Anaerobic and microaerophilic cocci and gram-negative and gram-positive anaerobic bacilli are the predominate bacterial isolates. Like other cocci, streptococci are round bacteria. Anaerboci gram-positive cocci and micraerophilic streptococci are often recovered in these infections. They sometimes form filaments, which fragment into bacilli or cocci once disturbed. It is most active against gram-positive cocci, and has moderate activity against some gram-negative bacilli. Anaerobic gram-positive cocci are frequently isolated from anaerobically infected bones and joints. A phyogenic non-motile Gram-positive cocci which forms into grape like clusters. These bacteria are Gram-positive, anaerobic, indole-negative cocci. When anaerobic and facultative cocci were recovered most of the infection were polymicrobial. They have round cells, called cocci (singular coccus), or rod-like forms (bacillus). They are gram-positive, catalase-negative, non-motile cocci that are found singly, in pairs, or in chains. "Neisseria" species are fastidious, Gram-negative cocci that require nutrient supplementation to grow in laboratory cultures. They therefore cannot be classified as rods, cocci or spirochetes. These bacteria are extracellular, and made up of non-motile and non-sporing cocci. Peptoniphilus are gram positive anaerobic cocci that were formerly classified in the genus Peptostreptococcus.