**Core Concept**
Brucellosis is a zoonotic infection caused by Brucella species, requiring effective antimicrobial therapy to prevent complications and transmission. The recommended treatment regimen should target the bacteria's intracellular replication and minimize resistance development.

**Why the Correct Answer is Right**
Rifampicin, a rifamycin antibiotic, is a potent inhibitor of RNA synthesis and an essential component of Brucella treatment. Its combination with doxycycline, a tetracycline antibiotic, is recommended due to their synergistic effects against intracellular pathogens. Doxycycline inhibits protein synthesis and enhances the bactericidal activity of rifampicin. This combination allows for effective treatment of Brucella infections, including brucellosis and melioidosis.

**Why Each Wrong Option is Incorrect**
**Option A:** Streptomycin, an aminoglycoside, is not recommended for Brucella treatment due to its poor intracellular penetration and potential toxicity. Doxycycline, when used with streptomycin, is still not the preferred combination for treating Brucellosis.

**Option C:** Ciprofloxacin, a fluoroquinolone, has limited activity against Brucella species, particularly in biofilm-containing environments, making this combination less effective.

**Option D:** Erythromycin, a macrolide antibiotic, is not recommended for Brucella treatment due to its poor efficacy against intracellular pathogens and potential resistance development.

**Clinical Pearl / High-Yield Fact**
For patients with severe Brucella infection, such as those with sepsis or multi-organ involvement, a more aggressive regimen may be required, including the addition of other antibiotics like gentamicin or aminoglycosides. However, the combination of rifampicin and doxycycline remains the cornerstone of treatment.

**✓ Correct Answer: B. Rifampicin with doxycycline**