Before the widespread use of antibiotics, the main causative agents of the disease were pneumococci and streptococci, but with the widespread use of antibiotics, the number of pustules caused by these agents has gradually decreased, while those caused by staphylococci have become more and more common and are the most common causative agents at present. Other pathogenic bacteria include Pseudomonas aeruginosa, Escherichia coli, Salmonella and other gram-negative rods.