Introduction

Learning objectives

Understand that STIs can be caused by bacteria, viruses, or protozoa and that many are asymptomatic.
Incorporate the five key questions when facing a possible STI.
Understand that the approach to an STI does not end with treating the lesion or discharge.

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Video lesson

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Video pending upload (embedded YouTube)

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Summary

Sexually transmitted infections (STIs) are infections caused by various microorganisms that can be transmitted mainly through vaginal, anal, or oral sexual contact.

They can be caused by:

bacteria;
viruses;
protozoa.

A fundamental concept is that many STIs can be asymptomatic, so the absence of symptoms does not rule out infection or the possibility of transmission.

For the general practitioner

When facing a possible STI we should think of five questions:

What syndrome does the patient present with?
Which microorganisms are most likely?
What samples or tests do I need?
Does it require immediate treatment?
What should I do about sexual partners, prevention, and other STIs?

Key concept

The approach to an STI does not end with treating the lesion or discharge. It includes diagnosis, treatment, prevention, evaluation for other infections, and management of sexual partners when appropriate.

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PDF

⬇ Download lesson summary

Downloadable PDF pending upload.

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Practical algorithm

Urethral discharge + dysuria → think of urethritis → gonococcus/Chlamydia among the main causes.
Painless genital ulcer → consider syphilis.
Painful vesicles or ulcers → consider genital herpes.
Anogenital warts → consider HPV/condylomata.
Epididymal pain in a sexually active patient → consider STIs depending on age and context, but rule out torsion in an acute scrotum.
Diagnosis of an STI → consider testing for other STIs + partner management + prevention.
Recent high-risk HIV exposure → promptly assess the indication for PEP.

An STI is not managed only by treating the patient. The approach includes correct diagnosis, screening for coinfections when appropriate, partner management and prevention of further transmission.

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Clinical case

Content pending upload Progressive clinical case focused on decision-making.

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Self-assessment

Questions pending upload 5–10 multiple-choice questions on this lesson.

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References

Links pending upload References to PubMed, DOI, scientific society guidelines and journals.

Introduction to STIs