A man treated for urethral discharge returns three weeks later with identical symptoms. He completed his treatment. What is the most likely explanation? A. Antibiotic resistance B. Reinfection from an untreated partner C. Incorrect original diagnosis D. Poor compliance ANSWER: B — reinfection from an untreated partner. Why: he completed treatment and improved, then relapsed after re-exposure. This is the single commonest reason for apparent STI treatment failure. LEARNING POINT: treating the index patient alone achieves little. Contact tracing is not an administrative extra — it is what stops transmission and prevents reinfection. The partner requires treatment even if she has no symptoms at all. Resistance (A) is possible and matters for gonorrhoea, but reinfection is far commoner and should be asked about first.

Why is syndromic management used for STIs rather than waiting for laboratory confirmation? ANSWER: because a large proportion of patients never return for results, and remain infectious while waiting. TREAT AT THE FIRST VISIT, covering the organisms that commonly cause that syndrome, using the national flowchart. COST Some over-treatment. GAIN Transmission stops sooner; nobody is lost to follow-up. The trade-off is deliberate and is the point of the question. Where reliable SAME-VISIT testing exists, targeted treatment is preferable — but a flowchart that treats today beats a result nobody collects.

A patient has a widespread rash involving the PALMS AND SOLES, with fever and lymphadenopathy. He recalls a painless genital ulcer some weeks ago that healed on its own. What is the diagnosis? A. Primary syphilis B. Secondary syphilis C. Chancroid D. Genital herpes ANSWER: B — secondary syphilis. Why: the painless ulcer that healed spontaneously was PRIMARY syphilis. Weeks to months later, secondary syphilis produces a widespread rash classically involving the palms and soles, with fever and lymphadenopathy. THE TRAP IN THE NATURAL HISTORY: both stages resolve WITHOUT treatment, which convinces the patient they have recovered. The infection then enters a latent phase lasting years before tertiary cardiovascular and neurological damage appears. This is why syphilis is found by TESTING, not by waiting for complaints.

A sexually active 22-year-old woman has lower abdominal pain and vaginal discharge. What must be excluded first, and what is the threshold for treating? ANSWER: EXCLUDE PREGNANCY FIRST — ectopic pregnancy presents identically and kills. A pregnancy test comes before anything else. THEN TREAT ON SUSPICION. The threshold for treating pelvic inflammatory disease is deliberately LOW. WHY TREAT WITHOUT CERTAINTY: the clinical diagnosis is imprecise, and the cost of under-treatment is permanent — tubal damage, infertility and future ectopic pregnancy. 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 deliberate over-treatment is the correct policy.

Why does every case of congenital syphilis represent a system failure? ANSWER: because a cheap antenatal blood test plus treatment prevents it entirely. For a baby to be born with syphilis, one of these must have happened: 1. The mother never attended antenatal care. 2. She attended but was not screened. 3. She was screened but not treated. 4. She was treated but her PARTNER was not — so she was reinfected before delivery. CONSEQUENCES OF THE UNTREATED INFECTION: stillbirth, prematurity, neonatal death, and lifelong disability in survivors. Each of the four failures is a different, fixable problem — naming them is what the question is testing.

Why should an HIV test be offered to every patient with an STI? ANSWER: for two independent reasons. 1. SHARED BEHAVIOURAL RISK. Someone who acquired one sexually transmitted infection has been exposed to circumstances in which HIV also transmits. 2. BIOLOGICAL MECHANISM. Genital ULCERATION substantially increases HIV transmission in BOTH directions — it breaches the epithelial barrier and brings susceptible cells to the surface. So a genital ulcer is both a MARKER of risk and a MECHANISM of it. CONSULTATION POINT: this sits within the four C's — Compliance, Contact tracing, Condoms, Counselling.

A woman attends with vaginal discharge. Should she be managed as having a sexually transmitted infection? ANSWER: not automatically — most vaginal discharge is NOT sexually transmitted. Candida and bacterial vaginosis are commoner causes than any STI. WHY THIS MATTERS: labelling every discharge as an STI triggers unnecessary partner notification, which can cause serious harm to a relationship and, in some settings, expose a woman to violence. Assess the history and the character of the discharge, follow the national flowchart for the syndrome, and be careful with the words used when explaining the diagnosis.