Microbiology of diabetic foot infections: from Louis Pasteur to 'crime scene investigation'

Studying Microbial Ecology of Diabetic Foot Infections: Significance of PCR Analysis for Prudent Antimicrobial Stewardship

This study presents a comprehensive investigation into the microbial ecology of diabetic foot infections (DFIs), using molecular-polymerase chain reaction (PCR) analysis to accurately identify the causative agents. One hundred DFI patients were recruited and classified using the Depth Extent Phase and Associated Etiology (DEPA) score according to their severity. Results revealed polymicrobial infections in 75% of cases, predominantly featuring Staphylococcus epidermidis (83%) and Staphylococcus aureus (63%). Importantly, 20% of samples exhibited facultative anaerobes Bacteroides fragilis or Clostridium perfringens, exclusively in high DEPA score ulcers. Candida albicans coinfection was identified in 19.2% of cases, underscoring the need for mycological evaluation. Empirical antimicrobial therapy regimens were tailored to DEPA severity, yet our findings highlighted a potential gap in methicillin-resistant Staphylococcus aureus (MRSA) coverage. Despite an 88% prevalence of methicillin-resistant Staphylococci, vancomycin usage was suboptimal. This raises concerns about the underestimation of MRSA risk and the need for tailored antibiotic guidelines. Our study demonstrates the efficacy of molecular-PCR analysis in identifying diverse microbial communities in DFIs, influencing targeted antibiotic choices. The results advocate for refined antimicrobial guidelines, considering regional variations in microbial patterns and judiciously addressing multidrug-resistant strains. This research contributes crucial insights for optimizing DFIs management and helps the physicians to have a fast decision in selection the suitable antibiotic for each patient and to decrease the risk of bacterial resistance from the improper use of broad-spectrum empirical therapies.

Targeting Anaerobic Respiration in Pseudomonas aeruginosa with Chlorate Improves Healing of Chronic Wounds

Objective: Pseudomonas aeruginosa is an opportunistic pathogen that can establish chronic infections and form biofilm in wounds. Because the wound environment is largely devoid of oxygen, P. aeruginosa may rely on anaerobic metabolism, such as nitrate respiration, to survive in wounds. While nitrate reductase (Nar) typically reduces nitrate to nitrite, it can also reduce chlorate to chlorite, which is a toxic oxidizing agent. Therefore, chlorate can act as a prodrug to specifically eradicate hypoxic/anoxic, nitrate-respiring P. aeruginosa populations, which are often tolerant to conventional antibiotic treatments. Approach: Using a diabetic mouse model for chronic wounds, we tested the role that anaerobic nitrate respiration plays in supporting chronic P. aeruginosa infections. Results: P. aeruginosa forms biofilm deep within the wound where the environment is anoxic. Daily treatment of P. aeruginosa-infected wounds with chlorate supported wound healing. Chlorate treatment was as effective as a treatment with ciprofloxacin (a conventional antibiotic that targets both oxic and hypoxic/anoxic P. aeruginosa populations). Chlorate-treated wounds showed markers of good-quality wound healing, including well-formed granulation tissue, reepithelialization and microvessel development. Loss- and gain-of-function experiments showed that P. aeruginosa requires nitrate respiration to establish a chronic wound infection and form biofilms. Innovation: We show that the small molecule chlorate, kills the opportunistic pathogen, P. aeruginosa, by targeting a form of anaerobic metabolism called nitrate respiration. Conclusion: Chlorate holds promise as a treatment to combat diverse bacterial infections where oxygen is limiting and/or where pathogens grow as biofilms because many other pathogens possess Nar and survive using anaerobic metabolism.

A Systematic Review of the Microbial Landscape of Diabetic Foot Ulcers in Uganda

Background

Diabetes is a growing health concern globally. Poorly managed diabetes may result in diabetic foot ulcers (DFU), which can become a source of chronic infection known as diabetic foot infections. The increasing trend of diabetes in Uganda speaks to the potential for diabetic foot ulcers which may eventually become infected and their attendant impact on the quality of life of diabetic patients. This review assesses the microbial diversity of DFUs in Uganda, aiming to guide treatment and identify research gaps.

Main Body of the Abstract

We searched PubMed, Scopus and Embase for studies conducted in Uganda that reported isolating microorganisms from diabetic foot ulcers. Following the preferred reporting items for systematic reviews and meta-analysis (PRISMA), we included two eligible studies that reported isolating 122 bacteria spread across eleven (11) species using swab samples and conventional culture methods. Significant isolates included World Health Organization priority pathogens including: Enterobacter specie, Staphylococcus aureus, Klebsiella pneumoniae, and Acinetobacter specie. Methicillin resistant Staphylococcus aureus (MRSA) constituted 33.3% of Staphylococci species and 26% of all bacterial isolates while extended-spectrum beta-lactamase producing Escherichia coli and Klebsiella specie constituted 14.29% of total microbial isolates. Most bacteria showed susceptibility to Imipenem, Vancomycin, Ciprofloxacin, and Clindamycin, but resistance to Cotrimoxazole and Ampicillin was noted.

Short Conclusion

We conclude that data on the microbiology of DFUs in Uganda is scarce; however, the bioburden of DFUs in the country is similar to those in other parts of the world, and MRSA poses a challenge to antibiotic therapy. Consequently, the continued use of swab samples and conventional culture and sensitivity methods may limit the isolation, identification, and presentation of other important isolates. We recommend characterization of bacterial isolates to better understand their genetic makeup, and the development of a national guideline for managing diabetic foot infections.

Whole genome sequencing and pan-genome analysis of Staphylococcus/Mammaliicoccus spp. isolated from diabetic foot ulcers and contralateral healthy skin of Algerian patients

BACKGROUND

Diabetic foot infections (DFIs) are the most common complications of diabetic foot ulcers (DFUs), and a significant cause of lower extremity amputation. In this study we used whole genome sequencing to characterize the clonal composition, virulence and resistance genetic determinants of 58 Staphylococcus/Mammaliicoccus spp. isolates from contralateral healthy skin and DFU from 44 hospitalized patients.

RESULTS

S. aureus (n = 32) and S. epidermidis (n = 10) isolates were recovered from both DFUs and healthy skin, whereas, S. haemolyticus (n = 8), M. sciuri (n = 1), S. hominis (n = 1) and S. simulans (n = 3) were recovered exclusively from healthy skin. In contrast, S. caprae (n = 2) and S. saprophyticus (n = 1) were recovered only from DFUs. Among S. aureus isolates, MRSA were present with high prevalence (27/32, 84.4%), 18 of which (66.7%) were from DFUs and 9 (33.3%) from healthy skin. In contrast, the coagulase-negative Staphylococcus (CoNS)/Mammaliicoccus isolates (n = 26), in particular S. epidermidis and S. haemolyticus were more prevalent in healthy skin, (10/26, 38.5%) and (8/26, 30.8%), respectively. MLST, spa and SCCmec typing classified the 32 S. aureus isolates into 6 STs, ST672, ST80, ST241, ST1, ST97, ST291 and 4 unknown STs (STNF); 8 spa types, t044, t037, t3841, t1247, t127, t639, t937 and t9432 and 2 SCCmec types, type IV and type III(A). Among CoNS, the S. epidermidis isolates belonged to ST54, ST35 and ST640. S. haemolyticus belonged to ST3, ST25, ST29, ST1 and ST56. The sole M. sciuri isolate was found to carry an SCCmec type III(A). A wide range of virulence genes and antimicrobial resistance genes were found among our isolates, with varying distribution between species or STs. The pan-genome analysis revealed a highly clonal population of Staphylococcus isolates, particularly among S. aureus isolates. Interestingly, the majority of S. aureus isolates including MRSA, recovered from the healthy skin and DFUs of the same patient belonged to the same clone and exhibited similar virulence/resistance genotype.

CONCLUSIONS

Our study provides clinically relevant information on the population profile, virulence and antibiotic resistance of Staphylococcus/Mammaliicoccus spp. in DFIs, which could serve as a basis for further studies on these as well as other groups of pathogens associated with DFIs.

Quantitative Imaging of the Action of vCPP2319, an Antimicrobial Peptide from a Viral Scaffold, against Staphylococcus aureus Biofilms of a Clinical Isolate

The formation of biofilms is a common virulence factor that makes bacterial infections difficult to treat and a major human health problem. Biofilms are bacterial communities embedded in a self-produced matrix of extracellular polymeric substances (EPS). In this work, we show that vCPP2319, a polycationic peptide derived from the capsid protein of Torque teno douroucouli virus, is active against preformed Staphylococcus aureus biofilms produced by both a reference strain and a clinical strain isolated from a diabetic foot infection, mainly by the killing of biofilm-embedded bacteria. The direct effect of vCPP2319 on bacterial cells was imaged using atomic force and confocal laser scanning microscopy, showing that the peptide induces morphological changes in bacterial cells and membrane disruption. Importantly, vCPP2319 exhibits low toxicity toward human cells and high stability in human serum. Since vCPP2319 has a limited effect on the biofilm EPS matrix itself, we explored a combined effect with α-amylase (EC 3.2.1.1), an EPS matrix-degrading enzyme. In fact, α-amylase decreases the density of S. aureus biofilms by 2.5-fold. Nonetheless, quantitative analysis of bioimaging data shows that vCPP2319 partially restores biofilm compactness after digestion of the polysaccharides, probably due to electrostatic cross-bridging of the matrix nucleic acids, which explains why α-amylase fails to improve the antibacterial action of the peptide.

Multi-Instrumental Analysis Toward Exploring the Diabetic Foot Infection Microbiota

The polymicrobial nature of diabetic foot infection (DFI) makes accurate identification of the DFI microbiota, including rapid detection of drug resistance, challenging. Therefore, the main objective of this study was to apply matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI TOF MS) technique accompanied by multiply culture conditions to determine the microbial patterns of DFIs, as well as to assess the occurrence of drug resistance among Gram-negative bacterial isolates considered a significant cause of the multidrug resistance spread. Furthermore, the results were compared with those obtained using molecular techniques (16S rDNA sequencing, multiplex PCR targeting drug resistance genes) and conventional antibiotic resistance detection methods (Etest strips). The applied MALDI-based method revealed that, by far, most of the infections were polymicrobial (97%) and involved many Gram-positive and -negative bacterial species-19 genera and 16 families in total, mostly Enterobacteriaceae (24.3%), Staphylococcaceae (20.7%), and Enterococcaceae (19.8%). MALDI drug-resistance assay was characterized by higher rate of extended-spectrum beta-lactamases (ESBLs) and carbapenemases producers compared to the reference methods (respectively 31% and 10% compared to 21% and 2%) and revealed that both the incidence of drug resistance and the species composition of DFI were dependent on the antibiotic therapy used. MALDI approach included antibiotic resistance assay and multiply culture conditions provides microbial identification at the level of DNA sequencing, allow isolation of both common (eg. Enterococcus faecalis) and rare (such as Myroides odoratimimus) bacterial species, and is effective in detecting antibiotic-resistance, especially those of particular interest-ESBLs and carbapenemases.

Genome editing for phage design and uses for therapeutic applications

The over usage of antibiotics leads to antibiotic abuse which in turn eventually raises resistance mechanisms among wide range of pathogens. Due to lack of experimental data of efficacy of phages as potential antimicrobial and therapeutic agent and also more specific and cumbersome isolation process against specific pathogens makes it not so feasible technology to be looked as an alternative therapy. But, recent developments in genome editing techniques enables programmed nuclease enzymes that has effectively improvised our methodology to make accurate changes in the genomes of prokaryote as well as eukaryote cells. It is already strengthening our ability to improvise genetic engineering to disease identification by facilitating the creation of more precise models to identify the root cause. The present chapter discusses on improvisation of phage therapy using recent genome editing tools and also shares data on the methods of usage of phages and their derivatives like proteins and enzymes such as lysins and depolymerases, as a potential therapeutic or prophylaxis agent. Methods involved in recombinant based techniques were also discussed in this chapter. Combination of traditional approach with modern tools has led to a potential development of phage-based therapeutics in near future.

Vitamin K3 (Menadione) is a multifunctional microbicide acting as a photosensitizer and synergizing with blue light to kill drug-resistant bacteria in biofilms

Cutaneous bacterial wound infections typically involve gram-positive cocci such as Staphylococcus aureus (SA) and usually become biofilm infections. Bacteria in biofilms may be 100-1000-fold more resistant to an antibiotic than the clinical laboratory minimal inhibitory concentration (MIC) for that antibiotic, contributing to antimicrobial resistance (AMR). AMR is a growing global threat to humanity. One pathogen-antibiotic resistant combination, methicillin-resistant SA (MRSA) caused more deaths globally than any other such combination in a recent worldwide statistical review. Many wound infections are accessible to light. Antimicrobial phototherapy, and particularly antimicrobial blue light therapy (aBL) is an innovative non-antibiotic approach often overlooked as a possible alternative or adjunctive therapy to reduce antibiotic use. We therefore focused on aBL treatment of biofilm infections, especially MRSA, focusing on in vitro and ex vivo porcine skin models of bacterial biofilm infections. Since aBL is microbicidal through the generation of reactive oxygen species (ROS), we hypothesized that menadione (Vitamin K3), a multifunctional ROS generator, might enhance aBL. Our studies suggest that menadione can synergize with aBL to increase both ROS and microbicidal effects, acting as a photosensitizer as well as an ROS recycler in the treatment of biofilm infections. Vitamin K3/menadione has been given orally and intravenously worldwide to thousands of patients. We conclude that menadione/Vitamin K3 can be used as an adjunct to antimicrobial blue light therapy, increasing the effectiveness of this modality in the treatment of biofilm infections, thereby presenting a potential alternative to antibiotic therapy, to which biofilm infections are so resistant.

Interspecies interactions in mixed-species biofilms formed by Enterococcus faecalis and gram-negative bacteria isolated from polymicrobial diabetic foot ulcers

Diabetic foot ulcers (DFU) are exacerbated by bacterial colonisation. Here, a high prevalence of Enterococcus faecalis was observed in DFU patients from an Argentinean hospital. E. faecalis was frequently co-isolated with Escherichia coli, Morganella morganii, and Pseudomonas aeruginosa. The effect of interspecies interactions on bacterial growth was investigated in mixed-species macrocolony biofilms developed in Lubbock-Glc-agar. Similar cell counts were found for E. faecalis and M. morganii growing in mixed and single-species biofilms. An E. faecalis strain showed 1 Log higher cell counts in mixed biofilms with E. coli. Remarkably, E. faecalis strains showed 2 to 4 Log higher cell counts in mixed biofilms with P. aeruginosa. This effect was not observed in planktonic growth or biofilms developed in tryptic soy agar. The present findings reveal bacterial interactions that benefit E. faecalis in mixed-species biofilms, mainly with P. aeruginosa, in a medium that partially mimics the nutrients found in DFU.

Distribution of Causative Microorganisms in Diabetic Foot Infections: A Ten-Year Retrospective Study in a Tertiary Care Hospital in Central Malaysia

Diabetes mellitus is a global pandemic, especially in Southeast Asia. Diabetic foot infection (DFI) is a common complication of this condition and causes significant morbidity and mortality in those affected. There is a lack of locally published data on the types of microorganisms and empirical antibiotics being prescribed. This paper highlights the importance of local microorganism culture and antibiotic prescription trends among diabetic foot patients in a tertiary care hospital in central Malaysia. This is a retrospective, cross-sectional study of data taken from January 2010 to December 2019 among 434 patients admitted with diabetic foot infections (DFIs) using the Wagner classification. Patients between the ages of 58 and 68 years old had the highest rate of infection. Pseudomonas Aeruginosa, Proteus spp., and Proteus mirabilis appeared to be the most isolated Gram-negative microorganisms, and Staphylococcus aureus, Streptococcus agalactiae, and MRSA appeared to be the most common Gram-positive microorganisms. The most common empirical antibiotics prescribed were ampicillin/sulbactam, followed by ciprofloxacin and ceftazidime, and the most common therapeutic antibiotics prescribed were ampicillin/sulbactam, ciprofloxacin, and cefuroxime. This study could be immensely pertinent in facilitating future empirical therapy guidelines for treating diabetic foot infections.

Colonizing microbiota is associated with clinical outcomes in diabetic wound healing

With the development of society and the improvement of life quality, more than 500 million people are affected by diabetes. More than 10 % of people with diabetes will suffer from diabetic wounds, and 80 % of diabetic wounds will reoccur, so the development of new diabetic wound treatments is of great importance. The development of skin microbe research technology has gradually drawn people's attention to the complex relationship between microbes and diabetic wounds. Many studies have shown that skin microbes are associated with the outcome of diabetic wounds and can even be used as one of the indicators of wound prognosis. Skin microbes have also been found to have the potential to treat diabetic wounds. The wound colonization of different bacteria can exert opposing therapeutic effects. It is necessary to fully understand the skin microbes in diabetic wounds, which can provide valuable guidance for clinical diabetic wound treatment.

Polymeric/Dextran Wafer Dressings as Promising Long-Acting Delivery Systems for Curcumin Topical Delivery and Enhancing Wound Healing in Male Wistar Albino Rats

Curcumin is the main active constituent in turmeric, and it is one of the biopolyphenolic compounds. A cumulative body of research supports the use of curcumin in the treatment of wounds, yet poor water solubility and lack of therapeutic dose determination hamper its use for this therapeutic purpose. This work aimed at preparing novel curcumin wafer dressings to provide a favorable environment for wound healing. Hybrid synthetic (PVA, PVP, HPMC, and CMC) and biodegradable (sodium alginate and dextran) polymers were employed to prepare wafer dressings loaded with incremental three doses (2, 10, and 20 mg) of curcumin per a wafer dressing. The solvent casting method was used to prepare the dressings. Dimension, surface pH, mechanical properties, DSC, FTIR, XRD, erosion time, and in vitro release were studied. Skin wound healing assay was studied in Wistar albino rats. Six curcumin-loaded wafers were successfully prepared with good mechanical properties. Curcumin was dispersed in an amorphous/molecular form, as evidenced by thermal (DSC) and spectral (FTIR and XRD) analyses. Prolonged curcumin release (>24 h) was recorded for F6 (10 mg curcumin) and F7 (20 mg curcumin). Wound healing rate constants and time for 50% wound closure (T1/2) were estimated from a semi-log wound diameter versus time curve. A superior healing rate (up to 3-fold faster) was recorded for curcumin-loaded wafer dressings containing 10 mg (F6) with T1/2 of 7 days compared to 20 days for the placebo-treated group. These results warrant using the selected curcumin-loaded wafer dressing for safer and faster wound closure.

Bacteriophage therapy as an alternative technique for treatment of multidrug-resistant bacteria causing diabetic foot infection

Diabetic foot ulcer (DFU) represented the most feared diabetic complication that caused the hospitalization of the diabetic patient. DFU was usually characterized with delayed healing as the diabetic neuropathy, angiopathy, and ulcer concomitant infections, among them, are multidrug-resistant (MDR) bacteria that emphasized the clinical importance for developing new therapeutic strategy with safe and effective alternatives for the antibiotics to overcome DFU-MDR bacterial infection. Bacteriophage therapy was considered a novel approach to eradicate the MDR, but its role in the polymicrobial infection of the DFU remains elusive. Thus, the current work was designed to investigate the effect of the topical application of the phage cocktail on the healing of the diabetic wound infected with clinical isolates of Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella variicola, Escherichia coli, and Proteus mirabilis. Bacterial isolation was performed from clinical hospitalized and non-hospitalized cases of DFU, identified morphologically, biochemically, molecularly via 16 s rRNA sequencing, and typed for the antibiotic resistance pattern. Moreover, phages were isolated from the aforementioned clinical isolates and identified with electron microscope. Forty-five adult male Sprague–Dawley rats were assigned in 3 groups (15 rats each), namely, the diabetic infected wound group, diabetic infected wound ceftriaxone-treated group, and the diabetic infected wound phage cocktail-treated group. The results revealed that phage cocktail had a superior effect over the ceftriaxone in wound healing parameters (wound size, wound index, wound bacterial load, and mRNA expression); wound healing markers (Cola1a, Fn1, MMP9, PCNA, and TGF-β); inflammatory markers (TNF-α, NF-κβ, IL-1β, IL-8, and MCP-1); anti-inflammatory markers (IL-10 and IL-4); and diabetic wound collagen deposition; and also the histomorphic picture of the diabetic infected wound. Based on the current findings, it could be speculated that phage therapy could be considered a novel antibiotic substitute in the DFU with MDR-polymicrobial infection therapeutic strategies.

Microbiota of diabetic foot infections in a University Hospital in Bogotá, Colombia

The presence of infection in diabetic foot ulcers (DFU) is one of the main causes of lower limb amputation in the world. The presence of polymicrobial infections is usually the standard for isolation in such lesions, with Gram Positive (GP) germs being the main organisms involved, as is described in the global literature. However, some studies indicate a greater number of isolates with Gram Negative (GN) germs, reported mainly in the literature of Middle Eastern countries and in the tropics.

Metagenomics of diabetic foot ulcer undergoing treatment with total contact casting: a case study

OBJECTIVE

Diabetic foot ulcers (DFUs) are characterised by the presence of many microbes, some of which may not be identified by traditional culture techniques. Total contact casting (TCC) remains the gold-standard for offloading, yet little is known about the microbiome of wounds that progress from hard-to-heal to closed within a TCC.

METHOD

A patient with a DFU underwent weekly treatment with TCC to closure. Samples for next-generation sequencing (NGS) and bioinformatics analysis of tissue samples were collected during each visit. Detection, identification, characterisation of the microbial community and abundance of microbes in each sample were compared.

RESULTS

Abundance of microbes, identified by species and strain, changed with each treatment visit. By the final week of treatment, species diversity of the wound microbiome had decreased significantly, highlighted by an observed decrease in the number of total microorganisms present. Resistance genes for tetracyclines were detected in the first sample, but not in subsequent samples.

CONCLUSION

The results of this study suggest dynamic microbiological changes associated with DFUs as they progress to healing within a TCC. As NGS becomes more readily available, further studies will be helpful to gain an improved understanding of the significance of the wound microbiome in patients with DFUs.

Evaluation of Polymerase Chain Reaction in the Identification and Quantification of Clinically Relevant Bacterial Species in Lower Extremity Wound Infections

Identification of bacteria by polymerase chain reaction (PCR) is known to be more sensitive than culture, which brings to question the clinical applicability of the results. In this study, we evaluate the ability of PCR to detect clinically relevant bacterial species in lower extremity wound infections requiring operative debridement, as well as the quantitative change in biodiversity and bacterial load reflected by PCR during the course of treatment. Thirty-four infected lower extremity were examined by analysis of 16S ribosomal RNA subunit and by culture. McNemar's test was used to measure the concordance of clinically relevant bacterial species identified by PCR compared to culture during each debridement. Change in wound biodiversity from initial presentation to final closure was evaluated by Wilcoxon signed-rank test. Kaplan-Meier survival curve was used to characterize change in measured bacterial load over the course of operative debridement. A total of 15 and 12 clinically relevant bacterial species were identified by PCR and culture, respectively. The most common bacterial species identified were Coagulase-negative Staphylococcus, Staphylococcus aureus, and Enterococcus spp. PCR was less likely to detect Enterococcus spp. on initial debridement and Coagulase-negative Staphylococcus on closure in this study population. A significant decrease in mean number of clinically relevant species detected from initial debridement to closure was reflected by culture (p = .0188) but not by PCR (p = .1848). Both PCR (p = .0128) and culture (p = .0001) depicted significant reduction in mean bacterial load from initial debridement to closure. PCR is able to identify common clinically relevant bacterial species in lower extremity surgical wound infections. PCR displays increased sensitivity compared to culture with relation to detection of biodiversity, rather than bacterial load. Molecular diagnostics and conventional culture may serve a joint purpose to assist with rendering clinical judgment in complex wound infections.

Neuropathic ulcers in leprosy: clinical features, diagnosis and treatment

Leprosy is a neglected disease caused by Mycobacterium leprae and Mycobacterium lepromatosis, and is related to significant disabilities resulting from the neural damage generated by this mycobacteria. Neuropathic ulcers-lesions that can appear at the plantar and extra-plantar levels-are one such disability, and diagnosis requires an adequate dermatological, neurological and microbiological evaluation. The treatment of these lesions is based on a multidisciplinary approach that includes debridement of the necrotic tissue, controlling infections, reducing pressure areas, optimising blood flow, and nerve decompression. This review aims to describe the clinical features, diagnostic methods and treatment of neuropathic ulcers in leprosy. The diagnostic methods and medical management used in leprosy ulcers are based on those used for diabetic foot. This requires radical change as these diseases are immunologically and physiologically very different.

Screening of Natural Molecules as Adjuvants to Topical Antibiotics to Treat Staphylococcus aureus from Diabetic Foot Ulcer Infections

Diabetic foot ulcers (DFUs) are a common result of a complex secondary complication of diabetes mellitus. More than half of DFUs become infected due to frequent colonization with Staphylococcus aureus. The use of topical antibiotics is proposed, especially in combination with natural adjuvants, to minimize the negative impacts caused by generalized use of systemic antibiotics. In this study, 13 different phytochemicals—namely chalcone, juglone, cinnamic acid, trigonelline, Furvina—and four nitrovinylfuran derivatives—guaiazulene, α-bisabolol, farnesol and nerolidol—were selected to be tested as antibiotic enhancers. After minimum inhibitory and bactericidal concentration (MIC and MBC) determination of each molecule against different strains of S. aureus, including clinical isolates from diabetic foot wounds (CECT 976, Xu212, SA 1199B, RN4220, MJMC102, MJMC109, MJMC110 and MJMC111), their potentiation effects on the antibiotics fusidic acid, mupirocin, gentamicin, oxacillin and methicillin were evaluated through the disc diffusion method. Farnesol at sub-MIC was able to restore the activity of methicillin and oxacillin on the MJMC102 and MJMC111 strains, as well as two MRSA clinical isolates, and potentiated the effect of the remaining antibiotics. The results obtained demonstrate the great potential for the topical application of phytochemicals and derivatives as antibiotic resistance modifier agents to combat multidrug resistance in bacterial wound infections.

Multifaceted Strategy Improves Outcomes of Patients Hospitalized with a Diabetic Foot Infection

Diabetic foot infections (DFIs) are associated with major morbidity, reduced quality of life and increased mortality. Osteomyelitis is a leading cause of lower-extremity amputation in diabetic patients. We aimed to examine whether a multifaceted strategy for treating hospitalized patients with a DFI effectively influenced microbiological culture results and outcomes. A retrospective cohort-study in a 1100-bed, tertiary-care university hospital was conducted. Adult patients with a DFI admitted to the orthopedics department between 2015 and 2019 were included. During the pre-intervention period (2015-2016), one general orthopedic department was in operation. In the post-intervention period (2017-2019), a second department was created with a designated "complicated wound unit". The multifaceted strategy included revising local guidelines for DFI culturing emphasizing bone cultures, correct sample handling, and adjusting antibiotic treatment to culture results. Additionally, a weekly multidisciplinary-team grand round was instigated and post-discharge outpatient follow-up was scheduled. 652 patients with DFIs were included; 101 during the pre-intervention period and 551 during the post-intervention period. Compared to the pre-intervention, during the post-intervention period mainly bone or deep-tissue cultures were performed (9.7% vs. 98.2%, P < 0.001). Bacteriology cultures in the pre-intervention versus post-intervention period revealed: among staphylococcus isolates, fewer methicillin-resistant Staphylococcus aureus detected (20.4% vs. 9.8%, P = 0.010); within Enterobacteriaceae isolates, fewer extended-spectrum β-lactamase producing bacteria detected (51.6% vs. 23.6%, P < 0.001); a decrease in Pseudomonas aeruginosa isolates (28% vs. 10.6%, P < 0.001) and an increase in anaerobic bacterial isolates (0 vs. 11.1%, P < 0.001). On multivariate regression, the post-intervention period (ie multifaceted strategy) was a protective measure against readmissions (P = 0.007 OR 0.50 95% CI 0.30-0.82). We conclude that our interventive multifaceted strategy led to accurate bacterial diagnosis, de-escalation of antibiotic treatment and readmission reduction.

Evaluation of Glycologic Point-of-Care Infection Test Kit for Diabetic Foot Ulcers in Relation to Bacterial Presence: A Prospective Cohort Study

BACKGROUND

Point-of-care testing for infection might help podiatric physicians optimize management of diabetic foot ulcers (DFUs). Glycologic's proprietary GLYWD product has been developed to detect changes in a patient's immunologic/inflammatory response related to wound infection. We evaluated how bacterial presence in DFUs relates to GLYWD test outcome.

METHODS

This was a single-organization, prospective, controlled cohort study of clinical opinion versus GLYWD test result for DFU infection status and the appraisal of bacterial presence in the wounds and semiquantitative microbiology swab at weeks 0, 3, 6, 12, and 18. Spearman correlation, backward elimination linear regression, and principal components analysis were applied to determine which variables, including degree of bacterial load, are associated with a positive clinical opinion or GLYWD result for DFU infection.

RESULTS

Forty-eight patients were enrolled, and 142 complete wound appraisals were conducted; a consensus outcome between clinical opinion and GLYWD result was achieved in most (n = 122, 86%). Clinical opinion significantly correlated with a higher bacterial load (Spearman rho = 0.38; P < .01), whereas GLYWD did not (rho = -0.010; P = .91). This observation was corroborated with logistic regression analysis, in which a previous observation of both clinical opinion and GLYWD associating with wound purulence and erythema was also confirmed.

CONCLUSIONS

Podiatric physicians are guided by hallmark signs of DFU infection, such as erythema and purulence; furthermore, we found that clinical opinion of infection correlates with increased bacterial load. GLYWD test results match clinical opinion in most cases, although the results obtained with this point-of-care method suggest that the degree of bacterial presence might not necessarily mean a higher chance of inducing an immunologic/inflammatory host response to said bacteria.

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.

Aerobic bacteria isolated from diabetic foot ulcers of Egyptian patients: types, antibiotic susceptibility pattern and risk factors associated with multidrug-resistant organisms

INTRODUCTION

Diabetic foot infection (DFI) is one of the common diabetic complications. Pathogens causing DFI and their antibiotic susceptibility vary with location. Therefore, empirical antibiotic therapy should be based on the pathogens that are most likely to be present. Aim: To identify the frequent aerobic bacteria causing DFI with detection of their antibiotic susceptibility to help clinicians in our community choose the best empirical antibiotic for DFI.

METHODS

Swabs were collected from 104 diabetic foot ulcers (DFUs). Aerobic bacterial cultures were done followed by bacterial identification and antibiotic susceptibility testing on VITEK® 2 system. Extended-spectrum beta-lacatamase (ESBL) detection was performed phenotypically and confirmed by multiplex-PCR for bla _CTX-M, bla _TEM, and bla _SHV genes.

RESULTS

Aerobic bacterial infection was detected in 82/104 (78.8%) of the DFUs. Gram-negative bacilli (GNB) were isolated more frequently (56.1%) than Gram-positive cocci (GPC) (43.9%). The most common single-isolated bacteria were K. pneumoniae (26.8%), S. aureus and coagulase negative staphylococci (22% for each). The only significant independent predictors of DFI with GNB or GPC were long DM duration and frequent hospitalizations, respectively. The most active antibiotics were amikacin, tigecycline and meropenem for GNB, and linezolid and vancomycin for staphylococci. Multidrug-resistance prevalence was 95.1%. ESBL was detected in 52.6% of Enterobacteriaceae; the bla _CTX-M gene was the most common (90%), followed by bla _TEM (65%) and bla _SHV (35%). Peripheral neuropathy was the single independent predictor for DFI with ESBL producers (adjusted OR=15.5).

CONCLUSIONS

There is a notable local pattern of DFI bacteriology in our community. Our findings could be valuable in developing the future empirical treatment guidelines for DFIs.

Diabetic Foot Ulcer Infections and Pseudomonas aeruginosa Biofilm Production During the COVID-19 Pandemic

During the different waves of the coronavirus (COVID-19) pandemic, there has been an increased incidence of diabetes mellitus and diabetic foot infections. Among gram-negative bacteria, Pseudomonas aeruginosa is the predominant causative agent for diabetic foot ulcer infections in low-resource countries. P. aeruginosa possesses a variety of virulence factors, including biofilm formation. Biofilm formation is an important benchmark characteristic in the pathophysiology of diabetic foot ulceration. The main objective of the current study was to identify the most commonly isolated organisms and their antibiotic susceptibility patterns in diabetic foot patients during the COVID-19 pandemic. We also determined the genes associated with bacterial persistence and biofilm formation in the predominantly isolated organism. Accordingly, 100 wound swab samples were collected from diabetic foot patients from different hospitals in Alexandria, Egypt. Through phenotypic detection of biofilm formation, 93% (40) of the 43 P. aeruginosa isolates examined were categorized as biofilm producers. Molecular detection of the biofilm-encoding genes among the 43 P. aeruginosa isolates was as follows: algD (100%), pelF (88%) and pslD (49.7%), and this highlights a need for biofilm formation inhibitors to prevent the persistence of bacterial pathogens, and thus achieve better clinical outcomes in diabetic foot ulcer infections.

Association of exposure to deoxynivalenol with DNA methylation in white blood cells in children in China

Deoxynivalenol (DON) is a mycotoxin that commonly contaminates cereals worldwide. Dietary exposure to DON is a subject of great public health concern, but studies on the health effects of chronic exposure to DON are not available. In this study, we investigated the connection between DNA methylation levels and DON exposure in children. The DNA methylation status of white blood cells from 32 children aged 2~15 years old in Henan, China, was profiled. A total of 378 differentially methylated CpGs were identified between the high and low DON exposure groups, and 8 KEGG pathways were found to be significantly enriched among the differentially methylated genes. In addition, the quantitative methylation of EIF2AK4, EMID2 and GNASAS was analysed using the Sequenom MassARRAY platform. The results showed that the methylation level of EIF2AK4 was significantly different between the two groups, and the methylation levels were associated with exposure to DON. Conclusively, our study found that chronic exposure to DON during childhood could affect DNA methylation levels.

Implementation of a clinical pharmacist-driven comprehensive medication management program in an outpatient wound healing center

BACKGROUND

The role of the pharmacist in wound healing management among patients with diabetic and nondiabetic foot ulcers (DFU) is unclear. We sought to implement and evaluate an integrated pharmacist-driven comprehensive medication management (CMM) program in a multidisciplinary podiatrist-led wound healing center (WHC).

OBJECTIVES

The objectives were to determine the role of the clinical pharmacist in a WHC and evaluate the impact of CMM interventions on prescribing rates and wound healing rates.

METHODS

A pharmacist-driven CMM program was implemented in a podiatrist-led WHC, and an evaluation spanning 6 years was conducted.

RESULTS

Overall, 1018 patients were treated over 6 years, and 515 received wound treatment after the CMM period, of which, 309 received CMM services. A total of 441 medication related problems (MRPs) were identified; most were related to medication safety (35.1%) and inappropriate or ineffective therapy (31.3%), and problems with adherence accounted for 22.5% of documented MRPs. An average of 3.41 interventions per patient were documented, and most were related to patient education (40.8%). Only metformin (20.3 vs. 34.2%; P < 0.001) and insulin prescription (57.3 vs. 73.8%; P < 0.001) prevalence increased after CMM implementation. Other prescriptions were not significantly different among patients presenting in the pre- and post-CMM periods, respectively. Wound healing rates among patients with DFU were similar before and after implementation (55 vs. 52%; P = 0.49). Likewise, wound healing rates among those with non-DFUs were similar before- and after implementation (56 vs. 53%; P = 0.56).

CONCLUSION

The implementation of a novel pharmacist-driven CMM program embedded within a multidisciplinary podiatrist-managed WHC provided the initial evidence of the potential benefits of providing pharmacist-driven CMM services to patients with lower extremity ulcers. Prospective studies of CMM in this patient population are needed.

The Profile of Microbiological Pathogens in Diabetic Foot Ulcers

Diabetic foot, a main complication of diabetes mellitus, renders the foot susceptible to infection, and may eventually lead to non-traumatic limb amputation due to the deterioration of diabetic foot ulcers (DFUs). Characterizing the pathogen spectrum and antibiotic susceptibility is critical for the effective treatment of DFUs. In the current study, the characteristics and antibiotic susceptibility of the pathogen spectrum were analyzed. Secretions from the DFUs of 102 patients were cultured, and dominant pathogens were identified by using test cards. Antibiotic susceptibility of dominant pathogens was assayed by the Kirby–Bauer assay. We found that the dominant pathogens varied with age, duration of diabetes, blood sugar control, and the initial cause of ulcers. Moreover, the dominant pathogens were susceptible to at least one antibiotic. However, the antibacterial efficacy of several commonly used antibiotics decreased from 2016 to 2019. Our study indicates that the identification of dominant pathogens and antibiotic susceptibility testing is essential for the treatment of DFUs with effective antibiotics, while the abuse of antibiotics should be strictly restrained to reduce the generation of antibiotic-resistant strains.

Diabetic foot infections: Profile and antibiotic susceptibility patterns of bacterial isolates in a tertiary care hospital of Oman

BACKGROUND

In diabetic foot infections (DFIs), the diversity of microbial profile and ever-changing antibiotic-resistance patterns emphasize accurate characterization of microbial profile and antibiotic susceptibility pattern. The aim of the study was to investigate the pathogens associated with DFI and their antibiotic susceptibility patterns.

MATERIALS AND METHODS

A cross-sectional retrospective study was conducted at a tertiary-care hospital, Oman. The socio-demographic and microbiological profile and antibiotic susceptibility patterns of pathogens isolated from patients with DFIs from January 2013 to December 2018 were reviewed. Quantitative and qualitative variables were expressed as mean ± standard deviation and percentages, respectively. A Chi-square test was used for testing the association between multidrug-resistant (MDR) organisms and variables.

RESULTS

In total, 233 isolates recovered from 133 clinical specimens with an average of 1.8 organisms per specimen were included in the study. Fifty-six and forty-four percent of specimens showed monomicrobial and polymicrobial growth of two or more organisms, respectively. The frequency of isolation was predominant among males (65%). Aerobic Gram-negative rods were predominantly (75%) isolated compared to Gram-positive organisms (25%). Staphylococcus aureus and Pseudomonas aeruginosa were the most frequently isolated Gram-positive and Gram-negative bacteria, respectively. Thirty-eight percent of them were MDR strains. Gram-negative organisms showed fairly good susceptibility ranging from 75% to 100% to carbapenems, aminoglycosides, and piperacillin-tazobactam. While doxycycline and trimethoprim-sulfamethoxazole showed good susceptibility toward Gram-positive organisms.

CONCLUSION

DFIs are often polymicrobial with a predominance of Gram-negative pathogens. This study recommends the use of carbapenems and doxycycline for empirical therapy of Gram-negative and Gram-positive bacterial DFIs, respectively.

Point-of-care testing for bacterial infection in diabetic foot ulcers: a prospective cohort study

OBJECTIVE

To appraise the performance of a new point-of-care wound infection detection kit in diabetic foot ulcers (DFUs), using clinician opinion as the primary comparator. The proprietary swab-based chromatic Glycologic (Glycologic Ltd., UK) detection kit used in this study is designed to detect host response to pathogenic levels of bacteria in wounds.

METHOD

In high-risk podiatry clinics, patients with DFUs were recruited and infection detection kit test results compared with initial clinician opinion. Chi-squared tests, principal component analysis (PCA) and multiple regression analysis were performed to determine which variables were possibly associated with infection. The variables considered were patients' wound parameters, wider vascular comorbidity and demographics.

RESULTS

A total of 136 patients, providing 383 wound swabs, were included in the study. Total agreement in terms of DFU wound assessment for infection-between podiatrists' clinical opinion and Glycologic kit test result-was observed in 79% of cases (301/383). For 56 of the 349 negative infection detection kit test results (16%), podiatrists identified a 'possible' or 'definite' infection. Conversely, in 14 of the 307 cases (4.6%) where podiatrists deemed the wound 'not infected', the infection detection kit test showed a colour change. Regression analysis and PCA showed that clinical signs of wound infection, namely erythema, purulence and odour, were all significantly associated with both a positive clinical opinion and infection detection kit test result. However, in the case of the infection detection kit, a patient's number of lesions and vascular comorbidities were also significantly correlated with a positive test result.

CONCLUSION

A host response to critical pathological levels of bioburden in a wound-as detected with the infection detection kit-may partly be determined by an individual patient's (vascular) health and therefore be person-specific. Further research is indicated to determine the relationship between an infection detection kit test result and the microbiological status of the wound.

The Effects of Antimicrobial Resistance and the Compatibility of Initial Antibiotic Treatment on Clinical Outcomes in Patients With Diabetic Foot Infection

We aimed to determine pathogen microorganisms, their antimicrobial resistance patterns, and the effect of initial treatment on clinical outcomes in patients with diabetic foot infection (DFI). Patients with DFI from 5 centers were included in this multicenter observational prospective study between June 2018 and June 2019. Multivariate analysis was performed for the predictors of reinfection/death and major amputation. A total of 284 patients were recorded. Of whom, 193 (68%) were male and the median age was 59.9 ± 11.3 years. One hundred nineteen (41.9%) patients had amputations, as the minor (n = 83, 29.2%) or major (n = 36, 12.7%). The mortality rate was 1.7% with 4 deaths. A total of 247 microorganisms were isolated from 200 patients. The most common microorganisms were Staphylococcus aureus (n = 36, 14.6%) and Escherichia coli (n = 32, 13.0%). Methicillin resistance rates were 19.4% and 69.6% in S aureus and coagulase-negative Staphylococcus spp., respectively. Multidrug-resistant Pseudomonas aeruginosa was detected in 4 of 22 (18.2%) isolates. Extended-spectrum beta-lactamase-producing Gram-negative bacteria were detected in 20 (38.5%) isolates of E coli (14 of 32) and Klebsiella spp. (6 of 20). When the initial treatment was inappropriate, Klebsiella spp. related reinfection within 1 to 3 months was observed more frequently. Polymicrobial infection (p = .043) and vancomycin treatment (p = .007) were independent predictors of reinfection/death. Multivariate analysis revealed vascular insufficiency (p = .004), hospital readmission (p = .009), C-reactive protein > 130 mg/dL (p = .007), and receiving carbapenems (p = .005) as independent predictors of major amputation. Our results justify the importance of using appropriate narrow-spectrum empirical antimicrobials because higher rates of reinfection and major amputation were found even in the use of broad-spectrum antimicrobials.

An investigation of conventional microbial culture for the Naja atra bite wound, and the comparison between culture-based 16S Sanger sequencing and 16S metagenomics of the snake oropharyngeal bacterial microbiota

Naja atra is a major venomous snake found in Taiwan. The bite of this snake causes extensive wound necrosis or necrotizing soft tissue infection. Conventional microbial culture-based techniques may fail to identify potential human pathogens and render antibiotics ineffective in the management of wound infection. Therefore, we evaluated 16S Sanger sequencing and next-generation sequencing (NGS) to identify bacterial species in the oropharynx of N. atra. Using conventional microbial culture methods and the VITEK 2 system, we isolated nine species from snakebite wounds. On the basis of the 16S Sanger sequencing of bacterial clones from agar plates, we identified 18 bacterial species in the oropharynx of N. atra, including Morganella morganii, Proteus vulgaris, and Proteus mirabilis, which were also present in the infected bite wound. Using NGS of 16S metagenomics, we uncovered more than 286 bacterial species in the oropharynx of N. atra. In addition, the bacterial species identified using 16S Sanger sequencing accounted for only 2% of those identified through NGS of 16S metagenomics. The bacterial microbiota of the oropharynx of N. atra were modeled better using NGS of 16S metagenomics compared to microbial culture-based techniques. Stenotrophomonas maltophilia, Acinetobacter baumannii, and Proteus penneri were also identified in the NGS of 16S metagenomics. Understanding the bacterial microbiota that are native to the oropharynx of N. atra, in addition to the bite wound, may have additional therapeutic implications regarding empiric antibiotic selection for managing N. atra bites.

Naja atra bites induce extensive wound necrotizing soft tissue infections in a substantial proportion of patients. Empiric antibiotic administration in snakebite patients is a common practice, but clinical reports indicate that this treatment was ineffective in preventing secondary infection given that the microbiota of the infected wound and oropharynx of the culprit snake were not properly established. In this study, only 9 species were detected in cobra bites using a conventional microbial culture method and the VITEK 2 system, whereas 18 species were detected in the cobra oropharynx using microbial culture-based 16S Sanger sequencing. Among these, Morganella morganii, Proteus vulgaris, and Proteus mirabilis were identified as common bacteria. Compared to microbial culture-based 16S Sanger sequencing, NGS-based 16S metagenomic sequencing detected more than 286 bacterial species. Stenotrophomonas maltophilia, Acinetobacter baumannii, and Proteus penneri only appeared with 16S metagenomic sequencing. These results suggest that NGS-based 16S metagenomic sequencing is a better tool for uncovering the bacterial microbiota of the N. atra oropharynx, which may help in developing a proper therapeutic strategy for patients with N. atra bites.

Characterization of staphylococci sampled from diabetic foot ulcer of Jordanian patients

AIMS

The aim of this study was to isolate and characterize staphylococcal isolates from diabetic foot ulcers (DFU) in Jordanian patients.

METHODS AND RESULTS

Selected aerobic pathogens recovered from DFU specimens and patients' nares with a focus on staphylococci were investigated. Antimicrobial susceptibilities and the prevalence of methicillin-resistant staphylococci (MRS) were determined. SCCmec types and toxigenic characteristics were analysed and spa typing was performed for methicillin-resistant Staphylococcus aureus (MRSA) isolates. The relationship between toxigenic characteristics of MRSA and the Wagner ulcer grading system was statistically analysed. A total number of 87 DFU patients were recruited for the study. The DFU cultures were polymicrobial. Members of the genus Staphylococcus were the most common among DFU-associated isolates found in 48·3% (n = 42) of all patients enrolled. Coagulase-negative staphylococci (CoNS) comprised 63·3% of staphylococci isolated from DFUs predominated by Staphylococcus epidermidis in both DFU (7·6%) and nares (39·2%). Staphylococcus aureus was isolated from DFUs and nares in 14·2 and 9·8%, respectively, while 93 and 70% of these isolates were MRSA. Most of MRSA carried SCCmec type IV (76·2%) while SCCmec elements were non-typeable in most methicillin resistant coagulase negative staphylococci (MR-CoNS) (61·9%). The most frequent MRSA spa type was t386 (23·8%). Most MRSA and MR-CoNS exhibited resistance towards aminoglycosides, fluoroquinolones and macrolides and susceptibility towards vancomycin, mupirocin and linezolid. No association was found between the possession of pvl, tst, sea and hlg toxins and Wagner ulcer grading system (P value >0·05).

CONCLUSIONS

This analysis of Jordanian DFU culture demonstrated its polymicrobial nature with predominance of Staphylococcus sp.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study is the first of its type to assess the microbiology of DFU among Jordanian patients. The results will help in the appropriate application of antimicrobial chemotherapy in the management of DFU.

Adaptation of Staphylococcus aureus in a Medium Mimicking a Diabetic Foot Environment

Staphylococcus aureus is the most prevalent pathogen isolated from diabetic foot infections (DFIs). The purpose of this study was to evaluate its behavior in an in vitro model mimicking the conditions encountered in DFI. Four clinical S. aureus strains were cultivated for 16 weeks in a specific environment based on the wound-like medium biofilm model. The adaptation of isolates was evaluated as follows: by Caenorhabditis elegans model (to evaluate virulence); by quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR) (to evaluate expression of the main virulence genes); and by Biofilm Ring test^® (to assess the biofilm formation). After 16 weeks, the four S. aureus had adapted their metabolism, with the development of small colony variants and the loss of β-hemolysin expression. The in vivo nematode model suggested a decrease of virulence, confirmed by qRT-PCRs, showing a significant decrease of expression of the main staphylococcal virulence genes tested, notably the toxin-encoding genes. An increased expression of genes involved in adhesion and biofilm was noted. Our data based on an in vitro model confirm the impact of environment on the adaptation switch of S. aureus to prolonged stress environmental conditions. These results contribute to explore and characterize the virulence of S. aureus in chronic wounds.

The Role of Oxidative Stress and Antioxidants in Diabetic Wound Healing

Foot ulcers are one of the most common and severe complication of diabetes mellitus with significant resultant morbidity and mortality. Multiple factors impair wound healing include skin injury, diabetic neuropathy, ischemia, infection, inadequate glycemic control, poor nutritional status, and severe morbidity. It is currently believed that oxidative stress plays a vital role in diabetic wound healing. An imbalance of free radicals and antioxidants in the body results in overproduction of reactive oxygen species which lead to cell, tissue damage, and delayed wound healing. Therefore, decreasing ROS levels through antioxidative systems may reduce oxidative stress-induced damage to improve healing. In this context, we provide an update on the role of oxidative stress and antioxidants in diabetic wound healing through following four perspectives. We then discuss several therapeutic strategies especially dietary bioactive compounds by targeting oxidative stress to improve wounds healing.

MRI nomenclature for musculoskeletal infection

The Society of Skeletal Radiology (SSR) Practice Guidelines and Technical Standards Committee identified musculoskeletal infection as a White Paper topic, and selected a Committee, tasked with developing a consensus on nomenclature for MRI of musculoskeletal infection outside the spine. The objective of the White Paper was to critically assess the literature and propose standardized terminology for imaging findings of infection on MRI, in order to improve both communication with clinical colleagues and patient care.A definition was proposed for each term; debate followed, and the committee reached consensus. Potential controversies were raised, with formulated recommendations. The committee arrived at consensus definitions for cellulitis, soft tissue abscess, and necrotizing infection, while discouraging the nonspecific term phlegmon. For bone infection, the term osteitis is not useful; the panel recommends using terms that describe the likelihood of osteomyelitis in cases where definitive signal changes are lacking. The work was presented virtually to SSR members, who had the opportunity for review and modification prior to submission for publication.

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

This study explored the clinical effectiveness of antibiotic-loaded bone cement on primary treatment of diabetic foot infection. This is a randomized controlled study, including thirty-six patients with diabetic foot ulcer complicated by osteomyelitis who had undergone treatment between May 2018 and December 2019. Patients were randomly divided into control group (group A) and study group (group B). Patients in the intervention group received antibiotic-loaded bone cement repair as primary treatment, while patients in the control group received conventional vacuum sealing draining treatment. Clinical endpoints were assessed and compared between the two groups, including wound healing time, wound bacterial conversion, NRS pain score, number of wound dressing changes, and average hospitalization time. All patients were followed up for a period of 12 months after discharge. Results show that compared with the control group, patients in the study group had significant difference in the number of patients for baseline pathogens eradication, short NRS pain score, hospital length of stay and cost, wound surface reduction, healing time, low rate of complications, and infection recurrence. Based on the findings, we conclude that antibiotic-loaded bone cement can be used for treatment of wound in patient with diabetic foot infection. It can help to control wound infections, shorten hospital length of stay, reduce medical cost, and relieve both doctors' and patients' burden. The application of antibiotic-loaded bone cement is suitable for diabetic wound with soft tissue infection or osteomyelitis.

The dynamic wound microbiome

BACKGROUND

Diabetic foot ulcers (DFUs) account for the majority of all limb amputations and hospitalizations due to diabetes complications. With 30 million cases of diabetes in the USA and 500,000 new diagnoses each year, DFUs are a growing health problem. Diabetes patients with limb amputations have high postoperative mortality, a high rate of secondary amputation, prolonged inpatient hospital stays, and a high incidence of re-hospitalization. DFU-associated amputations constitute a significant burden on healthcare resources that cost more than 10 billion dollars per year. Currently, there is no way to identify wounds that will heal versus those that will become severely infected and require amputation.

MAIN BODY

Accurate identification of causative pathogens in diabetic foot ulcers is a critical component of effective treatment. Compared to traditional culture-based methods, advanced sequencing technologies provide more comprehensive and unbiased profiling on wound microbiome with a higher taxonomic resolution, as well as functional annotation such as virulence and antibiotic resistance. In this review, we summarize the latest developments in defining the microbiology of diabetic foot ulcers that have been unveiled by sequencing technologies and discuss both the future promises and current limitations of these approaches. In particular, we highlight the temporal patterns and system dynamics in the diabetic foot microbiome monitored and measured during wound progression and medical intervention, and explore the feasibility of molecular diagnostics in clinics.

CONCLUSION

Molecular tests conducted during weekly office visits to clean and examine DFUs would allow clinicians to offer personalized treatment and antibiotic therapy. Personalized wound management could reduce healthcare costs, improve quality of life for patients, and recoup lost productivity that is important not only to the patient, but also to healthcare payers and providers. These efforts could also improve antibiotic stewardship and control the rise of "superbugs" vital to global health.

Biofilms in Diabetic Foot Ulcers: Significance and Clinical Relevance

Foot infections are the main disabling complication in patients with diabetes mellitus. These infections can lead to lower-limb amputation, increasing mortality and decreasing the quality of life. Biofilm formation is an important pathophysiology step in diabetic foot ulcers (DFU)-it plays a main role in the disease progression and chronicity of the lesion, the development of antibiotic resistance, and makes wound healing difficult to treat. The main problem is the difficulty in distinguishing between infection and colonization in DFU. The bacteria present in DFU are organized into functionally equivalent pathogroups that allow for close interactions between the bacteria within the biofilm. Consequently, some bacterial species that alone would be considered non-pathogenic, or incapable of maintaining a chronic infection, could co-aggregate symbiotically in a pathogenic biofilm and act synergistically to cause a chronic infection. In this review, we discuss current knowledge on biofilm formation, its presence in DFU, how the diabetic environment affects biofilm formation and its regulation, and the clinical implications.

Frequency and Antimicrobial Susceptibility Patterns of Diabetic Foot Infection of Patients from Bandar Abbas District, Southern Iran

Diabetic foot infection is among the most common complications of diabetes mellitus which significantly causes hospitalization and is the most prevalent etiology of nontraumatic amputation worldwide. The current study aimed at assessing the frequency and antimicrobial susceptibility patterns of diabetic foot infection of patients from the Bandar Abbas area, in the south of Iran. In this study, a total of 83 diabetic patients with diabetic infected foot wounds referring to Shahid Mohammadi Hospital, Bandar Abbas, from 2017 to 2018 were assessed. Samples were obtained from wound sites and evaluated by aerobic culture and also an antibiogram test for antibiotic susceptibility. Factors including age, sex, type of diabetes, the medication used for diabetes, previous history of diabetic foot infection, duration of wound incidence, fever, and laboratory indices were recorded for each subject. The most prevalent detected bacteria were Escherichia coli (20.5%), Enterococcus sp. (16.9%), Klebsiella sp. (12%), Staphylococcus aureus (8.4%), Enterobacter sp. (7.2%), and Acinetobacter sp. (6%). The results of antibiogram tests revealed the most and the least antibiotic sensitivity for E. coli sp. as meropenem and ciprofloxacin, for Enterococcus sp. as gentamicin and ciprofloxacin, for Klebsiella sp. as amikacin and cotrimoxazole, and for Enterobacter sp. as cotrimoxazole and both amikacin and ciprofloxacin. Staphylococcus aureus was sensitive to vancomycin and doxycycline, and Acinetobacter sp. was 100% resistant to all antibiotics except amikacin and gentamycin. A significant statistical association was found between the C-reactive protein and the patients' diabetic foot infection organisms (P=0.019). Findings of the study revealed E. coli sp. as the most common bacteria which are infecting the foot lesions in the studied population. The highest antibiotic susceptibility was seen for vancomycin, linezolid, and carbapenem.

Admission Time Deep Swab Specimens Compared With Surgical Bone Sampling in Hospitalized Individuals With Diabetic Foot Osteomyelitis and Soft Tissue Infection

Whether deep swab cultures taken at admission reliably identify pathogens compared to surgical bone specimens in hospitalized individuals with diabetic foot osteomyelitis and soft tissue infection is unclear. Comparison of microbiological isolates between a deep wound swab (DWS) taken at the time of admission through the actively infected, discharging ulcer probing to the bone and the subsequent surgical bone sample (SBS) taken during surgical debridement was made. A total of 63 subjects (age 60.8 ± 13.5 years, 75% male, 80% Type 2 diabetes, HbA1C 8.9%±2.2%) were included. The proportion of Gram-positive (DWS 49% v SBS 52%) and Gram-negative (DWS 60% v SBS 60%) isolates was similar between the techniques. However, the overall concordance of isolates between the two techniques was only fair (κ=0.302). The best concordance was observed for Staphylococcus aureus (κ=0.571) and MRSA (κ=0.644). There was a correlation between number of isolates in SBS with prior antibiotic therapy of any duration (r= -0.358, p=0.005) and with the duration of ulceration (r=0.296, p=0.045); no clinical correlations were found for DWS. Prior antibiotic therapy (p=0.03) and duration of ulceration <8 weeks (p=0.025) were predictive of negative growth on SBS. In conclusion, we found only a fair concordance between deep wound swabs acquired at admission and surgical bone specimens in those presenting with a severe diabetic foot infection and features of osteomyelitis. Ensuring early surgical debridement of all infected tissue and obtaining bone specimens should be considered a clinical priority, which may also reduce the likelihood of negative growth on SBS.

Utility of Methicillin-Resistant Staphylococcus aureus Nares Screening for Patients with a Diabetic Foot Infection

Treatment of suspected methicillin-resistant Staphylococcus aureus (MRSA) is a cornerstone of severe diabetic foot infections; however, antibiotics can be associated with toxicity. The objective of this study was to determine the negative predictive value (NPV) of MRSA nares screening in the determination of subsequent MRSA in patients with a diabetic foot infection. This was a retrospective cohort study across Veterans Affairs (VA) medical centers from 1 January 2007 to 1 January 2018. Data from patients with an International Classification of Diseases (ICD) code for a diabetic foot infection with MRSA nares screening, and subsequent cultures were evaluated for the presence of MRSA. NPVs were calculated for the entire cohort, as well as for a subgroup representing deep cultures. Additionally, the distribution of all pathogens isolated from diabetic foot infections was determined. A total of 8,163 episodes were included in the analysis for NPV. The NPV of MRSA nares screening for MRSA diabetic foot infection was 89.6%. For the deep cultures, the NPV was 89.2%. The NPV for cultures originating from the foot was 89.7%, and the NPV for those originating from the toe was 89.4%. There were 17,822 pathogens isolated from the diabetic foot cultures. MRSA was isolated in 7.5% of cultures, and methicillin-susceptible S. aureus was isolated in 24.8%. Enterococcus was identified in 14.7% of cultures, Proteus in 7.3%, and Pseudomonas in 6.8% of cultures. Given the high NPVs, the use of MRSA nares screening may be appropriate as a stewardship tool for deescalation and avoidance of empirical anti-MRSA therapy in patients who are not nasal carries of MRSA.

Prevalence and interrelationships of foot ulcer, risk-factors and antibiotic resistance in foot ulcers in diabetic populations: A systematic review and meta-analysis

BACKGROUND

Diabetic foot ulceration (DFU) is the prime health concern globally. It accounts for the major burden related to disease mortality and morbidity and economic cost. The timely and early recognition of the DFU can help present its occurrence and improve clinical outcomes.

AIM

To evaluate interrelationships between foot ulcers, risk factors, and antibiotic resistance among diabetic patients having ulcers in their foot.

METHODS

The databases such as PubMed, ERIC, Medline, and Google Scholar were extensively used for the extraction of studies. The selected studies were published within the time-period of 2014-2018. Ten studies were selected, which were found to be completely relevant to the current study.

RESULTS

The prevalence of diabetic foot ulcers among the population was evaluated, and the associated risk factors with its prevalence. Moreover, few studies also reported on the bacteria that are found to be most prevailing among diabetic patients. A narrative discussion was drawn through this analysis, which was used to highlight the specific area of research through selected studies, extraction of the significant information that matched with the topic of research, and analysis of problem through the findings of the selected articles. The results helped in assessing significant knowledge regarding the risk factors of diabetic foot ulcers and the role of antimicrobial resistant in its treatment.

CONCLUSION

The gram-negative bacteria were found to be the most common reason for diabetic foot ulcers. The study only included 10 studies that are not sufficient to produce generalized results, and no information was reported on the tests required to analyze antimicrobial susceptibility that can guide clinicians to propose better and sound treatment plans. It is evident that most study results depicted that the most common risk factors were found to be hypertension and neuropathy.

Synergistic Antibacterial Activity and Wound Healing Properties of Selenium-Chitosan-Mupirocin Nanohybrid System: An in Vivo Study on Rat Diabetic Staphylococcus aureus Wound Infection Model

The current study aimed to formulate Selenium-Chitosan-Mupirocin (M-SeNPs-CCH) complex. The nanohybrid system was prepared using chitosan-cetyltrimethylammonium bromide (CTAB)-based hydrogel (CCH) that entrapped mupirocin (M) and selenium nanoparticles (SeNPs). The in vitro studies were performed by evaluation of the antibacterial activity and toxicity on L929 mouse fibroblast cell line. The in vivo study was conducted on rat diabetic wound infection model that was infected by mupirocin-methicillin-resistant Staphylococcus aureus (MMRSA). The wounds were treated by M-SeNPs-CCH nanohybrid system with concentrations of M; 20 mg/ml, CCH; 2 mg/ml and SeNPs; 512 μg/ml in two times/day for 21 days. The therapeutic effect of this nanohybrid system was evaluated by monitoring wound contraction and histopathological changes. Evaluation of the average wound healing time showed a significant difference between the treatment and control groups (P≤0.05). The histopathological study indicated that the amount of wound healing was considerable in M-SeNPs-CCH nanohybrid system groups compared to the control and M groups. The M-SeNPs-CCH nanohybrid system formulated in this study was able to reduce 3-fold MIC of mupirocin with synergistic antibacterial activity as well as to play a significant role in wound contraction, angiogenesis, fibroblastosis, collagenesis, proliferation of hair follicle, and epidermis growth compared to the control group (P ≤ 0.05). This research suggests that this nanohybrid system might be a development for the treatment of diabetic wound infection at mild stage.

Differences in foot skin microbiomes between patients with type 2 diabetes and healthy individuals

Impaired immunity and changes in the microenvironment in patients with diabetes might influence the composition of the cutaneous microbiome. However, data on the cutaneous microbiome of these patients are scarce. This study compared the fungal and bacterial components of the skin microbiome between patients with type 2 diabetes mellitus (DM) and healthy individuals. We obtained skin swab samples from the plantar forefoot of 17 patients with DM and 18 healthy individuals to conduct a cross-sectional study. The samples were profiled with culture-independent sequencing of the V3 to V4 regions of the bacterial 16S rRNA gene and the fungal ITS2 region, followed by direct DNA extraction and molecular polymerase chain reaction (PCR). We observed a differential cutaneous microbiome, especially for fungi, in patients with type 2 diabetes compared to that in healthy controls. Trichophyton rubrum was more abundant in DM samples. The Shannon diversity index for fungi was lower in the DM patients. Principal coordinate analysis plots and permutational multivariate analysis of variance (PERMANOVA) tests based on Bray-Curtis distances between samples supported the association of the fungal microbiome with DM at the species level. The results suggest that clinicians should pay attention to both fungi and bacteria and provide appropriate prevention and therapeutic strategies for diabetic cutaneous complications including diabetic foot ulcers. These data also contribute to future research associated with diabetes and cutaneous microbiomes.

Epidermal growth factor vs platelet-rich plasma: Activity against chronic wound microbiota

The objective was to evaluate Staphylococcus aureus and Pseudomonas aeruginosa colonisation of wounds treated with recombinant epidermal growth factor (EGF) and platelet-rich plasma (PRP); to analyse the susceptibility profiles of S. aureus and P. aeruginosa isolates from wounds treated with EGF and PRP; and to describe the presence of infection in EGF-treated and PRP-treated wounds. Experimental study was performed using clinical specimens collected with swabs. Patients were treated with PRP and EGF in the outpatient clinic of a university hospital. Forty-three isolates were obtained from 31 patients, 41.9% (13/31) of whom had been treated with EGF and 58.0% (18/31) with PRP. Ten of the 43 isolates were identified as S. aureus, 60.0% (6/10) of which were isolated from PRP-treated wounds. Among the 33 P. aeruginosa isolates, 66.6% (22/33) were isolated from PRP-treated wounds. Regarding antimicrobial susceptibility, only one strain isolated from an EGF-treated wound was identified as methicillin-resistant S. aureus (MRSA). Among the P. aeruginosa isolates, one obtained from a patient treated with EGF was multidrug-resistant. Patients treated with EGF had no infections during the follow-up period, and there was a significant difference between the 1st and 12th week in wound infection improvement in patients treated with PRP (P = .0078).

Molecular Characteristics of Methicillin-Resistant Staphylococcus aureus (MRSA) Isolated from Diabetic Foot Infection

Background & Objective:

Diabetic foot ulcer (DFU), is one of the most frequent causes for hospitalizations in patients with diabetes. A major problem in the treatment of DFU is the increased-incidence of methicillin-resistant Staphylococcus aureus (MRSA). The aim of this study was to determine the SCCmec types of MRSA isolates and their epidemiology among patients with diabetes.

Methods:

This study was carried out on 145 diabetic patients with DFUs. The antibiotic susceptibility tests (ASTs) were performed using the disk diffusion method and E-test technique. SCCmec typing was done by multiplex PCR. Moreover, the presence of virulence toxin genes, including pvl and lukED was detected by PCR assay.

Results:

In 145 samples from which S. aureus was predominantly isolated, 19.48% were MRSA. Analysis of MRSA isolates revealed that the most prevalent SCCmec type was type IV (46.7%) followed by type III (30.0%) and type V (20.0%). One strain (3.3%) was untypeable. The prevalence of pvl and lukED was 56.7% and 100%, respectively.

Conclusion:

The high prevalence of MRSA in DFUs represents the high levels of antibiotic usage among patients with diabetes. In this study, resistance to other important clinical antibiotics was detected among MRSA isolates. The high proportion of SCCmec type IV and V strains, even in former hospitalized patients, indicates the entrance of these clones to the clinical setting.

The what, when and how in performing and interpreting microbiological diagnostic tests in skin and soft tissue infections

PURPOSE OF REVIEW

To summarize and classify the most recent and relevant microbiological studies for each type of skin and soft tissue infection (SSTI).

RECENT FINDINGS

Following Infectious Diseases Society of America and Food and Drug Administration classifications of SSTIs, we differentiate between two large groups, the superficial or uncomplicated infections and the complicated infections with deep involvement. It is not usually necessary to obtain microbiological samples in uncomplicated infections, except in cases of recurrences or for epidemiological control purposes. In the case of complicated infections, the samples are of two different types: those obtained from the affected area (surgical samples, punctures of abscesses or swabs) and systemic samples (i.e. blood cultures). The clinical condition also determines the type of samples to be obtained. In cases of systemic involvement, blood cultures are mandatory. For immunocompromised patients, who may present atypical infections, detection of antigens, serologies or molecular biology techniques may be helpful. The rapid diagnosis is currently the goal to be pursued by implementing techniques such as matrix assisted laser desorption ionization-time of flight, commercial real-time PCR or the promising metagenomics.

SUMMARY

Microbiological diagnosis is one of the cornerstones of the management of SSTIs. Prompt obtaining and processing of the necessary samples, depending on the clinical situation of the patient, is of relevance in the decision-making process. Rapid and fluid reporting of the results (identification, mechanisms of resistance and antibiogram) will improve the management of these patients.

Surgical Diabetic Foot Debridement: Improving Training and Practice Utilizing the Traffic Light Principle

Comprehensive management of a severe diabetic foot infection focus on clear treatment pathways. Including rapid, radical debridement of all infection in addition to intravenous antibiotics and supportive measures. However, inexperienced surgeons can often underestimate the extent of infection, risking inadequate debridement, repeated theatre episodes, higher hospital morbidity, and hospital length of stay (LOS). This study aims to assess protocolized diabetic-foot-debridement: Red-Amber-Green (RAG) model as part of a value-based driven intervention. The model highlights necrotic/infected tissue (red-zone, nonviable), followed by areas of moderate damage (amber-zone), healthy tissue (green-zone, viable). Sequential training of orthopedic surgeons supporting our emergency service was undertaken prior to introduction. We compared outcomes before/after RAG introduction (pre-RAG, n = 48; post- RAG, n = 35). Outcomes measured included: impact on number of debridement/individual admission, percentage of individuals requiring multiple debridement, and length-of-hospital-stay as a function-of-cost. All-patients fulfilled grade 2/3, stage-B, of the Texas-Wound-Classification. Those with evidence of ischemia were excluded. The pre-RAG-group were younger (53.8 ± 11.0 years vs 60.3 ± 9.2 years, P = .01); otherwise the 2-groups were matched: HbA1c, white blood cell count, and C-reactive protein. The post-RAG-group underwent significantly lower numbers of debridement's (1.1 ± 0.3 vs 1.5 ± 0.6/individual admission, P = .003); equired fewer visits to theatre (8.6% vs 38%, P = .003), their LOS was reduced (median LOS pre-RAG 36.0 vs post-RAG 21.5 days, P = .02). RAG facilitates infection clearance, fewer theatre-episodes, and shorter LOS. This protocolized-management-tools in acute severely infected diabetic foot infection offers benefits to patients and health-care-gain.

Diabetic Foot Infection: Causative Pathogens and Empiric Antibiotherapy Considerations—The Experience of a Tertiary Center

Most moderate-to-severe diabetic foot infections (DFIs) require hospitalization with urgent surgical approach and administration of empiric antibiotherapy. To ensure optimal antibiotic coverage, regular microbiological background updates are imperative. The purpose is to characterize the microbiological profile and the antibiotic sensitivity pattern of the DFI causative pathogens isolated within a specialized DFI unit of a tertiary hospital, in order to establish evidence-based policies regarding empirical antibiotic use. A cross-sectional study was conducted. Microbiological cultures and corresponding antibiotic sensitivity tests collected from moderate-to-severe DFIs as a first approach to the hospitalized patient were retrieved and analyzed during a 12-month period. Two groups were analyzed: inpatients that had been previously followed at the diabetic foot clinic of the hospital and inpatients without a previous contact with the hospital services. A total of 125 isolates obtained from 87 patients were deemed for analysis. Globally, a predominance of Gram-positive bacteria was observed (60%). Staphylococcus aureus was the most common pathogen. The global ratio of methicillin-sensitive S aureus to methicillin-resistant S aureus (MRSA) was 1.3:1, with similar findings in both groups. According to the antibiotic sensitivity test results, and within the recommended empiric antibiotic regimens for DFI, piperacillin/tazobactam seems to be the most suitable option. Gram-positive bacteria prevail as the main isolates in DFIs. Screening for MRSA-specific risk factors is mandatory. When going for a first empiric therapy, piperacillin/tazobactam is recommended in this institution, and an anti-MRSA agent should be added early, if necessary. We encourage continuous monitoring for the bacterial prevalence in Portuguese diabetic foot centers as it is paramount for the decision making regarding DFI protocols.

Bacterial isolation and antibiotic susceptibility from diabetic foot ulcers in Kenya using microbiological tests and comparison with RT-PCR in detection of S. aureus and MRSA

OBJECTIVES

Diabetic foot ulcers (DFUs) often lead to hospital admissions, amputations and deaths; however, there is no up-to-date information on microbial isolates from DFUs and no mention of utilization of molecular techniques in Sub-Saharan Africa. We conducted a cross-sectional study among 83 adult patients at a tertiary hospital in Kenya over 12 months. The study aimed to isolate, identify bacteria, their antibiotic susceptibility patterns in active DFUs, and to compare standard microbiological methods versus a real-time PCR commercial kit in the detection of Staphylococcus aureus DNA and methicillin-resistant S. aureus (MRSA) DNA.

RESULTS

Eighty swabs (94%) were culture-positive; 29% were Gram-positive and 65% were Gram-negative. The main organisms isolated were S. aureus (16%), Escherichia coli (15%), Proteus mirabilis (11%), Klebsiella pneumoniae (7%) and Pseudomonas aeruginosa (7%). The bacterial isolates showed resistance to commonly used antibiotics such as ampicillin, amoxicillin, cefepime, ceftazidime, cefuroxime, clindamycin, erythromycin, piperacillin-tazobactam, tetracycline and trimethoprim-sulphamethoxazole (TMPSMX). Thirty-one percent of the S. aureus isolated and 40% of the Gram-negatives were multi-drug resistant organisms (MDROs). There was a high prevalence of nosocomial bacteria. MRSA were not identified using culture methods but were identified using PCR. PCR was more sensitive but less specific than culture-based methods to identify S. aureus.