title: Invasive infections of Aggregatibacter (Actinobacillus) actinomycetemcomitans.
abstract: OBJECTIVE
  Aggregatibacter (Actinobacillus) actinomycetemcomitans, part of the normal flora of the mouth, is frequently found in human periodontal cultures and is an important pathogen causing various invasive infections, particularly infective endocarditis. In this study, we describe the clinical course and outcome of patients with A. actinomycetemcomitans infection.
  
  
  METHODS
  All patients suffering invasive A. actinomycetemcomitans infections at the National Taiwan University Hospital from January 1985 to December 2004 were included in this study. Relevant data regarding clinical presentation, antimicrobial treatment and outcome of these patients were analyzed.
  
  
  RESULTS
  During the study period, there were 11 patients with invasive A. actinomycetemcomitans infections, including eight patients with infective endocarditis, one with osteonecrosis and two with pneumonia and chest wall lesions. Among the patients with infective endocarditis, four had prosthetic valve replacement, four suffered from rheumatic heart disease and one had undergone surgical repair of ventricular septal defect. Lesions in the oral cavity were the probable portals of entry of the microorganism, and included carious teeth, periodontitis or radiotherapy of the ear-nose-throat field, and were noted in nine patients. Transthoracic echocardiography and/or transesophageal echocardiography were performed on the patients with probable infective endocarditis but growth was demonstrated in only four of these patients. Blood culture yielded A. actinomycetemcomitans after prolonged incubation. Three isolates were resistant to penicillin and two of these were also resistant to ampicillin.
  
  
  CONCLUSIONS
  The diagnosis of invasive A. actinomycetemcomitans infection was delayed due to the indolent clinical course, non-specific presentation and slow growth of the organism. Antibiotic therapy using amoxicillin/clavulanic acid, ampicillin, ampicillin/sulbactam, ceftriaxone, clindamycin, cefotaxime, or levofloxacin was successful in all patients. None of the patients demonstrated recurrence of infection 2-36 months following treatment.
authors.affiliation: Department of Internal Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan.
authors.forename: Cheng-Yi
authors.initials: CY
authors.lastname: Wang
authors.forename: Hui-Chih
authors.initials: HC
authors.lastname: Wang
authors.forename: Jang-Ming
authors.initials: JM
authors.lastname: Li
authors.forename: Jen-Yu
authors.initials: JY
authors.lastname: Wang
authors.forename: Kai-Chien
authors.initials: KC
authors.lastname: Yang
authors.forename: Yi-Kwun
authors.initials: YK
authors.lastname: Ho
authors.forename: Pei-Ying
authors.initials: PY
authors.lastname: Lin
authors.forename: Li-Na
authors.initials: LN
authors.lastname: Lee
authors.forename: Chong-Jen
authors.initials: CJ
authors.lastname: Yu
authors.forename: Pan-Chyr
authors.initials: PC
authors.lastname: Yang
authors.forename: Po-Ren
authors.initials: PR
authors.lastname: Hsueh
mesh_terms: D000189:Actinobacillus Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology / Q000503:physiopathology*; D000328:Adult; D000368:Aged; D016976:Aggregatibacter actinomycetemcomitans / Q000302:isolation & purification / Q000472:pathogenicity*; D015984:Causality; D004452:Echocardiography; D004697:Endocarditis, Bacterial / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D005260:Female; D006785:Hospitals, University / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010020:Osteonecrosis / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D018410:Pneumonia, Bacterial / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D013624:Taiwan / Q000453:epidemiology