What best describes the morphology and growth requirements of Helicobacter species?

What best describes the morphology and growth requirements of Helicobacter species?

• A. Gram-positive cocci
• B. Gram-negative helical or S-shaped rods, microaerophilic
• C. Gram-negative rods, obligate aerobe
• D. Gram-positive bacilli, strict anaerobe

Answer: (B)

Helicobacter species are Gram-negative, curved or helical (S-shaped) rods that are motile with multiple flagella and require a microaerophilic environment to grow. This means they need reduced oxygen levels—less than atmospheric air—for optimal growth, often with increased CO2. This combination of cell wall type (Gram-negative), distinctive curved/spiral shape, and growth under low-oxygen conditions best matches their biology. They are not Gram-positive cocci, nor are they Gram-negative rods that grow only in full aerobic conditions, and they are not Gram-positive bacilli that are strictly anaerobic, so those descriptions don’t fit.

Helicobacter species are Gram-negative, curved or helical (S-shaped) rods that are motile with multiple flagella and require a microaerophilic environment to grow. This means they need reduced oxygen levels—less than atmospheric air—for optimal growth, often with increased CO2. This combination of cell wall type (Gram-negative), distinctive curved/spiral shape, and growth under low-oxygen conditions best matches their biology. They are not Gram-positive cocci, nor are they Gram-negative rods that grow only in full aerobic conditions, and they are not Gram-positive bacilli that are strictly anaerobic, so those descriptions don’t fit.