What type of bacteria can exist in pairs and cause pneumonia?

Diplococci are a type of bacteria that exist in pairs and are known to be pathogenic, meaning they can cause disease in humans. Specifically, diplococci can lead to a variety of infections, including pneumonia. This is due to their unique structure, where two cocci (spherical bacteria) are joined together, which can facilitate their ability to adhere to host tissues and evade the immune system.

In contrast, spirilla are spiral-shaped bacteria, staphylococci cluster in grape-like structures, and bacilli are rod-shaped bacteria. While these other forms of bacteria can cause various infections, they do not specifically exist in pairs or are primarily associated with causing pneumonia in the way that diplococci are. This characteristic of diplococci allows them to be linked with specific respiratory infections, making them significant in the study of pathogenic bacteria and the diseases they cause.