Predicting methicillin resistance and the effect of inadequate empiric therapy on survival in patients with Staphylococcus aureus bacteremia

BACKGROUND: The restriction of vancomycin hydrochloride use is recommended as a measure to decrease the emergence of vancomycin resistance in gram-positive organisms; however, vancomycin also is the treatment of choice for methicillin-resistant Staphylococcus aureus (MRSA) infections. If vancomycin use is restricted to patients with documented infections due to methicillin-resistant organisms, then patients with MRSA infections may not initially receive vancomycin. This study was performed to determine factors that predict MRSA bacteremia and if ineffective empiric antibiotic therapy increased the risk of death in patients with S aureus bacteremia. METHODS: We conducted a retrospective cohort study of all patients with clinically significant S aureus bacteremia (132 episodes in 128 patients) diagnosed between October 1, 1995, and January 1, 1998, at an urban acute care Veterans Affairs medical center (approximately 200 acute care beds) in Baltimore, Md. During the study period, vancomycin was a restricted antibiotic. Empiric use had to be approved by an attending physician specializing in infectious diseases. RESULTS: Compared with patients who had methicillin-sensitive S aureus bacteremia, patients with MRSA bacteremia were significantly older (70 vs 58 years; P<.01), more likely to have a history of MRSA (47% vs 6%; P<.01) and a nosocomial infection (76% vs 50%; P<.01), and less likely to use injection drugs (8% vs 32%; P<.01). In addition, compared with patients who had methicillin-sensitive S aureus bacteremia, patients with MRSA bacteremia were significantly less likely (45% vs 98%; P<.01) to receive effective antibiotic therapy during the first 48 hours of hospitalization. However, the risk of death due to ineffective empiric therapy was less than 1 (relative risk, 0.82; 95% confidence interval, 0.36-1.88) and did not change significantly when adjusted for age, occurrence of sepsis, or nosocomial infection. CONCLUSIONS: The results of this study support the safety of the restriction of vancomycin use in patients with clinically significant S aureus bacteremia. However, patients with a history of MRSA are more likely to have future MRSA infections and should receive empiric therapy using vancomycin for possible S aureus infections, particularly for nosocomial infections.     

Successful salvage of peritoneal catheter in unresolved methicillin-resistant staphylococcus aureus peritonitis by combination treatment with daptomycin and rifampin

Peritoneal dialysis patients are at an increased risk of Gram-positive organism infections because of disrupted skin barrier function, presence of a peritoneal catheter, and a deficient immunological system. In particular, the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections is clinically challenging. Herein, we present a case of MRSA peritonitis that showed no response to a 14-day treatment with intraperitoneal vancomycin. To overcome unresponsiveness to vancomycin, we shifted the regimen to intraperitoneal daptomycin (given every 6 h through manual peritoneal dialysate exchanges) and oral rifampin (300 mg twice daily). The peritonitis resolved without sequelae or relapse. We suggest daptomycin and rifampin as an alternative combination therapy for MRSA infections that may otherwise remain unresolved.     

Enteral vancomycin to control methicillin-resistant Staphylococcus aureus outbreak in mechanically ventilated patients

BACKGROUND: Screening for and treating gut carriage of methicillin-resistant Staphylococcus aureus (MRSA) may control transmission and subsequent endemicity of MRSA. OBJECTIVE: Enteral vancomycin was evaluated as a measure to control an outbreak of MRSA infection in the intensive care unit (ICU). METHODS: During the 8-month study of sequential design, 176 patients were admitted, 65 (37%) of whom required a minimum of 3 days of ventilation. Forty-four patients were studied in the first 5 months, during which traditional measures were reinforced (control group). During the following 3 months, 13 of 21 patients developed MRSA carriage and received 2 g/day of enteral vancomycin, with high standards of hygiene maintained (treatment group). RESULTS: Thirty-three MRSA infections occurred in 22 patients (50%) in the control group, whereas 2 patients (9.5%) had 2 MRSA infections in the treatment group (P <.05 for carriage, infection rates, and episodes). Of the 33 MRSA infections in the control group, 27 were due to MRSA acquired in the ICU, whereas the 2 infections in the treatment group were primary endogenous (ie, caused by MRSA present in the patient's admission flora). The probability of developing an MRSA infection was reduced in patients receiving enteral vancomycin compared with patients in the control group (odds ratio, 0.37; 95% CI, 0.24-0.58). Enteral vancomycin significantly reduced the level of MRSA carriage; the mean carriage index was 1.01 in the control group versus 0.58 in the test group (P <.05). Neither vancomycin-resistant enterococci nor vancomycin-intermediate Staphylococcus aureus were isolated from either surveillance or diagnostic samples. CONCLUSIONS: The eradication of MRSA gut carriage by enteral vancomycin in a small subset of ICU patients was effective in the control of an MRSA outbreak.     

Methicillin-resistant Staphylococcus aureus prosthetic aortic valve endocarditis with paravalvular abscess treated with daptomycin

Prosthetic valves have been used extensively for severe cardiac valvular dysfunction for the past 3 decades. Prosthetic cardiac valves may be infected with organisms causing bacteremia, particularly gram-positive cocci. Staphylococcus epidermidis (coagulase negative staphylococci) and Staphylococcus aureus , both methicillin-susceptible S. aureus and methicillin-resistant S. aureus (MRSA) strains, are the most frequent pathogens causing prosthetic valve endocarditis (PVE). Vancomycin has been the cornerstone of therapy for serious MRSA infections including bacteremia and endocarditis. Clinicians have noted that MRSA bacteremias treated with vancomycin often fail to clear even with prolonged therapy. Persistent or prolonged MRSA bacteremia unresponsive to vancomycin therapy has led to the treatment of these infections by other agents, that is, quinupristin, dalfopristin, linezolid, or daptomycin. These antibiotics have been found particularly useful in treating MRSA bacteremias unresponsive to vancomycin therapy. We report a case of a patient who presented with MRSA PVE complicated by perivalvular aortic abscess with persistent MRSA bacteremia unresponsive to vancomycin therapy. The patient's MRSA bacteremia was cleared with daptomycin therapy (6 mg/kg/d). Because the patient refused surgery, daptomycin therapy was continued in hopes of curing the endocarditis and sterilizing the perivalvular aortic abscess. Transesophageal echocardiogram revealed a decrease in abscess in the aortic perivalvular abscess after 1 week of daptomycin therapy. The patient made an uneventful recovery. The cure of PVE and perivalvular abscesses usually requires removal of the prosthetic device and abscess drainage. In this case, in which surgery was not an option, medical therapy of PVE and a decrease in size of the aortic perivalvular abscess were accomplished with daptomycin therapy. Daptomycin is an alternative to vancomycin therapy in patients with prolonged or persistent MRSA bacteremia secondary to endocarditis or abscess.     

Methicillin-resistant staphylococci and their treatment in the intensive care unit

Methicillin resistance in Staphylococcus aureus (MRSA) and the coagulase-negative staphylococci (MRCNS) is widespread and continues to increase in prevalence, particularly in the health care setting. The clinical significance of methicillin resistance for patients with staphylococcal infections is not clear: studies in patients with bacteremia, pneumonia, and mediastinitis show a higher mortality with MRSA infection compared to methicillin-sensitive Staphylococcus aureus (MSSA) infection, though this may be due to underlying patient, pharmacodynamic, or microbiological differences. For serious methicillin-resistant staphylococcal infections, vancomycin-based regimens are preferred. Treatment alternatives for patients with severe methicillin-resistant infections who are unable to tolerate vancomycin include linezolid and quinupristin/dalfopristin; these agents should be considered second-line options, given the relative lack of clinical experience and the nonsignificant but consistent trends toward worse outcomes in bacteremia and pneumonia with these agents compared to vancomycin. For less severe infections, treatment options also include trimethoprim-sulfamethoxazole, or fluoroquinolones in combination with rifampin.     

Vancomycin for surgical prophylaxis?

The increasing prevalence of methicillin-resistant Staphylococcus aureus (MRSA) has resulted in a reevaluation of the role of vancomycin for surgical prophylaxis. Two systematic reviews of randomized control studies have concluded that cephalosporins are as effective as vancomycin for the prevention of surgical site infections (SSIs). However, most of these studies were conducted more than 10 years ago and cannot be generalized to the current rates of MRSA. Several time-series analyses have recently evaluated the effectiveness of vancomycin for surgical prophylaxis in institutions with a high prevalence of MRSA. Decision analysis models have also been used to estimate thresholds of MRSA prevalence for which vancomycin would minimize the incidence and cost of SSIs. Combination therapy and the emergence of resistant pathogens following vancomycin prophylaxis are reviewed. Vancomycin is not recommended for routine use in surgical prophylaxis but may be considered as a component of a MRSA prevention bundle for SSIs in selective circumstances.     

The costs and consequences of methicillin-resistant Staphylococcus aureus infection treatments in Canada.

BACKGROUND: A multinational randomized controlled trial has shown a trend toward early discharge of patients taking oral linezolid versus intravenous vancomycin (IV) in the treatment of methicillinresistant Staphylococcus aureus (MRSA) infections. Infection treatments resulting in shorter hospitalization durations are associated with cost savings from the hospital perspective. OBJECTIVE: To determine whether similar economic advantages are associated with oral linezolid, the costs and consequences of linezolid use following vancomycin IV versus the existing practice in the treatment of infections caused by MRSA were compared. METHODS: The charts of all patients admitted to one of three tertiary care teaching hospitals between January 1, 1997 and August 31, 2000 and treated with vancomycin IV for an active MRSA infection (skin and soft tissue only) were reviewed. Based on the vancomycin IV chart review data set and a simulated linezolid data set, the clinical consequences and the associated costs of MRSA treatment with vancomycin IV, and oral and IV forms of linezolid were quantified and compared within the framework of a cost-consequence analysis. RESULTS: Patients treated with oral and IV forms of linezolid compared with the existing practice had a shorter length of stay and required fewer home IV care services, which resulted in a cost savings of $750 (2001 values) to the Canadian health care perspective. CONCLUSIONS: The estimated cost savings associated with linezolid use not only offset the higher acquisition cost of the anti-infective, but may be substantial to health care systems across Canada, especially as the incidence of MRSA continues to rise.     

Susceptibility to vancomycin of methicillin-resistant Staphylococcus aureus isolated in a university hospital in Japan

Intravenous vancomycin was approved in 1991 in Japan and has been widely used for treatment of infections caused by methicillin-resistant Staphylococcus aureus (MRSA). Consequently, ever since the initial discovery of vancomycin intermediate-resistant S. aureus in Japan, the vancomycin resistance of this organism has been a great concern in clinical settings. We investigated whether vancomycin resistance had emerged in MRSA isolated in our hospital since the approval of the use of intravenous vancomycin. Vancomycin susceptibility was evaluated on the basis of minimum inhibitory concentrations determined by the agar dilution method and a heterogeneous resistance examination. The median minimum inhibitory concentration of the 69 MRSA strains isolated in 1988 and the 74 isolated in 1998 was 0.75 microgram/ml and 1.0 microgram/ml, respectively (p < 0.001), however, all of the strains were classified in the susceptible group. None of them was an MRSA heterogeneously resistant to vancomycin (hetero-VRSA), which has been defined as a strain having a 1/10(6) or greater heterogeneously resistant subpopulation to vancomycin. In another set of investigations, no hetero-VRSA were found among 12 other MRSA strains isolated after intravenous administration of vancomycin for 14 or more days (range: 14 to 77 days). We conclude that while the use of intravenous vancomycin may have slightly lowered the vancomycin susceptibility of MRSA in our hospital, the decrease in so small that it may not be significant clinically. In addition, no hetero-VRSA were found in our hospial.     

Successful treatment of right-sided native valve methicillin-resistant Staphylococcus aureus endocarditis and septicaemia with teicoplanin and rifampicin: a case report

Vancomycin is the drug of choice in the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infection. However, the presence of certain clinical complications like renal failure alters vancomycin pharmacokinetics, leading to drug accumulation and toxicity. This highlights the need to identify an effective substitute for treating MRSA infections when vancomycin cannot be used. We report the case of a 57-y-old Indian male diagnosed with tricuspid valve endocarditis with septicaemia and a right upper lobe cavity caused by MRSA. The patient also presented with renal failure, which precluded the use of vancomycin for treatment. A 6-week regimen of teicoplanin and rifampicin was used instead, and the infection was successfully treated. This case report provides evidence of the effectiveness of teicoplanin and rifampicin in the treatment of MRSA bacteraemia in situations where the use of vancomycin is contraindicated.     

Synercid plus vancomycin for the treatment of severe methicillin-resistant Staphylococcus aureus and coagulase-negative staphylococci infections: evaluation of 5 cases

Synercid (quinupristin/dalfopristin), the first semi-synthetic injectable streptogramin, is a promising alternative to glycopeptides against many Gram-positive multiresistant bacteria. Vancomycin is still considered an effective agent for the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections but therapeutic failures with glycopeptides have been observed, even for the treatment of infections caused by S. aureus strains sensitive to vancomycin. Synercid, in combination with a glycopeptide, may address this problem without causing significant side effects due to the different toxicity patterns of the 2 antimicrobials. This study reports our experience with the combination of Synercid and vancomycin in 5 patients with severe infection caused by MRSA or methicillin-resistant coagulase-negative Staphylococcus.     

Diagnosis and management of Staphylococcus aureus infections of the skin and soft tissue

Infections involving the skin and soft tissue are common and range from superficial, localized and sometimes self-limiting infections to deep, rapidly spreading and potentially life-threatening infections. Skin infections caused by Staphylococcus aureus include primary pyodermas, while those involving the soft tissues include cellulitis and pyomyositis. Surgical site infections and infections in intravenous drug users are also commonly caused by S. aureus. The severity of the infection determines the choice of treatment. There are few studies that have critically appraised the use of antibiotics in skin and soft tissue infections, and most guidelines are based on expert opinion. The beta-lactam group of antibiotics are the mainstay of treatment for methicillin-susceptible S. aureus infections. For methicillin-resistant S. aureus (MRSA) infections, both with community-acquired and hospital-acquired strains--which are becoming an increasing problem--the antibiotic choice is determined by local susceptibility patterns. Macrolides, clindamycin and cotrimoxazole are options for community-acquired MRSA, while vancomycin is reserved for treatment of infections caused by multiresistant MRSA strains and for patients with suspected endocarditis or severe sepsis. Although a number of the newer antibiotics such as linezolid and quinopristin/dalfopristin have been shown to have good activity against MRSA, these agents should only be used with specialist advice.     

Vancomycin-resistant Staphylococcus aureus: a new model of antibiotic resistance

Vancomycin has been the most reliable therapeutic agent against infections caused by meticillin-resistant Staphylococcus aureus (MRSA). However, in 1996 the first MRSA to acquire resistance to vancomycin, was isolated from a Japanese patient. The patient had contracted a post-operative wound infection that was refractory to long-term vancomycin therapy. Subsequent isolation of several vancomycin resistant S. aureus (VRSA) strains from USA, France, Korea, South Africa, and Brazil has confirmed that emergence of vancomycin resistance in S aureus is a global issue. A certain group of S. aureus, designated hetero-VRSA, frequently generate VRSA upon exposure to vancomycin, and are associated with infections that are potentially refractory to vancomycin therapy. Presence of hetero-VRSA may be an important indicator of the insidious decline of the clinical effectiveness of vancomycin in the hospitals. Vancomycin resistance is acquired by mutation and thickening of cell wall due to accumulation of excess amounts of peptidoglycan. This seems to be a common resistance mechanism for all VRSA strains isolated in the world so far.     

Prevention of MRSA pneumonia by oral vancomycin decontamination: a randomised trial.

This study was undertaken to assess whether oropharyngeal vancomycin may control oropharyngeal carriage and lower airway infection due to methicillin-resistant Staphylococcus aureus (MRSA) acquired in the intensive care unit (ICU). Secondary endpoints were the emergence of vancomycin-resistant enterococci, vancomycin-intermediate S. aureus and vancomycin consumption. A total of 84 patients, admitted to a medical/surgical ICU and mechanically ventilated for >72 h, were randomly assigned to control (n=42) or test (n=42) group. Both groups received the protocol of selective decontamination of the digestive tract, including polymyxin E, tobramycin and amphotericin B. Patients in the test group received 0.5 g of a 4% vancomycin gel at 6-h intervals in the oropharynx. Lower airway infections due to MRSA acquired on the ICU were reduced in the test group, as was oropharyngeal carriage. Neither vancomycin-resistant enterococci nor vancomycin-intermediate S. aureus were isolated from either surveillance or diagnostic samples during the study period. The vancomycin costs were lower in the test group. This study demonstrates that oropharyngeal vancomycin, which controls intensive care unit-acquired lower airway infections and secondary carriage due to methicillin-resistant Staphylococcus aureus, is cost-effective and safe in terms of vancomycin-resistant enterococci and vancomycin-intermediate Staphylococcus aureus.     

Daptomycin and vancomycin non-susceptible methicillin-resistant Staphylococcus aureus clonal lineages from bloodstream infection in a Brazilian teaching hospital

IntroductionThis study aimed to characterize Staphylococcus aureus isolates from bloodstream infections in patients attending a teaching hospital, between 2011 and 2015.MethodsThe minimum inhibitory concentration for daptomycin, linezolid, oxacillin, teicoplanin, vancomycin, and trimethoprim/sulfamethoxazole was accessed by broth microdilution. SCCmec type and clonal profile were determined by molecular tests. Vancomycin heteroresistance was evaluated using screening tests and by population analysis profile/area under the curve.ResultsAmong 200 S. aureus isolates, 55 (27.5%) were MRSA, carrying SCCmec II (45.5%) or IV (54.5%). The most frequent MRSA lineages were USA100 (ST5-II) (45.5%) and USA800 (ST5-IV) (30.9%). Six isolates were confirmed as vancomycin heteroresistant, showing area under the curve ratio 1.1, 1.2 or 1.3 (four USA100, one USA800 and one USA1100 isolates).ConclusionsDaptomycin and vancomycin non-susceptible MRSA clonal lineages were found in bloodstream infections over five years, highlighting the importance of continuous surveillance of multiresistant bacteria in hospitals.     

High-dose vancomycin therapy for methicillin-resistant Staphylococcus aureus infections: efficacy and toxicity

BACKGROUND: Vancomycin hydrochloride treatment failure for infections caused by susceptible methicillin-resistant Staphylococcus aureus (MRSA) strains with high minimum inhibitory concentration (MIC) has prompted recent guidelines to recommend a higher vancomycin target trough of 15 to 20 microg/mL. METHODS: A prospective cohort study of adult patients infected with MRSA was performed to determine the distribution of vancomycin MIC and treatment outcomes with vancomycin doses targeting an unbound trough of at least 4 times the MIC. The microbiology laboratory computer records were used to identify all patients from whom MRSA was isolated from August 1, 2004, through June 30, 2005. Primary outcome measures were clinical response, mortality, and nephrotoxicity. Patients were placed into subgroups based on target trough attainment and high vs low vancomycin MIC (>/=2 vs <2 microg/mL) for efficacy and high vs low trough (>/=15 vs <15 microg/mL) for nephrotoxicity analyses. RESULTS: Of the 95 patients in the study, 51 (54%) were infected with high-MIC strains and had pneumonia (77%) and/or bacteremia. An initial response rate of 74% was achieved if the target trough was attained irrespective of MIC. However, despite achieving the target trough, the high-MIC group had lower end-of-treatment responses (24/39 [62%] vs 34/40 [85%]; P = .02) and higher infection-related mortality (11/51 [24%] vs 4/44 [10%]; P=.16) compared with the low-MIC group. High MIC (P = .03) and Acute Physiology and Chronic Health Evaluation II score (P = .009) were independent predictors of poor response in multivariate analysis. Nephrotoxicity occurred only in the high-trough group (11/63 [12%]), significantly predicted by concomitant therapy with other nephrotoxic agents. CONCLUSIONS: High prevalence of clinical MRSA strains with elevated vancomycin MIC (2 microg/mL) requires aggressive empirical vancomycin dosing to achieve a trough greater than 15 microg/mL. Combination or alternative therapy should be considered for invasive infections caused by these strains.     

Clinical utility of negative methicillin-resistant Staphylococcus aureus (MRSA) nasal surveillance swabs in skin and skin structure infections

BackgroundNegative methicillin-resistant Staphylococcus aureus (MRSA) nasal swabs have a high negative predictive value of approximately 99% in respiratory infections. There is, however, a lack of data evaluating its use beyond respiratory infections.MethodsWe conducted a retrospective analysis to determine the clinical utility of MRSA swabs for identifying MRSA-associated skin and skin structure infections (SSSIs) and the potential effects on antimicrobial stewardship efforts. Baseline characteristics, culture data, and antibiotic data were collected to determine the difference in duration of vancomycin therapy. Positive predictive value, negative predictive value, sensitivity, and specificity were secondary outcomes.ResultsA total of 473 patients were included, of which 156 patients had a positive MRSA nasal swab and 317 patients had a negative swab. The median duration of vancomycin was 4 days in the positive group and 3 days in the negative group (P = .01). The positive predictive value and negative predictive value were 22.4% and 97.5%. The sensitivity and specificity were 81.4% and 71.9%.ConclusionPatients with a negative MRSA nasal swab received approximately 1 day less of vancomycin, which represented a decrease in drug administered. The negative predictive value for SSSIs is promising, showing potential for the role of MRSA nasal swabs in de-escalating therapy.     

A retrospective analysis of practice patterns in the treatment of methicillin-resistant Staphylococcus aureus skin and soft tissue infections at three Canadian tertiary care centres.

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.     

Purulent pericarditis due to methicillin-resistant Staphylococcus aureus. A case report.

Purulent pericarditis is an infrequent complication of infections originating in another body location. Symptoms and signs are often absent; a high index of awareness is required for its diagnosis. A patient recovering from extensive necrotic-hemorrhagic pancreatitis presented with tamponade due to methicillin-resistant Staphylococcus aureus (MRSA) purulent pericarditis, further complicated by MRSA endocarditis. Treatment included pericardectomy, IV vancomycin and teicoplanin.     

Spread of Staphylococcus aureus in hospitals: causes and prevention

Methicillin-resistant Staphylococcus aureus (MRSA) has become a major nosocomial pathogen in many hospitals worldwide. Even more alarming, MRSA strains that are vancomycin intermediate-susceptible are isolated with increasing frequency, making therapy for staphylococcal infections even more difficult and prevention more important than ever. Spread of S. aureus in hospitals and infection control measures are reviewed. The major sources of S. aureus in hospitals are septic lesions and carriage sites of patients and personnel. Carriage often precedes infection. The anterior nares are the most consistent carriage site, followed by the perineal area. Skin contamination and aerial dissemination vary markedly between carriers and are most pronounced for combined nasal and perineal carriers. The principal mode of transmission is via transiently contaminated hands of hospital personnel. Airborne transmission seems important in the acquisition of nasal carriage. Infection control strategies include screening and isolation of newly admitted patients suspected of carrying MRSA or S. aureus with intermediáte resistance to vancomycin, implementation of an infection control program to prevent transmission of resistant strains between patients and hospital personnel, and institution of a proper antibiotic policy to minimize antibiotic resistance development. MRSA carriers should be treated with intranasal antibiotics, e.g. mupirocin, and skin disinfectants to eliminate carriage. Education of hospital personnel is essential. Improved knowledge about the best ways to ensure favourable infection control practices is needed. Active intervention against the spread of MRSA is important.     

Optimizing therapy for MRSA pneumonia

With its remarkable armamentarium of resistance and virulence factors, Staphylococcus aureus has emerged as a dominant pathogen causing pneumonia of all classifications. Rates of methicillin resistance are increasing as clinicians struggle to find ways to prevent the acquisition of methicillin-resistant Staphylococcus aureus (MRSA) and to effectively treat MRSA pneumonia. Community-associated MRSA has been identified as an important subset of MRSA with unique characteristics. Vancomycin remains a recommended first-line therapy for MRSA pneumonia, but resistance and therapeutic failures with vancomycin are being increasingly reported. Factors associated with vancomycin success or failure have been identified, including the genetics of the MRSA isolate, vancomycin lung penetration, minimum inhibitory concentration, and pharmacokinetic and pharmacodynamic variables. Retrospective analyses suggest that linezolid may provide improved outcomes compared with vancomycin for MRSA pneumonia, but validation in a prospective trial is currently lacking. Other treatment options are limited, but new prospects are being investigated. This paper reviews the epidemiology and pharmacotherapy of MRSA pneumonia.