''Arcanobacterium haemolyticum'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometr ...

classified as a

gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bact ...

bacillus. It is catalase-negative, facultative

anaerobic Anaerobic means "living, active, occurring, or existing in the absence of free oxygen", as opposed to aerobic which means "living, active, or occurring only in the presence of oxygen." Anaerobic may also refer to: * Anaerobic adhesive, a bonding a ...

beta-hemolytic ''Streptococcus'' is a genus of gram-positive ' (plural ) or spherical bacteria that belongs to the family Streptococcaceae, within the order Lactobacillales (lactic acid bacteria), in the phylum Bacillota. Cell division in streptococci occurs ...

, and not

motile Motility is the ability of an organism to move independently, using metabolic energy. Definitions Motility, the ability of an organism to move independently, using metabolic energy, can be contrasted with sessility, the state of organisms th ...

. It has been known to cause head and neck infections,

pharyngitis Pharyngitis is inflammation of the back of the throat, known as the pharynx. It typically results in a sore throat and fever. Other symptoms may include a Rhinorrhea, runny nose, cough, headache, difficulty swallowing, swollen lymph nodes, and a ...

, and

sinusitis Sinusitis, also known as rhinosinusitis, is inflammation of the mucous membranes that line the sinuses resulting in symptoms that may include thick nasal mucus, a plugged nose, and facial pain. Other signs and symptoms may include fever, head ...

( ''Arcanobacterium haemolyticum'' infections).

History

It was first described by MacClean et al. in 1946 from US servicemen and peoples of the South Pacific suffering from

sore throat Sore throat, also known as throat pain, is pain or irritation of the throat. Usually, causes of sore throat include * viral infections * group A streptococcal infection (GAS) bacterial infection * pharyngitis (inflammation of the throat) * to ...

. Due to its resemblance to another genus of bacteria, '' Corynebacterium'', ''A. haemolyticum'' was initially classified as ''C. pyogenes'' subspecies ''hominus''. It was known for several decades as ''Corynebacterium haemolyticum''; controversies regarding classification were resolved in 1982 when a new genus, ''

Arcanobacterium ''Arcanobacterium'' () is a genus of bacteria. They are gram-positive, non– acid fast, nonmotile, facultatively anaerobic, and non–endospore forming. They are widely distributed in nature in the microbiota of animals (including the human mic ...

'', was created by Collins et al. to reclassify ''Corynebacterium haemolyticum'' on the basis of its

peptidoglycan Peptidoglycan or murein is a unique large macromolecule, a polysaccharide, consisting of sugars and amino acids that forms a mesh-like peptidoglycan layer outside the plasma membrane, the rigid cell wall (murein sacculus) characteristic of most ba ...

fatty acid In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, ...

, and DNA characteristics. Since its initial description, the spectrum of diseases caused by ''A. haemolyticum'' has been expanded to include

sepsis Sepsis, formerly known as septicemia (septicaemia in British English) or blood poisoning, is a life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. This initial stage is follo ...

and

osteomyelitis Osteomyelitis (OM) is an infection of bone. Symptoms may include pain in a specific bone with overlying redness, fever, and weakness. The long bones of the arms and legs are most commonly involved in children e.g. the femur and humerus, while the ...

. Organisms are Gram-positive, facultative

, catalase-negative rods (but transition to the coccal shape occurs as the organism grows) with arrangements described as matchbox or Chinese letters arrangements. Growth is enhanced in blood and by

carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...

Detection

Hemolysis Hemolysis or haemolysis (), also known by several other names, is the rupturing ( lysis) of red blood cells (erythrocytes) and the release of their contents (cytoplasm) into surrounding fluid (e.g. blood plasma). Hemolysis may occur in vivo ...

is detected on human blood agar plates, and routine plating of specimens suspected of containing ''A. haemolyticum'' on human blood agar is suggested to distinguish it from ''

Streptococcus pyogenes ''Streptococcus pyogenes'' is a species of Gram-positive, aerotolerant bacteria in the genus '' Streptococcus''. These bacteria are extracellular, and made up of non-motile and non-sporing cocci (round cells) that tend to link in chains. They ...

'', as ''A. haemolyticum'' can easily be confused with this organism. Microscopic morphology differences can be used to differentiate them, since ''Arcanobacterium'' is rod-shaped and ''Streptococcus'' is coccus-shaped. ''A. haemolyticum'' infection is most common in 15- to 25-year-old persons and manifests as exudative

and/or

tonsillitis Tonsillitis is inflammation of the tonsils in the upper part of the throat. It can be acute or chronic. Acute tonsillitis typically has a rapid onset. Symptoms may include sore throat, fever, enlargement of the tonsils, trouble swallowing, and en ...

accompanied by cervical lymphadenopathy. Symptoms look like those of β-hemolytic streptococci or viral infection. A rash of the chest and of the abdomen, neck, or extremities is seen in 20% to 25% of cases, enhancing the risk of diagnostic error as streptococcal infection or penicillin allergy, when β-lactam therapy is initiated without exact diagnosis. ''A. haemolyticum'' often occurs in polymicrobic infections together with typical respiratory

pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...

s such as streptococci. The isolation of classical pathogens from specimens that also contain ''A. haemolyticum'' might be in part responsible for the tendency to miss the organism.

Pathology

''A. haemolyticum'' is the cause of pharyngitis (sore throat) in up to 2.5% of cases. In one study, it was the causative agent of pharyngitis in 1.4% of military conscripts. It is rarely found in the skin or throat of healthy people, meaning it is not a member of the usual bacterial flora. Little is known about the means by which ''A. haemolyticum'' causes infection or the associated skin manifestations. The organism is known to produce uncharacterized hemolytic agent(s), a

neuraminidase Exo-α-sialidase (EC 3.2.1.18, sialidase, neuraminidase; systematic name acetylneuraminyl hydrolase) is a glycoside hydrolase that cleaves the glycosidic linkages of neuraminic acids: : Hydrolysis of α-(2→3)-, α-(2→6)-, α-(2→8)- glyc ...

and a

phospholipase A phospholipase is an enzyme that hydrolyzes phospholipids into fatty acids and other lipophilic substances. Acids trigger the release of bound calcium from cellular stores and the consequent increase in free cytosolic Ca2+, an essential step in ...

D (PLD) acting preferentially on

sphingomyelin Sphingomyelin (SPH, ˌsfɪŋɡoˈmaɪəlɪn) is a type of sphingolipid found in animal cell membranes, especially in the membranous myelin sheath that surrounds some nerve cell axons. It usually consists of phosphocholine and ceramide, or a phosp ...

. PLD is known to result in tissue damage, but the role in disease of the cytotoxic effect caused by this extracellular toxin is not established.

Pyothorax Pleural empyema is a collection of pus in the pleural cavity caused by microorganisms, usually bacteria. Often it happens in the context of a pneumonia, injury, or chest surgery. It is one of the various kinds of pleural effusion. There are three ...

has been reported.

Treatment

''A. haemolyticum'' isolated from humans is susceptible to erythromycin (proposed as the first-line drug), clindamycin, gentamicin, and cephalosporins. The use of parenteral antimicrobial drugs must be limited to serious infections.

References

External links