There can be no bacterial infection without the presence of which type of bacteria?

• A. pathogenic bacteria
• B. nonpathogenic bacteria
• C. viruses
• D. fungi

Answer: (A)

The main idea is that an infection occurs when disease-causing organisms are present, and for a bacterial infection, those organisms must be pathogenic bacteria. Nonpathogenic bacteria can exist harmlessly as part of the normal flora and don’t cause illness by themselves. Viruses and fungi are different types of microbes and are not bacteria, so they aren’t the agents of a bacterial infection. So, the presence of pathogenic bacteria is what defines a bacterial infection.