Pathogenic bacteria are bacteria that can cause disease in humans, animals, and plants. There are many different types of pathogenic bacteria, classified by their shape, size, and the type of infection they cause. Generally, pathogenic bacteria can be divided into two main categories: Gram-positive and Gram-negative.
Gram-positive bacteria are characterized by their thick cell walls, which contain a high amount of peptidoglycan. These bacteria are generally harmless, but some are capable of causing diseases such as streptococcal infections, staphylococcal infections, and food poisoning.
Gram-negative bacteria are characterized by their thin cell walls which contain a low amount of peptidoglycan. These bacteria are often more infectious and dangerous than Gram-positive bacteria, and are responsible for causing diseases such as salmonella, E. coli, and cholera.
In conclusion, there are two main strains of pathogenic bacteria: Gram-positive and Gram-negative. Each strain has different characteristics, and is capable of causing different types of diseases. It is important to understand the differences between the two in order to prevent and treat infections.