**Question:** Clinical features of which of the following include conjunctivitis, urethritis, muco-cutaneous lesions and arthritis?

A. Chlamydia
B. Mycoplasma
C. Neisseria
D. Streptococcus

**Core Concept:**
The question is asking about the infectious agents that can present with a combination of conjunctivitis, urethritis, muco-cutaneous lesions, and arthritis. These symptoms are commonly seen in infections caused by certain bacteria and are a result of their invasion into various tissues and organs.

**Why the Correct Answer is Right:**
The correct answer, **D. Streptococcus**, is a group of Gram-positive bacteria that can cause a variety of infections, including those involving multiple body systems. Streptococcal infections are typically characterized by the presence of muco-cutaneous lesions (such as impetigo and scarlet fever), as well as arthritis and urethritis. Streptococcal conjunctivitis is also known as "pink eye" and can result from direct inoculation of the bacteria into the conjunctival sac, leading to inflammation and symptoms.

**Why Each Wrong Option is Incorrect:**

A. Chlamydia (A) is a different group of bacteria that primarily affects the respiratory system and genitourinary tract. Chlamydia-induced conjunctivitis, urethritis, and muco-cutaneous lesions are not typical features of this organism.

B. Mycoplasma (B) is another group of bacteria, but the symptoms mentioned are not typical of a Mycoplasma infection. Mycoplasma infections are usually associated with pneumonia, meningitis, and gastrointestinal symptoms.

C. Neisseria (C) is another group of bacteria, but the symptoms mentioned are not typical of a Neisseria infection. Neisseria-induced urethritis and conjunctivitis are common, but muco-cutaneous lesions and arthritis are not.

**Clinical Pearl:**
Understanding the clinical syndromes associated with various bacterial infections is crucial for a practising physician. These syndromes help in narrowing down the differential diagnosis in patients presenting with symptoms like conjunctivitis, urethritis, muco-cutaneous lesions, and arthritis. By learning the specific features of bacterial infections, clinicians can make accurate diagnoses and initiate appropriate treatments.