Abstract
Methicillin-resistant Staphylococcus aureus (MRSA), initially described in 1961, has been an increasing source of morbidity in modern health care. Resistant to all penicillins and cephalosporins, this superbug has gained increasing public and media attention as a worldwide health concern. MRSA accounts for more than half of S aureus isolates in intensive care units and causes life-threatening pneumonias, necrotizing skin infections, and wound infections.1 MRSA is now the leading pathogen in skin and soft-tissue infections, and surgical-site infections with MRSA are increasingly common.2 It is well known that MRSA infection in hospitalized individuals increases morbidity and length of hospital stay and greatly increases health care costs. Surgical infections add $5 to $10 billion to the cost of health care in the United States annually, and MRSA infections prolong hospital stays by an average of 8 days.3,4 Extra costs also include expensive antibiotic use and wound care.
Although originally confined to the immunocompromised and hospitalized, MRSA has now become commonplace in the community. Many healthy individuals are colonized, or carry the bacteria unknowingly with no signs or symptoms of infection. Colonized individuals have a fourfold increased risk to go on to develop an active MRSA infection.5 Colonization rates vary worldwide, but in the United States S aureus and MRSA colonization rates are estimated at 32.4 percent and 0.8 percent, respectively.6 MRSA colonization has a predilection for those who have been recently hospitalized but can be found in patients of any age, race, or socioeconomic status.
The anterior nares are a frequent reservoir of S aureus; therefore, patient screening is relatively quick and easy. Treatment of the anterior nares with topical mupirocin is an established and efficacious treatment for MRSA colonization.7 The objective of this study was to determine the efficacy of preoperative S aureus screening with subsequent treatment of MRSA colonized individuals on postoperative MRSA infection rates in surgical patients undergoing varied procedures in otolaryngology.
METHODS
With approval from the Evanston Northwestern Healthcare Institutional Review Board, surgical-site infection rates with MRSA were retrospectively reviewed in patients undergoing surgery from a single otolaryngology practice from August 2005 to June 2007. The infection rates of patients without preoperative screening, from August 1, 2005, to July 30, 2006, were compared with infection rates in patients undergoing preoperative screening from August 1, 2006, to June 30, 2007. The patient population included adult general otolaryngology as well as the head and neck oncology patients of a single surgeon. All patients undergoing surgery during the specified time frame were included in the study.
To screen for S aureus, a nasal swab was added to the routine preoperative testing for patients planning to undergo otolaryngology procedures from a single surgeon beginning August 1, 2006. Nasal samples were obtained by a pre-moistened rayon-tipped swab from the anterior vestibule of the nares by a nurse or patient-care technician. Real-time polymerase chain reaction was used to detect S aureus and MRSA in the nasal samples by a method previously validated.8 If positive for MRSA, the patient was treated before surgery with 2 percent mupirocin calcium ointment to the anterior nares two times a day for 5 days and a 4 percent chlorhexidine wash or shower on days 1, 3, and 5 of treatment. There were no changes in antimicrobial prophylaxis protocols throughout the study.
Surveillance for postsurgical infection was conducted and recorded as standard procedure by the hospital's infection control division. All patients with surgical-site infections were cultured for bacterial identification. A postsurgical infection was defined as a positive wound culture from a surgical site within 30 days of the operative date.
RESULTS
A total of 420 adult otolaryngology patients were included in the study. The records of 241 surgical patients were reviewed before the screening process was initiated. This population included 111 men and 130 women with an average age of 51 (range, 18–94). Forty-two patients (17%) were categorized as higher risk for MRSA infection (ie, head and neck cancer patients or patients receiving implantable devices). A total of three (1.2%) postoperative infections occurred, of which two (0.8%) were positive for MRSA. One infection occurred at a tracheostomy site in a patient in the intensive care unit with multiple comorbidities. The other surgical-site infection was in the neck of a head and neck cancer patient who had undergone an oncologic resection of the mandible.
During the time period in which screening was initiated, the records of 179 patients were reviewed. The population included 103 men and 76 women with an average age of 53 (range, 18–95), and 36 patients (20%) were categorized as higher risk for MRSA infection. Ninety-seven patients (54.2%) were preoperatively screened for S aureus, and 24 patients (24.7%) were colonized with the bacteria in the anterior nares. Of those with positive S aureus screens, two (8.3%) were identified as MRSA positive with an overall MRSA colonization rate of 2 percent. Patients positive for MRSA were treated preoperatively with mupirocin and chlorhexidine as per protocol. There were no adverse effects from the treatment protocol, and there were no MRSA postsurgical wound infections after screening was initiated.
DISCUSSION
A key principle in fighting MRSA morbidity is the prevention of the spread of MRSA, and the importance of good hygiene among health care workers is paramount. Health care workers can avoid cross-transmission of MRSA through proper gowns, gloves, and hand hygiene. Unfortunately, these preventative measures within health care settings have not been enough to control MRSA morbidity; therefore, the control of colonized individuals has become increasingly important. Mupirocin, the drug of choice in treating MRSA colonization, is safe and adverse effects are limited.7 As more prophylaxis is initiated, the likelihood of antibiotic resistance increases; however, reported mupirocin resistance is exceedingly rare when used intranasally.9 In conjunction with intranasal treatment, whole-body washes with chlorhexidine have been shown to reduce colonization rates.10 The strategy of mupirocin and chlorhexidine is currently accepted therapy for colonization.
Two different entities of MRSA exist: health care-associated MRSA and community-associated MRSA. The community-associated form usually affects younger, healthier individuals and has a propensity for skin and soft-tissue infections. The health-care associated form generally causes respiratory infections in older patients hospitalized or in care facilities.11 Despite the differences in patient populations and antibiotic resistance, surgical patients can have a postsurgical infection from either form. As MRSA infections have increased, the two forms of MRSA have become less distinct.
Prior published studies have shown the efficacy of preoperative treatment with nasal mupirocin on MRSA postoperative infection. Early reports from the intensive care setting and the orthopedic and cardiovascular surgery literature are now expanding to include other surgical patients. In a review of published studies, the eradication of MRSA with mupirocin before elective surgery lowers the MRSA surgical-site infection and is recommended.12 The institution in the present study showed a reduction in MRSA disease during admission and 30 days after hospital discharge after a screening program was initiated.13 This screening program included all hospital admissions and surgical patients with treatment of MRSA colonized individuals. In otolaryngology, the studies are limited. Miyake et al14 were able to decrease the rate of MRSA infection by the application of mupirocin to all patients with oral cancer deemed to be at high risk for MRSA. The present study is the first to examine preoperative treatment of general otolaryngology patients.
Previously, MRSA has been reported in many aspects of otolaryngology. The incidence of MRSA is as high as 9.22 percent in chronic rhinosinusitis.15 A study of MRSA in community-acquired acute rhinosinusitis identified MRSA as the pathogen in 2.7 percent of cases with risk factors of prior nasal surgery or recent antibiotic use.16 In otology, MRSA accounted for 6 percent of those with otitis externa.17 A review of patients undergoing deep-plane facelift surgery found a postoperative MRSA infection rate of 0.5 percent, half of which required readmission to the hospital. MRSA was the most common pathogen causing postsurgical infection in those patients.18
This study examined the incidence of MRSA in a general otolaryngology practice, and all types of patients were included. However, some patients undergoing surgery in an otolaryngology practice have a higher risk of postoperative MRSA infection. Risk factors for MRSA carriage include previous hospitalizations, multiple courses of antibiotics, and indwelling devices such as tracheotomies and catheters.19 Head and neck cancer patients may also be at increased risk. A significant increase in morbidity and length of hospital stay in patients with MRSA and head and neck cancer has been reported.20 The MRSA infections in our review occurred in patients at higher risk with multiple comorbidities and prior hospitalizations and included one patient with head and neck cancer.
By the identification and screening of high-risk individuals for MRSA colonization, a targeted screening program may be an effective approach for MRSA control. It has been previously suggested that a screening program is cost-effective when the MRSA infection rate is reduced by 14 percent.21 These early results suggest that screening all patients may not be cost-effective, and further studies should be performed to emphasize the effectiveness of screening high-risk populations. As previously suggested, those with head and neck cancer and those getting implantable devices such as bone-anchored hearing aids should definitely be screened for MRSA.19 In the present study, these criteria would include 17 percent to 20 percent of the patient population.
A limitation during the initiation of this screening program was that not all patients were screened preoperatively. Despite notification of primary care physicians performing preoperative visits, many did not order the screening test, especially if not affiliated with the study hospital. One recommendation to ensure appropriate screening would be to screen patients in the otolaryngology office at the time of preoperative counseling, especially those at higher risk. Although this study is limited by a small patient cohort and short time frame in which screening was conducted, with continued screening and tracking of infection rates, a better understanding of the efficacy of S aureus screening in otolaryngology can be assessed.
CONCLUSION
These early results show the potential benefit of preoperative S aureus screening in reducing the MRSA infection rate. Screening and treatment of MRSA colonized individuals preoperatively reduce infectious complications and should be considered in otolaryngology practice. Larger studies with long-term results are needed, and the benefits of screening only high-risk individuals should also be investigated. Because MRSA has the ability to adapt and evade potent antibiotics, we too as otolaryngologists need to adapt to the ever-increasing presence of antibiotic-resistant infections.