Fungal Osteomyelitis in Diabetic Foot Infections: A Case Series and Comparative Analysis

The Microbial Diversity and Antimicrobial Susceptibility Profile Underlying Diabetic Foot Osteomyelitis: A Retrospective Study Conducted in North Queensland, Australia

Background

Diabetic foot osteomyelitis (DFO) commonly occurs secondary to ulcerations of the skin. Empirical antibiotic agents are a key element of treatment and their use is dependent on local knowledge of the microbial spectrum of diabetic foot infections. This study aimed to retrospectively analyze the local microbiological profile, including bacterial culture/sensitivity results of DFO, and compare findings with literature. This study also aimed to review the concordance of microbiology results with national guidelines for the future treatment of DFO.

Methods

A retrospective review of clinical records was performed on patients who presented to the high-risk foot clinic, Townsville University Hospital, between 2018 and 2022. All patients older than 18 years and diagnosed with DFO were included. Our exclusion criteria included all other foot presentations, including trauma, vasculitis, and neoplasms.

Results

On the basis of the inclusion and exclusion criteria, 124 patients with DFO were selected. Most patients in the cohort were males (70.2%), non-Indigenous (68.5%), aged 50-69 years (55.6%), and with elevated HbA1c levels (>8.6). Chronic kidney disease (39.5%) and ischemic heart disease (41.9%) were common comorbidities. Of the pertinent microbial results, Staphylococcus aureus (~76%) was the most commonly isolated Gram-positive organism. Gram-positive bacteria were significantly increased in the elderly population with DFO (P < .05). All methicillin-resistant S aureus isolates were vancomycin- and cotrimoxazole-sensitive. Pseudomonas aeruginosa was the predominant Gram-negative organism isolated (39.3%). P aeruginosa exhibited low sensitivity to ciprofloxacin.

Conclusion

This study has enhanced our understanding of the various microbial species underlying DFO at our center and may be generalizable.

Level of Evidence

Level IV, retrospective case series.

Microbiology of diabetic foot osteomyelitis - Is it geographically variable?

INTRODUCTION

Diabetic foot osteomyelitis (DFO) is a dreaded complication as both diagnosis and treatment of the condition is laborious. However, for proper decision on antibiotics in medical management of DFO, accurate determination of microbes is necessary to narrow the spectrum of coverage and to reduce adverse effects of long-term administration of antibiotics. With differing pattern of use of antimicrobials and their resistance pattern in different countries, it is empirical to determine the microbiological characteristics of bone cultures in DFO from a referral institute in South India.

MATERIALS AND METHODS

This study was a retrospective chart review of all cases of proven DFO who had consented for debridement and bone culture or those who underwent amputation. Both deep soft tissue (DST) and bone cultures were obtained for aerobic bacteria. Clinical characteristics and site(s) of DFO were recorded. Investigations for peripheral artery disease were performed if clinically indicated.

RESULTS

In all, 105 patients with DFO were reviewed. Mean age was 62 years and 70% were men. Of those who were screened, 57% had evidence of peripheral arterial disease by arterial doppler. 46% of bone culture samples were sterile. Gram- negative organisms were more common (58%). Following staphylococcus, pseudomonas was the second common isolate. Of total staphylococcal isolates 37% were MRSA and 33% of klebsiella isolates were ESBL producing. Concordance rate between DST and bone cultures was 66%. 90% were mono-bacterial isolates. The commonest site of involvement of DFO was terminal phalanges of toes rather than base of 1st metatarsal.

CONCLUSION

Widespread use of antibiotics, tropical climate and route of entry of organisms causing DFO differed in our cohort of patients. Further studies from different regions of world would shed light onto different pattern of microbes causing DFO.

Maxillary Fungal Osteomyelitis Mimicking and Treated as Endodontic Pathosis

Fungal osteomyelitis is a lethal opportunistic infection that affects only a small percentage of patients present to endodontists. It is a highly contagious infection that requires urgent treatment. We discuss three cases in which endodontic pathology was initially recognized but subsequent follow-up revealed severe osteolytic fungal infection of the maxilla manifesting as acute apical abscesses in the maxillary canine region. CBCT demonstrated osteolytic abnormalities, and further histology confirmed the illness was caused by mucormycosis in patients with uncontrolled diabetes mellitus and exposure to COVID-19.

Isolation and characterization of bacteria from diabetic foot ulcer: amputation, antibiotic resistance and mortality rate

Background

Diabetic foot ulcer (DFU) is one of the most serious complications of diabetes mellitus with devastating outcomes. Poorly treated DFU leads to osteomyelitis, gangrene and limb amputation. There is an increased risk of mortality for the amputees and increased number of bacterial resistance in survived patients. Struggle on choice of the best antibiotic(s) for DFU is escalating.

Objectives

To determine risk factors associated with mortality in patients with DFU. To investigate bacterial drug resistance in survived or deceased patients around amputation.

Methodology

This is a retrospective cohort study that involved all diabetic patients who had DFU or minor or major amputation at Hebron Governmental Hospital from 2013 to 2020. Antibiotic use and bacterial isolates along with culture and sensitivity test results were retrieved from patients' profiles and laboratory records. Major outcome of study was survival rate around amputation. Patients who missed test results for FBS or HbAc1, or who had no wound culture were excluded. SPSS version 22 was used to analyze data.

Results

Eighty four subjects were included in this study, 64.8 ± 12.58 years old, 63.1% males who had diabetic foot ulcer, minor or major limb amputation between 2013 and 2020 at Hebron Governmental Hospital. Forty tow patients (50%) had diabetic foot ulcer, 28 patients (33.3%) had major limb amputation, and 14 patients (16.7%), succumbed to minor amputation. Average FBS was 292.8 ± 136.33 mg/dl and average HbA1C was 8.55 ± 1.89%. Mortality rate was 9.5%. Using the Chi square test, we found a significant relationship between mortality and type of isolated bacteria, p = 0.033 and between diabetic complications (nephropathy) and mortality, p = 0.033. There was a significant relationship between antibiotic use and mortality, p = 0.04, especially with metronidazole and colistin, if they were used around limb amputation.

Conclusions

Mortality of diabetic patients with DFU was associated with nephropathy and Acinetobacter or E. coli infections.

Emerging Diabetic Foot Ulcer Microbiome Analysis Using Cutting Edge Technologies

One of the most prevalent complications of diabetes mellitus are diabetic foot ulcers (DFU). Diabetic foot ulcers represent a complex condition placing individuals at-risk for major lower extremity amputations and are an independent predictor of patient mortality. DFU heal poorly when standard of care therapy is applied. In fact, wound healing occurs only approximately 30% within 12 weeks and only 45% regardless of time when standard of care is utilized. Similarly, diabetic foot infections occur in half of all DFU and conventional microbiologic cultures can take several days to process before a result is known. DFU represent a significant challenge in this regard because DFU often demonstrate polymicrobial growth, become resistant to preferred antibiotic therapy, and do not inform providers about long-term prognosis. In addition, conventional culture yields may be affected by the timing of antibiotic administration and collection of tissue for analysis. This may lead to suboptimal antibiotic administration or debilitating amputations. The microbiome of DFU is a new frontier to better understand the interactions between host organisms and pathogenic ones. Newer molecular techniques are readily available to assist in analyzing the constituency of the microbiome of DFU. These emerging techniques have already been used to study the microbiome of DFU and have clinical implications that may alter standard of care practice in the near future. Here emerging molecular techniques that can provide clinicians with rapid DFU-related-information and help prognosticate outcomes in this vulnerable patient population are presented.

Candida parapsilosis osteomyelitis following dog bite: a case report and review of the literature

Candida osteomyelitis is uncommon, especially after dog bites. We describe a case of a 63-year-old man without significant comorbidities presenting progressing swelling of the distal interphalangeal joint (DIJ) of right index finger following a dog bite. Despite empiric antibiotic therapy and local medications, there were no clinical signs of improvement. Clinical examination revealed fistula with purulent drainage on the volar region. Even though laboratory data showed inflammatory markers on range, magnetic resonance imaging (MRI) demonstrated signs of osteomyelitis. The patient was taken to exploration and debridement of the bite wound. Culture of the bone biopsy showed growth of Candida parapsilosis. Therefore, the patient was diagnosed with isolated fungal osteomyelitis and was initiated on fluconazole therapy. The treatment was effective and all symptoms were resolved in 8 weeks after the surgery. There were no signs of recurrence after 20 months of follow-up. The patient had no cosmetic abnormalities or sequelae. Concurrently with the description of the case report a review of the literature was provided. According to the authors, there are three main etiopathogenesis for this infection. The first pathogenic mechanism is direct inoculation into the deep tissues through the dog bite. The second hypothesis is direct translocation of the pathogen from the skin to the deep tissue and to the bone. The last mode of transmission is hematogenous dissemination. Fungal osteomyelitis are really rare conditions, especially after dog bites, but nevertheless it should be considered as a possible diagnosis when there is no response to antibiotics.

Efficacy of Topical Vancomycin- and Gentamicin-Loaded Calcium Sulfate Beads or Systemic Antibiotics in Eradicating Polymicrobial Biofilms Isolated from Diabetic Foot Infections within an In Vitro Wound Model

Diabetic foot ulcers are notoriously difficult to heal, with ulcers often becoming chronic, in many cases leading to amputation despite weeks or months of antibiotic therapy in addition to debridement and offloading. Alternative wound biofilm management options, such as topical rather than systemic delivery of antimicrobials, have been investigated by clinicians in order to improve treatment outcomes. Here, we collected blood and tissue from six subjects with diabetic foot infections, measured the concentrations of antibiotics in the samples after treatment, and compared the microbiota within the tissue before treatment and after 7 days of antibiotic therapy. We used an in vitro model of polymicrobial biofilm infection inoculated with isolates from the tissue we collected to simulate different methods of antibiotic administration by simulated systemic therapy or topical release from calcium sulfate beads. We saw no difference in biofilm bioburden in the models after simulated systemic therapy (representative of antibiotics used in the clinic), but we did see reductions in bioburden of between 5 and 8 logs in five of the six biofilms that we tested with topical release of antibiotics via calcium sulfate beads. Yeast is insensitive to antibiotics and was a component of the sixth biofilm. These data support further studies of the topical release of antibiotics from calcium sulfate beads in diabetic foot infections to combat the aggregate issues of infectious organisms taking the biofilm mode of growth, compromised immune involvement, and poor systemic delivery of antibiotics via the bloodstream to the site of infection in patients with diabetes.

Management of bacterial skin and skin structure infections with polymicrobial etiology

INTRODUCTION

Skin and Soft Tissue Infections (SSTIs) are some of the most commonly occurring bacterial infections, with a wide range of possible etiological pathogens and a considerable variety of clinical presentations and severity; from mild to severe life-threatening infections. Several classifications have been proposed based on a specific variable, such as anatomical localization, skin extension, progression rate, clinical presentation, severity, and etiological agent. Areas covered: The last criteria allows the differentiation of SSTIs as monomicrobial and polymicrobial. Among them, especially those infections with a long lasting or chronic course can be sustained by multiple microbial etiology. Most polymicrobial SSTIs can be included in the following: diabetes foot infections (DFIs), pressure ulcers infection, burn infection, and infected chronic ulcers. Expert commentary: The medical management of these infections comprises the administration of wide a spectrum antibiotic, taking into consideration the frequent occurrence of multidrug resistant microorganisms as responsible agents. An appropriate deep tissue specimen for microbiological examination is a very important issue, especially for polymicrobial infections, sometimes permitting the distinction between real pathogens and contaminants avoiding more complex antibiotic treatments. This aspect must be strongly emphasized, as frequently superficial swabs remain the specimen of choice because they are easy to obtain.