Comparative Clinical Outcomes of Patients with Diabetic Foot Infection Caused by Methicillin-Resistant Staphylococcus Aureus (MRSA) or Methicillin-Sensitive Staphylococcus Aureus (MSSA)

Methicillin-resistant Staphylococcus aureus in diabetic and non-diabetic foot infections

To identify the incidence of methicillin-resistant Staphylococcus aureus (MRSA) infection, reinfection and clinical outcomes. Four hundred forty-six patients that were admitted to the hospital with moderate or severe foot infections were retrospectively reviewed. Tissue and bone cultures were obtained from the index hospital admission. Conversion was defined as methicillin susceptible Staphylococcus aureus in the first culture and subsequently MRSA when there was a reinfection. The incidence of MRSA was 7.8% (n = 35), with no significant difference between soft tissue infections (7.7%) and osteomyelitis (8.0%). MRSA incidence was 9.4 times higher in non-diabetics (23.8% vs. 3.2%, p = <0.01). The incidence of reinfection was 40.8% (n = 182). Conversion to MRSA was seen in 2.2% (n = 4) total, occurring in 5.4%. Non-diabetics were 20.1 times more likely to have MRSA reinfection than people with diabetes (28.6% vs. 1.9%, p < 0.001). MRSA patients had a higher proportion of healed wounds (82.4% vs. 69.3%, p = 0.02). There were no differences in other clinical outcomes in MRSA vs. other infections in reinfection (28.6% vs. 24.3%, p = 0.11), amputation (48.6% vs. 52.0%, p = 0.69) or hospitalization (28.6% vs. 42.6, p = 0.11). The incidence of MRSA for the first infection (7.8%), reinfection (6.0%) and conversion to MRSA (2.2%) was low. MRSA was 9.4 times more common in people without diabetes.

Determining the Best Noninvasive Test for Peripheral Arterial Disease Diagnosis to Predict Diabetic Foot Ulcer Healing in Patients Following Endovascular Revascularization

BACKGROUND/OBJECTIVES

To analyze the best noninvasive tests prognosis marker in patients with diabetic foot ulcer (DFU) who underwent endovascular revascularization based on clinical outcomes, such as healing rate, time to heal, and free amputation survival after at least a six-month follow-up.

METHODS

A multicentric prospective observational study was performed with 28 participants with ischemic or neuroischemic DFU who came to the participant centers and underwent endovascular revascularization between January 2022 and March 2023. Toe systolic pressure (TP), ankle systolic pressure (AP), the ankle brachial pressure index (ABPI), the toe brachial pressure index (TBPI), transcutaneous pressure of oxygen (TcPO2), and skin perfusion pressure (SPP) were evaluated using PeriFlux 6000 System, Perimed, Sweden, before (Visit 0) and four weeks after revascularization (Visit 1). The primary clinical outcome was an evaluation of the clinical evolution of noninvasive tests comparing Visit 0 and Visit 1, estimating the sensitivity for predicting wound healing of noninvasive tests at six months following initial recruitment.

RESULTS

After six months, 71.43% (n = 20) of DFU healed, four patients (14.3%) received major amputations, and one (3.5%) died. The two tests that best predicted wound healing after revascularization according to the ROC curve were TcPO2 and TP with sensitivities of 0.89 and 0.70 for the cut-off points of 24 mmHg and 46 mmHg, respectively.

CONCLUSIONS

TcPO2 and TP were the two tests that best predicted wound healing in patients who underwent endovascular revascularization. Clinicians should consider the importance of the evaluation of microcirculation in the healing prognosis of patients with diabetic foot ulcers.

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.

MRSA infection, re-infection and clinical outcomes in diabetic foot infections

The aim was to investigate methicillin-resistant Staphylococcus aureus (MRSA) incidence, conversion and outcomes in diabetic foot infections (DFIs). This is a pooled patient-level analysis of combined data sets from two randomised clinical trials including 219 patients admitted to the hospital with moderate or severe DFIs. Intraoperative bone and tissue cultures identified bacterial pathogens. We identified pathogens at index infections and subsequent re-infections. We identified MRSA conversion (MSSA to MRSA) in re-infections. MRSA incidence in index infections was 10.5%, with no difference between soft tissue infections (STIs) and osteomyelitis (OM). MRSA conversion occurred in 7.7% of the re-infections in patients who initially had MSSA in their cultures. Patients with re-infection were 2.2 times more likely to have MRSA compared to the first infection (10.5% vs. 25.8%, relative risk [RR] = 2.2, p = 0.001). Patients with MRSA had longer antibiotic treatment during the 1-year follow-up, compared to other pathogens (other 49.8 ± 34.7 days, MRSA 65.3 ± 41.5 days, p = 0.04). Furthermore, there were no differences in healing, time to heal, length of stay, re-infection, amputation, re-ulceration, re-admission, surgery after discharge and amputation after discharge compared to other pathogens. The incidence of MRSA at the index was 10.5% with no difference in STI and OM. MRSA incidence was 25.8% in re-infections. The RR of having MRSA was 2.2 times higher in re-infections. Patients with MRSA used more antibiotics during the 1-year follow-up. Furthermore, there were no differences in clinical outcomes compared to other bacterial pathogens.

Analysis of the Influence of Diabetic Nephropathy in Patients with Diabetic Foot Osteomyelitis

This study analyzed the influence of diabetic nephropathy on the healing prognosis after conservative surgery in diabetic foot osteomyelitis (DFO). A retrospective observational study was carried out between January 2021 and December 2022 and involved 278 outpatients with a diagnosis of DFO at a specialized diabetic foot unit, including 74 (26.62%) patients with DN (group 2) and 204 (73.38%) patients without DN (group 1). There were 266 (95.70%) ulcers on the forefoot, 8 (2.90%) on the midfoot, and 4 (1.45%) on the hindfoot (p = 0.992). The healing rates were 85.1% (n = 63) for group 2 and 81.3% (n = 165) for group 1 (p = 0.457). When exploring the influence of DN on the risk of delayed ulcer healing, the results did not show a significant effect [12 (6; 28) weeks among patients with DN vs. 12 (6; 21) weeks among patients without DN; p = 0.576]. No significant differences were observed in complications, with one (2.59%) death occurring in group 1 (p = 0.296) and three minor amputations being performed in both groups [two (5.13%) amputations in group 1 vs. one amputation (9.09%) in group 2; p = 0.217]. Bone cultures were performed for a total of 190 patients (133 in group 1 and 57 in group 2). Of these, 176 positive bone cultures were isolated: 71 positive bone cultures (57.7%) were monomicrobial cultures in group 1, with 30 (56.6%) in group 2. There were 52 (42.3%) that had at least two microorganisms in group 1, and 23 (43.4%) in group 2 (p = 0.890). The most frequently prescribed oral antibiotic was amoxicillin/clavulanate (43.89%), followed by levofloxacin (28.4%), and trimethoprim/sulfamethoxazole (14.7%). This study shows that DN does not have a significant influence on the healing prognosis of patients with DFO after conservative surgery.