Preoperative Staphylococcus aureus Nasal Screening:

Impact on Reducing Staphylococcus aureus Associated

Surgical Site Infections

Mary Nicholson RN, BSN CICThe Christ Hospital

Cincinnati, Ohio

TCH stats

555 bed tertiary care hospital 25,840 admissions/year44 ICU beds; ADC of 36

Services: Cardiac surgery (CVS),

Orthopedic, Oncology, Neurosurgery, OB-Gyn, Renal Transplant, Medicine, and Pulmonary

Internal Medicine Residency ProgramUS News and World Report

rankings (2008)Endocrinology (29)Heart & Heart Surgery (26), Neurology & Neurosurgery (34)Respiratory Disorders (38)

Introduction

There are approximately 470,000 cardiovascular surgeries performed annually in the US.

The incidence of surgical site infections (SSI) is generally low at 1% to 8%, with an associated mortality rate of 14-47%

Complications and consequences associated with surgical site infections (SSI) are: Increased morbidity and mortality Prolonged hospitalizations Increased health care costs – sometimes greater than 2.8

times the cost of an uncomplicated postoperative CVS patients

Jakob (2000) demonstrated the frequency of wound infections in CVS patients to be 1.9% to 15% with S aureus infections varying from 12% to 36.9% of the infections.

Coronary Artery Bypass Surgery

Bypass surgery consists of grafting veins or arteries from the aorta (a major artery that carries blood from the heart to the rest of the body) to the coronary artery, bypassing areas that are blocked.

Sternal Wound Infections

Sternal/Leg Wound Infections

                             

                          

Treatment of Sternal Wounds

Medical Therapy: The use of a vacuum-

assisted closure (VAC) device, allows for either sole therapy for sternal wound closure or adjunctive therapy in preparation for muscle flap closure.

The principles of adequate wound debridement, treatment of infection, and closure of dead space still predominate as initial management decisions in treating sternal wounds.

Radical Sternectomy With significant

osteomyelitis of the sternum, fixing the sternum is impossible.

The persistent infection results in a recurring sinus tracts and infectious drainage unless the infected bone and hardware are removed.

Rectus Abdominus Flap

Rectus abdominus muscle and 8th intercostal perforator for coverage of sternal defects

Staphylococcus aureus

The most common pathogen causing SSI is Staphylococcus aureus (S. aureus).

S.aureus is endogenous to the human body with the primary site of colonization the anterior nares (Herwaldt 2003)

Weinstein (1959) noted there was a correlation between S.aureus and all types of SSI.

Kluytmans et al (1996) showed in a study that preoperative nasal carriage was the most important risk factor of surgical infections.

Studies have determined ~ 25-30% of the population may be colonized at any given time with S.aureus

Carriers of S aureus are 2-9 times more likely as non- carriers to have SSI

Jakob also demonstrated 28.1% of his CVS patients showed nasal colonization of S aureus preoperatively with 16% developing SSI, whereas the 71% patients with normal flora in their nares only 7.7% developed an SSI.

Ursy et al (2002) found in a CVS study over a 2 year period the SSI rate was 2.6% with S aureus accounting for 79.4% of that grouping

Mupirocin Usage

Perl, et. al, (2002) conducted a randomized double blinded placebo controlled trial to determine whether intranasal mupirocin reduces the rate of S. aureus infections at surgical sites and prevents other nosocomial infections

4030 patients were enrolled who underwent CVS, general surgery, neurosurgery, gynecologic procedures.

891 patients who had S aureus in their anterior nares, 444 received mupirocin and 447 placebo

Among the patients with S aureus nasal carriage 4.0% who received mupirocin had nosocomial

S.aureus infections as compared with the 7.7% who received placebo

Concluded mupirocin significantly reduced the rate of nosocomial infections due to S aureus, specifically among patients with nasal carriage of S aureus, the group expected to be at increased risk

CVS TCH STATS

At this hospital S.aureus accounted for 80% of the SSI in CVS population

During the preceding 16 month period (Jan 02 –April 03) the overall CVS SSI rate was 1.89% (18 infs/per 954 procedures performed)

MRSA non-surgical isolates occurred in ~ 11 patients each year

Study reviews found using prophylactic mupirocin ointment applied to the nares decreased the incidence of S. aureus associated nosocomial infections

2002 Quality control hospital statistics found the average cost to treat a deep sternal infection was $ 42,700.00

Study Purpose

The objective of this study was to show that, with performing prescreening nasal cultures and with both pre- and postoperative treatment with mupirocin, there would be a significant decreases in SSI in CVS patients.

Cost Impact

The cost impact of starting the project was estimated to be ~ $45,000 for approximately 900 patients $12 for the S aureus screening nasal culture ~ $38 for a 1 week supply of mupirocin

Based upon the 2002 costs of a deep sternal infection, if one infection was prevented it would pay for the cost of the project.

Culture Protocol

All patient’s nares were cultured preoperatively using the Oxoid Penicillin Binding Protein Latex agglutination test before the patient skin was prepped in the operating room. This screening test selects for S.aureus and

reports both methicillin sensitive and resistant strains

After the nasal culture was obtained, each patient received an intranasal mupirocin application to each nares

The mupirocin application was continued every 12 hours until the culture results were available. If the culture returned positive for S.

aureus, mupirocin was continued for a total of 14 doses

If the culture returned negative, mupirocin was stopped

CVS Procedures April 2003 - September 2004

687

268

61 34 14 130

100

200

300

400

500

600

700

800

CABG +/- IMA Heart valve IMA CABG + Heartvalve

Vascular Other openheart

Total

1077 patients were studied

Nasal screening results

April 2003 – September 2004

1077

855

222

30

0

250

500

750

1000

1250

Total cultured No S.aureusisolated

S aureus isolated MRSA

Approximately, 22% of the patients were identified as nasal carriers

Infections: Pre and Post Mupirocin

0

5

10

15

20

Total Infections S. aureus Infections S.aureus Deep

Pre- mupirocin Post- mupirocin

SSI Results

33% reduction in overall infections 75% decrease in S. aureus associated

infections (p < 0.006) 90% decrease in deep sternal S.aureus

infections ( p<0.0087)

Elimination of MRSA non-surgical isolates in this population and no incidences of MRSA pneumonia, UTIs or bacteremias

Cost Impact of Deep SSI Pre vs. Post Mupirocin

$513,192

$172,300

$0

$100,000

$200,000

$300,000

$400,000

$500,000

$600,000

Pre mupirocin costs Post mupirocin costs

Post mupirocin costs include the $42k start up costs

Total Joint Surgery Patients

Total Joint Prosthesis

Complications

Second to loosening of the prosthesis, infection is the most common complication of orthopedic implant procedures

Gram positive organisms such as S aureus and Coagulase negative staphylococcus are the predominant organisms in prosthetic joint infections and have occurred at a rate of 0.6 – 2.0% per 100 procedures

Infection Pathways

Introduction of microorganisms during the operative procedure, contiguous spread of post-op wound infection or colonization by hematogenous seeding

The freshly implanted biomaterial is highly susceptible to infection – colonization by even small numbers of bacteria can lead to joint sepsis

During the early post-op period, when superficial infections can develop, the fascial layers have not healed and the deep periprosthetic tissue is not protected by usual physical barriers

Any factor that delays wound healing increases the risk such as: ischemic necrosis, hematoma, wound sepsis or suture abscesses

Treatment Options

Joint irrigation with antibiotics Antibiotic therapy without removal of prosthesis 2 stage implant exchange

Prosthesis removal (infected bone, soft tissue and joint linings- called a synovectomy)

Followed by irrigation and implantation of an antibiotic implanted spacer

Treated with 6-8 week course of antibiotics Once infection is cleared, joint is re-implanted

Arthrodesis- the surgical immobilization of a joint until the bone has healed

Antibiotic Impregnated Joint

TCH Ortho Stats

At TCH over 500 total joint surgeries are performed each year

The associated SSI rate had averaged 0.86% per 100 procedures over the previous 2 year period. S. aureus had accounted for 50% of the SSIs SSI rate 2002 = 1.2% SSI rate 2003 = 0.6%

Hospital Stats

In 2004, there was an increase in total joint SSIs with an associated rate of 1.49% (8/453).

Upon further investigation 5/8 of the SSI were caused by S.aureus (with

3/5 isolates were MRSA) The patients and OR team underwent nasal

cultures to rule out S. aureus nasal colonization 4 patients and 1 OR team member was

identified as S. aureus nasal carriers

All S. aureus isolates were sent to the Ohio Department of Health for DNA pulse field gel electrophoresis typing (PFGE).

This included 5 patients and 1 OR team member’s nasal isolate Six (6) different strains of S. aureus were

identified None of the strains were linked

epidemiologically One patient’s daughter was also

hospitalized with MRSA sepsis and both patient and daughter shared the same strain of MRSA

Protocol

Beginning in December 2004, all total joint patients when reporting for Pre Admission Testing (PAT) Nasal cultures were obtained to rule out S. aureus Cultures are sent to LabOne of Ohio using the

Oxoid penicillin binding protein Latex agglutination test

Culture results would generally be available within 48 hours and before patient was admitted to hospital for surgery

In those cases where cultures had not been collected PTA, SDS are to send a nasal screening culture and begin intranasal mupirocin before surgery

Treatment of Carriers

S.aureus sensitive carriers To receive intranasal mupirocin BID for 7 days IV cephazolin or clindamycin is to be

administered as the pre-operative surgical antimicrobial

Mupirocin is to be continued during hospitalization if not completed pre-operatively

Follow-up culture to be obtained in surgeon’s office

Treatment of Carriers

Methicillin resistant carriers To receive intranasal mupirocin BID for 7 days IV vancomycin is administered as the pre-

operative surgical antimicrobial Patients are instructed to shower with CHG soap Patients are placed into Contact isolation upon

admission to the hospital and continued until culture negative

Mupirocin is continued during hospitalization if not completed pre-operatively

Follow-up culture is obtained in surgeon office

Total Joint ProceduresDec 04 - Dec 2005

Figure 1

7

187

229

0

50

100

150

200

250

THR TKR Shoulder

total

Nasal Culture Results (Dec 04 – Dec 05)

435

316

99

20

050

100150200250300350400450500

Total cultured No Staph aureus S. aureus sensitive MRSA

27% of patients were identified as S aureus carriers at the time of PAT

Findings

27.3% (119/435) of total joint procedure patients were identified as S aureus nasal carriers at the time of pre-admission testing. 16.8% (20/119) of S aureus nasal isolates were MRSA strains.

Zero (0) deep infections occurred during the post mupirocin treatment study period. There was one superficial SSI. There were no deep infections associated with S. aureus.

The SSI rate post mupirocin, was 0.19% (1 infection / 534 procedures). There was an 82% reduction in overall SSIs in historical group (16/1467) to the treated group (p < 0.03).

Infections Pre-mupirocin and Post-mupirocin

16

11

5

9

1 0 1 1

0

4

8

12

16

20

Total infections Deep infections Superficial Total S.aureus

Pre mupirocin Post mupirocin

Pre-op nasal screening results

CVS screening results thru June 08

3933

3081

697

148

0

500

1000

1500

2000

2500

3000

3500

4000

4500

Total no SAS SAS MRSA

Total Joint screening results

Dec 04- June 08

2614

1973

523

980

500

1000

1500

2000

2500

3000

Total No SAS SAS MRSA

Dec 04- June 08

Orthopedic spinal procedures

Jan 07 - June 08

1069

220

36

813

-100

100

300

500

700

900

1100

1300

total No SAS SAS MRSA

Jan 07 - June 08

Pre-op nasal screening impact on SSI

Service Total screened Reductions in SA/MRSA SSI

CVS 3933 90%

Total Joints 2614 75%

Spinal 1069 70%

Application of project and future directions

Pre-operative nasal screening may be applied to other services if S. aureus is a frequent source of SSIs

To be successful, efforts should be coordinated with surgeon offices, microbiology labs and hospitals

Obtaining a culture pre-operatively, eliminates the need to prophylactically treat all patients with a 7 day course of mupirocin; and should reduce the risks of drug resistance

Targeting vancomycin usage for MRSA carriers should minimize the risks of drug resistance

MRSA stats at TCH

MRSA surveillance at TCH

MRSA CASES TRACKED/Healthcare Associated

362 405488 503

639

899 8911039

28 22 25 30 21 21 21 36

0

200

400

600

800

1000

1200

2000 2001 2002 2003 2004 2005 2006 2007

YEAR

# C

ASES

Admissions Nosoc Inf

Patients identified with MRSA – are placed in Contact isolation and records are “flagged”; so that when readmitted - placed in isolation until cultures return negative

Recommendation from ICC

Continue pre-operative nasal screening for SAS/MRSA colonization

Expand the pre-op screening to include patients with other implantable devices (e.g. vascular grafts, ICD, etc).

Support the initiation of a surveillance study in MICU to determine baseline prevalence rate of MRSA nasal carriage (medical residents)

Continue to place all MRSA patients in Contact isolation until follow-up cultures return negative

Do not recommend MRSA hospital wide surveillance at this time.

Awards and Publication

 

2004 Sodexho Health Care Services : Honorable Mention: Spirit of Excellence Award for Quality

Nicholson, MR and Huesman LA. Controlling the usage of intranasal mupirocin does impact the rate of Staphylococcus aureus deep sternal wound infections in cardiac surgery patients. Am J Infect Control 2006; 34(1):44-48.

Midwest Nursing Research Society Annual Meeting, Milwaukee April 2006 Poster presentation: Limiting the Usage of Intranasal Mupirocin Does Impact the Rate of Staphylococcus aureus Deep Sternal Wound Infections

APIC Blue Ribbon Abstract Award 2006 – Tampa, June 2006: Poster Presentation: Pre-operative Staphylococcus aureus Nasal Screening does Reduce Total Joint Surgical Site Infections

American College of of Orthopedic Surgeons – Poster presentation- February 2007: Screening for S. aureus does Reduce Total joint SSI.

Anthem’s Hospital Quality Meritorious Award March 2007

Poster and Oral presentations at National Orthopedic Nursing Association May 2007 and 2008.

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