Microbial Community Distribution and Core Microbiome in Successive Wound Grades of Individuals with Diabetic Foot Ulcers

Abstract

Diabetic foot ulcer (DFU) is a major complication of diabetes with high morbidity and mortality rates. The pathogenesis of DFUs is governed by a complex milieu of environmental and host factors. The empirical treatment is initially based on wound severity since culturing and profiling the antibiotic sensitivity of wound-associated microbes is time-consuming. Hence, a thorough and rapid analysis of the microbial landscape is a major requirement toward devising evidence-based interventions. Toward this, 122 wound (100 diabetic and 22 nondiabetic) samples were sampled for their bacterial community structure using both culture-based and next-generation 16S rRNA-based metagenomics approach. Both the approaches showed that the Gram-negative microbes were more abundant in the wound microbiome. The core microbiome consisted of bacterial genera, including Alcaligenes, Pseudomonas, Burkholderia, and Corynebacterium in decreasing order of average relative abundance. Despite the heterogenous nature and extensive sharing of microbes, an inherent community structure was apparent, as revealed by a cluster analysis based on Euclidean distances. Facultative anaerobes (26.5%) were predominant in Wagner grade 5, while strict anaerobes were abundant in Wagner grade 1 (26%). A nonmetric dimensional scaling analysis could not clearly discriminate samples based on HbA1c levels. Sequencing approach revealed the presence of major culturable species even in samples with no bacterial growth in culture-based approach. Our study indicates that (i) the composition of core microbial community varies with wound severity, (ii) polymicrobial species distribution is individual specific, and (iii) antibiotic susceptibility varies with individuals. Our study suggests the need to evolve better-personalized care for better wound management therapies. IMPORTANCE Chronic nonhealing diabetic foot ulcers (DFUs) are a serious complication of diabetes and are further exacerbated by bacterial colonization. The microbial burden in the wound of each individual displays diverse morphological and physiological characteristics with unique patterns of host-pathogen interactions, antibiotic resistance, and virulence. Treatment involves empirical decisions until definitive results on the causative wound pathogens and their antibiotic susceptibility profiles are available. Hence, there is a need for rapid and accurate detection of these polymicrobial communities for effective wound management. Deciphering microbial communities will aid clinicians to tailor their treatment specifically to the microbes prevalent in the DFU at the time of assessment. This may reduce DFUs associated morbidity and mortality while impeding the rise of multidrug-resistant microbes.

Application and Clinical Effectiveness of Antibiotic-Loaded Bone Cement to Promote Soft Tissue Granulation in the Treatment of Neuropathic Diabetic Foot Ulcers Complicated by Osteomyelitis: A Randomized Controlled Trial

“…In our study population, the bacteriological analysis at baseline revealed predominance of one aerobic Gram-positive coccus (S. aureus) and of two aerobic Gram-negative bacilli (P. aeruginosa and E. coli). These results relatively corroborate findings from other investigations [31][32][33][34][35]. Although Gram-negative bacilli as a group were most prevalent bacteria isolated in our study, S. aureus was the most predominant isolate, accounting for 61.12% and 55.56% of all microorganisms in control and study group, respectively.…”

“…Diabetic foot ulcers are more inclined to bacterial infections that usually spread rapidly and lead to irreversible clinical outcomes [29]. Studies indicate that Staphylococcus, Pseudomonas, and Escherichia are among the most prevalent genera that isolated pathogens from diabetic foot ulcers [30][31][32][33]. Based on clinical practice guidelines available, there have been no sound evidence of preferential choice regarding the effectiveness of antibiotic's type [1].…”

“…The selection for the most appropriate and effective antibiotic therapy always requires to define the specific causative pathogens, especially as more than one bacteria are often found to be at the core of diabetic foot infection [29]. The empirical treatment is initially based on wound severity since culturing and profiling the antibiotic sensitivity of wound-associated microbes is time-consuming [31]. In our study population, the bacteriological analysis at baseline revealed predominance of one aerobic Gram-positive coccus (S. aureus) and of two aerobic Gram-negative bacilli (P. aeruginosa and E. coli).…”

Factors related to the composition and diversity of wound microbiota investigated using culture-independent molecular methods: a scoping review

“…Followed diabetes mellitus, sex was the second most commonly reported factor, which was considered in three studies. The dominant bacteria in the female samples included Clostridiales (24), Burkholderia, and Proteus (25). Actinomycetales was dominant in the males' wound samples (24).…”

“…Firmicutes in tissue samples were more abundant in the grade 0-2 group whereas Bacteroidetes, Prevotella, Peptoniphilus, Porphyromonas, and Dialister were more abundant in the grade 3-5 group (22). The DFUs in the grade 5 group were relatively more diverse than in the other wound grades (25). Other factors included recurrent ulcers (20), metabolite concentrations in wounds (36), and slough (34), all of which were reported in a single study.…”