| Abstract: | BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) infections are increasingly being encountered and pose an increasing burden to the health care system in Canada.OBJECTIVE: To elucidate and characterize the factors influencing the current MRSA treatment patterns in patients with skin and soft tissue infections (SSTIs) before linezolid became available on the Canadian market.METHODS: A retrospective study collected demographic, treatment and resource use data on patients hospitalized at one of three geographically distinct tertiary care facilities, where MRSA SSTI treatment was initiated with intravenous (IV) vancomycin. Analysis of opportunities for IV-to-oral switch therapy was based on eligibility criteria.RESULTS: Of 89 patients identified over a 43-month period, the mean (±SD) durations of anti-infective treatment and hospitalization were 22.4±21 days and 28.9±20.8 days, respectively. An infected surgical wound was most common, representing 62.9% of infections. The mean duration of vancomycin treatment was 19.5 days and the mean number of 1 g doses received was 29.0±32.9. The majority of patients (55.1%) initiated vancomycin therapy a mean of 5.4±8.9 days after confirmation of MRSA. Of the 70% of patients meeting criteria for IV-to-oral switch therapy, only 10% received oral treatment. The most common reason cited for not switching was lack of an effective oral alternative. Analysis of switch therapy criteria found that IV treatment continued for a mean of 13 days despite the appropriateness of the oral route.CONCLUSIONS: Considerable variation exists in treatment patterns for MRSA infections. Improvements in the initiation of therapy and the use of IV-to-oral switch therapy may improve care and reduce the duration of hospitalization for MRSA SSTIs.Key Words: Methicillin-resistant Staphylococcus aureus, Switch therapy, Treatment patterns, VancomycinAntibiotic resistance is of growing importance to health care systems worldwide, and Canada is no exception (1). Due to the serious nature of emerging antibiotic-resistant pathogens and the limited therapeutic options available to treat them, infections caused by these organisms may be associated with increased morbidity and mortality (2-4) compared with those caused by drug-sensitive organisms, and pose an increasing economic burden to health care systems (5). Among the resistant organisms, methicillin-resistant Staphylococcus aureus (MRSA) is increasingly being encountered in Canadian health care facilities (1). Although the first report of an MRSA isolate in Canada was in 1981 (6), only occasional reports followed. In 1995, the Canadian Nosocomial Infection Surveillance Program (CNISP) began following the incidence of MRSA prospectively and reported an increase from 1% of all S aureus isolates in 1995 to 8.1% in 2000 in the health care facilities participating in the CNISP (7). The majority of the increase in MRSA cases has occurred in Ontario and Quebec, followed by British Columbia (7). Although MRSA was initially a hospital-acquired pathogen, it has also recently been recognized as a community-acquired organism (8-11) in Canada, particularly among First Nations peoples.Because MRSA is often resistant to multiple antibiotics, treatment options may be limited. The usual treatment for serious infections caused by MRSA is vancomycin (12). This antibiotic is available only in the intravenous (IV) form for treatment of these types of infections, and it has the potential for greater toxicity and may be less effective than conventional therapy for infections caused by susceptible staphylococci (5). Furthermore, certain organisms have exhibited increasing rates of resistance to vancomycin, which may limit its usefulness. A Passive Reporting Network established within the CNISP identified 1315 cases of vancomycin-resistant enterococci throughout Canada between 1994 and 1998 (13). In addition, cases of vancomycin-intermediate strains of S aureus have been reported recently in Japan, Europe, Hong Kong and the United States (14-16), although no cases have yet been confirmed in Canada.Other than intravenous vancomycin, several oral MRSA treatment alternatives are available including trimethoprim-sulfamethoxazole, alone or in combination with rifampin; doxycycline; fusidic acid in combination with rifampin; or fluoroquinolones alone or in combination with rifampin, dependent on the susceptibility of the strain. Five years of MRSA surveillance in several hospitals across Canada found resistance rates to ciprofloxacin, trimethoprim-sulfamethoxazole, rifampin and fusidic acid to be 89%, 56%, 3% and 3%, respectively (17). Linezolid, an antibacterial agent available in both IV and oral forms, was approved for use in Canada following the completion of the present study and represents a new option for the treatment of Gram-positive infections, including those caused by MRSA.Although vancomycin IV has been identified as the current drug of choice for the treatment of MRSA infections, very little is known regarding the real-life practice patterns of treating physicians across Canada. In an effort to gain an understanding of how MRSA infections are currently being treated, we undertook a retrospective study of vancomycin treatment patterns for MRSA infections in geographically distinct regions across Canada, focusing on infections of the skin and soft tissue (SSTIs). Emphasis was placed on determining MRSA treatment characteristics including antimicrobial use, duration of therapy, length of hospital stay (LOS) and use of home IV care services. In addition, an analysis of IV-to-oral switch therapy patterns was conducted to understand the current level of acceptance of the practice, its potential benefits and the barriers to switch therapy in MRSA SSTIs. |
