1. A Countywide targeted surveillance/decolonization project in select
orthopedic patients utilizing PCR to detect MRSA
Jeanne Linquist, M.D., Bruce Fujikawa, DrPH, and Scott Morrow, MD, MPH
San Mateo County Health System, San Mateo, California
INTRODUCTION
Staphylococcus aureus (SA) is a serious cause of healthcare
associated infection (HAI)1
SA is designated either susceptible to methicillin (MSSA) or resistant
(MRSA)
Certain groups, conditions, or hospital associated procedures
constitute risk for MRSA infection or colonization. Nasal colonization
is associated with infection in some types of surgical procedures
Pre-operative intranasal mupirocin can eliminate nasal colonization and
decrease infection in patients undergoing some types of cardiac and
orthopedic surgery
We utilized the concept of public health practice4 to evaluate MRSA in
orthopedic patients scheduled to undergo total joint arthoplasty (TJA)
in San Mateo County (SMC) at any of six hospitals associated with four
different healthcare systems.
MATERIALS AND METHODS
1. Enlistment in the Project
Packets containing written procedures/instructions
pertinent to the project prepared for each individual
orthopedic surgeon.
Orthopedists recruited by telephone and provided
education at office
2. Sample Collection
Nasal specimens collected pre-operatively using BD
specimen collection kit.
Specimens stored at room temperature until transported
to the lab; any overnight storage was at 2 - 8degrees C.
Specimens picked up daily (fig.2) and received in the lab
by 1 PM
3. MRSA RT-PCR procedure
BD Real Time PCR IDI-MRSA assay performed with Cepheid SmartCycler (Fig 2) instrument according to manufacturer’s instructions.
Assay is one-step RT-PCR. Detection system is
fluorescent-based chemistry that uses fluorescent hybridization probes in the form of molecular beacons. Amplification target is Staphylococcal Cassette
Chromosome mec.
Total processing time is less than 2 hours.
Tests performed the day specimens received. Results
faxed same day
DISCUSSION
An important factor in the pathogenesis of staphylococcal infections is the ability of SA to establish nasal colonization5,6. Approximately 30% of the American population is colonized with SA in the anterior nares. MRSA colonization in the US was 0.8% in People with diabetes or renal failure may have colonization rates as high as 50%. Studies in pediatrics based on routine visits also showed 0.8% colonization rate; this increased dramatically to 9.2% (10 fold) in just 3 years8,9.
While colonization often precedes infection, some colonized people do not develop infection. There is a relationship between SA colonization, surgical site infection (SSI), and the ability of mupirocin to decrease both colonization and infection in some types of surgery10,11. Kluytmans et.al showed this in cardiac surgery12-14 and demonstrated cost-effectiveness as well15. A more recent cost-effective analysis corroborates this16.
In orthopedic patients, decreased SSI was initially more difficult to demonstrate17. In a recent meta-analysis, the authors calculate that randomized trials are not likely to be done because of requisite sample size. They suggest that given current data, severity and cost of infected in TJA, and the low cost/risk of mupirocin, that decolonization should be considered18. A recent study shows nasal decolonization did reduce infection in TJA patients19.
There is a growing emphasis on the idea of universal screening for all patients admitted to the hospital. Legislative initiatives have been introduced in several states. The Joint SHEA and APIC Task Force position paper states that data at this time does not support such expenditure of time and resources, but active screening should continue in at risk patients for control of resistant organisms such as MRSA20.
Both objectives were met
Figure 1: MRSA Prevalence
Data from show a
continued increase in MRSA isolates
and infections in US hospitals 2,3.
Laboratory data submitted to San
Mateo County Health Services over 10
years also shows increase in % of
MRSA from 10% to 60% (Fig.1).
OBJECTIVES
Determine by a prospective observational project the MRSA nasal
colonization rate in patients scheduled for TJA
Influence surgical practice by making available a surveillance/
decolonization program, documenting surgeon acceptance
RESULTS
Number of practices eligible - 14
Number of practices declined - 2
Acceptance - 86%
Number of practices dropping out at 3 months - 1
Number of practices completing study - 11
Number of surgeons in 11 practices - 36
Number of specimens obtained and run - 383
Number of specimens positive for MRSA – 17 ( 4.4%)
Figure 2: Specimen pick up sites
Figure 3: Cepheid - SmartCycler (RT-PCR)
SELECTED REFERENCES
1) Volturo GA, Napolitano LM, Shorr A, et al. Clinical Consensus Update: The Evolving Challenges of MRSA Infection. Analysis and Disease Management Review by the Year 2006 National Experts’ TREAHT. ClinicalWebcasts.com. May 1, 2006 [257 refs]
2) Diekema DJ, BootsMiller BJ, Vaughn TE, et al. Antimicrobial resistance trends and outbreak frequency in United States hospitals. Clin Infect Dis 2004;38(1):78-85.
3) National Nosocomial Infections Surveillance (NNIS) System Report, data summary from January 1992 through June 2004, issued October Am J Infect Control 2004;32(8):
4) Hodge, J G, Gostin L O, with the CSTE advisory committee. Public Health Practice vs. Reasearch: A Report for Public Health Practitioners Including Cases and Guidance for Making Distinctions. John Hopkins Bloomberg School of Public Health. May 24, 2004
19) Hacek DM, Robb WJ, Paule SM., et al. Staphylococcus aureus nasal decolonization in joint replacement sugurey
reduces infection. Clin Orthop Relat Res 2008
20) Weber SG, Huang SS, et al. Legislative Mandates for Use of Active Surveillance Cultures to Screen for Methicillin-
Resistant Staphylococcus aureus and Vancomycin-Resistant Enterococci: Position Statement From the Joint SHEA
and APIC Task Force. Infect Control Hosp Epidemiol 2007; 28:
References 5-18 available upon request
The authors wish to acknowledge the invaluable assistance of epidemiologist, Swati Deshpande, PhD