Veillonella atypica is a type of bacterium that exists widely in the human body. This organism is classified as an anaerobic, Gram-negative coccus, meaning it is round-shaped, lacks a specific cell wall structure identified by Gram staining, and grows only in environments without oxygen. Unlike many other bacteria, Veillonella atypica cannot use carbohydrates or amino acids as its energy source. Instead, it uniquely ferments lactic acid to sustain itself.
Where Veillonella Atypica Resides
Veillonella atypica commonly resides as a natural inhabitant within various human body sites, forming part of the normal flora. It is frequently found in the oral cavity, gastrointestinal tract, and urogenital tract, contributing to the healthy microbial community.
In the oral cavity, it is abundant in saliva and acts as an early colonizer, contributing to dental plaque formation by coaggregating with other oral bacteria. Research indicates that Veillonella atypica prefers sites like the tongue dorsum, tonsils, and throat, rather than dental plaque or keratinized gum tissues.
Its Role in Health and Disease
The presence of Veillonella atypica within the human microbiome reveals a dual nature, acting both as a beneficial partner and, under certain circumstances, as an opportunistic threat. As a commensal bacterium, it engages in metabolic cooperation with other microbes, particularly Streptococcus species, which produce lactic acid. Veillonella atypica consumes this lactic acid, converting it into weaker organic acids like propionate, acetate, and formate. This helps maintain a balanced environment by reducing acidic conditions that can contribute to tooth demineralization and dental caries.
Beyond oral health, Veillonella atypica is linked to athletic performance. Studies observe an increased abundance of Veillonella species, including V. atypica, in endurance athletes following intense exercise, indicating a beneficial association. The bacterium’s ability to metabolize exercise-induced lactate into propionate, a short-chain fatty acid, may enhance exercise capacity and improve measures like VO2 max. This metabolic conversion may also influence energy expenditure and fat oxidation within the host.
In the gut, Veillonella atypica is associated with positive metabolic outcomes, including increased insulin sensitivity and lower post-meal insulin levels. This bacterium also participates in the formation of complex microbial communities known as biofilms, sometimes alongside Streptococcus species. These biofilms offer protection against environmental stressors or facilitate nutrient exchange between different bacterial species.
Despite its generally benign presence, Veillonella atypica can become an opportunistic pathogen, particularly when an individual’s immune system is weakened. While rare, it has been implicated in various infections, often as part of a polymicrobial infection. It has been documented in severe infections like bacteremia, endocarditis, osteomyelitis, retropharyngeal abscess, and pneumonia, though V. atypica is less frequently reported as a sole cause compared to other Veillonella species. Its increased abundance is also correlated with the severity of certain liver conditions, such as alcoholic hepatitis and cirrhosis.
Diagnosing and Managing Related Conditions
Identifying Veillonella atypica when it causes infection can present challenges, as conventional laboratory methods based on physical characteristics may not always provide clear distinctions between species. More precise diagnostic approaches involve molecular techniques, such as Polymerase Chain Reaction (PCR) for 16S rRNA gene sequencing, or Matrix-Assisted Laser Desorption/Ionization-Time of Flight (MALDI-TOF) mass spectrometry. These advanced methods offer improved accuracy in differentiating Veillonella atypica from other closely related bacteria. Culturing this bacterium requires strictly anaerobic conditions and can take several days to yield results.
Managing conditions linked to Veillonella atypica infections primarily involves antibiotic therapy, though specific treatment guidelines are not extensively established due to the rarity of severe cases caused solely by this organism. Treatment decisions are tailored by medical professionals based on the infection’s location, severity, and the patient’s overall health.
Antibiotics generally effective against anaerobic bacteria are considered, including penicillin, cephalosporins, ceftriaxone, clindamycin, and metronidazole. However, some V. atypica strains have shown high resistance to penicillin and moderate resistance to metronidazole. Amoxicillin/clavulanic acid and ceftriaxone demonstrate greater effectiveness, with lower resistance rates for V. atypica.
The duration of antibiotic treatment varies, from 7 to 15 days for bloodstream infections, or longer for localized infections. Supportive care, such as managing symptoms and maintaining patient stability, accompanies antibiotic regimens.