What are epididymitis, orchitis and epididymo-orchitis?

Infection: These are infections of the structures within the scrotum, the testis (orchitis), the tubular structure adjacent to the testis (epididymitis), or both (epididymo-orchitis). In young men these infections are often sexually transmitted, like chlamydia. Older men usually are infected with gram negative bacteria that may also cause urinary tract infections.

EPIDIDYMITIS: Infections of the testis, epididymis and both. They can be bacterial, viral or simply sterile inflammation. They can be acute or chronic.