**Core Concept**
Acute infectious purpura fulminans is a rare and life-threatening condition characterized by the rapid onset of widespread purpura, necrosis, and hemorrhage. It is primarily caused by a severe infection that leads to the activation of the coagulation cascade, resulting in disseminated intravascular coagulation (DIC).

**Why the Correct Answer is Right**
The correct answer involves two pathogens: Neisseria meningitidis and varicella-zoster virus. Neisseria meningitidis is a gram-negative bacterium that can cause meningococcemia, a severe infection that can lead to purpura fulminans. Varicella-zoster virus, the causative agent of chickenpox and shingles, can also trigger purpura fulminans, particularly in immunocompromised individuals. The pathogenesis involves the activation of the coagulation cascade by the bacterial or viral products, leading to the formation of thrombi and subsequent purpura.

**Why Each Wrong Option is Incorrect**
**Option B:** Gonococi are gram-negative bacteria that can cause gonorrhea, but they are not typically associated with purpura fulminans. Gonococcal infections can cause disseminated gonococcal infection, which presents with a different set of symptoms, including skin lesions, arthritis, and tenosynovitis.

**Option C:** E. coli is a gram-negative bacterium that can cause a range of infections, including urinary tract infections, sepsis, and meningitis. However, it is not commonly associated with purpura fulminans.

**Option D:** Proteus is a gram-negative bacterium that can cause urinary tract infections and septicemia. Like E. coli, it is not typically associated with purpura fulminans.

**Clinical Pearl / High-Yield Fact**
Purpura fulminans is a medical emergency that requires prompt recognition and treatment. Early diagnosis and initiation of supportive care, including fluid resuscitation and anticoagulation, can improve outcomes.

**✓ Correct Answer: A. Neisseria meningitidis and varicella**