title: Actinomyces meyeri, a Common Agent of Actinomycosis.
abstract: Actinomyces, particularly Actinomyces israelii, may cause indolent, persistent infections or represent normal mucosal flora, leading to management dilemmas.
  
  
  
  Prompted by a refractory Actinomyces meyeri infection complicating AIDS, clinical data for all Actinomyces isolates at our hospital laboratory since 1998 were analyzed.
  
  
  
  A total of 140 cases had a positive result for Actinomyces cultures. Of 130 cases with adequate follow-up, 36 (28%) cases had end-organ or disseminated disease treated with prolonged antibiotics or surgery or both (Group 1). A. meyeri was more common than A. israelii (33% versus 8%; P < 0.05) in Group 1, particularly thoracic infections. Another 56 (43%) cases were considered local pathogens, treated with drainage only or short-course antibiotics (Group 2). Another 38 (29%) cases were deemed commensals (Group 3). Immunosuppression was less frequent in Group 1 versus Group 2 or 3 (P = 0.05) and human immunodeficiency virus or AIDS was uncommon. Foreign bodies or devices (Group 1 versus Group 2 or 3, P = 0.003) and alcoholism (Group 1 versus Group 2 or 3; P = 0.03) were associated with actinomycosis. Isolates from the central nervous system and musculoskeletal sites were more often treated as definitive disease; skin, abdominal or pelvic or single blood culture isolates were more likely commensals (all P < 0.05). Disease progression or recurrence did not occur in Groups 2 and 3, whereas Group 1 had complex and variable courses, including 2 deaths.
  
  
  
  In the absence of disseminated or end-organ disease, avoiding prolonged therapy for Actinomyces isolates was not associated with adverse outcomes. Alcoholism or foreign bodies were associated with actinomycosis. A. meyeri may be a more common cause of actinomycosis than previously recognized.
authors.affiliation: Internal Medicine Residency Training Program, The University of Alabama of Birmingham, Birmingham, Alabama.
authors.forename: Robert
authors.initials: R
authors.lastname: Rolfe
authors.affiliation: Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina.
authors.forename: Lisa L
authors.initials: LL
authors.lastname: Steed
authors.affiliation: Department of Medicine, Medical University of South Carolina, Charleston, South Carolina. Electronic address: salgado@musc.edu.
authors.forename: Cassandra
authors.initials: C
authors.lastname: Salgado
authors.affiliation: Department of Pediatrics, Medical University of South Carolina, Charleston, South Carolina.
authors.forename: J Michael
authors.initials: JM
authors.lastname: Kilby
mesh_terms: D000163:Acquired Immunodeficiency Syndrome / Q000150:complications / Q000453:epidemiology; D000190:Actinomyces / Q000302:isolation & purification*; D000196:Actinomycosis / Q000150:complications / Q000453:epidemiology* / Q000382:microbiology*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D016377:Organ Transplantation / Q000009:adverse effects; D012189:Retrospective Studies; D012307:Risk Factors; D013022:South Carolina / Q000453:epidemiology; D055815:Young Adult
keywords: Actinomyces meyeri; Actinomycosis; Clinical outcomes; Epidemiology