Streptococcal bacteria are a group of microscopic organisms often found in chains, resembling a string of beads. While many people are familiar with “strep throat,” caused by Group A Streptococcus, this term encompasses a much broader family of bacteria. These diverse types of streptococci can inhabit various parts of the body and do not all cause the same types of illness. Understanding these differences is key when considering if and how an infection should be treated.
Understanding Streptococcal Bacteria
Streptococci are gram-positive bacteria characterized by their spherical shape and tendency to form chains. This diverse genus includes species that can cause disease in humans and animals. The classification of streptococci into groups, such as Group A, B, C, and G, is often based on specific carbohydrates found on their cell walls.
Group A Streptococcus (GAS), scientifically known as Streptococcus pyogenes, is widely recognized as the cause of “strep throat” and is typically treated with antibiotics to prevent complications like rheumatic fever. In contrast, “non-Group A Strep” refers to all other streptococcal species that do not possess the Group A carbohydrate antigen. This category is extensive and includes various distinct bacteria like Group B Strep (Streptococcus agalactiae), Viridans Group Strep, and Streptococcus pneumoniae. These non-Group A types differ significantly in their characteristics, preferred habitats within the body, and the kinds of infections they can cause.
Common Non-Group A Streptococcal Infections
Non-Group A streptococci are responsible for a range of infections, varying in severity and affected body parts. Group B Strep (Streptococcus agalactiae) is known for causing serious infections in newborns, including sepsis (blood poisoning), pneumonia, and meningitis. Pregnant individuals are often screened for Group B Strep colonization, as antibiotics given during labor can help prevent transmission to the baby. Adults, particularly those over 65 or with underlying health conditions, can also develop Group B Strep infections, which may manifest as urinary tract infections, skin infections, or pneumonia.
Another important category is the Viridans Group Strep, a diverse collection of species that are typically part of the normal oral flora. These bacteria can enter the bloodstream, especially after dental procedures, and cause infective endocarditis, a serious infection of the heart valves. Streptococcus pneumoniae, also known as pneumococcus, is a distinct non-Group A Strep species that causes a variety of common infections. It is a leading cause of bacterial pneumonia, ear infections (otitis media), and meningitis, affecting both children and adults. Group C and G streptococci are less common causes of human disease but can cause infections similar to those seen with Group A Strep.
When Treatment is Recommended for Non-Group A Strep
Treatment for non-Group A strep infections is recommended when the bacteria are causing noticeable symptoms, leading to severe illness, or invading parts of the body that are normally sterile. For instance, if Streptococcus pneumoniae causes pneumonia, meningitis, or bloodstream infections, antibiotic therapy is necessary. Similarly, invasive Group B Strep infections in newborns, manifesting as sepsis or meningitis, require prompt antibiotic treatment.
Treatment is also crucial for specific patient populations who are more vulnerable to complications. This includes immunocompromised individuals, those with underlying heart conditions susceptible to endocarditis from Viridans Group Strep, or pregnant individuals colonized with Group B Strep who receive antibiotics during labor to protect the newborn. The location of the infection plays a significant role; for example, Viridans Group Strep causing endocarditis requires treatment. Preventing serious complications, such as heart valve damage from endocarditis or severe neurological issues from meningitis, guides the decision to treat. Diagnosis often involves culturing the bacteria and performing sensitivity testing to determine which antibiotics will be most effective.
When Treatment May Not Be Necessary
Many non-Group A strep species are natural inhabitants of the human body and do not always cause disease. For example, Viridans Group Strep commonly resides in the mouth and gastrointestinal tract as part of the normal microbiome. In these instances, their presence is considered colonization rather than an active infection, and antibiotic treatment is not needed.
Asymptomatic carriage is another scenario where treatment is not recommended. An individual might test positive for a non-Group A strep, such as Group B Strep, but show no signs or symptoms of illness. Unless a pregnant individual is colonized with Group B Strep, which warrants treatment during labor to prevent neonatal transmission, asymptomatic carriage in other adults does not require antibiotics. Some minor, localized infections caused by these bacteria might also resolve on their own without the need for medication. Unlike Group A Strep, which is always treated to prevent serious post-infection complications like rheumatic fever, the mere presence of most non-Group A strep does not necessitate intervention.