All of the following are types of potentially harmful organisms which may cause infectious disease EXCEPT?

Lactobacillus is a type of bacteria that is generally regarded as beneficial rather than harmful. It plays a crucial role in human health, particularly in digestive health and maintaining a healthy balance of gut flora. This type of bacteria is commonly found in fermented foods such as yogurt and is known for its probiotic properties, which can help prevent infections by outcompeting harmful microorganisms.

On the other hand, fungi, bacteria (including harmful species), and parasites are known to cause infectious diseases in humans. They can disrupt normal bodily functions and lead to various health issues. Understanding the role of different microorganisms helps in identifying which ones can lead to infections and which contribute positively to health.