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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.
Background
We aimed to evaluate surrogate markers commonly used in the literature for diabetic foot osteomyelitis remission after initial treatment for diabetic foot infections (DFIs).
Methods
Thirty-five patients with DFIs were prospectively enrolled and followed for 12 months. Osteomyelitis was determined from bone culture and histologic analysis initially and for recurrence. Fisher exact and χ2 tests were used for dichotomous variables and Student t and Mann-Whitney U tests for continuous variables (α = .05).
Results
Twenty-four patients were diagnosed as having osteomyelitis and 11 as having soft-tissue infections. Four patients (16.7%) with osteomyelitis had reinfection based on bone biopsy. The success of osteomyelitis treatment varied based on the surrogate marker used to define remission: osteomyelitis infection (16.7%), failed wound healing (8.3%), reulceration (20.8%), readmission (16.7%), amputation (12.5%). There was no difference in outcomes among patients who were initially diagnosed as having osteomyelitis versus soft-tissue infections. There were no differences in osteomyelitis reinfection (16.7% versus 45.5%; P = .07), wounds that failed to heal (8.3% versus 9.1%; P = .94), reulceration (20.8% versus 27.3%; P = .67), readmission for DFIs at the same site (16.7% versus 36.4%; P = .20), amputation at the same site after discharge (12.5% versus 36.4%; P = .10). Osteomyelitis at the index site based on bone biopsy indicated that failed therapy was 16.7%. Indirect markers demonstrated a failure rate of 8.3% to 20.8%.
Conclusions
Most osteomyelitis markers were similar to markers in soft-tissue infection. Commonly reported surrogate markers were not shown to be specific to identify patients who failed osteomyelitis treatment compared with patients with soft-tissue infections. Given this, these surrogate markers are not reliable for use in practice to identify osteomyelitis treatment failure.
Herpetic whitlow is a viral infection of the fingers or toes caused by the herpes simplex virus. Herpes simplex virus is a common pathogen that causes infections in any cutaneous or mucocutaneous surface, most commonly gingivostomatitis or genital herpes. However, infection of the digits is also infrequently reported. Herpetic whitlow occurs when the virus infects the distal phalanx of the fingers or toes by means of direct inoculation, causing pain, swelling, erythema, and vesicle formation. The proper diagnosis is important because the condition can mimic various other podiatric abnormalities such as paronychia, bacterial cellulitis, or even embolic disease. Improper diagnosis often leads to unnecessary work-up, antibiotic therapy, or even surgical intervention. This case will help illuminate the clinical presentation of herpetic whitlow in an atypical location, and the patient’s subsequent treatment. We present an atypical case of right hallux herpetic whitlow with delayed diagnosis and associated cellulitis. The patient was admitted after seeing multiple providers for a progressive right hallux infection that presented as a mixture of vesicular lesions and apparent cellulitis. His history was positive for biting his fingernails and toenails, and the lesions were noted to be honeycomb-like, with minimal drainage. The lesions were then deroofed and viral cultures were obtained, which were positive for herpes simplex virus type 1, thus confirming a diagnosis of herpetic whitlow. Although he remained afebrile with negative wound cultures during admission, a secondary bacterial infection could not be excluded because of his nail avulsion and surrounding cellulitis. He was discharged on oral antibiotics, antivirals, and wound care recommendations. Herpetic whitlow should be included in the differential diagnosis of pedal digital lesions that appear as vesicular or cellulitic in the pediatric population.
Antibiotic Stewardship
The Lower-Extremity Physician's Prescription for Effectively Treating Infection
The discovery of antibiotic drugs was one of the most significant medical achievements of the 20th century. The improper use of antibiotic drugs to prevent and treat infections has resulted in the emergence of resistance. Antimicrobic stewardship programs are becoming a mainstay in the fight against multidrug-resistant organisms. Individual clinicians should be encouraged to adopt the principles of antibiotic stewardship when treating lower-extremity infections in their scope of practice. First, a review of the available literature outlining the concept and practice of antibiotic stewardship is offered. Second, a discussion describing how to adopt and apply these principles to the individual clinician's practice as it applies to lower-extremity infections is offered. Finally, specific antimicrobial pharmacologic spectra and antibiogram information are offered.
Background: Fungal foot infection is a common superficial fungal infection and is recognized as an important public health problem. Related to the wearing of occlusive footwear, foot infection is usually caused by dermatophytes and nondermatophyte molds. Previous in vitro studies have demonstrated that zinc oxide nanoparticles (ZnO-NPs) have antimicrobial activity against fungi. This study, therefore, evaluated the ability of socks coated with ZnO-NPs to inhibit fungal growth in an in vitro model mimicking real-life situations.
Methods: Scale from patients with fungal foot infections was equally divided into three groups: control, plain socks, and ZnO-NP socks. The specimens in the control group were routinely fungal cultured, whereas in the plain sock and ZnO-NP sock groups, scale was incubated with plain socks and ZnO-NP socks, respectively, for 24 hours. After incubation, each piece of sock was cultured. The fungal culture results of the three groups were progressively evaluated for 4 weeks.
Results: From 31 specimens, the positive fungal culture results of the control, plain sock, and ZnO-NP sock groups were 100%, 64.5%, and 54.8%, respectively. Specimens incubated with plain socks (P = .001) or with ZnO-NP socks (P < .001) had a significant reduction in the number of positive fungal cultures compared with the control.
Conclusions: Plain socks and ZnO-NP socks significantly inhibited fungal growth relative to the control. The wearing of either plain socks or ZnO-NP socks can prevent fungal foot infection because these socks act as a barrier to the insoles of shoes.
The Diagnosis of Onychomycosis in a Geriatric Population
A Study of 450 Cases in South Florida
An investigative study was performed to determine the diagnosis of onychomycosis in a South Florida geriatric population. In this study, 450 cases of suspected onychomycosis involving men and women 65 years of age and older from a private practice office and two nursing home settings were used. Samples were taken from the hallux toenail and sent to a mycology laboratory for fluorescent potassium hydroxide (KOH) preparation and microscopic examination of a fungal culture. Of the 450 cases studied, 46.4% of the patients had a single fungal organism cultured, 30.4% had a mixed fungal infection cultured, and 23.1% had no fungal growth. Saprophytes were found in 59.9% of the 526 total fungal organisms cultured while dermatophytes were found in only 23.8%. The results of this investigation demonstrate that there may be a shift from isolated dermatophyte infection to mixed saprophyte infections in a geriatric population with onychomycosis. (J Am Podiatr Med Assoc 91(9): 456-464, 2001)
Streptococcus anginosus (SAG) is a known human pathogen and member of the Streptococcus milleri group. SAG is a known bacterial cause of soft-tissue abscesses and bacteremia and is an increasingly prevalent pathogen in infections in patients with cystic fibrosis. We describe a rare case of SAG as an infectious agent in a case of nonclostridial myonecrosis with soft-tissue emphysema. This is the only case found in the literature of SAG cultured as a pure isolate in this type of infection and was associated with a prolonged course of treatment in an otherwise healthy patient.
Stevens-Johnson syndrome and toxic epidermal necrolysis are rare; however, when they occur, they usually present with severe reactions in response to medications and other stimuli. These reactions are characterized by mucocutaneous lesions, which ultimately lead to epidermal death and sloughing. We present a unique case report of Stevens-Johnson syndrome and associated toxic epidermal necrolysis in a 61-year-old man after treatment for a peripherally inserted central catheter infection with trimethoprim-sulfamethoxazole. This case report reviews a rare adverse reaction to a commonly prescribed antibiotic drug used in podiatric medical practice for the management of diabetic foot infections. (J Am Podiatr Med Assoc 100(4): 299–303, 2010)
Most fungal infections primarily occur in immunocompromised patients. We describe a case of osteomyelitis involving the first metatarsal head due to Cryptococcus neoformans in a previously healthy immunocompetent patient. She was treated with surgical debridement combined with antifungal drug therapy for 6 months. At 5-year follow-up, she remained symptom free with full range of motion of the first metatarsophalangeal joint. Fungal osteomyelitis should be considered as a possible cause in osteolytic lesions in the metatarsal bone.
