Anaerobic Cocci

The anaerobic cocci are major components of the normal microbiota of the mouth, upper respiratory tract, gastrointestinal tract, vagina, and skin. Gram-positive cocci and gram-negative cocci ( Veillonella spp.) are the anaerobic bacteria most commonly isolated from clinical specimens. Traditional methods of isolating anaerobes is time consuming and can require multiple subcultures and biochemical analyses; the use of inappropriate culture and transport methods further reduces the ability to isolate anaerobic cocci. Newer techniques such as polymerase chain reaction 16S (small subunit) ribosomal RNA sequencing and matrix-assisted laser desorption/ionization–time of flight (MALDI-TOF) mass spectrometry more rapidly and sensitively identify anaerobes from clinical specimens, ^{, ,} and these techniques have added to our understanding of the role of these anaerobes in human infections.

Compared with all gram-positive anaerobes, the gram-positive cocci are most prominent, accounting for approximately ≥25% of all anaerobes grown from clinical specimens. Gram-positive anaerobic cocci are most often a part of the following infections: deep soft tissue, central nervous system, intra-abdominal, bone and joint, and gynecologic. Although anaerobic bloodstream infection (BSI) is rare in children, anaerobic cocci have been isolated, especially in cases of polymicrobial BSI. The classification of anaerobic gram-positive cocci is changing continually as new species are added or reclassified. At present, 6 clinically significant genera of anaerobic gram-positive cocci are recognized: Peptostreptococcus , Finegoldia , Parvimonas , Anaerococcus , Petoniphilus , and Peptococcus . The first 5 genera are most often associated with infection. Finegoldia magna is more often isolated in pure culture from clinical infection sites. ^, Related anaerobic gram-positive cocci include Gallicola , Murdochiella Atopobium , and Anaerosphera . The genera Sarcina , Coprococus , and Blautia are phylogenetically more distantly related gram-positive anaerobic cocci. Of the 3 genera of anaerobic gram-negative cocci, only 1, V eillonella , is found in clinical isolates. Veillonella parvula is a commensal in the oral, gastrointestinal, respiratory, and female genital tract biota, and it is the species most commonly isolated from human specimens. In a 20-year review documenting anaerobes isolated from children with clinical infections, Veillonella spp. were recovered most often from abscesses, aspiration pneumonias, burns, bites, and sinuses. Most often a part of a polymicrobial infection, Veillonella was isolated alone in 5% of these children. Veillonella parvula causes serious infection occasionally in association with malignant disease, corticosteroid use, previous surgical procedures, indwelling devices, or intravenous drug use and rarely in otherwise healthy people. ^,