Interpretive Handbook

Test 8221 :
Actinomyces Culture

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Anaerobic Actinomyces are nonsporeforming, thin branching, gram-positive bacilli that are part of the normal flora of the human oral cavity and may also colonize the gastrointestinal and female genital tracts. Their presence is important in preserving the usual bacterial populations of the mouth and in preventing infection with pathogenic bacteria.


Actinomyces are generally of low pathogenicity but may be an important factor in the development of periodontal disease and may cause soft tissue infections in colonized areas of the body following trauma (surgical or otherwise). The typical lesion consists of an outer zone of granulation around central purulent loculations containing masses of tangled organisms ("sulfur granule"). Chronic burrowing sinus tracts develop. Typical actinomycotic infections occur around the head and neck, in the lung and chest wall, and in the peritoneal cavity and abdominal wall. Actinomycosis of the female genital tract occurs in association with use of intrauterine contraceptive devices. Purulent collections containing "sulfur granules" may drain from some sinus tracts opening to the skin.

Useful For Suggests clinical disorders or settings where the test may be helpful

Diagnosing anaerobic Actinomyces involved in infections

Interpretation Provides information to assist in interpretation of the test results

Isolation of anaerobic Actinomyces in significant numbers from well collected specimens including blood, other normally sterile body fluids, or closed collections of purulent fluid indicates infection with the identified organism.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Specimens should be collected by needle and syringe aspiration or surgical drainage to avoid contamination with normal-flora Actinomyces, especially in and around the oral cavity; such contamination would make interpretation of culture results impossible.


Specimens must be transported in anaerobic transport vials.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

No growth

Identification of probable pathogens

Clinical References Provides recommendations for further in-depth reading of a clinical nature

1. Summanen P, Baron EJ, Citron DM, Jousimies-Somer HR, et al: Wadsworth Anaerobic Bacteriology Manual, Sixth edition. Belmont CA, Star Publishing Co. 2002

2.. Hall V, Copsey SD: Propionibacterium, Lactobacillus, Actinomyces, and Other Non-Spore-Forming Anaerobic Gram-Positive Rods. In Manual of Clinical Microbiology. 11th edition. Edited by J Jorgensen. Washington DC, ASM Press, 2015 Chapters 52, pp 920-939

3. Morton A, Hall, GS: Anaerobic Gram-Positive Bacilli. In Clinical Microbiology Procedures Handbook. Third edition. Vol. 1. Edited by LS Garcia. Washington DC, ASM Press, 2010