Onychomycosis is estimated to occur in approximately 10% of the global population, with most cases caused by Trichophyton rubrum. Some persistent onychomycosis is caused by mixed infections of T rubrum and one or more co-infecting nondermatophyte molds (NDMs). In onychomycosis, T rubrum strain types may naturally switch and may also be triggered to switch in response to antifungal therapy. T rubrum strain types in mixed infections of onychomycosis have not been characterized.
T rubrum DNA strains in mixed infections of onychomycosis containing co-infecting NDMs were compared with a baseline North American population through polymerase chain reaction amplification of ribosomal DNA tandemly repetitive subelements (TRSs) 1 and 2. The baseline DNA strain types were determined from 102 clinical isolates of T rubrum. The T rubrum DNA strain types from mixed infections were determined from 63 repeated toenail samples from 15 patients.
Two unique TRS-2 types among the clinical isolates contributed to four unique TRS-1 and TRS-2 strain types. Six TRS-1 and TRS-2 strain types represented 92% of the clinical isolates of T rubrum. Four TRS-1 and TRS-2 strain types accounted for 100% of the T rubrum within mixed infections.
Four unique North American T rubrum strains were identified. In support of a shared ancestry, the T rubrum DNA strain types found in mixed infections with NDMs were among the most abundant types. A population of T rubrum strains in mixed infections of onychomycosis has been characterized, with more than one strain detected in some nails. The presence of a co-infecting NDM in mixed infections may contribute to failed therapy by stabilizing the T rubrum strain type, possibly preventing the antifungal therapy–induced strain type switching observed with infections caused by T rubrum alone.
Reports of mixed infections with nondermatophyte molds (NDMs) and dermatophytes in onychomycosis are rare, possibly owing to the inhibition of NDM growth during traditional culture. We sought to determine the prevalence of mixed infections in onychomycosis using molecular identification.
Molecular analyses were used to identify infecting organisms directly from at least two serial great toenail samples from each of the 44 patients.
Mixed infections were present in 41% of the patients (18 of 44). A single coinfecting NDM was the most common mixed infection and was detected in 34% of patients with onychomycosis (15 of 44), with Fusarium oxysporum present in 14% (6 of 44), Scopulariopsis brevicaulis in 9% (4 of 44), Acremonium spp in 2% (1 of 44), Aspergillus spp in 4.5% (2 of 44), and Scytalidium spp in 4.5% (2 of 44). Mixed infections with two NDMs were found in 7% of patients (3 of 44).
Mixed onychomycosis infections may be more prevalent than previously reported.
Hematoma refers to the collection or extravasation of blood, usually clotted, in a closed tissue space. It is caused by leakage from local vessels damaged by blunt trauma, local injury, or surgical dissection. In the postoperative phase, a hematoma often results in edema, pain, wound dehiscence, infection, and scarring of the surgical wound. We describe a 44-year-old woman who developed severe complications, including hematoma, abscess, failure of internal fixation, and loss of soft-tissue structures, after hallux abducto valgus surgery. Hospitalization was required for infection control, soft-tissue coverage through negative-pressure wound therapy, and first metatarsophalangeal joint stabilization through external fixation. Early recognition of the signs of infection and hematoma can help decrease the incidence of postoperative complications. (J Am Podiatr Med Assoc 97(5): 410–414, 2007)
A universally accepted histopathologic classification of diabetic foot osteomyelitis does not currently exist. We sought to evaluate the histopathologic characteristics of bone infection found in the feet of diabetic patients and to analyze the clinical variables related to each type of bone infection.
We conducted an observational prospective study of 165 diabetic patients with foot ulcers who underwent surgery for bone infection. Samples for microbiological and histopathologic analyses were collected in the operating room under sterile conditions.
We found four histopathologic types of osteomyelitis: acute osteomyelitis (n = 46; 27.9%), chronic osteomyelitis (n = 73; 44.2%), chronic acute osteomyelitis (n = 14; 8.5%), and fibrosis (n =32; 19.4%). The mean ± SD time between the initial detection of ulcer and surgery was 15.4 ± 23 weeks for acute osteomyelitis, 28.6 ± 22.4 weeks for chronic osteomyelitis, 35 ± 31.3 weeks for chronic acute osteomyelitis, and 27.5 ± 27.3 weeks for the fibrosis stage (analysis of variance: P = .03). Bacteria were isolated and identified in 40 of 46 patients (87.0%) with acute osteomyelitis, 61 of 73 (83.5%) with chronic osteomyelitis, 11 of 14 (78.6%) with chronic acute osteomyelitis, and 25 of 32 (78.1%) with fibrosis.
Histopathologic categorization of bone infections in the feet of diabetic patients should include four groups: acute, chronic, chronic acute, and fibrosis. We suggest that new studies should identify cases of fibrosis to allow comparison with the present results. (J Am Podiatr Med Assoc 103(1): 24–31, 2013)
Background: We sought to determine the similarity of pathogens isolated from soft tissue and bone in patients with diabetic foot infections. It is widely believed that soft-tissue cultures are adequate in the determination of causative bacteria in patients with diabetic foot osteomyelitis. The culture results of specimens taken concurrently from soft-tissue and bone infections show that the former does not predict the latter with sufficient reliability. We sought to determine the similarity of pathogens isolated from soft tissue and bone in patients with diabetic foot infections.
Methods: Forty-five patients with diabetic foot infections were enrolled in the study. Patients had to have clinically suspected foot lesions of grade 3 or higher on the Wagner classification system. In patients with clinically suspected osteomyelitis, magnetic resonance imaging, scintigraphy, or histopathologic examination were performed. Bone and deep soft tissue specimens were obtained from all patients by open surgical procedures under aseptic conditions during debridement or amputation. The specimens were compared only with the other specimens taken from the same patients.
Results: The results of bone and soft-tissue cultures were identical in 49% (n = 22) of cases. In 11% (n = 5) of cases there were no common pathogens. In 29% (n = 13) of cases there were more pathogens in the soft-tissue specimens; these microorganisms included microbes isolated from bone cultures. In four patients (9%) with culture-positive soft-tissue specimens, bone culture specimens remained sterile. In one patient (2%) with culture-positive bone specimen, soft-tissue specimen remained sterile.
Conclusion: Culture specimens should be obtained from both the bone and the overlying deep soft tissue in patients with suspected osteomyelitis whose clinical conditions are suitable. The decision to administer antibiotic therapy should depend on these results. (J Am Podiatr Med Assoc 98(4): 290–295, 2008)
Background: Prediction of amputation would aid clinicians in the management of diabetic foot infections. We aimed to assess the predictive value of baseline and post-treatment levels of acute phase reactants in the outcome of patients with diabetic foot infections.
Methods: We collected data prospectively during minimum follow-up of 6 months in patients with infected diabetic foot ulcers hospitalized in Dokuz Eylul University Hospital between January 1, 2003, and January 1, 2008. After excluding patients who did not attend the hospital for follow-up visits regularly (n = 36), we analyzed data from 165 foot ulcer episodes.
Results: Limb ischemia and osteomyelitis were much more frequent in patients who underwent amputation. Wagner grade, which assesses ulcer depth and the presence of osteomyelitis or gangrene, was higher in patients who needed amputation. Ulcer size was slightly larger in the amputation group. Baseline and post-treatment C-reactive protein levels, erythrocyte sedimentation rates, white blood cell counts, and platelet counts were significantly elevated in patients who underwent amputation. Albumin levels were significantly suppressed in the amputation group. Univariate analysis showed that a 1-SD increase in baseline and post-treatment C-reactive protein levels, erythrocyte sedimentation rates, and white blood cell counts and a 1-SD decrease in post-treatment albumin levels were significantly associated with increased risk of amputation. Post-treatment C-reactive protein level was strongly associated with amputation risk.
Conclusions: Circulating levels of acute phase reactants were associated with amputation risk in diabetic foot infections. (J Am Podiatr Med Assoc 101(1): 1–6, 2011)
Vancomycin is a common treatment option for skin and skin structure infections caused by methicillin-resistant Staphylococcus aureus (MRSA). Given the increasing prevalence of MRSA, vancomycin is widely used as empirical therapy. In patients with lower-limb infections, antimicrobial penetration is often reduced because of decreased vascular perfusion. In this study, we evaluated the tissue concentrations of vancomycin in hospitalized patients with lower-limb infections.
An in vivo microdialysis catheter was inserted near the margin of the wound and was perfused with lactated Ringer's solution. Tissue and serum samples were obtained after steady state for one dosing interval. Tissue concentrations were corrected for percentage of in vivo recovery using the retrodialysis technique.
Nine patients were enrolled (mean ± SD: age, 54 ± 19 years; weight, 105.6 ± 31.5 kg). Patients received a mean of 12.8 mg/kg of vancomycin every 12 hours (n = 7), every 8 hours (n = 1), or every 24 hours (n = 1). Mean ± SD steady-state trough vancomycin concentrations in serum and tissue were 11.1 ± 3.3 and 6.0 ± 2.6 μg/mL. The mean ± SD 24-hour free drug areas under the curve for serum and wound were 283.7 ± 89.4 and 232.8 ± 75.7 μg*h/mL, respectively. The mean ± SD tissue penetration ratio was 0.8 ± 0.2.
These data suggest that against MRSA with minimum inhibitory concentrations of 1 μg/mL or less, vancomycin achieved blood pharmacodynamic targets required for the likelihood of success. Reduced concentrations may contribute to poor outcomes and the development of resistance. As other literature suggests, alternative agents may be needed when the pathogen of interest has a minimum inhibitory concentration greater than 1 μg/mL.
The infected diabetic lower extremity has enjoyed a surge in popularity in the medical literature. There have been numerous papers outlining classification systems for ulcer depth, surgical approaches, and microbiology. Discussions on antibiotic use have usually been directed toward therapy of the "diabetic foot infections" as a group, without regard to differences in severity and location of these infections. These infections can vary from the most superficial of processes to a severe life- and limb-threatening sepsis. The author presents a review of the processes involved in the diabetic lower extremity infection and suggests a classification system for selection of empiric antibiotic therapy based on the severity of the infection.
The treating podiatric physician should consider underlying malignant disease when evaluating a child with any slowly healing or nonhealing infection involving the lower extremity. This article reports on an infant who was treated for suspected osteomyelitis involving his right fifth toe that did not improve with standard surgical, medical, and antibiotic treatments. He was later diagnosed as having acute myelogenous leukemia. (J Am Podiatr Med Assoc 97(2): 145–147, 2007)