S porcinus was associated in the USA with a contagious clinical entity in growing pigs known as streptococcal lymphadenitis, jowl abscesses, or cervical abscesses. The importance of this disease has declined considerably, and it is not recognized as an important economic entity in other countries. Transmission is possible by contact or ingestion of food or water contaminated by purulent material from abscesses or feces harboring the organism. Organisms infect the pig through the mucosa of the pharyngeal or tonsillar surfaces and are carried to the lymph nodes, primarily of the head and neck region, where abscesses are formed. Abscesses may be observed at slaughter, and enlargement of lymph nodes in the throat region may be evident. S porcinus is also occasionally found in the vaginal mucus of sows and the semen and prepuce of boars. It is generally considered to be a secondary invader.
S porcinus is sensitive to penicillins, and antibiotic therapy will usually resolve acute infections if detected. However, antibiotic treatment is not usually successful in treating swine with established abscesses or in eliminating carriers. Resistance to tetracycline has been reported, but pulsing tetracyclines in the feed at the therapeutic level of 400 g/ton is commonly used in an attempt to control this condition. Vaccination (autogenous) is possible but has not been widely used because cervical abscesses are not a widespread problem.
There is no evidence that S porcinus has zoonotic potential, but it has been implicated in genitourinary infections and pregnancy complications in women.
Last full review/revision March 2012 by Darryl Ragland, DVM, PhD