Do Diabetic Foot Infections With Methicillin-ResistantStaphylococcus aureusDiffer From Those With Other Pathogens?

Abstract

There is controversy as to whether or not diabetic foot infections (DFIs) caused by methicillin-resistant Staphylococcus aureus (MRSA) are associated with worse outcomes than DFIs caused by other pathogens. To address this issue we performed a nonsystematic literature search of published articles in English language journals seeking studies reporting on the outcomes of DFIs related to their microbiology. We retrieved 48 articles published from 1999 to 2013 that described a total of 7771 cases of DFI. The overall proportion of DFIs with an isolate of S aureus was about 30%; just over one third of these (11% of all cases) were MRSA strains. Among the DFI cases caused by MRSA 1543 were episodes of soft tissue infections and 113 of osteomyelitis, while non-MRSA organisms caused 5761 soft tissue infections and 354 cases of osteomyelitis. Only 5 of the included articles attempted a comparison between DFI caused by MRSA and those caused by other pathogens, with no clear differences noted. The median total duration of antibiotic therapy for DFI caused by MRSA was 26 days, of which a median of 10 days was given intravenously. Only a few articles reported the proportion of patients with a recurrence, but they often did not differentiate between MRSA and non-MRSA cases. Four publications reported a worse functional or microbiological outcome in MRSA, compared to non-MRSA, cases, but the findings were variable and differences did not seem to be significant. Many trials failed to adjust for case-mix or to definitively demonstrate a relationship between microbiology and outcomes. Few of the articles specifically commented on whether the MRSA isolates were health care- or community-acquired strains. Notwithstanding the substantial limitations of the available literature, there does not appear to be a need for any special treatment for DFI caused by MRSA. The current guidelines for treating according to established international recommendations seem appropriate.

Stopping antibiotics after surgical amputation in diabetic foot and ankle infections—A daily practice cohort

“…Secondly, we did not analyse the antibiotic agents that were used, or the role of specific pathogens. This is based on the lack of evidence that any specific systemic antibiotic regimen is significantly superior for treatment of DFI, regardless of the involved pathogens . Our study population and pathogens recovered were consistent with those reported in the literature .…”

“…In total, 47 cases (10%) were complicated by bacteremia, 86 (18%) presented with soft tissue abscesses, and 139 (29%) with cellulitis. By notifying the three most prevalent microorganisms per DFI episode in our pathway, we detected 102 different microbiological combinations among the study population, with the four most frequently identified pathogens being Staphylococcus aureus (214 episodes, of which 53 were methicillin‐resistant), enterococci (n = 60), streptococci (n = 53) and Gram‐negative pathogens (n = 190, of which 35 Pseudomonas aeruginosa cases). Overall, 235 episodes (49%) were polymicrobial …”

Remission in diabetic foot infections: Duration of antibiotic therapy and other possible associated factors

“…Likewise, no study has linked any particular organism to treatment failure, which is not surprising given the polymicrobial nature of most DFIs. For example, we and others have shown that infection with methicillin‐resistant S. aureus or obligate anaerobes has not been shown to be more deleterious than other pathogens. Additionally, wound cultures from our patients demonstrated 112 different microbiological constellations, making adequate retrospective analyses difficult.…”

IWGDF guidance on the diagnosis and management of foot infections in persons with diabetes

“…Specifically, lower extremity amputation was performed during hospitalization in 35% and in another 19% of the 150 non‐amputated patients in the year after discharge; risk factors for amputation included severity of the infection and the presence of osteomyelitis. As in other studies , the presence of multidrug‐resistant pathogens [especially methicillin‐resistant S . aureus (MRSA)] was not associated with more severe infection or worse outcome.…”