title: MRSA-related perianal abscesses: an underrecognized disease entity.
abstract: OBJECTIVE
  Methicillin-resistant Staphylococcus aureus (MRSA) in perianal abscesses represents an underrecognized condition. It is unclear whether these abscesses differ in presentation or other characteristics from their non-MRSA counterparts.
  
  
  METHODS
  Patients diagnosed with perianal abscess, who underwent incision and drainage between January 2003 and September 2005, were identified retrospectively. Demographics, abscess characteristics (induration, erythema, abscess size, amount of purulence), presence of MRSA on culture, MRSA susceptibilities, and clinical course were collected.
  
  
  RESULTS
  A total of 104 patients (62.5 percent male; mean age, 42.7+/-13.7 years) were treated for perianal abscess. For the 69 patients cultured at drainage, MRSA was present in 34.8 percent (24/69) of cases (95 percent confidence interval, 24.6-46.6 percent). MRSA-positive patients did not significantly differ from MRSA-negative patients with respect to age, MRSA risk factors, duration of symptoms, white blood cell count at admission, or length of stay. Patients were more likely to be MRSA-positive if they possessed extensive induration (odds ratio, 6.52; P=0.003), extensive erythema (odds ratio, 5.75; P=0.003), or small amount of purulence (odds ratio, 9.72; P=0.006). Ischiorectal abscesses were significantly less likely to be MRSA-positive (odds ratio, 0.34; P=0.016). No patients with MRSA-positive abscesses developed fistulas. All MRSA isolates were resistant to beta-lactam antibiotics and had limited susceptibility to quinolones.
  
  
  CONCLUSIONS
  The prevalence of MRSA in perianal abscesses has not been described previously and is higher in our group of patients than would be expected. MRSA-positive patients cannot be identified by risk factors alone. Antibiotic resistance spectra of MRSA vary from that of enteric bacteria typically seen in perianal abscesses. Therefore, it may be beneficial to culture all perianal abscesses with extensive induration and erythema or minimal purulence.
authors.affiliation: University of Texas Affiliated Hospitals, 6550 Fannin Street, Suite 2307, Houston, Texas 77030, USA. jb_albright@hotmail.com
authors.forename: Jeffrey B
authors.initials: JB
authors.lastname: Albright
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Pidala
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Cali
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Snyder
authors.forename: Theodoros
authors.initials: T
authors.lastname: Voloyiannis
authors.forename: H Randolph
authors.initials: HR
authors.lastname: Bailey
mesh_terms: D000038:Abscess / Q000175:diagnosis / Q000382:microbiology* / Q000628:therapy; D000328:Adult; D000890:Anti-Infective Agents / Q000627:therapeutic use; D001004:Anus Diseases / Q000175:diagnosis / Q000382:microbiology* / Q000628:therapy; D004322:Drainage; D005260:Female; D006801:Humans; D008297:Male; D016106:Methicillin Resistance; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D013203:Staphylococcal Infections / Q000175:diagnosis / Q000382:microbiology* / Q000628:therapy; D013211:Staphylococcus aureus / Q000187:drug effects / Q000302:isolation & purification*
chemical_list: D000890:Anti-Infective Agents