Streptococcus anginosus is a species of bacteria and a common part of the body’s normal flora. These microorganisms exist harmlessly in a commensal relationship with their human host. However, these bacteria can cause infections if they spread to normally sterile parts of the body or if a person’s immune system is weakened. This dual nature classifies them as opportunistic pathogens.
The Role of Streptococcus Anginosus in the Body
Streptococcus anginosus bacteria are regular inhabitants of the oral cavity, gastrointestinal tract, and urogenital tract. In these environments, they coexist with the host without causing disease. The transition to a pathogen occurs when the bacteria gain access to sterile sites like the bloodstream, internal organs, or deep tissues. A breach in mucosal barriers from a dental procedure, intestinal disease, or other trauma can provide an entry point. Individuals with compromised immune systems are more susceptible because their bodies cannot control the bacteria if it moves beyond its usual boundaries.
Infections Caused by Streptococcus Anginosus
A defining characteristic of Streptococcus anginosus infections is the bacterium’s strong propensity to form abscesses, which are localized collections of pus. This tendency distinguishes it from many other types of streptococci, and these abscesses can develop in nearly any part of the body. In the head and neck, it can cause dental abscesses and sinusitis. Thoracic infections can lead to lung abscesses and empyema, where pus accumulates in the space between the lungs and chest wall. Within the abdomen, the bacteria are implicated in liver abscesses and intra-abdominal abscesses, often following issues like appendicitis. S. anginosus can also cause serious brain abscesses in the central nervous system and skin abscesses in soft tissues.
Symptoms and Diagnosis
The symptoms of a Streptococcus anginosus infection may begin with general signs of a bacterial illness, such as a persistent fever, chills, and a feeling of unwellness or malaise. As the infection progresses, more specific symptoms develop related to the location of the abscess. For example, a liver abscess might cause localized pain in the upper right abdomen, while a lung abscess could lead to a productive cough and chest pain. A brain abscess can cause intense headaches, neurological changes, or seizures.
Diagnosing an infection involves identifying the bacteria and locating the site of infection. To confirm the presence of S. anginosus, clinicians collect samples of pus from an abscess or blood samples if bacteremia (bacteria in the bloodstream) is suspected. These samples are sent to a laboratory to be cultured, allowing the bacteria to be identified. Medical imaging is used to find and evaluate the abscesses. Technologies like computed tomography (CT) scans, magnetic resonance imaging (MRI), or ultrasounds help determine the precise location, size, and number of abscesses, which is needed for planning treatment.
Treatment Approaches
Treating Streptococcus anginosus infections requires a combined approach of antibiotic therapy and abscess drainage. This dual strategy addresses both the systemic infection and the localized collection of pus. The first component is antibiotic administration, usually given intravenously in a hospital setting to ensure the drug reaches the infection site. Penicillins and other beta-lactam antibiotics are effective, though the choice may depend on susceptibility testing.
However, antibiotics alone are often not enough to resolve the infection. The wall of an abscess can prevent drugs from penetrating to the core. For this reason, drainage of the abscess is an important step. A physician may use a needle to aspirate the pus, or surgical debridement may be required to clean the infected area. Identifying and addressing the original source of the infection, such as a dental problem, is also important to prevent recurrence.