Viridans streptococci are a common cause of infective endocarditis in South America. Infective endocarditis due to "Streptococcus bovis" occurs more commonly in Europe than in North America. HACEK group of bacteria are also rare causes of infective endocarditis in North America. The viridans group includes "S. oralis", "S. mitis", "S. sanguis", "S. gordonii" and "S. parasanguis". The primary habitats for these organisms are the oral cavity and upper respiratory tract. These bacteria are present in the normal oral flora and enter the bloodstream due to disruption of tissues in the mouth when dental surgical procedures are performed (tooth extractions) or genitourinary manipulation. Similarly, HACEK organisms are a group of bacteria that live on the dental gums, and can be seen with IV drug users who contaminate their needles with saliva. Patients may also have a history of poor dental hygiene, or pre-existing valvular disease. Viridans alpha-hemolytic "streptococci", that are present in the mouth, are the most frequently isolated microorganisms when the infection is acquired in a community setting. In contrast, "Staphylococcus" blood stream infections are frequently acquired in a health care setting where they can enter the blood stream through procedures that cause break in the integrity of skin, such as surgery, catheterization, or during access of long term indwelling catheters or secondary to intravenous injection of recreational drugs. "Enterococcus" can enter the bloodstream as a consequence of abnormalities in the gastrointestinal or genitourinary tracts. Some organisms, when isolated, give valuable clues to the cause, as they tend to be specific. Multiple case reports of infective endocarditis caused by unusual organisms have been published. "Cutibacterium" sp., which are normal skin flora, have been responsible for infective endocarditis sometimes leading to deaths due to the indolent course of this abscess-producing infection."Tropheryma whipplei" has caused endocarditis without gastrointestinal involvement. "Citrobacter koseri" was found in an immunocompetent adult. "Neisseria bacilliformis" was found in a person with a bicuspid aortic valve. Fungal endocarditis (FE) is an often fatal and one of the most serious forms of infective endocarditis.