Since the early 2000s, multiple studies have reported a dramatic rise in SSTI incidence across outpatient, emergency department (ED), and inpatient hospital settings.1,4,5 Between 1997 and 2005, the annual incidence in ambulatory visits for purulent SSTI increased from 4.6 million to 9.6 million.5 In the United States (US), this dramatic rise in SSTI incidence was largely driven by the epidemic of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) USA300 clone.1
Using nationally representative data, a recent study found a dramatic rise in ambulatory visit incidence (to EDs and physician offices) for purulent SSTIs, peaking in 2010–2013, followed by a plateau in recent years. The total annual number of visits for purulent SSTI-related visits to ambulatory physicians in the US increased from 5.4 million in 2000 to a peak of 11.35 million in 2013 and declined to 8.4 million in 2015. Moreover, by practice setting, in recent years the decline in overall SSTI visits was driven by a large reduction in office visits, while ED visits remained unchanged. Over the study period, prescriptions for antibiotics recommended for methicillin-resistant S. aureus (MRSA) increased, while β-lactam monotherapy prescriptions decreased.4
While many patients with SSTI have no identifiable risk factors, a history of trauma and certain comorbid conditions increase the risk for developing SSTIs.6 Patients hospitalized with SSTI often have comorbid conditions, especially diabetes, have failed outpatient antibiotics, and have signs of systemic infection.2,7 Patients with SSTIs caused by community-associated MRSA (CA-MRSA) have unique risk factors including injection drug use, which is associated with 16-fold increased risk of invasive MRSA infections.8,9
Patients with SSTI rarely suffer from serious complications or death,10,11 and the mortality rate has been estimated to be approximately 0.5% for patients hospitalized with SSTI.11 Approximately 10% of patients hospitalized with SSTI have an SSTI-related readmission within 30 days of discharge.10 Patients with an SSTI caused by CA-MRSA are at a high risk for recurrent infections.12
Patients with SSTI frequently seek medical care at a hospital ED.13 Of these patients, 15% are admitted to the hospital for treatment.2 The most common reason for hospital admission in a patient with an SSTI is for administration of intravenous antibiotics.2 Large lesion size (≥10 cm), patient age ≥65 years, comorbidity, systemic signs of infection and failure of outpatient antibiotic treatment are also associated with the decision to admit to the hospital for intravenous antibiotics.2
MRSA accounts for almost half of all SSTI involving S. aureus,14,15 and increases the risk of morbidity and mortality,14 as well as higher healthcare costs than infections of the skin caused by methicillin-sensitive S. aureus.16
Hospital admissions for SSTI impose a substantial burden in the US, with SSTIs accounting for roughly 10% of all infection-related hospitalizations.3 SSTIs are estimated to cause up to 870,000 hospital admissions, 6.3 million office visits, and approximately 3.4 million ED visits annually in the US, with higher rates of hospitalizations observed in older populations.17-19
Admissions for SSTI impose a substantial hospital cost in the US.20 An increase in S. aureus-associated SSTI has been a major contributor to the US burden of skin infections including hospitalizations,21 with methicillin-resistant isolates responsible for nearly half of S. aureus-associated SSTI.22
