title: Pyomyositis: Are We Missing the Diagnosis?
abstract: BACKGROUND
  Pyomyositis (PY) is a primary infection of the skeletal muscles, leading to inflammation of the muscle fibers followed by pus formation and even necrosis in late stages. Because of overlap in presentation of intermuscular abscess (IM) and PY, the exact incidence and severity of PY is under-appreciated.
  
  
  METHODS
  We conducted a prospective analytical study in a tertiary care center in North India from October 2011 to January 2013, recruiting patients with abscesses involving the chest wall, abdomen (parietal wall including back), and extremities. Subcutaneous, hepatic, intra-abdominal abscess, and secondary abscesses were excluded. Primary PY was defined as a primary infection of skeletal muscle without any foci from adjacent skin, soft tissue, or bone. Clinical, radiologic, pathologic, and operative findings suggested diagnosis; loss of striations and lymphocytic infiltration in the muscle fibers was confirmatory. The chief outcome variables were death and length of hospital stay.
  
  
  RESULTS
  Thirty patients with a mean age of 29.5 y (IM: 29.7 ± 16.7, PY: 25.28 ± 17.6) were classified as IM (18/30, 60%) or PY (12/30, 40%). Most PY occurred in the lower limb (41.7% had multi-site involvement); most had a history of trauma or immunocompromised state. Fever, tachycardia, tachypnea, hypotension, pallor, and hyperesthesia were significantly higher (p < 0.05) in PY. Mean Sequential Organ Failure Assessment (SOFA) score was 0.33 for IM, 2.5 for PY. Staphylococcus aureus was predominant in both groups; however, all four patients with methicillin-resistant S. aureus (MRSA) were in the PY group. Both deaths also occurred in the PY group. The mean duration of hospital stay was 3.22 ± 1.11 d for IM and 10.27 ± 2.32 d for PY patients (p = 0.03).
  
  
  CONCLUSIONS
  PY is a specific and potentially fatal infection, which is common in our country and must be differentiated from IM. A high index of suspicion and early institution of specific antibiotics followed by operation is therapeutic.
authors.affiliation: Department of Surgery, University College of Medical Sciences and Guru Tegh Bahadur Hospital , Delhi, India .
authors.forename: Nitin
authors.initials: N
authors.lastname: Agarwal
authors.affiliation: Department of Surgery, University College of Medical Sciences and Guru Tegh Bahadur Hospital , Delhi, India .
authors.forename: Shashank
authors.initials: S
authors.lastname: Aroor
authors.affiliation: Department of Surgery, University College of Medical Sciences and Guru Tegh Bahadur Hospital , Delhi, India .
authors.forename: Pradeep
authors.initials: P
authors.lastname: Saini
authors.affiliation: Department of Surgery, University College of Medical Sciences and Guru Tegh Bahadur Hospital , Delhi, India .
authors.forename: Arun
authors.initials: A
authors.lastname: Gupta
authors.affiliation: Department of Surgery, University College of Medical Sciences and Guru Tegh Bahadur Hospital , Delhi, India .
authors.forename: Navneet
authors.initials: N
authors.lastname: Kaur
mesh_terms: D000293:Adolescent; D000328:Adult; D003951:Diagnostic Errors; D005260:Female; D006801:Humans; D007194:India; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D052880:Pyomyositis / Q000175:diagnosis* / Q000453:epidemiology / Q000382:microbiology / Q000628:therapy; D012307:Risk Factors; D055815:Young Adult