Non-pathogenic bacteria are characterized as being:

Non-pathogenic bacteria are characterized as being beneficial and harmless to humans. These types of bacteria play crucial roles in various processes, such as digestion and maintaining a balanced microbiome in the body. They can outcompete harmful bacteria for resources, thus helping to protect against infections. Non-pathogenic bacteria are an essential part of many ecosystems and contribute to beneficial processes in both environmental and human health contexts, such as nitrogen fixation in soil and production of vitamins in the human gut.

In the context of the question, the other options describe characteristics of pathogenic bacteria that are capable of causing disease or harm, which is fundamentally different from the nature of non-pathogenic bacteria. Non-pathogenic bacteria do not exhibit infectious characteristics nor do they act as causative agents for diseases, highlighting their essential role as safe microorganisms in our environment and within our bodies.