Foot infections are a common and serious problem in persons with diabetes. Diabetic
foot infections (DFIs) typically begin in a wound, most often a neuropathic ulceration.
While all wounds are colonized with microorganisms, the presence of infection is defined
by ≥2 classic findings of inflammation or purulence. Infections are then classified
into mild (superficial and limited in size and depth), moderate (deeper or more extensive),
or severe (accompanied by systemic signs or metabolic perturbations). This classification
system, along with a vascular assessment, helps determine which patients should be
hospitalized, which may require special imaging procedures or surgical interventions,
and which will require amputation. Most DFIs are polymicrobial, with aerobic gram-positive
cocci (GPC), and especially staphylococci, the most common causative organisms. Aerobic
gram-negative bacilli are frequently copathogens in infections that are chronic or
follow antibiotic treatment, and obligate anaerobes may be copathogens in ischemic
or necrotic wounds. Wounds without evidence of soft tissue or bone infection do not
require antibiotic therapy. For infected wounds, obtain a post-debridement specimen
(preferably of tissue) for aerobic and anaerobic culture. Empiric antibiotic therapy
can be narrowly targeted at GPC in many acutely infected patients, but those at risk
for infection with antibiotic-resistant organisms or with chronic, previously treated,
or severe infections usually require broader spectrum regimens. Imaging is helpful
in most DFIs; plain radiographs may be sufficient, but magnetic resonance imaging
is far more sensitive and specific. Osteomyelitis occurs in many diabetic patients
with a foot wound and can be difficult to diagnose (optimally defined by bone culture
and histology) and treat (often requiring surgical debridement or resection, and/or
prolonged antibiotic therapy). Most DFIs require some surgical intervention, ranging
from minor (debridement) to major (resection, amputation). Wounds must also be properly
dressed and off-loaded of pressure, and patients need regular follow-up. An ischemic
foot may require revascularization, and some nonresponding patients may benefit from
selected adjunctive measures. Employing multidisciplinary foot teams improves outcomes.
Clinicians and healthcare organizations should attempt to monitor, and thereby improve,
their outcomes and processes in caring for DFIs.