The use of antibiotics is the single most important driver in antibiotic resistance. Nevertheless, antibiotic overuse remains common. Decline in antibiotic prescribing in the United States coincided with the launch of national educational campaigns in the 1990s and other interventions, including the introduction of routine infant immunizations with the pneumococcal conjugate vaccine (PCV-7); however, it is unknown if these trends have been sustained through recent measurements.

Diabetic foot infections (DFIs) are the leading cause of non-traumatic lower extremity amputations in the United States. Antimicrobials active against methicillin-resistant Staphylococcus aureus (MRSA) are recommended in patients with associated risk factors; however, limited data exist to support these recommendations. Due to the changing epidemiology of MRSA, and the consequences of unnecessary antibiotic therapy, guidance regarding the necessity of empirical MRSA coverage in DFIs is needed. We sought to 1) describe the prevalence of MRSA DFIs at our institution and compare to the proportion of patients who receive MRSA antibiotic coverage and 2) identify risk factors for MRSA DFI. This was a retrospective cohort study of all adult, culture-positive DFI patients managed at University Hospital, San Antonio, TX between January 1, 2010 and September 1, 2014. Patient eligibility included a principal ICD-9-CM discharge diagnosis code for foot infection and a secondary diagnosis of diabetes. The primary outcome was MRSA identified in the wound culture. Independent variables assessed included patient demographics, comorbidities, prior hospitalization, DFI therapies, prior antibiotics, prior MRSA infection, and laboratory values. Multivariable logistic regression was used to identify risk factors for MRSA DFI. Overall, 318 patients met inclusion criteria. Patients were predominantly Hispanic (79%) and male (69%). Common comorbidities included hypertension (76%), dyslipidemia (52%), and obesity (49%). S. aureus was present in 46% of culture-positive DFIs (MRSA, 15%). A total of 273 patients (86%) received MRSA antibiotic coverage, resulting in 71% unnecessary use. Male gender (OR 3.09, 95% CI 1.37–7.99) and bone involvement (OR 1.93, 1.00–3.78) were found to be independent risk factors for MRSA DFI. Although MRSA was the causative pathogen in a small number of DFI, antibiotic coverage targeted against MRSA was unnecessarily high.

Prior studies have demonstrated an increase in Clostridium difficile infection (CDI) incidence in the United States (U.S.) in recent years, but trends among different age groups have not been evaluated. This study describes national CDI incidence by age group over a 10-year period and mortality and hospital length of stay (LOS) among patients with CDI. This was a retrospective analysis of the U.S. National Hospital Discharge Surveys from 2001 to 2010. Eligible patients with an ICD-9-CM discharge diagnosis code for CDI (008.45) were stratified by age: <18 years (pediatrics), 18–64 years (adults), and ≥65 years (elderly adults). Data weights were used to derive national estimates. CDI incidence was calculated as CDI discharges/1000 total discharges. Mortality and LOS were compared between age groups using chi-square or Wilcoxon rank sum tests. These data represent 2.3 million hospital discharges for CDI over the study period. CDI incidence was highest among elderly adults (11.6 CDI discharges/1000 total discharges), followed by adults (3.5 CDI discharges/1000 total discharges) and pediatrics (1.2 CDI discharges/1000 total discharges). The elderly also had higher rates of mortality (8.8%) compared to adults (3.1%) and pediatrics (1.4%) (p < 0.0001). In addition, median hospital LOS was highest in the elderly (8 days) compared to adults (7 days) and pediatrics (6 days) (p < 0.0001). CDI incidence among patients hospitalized in U.S. hospitals differed based on age group between 2001 and 2010. CDI incidence, mortality, and hospital LOS were highest in the elderly adult population.