Epidemiology of Methicillin-Resistant Staphylococcus aureus Diabetic Foot Infections in a Large Academic Hospital: Implications for Antimicrobial Stewardship

Abstract

IntroductionDiabetic 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.MethodsThis 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.ResultsOverall, 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.ConclusionsAlthough MRSA was the causative pathogen in a small number of DFI, antibiotic coverage targeted against MRSA was unnecessarily high.

Efficacy of Phage Cocktail AB-SA01 Therapy in Diabetic Mouse Wound Infections Caused by Multidrug-Resistant Staphylococcus aureus

“…Treatment of staphylococcal diabetic foot infections with antibiotics is becoming increasingly difficult because of the widespread presence of antibiotic-resistant S. aureus strains (10,11,28). Previous reports have shown the potential of phages as an alternative or adjunctive therapy to treating bacterial infections in an animal model (29,30), but information regarding the treatment of human DFUs caused by MDR S. aureus using a phage cocktail topically is limited.…”

“…S. aureus is a virulent pathogen frequently isolated from DFU (5,9,10). A study in Australia found that two-thirds of DFU patients were infected with S. aureus, and nearly half were methicillin-resistant (MRSA), for which there are limited antimicrobial treatment options (11).…”

A role of methicillinresistant Staphylococcus aureus strains and related molecular genetic features in developing purulent-necrotic forms of the diabetic foot syndrome

“…Доля S. aureus среди всех возбудителей гнойно-некротических осложнений синдрома диабетической стопы в первые сутки госпитализации составила 18,4%, на 5-50 сутки -23,7%. По результатам микробиологических исследований биоптатов пациентов с синдромом диабетической стопы за рубежом доля S. aureus составляет 15-50% [26], таким образом, наши результаты соответствуют общемировым. В плане распространенности полирезистентных микроогранизмов среди данной категории пациентов, в частности доли MRSA, БЛРС-продуцирующих энтеробактерий, МБЛположительных p. Pseudomonas, p. Acinetobacter, выделенных в первые сутки госпитализации и на 5-50 сутки, также существенных различий не выявлено (p > 0,05).…”

“…В США частота ампутаций, связанных с диабетом, составляет 66 тыс. случаев в год; в 50-70% случаев причиной ампутации стопы является гангрена [26]. Пребывание пациентов с сахарным диабетом и с гнойно-некротическими поражениями в стационаре на 50% дольше [8].…”

“…Предшествующая госпитализация, длительная антибиотикотерапия препаратами широкого спектра действия и хирургическое лечение являются предрасполагающими факторами к инфицированию язв полирезистентными микроорганизмами, например метициллинрезистентными S. aureus (MRSA) и полирезистентными энтерококками, что значительно ухудшает прогноз у пациентов с диабетической стопой [8,23]. Таким образом, одним из ведущих возбудителей гнойных осложнений у пациентов с синдромом диабетической стопы является MRSA, доля которых среди S. aureus у данных пациентов в США составляет 40-50% [26].…”