SLR - December 2021 - Samuel R. Gorelik
Reference: Matheson EM, Bragg SQ, Blackweller RS. Diabetes-Related Foot Infections: Diagnosis and Treatment. American Family Physician. 104(4): Oct 2021. 386-394.Level of Evidence: Level VII
Scientific Literature Review
Reviewed By: Samuel R. Gorelik, DPM
Residency Program: Saint Vincent Hospital – Worcester, MA
Podiatric Relevance: This article presents a summary of treatments and recommendations for general physicians when evaluating a patient with a possible diabetic foot infection. It focuses on common mistakes that are done by physicians like taking superficial cultures, along with not realizing the multitude of diabetic foot infections are polymicrobial when prescribing antibiotics. Fifteen percent of infected wounds present as positive for MRSA. This greatly limits the kind of treatments a patient can get and may require IV antibiotics which can cause further damage to the body in patients who have other comorbidities to begin with. As a result of the infection and other comorbidities, a multimodal approach needs to be stimulated at the direction of the Podiatrist, including Infectious Disease, Vascular, Endocrine and others.
Methods: This article is a level VII study providing guidelines from a group of experts in the field using current literature.
Results: Diabetic foot infections occur in 40 percent of foot ulcers. Improper treatment or incorrect diagnoses can lead to serious morbidity and amputations in diabetic patients. There are certain risk factors that can increase the chances to develop foot infections. These factors include large foot ulcers greater than 2 centimeters, uncontrolled diabetes mellitus, and poor circulation. Clinical presentation of an infection typically includes erythema, induration, tenderness, warmth, and drainage. A probe-to-bone test is seen as a highly sensitive and specific test for osteomyelitis. Other important values include C-reactive protein and procalcitonin. Because diabetics may not exhibit a normal immune response, the WBC count may not always be accurate. The article also gives a detailed table on different antibiotics that should be used for mild, moderate and severe infections. The most common organisms isolated were Staphylococcus aureus, staphylococcus epidermidis, streptococcus agalactiae and Enterococcus. Gram negative bacteria is also commonly seen with Enterobacteriaceae and Pseudomonas aeruginosa being the most common. Anaerobes are also often seen with Bacteroides fragilis, Prevotella, Porphyromas, and Clostridium being most common.
Conclusions: It was emphasized that superficial wound cultures often contain contaminants thus making them not useful. Deep cultures are preferred. They also emphasized the benefits of performing an incision and drainage, debridement or a bone culture for source control and accurate cultures. Diabetic wounds should be treated with broad spectrum antibiotics until the bacteria is isolated and identified. Radiography can be used for initial imaging followed by MRI or CT based on the clinical picture. An ankle-brachial index is used to evaluate for blood flow to the extremities. The International Working Group on the diabetic foot made a new classification system ranging from one to four for the level of an infection given the clinical and laboratory findings of a patient. If someone presents with a more serious infection, then IV antibiotics are required. In regards to prevention, the Podiatrist needs to consider why it happened in the first place and if there are areas of concern for future skin breakdown. Bony prominences, the foot structure and biomechanics can give hints to areas at higher risk.