Acute or chronic onychomycosis is more common. Nail fungitis usually occurs after a break in the nail plate and adjacent skin folds, and the common pathogens are bacterial or fungal. However, non-infectious factors such as chemical irritation, excessive humidity, systemic diseases, and medications may contribute to the development of nail fungus. Acute infections causing abscesses may resolve on their own, while severe cases require local incision and decompression and drainage plus antibiotic treatment. Etiology and risk factors for acute perineal nail infection Most acute nail infections occur as a result of minor trauma to the nail bed, such as flesh pricks, nail trimming, finger sucking, dishwashing, and residual or non-residual foreign bodies from needle stick injuries. These minor traumas can disrupt the normal skin barrier around the nail and lead to bacterial colonization of the perineal skin. In a study of 61 patients with perineal nail infections, it was found that about 25% of perineal infections were caused by anaerobic bacteria, 25% of perineal infections were caused by aerobic bacteria, and the remaining 50% of patients had mixed bacteria. The most common aerobic bacteria in acute perineal nail infections are Staphylococcus, γ-hemolytic streptococci, Aikenia, Klebsiella, and group A β-hemolytic streptococci; the most common anaerobic bacteria include Bacteroidetes, Gram-positive anaerobic cocci, and Clostridium; other bacteria such as Enterococcus, Aspergillus, and Pseudomonas aeruginosa can also cause perineal nail infections. In addition, non-bacterial pathogens such as yeast, viruses, and other conditional pathogens can also cause an attack of nail infection. Not all patients have a significant history of trauma during an acute nail infection attack. Acute onychomycosis is characterized by localized pain, redness of the skin, inflammatory reaction, and swelling of the skin around the nail, usually limited to a single segment. The onset of symptoms varies, usually occurring within 2-5 days after trauma. Fluctuations of the perinail skin abscess may not be observed early in the onset of symptoms. In the late symptomatic stage, the perineal skin abscess fluctuations may spread under the nail and involve the contralateral epineal and perineal skin. Abscess formation can be seen under the nail plate, pushing the nail plate away from the nail bed matrix; at this point it can be called a perineal infection.