<unk> s are most commonly caused by an overgrowth of bacteria that normally populate the oral cavity. In a healthy adult, billions of bacteria, viruses, and fungi reside within the oral cavity and represent more than 500 different species. They are collectively known as the oral microbiome. When healthy, the oral microbiome is in dynamic equilibrium such that no one bacteria or group of organisms dominates. However, certain situations, like a decaying tooth root or a penetrating puncture wound from a fish bone, can generate an environment that disrupts the normal oral microbiome and promote the growth of pathogenic bacteria. Although sore throats (pharyngitis) are caused by viruses and oral yeast infections (candidiasis) are caused by fungi, most<unk> s that lead to swelling and abscesses are caused by bacteria. The bacteria of the oral microbiome consist of a wide variety of gram positive cocci and rods, gram negative cocci and rods, obligate anaerobes, and facultative anaerobes. The most common bacteria that causes<unk> s are Streptococcus species. Poor dental hygiene promotes the accumulation of these bacteria at the tooth root, eventually causing a cavity or dental caries. The decaying tooth root provides bacteria with an enclosed environment with low oxygen content. Consequently, the obligate and facultative anaerobes present within the oral cavity flourish and outcompete the other bacteria at the site of tooth decay, causing the dental caries to escalate into a<unk> . The corrosive enzymes released by the anaerobes erode the surrounding bone and enable the infection to invade surrounding structures. Given the natural history of a<unk> , the vast majority of clinically-treated oral infections are polymicrobial, or caused by multiple different species of bacteria at the same time. Until the source of the infection is controlled with some form of drainage and antibiotics, a<unk>  will likely not resolve on its own.
Mouth infection
Dental plaque
Skin and skin structure infection
Pain in babies
Respiratory tract infection
Lower respiratory tract infection
Animal bite
Dental aerosol