Fungal spores may be viewed directly on hair shafts. This technique identifies a fungal infection in about 40%–70% of the infections, but cannot identify the species of dermatophyte. Culture test: This is the most effective, but also the most time-consuming, way to determine if ringworm is on a pet. In this test, the veterinarian collects hairs from the pet, or else collects fungal spores from the pets hair with a toothbrush, or other instrument, and inoculates fungal media for culture. These cultures can be brushed with transparent tape and then read by the veterinarian using a microscope, or can be sent to a pathological lab. The three common types of fungi which commonly cause pet ringworm can be identified by their characteristic spores. These are different-appearing macroconidia in the two common species of Microspora, and typical microconidia in Trichophyton infections.Identifying the species of fungi involved in pet infections can be helpful in controlling the source of infection. M. canis, despite its name, occurs more commonly in domestic cats, and 98% of cat infections are with this organism. It can also infect dogs and humans, however. T. mentagrophytes has a major reservoir in rodents, but can also infect pet rabbits, dogs, and horses. M. gypseum is a soil organism and is often contracted from gardens and other such places. Besides humans, it may infect rodents, dogs, cats, horses, cattle, and swine.
Therefore, more common skin conditions, like cellulitis, foreign body reaction, skin cancer, and fungal or parasitic infections, are often explored first. Overall, diagnosis and treatment of this rare skin infection is often delayed because of a lack of suspicion.Lab tests for finding M. marinum include cultures where a swab or sample is taken and grown in the laboratory. Cultures of M. marinum are fairly difficult to grow, and results may take several weeks. The culture may be negative, even if there is an active infection. Treatment may still be considered even if the test results are negative, especially if the patients history supports past fish or fish-tank exposure. In the absence of positive culture results, a skin or tissue biopsy may be a helpful test to render a microscopic diagnosis. Another technique that can be used to detect the bacteria is Polymerase Chain Reaction (PCR). A biopsy sample itself is sufficient to detect the exact type of bacteria by means of PCR. Prevention
Avoid fresh or saltwater activities if there are open cuts, scrapes, or sores on the skin, especially in water where this bacterium is known to exist. Wear heavy gloves (leather or heavy cotton) while cleaning or processing fish, especially fish with sharp spines that may cause cuts to the hands and skin. Wash hands thoroughly with soap and water after fish processing or use a waterless cleanser. Wear waterproof gloves while cleaning home aquariums or fish tanks.