title: Methicillin-resistant Staphylococcus aureus (MRSA) nasal real-time PCR: a predictive tool for contamination of the hospital environment.
abstract: OBJECTIVE We sought to determine whether the bacterial burden in the nares, as determined by the cycle threshold (CT) value from real-time MRSA PCR, is predictive of environmental contamination with MRSA. METHODS Patients identified as MRSA nasal carriers per hospital protocol were enrolled within 72 hours of room admission. Patients were excluded if (1) nasal mupirocin or chlorhexidine body wash was used within the past month or (2) an active MRSA infection was suspected. Four environmental sites, 6 body sites and a wound, if present, were cultured with premoistened swabs. All nasal swabs were submitted for both a quantitative culture and real-time PCR (Roche Lightcycler, Indianapolis, IN). RESULTS At study enrollment, 82 patients had a positive MRSA-PCR. A negative correlation of moderate strength was observed between the CT value and the number of MRSA colonies in the nares (r=-0.61; P<0.01). Current antibiotic use was associated with lower levels of MRSA nasal colonization (CT value, 30.2 vs 27.7; P<0.01). Patients with concomitant environmental contamination had a higher median log MRSA nares count (3.9 vs 2.5, P=0.01) and lower CT values (28.0 vs 30.2; P<0.01). However, a ROC curve was unable to identify a threshold MRSA nares count that reliably excluded environmental contamination. CONCLUSIONS Patients with a higher burden of MRSA in their nares, based on the CT value, were more likely to contaminate their environment with MRSA. However, contamination of the environment cannot be predicted solely by the degree of MRSA nasal colonization.
authors: Daniel J
authors: DJ
authors: Livorsi
authors: 1Richard Roudebush VA Medical Center,Indianapolis,IN.
authors: David J
authors: DJ
authors: Livorsi
authors: 2Division of Infectious Diseases,Indiana University School of Medicine,Indianapolis,IN.
authors: Sana
authors: S
authors: Arif
authors: 1Richard Roudebush VA Medical Center,Indianapolis,IN.
authors: Patricia
authors: P
authors: Garry
authors: 3Indiana University Fairbanks School of Public Health,Department of Biostatistics,Indianapolis,IN.
authors: Madan G
authors: MG
authors: Kundu
authors: 4Division of Infectious Diseases,Emory University School of Medicine,Atlanta,GA.
authors: Sarah W
authors: SW
authors: Satola
authors: 6Division of Microbiology,Indiana University School of Medicine,Indianapolis,IN.
authors: Thomas H
authors: TH
authors: Davis
authors: 1Richard Roudebush VA Medical Center,Indianapolis,IN.
authors: Byron
authors: B
authors: Batteiger
authors: 2Division of Infectious Diseases,Indiana University School of Medicine,Indianapolis,IN.
authors: Amy B
authors: AB
authors: Kressel
mesh_terms: D034861:Abdominal Wall / Q000382:microbiology; D000368:Aged; D001365:Axilla / Q000382:microbiology; D002353:Carrier State / Q000175:diagnosis* / Q000382:microbiology; D015169:Colony Count, Microbial; D005260:Female; D050456:Fomites / Q000382:microbiology*; D005542:Forearm / Q000382:microbiology; D006119:Groin / Q000382:microbiology; D006801:Humans; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000235:genetics; D008875:Middle Aged; D009666:Nose / Q000382:microbiology*; D010362:Patients' Rooms; D011237:Predictive Value of Tests; D012372:ROC Curve; D060888:Real-Time Polymerase Chain Reaction; D012867:Skin / Q000382:microbiology*; D035441:Thoracic Wall / Q000382:microbiology
references: Infect Control Hosp Epidemiol. 2006 Feb;27(2):181-4
references: 16465635
references: Ann Intern Med. 2008 Mar 18;148(6):409-18
references: 18347349
references: Infect Control Hosp Epidemiol. 2007 Oct;28(10):1142-7
references: 17828690
references: Clin Infect Dis. 2006 Oct 15;43(8):971-8
references: 16983607
references: Infect Control Hosp Epidemiol. 2008 Aug;29(8):702-8, 7 p following 708
references: 18624651
references: J Antimicrob Chemother. 2008 Dec;62(6):1422-9
references: 18765411
references: Int J Hyg Environ Health. 2009 Mar;212(2):209-15
references: 18667356
references: Pharmacotherapy. 2009 Mar;29(3):263-80
references: 19249946
references: Infect Control Hosp Epidemiol. 2009 Apr;30(4):313-8
references: 19239380
references: Infect Control Hosp Epidemiol. 2010 Jan;31(1):42-6
references: 19954335
references: Infect Control Hosp Epidemiol. 2010 Jun;31(6):607-12
references: 20397963
references: Infect Control Hosp Epidemiol. 2010 Aug;31(8):786-95
references: 20524852
references: Infect Control Hosp Epidemiol. 2011 Jan;32(1):1-8
references: 21133794
references: J Clin Microbiol. 2011 Mar;49(3):1119-21
references: 21209169
references: N Engl J Med. 2011 Apr 14;364(15):1419-30
references: 21488764
references: Ann Emerg Med. 2011 May;57(5):492-9
references: 21239081
references: Clin Microbiol Infect. 2012 Feb;18(2):E31-3
references: 22192160
references: Crit Care Med. 2012 Apr;40(4):1045-51
references: 22202707
references: J Clin Microbiol. 2012 Jun;50(6):2079-81
references: 22442322
references: Infect Control Hosp Epidemiol. 2012 Aug;33(8):803-8
references: 22759548
references: Lancet Infect Dis. 2005 Dec;5(12):751-62
references: 16310147
references: J Lab Clin Med. 1961 Aug;58:273-7
references: 13784805
references: Br Med J. 1959 Jan 31;1(5117):270-3
references: 13618615
references: Infect Control Hosp Epidemiol. 1997 Sep;18(9):622-7
references: 9309433
references: N Engl J Med. 1986 Jul 10;315(2):91-6
references: 3523240
references: Infect Control Hosp Epidemiol. 2004 May;25(5):395-401
references: 15188845
references: J Clin Microbiol. 2003 Nov;41(11):5113-20
references: 14605147