Which of the following types of bacteria is considered harmless?

Non-pathogenic bacteria are those types that do not cause disease in humans and can actually be beneficial to our health. They are often part of the normal flora of various parts of the body, such as the skin and gut, and play essential roles in processes like digestion and protecting against harmful pathogens. For instance, certain non-pathogenic bacteria can help in nutrient absorption and produce vitamins that our bodies need.

In contrast, pathogenic bacteria are known to cause infections and diseases, and they can lead to various health issues. The terms rod-shaped and spherical refer to the physical shapes of bacteria but do not inherently indicate whether they are harmful or harmless. Thus, while the shape can describe certain types of bacteria, it is their pathogenicity or non-pathogenicity that determines their impact on health. Knowing the difference is vital for understanding how to maintain proper hygiene and safety in environments such as salons, where the risk of infection can be a concern.