Streptococcus agalactiae is a Gram positive bacterium of the genus streptococcus that occurs in pairs or short chains. It is one of many common bacteria naturally occurring in the human gastrointestinal tract; however it can spread to other sites throughout the body and cause infection. More specifically, Streptococcus agalactiae has been known to spread to the vagina in women, which is clinically significant because of the possible damage to newborns during child birth.
Streptococcus agalactiae is the most common cause of septicemia in newborn children. Septicemia is a condition describing the presence of pathogenic microorganisms in the blood, which then leads to sepsis, more commonly called blood poisoning. If not treated, this disease quickly leads to severe inflammation, organ failure, and death. Because newborns lack the immune systems defenses required to protect against many infections, Streptococcus agalactiae can be particularly devastating. Infection in newborns from this bacterium is generally accompanied by pneumonia or meningitis; however symptoms of these diseases are often less specific than they are in adults, and it can therefore be more difficult to diagnose the cause.
Streptococcus agalactiae is also known to cause infection in other species of mammals. One of the most significant examples is infection in cattle because of the complications caused for the dairy and beef industries. Bacterial contamination in cattle causes mastitis, an udder infection leading to lower milk production and eventually death. Spread of the disease can be rampant amongst herds, which has caused some countries to pass codes enforcing Streptococcus agalactiae control. Usually spreading of the infection can be traced back to contaminated milking machines. In total, mastitis causes the US dairy industry an average of 1.8 billion dollars annually.
More recently, wildlife officials in Australia have come across deceased grouper washing up on beaches. The fish have shown to have been infected with Streptococcus agalactiae. Outbreaks have been reported in other locations across the globe as well, in some cases causing economic hits to the fishing industry. Infections caused by the bacterium have also been found in crocodiles, camels, cats, and even dolphins.