Diabetic foot infections. Bacteriology and activity of 10 oral antimicrobial agents against bacteria isolated from consecutive cases

In situ photo-crosslinking silk fibroin based hydrogel accelerates diabetic wound healing through antibacterial and antioxidant

Bacterial infection and excessive reactive oxygen species (ROS) in diabetic wounds lead to a prolonged inflammatory phase, and injuries are highly susceptible to developing into chronic wounds. Improving the poor microenvironment is vital to achieving effective diabetic wound healing. In this work, methacrylated silk fibroin (SFMA) was combined with ε-polylysine (EPL) and manganese dioxide nanoparticles (BMNPs) to form an SF@(EPL-BM) hydrogel with in situ forming, antibacterial and antioxidant properties. EPL imparted high antibacterial activity (>96 %) to the hydrogel. BMNPs and EPL showed good scavenging activity against a variety of free radicals. SF@(EPL-BM) hydrogel had low cytotoxicity and could alleviate H₂O₂-induced oxidative stress in L929 cells. In diabetic wounds infected with Staphylococcus aureus (S. aureus), the SF@(EPL-BM) hydrogel exhibited better antibacterial properties and reduced wound ROS levels more significantly than that of the control in vivo. In this process, the pro-inflammatory factor TNF-α was down-regulated, and the vascularization marker CD31 was up-regulated. H&E and Masson staining showed a rapid transition from the inflammatory to the proliferative phase of the wounds, with significant new tissue and collagen deposition. These results confirm that this multifunctional hydrogel dressing holds well potential for chronic wound healing.

Diabetic foot infections: A microbiologic review

Diabetes mellitus continues to be an increasingly common comorbidity. Diabetic foot infections are one of the most common causes of hospitalization in this population, and account for a significant portion of increased hospitalization and healthcare expenditure. Complications, such as osteomyelitis, can necessitate the use of multiple, prolonged antibiotic courses. These courses often consist of broad-spectrum, empiric therapy determined by organisms considered to be commonly associated with these types of infections. Extended periods of broad-spectrum antibiotic regimens can contribute to antibiotic resistance and ultimately limit future treatment options. Furthermore, patient specific risk factors can impact the microbiologic diversity found in these infections. As a result, it is difficult to determine if a single empiric regimen is appropriate for all instances of diabetic foot infections.

OBJECTIVES AND METHODS

This review analyzes global literature relating to the culture methods, incidence, risk factors, resistance patterns, and geographic distribution of the microorganisms isolated from diabetic foot infections using the PRISMA statement for systematic review and meta-analysis reporting.

RESULTS

Staphylococcus aureus remains a significant pathogen, with a growing incidence of Pseudomonas aeruginosa and MDR gram-negative bacilli.

CONCLUSIONS

Though some individualized risk factors can be useful, local epidemiology and resistance patterns remain essential for antibiotic treatment considerations.

Clinical and bacteriological profile of diabetic foot infections in a tertiary care

BACKGROUND

Diabetic foot infection is a worldwide health problem is commonly encountered in daily practice. This study was conducted to identify the microbiological profile and antibiotic sensitivity patterns of causative agents identified from diabetic foot infections (DFIs). In addition, the assessment included probable risk factors contributing to infection of ulcers that harbour multidrug-resistant organisms (MDROs) and their outcomes.

METHODS

We carried out a prospective analysis based on the DFI samples collected from 2016 till 2018. Specimens were cultured with optimal techniques in addition to antibiotic susceptibility based on recommendations from The Clinical and Laboratory Standards Institute (CLSI). A total of 1040 pathogens were isolated with an average of 1.9 pathogens per lesion in 550 patients who were identified with having DFIs during this interval.

RESULTS

A higher percentage of Gram-negative pathogens (54%) were identified as compared with Gram-positive pathogens (33%) or anaerobes (12%). A total of 85% of the patients were found to have polymicrobial infections. Pseudomonas aeruginosa (19%), Staphylococcus aureus (11%) and Bacteroides species (8%) appeared to be the predominant organisms isolated. In the management of Gram-positive bacteria, the most efficacious treatment was seen with the use of Vancomycin, while Imipenem and Amikacin proved to be effective in the treatment of Gram-negative bacteria.

CONCLUSION

DFI's are common among Malaysians with diabetes, with a majority of cases displaying polymicrobial aetiology with multi-drug resistant isolates. The data obtained from this study will be valuable in aiding future empirical treatment guidelines in the treatment of DFIs. This study investigated the microbiology of DFIs and their resistance to antibiotics in patients with DFIs that were managed at a Tertiary Care Centre in Malaysia.

Susceptibility of monomicrobial or polymicrobial biofilms derived from infected diabetic foot ulcers to topical or systemic antibiotics in vitro

Diabetic foot ulcers can become chronic and non-healing despite systemic antibiotic treatment. The penetration of systematically-administered antibiotics to the site of infection is uncertain, as is the effectiveness of such levels against polymicrobial biofilms. We have developed an in vitro model to study the effectiveness of different treatments for infected diabetic foot ulcers in a wound-like environment and compared the activity of systemic levels of antibiotics with that for topically applied antibiotics released from calcium sulfate beads. This is the first study that has harvested bacteria from diabetic foot infections and recreated similar polymicrobial biofilms to those present in vivo for individual subjects. After treatment with levels of gentamicin attained in serum after systemic administration (higher than corresponding tissues concentrations) we measured a 0-2 log reduction in bacterial viability of P. aeruginosa, S. aureus or a polymicrobial biofilm. Conversely, addition of gentamicin loaded calcium sulfate beads resulted in 5-9 log reductions in P. aeruginosa, S aureus and polymicrobial biofilms derived from three subjects. We conclude that systemically administered antibiotics are likely to be inadequate for successfully treating these infections, especially given the vastly increased concentrations required to inhibit cells in a biofilm, and that topical antibiotics provide a more effective alternative.

The prevalence of methicillin-resistant Staphylococcus aureus among diabetic patients: a meta-analysis

AIMS

Diabetic patients have multiple risk factors for colonisation with methicillin-resistant Staphylococcus aureus (MRSA), a nosocomial pathogen associated with significant morbidity and mortality. This meta-analysis was conducted to estimate the prevalence of MRSA among diabetic patients.

METHODS

The MEDLINE, Embase, BIOSIS, and Web of Science databases were searched for studies published up to May 2018 that reported primary data on the prevalence of MRSA in 10 or more diabetic patients. Two authors independently assessed study eligibility and extracted the data. The main outcomes were the pooled prevalence rates of MRSA colonisation and infection among diabetic populations.

RESULTS

Eligible data sets were divided into three groups containing data about the prevalence of MRSA colonisation or in diabetic foot or other infections. From 23 data sets, the prevalence of MRSA colonisation among 11577 diabetics was 9.20% (95% CI, 6.26-12.63%). Comparison of data from 14 studies that examined diabetic and non-diabetic patients found that diabetics had a 4.75% greater colonisation rate (P < 0.0001). From 41 data sets, the prevalence of MRSA in 10994 diabetic foot infection patients was 16.78% (95% CI, 13.21-20.68%). Among 2147 non-foot skin and soft-tissue infections, the MRSA prevalence rate was 18.03% (95% CI, 6.64-33.41).

CONCLUSIONS

The prevalence of MRSA colonisation among diabetic patients is often higher than among non-diabetics; this may make targeted screening attractive. In the UK, many diabetic patients may already be covered by the current screening policies. The prevalence and impact of MRSA among diabetic healthcare workers requires further research. The high prevalence of MRSA among diabetic foot infections may have implications for antimicrobial resistance, and should encourage strategies aimed at infection prevention or alternative therapies.

Should Treatment of Diabetic Foot Osteomyelitis Be Based on Bone Biopsies?

RECOMMENDATION

Yes. Bone biopsies play both a crucial diagnostic and interventional role in the management of diabetic foot infection. Although bone biopsies are not required in every case of diabetic foot infection, their most important role is in guiding accurate antibiotic treatment, as they provide more accurate microbiological information than superficial soft tissue samples in patients with diabetic foot osteomyelitis.

LEVEL OF EVIDENCE

Moderate.

DELEGATE VOTE

Agree: 100%, Disagree: 0%, Abstain: 0% (Unanimous, Strongest Consensus).

The Significant Association between Polymicrobial Diabetic Foot Infection and Its Severity and Outcomes

Background

Foot infection is a major complication of diabetes mellitus (DM) and its agents are usually polymicrobial. This study aims to describe the agent and determine the association between polymicrobial infections and the severity of diabetic foot infections (DFI) and their outcomes.

Methods

This retrospective cohort study was conducted during one year and it involved 104 patients. Their records were reviewed and assessed. The causative agents and its sensitivity pattern were noted. The results were presented as descriptive statistic and analysed.

Results

A total of 133 microorganisms were isolated with 1.28 microorganisms per lesion. The microorganism isolated were 62% (n = 83) GN (Gram-negative) and 38% (n = 50) GP (Gram-positive). GN microorganisms include Pseudomonas spp (28%), Proteus spp (11%), Klebsiella spp (8%) and E. coli (4%). Staphylococcus aureus (54%) was predominant among GP, followed by Group B Streptococci (26%) and Enterococcus spp (6%). Thirty patients (28.8%) had polymicrobial infections. The association between the quantity of microorganisms and severity of DFI was significant. Among severe DFI cases, 77.8% with polymicrobial microorganisms underwent amputation compared to 33.3% with monomicrobial infection.

Conclusion

GN microorganisms were predominantly isolated from DFIs and remained sensitive to widely used agents. Polymicrobial infections were associated with DFI severity.

Classification, microbiology and treatment of diabetic foot infections

Diabetic foot ulcers (DFUs) are a common complication of type-1 and type-2 diabetes. About 10-15% of patients with diabetes develop foot ulcers. A validated foot ulcer classification system that will support the development of treatment strategis is necessary for clinicians managing DFUs. More than 10 classification systems have been described by researchers. Another important aspect of the management of DFUs is the proper identification of causative pathogens that trigger infections. While conventional diagnostic methods, such as swabs, cultures and biopsies are more widely used, novel molecular techniques have been exploring bacterial identification and quantification. Knowledge of the microbial aetiologies in diabetic foot infections, and understanding of antibiotic resistance, is critical for the effective management and treatment of these infected wounds. Initial antibiotic regimens are usually selected empirically. A set of common principles may help avoid selecting either an unnecessarily broad or inappropriately narrow antibiotic treatment regimen. In this review we provide a comprehensive summary and description of classification systems of diabetic foot infections, and a comprehensive discussion of microbiology.

Epidemiology of diabetic foot infections in a reference tertiary hospital in India

Introduction

The present study attempts to examine the microbial profile and antibiotic susceptibility of diabetic foot infections in the intensive care unit of a tertiary referral centre for diabetic foot. As part of the study, we also attempted to find the prevalence of blaNDM-like gene among carbapenem-resistant gram negative infections.

Methodology

A prospective study of 261 patients with diabetic foot infections was performed during the period between January 2014 and June 2014.

Results

A total of 289 isolates were obtained from 178 tissue samples from 261 patients, 156 (59.7%) males and 105 (40.2%) females, with a mean age of 58 years (−15 years), having diabetic foot infection. No growth was seen in thirty eight (17.6%) tissue samples. Out of the total samples, 44.3% were monomicrobial and 55.7% were polymicrobial. Gram negative pathogens were predominant (58.5%). Seven of the total isolates were fungal; 0.7% showed pure fungal growth and 1.7% were mixed, grown along with some bacteria. The most frequently isolated bacteria were Staphylococcus aureus (26.9%), followed by Pseudomonas aeruginosa (20.9%). Of the 58.5% gram negative pathogens, 16.5% were Enterobacteriaceae resistant to carbapenems. Among these isolates, 4 (25%) were positive for blaNDM-like gene. Among the rest, 18.6% were carbapenem-resistant Pseudomonas, among which 4 (36.3%) were blaNDM. Among the Staphylococci, 23.7% were methicillin-resistant Staphylococcus aureus.

Conclusions

Our results support the recent view that gram negative organisms, depending on the geographical location, may be predominant in DFIs. There is an increase in multidrug-resistant pathogens, especially carbapenem resistance and this is creeping rapidly. We need to be more judicious while using empiric antibiotics.

Empirical Antibiotic Treatment in Diabetic Foot Infection: A Study Focusing on the Culture and Antibiotic Sensitivity in a Population From Southern China

Diabetic foot and subsequent diabetic ulcer infections are the most devastating complication of diabetes. This study was conducted to explore the bacterial spectrum, sensitivity of microbials, and analysis of the empirical antibiotic regimens in our health center. The study included patients with diabetic foot ulcer infection (DFI) seen from 2009 to 2014. The patients included had all information covering the physical examination, laboratory tests, and image examinations. We sent appropriately obtained specimens for culture prior to starting empirical antibiotic therapy in all participants. A total of 312 patients were included: 52, 112, 95 and 53 patients within uninfected, mild, moderate, and severe infection groups. The total percentages of Gram-positive cocci (GPCs) and Gram-negative rods (GNRs) were 54% and 48.8% ( P = 0.63). The most common GPC was Staphylococcus aureus (22.4%) and GNR was Pseudomonas aeruginosa (11.9%). Methicillin-resistant Staphylococcus aureus was isolated from 21 patients (6.7%). Even in the mild infection group, there was no significant difference between GPC and GNR infection, irrespective of recent antibiotic use ( P = 0.053). The most frequently used empirical antibiotics in our center were second-/third-generation cephalosporin ± clindamycin, both in the mild and moderate/severe infection groups. In our center, the amoxicillin/clavulanate or ampicillin/sulbactam (β-L-ase 1) and second-/third-generation cephalosporins were highly resistant to the common GNR (30%-60%). The ticarcillin/clavulanate, piperacillin/tazuobactam (β-L-ase 2), fluoroquinolone, and group 2 carbapenem had good sensitivity. This study presents a comprehensive microbiological survey of diabetic foot ulcers in inpatients and provides reliable evidence of the local microbial epidemiology and sensitivity of antibiotics, which may help us improve clinical outcomes in DFI patients.

Glycosaminoglycan-based hydrogels capture inflammatory chemokines and rescue defective wound healing in mice

Excessive production of inflammatory chemokines can cause chronic inflammation and thus impair cutaneous wound healing. Capturing chemokine signals using wound dressing materials may offer powerful new treatment modalities for chronic wounds. Here, a modular hydrogel based on end-functionalized star-shaped polyethylene glycol (starPEG) and derivatives of the glycosaminoglycan (GAG) heparin was customized for maximal chemokine sequestration. The material is shown to effectively scavenge the inflammatory chemokines MCP-1 (monocyte chemoattractant protein-1), IL-8 (interleukin-8), and MIP-1α (macrophage inflammatory protein-1α) and MIP-1β (macrophage inflammatory protein-1β) in wound fluids from patients suffering from chronic venous leg ulcers and to reduce the migratory activity of human monocytes and polymorphonuclear neutrophils. In an in vivo model of delayed wound healing (db/db mice), starPEG-GAG hydrogels outperformed the standard-of-care product Promogran with respect to reduction of inflammation, as well as increased granulation tissue formation, vascularization, and wound closure.

Effectiveness of a polyhexanide irrigation solution on methicillin-resistant Staphylococcus aureus biofilms in a porcine wound model

Irrigation and removal of necrotic debris can be beneficial for proper healing. It is becoming increasingly evident that wounds colonized with biofilm forming bacteria, such as Staphylococcus aureus (SA), can be more difficult to eradicate. Here we report our findings of the effects of an irrigation solution containing propyl-betaine and polyhexanide (PHMB) on methicillin-resistant Staphylococcus aureus (MRSA) biofilms in a porcine wound model. Thirty-nine deep partial thickness wounds were created with six wounds assigned to one of six treatment groups: (i) PHMB, (ii) Ringer's solution, (iii) hypochlorous acid/sodium hypochlorite, (iv) sterile water, (v) octenidine dihydrochloride, and (vi) octenilin. Wounds were inoculated with MRSA and covered with a polyurethane dressing for 24 hours to allow biofilm formation. The dressings were then removed and the wounds were irrigated twice daily for 3 days with the appropriate solution. MRSA from four wounds were recovered from each treatment group at 3 days and 6 days hours after initial treatment. Irrigation of wounds with the PHMB solution resulted in 97·85% and 99·64% reductions of MRSA at the respective 3 days and 6 days assessment times when compared to the untreated group. Both of these reductions were statistically significant compared to all other treatment groups (P values <0·05).

The microbiology of diabetic foot infections in patients recently treated with antibiotic therapy: A prospective study from India

AIM

Clinicians often treat clinically infected diabetic foot ulcers without information from cultures of the wound. The results of wound cultures may also be affected by previous antibiotic therapy. Thus, we aimed to study the microbial isolates, and antimicrobial sensitivity of previously treated patients with a clinically infected DFU.

RESEARCH DESIGN AND METHODS

293 consecutive patients with clinically infected DFU on prior antimicrobial treatment within the immediate past few days for a duration greater than one week were evaluated for microbial etiology, antibiotic sensitivity and final outcomes. Appropriate tissue samples i.e. purulent drainage, soft-tissue and/ or bone were obtained for aerobic/anaerobic cultures and antimicrobial sensitivities. 71 patients with missing prior antibiotic data were excluded.

RESULTS

313 tissue samples obtained from 222 patients isolated 317 causative organisms. Most of the culture results from tissue specimens were mono-microbial (93.2%) compared to 37% in our previous cohort of 60 patients. Pseudomonas aeruginosa was the most common organism isolated on culture of bone (26.9%) or soft tissue (23.2%) specimen, respectively. Only 23% and 64% of P. aeruginosa isolates and 5.6% and 44% of Acinetobacter sp. were sensitive to quinolones and cephalosporins, respectively.

CONCLUSIONS

Clinically infected DFU recently treated with antibiotics have predominant monomicrobial and multi drug-resistant infection. Quinolones as an empirical antibiotic choice may not be appropriate in this setting.

Aerobic bacterial profile and antibiotic resistance in patients with diabetic foot infections

INTRODUCTION

This study aimed to determine the frequencies of bacterial isolates cultured from diabetic foot infections and assess their resistance and susceptibility to commonly used antibiotics.

METHODS

This prospective study included 41 patients with diabetic foot lesions. Bacteria were isolated from foot lesions, and their antibiotic susceptibility pattern was determined using the Kirby-Bauer disk diffusion method and/or broth method [minimum inhibitory concentration (MIC)].

RESULTS

The most common location of ulceration was the toe (54%), followed by the plantar surface (27%) and dorsal portion (19%). A total of 89 bacterial isolates were obtained from 30 patients. The infections were predominantly due to Gram-positive bacteria and polymicrobial bacteremia. The most commonly isolated Gram-positive bacteria were Staphylococcus aureus, followed by Staphylococcus saprophyticus, Staphylococcus epidermidis, Streptococcus agalactiae, and Streptococcus pneumoniae. The most commonly isolated Gram-negative bacteria were Proteus spp. and Enterobacterspp., followed by Escherichia coli, Pseudomonasspp., and Citrobacterspp. Nine cases of methicillin-resistant Staphylococcus aureus (MRSA) had cefoxitin resistance, and among these MRSA isolates, 3 were resistant to vancomycin with the MIC technique. The antibiotic imipenem was the most effective against both Gram-positive and Gram-negative bacteria, and gentamicin was effective against Gram-negative bacteria.

CONCLUSIONS

The present study confirmed the high prevalence of multidrug-resistant pathogens in diabetic foot ulcers. It is necessary to evaluate the different microorganisms infecting the wound and to know the antibiotic susceptibility patterns of the isolates from the infected wound. This knowledge is crucial for planning treatment with the appropriate antibiotics, reducing resistance patterns, and minimizing healthcare costs.

Do Diabetic Foot Infections With Methicillin-Resistant Staphylococcus aureus Differ From Those With Other Pathogens?

There is controversy as to whether or not diabetic foot infections (DFIs) caused by methicillin-resistant Staphylococcus aureus (MRSA) are associated with worse outcomes than DFIs caused by other pathogens. To address this issue we performed a nonsystematic literature search of published articles in English language journals seeking studies reporting on the outcomes of DFIs related to their microbiology. We retrieved 48 articles published from 1999 to 2013 that described a total of 7771 cases of DFI. The overall proportion of DFIs with an isolate of S aureus was about 30%; just over one third of these (11% of all cases) were MRSA strains. Among the DFI cases caused by MRSA 1543 were episodes of soft tissue infections and 113 of osteomyelitis, while non-MRSA organisms caused 5761 soft tissue infections and 354 cases of osteomyelitis. Only 5 of the included articles attempted a comparison between DFI caused by MRSA and those caused by other pathogens, with no clear differences noted. The median total duration of antibiotic therapy for DFI caused by MRSA was 26 days, of which a median of 10 days was given intravenously. Only a few articles reported the proportion of patients with a recurrence, but they often did not differentiate between MRSA and non-MRSA cases. Four publications reported a worse functional or microbiological outcome in MRSA, compared to non-MRSA, cases, but the findings were variable and differences did not seem to be significant. Many trials failed to adjust for case-mix or to definitively demonstrate a relationship between microbiology and outcomes. Few of the articles specifically commented on whether the MRSA isolates were health care- or community-acquired strains. Notwithstanding the substantial limitations of the available literature, there does not appear to be a need for any special treatment for DFI caused by MRSA. The current guidelines for treating according to established international recommendations seem appropriate.

Active wound dressings based on bacterial nanocellulose as drug delivery system for octenidine

Although bacterial nanocellulose (BNC) may serve as an ideal wound dressing, it exhibits no antibacterial properties by itself. Therefore, in the present study BNC was functionalized with the antiseptic drug octenidine. Drug loading and release, mechanical characteristics, biocompatibility, and antimicrobial efficacy were investigated. Octenidine release was based on diffusion and swelling according to the Ritger-Peppas equation and characterized by a time dependent biphasic release profile, with a rapid release in the first 8h, followed by a slower release rate up to 96 h. The comparison between lab-scale and up-scale BNC identified thickness, water content, and the surface area to volume ratio as parameters which have an impact on the control of the release characteristics. Compression and tensile strength remained unchanged upon incorporation of octenidine in BNC. In biological assays, drug-loaded BNC demonstrated high biocompatibility in human keratinocytes and antimicrobial activity against Staphylococcus aureus. In a long-term storage test, the octenidine loaded in BNC was found to be stable, releasable, and biologically active over a period of 6 months without changes. In conclusion, octenidine loaded BNC presents a ready-to-use wound dressing for the treatment of infected wounds that can be stored over 6 months without losing its antibacterial activity.

Clinical characteristics and risk factors of diabetic foot ulcer with multidrug-resistant organism infection

The objective was to determine multidrug-resistant organisms' (MDROs) profile in diabetic foot ulcers (DFU), antibiotic resistance of MDROs, and to find the potential risk factors for infection with MDROs. In 157 patients with DFU admitted to Tianjin Metabolic Disease Hospital, China, from January 2011 to January 2012, microbiological specimens were taken on admission. The patients were divided into 2 groups according to the infection of MDROs. Potential risk factors for MDRO-positive specimens were examined using univariate and multivariate analyses. Seventy-eight MDRO strains were isolated from patients in the MDRO+ group, among which the top 3 were Staphylococcus aureus (16.7%), Enterobacter spp (16.7%), and Pseudomonas aeruginosa (15.4%). Most of the MDROs were resistant to at least 8 kinds of commonly used antibiotics. Gram-negative MDROs showed 23% to 50% resistance to third-generation cephalosporins. The resistant rates of Gram-positive MDROs to fluoroquinolone were more than 70%; penicillin and semisynthetic penicillin were 57% to 100% resistant. Previous hospitalization (odds ratio [OR] = 3.000; 95% confidence interval [CI] = 1.100-8.182; P = .032), previous duration of antibiotic therapy (OR = 1.078; 95% CI = 1.001-1.160; P = .046), ulcer type (OR = 7.185; 95% CI = 2.115-24.408; P = .002), ulcer size (OR = 1.403; 95% CI = 1.042-1.888; P = .026), and osteomyelitis (OR = 3.390; 95% CI = 1.178-9.756; P = .024) were associated with MDRO infection in patients with DFU.

Diversity of methicillin-resistant Staphylococcus aureus strains isolated from residents of 26 nursing homes in Orange County, California

Nursing homes represent a unique and important methicillin-resistant Staphylococcus aureus (MRSA) reservoir. Not only are strains imported from hospitals and the community, strains can be transported back into these settings from nursing homes. Since MRSA bacteria are prevalent in nursing homes and yet relatively poorly studied in this setting, a multicenter, regional assessment of the frequency and diversity of MRSA in the nursing home reservoir was carried out and compared to that of the MRSA from hospitals in the same region. The prospective study collected MRSA from nasal swabbing of residents of 26 nursing homes in Orange County, California, and characterized each isolate by spa typing. A total of 837 MRSA isolates were collected from the nursing homes. Estimates of admission prevalence and point prevalence of MRSA were 16% and 26%, respectively. The spa type genetic diversity was heterogeneous between nursing homes and significantly higher overall (77%) than the diversity in Orange County hospitals (72%). MRSA burden in nursing homes appears largely due to importation from hospitals. As seen in Orange County hospitals, USA300 (sequence type 8 [ST8]/t008), USA100 (ST5/t002), and a USA100 variant (ST5/t242) were the dominant MRSA clones in Orange County nursing homes, representing 83% of all isolates, although the USA100 variant was predominant in nursing homes, whereas USA300 was predominant in hospitals. Control strategies tailored to the complex problem of MRSA transmission and infection in nursing homes are needed in order to minimize the impact of this unique reservoir on the overall regional MRSA burden.

Diagnosis and management of infection in the diabetic foot

Foot infections are common in persons with diabetes mellitus. Most diabetic foot infections occur in a foot ulcer, which serves as a point of entry for pathogens. Unchecked, infection can spread contiguously to involve underlying tissues, including bone. A diabetic foot infection is often the pivotal event leading to lower extremity amputation, which account for about 60% of all amputations in developed countries. Given the crucial role infections play in the cascade toward amputation, all clinicians who see diabetic patients should have at least a basic understanding of how to diagnose and treat this problem.

Global fluoroquinolone resistance epidemiology and implictions for clinical use

This paper on the fluoroquinolone resistance epidemiology stratifies the data according to the different prescription patterns by either primary or tertiary caregivers and by indication. Global surveillance studies demonstrate that fluoroquinolone resistance rates increased in the past years in almost all bacterial species except S. pneumoniae and H. influenzae, causing community-acquired respiratory tract infections. However, 10 to 30% of these isolates harbored first-step mutations conferring low level fluoroquinolone resistance. Fluoroquinolone resistance increased in Enterobacteriaceae causing community acquired or healthcare associated urinary tract infections and intraabdominal infections, exceeding 50% in some parts of the world, particularly in Asia. One to two-thirds of Enterobacteriaceae producing extended spectrum β-lactamases were fluoroquinolone resistant too. Furthermore, fluoroquinolones select for methicillin resistance in Staphylococci. Neisseria gonorrhoeae acquired fluoroquinolone resistance rapidly; actual resistance rates are highly variable and can be as high as almost 100%, particularly in Asia, whereas resistance rates in Europe and North America range from <10% in rural areas to >30% in established sexual networks. In general, the continued increase in fluoroquinolone resistance affects patient management and necessitates changes in some guidelines, for example, treatment of urinary tract, intra-abdominal, skin and skin structure infections, and traveller's diarrhea, or even precludes the use in indications like sexually transmitted diseases and enteric fever.

Microbial profile and utility of soft tissue, pus, and bone cultures in diagnosing diabetic foot infections

OBJECTIVE

This study assessed the utility of pus, soft tissue, and bone specimens in diagnosing diabetic foot infections and the spectrum of the microbial flora and in vitro susceptibility to antibiotics.

SUBJECTS AND METHODS

This prospective study was carried out in 60 consecutive patients with diabetes having clinically infected foot ulcers. Detailed history, physical examination, and investigation were carried out to diagnose the presence of osteomyelitis and the microbial etiology of foot ulcers. Foot ulcers were classified as per Wagner's classification. Soft tissue, pus, and bone samples were obtained and cultured for aerobic and anaerobic bacteria, and antimicrobial susceptibility testing was carried out as per the standard protocol.

RESULTS

Causative bacteria were isolated in 55 of 60 patients, and 157 isolates were cultured from 117 specimens with an average of 1.34 isolates per cases; however, the number of isolates per specimen did not differ among the various types of samples (P=0.78). Pus and soft tissue had predominantly polymicrobial flora, whereas bone infections were monomicrobial. The isolates from soft tissue specimens were different from those from bone and pus in 57% and 54% of cases, respectively. The common bacterial isolates from 117 specimens included Escherichia coli (21%) and Proteus species (15.9%). Nearly 70% of Staphylococcus aureus isolates were methicillin sensitive. All S. aureus and Enterococcus isolates were sensitive to vancomycin. Susceptibility of Gram-negative organisms to ciprofloxacin was 50%.

CONCLUSIONS

Diabetic foot infections are mostly polymicrobial with Gram-negative predominance. Multiple sampling from superficial and deep tissues, including bone, when involved, yields more relevant information diagnostically and therapeutically.

A case report of a multi-drug resistant bacterial infection in a diabetic patient treated in northeast Brazil

Diabetes mellitus is one of the most critical health conditions around the world, not only in terms of the number of affected people, disability, and premature mortality, but also in regards to the health care costs involved in controlling and treating its complications. Among the most constant ailments the diabetic patient suffers is the diabetic foot, defined as any infection, ulceration, and/or necrosis of deep tissues associated with neurological abnormalities and various degrees of peripheral vascular disease of the lower limbs. Diabetic foot ulcerations have become a major and increasing public health concern and its associated morbidities, impairment of the patients' quality of life, and the implied costs for management have attracted the attention of numerous health care providers. In this case report, the authors review a unique presentation of a polymicrobial infection of a multi-drug resistant character species formed by oxacillin-resistant Staphylococcus aureus, Acinetobacter baumannii and Acinetobacter lwoffii.

Study of plasmid-mediated extended-spectrum β-lactamase-producing strains of enterobacteriaceae, isolated from diabetic foot infections in a North Indian tertiary-care hospital

AIM

This study evaluated the incidence and factors responsible for plasmid-mediated extended-spectrum β-lactamase (ESBL) infection among patients with diabetic foot ulcer (DFU).

SUBJECTS AND METHODS

A prospective study was conducted on 162 DFU inpatients treated in a multidisciplinary-based diabetes and endocrinology center at Jawaharlal Nehru Medical College of Aligarh Muslim University, Aligarh, India, during the period of December 2008-March 2011. Detailed history and patient's profile, grade of DFU, co-morbidities and complications, laboratory data, and final outcome were collected. Standard methods were used for culture identification, sensitivity testing, and ESBL detection. Polymerase chain reaction for bla genes was performed, and the risk factors for bla gene positivity were determined by univariate analysis with 95% confidence interval.

RESULTS

In total, 127 (78.3%) Enterobacteriaceae members were isolated. The most common isolate was Escherichia coli (71; 55.9%), followed by Klebsiella sp. (33; 25.9%) and Proteus sp. (13; 10.2%). By phenotypic methods, 67.8% were ESBL producers. In the molecular detection of ESBLs, 81.9% were found to be positive for the bla gene, of which bla(CTX-M) showed 81.8% positivity, followed by bla(TEM) (50%) and bla(SHV) (46.9%). In a univariate analysis, bla gene-positive status was associated with low-density lipoprotein-cholesterol (>100 mg/dL) (P<0.004, odds ratio 13.4, relative risk 8.65) and triglycerides (>200 mg/dL) (P<0.003, odds ratio 6.5, relative risk 4.11).

CONCLUSION

ESBL constitutes a major threat to currently available β-lactam therapy, leading to complications in DFUs. Aminoglycosides, cephalosporin, and β-lactam inhibitor drugs would probably be more appropriate empirical agents after establishing the patient's history of previous antibiotic use. The detection of ESBL should be done on a routine basis.

Resistance surveillance studies: a multifaceted problem--the fluoroquinolone example

INTRODUCTION

This review summarizes data on the fluoroquinolone resistance epidemiology published in the previous 5 years.

MATERIALS AND METHODS

The data reviewed are stratified according to the different prescription patterns by either primary- or tertiary-care givers and by indication. Global surveillance studies demonstrate that fluoroquinolone- resistance rates increased in the past several years in almost all bacterial species except Staphylococcus pneumoniae and Haemophilus influenzae causing community-acquired respiratory tract infections (CARTIs), as well as Enterobacteriaceae causing community-acquired urinary tract infections. Geographically and quantitatively varying fluoroquinolone resistance rates were recorded among Gram-positive and Gram-negative pathogens causing healthcare-associated respiratory tract infections. One- to two-thirds of Enterobacteriaceae producing extended-spectrum β-lactamases (ESBLs) were fluoroquinolone resistant too, thus, limiting the fluoroquinolone use in the treatment of community- as well as healthcare-acquired urinary tract and intra-abdominal infections. The remaining ESBL-producing or plasmid-mediated quinolone resistance mechanisms harboring Enterobacteriaceae were low-level quinolone resistant. Furthermore, 10-30 % of H. influenzae and S. pneumoniae causing CARTIs harbored first-step quinolone resistance determining region (QRDR) mutations. These mutants pass susceptibility testing unnoticed and are primed to acquire high-level fluoroquinolone resistance rapidly, thus, putting the patient at risk. The continued increase in fluoroquinolone resistance affects patient management and necessitates changes in some current guidelines for the treatment of intra-abdominal infections or even precludes the use of fluoroquinolones in certain indications like gonorrhea and pelvic inflammatory diseases in those geographic areas in which fluoroquinolone resistance rates and/or ESBL production is high. Fluoroquinolone resistance has been selected among the commensal flora colonizing the gut, nose, oropharynx, and skin, so that horizontal gene transfer between the commensal flora and the offending pathogen as well as inter- and intraspecies recombinations contribute to the emergence and spread of fluoroquinolone resistance among pathogenic streptococci. Although interspecies recombinations are not yet the major cause for the emergence of fluoroquinolone resistance, its existence indicates that a large reservoir of fluoroquinolone resistance exists. Thus, a scenario resembling that of a worldwide spread of β-lactam resistance in pneumococci is conceivable. However, many resistance surveillance studies suffer from inaccuracies like the sampling of a selected patient population, restricted geographical sampling, and undefined requirements of the user, so that the results are biased. The number of national centers is most often limited with one to two participating laboratories, so that such studies are point prevalence but not surveillance studies. Selected samples are analyzed predominantly as either hospitalized patients or patients at risk or those in whom therapy failed are sampled; however, fluoroquinolones are most frequently prescribed by the general practitioner. Selected sampling results in a significant over-estimation of fluoroquinolone resistance in outpatients. Furthermore, the requirements of the users are often not met; the prescribing physician, the microbiologist, the infection control specialist, public health and regulatory authorities, and the pharmaceutical industry have diverse interests, which, however, are not addressed by different designs of a surveillance study. Tools should be developed to provide customer-specific datasets.

CONCLUSION

Consequently, most surveillance studies suffer from well recognized but uncorrected biases or inaccuracies. Nevertheless, they provide important information that allows the identification of trends in pathogen incidence and antimicrobial resistance.

A study of the microbiology of diabetic foot infections in a teaching hospital in Kuwait

The purpose of this study was to determine the microbiological profile of diabetic foot infections (DFIs) and assess the antibiotic susceptibility of the causative agents. Data were obtained from a retrospective analysis of DFI samples collected from June 2007 to July 2008. Specimens were cultured using optimal aerobic and anaerobic microbiological techniques, and antibiotic susceptibility testing was performed according to the methods recommended by the Clinical and Laboratory Standards Institute (CLSI). Extended-spectrum β-lactamase (ESBL) production was measured using the double disk synergy test and the ESBL Etest. A total of 440 patients were diagnosed with DFIs during this period, and a total of 777 pathogens were isolated from these patients with an average of 1.8 pathogens per lesion. We isolated more Gram-negative pathogens (51.2%) than Gram-positive pathogens (32.3%) or anaerobes (15.3%). Polymicrobial infection was identified in 75% of the patients. The predominant organisms isolated were members of the Enterobacteriaceae family (28.5%), Pseudomonas aeruginosa (17.4%), Staphylococcus aureus (11.8%), methicillin-resistant S. aureus (7.7%), anaerobic Gram-negative organisms (10.8%), and Enterococcus spp. (7%). Vancomycin was the most effective treatment for Gram-positive bacteria, and imipenem, piperacillin-tazobactam and amikacin were the most effective treatments for the Gram-negative bacteria. In conclusion, DFI is common among diabetic patients in Kuwait, and most of the cases evaluated in this study displayed polymicrobial etiology. The majority of isolates were multi-drug resistant. The data gathered in this study will be beneficial for future determinations of empirical therapy policies for the management of DFIs.

The impact of creatinine clearance on the outcome of diabetic foot ulcers in north Indian tertiary care hospital

AIM

Wound healing has been reported to be poor in diabetic patients with impaired kidney functions that usually accompanies retinopathy and neuropathy. The insensitive foot is vulnerable to repeated trauma and development of ulcer precedes 70-80% of non-traumatic lower extremity amputation. The present study was aimed to study the impact of creatinine clearance (CCre) on the outcome of diabetic foot ulcers (DFU).

MATERIALS AND METHODS

Data from 162 DFU patients admitted to Rajiv Gandhi Centre for Diabetes and Endocrinology of J.N. Medical College, Aligarh Muslim University, Aligarh, India, between December 2009 and March 2011 were analyzed. Detailed history and patient's profile, grade of DFU, co-morbidities and complications, laboratory data, microbiological profile and final outcome were collected. CCre was calculated according to MDRD formula.

RESULTS

The study revealed that, DFU healing was worst in patients with decreased CCre than in those who had normal CCre. Other factors associated with poor outcome were, higher grade of ulcer, infection type (subcutaneous and osteomyelitis) and biofilm infection. Amputation rates were also found to be higher in those with poor renal functions.

CONCLUSIONS

The results suggest that CCre is an important factor affecting wound healing in patients with DFUs. The automatic reporting of eGFR each time a serum creatinine concentration is requested will increase the awareness of significant kidney dysfunction in clinical practice especially in DFU patients and appropriate measures will improve the outcome.

Antimicrobial activity of clinically used antiseptics and wound irrigating agents in combination with wound dressings

BACKGROUND

A primary strategy for preventing and treating wound infection in chronic wounds is the use of topical antiseptics and wound irrigating agents. However, their interaction with commonly used wound dressings has not yet been investigated. In this study, the authors analyzed the antimicrobial activity of antiseptics and wound irrigating agents used with commercially available wound dressings.

METHODS

Five clinically used antiseptics and wound irrigating agents (Prontosan, Lavasept, Braunol, Octenisept, and Betaisodona) were tested in the presence or absence of 42 wound dressings against Staphylococcus aureus. The determination of antibacterial activity was performed by disk diffusion assay.

RESULTS

Povidone-iodine-based products showed sufficient antimicrobial activity in 64 to 78 percent of the combinations assessed (p > 0.01). The octenidine derivate Octenisept showed sufficient antimicrobial activity in 54 percent of combinations. Polyhexamethylene biguanide derivatives demonstrated sufficient antimicrobial activity in 32 percent of the combinations.

CONCLUSION

This study revealed that commonly used wound dressings dramatically reduce antibacterial activity of clinically used antiseptics and wound irrigating agents in vitro.

Metallo Beta lactamase producing pseudomonas aeruginosa and its association with diabetic foot

Pseudomonas aeruginosa strains that produce metallo beta lactamases (MBLs) are becoming increasingly prevalent in wound infections. The aim of the present study is to determine the clinical features, incidence, and to find out the antimicrobial susceptibility pattern of Pseudomonas aeruginosa in diabetic foot infections. Pus samples for bacterial culture were collected from 310 patients admitted with diabetic foot infections. Antimicrobial sensitivity testing was performed by the Kirby-Bauer disc diffusion method. Carbapenem resistance screening and confirmation of MBL was done by the modified imipenem-ethylenediaminetetraacetic acid (EDTA) double disc synergy test. A total of 54 Pseudomonas aeruginosa was isolated from 310 diabetic foot cases. Males were affected more than females with an M:F ratio of 1.6:1. Most patients belonged to the fifth decade of life with a mean age of 49 ± 16.8 years. All the patients were previously diagnosed with diabetes mellitus with duration of the disease at 16 ± 10.2 years and 63% were prescribed oral hypoglycaemic agents. Wound characteristics were classified according to Wagner's classification majority of Pseudomonas aeruginosa were isolated from Wagner's II and III grade wound. A number of 26 (89.7%) patients underwent debridement, while 9 (31%) patients underwent toe disarticulation, and 7 (24.1%) patients underwent below-the-knee (BKA) amputation. Antibiotic sensitivity testing revealed 20.3% of Pseudomonas aeruginosa were resistance to carbapenem and 81.8% of these were MBL mediated resistance. Infection with multi drug resistance organisms (MDROs) is common in diabetic foot ulcers and is associated with inadequate glycemic control and increased requirement for surgical treatment. There is a need for continuous surveillance of resistant bacteria to provide the basis for empirical therapy and reduce the risk of complications.

High-Glucose Environment Inhibits p38MAPK Signaling and Reduces Human β-Defensin-3 Expression [corrected] in Keratinocytes

Diabetes mellitus is characterized by elevated plasma glucose and increased rates of skin infections. Altered immune responses have been suggested to contribute to this prevalent complication, which involves microbial invasion. In this study we explored the effects of a high-glucose environment on the innate immunity of keratinocytes by focusing on β defensin-3 (BD3) using in vivo and in vitro models. Our results demonstrated that the perilesional skins of diabetic rats failed to show enhanced BD3 expression after wounding. In addition, high-glucose treatment reduced human BD3 (hBD3) expression of cultured human keratinocytes. This pathogenic process involved inhibition of p38MAPK signaling, an event that resulted from increased formation of advanced glycation end products. On the other hand, toll-like receptor-2 expression and function of cultured keratinocytes were not significantly affected by high-glucose treatment. In summary, high-glucose conditions inhibited the BD3 expression of epidermal keratinocytes, which in turn contributed to the frequent occurrences of infection associated with diabetic wounding.

Clinico-microbiological study and antimicrobial drug resistance profile of diabetic foot infections in North India

The study was carried out in diabetic patients with foot ulcer to determine the microbiological profile of infected ulcer, antibiotic resistance of the isolates and to find out the potential risk factors for infection with multidrug resistance and the outcome of these infections. A detailed clinical history and physical examination was carried out in each patient. Pus samples for bacterial culture were collected from 102 patients admitted with diabetic foot infections. All patients had ulcer with Texas grades 1-3. Seventeen patients (16.6%) had coexisting osteomyelitis. Aerobic gram negative bacilli were tested for extended spectrum β lactamase (ESBL) production by phenotypic and genotypic methods. Staphylococcus isolates were tested for susceptibility to oxacillin and cefoxitin by disk method. Potential risk factors for MDRO positive samples were explored. Gram negative aerobes were most frequently isolated (63.8%), followed by gram positive aerobes (36.1%) and anaerobes (31.4%). Forty five percent of patients were positive for MDROs. ESBL production and methicillin resistant was noted in 68.5% and 43.2% of bacterial isolates respectively. 34.5% gram negative strains were positive for bla(CTX-M) gene followed by bla(SHV) (23%) and bla(TEM) (7.4%). Among the anaerobic organism 17(31.4%) from 54 patients, most commonly isolated were Peptostreptococcus sp. (35.2%). MDRO positive status was associated with the presence of neuropathy (P<0.001), osteomyelitis (P<0.03), and ulcer size >4 cm(2) (P<0.01) [corrected] but not with patients characteristic, ulcer type and type of diabetes, or duration of hospital stay. Poor glycemic control in 68.6% patients, duration of infection>1 month (36.2%) and ulcer size >4 cm(2) (75.4%) were independently associated with risk of MDR organisms infection.

Changing microbiological profile of pathogenic bacteria in diabetic foot infections: time for a rethink on which empirical therapy to choose?

AIMS/HYPOTHESIS

We studied the bacterial aetiology and antibiotic sensitivity pattern of diabetic foot ulcers in India.

METHODS

Records of 447 hospitalised patients between 1991 and 2008 were retrospectively analysed between two time periods (before and after 1999) to compare bacterial aetiology and antimicrobial sensitivity patterns. The first three consecutive cultures from the same wound during treatment were evaluated.

RESULTS

Of 1,632 cultures, 66% were polymicrobial, 23% monomicrobial and 11% sterile. In the monomicrobial group, 14% (n = 228) of cultures were Gram-negative, whereas 9% (n = 147) were Gram-positive. The most common pathogens in the first culture were Pseudomonas aeruginosa (20.1%), Staphylococcus aureus (17.2%) and Escherichia coli (16.3%). Results for the third cultures showed persistence of P. aeruginosa (15.3%) and E. coli (14.2%). Gram-negative isolates dominated over Gram-positive ones (25.3% vs 15.1%, p < 0.05). Antibiotic sensitivity patterns before and after 1999 were: piperacillin-tazobactam 74% vs 66% (p < 0.005), imipenem 77% vs 85% (NS), cefoperazone-sulbactam 47% vs 44% (p < 0.005), amikacin 62% vs 78% (NS), ceftriaxone 41% vs 36% (p < 0.005), amoxicillin-clavulanate 51% vs 43% (p < 0.05) and clindamycin 43% vs 36% (p < 0.005), respectively.

CONCLUSIONS/INTERPRETATION

Unlike in the West, in India Gram-negative bacteria were found to have always been dominant in the wounds of patients with diabetic foot infections. Infection with polymicrobial multidrug-resistant Gram-negative bacilli is common. The policy of empirical antimicrobial therapy at tertiary care needs to be changed.

Methicillin-resistant Staphylococcus aureus in diabetic foot infections

Diabetic foot ulcers are often complicated by infection. Among pathogens, Staphylococcus aureus predominates. The prevalence of methicillin-resistant S. aureus (MRSA) in infected foot ulcers is 15-30% and there is an alarming trend for increase in many countries. There are also data that recognize new strains of MRSA that are resistant to vancomycin. The risk for MRSA isolation increases in the presence of osteomyelitis, nasal carriage of MRSA, prior use of antibacterials or hospitalization, larger ulcer size and longer duration of the ulcer. The need for amputation and surgical debridement increases in patients infected with MRSA. Infections of mild or moderate severity caused by community-acquired MRSA can be treated with cotrimoxazole (trimethoprim/sulfamethoxazole), doxycycline or clindamycin when susceptibility results are available, while severe community-acquired or hospital-acquired MRSA infections should be managed with glycopeptides, linezolide or daptomycin. Dalbavancin, tigecycline and ceftobiprole are newer promising antimicrobial agents active against MRSA that may also have a role in the treatment of foot infections if more data on their efficacy and safety become available.

Meticillin-resistant Staphylococcus aureus isolated from foot ulcers in diabetic patients in a Chinese care hospital: risk factors for infection and prevalence

A retrospective case–control study of 118 (male : female, 68 : 50) Chinese type 2 diabetic patients with foot ulcers (Wagner's grade 3–5) was conducted to determine the prevalence and risk factors for meticillin-resistant Staphylococcus aureus (MRSA) infection in relation to the original community or hospital parameters. Ulcer specimens were processed for Gram staining, aerobic culture and antimicrobial susceptibility testing. Staphylococcus species were tested for meticillin resistance using oxacillin. S. aureus was the most frequent pathogen (25.6 %) in diabetic patient specimens (160 isolates), and a high proportion of S. aureus isolates were MRSA (63.4 %). A high percentage of S. aureus isolates (65.4 %) satisfied the definition for hospital-associated MRSA (HA-MRSA) infection. The size of ulcers [adjusted odds ratio (OR) 1.61; 95 % confidence interval (CI) 1.22–2.12] and osteomyelitis (adjusted OR 18.51, 95 % CI 2.50–137.21) were independent predictors of MRSA infection. The HA-MRSA group had a significantly different distribution from the community-associated MRSA group with respect to age, history of diabetes and length of hospital stay (all P<0.001). Neuropathy, vascular disease (all P=0.049) and osteomyelitis (P=0.026) were the most common underlying conditions observed in the HA-MRSA group. This study contributes to the establishment of precautions against the emergence of MRSA including MRSA acquired from different sources among the Chinese population with diabetic foot ulcers based on their original or clinical parameters.

Predictive model of short-term amputation during hospitalization of patients due to acute diabetic foot infections

INTRODUCTION

Factors predicting short-term amputation during hospital treatment of patients admitted for acute diabetic foot infections are of interest for clinicians managing the acute episode.

METHODS

A retrospective clinical records analysis of 78 consecutive patients hospitalized for acute diabetic foot infections was performed to identify predictive factors for short-term amputation by comparing the data of patients who ultimately required amputation and those who did not. Clinical/epidemiological, laboratory, imaging, and treatment variables were comparatively analyzed. A logistic regression model was performed, with amputation as the dependent variable and factors showing significant differences in the bivariate analysis as independent variables. A prediction score was calculated (and validated by ROC curve analysis) using beta coefficients for significant variables in the regression analysis to predict amputation.

RESULTS

Of the 78 patients (70.5% with peripheral vasculopathy) included, 26 ultimately required amputation. In the bivariate analysis, white blood cell count, previous homolateral lesions, odor, lesion depth, sedimentation rate, Wagner ulcer grade, and arterial obstruction on Doppler study were significantly higher in patients ending in amputation. In the multivariate analysis, the risk of amputation was increased only by Wagner grade 4 or 5 (20-fold higher), obstruction (12.5-fold higher), and elevated sedimentation rate (6% higher per unit). Logistic regression predicted outcome in 76.9% of patients who underwent amputation and 92.3% of those who did not.

CONCLUSION

The score calculated using beta coefficients for significant variables in the regression model (Wagner grades 4 and 5, obstruction on Doppler, and elevated sedimentation rate for the clinical, imaging, and laboratory data, respectively) correctly predicted amputation during hospital management of acute diabetic foot infections.

[A comparative in vitro study of cell toxicity of clinically used antiseptics]

PURPOSE

Local skin antiseptics are the standard of care for chronic and non-healing wounds. However, little is known about their potential toxic properties. This study investigates the impact of three commercially available and widely used antiseptics on vitality and proliferation of human cutaneous cells.

MATERIAL AND METHODS

Three antiseptics, Lavasept (PHMB), Octenisept (octenidine) and Betaisodona (PVP-iodine) were tested for their cytotoxic effects towards HaCaT cells, primary human keratinocytes and fibroblasts using MTT assay and BrDU ELISA.

RESULTS

Lavasept showed only slight to moderate toxic effects on cellular vitality and proliferation. Ocentisept and Betaisodona induced severe reduction of cell vitality (p<0.05) to 0% surviving fibroblasts at 7.5% (Betaisodona) and 12.5% Octenisept, respectively. Furthermore, poliferative activity was reduced to 0% in keratinocytes at 7.5% concentration of Betaisodona and Ocentisept.

CONCLUSION

This study shows that frequently used wound- and skin antiseptics show severe cytotoxic effects towards cutaneous cells. Furthermore, antimicrobial efficacy and toxic properties must be included in the clinical decision process for optimal therapy of chronic wounds. The PHMB solution Lavasept showed best results regarding toxicity in this study.

Evaluation of toxic side effects of clinically used skin antiseptics in vitro

BACKGROUND

Skin antiseptics are widely used in health-care worldwide. However, there is a need to determine cytotoxicity of these medications on wounds. The aim of this study was to evaluate cytotoxic effects of five clinically used antiseptics on human skin cells.

MATERIAL AND METHODS

Five clinically used skin antiseptics (Prontosan, Lavasept, Braunol, Octenisept, and Betaisodona) were tested. The minimal inhibitory concentration was determined against Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa, and Escherichia coli). The cytotoxic effects on primary keratinocytes, fibroblasts, and a HaCaT cell line were determined (MTT-assay and BrdU-ELISA) at a wide range of concentrations.

RESULTS

The agents tested showed effective antibacterial properties (Octenisept, Lavasept, and Prontosan showed higher efficacy than Braunol and Betaisodona) and different degrees of cytotoxicity. Lavasept and Prontosan demonstrated less toxicity on primary human fibroblasts and keratinocytes, whereas Octenisept, Betaisodona, and Braunol showed a significant (P<0.05) decrease in cell viability to 0% on keratinocytes at concentrations of 4%, 7.5%, and 12.5%, and on fibroblasts at 7.5% and 10%, respectively.

CONCLUSION

Due to the cytotoxic effect of some antiseptics on human skin cells, it is advised that health care professionals balance the cytotoxicity of the medication, their antiseptic properties, and the severity of colonization when selecting a wound care antiseptic. In this study, Lavasept and Prontosan showed best result regarding antibacterial efficacy and cell toxicity.

Human beta-defensin-3 promotes wound healing in infected diabetic wounds

BACKGROUND

Infected wounds present a major complication in patients with diabetes. Staphylococcus aureus is the most common single isolate in diabetic wounds. Human beta-defensin (hBD)-3 is antimicrobial active and appears to play a key role in the immune response. The present study aimed to analyse the effect of hBD-3 expression in a model of infected diabetic wounds.

METHODS

Excisional wounds were created on the backs of Yorkshire pigs and Ad5-CMV-hBD-3 vectors were microseeded. Wounds were inoculated with S. aureus, covered with a polyurethane chamber and analysed for transgene expression, bacterial infection, re-epithelialization, wound contraction, wound fluid production and blood vessel formation.

RESULTS

hBD-3-treated wounds showed a total bacterial load of 2.1 x 10(8) colony-forming units (CFU)/g tissue, versus 1.3 x 10(9) CFU/g tissue for controls (p < 0.001) at day 4. At day 12, no statistical difference could be detected. Re-epithelialization showed 75 +/- 15% wound closure for hBD-3 expressing wounds and 50 +/- 16% for controls (p < 0.01). hBD-3 expression was in the range 15-20 ng/ml of wound fluid during day 1-4. The lower dose of 2 x 10(9) Ad5-CMV-hBD-3 showed no effect, suggesting a dose dependency for hBD-3.

CONCLUSIONS

In the present study, we show that hBD-3 expression significantly promotes wound closure in S. aureus infected diabetic wounds in a preclinical large-animal model. Furthermore, a ten-fold reduction of bacterial growth on day 4 was detected. These findings indicate that beta-defensin-3 may play a major role in diabetic wound healing and wound infections.

The use of ertapenem for the treatment of lower extremity infections

Lower extremity infections are a growing challenge. Moderate to severe infections are frequently polymicrobial in nature and require appropriate parenteral antibiotic therapy. Ideally, empiric treatment should be broad spectrum in coverage, simplistic in use, and economically reasonable for the patient and the health care system. This article retrospectively reviewed the outcomes of 230 patients, 159 (69.13%) of whom were diabetic, who were admitted with lower extremity infections and who were empirically treated with ertapenem. Ertapenem was well tolerated with a low adverse effect profile. We found a 79.13% rate (182 of 230 patients) of favorable outcome with this regimen, which is comparable to other published studies that have looked at the use of this agent. Ertapenem is a once-daily, broad-spectrum carbapenem antibiotic indicated for the treatment of complicated skin and skin-structure infections (cSSSI). Ertapenem is an appropriate choice for empiric antibiotic therapy of lower extremity infections.

LEVEL OF CLINICAL EVIDENCE

2.

Wound bioburden and infection-related complications in diabetic foot ulcers

The identification and diagnosis of diabetic foot ulcer (DFU) infections remains a complex problem. Because inflammatory responses to microbial invasion may be diminished in persons with diabetes, clinical signs of infection are often absent in persons with DFUs when infection is limited to localized tissue. In the absence of these clinical signs, microbial load is believed to be the best indicator of infection. Some researchers, however, believe microbial load to be insignificant and type of organism growing in the ulcer to be most important. Previous studies on the microbiology of DFUs have not provided enough evidence to determine the microbiological parameters of importance.Infection-related complications of DFUs include wound deterioration, osteomyelitis, and amputation. Risk factors for amputation include age, peripheral vascular disease, low transcutaneous oxygen, smoking, and poor glycemic control. These risk factors are best measured directly with physiological measures of arterial perfusion, glycemic control, sensory neuropathy, plantar pressures, and activity level and by controlling off-loading. DFU bioburden has not been examined as a risk factor for infection-related complications. To address the relationship between wound bioburden and the development of infection-related complications in DFUs, tightly controlled prospective studies based on clearly defined, valid measures of wound bioburden and wound outcomes are needed. This article reviews the literature and proposes a model of hypothesized relationships between wound bioburden-including microbial load, microbial diversity, and pathogenicity of organisms-and the development of infection-related complications.

The diabetic foot

Diabetes is reaching epidemic proportions and with it carries the risk of complications. Disease of the foot is among one of the most feared complications of diabetes. The ultimate endpoint of diabetic foot disease is amputation, which is associated with significant morbidity and mortality, besides having immense social, psychological and financial consequences. As the majority of amputations are preceded by foot ulceration, it is crucial to identify those at an increased risk. Diabetic foot ulcers may develop as a result of neuropathy, ischaemia or both and when infection complicates a foot ulcer, the combination can become limb and life threatening. Structural abnormalities such as calluses, bunions, hammer toes, claw toes, flat foot and rocker bottom foot need to be identified and managed.

Enhanced susceptibility to infections in a diabetic wound healing model

Background

Wound infection is a common complication in diabetic patients. The progressive spread of infections and development of drug-resistant strains underline the need for further insights into bacterial behavior in the host in order to develop new therapeutic strategies. The aim of our study was to develop a large animal model suitable for monitoring the development and effect of bacterial infections in diabetic wounds.

Methods

Fourteen excisional wounds were created on the dorsum of diabetic and non-diabetic Yorkshire pigs and sealed with polyurethane chambers. Wounds were either inoculated with 2 × 10⁸ Colony-Forming Units (CFU) of Staphylococcus aureus or injected with 0.9% sterile saline. Blood glucose was monitored daily, and wound fluid was collected for bacterial quantification and measurement of glucose concentration. Tissue biopsies for microbiological and histological analysis were performed at days 4, 8, and 12. Wounds were assessed for reepithelialization and wound contraction.

Results

Diabetic wounds showed a sustained significant infection (>10⁵ CFU/g tissue) compared to non-diabetic wounds (p < 0.05) over the whole time course of the experiment. S. aureus-inoculated diabetic wounds showed tissue infection with up to 8 × 10⁷ CFU/g wound tissue. Non-diabetic wounds showed high bacterial counts at day 4 followed by a decrease and no apparent infection at day 12. Epidermal healing in S. aureus-inoculated diabetic wounds showed a significant delay compared with non-inoculated diabetic wounds (59% versus 84%; p < 0.05) and were highly significant compared with healing in non-diabetic wounds (97%; p < 0.001).

Conclusion

Diabetic wounds developed significantly more sustained infection than non-diabetic wounds. S. aureus inoculation leads to invasive infection and significant wound healing delay and promotes invasive co-infection with endogenous bacteria. This novel wound healing model provides the opportunity to closely assess infections during diabetic wound healing and to monitor the effect of therapeutical agents in vivo.