title: Low-grade infections in nonarthroplasty shoulder surgery.
abstract: BACKGROUND
  Recent studies have identified the diagnostic challenge of low-grade infections after shoulder arthroplasty surgery. Infections after nonarthroplasty procedures have not been reported. This study assessed patient-related risk factors, outcomes, and clinical presentation of low-grade infection after open and arthroscopic nonarthroplasty shoulder surgery.
  
  
  METHODS
  The cases of 35 patients presenting with suspected low-grade infection were reviewed. Biopsy specimens taken at revision surgery were cultured in the sterile environment of a class II laminar flow cabinet and incubated for a minimum of 14 days at a specialist orthopedic microbiology laboratory. Patient-related factors (age, occupation, injection), index surgery, and infection characteristics (onset of symptoms, duration to diagnosis, treatment) were analyzed.
  
  
  RESULTS
  Positive cultures were identified in 21 cases (60.0%), of which 15 were male patients (71%). Of all patients with low-grade infection, 47.6% were male patients between 16 and 35 years of age. Propionibacterium acnes and coagulase-negative staphylococcus were the most common organisms isolated (81.1% [n = 17] and 23.8% [n = 5], respectively). Of 14 negative culture cases, 9 were treated with early empirical antibiotics (64.3%); 7 patients reported symptomatic improvement (77.8%). Of 5 patients treated with late empirical antibiotics, 4 stated improvement. Patients presented with symptoms akin to resistant postoperative frozen shoulder (persistent pain and stiffness, unresponsive to usual treatments).
  
  
  CONCLUSIONS
  Young male patients are at greatest risk for low-grade infections after arthroscopic and open nonarthroplasty shoulder surgery. P. acnes was the most prevalent organism. Patients presented with classic postoperative frozen shoulder symptoms, resistant to usual treatments. Interestingly, 78.6% of patients with negative cultures responded positively to empirical treatment.
authors.affiliation: University of Manchester, Faculty of Biology, Medicine and Health, Manchester, UK.
authors.forename: Umair
authors.initials: U
authors.lastname: Khan
authors.affiliation: The Arm Clinic at Wilmslow Hospital, Wilmslow, UK.
authors.forename: Emma
authors.initials: E
authors.lastname: Torrance
authors.affiliation: UKOMS Medical LTD, Sheffield, UK.
authors.forename: Robert
authors.initials: R
authors.lastname: Townsend
authors.affiliation: UKOMS Medical LTD, Sheffield, UK.
authors.forename: Steve
authors.initials: S
authors.lastname: Davies
authors.affiliation: The Arm Clinic at Wilmslow Hospital, Wilmslow, UK.
authors.forename: Tanya
authors.initials: T
authors.lastname: Mackenzie
authors.affiliation: The Arm Clinic at Wilmslow Hospital, Wilmslow, UK; Wrightington Hospital, Wigan, UK; University of Salford, School of Health Sciences, Manchester, UK. Electronic address: lenfunk@shoulderdoc.co.uk.
authors.forename: Lennard
authors.initials: L
authors.lastname: Funk
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D001182:Arthroscopy / Q000009:adverse effects*; D003030:Coagulase / Q000378:metabolism; D005260:Female; D016908:Gram-Positive Bacterial Infections / Q000175:diagnosis / Q000382:microbiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000175:diagnosis / Q000382:microbiology*; D011425:Propionibacterium acnes / Q000302:isolation & purification*; D012086:Reoperation; D012189:Retrospective Studies; D012307:Risk Factors; D012785:Shoulder Joint / Q000382:microbiology / Q000601:surgery*; D013203:Staphylococcal Infections / Q000175:diagnosis / Q000382:microbiology*; D013210:Staphylococcus / Q000201:enzymology; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D003030:Coagulase
keywords: Nonarthroplasty; Propionibacterium acnes; arthroscopic; complications; low-grade infection; shoulder