Where are HACEK organisms found?

The HACEK organisms are a normal part of the human microbiota, living in the oral-pharyngeal region.

What is hacek group?

The HACEK group of bacteria (Haemophilus species, Aggregatibacter species, Cardiobacterium hominis, Eikenella corrodens, and Kingella species) are a small, heterogeneous group of fastidious, gram-negative bacteria that frequently colonize the oropharynx and have long been recognised as a cause of infective endocarditis …

Can Haemophilus grow on blood agar?

Haemophilus influenzae requires both factors X and V; accordingly, it grows on chocolate agar but not on blood agar (Fig. 30-2), although it may appear on a blood agar plate as tiny satellite colonies around the colonies of other bacteria that have lysed red blood cells.

Is Actinobacillus Gram positive or negative?

The organisms of the genus Actinobacillus are small, gram-negative, nonmotile, nonsporing bacilli, and coccobacilli. They are often interspersed with coccal elements. They are aerobic, microaerophilic, or facultatively anaerobic, fermenting carbohydrates with the production of acid but no gas.

Why does Haemophilus grow on blood agar?

Haemophilus species are Gram-negative coccobacilli similar in ultrastructural features to other pathogenic bacilli. Haemophilus influenzae requires hemin (factor X) and NAD+ (factor V) for growth. Other Haemophilus species require only NAD+ and therefore grow on blood agar.

How are HACEK microorganisms used in blood culture?

HACEK microorganisms grow slowly in standard blood culture media, and recovery may require prolonged incubation. HACEK organisms are typically oropharyngeal commensals and have long been recognized as a cause of infective endocarditis (IE). [ 2]

How long does it take to detect HACEK in blood culture?

This was attributed to slow growth in old formulations of blood culture bottles and resulted in recommendations for extended incubation (>5 days) when the presence of these organisms was suspected. However, modern blood culture instruments reliably detect HACEK organisms within a 5-day incubation period.

What does HACEK stand for in microbiology?

The acronym “HACEK” is common in clinical microbiology, although its pronunciation may be somewhat controversial (hay-sek or hah-sek?). The acronym stands for Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, and Kingella: all HACEK members are fastidious Gram-negative bacteria associated with infective endocarditis.

Where are HACEK organisms found in the body?

Aggregatibacter actinomycetemcomitans colonies develop a star-shaped structure after prolonged incubation. Cardiobacterium hominis was first described in 1962 and was isolated from patients with endocarditis. Like other HACEK organisms, C. hominis is found in the oropharynx but rarely the gastrointestinal tract.