Veillonella parvula is a species of bacteria classified in the Acidaminococcaceae. The species normally lives as a commensal in the human oral flora and intestine. The species can become an opportunistic pathogen, especially in the presence of immunodeficiency.
What is Veillonella parvula?
Veillonella are named after the French bacteriologist Adrien Veillon. It is a genus of the Acidaminococcaceae, also formerly known as Veillonellaceae. The bacterial genus is a part of the physiological oral flora and causes dental caries under certain circumstances. Veillonella are also found in the intestinal flora and the vaginal flora. Bacteria of the genus continue to live in the rumen of ruminants, where they facilitate the conversion of lactic acid to acetate and propionate in a rumen symbiosis. All species of the genus are obligate anaerobic bacteria with gram-negative staining behavior, occurring in the form of cocci. They are known for their fermentation ability of lactate. Veillonella parvula are a species of the genus Veillonella that is associated as a human pathogen under certain conditions and thus can be called an opportunistic pathogen. Bacteria of the species have been isolated, for example, from patients with endocarditis, periodontitis, meningitis, or osteomyelitis. Some cases of sepsis have also been reported in association with the bacterial species. Bacterial strains of the species do not possess active locomotion and occur primarily in chain arrangements. Their size is about 0.4 micrometers. The strains of the species bear an outer shell of lipopolysaccharides, which is interpreted as a virulence factor of the bacterial species.
Occurrence, distribution, and characteristics
The species Veillonella parvula does not form spores and occurs as a commensal in the human intestine as well as in the plaque of the oral flora. The bacterial species cannot live without putrescine and cadaverine, which are important components of the species’ own peptidoglycan. Plasmalogens and ether phospholipids also make up the species, helping to regulate membrane fluidity. Bacteria of the species Veillonella parvula, unlike other bacteria, do not metabolize carbohydrates but use organic acids such as lactate for energy. Since bacteria of this species cannot ferment carbohydrates, the conversion of lactate to vinyl propionate and vinyl acetate is their main source of energy production. The bacteria do not possess hexokinase, but do have the enzyme methylmalonyl-CoA decarboxylase. This allows the bacteria to metabolize succinate in the presence of lactate. They use the resulting free energy to power their sodium ion pumps. The organisms live strictly anaerobic. Thus, they do not need elemental oxygen to survive and grow, but are actually inhibited in their growth by the presence of oxygen. They often live in a mutual beneficial relationship with other microorganisms, for example with the bacteria of the natural oral flora. The metabolic processes of the various oral bacteria are precisely coordinated, so that the presence of one species favors the presence of another. In many cases, human pathogenic bacteria exploit the presence of Veillonella parvula for their own benefit, thus using the species as their personal virulence factor. In principle, the bacterial species Veillonella parvula is considered a commensal that neither harms nor directly benefits the human organism. However, because strains of the bacterium have also been isolated from patients with infections such as endocarditis, periodontitis, meningitis, and osteimyelitis, there is sometimes talk of opportunistic pathogens that can exploit a weakening of the immune system for their own benefit and thus promote infections under certain circumstances.
Diseases and ailments
In meningitis, the pia mater and arachnoid mater in the area of the brain become inflamed. This phenomenon can be caused by bacteria such as the species Veillonella parvula. Bacterial meningitis is divided into a purulent and a non-purulent form and causes symptoms such as general signs of infection with fever, fatigue and headache. These symptoms are associated with nausea, vomiting, back pain, stiff neck and opisthotonus. In addition, disorders of consciousness often present, which may be accompanied by disorientation or loss of reality and apathy, and even coma.Cramps, photophobia and skin changes are also typical symptoms of the potentially life-threatening disease. Osteomyelitis associated with the bacterial genus is also an acute or chronic inflammation, but in this case it affects the bone and often spreads secondarily to the bone marrow. Osteomyelitis often occurs after surgery and is then usually caused by hospital germs. Osteomyelitis caused by the pathogen Veillonella parvula is an endogenous infection, since the bacteria of this species originate from the patient’s own body. In periodontitis, the bacterial species causes inflammation of the periodontium. Often, the primary focus of infection in osteomyelitis or meningitis caused by the pathogen Veillonella parvula corresponds to a focus of infection in the oral region, from which the bacteria spread to the target organs. In addition to the bone and brain, the heart can also be affected by the infection, such as in endocarditis or endocarditis. In rare cases, sepsis (blood poisoning) has been reported following infection with Veillonella parvula. In sepsis, the bacteria are present in the blood and cause a systemic inflammatory response of the entire organism. Immune-healthy patients are less susceptible to such sepsis because their immune system destroys bacteria in the blood within a very short time so that they do not spread further. Illness, old age, and drug therapies with cytostatics, for example, can weaken the immune system and thus promote sepsis.