title: Acute haematogenous community-acquired methicillin-resistant Staphylococcus aureus osteomyelitis in an adult: case report and review of literature.
abstract: BACKGROUND
  Methicillin-resistant Staphylococcus aureus (MRSA) has of late emerged as a cause of community-acquired infections among immunocompetent adults without risk factors. Skin and soft tissue infections represent the majority of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) clinical presentations, whilst invasive and life-threatening illness like necrotizing pneumonia, necrotizing fasciitis, pyomyositis, osteomyelitis and sepsis syndrome are less common. Although more widely described in the pediatric age group, the occurrence of CA-MRSA osteomyelitis in adults is an uncommonly reported entity.
  
  
  METHODS
  We describe an invasive CA-MRSA infection in a 28 year-old previously healthy male, manifesting with bacteraemia, osteomyelitis of femur, pyomyositis and septic arthritis of the knee. Initially a preliminary diagnosis of osteosarcoma was suggested by imaging studies and patient underwent a bone biopsy. MRSA was subsequently isolated from blood cultures taken on day of admission, bone, tissue and pus cultures. Incision and drainage of abscess was performed and patient was treated with vancomycin, with fusidic acid added later. It took 6 months for the inflammatory markers to normalize, warranting 6-months of anti-MRSA therapy. Patient was a fervent deer hunter and we speculate that he acquired this infection from extensive direct contact with deer.Molecular characterization of this isolate showed that it belonged to multilocus sequence type (MLST) ST30 and exhibited the staphylococcal chromosome cassette mec (SCCmec) type IV, staphylococcus protein A (spa) type t019, accessory gene regulator (agr) type III and dru type dt10m. This strain harbored Panton-Valentine leukocidin (pvl) genes together with 3 other virulent genes; sei (enterotoxin), hlg (hemolysin) and fnbA (fibronectin binding protein).
  
  
  CONCLUSIONS
  This case study alerts physicians that beyond the most commonly encountered skin and soft tissue infections, pvl positive CA-MRSA can lead to invasive life-threatening disease especially in an immunocompetent adult. Heightened alertness is needed for osteomyelitis of long bones in adults, as it is not uncommon for this disease to mimic primary bone malignancy. Cure is achievable with early appropriate antibiotics guided by inflammatory markers.
authors.affiliation: Jeffrey Cheah School of Medicine and Health Sciences, Monash University Sunway Campus, Bandar Sunway, Malaysia. amreeta.dhanoa@monash.edu
authors.forename: Amreeta
authors.initials: A
authors.lastname: Dhanoa
authors.forename: Vivek Ajit
authors.initials: VA
authors.lastname: Singh
authors.forename: Azura
authors.initials: A
authors.lastname: Mansor
authors.forename: Mohd Yasim
authors.initials: MY
authors.lastname: Yusof
authors.forename: King-Ting
authors.initials: KT
authors.lastname: Lim
authors.forename: Kwai-Lin
authors.initials: KL
authors.lastname: Thong
mesh_terms: D000328:Adult; D016470:Bacteremia / Q000175:diagnosis* / Q000382:microbiology / Q000473:pathology; D017714:Community-Acquired Infections / Q000175:diagnosis* / Q000382:microbiology / Q000473:pathology; D005838:Genotype; D006801:Humans; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D058885:Multilocus Sequence Typing; D010019:Osteomyelitis / Q000175:diagnosis* / Q000382:microbiology / Q000473:pathology; D013203:Staphylococcal Infections / Q000175:diagnosis* / Q000382:microbiology / Q000473:pathology; D037521:Virulence Factors / Q000235:genetics
chemical_list: D037521:Virulence Factors