title: Presence of Bacteria in Spontaneous Achilles Tendon Ruptures.
abstract: BACKGROUND
  The structural pathology of Achilles tendon (AT) ruptures resembles tendinopathy, but the causes remain unknown. Recently, a number of diseases were found to be attributed to bacterial infections, resulting in low-grade inflammation and progressive matrix disturbance. The authors speculate that spontaneous AT ruptures may also be influenced by the presence of bacteria.
  
  
  OBJECTIVE
  Bacteria are present in ruptured ATs but not in healthy tendons.
  
  
  METHODS
  Cross-sectional study; Level of evidence, 3.
  
  
  METHODS
  Patients with spontaneous AT ruptures and patients undergoing anterior cruciate ligament (ACL) reconstruction were recruited for this study. During AT surgical repair, excised tendinopathic tissue was collected, and healthy tendon samples were obtained as controls from hamstring tendon grafts used in ACL reconstruction. Half of every sample was reserved for DNA extraction and the other half for histology. Polymerase chain reaction (PCR) was conducted using 16S rRNA gene universal primers, and the PCR products were sequenced for the identification of bacterial species. A histological examination was performed to compare tendinopathic changes in the case and control samples.
  
  
  RESULTS
  Five of 20 AT rupture samples were positive for the presence of bacterial DNA, while none of the 23 hamstring tendon samples were positive. Sterile operating and experimental conditions and tests on samples, controlling for harvesting and processing procedures, ruled out the chance of postoperative bacterial contamination. The species identified predominantly belonged to the Staphylococcus genus. AT rupture samples exhibited histopathological features characteristic of tendinopathy, and most healthy hamstring tendon samples displayed normal tendon features. There were no apparent differences in histopathology between the bacterial DNA-positive and bacterial DNA-negative AT rupture samples.
  
  
  CONCLUSIONS
  The authors have demonstrated the presence of bacterial DNA in ruptured AT samples. It may suggest the potential involvement of bacteria in spontaneous AT ruptures.
authors.affiliation: Division of Orthopaedics and Biotechnology, Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden.|Lui Che Woo Institute of Innovative Medicine, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Christer G
authors.initials: CG
authors.lastname: Rolf
authors.affiliation: Lui Che Woo Institute of Innovative Medicine, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.|Department of Orthopaedics and Traumatology, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Sai-Chuen
authors.initials: SC
authors.lastname: Fu
authors.affiliation: Lui Che Woo Institute of Innovative Medicine, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.|Department of Orthopaedics and Traumatology, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Chelsea
authors.initials: C
authors.lastname: Hopkins
authors.affiliation: Department of Orthopaedics and Traumatology, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Ju
authors.initials: J
authors.lastname: Luan
authors.affiliation: Department of Microbiology, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Margaret
authors.initials: M
authors.lastname: Ip
authors.affiliation: Lui Che Woo Institute of Innovative Medicine, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.|Department of Orthopaedics and Traumatology, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Shu-Hang
authors.initials: SH
authors.lastname: Yung
authors.affiliation: Section of Infectious Diseases, Department of Medical Sciences, Uppsala University, Uppsala, Sweden.
authors.forename: Göran
authors.initials: G
authors.lastname: Friman
authors.affiliation: Department of Orthopaedics and Traumatology, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.|Musculoskeletal Research Laboratory, Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Hong Kong, China.|Translational Medicine Research and Development Center, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Qin
authors.affiliation: Lui Che Woo Institute of Innovative Medicine, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.|Department of Orthopaedics and Traumatology, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Kai-Ming
authors.initials: KM
authors.lastname: Chan
mesh_terms: D000125:Achilles Tendon / Q000293:injuries / Q000382:microbiology* / Q000601:surgery; D000328:Adult; D000368:Aged; D016118:Anterior Cruciate Ligament / Q000382:microbiology / Q000601:surgery; D059549:Anterior Cruciate Ligament Reconstruction; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D003430:Cross-Sectional Studies; D005260:Female; D000070633:Hamstring Muscles / Q000601:surgery; D000070632:Hamstring Tendons / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D052256:Tendinopathy / Q000601:surgery; D013708:Tendon Injuries / Q000382:microbiology* / Q000601:surgery
keywords: 16S rRNA; Achilles tendon; bacteria; tendinopathy