Pathogen Safety Data Sheets: Infectious Substances – Actinomyces spp.


NAME: Actinomyces spp.

SYNONYM OR CROSS REFERENCE:, A. bovis, A. bowdenii, A. canis, A. israelii, A. denticolens, A. funkei, A. georgiae, A. gerencseriae, A. hominis, A. hongkongensis, A. hordeovulneris, A. howellii, A. hyovaginalis, A. johnsonii, A. massiliensis, A. meyeri, A. naeslundii, A. neuii, A. odontolyticus, A. oris, A, radicidentis,  A. radingae, A. slackii, A. suis, A. turicensis, A. viscosus, other Actinomyces species sensu stricto Footnote 1 .

CHARACTERISTICS: Actinomyces spp. belongs to the family Actinomycetaceae. They are gram positive rods, 0.4–1.0 µm in size that are straight, curved, or pleomorphic, and occur singly, in pairs, in clusters, or in short chains. Filaments (up to 50 µm in length) that are non-acid-fast and non-motile, do not form endospores or conidia, and grow well with media containing sodium carbonate Footnote 2. The majority of Actinomyces spp. are facultative anaerobes but some are anaerobic (A. suis).


PATHOGENICITY/TOXICITY: Actinomyces spp. are part of the normal flora of the oral cavity and respiratory tract, but infection of organs and bloodstream may occur upon disruption of tissue barriers Footnote 3. Actinomyces spp. are common in mixed infections, and infection with Actinomyces spp. alone is often associated with lower pathogenicity than when it is part of a mixed infection Footnote 4. Mixed infections predominantly involve A. israelii and A. gerencseriae, and based on the oral habitat of the genus, manifestations mostly occur in the cervicofacial region (but may occur at any area of the body) Footnote 5. A. israelii is known to cause actinomycosis, which is characterized by abscesses of the cervicofacial, thoracic, abdominopelvic regions, and central nervous system Footnote 6. A. naeslundii, A. meyeri, A. odontolyticus and A. viscosus are more rarely associated with actinomycosis Footnote 7. Infection is caused by invasion through a break in the mucous membrane, and the presence of devitalized tissue allows for deeper penetration into body tissues. Gastrointestinal infections often occur after surgery, intra-abdominal inflammation, trauma, or presence of foreign bodies, when the integrity of mucosal membranes is fragile. The spread of the bacterial infection after the initial invasion leads to chronic infection accompanied by draining sinuses and fibrosis. Secondary hepatic actinomycosis commonly occurs with abdominal or thoracic infections, and infections that dominantly affect the liver are rare but often serious Footnote 3. A. israelii has been discovered in the genital tract of healthy females, suggesting that it may be the cause of such infections, which are often related to the use of an intrauterine device. Actinomyces spp. has been linked to root surface caries and periodontal disease, both are widespread human illnesses. In root surface caries, species of Actinomyces can dominate the flora of lesions in root tissue of mainly elderly people, and it also aids in plaque development in periodontal diseases, which can lead to gingivitis.

EPIDEMIOLOGY: Actinomyces spp. are found worldwide with reported cases in Canada, USA, and India 89, although it is most commonly found in regions of low socioeconomic status and poor hygiene Footnote 6. Infection is rare in infants and children Footnote 8. Many cases are found in women using intra-uterine contraceptive device (IUCD) Footnote 9. Actinomycosis is three times more common in men than women Footnote 10. Alcoholism, intravenous drug abuse, peptic ulcer, and biliary tract disease are risk factors for hepatic actinomycosis Footnote 3.

HOST RANGE: Humans and animals, including pigs, dogs, cats,horses Footnote 7,cattle and marine mammals Footnote 1 Footnote 2 Footnote 7 Footnote 11.


MODE OF TRANSMISSION: The Actinomyces spp. commonly inhabits the oral cavity, the gastrointestinal tract, and the female genital tract, where they exist as commensals. Infection occurs when mechanical insult disrupts the mucosal barrier or organisms gain access to privileged sites. For example, actinomycosis commonly occurs after dental procedures, trauma, surgery, or aspiration Footnote 10. Actinomyces spp. is also presumed to be transmitted via direct contact between individuals as part of the normal oral flora Footnote 7.

INCUBATION PERIOD: The incubation period varies from several days to several years after colonization Footnote 7Footnote 8. The incubation period could be days to months after insult to a mucous membrane Footnote 7.

COMMUNICABILITY: The majority of infections result from Actinomyces spp. colonizing the hosts own oral or respiratory cavities Footnote 7 Footnote 11. It is presumed that Actinomyces can be transmitted from person-to-person via direct contact as part of the normal oral flora7.


RESERVOIR: Humans are the natural reservoir for Actinomyces spp., especially A. israelii Footnote 2 Footnote 7.  They are part of the normal oral flora and form a significant component of dental plaque on tooth surfaces Footnote 2. Actinomyces spp. are mostly found in intestinal surfaces and mucosal surfaces of humans and animals, blood, female and male genital and urinary tracts, actinomycotic lesions, and infectious hip prosthesis Footnote 2 Footnote 12.

ZOONOSIS: None known.

VECTOR: None known.


DRUG SUSCEPTIBILITY/RESISTANCE: Highly sensitive to β-lactam antibiotics, high to moderate sensitivity to tetracyclines, chloramphenicol, macrolides, lincomycins, fusidic acid and vancomycin. Actinomyces spp. do not generally develop antibiotic resistance, but some strains are resistant to aminoglycosides, peptide antibiotics, metronidazole, rifampicin (A. naeslundii).   

SUSCEPTIBILITY TO DISINFECTANTS: Bacteria have been shown to be susceptible to low concentrations of chlorine, 70 % ethanol, phenolics, 2% aqueous glutaraldehyde, and peracetic acid (0.001% to 0.2%) Footnote 13 Footnote 14.

PHYSICAL INACTIVATION: Inactivation is obtained by exposure to UV rays or by heating to 55-65 oC Footnote 15. Most bacteria can be inactivated by moist heat (121°C for 15 min - 30 min) and dry heat (160-170°C for 1-2 hours) Footnote 16.



SURVEILLANCE: Monitor for symptoms. The detection of ‘sulfur’ granules, Gram staining, and histological staining remain the principal methods of direct detection of Actinomyces spp. in clinical material Footnote 1. Immunofluorescent stains for Actinomyces spp. are available. Actinomyces spp. can be identified in tissue specimens using the 16s rRNA sequencing and PCR assay.
Note: All diagnostic methods are not necessarily available in all countries.

FIRST AID TREATMENT: Administer appropriate antibiotic therapy Footnote 7 Footnote 8. Prolonged therapy is necessary to achieve a cure and minimize relapse Footnote 10. Penicillin is usually effecting, but amoxicillin, erythromycin, clindamycin, doxycycline, and tetracycline are alternative antimicrobial choices Footnote 7. Tetracyclines are not recommended for pregnant women or children younger than 8 years of age. Surgical drainage often is a necessary adjunct to medical management and may allow for a shorter duration of antimicrobial treatment Footnote 8.




LABORATORY ACQUIRED INFECTIONS: One laboratory-acquired infection reported in 1976 Footnote 17.

SOURCES/SPECIMENS: Samples from oral cavity (dental plaque, saliva, mucosal surfaces), blood, tissue biopsy specimens, aspirates Footnote 2 Footnote 12.

PRIMARY HAZARD: Actinomyces spp. adapts to mucosal surfaces and has to penetrate through epithelial barrier to produce infection Footnote 18.



RISK GROUP CLASSIFICATION: Risk group 2 Footnote 19.  This risk group applies to the genus as a whole, and may not apply to every species within the genus.

CONTAINMENT REQUIREMENT: Containment Level 2 facilities, equipment, and operational practices for all work involving infectious or potentially infectious material Footnote 20. This containment level applies to the genus as a whole, and may not apply to every species within the genus.

PROTECTIVE CLOTHING: Lab coat. Gloves when direct skin contact with infected materials or animals is unavoidable. Eye protection must be used where there is a known or potential risk of exposure to splashesFootnote 20.

OTHER PRECAUTIONS: All procedures that may produce aerosols, or involve high concentrations or large volumes should be conducted in a biological safety cabinet (BSC). The use of needles, syringes, and other sharp objects should be strictly limited. Additional precautions should be considered with work involving animals or large scale activities.Footnote 20.


SPILLS: Allow aerosols to settle and, wearing protective clothing, gently cover spill with paper towels and apply an appropriate disinfectant, starting at the perimeter and working towards the centre. Allow sufficient contact time before clean upFootnote 20.

DISPOSAL: Decontaminate all wastes that contain or have come in contact with the infectious organism before disposing by autoclave, chemical disinfection, gamma irradiation, or incinerationFootnote 20.

STORAGE: The infectious agent should be stored in leak-proof containers that are appropriately labelledFootnote 20.


REGULATORY INFORMATION: The import, transport, and use of pathogens in Canada is regulated under many regulatory bodies, including the Public Health Agency of Canada, Health Canada, Canadian Food Inspection Agency, Environment Canada, and Transport Canada. Users are responsible for ensuring they are compliant with all relevant acts, regulations, guidelines, and standards.

UPDATED: November 2011

PREPARED BY: Pathogen Regulation Directorate, Public Health Agency of Canada.

Although the information, opinions and recommendations contained in this Pathogen Safety Data Sheet are compiled from sources believed to be reliable, we accept no responsibility for the accuracy, sufficiency, or reliability or for any loss or injury resulting from the use of the information. Newly discovered hazards are frequent and this information may not be completely up to date.

Copyright © Public Health Agency of Canada, 2011 Canada


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