Arcanobacterium haemolyticum

Arcanobacterium haemolyticum after 48 hours

Arcanobacterium haemolyticum is a species of Gram-positive bacteria that is known to cause pharyngitis and skin infections, particularly in adolescents and young adults. It was first described in 1946 by MacLean, Liebow, and Rosenberg. This bacterium is part of the genus Arcanobacterium, which includes several other species that are pathogenic to humans and animals.

Characteristics

Arcanobacterium haemolyticum is a facultative anaerobic bacterium, meaning it can grow in both the presence and absence of oxygen. It is non-motile and does not form spores. The bacterium is characterized by its ability to produce a beta-hemolytic reaction on blood agar, which is a key diagnostic feature. Colonies of A. haemolyticum are typically small, white, and exhibit a narrow zone of hemolysis after 48 hours of incubation.

Pathogenesis

Arcanobacterium haemolyticum is primarily associated with pharyngitis, which is an inflammation of the pharynx causing a sore throat. It can also cause skin infections, such as cellulitis and ulcers. The bacterium is known to produce a phospholipase D toxin, which contributes to its virulence by damaging host cell membranes.

Clinical Presentation

Patients infected with A. haemolyticum often present with symptoms similar to those of streptococcal pharyngitis, including sore throat, fever, and lymphadenopathy. A distinguishing feature of A. haemolyticum infection is the presence of a scarlatiniform rash, which can help differentiate it from other causes of pharyngitis.

Diagnosis

Diagnosis of Arcanobacterium haemolyticum infection is typically made through culture of the organism from throat swabs or skin lesions. The bacterium's characteristic beta-hemolytic colonies on blood agar and its Gram-positive, rod-shaped appearance under the microscope aid in identification. Molecular methods, such as PCR, can also be used for more rapid and specific detection.

Treatment

Infections caused by Arcanobacterium haemolyticum are generally treated with antibiotics. The bacterium is usually susceptible to penicillin, erythromycin, and clindamycin. It is important to accurately diagnose and treat infections to prevent complications and transmission.

Epidemiology

Arcanobacterium haemolyticum is most commonly isolated from adolescents and young adults, particularly those aged 10 to 30 years. It is less frequently found in older adults and young children. The bacterium is transmitted through respiratory droplets, and outbreaks can occur in close-contact settings such as schools and military barracks.

Prevention

Preventive measures for A. haemolyticum infections include good hygiene practices, such as regular handwashing and avoiding close contact with infected individuals. In healthcare settings, standard infection control procedures should be followed to prevent nosocomial transmission.

Related Pages

• Pharyngitis
• Gram-positive bacteria
• Beta-hemolysis
• Antibiotic treatment