab, culture, identify the organism and its sensitivities, and treat precisely. In practice that means asking the patient to come back — and a large proportion never do. They feel better, or the clinic is far away, or they would rather not return to a place where they were seen going in.

Meanwhile they remain infectious.

Syndromic management resolves this by treating the syndrome at the first visit, covering the organisms that commonly cause that presentation, using a national flowchart. It accepts a degree of over-treatment in exchange for treating everyone who walks through the door, once, immediately.

The trade-off is worth being explicit about, because examiners ask for it: the cost is some unnecessary antibiotic use; the gain is that transmission stops sooner and fewer people are lost to follow-up. Where reliable same-visit testing is available, targeted treatment is better — but a flowchart that treats the patient today beats a test result nobody collects.

The syndromes

🔍 What each syndrome requires you to think

Urethral dischargeIn men. Gonorrhoea and chlamydia cannot be reliably distinguished clinically and frequently coexist, so treatment covers both. Treating only one is a common cause of apparent failure.

Genital ulcerSyphilis, herpes and chancroid are the main causes, and the clinical appearance overlaps far more than textbook descriptions suggest. Any genital ulcer substantially increases HIV transmission in both directions — it breaches the barrier and draws susceptible cells to the surface.

Pelvic inflammatory diseaseLower abdominal pain in a sexually active woman. Exclude pregnancy first — ectopic pregnancy presents the same way and kills. Have a low threshold to treat: the cost of missing it is tubal damage, infertility and ectopic risk.

Vaginal dischargeThe one to be careful with. Most vaginal discharge is not sexually transmitted — candida and bacterial vaginosis are commoner. Treating every discharge as an STI causes unnecessary partner notification and real harm to relationships.

Why is pelvic inflammatory disease treated on suspicion? Because the diagnosis is clinically imprecise and the consequences of under-treatment are permanent. A course of antibiotics is a small harm; a blocked fallopian tube is not reversible. This is one of the few places in medicine where deliberately over-treating is the correct policy.

Syphilis: the infection that seems to go away

Syphilis deserves separate attention because its natural history actively misleads both patient and clinician.

Primary. A painless ulcer. Painless means ignored — and it heals by itself, which the patient reasonably takes as recovery.
Secondary. Weeks to months later, a widespread rash which characteristically involves the palms and soles, often with fever and lymphadenopathy. Highly infectious. This too resolves without treatment.
Latent. No symptoms whatsoever, for years. The patient is certain it is over. Serology still detects it.
Tertiary. Years later: cardiovascular and neurological damage, by which point treatment cannot reverse what has been destroyed.

Every stage that resolves spontaneously teaches the patient that nothing was wrong. That is why syphilis is found by testing — in antenatal clinics, in anyone with another STI, in anyone with a genital ulcer — rather than by waiting for someone to complain. A rash involving the palms and soles is the classic examination prompt.

Congenital syphilis: the preventable one

Untreated maternal syphilis crosses the placenta and causes stillbirth, prematurity, neonatal death and lifelong disability in survivors. It is one of the most damaging infections in obstetrics.

It is also almost entirely preventable by a simple, cheap antenatal blood test followed by treatment. Which leads to the point worth carrying into an exam answer:

Every case of congenital syphilis represents a failure of the system, not of medicine. Either the mother did not attend antenatal care, or she attended and was not screened, or she was screened and not treated, or she was treated and her partner was not — so she was reinfected before delivery. Each of those is a different fixable problem, and naming them shows you understand where the intervention sits.

The consultation itself

Stigma is the main barrier to STI care everywhere, and it has concrete clinical consequences. People delay attending, buy a few antibiotic tablets from a shop instead, travel to a clinic where nobody knows them, or give a false name — and crucially, they do not tell their partner.

So confidentiality here is not merely courteous; it is clinical. A private consulting space and a manner free of judgement directly determine whether the patient returns, whether they complete treatment, and whether the partner is ever treated at all.

✅ The four C's

ComplianceMake sure the treatment will actually be completed — explain it, and prefer regimens the patient can finish.

Contact tracingThe partner needs treatment even if entirely asymptomatic, or the patient is reinfected. This is the step most often omitted.

CondomsProvide them, and explain their use for preventing reinfection and onward spread during and after treatment.

CounsellingIncluding offering an HIV test — an STI is a marker that the person has been exposed to transmission risk.

Why offer an HIV test to everyone with an STI? Two reasons. The behavioural risk is shared, so someone who acquired one infection may have been exposed to the other. And biologically, genital ulceration substantially increases HIV transmission in both directions — so an ulcer is both a marker of risk and a mechanism of it.

Two situations that change the consultation

A young person below the age of consent. An STI in a child or young adolescent raises the possibility of sexual abuse and triggers safeguarding obligations. This is not a judgement about the young person; it is a duty to consider how the infection was acquired.

Suspected coercion or violence. Ask, privately and without the partner present. The safeguarding and mental health chapters cover the response; the point here is that an STI consultation is one of the few reliable opportunities to ask the question at all.

Putting it together

Treat the syndrome at the first visit, because many patients never return for results — and treat the partner, or you have achieved nothing.
Urethral discharge means covering both gonorrhoea and chlamydia. They coexist and cannot be told apart clinically.
Treat suspected pelvic inflammatory disease rather than waiting for certainty — but exclude pregnancy first.
Most vaginal discharge is not an STI.
Syphilis resolves spontaneously at each stage and returns years later, so it is found by testing, not by symptoms. Palms and soles.
Congenital syphilis is a system failure — antenatal screening plus partner treatment prevents it.

No regimens, doses or serological cut-offs are given here. STI treatment changes with resistance patterns and is set nationally — use your current national guideline, and check it rather than recalling it.

Syllabus points

Why syndromic management exists and its trade-off
Urethral discharge — cover gonorrhoea and chlamydia
Genital ulcer and the link with HIV transmission
PID — exclude pregnancy, then treat on suspicion
Vaginal discharge is often not an STI
The stages of syphilis; palms and soles
Congenital syphilis as a system failure
The four C's and offering an HIV test

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