Caron

A caron (/ˈkærən/) or háček (/ˈhɑːtʃɛk/; from Czech háček [ˈɦaːtʃɛk]) or mäkčeň (/ˈmæktʃɛn/; from Slovak mäkčeň [ˈmɛktʃɛɲ] or [ˈmæktʃɛɲ]), also known as a wedge, inverted circumflex, inverted hat, is a diacritic ( ˇ ) placed over certain letters to indicate present or historical palatalization, iotation, or postalveolar pronunciation in the orthography of some Baltic, Slavic, Finnic, Samic, Berber and other languages. The caron also indicates the third tone (falling and then rising) in the Pinyin romanization of Mandarin Chinese.

It looks similar to a breve, but has a sharp tip, like an inverted circumflex (ˆ), while a breve is rounded. Compare the caron: Ǎ ǎ Ě ě Ǐ ǐ Ǒ ǒ Ǔ ǔ to the breve: Ă ă Ĕ ĕ Ĭ ĭ Ŏ ŏ Ŭ ŭ.

The left (downward) stroke is usually thicker than the right (upward) stroke in serif typefaces.

The caron is also used as a symbol or modifier in mathematics.

Names

Different disciplines generally call this diacritic by different names. Typography tends to use the term caron. Linguistics more often uses haček (with no long mark), largely due to the influence of the Prague School (particularly on Structuralist linguists who subsequently developed alphabets for previously unwritten languages of the Americas). Pullum's and Ladusaw's Phonetic Symbol Guide (Chicago, 1996) uses the term wedge.

HACEK endocarditis

The HACEK organisms are a group of fastidious Gram-negative bacteria that are an unusual cause of infective endocarditis (IE), which is an inflammation of the heart due to bacterial infection. HACEK is an abbreviation of the initials of the genera of this group of bacteria: Haemophilus, Aggregatibacter (previously Actinobacillus), Cardiobacterium, Eikenella corrodens, Kingella. The HACEK organisms are a normal part of the human microbiota, living in the oral-pharyngeal region.

The bacteria were originally grouped because they were thought to be a significant cause of infective endocarditis, but recent literature has shown that they are rare and only responsible for 1.4–3% of all cases of this disease.

Organisms

HACEK originally referred to Haemophilus parainfluenzae, Haemophilus aphrophilus, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella kingae. However, taxonomic rearrangements have changed the A to Aggregatibacter species and the H to Haemophilus species to reflect the recategorization and novel identification of many of the species in these genera. Some reviews of medical literature on HACEK organisms use the older classification, but recent papers are using the new classification.