Prevalence of Multiple Antibiotic Resistant Infections in Diabetic versus Nondiabetic Wounds

The biogeography of polymicrobial infection

Microbial communities are spatially organized in both the environment and the human body. Although patterns exhibited by these communities are described by microbial biogeography, this discipline has previously only considered large-scale, global patterns. By contrast, the fine-scale positioning of a pathogen within an infection site can greatly alter its virulence potential. In this Review, we highlight the importance of considering spatial positioning in the study of polymicrobial infections and discuss targeting biogeography as a therapeutic strategy.

Lactobacillus rhamnosus GG Lysate Increases Re-Epithelialization of Keratinocyte Scratch Assays by Promoting Migration

A limited number of studies have investigated the potential of probiotics to promote wound healing in the digestive tract. The aim of the current investigation was to determine whether probiotic bacteria or their extracts could be beneficial in cutaneous wound healing. A keratinocyte monolayer scratch assay was used to assess re-epithelialization; which comprises keratinocyte proliferation and migration. Primary human keratinocyte monolayers were scratched then exposed to lysates of Lactobacillus (L) rhamnosus GG, L. reuteri, L. plantarum or L. fermentum. Re-epithelialization of treated monolayers was compared to that of untreated controls. Lysates of L. rhamnosus GG and L. reuteri significantly increased the rate of re-epithelialization, with L. rhamnosus GG being the most efficacious. L. reuteri increased keratinocyte proliferation while L. rhamnosus GG lysate significantly increased proliferation and migration. Microarray analysis of L. rhamnosus GG treated scratches showed increased expression of multiple genes including the chemokine CXCL2 and its receptor CXCR2. These are involved in normal wound healing where they stimulate keratinocyte proliferation and/or migration. Increased protein expression of both CXCL2 and CXCR2 were confirmed by ELISA and immunoblotting. These data demonstrate that L. rhamnosus GG lysate accelerates re-epithelialization of keratinocyte scratch assays, potentially via chemokine receptor pairs that induce keratinocyte migration.

Second Annual Meeting of the International Society of Pediatric Wound Care

The overarching goals of the International Society of Pediatric Wound Care (ISPeW) are to (1) set global standards for the assessment and treatment of pediatric wounds of varying etiologies; (2) provide a forum for international interprofessional collaboration among healthcare professionals, researchers, educators, and industry leaders dedicated to the care of pediatric wounds; (3) promote and support clinical research focused on the prevention, assessment, and treatment of pediatric wounds; (4) collaborate with wound care organizations worldwide on pediatric wound care issues; and (5) provide evidence-based pediatric wound care education to healthcare professionals, parents, and lay caregivers. This edition of Advances in Wound Care includes some of the work that was presented at the 2014 ISPeW meeting in Rome. The first article by Dr. Romanelli, is an in-depth description of the progression of skin physiology throughout its maturational stages and clinical implication. A cutting edge article by Dr. Timothy King then follows, with regard to scar prevention in postnatal tissues. This is followed by a comprehensive look at debridement techniques in pediatric trauma by Dr. Ankush Gosain. Next, is a cautionary article by Dr. Luca Spazzapan that examines the prevalence of diabetic foot ulcers in children and the potential for an epidemic. The last article in this series is from the keynote speaker, Dr. Amit Geffen, who eloquently examines the use of biomaterials to offload and prevent pediatric pressure ulcers.

Spectrum of bacteria associated with diabetic foot ulcer and biofilm formation: A prospective study

BACKGROUND

India has the world's largest number of diabetics. Non-traumatic lower limb amputation is the most common devastating complication of diabetes, primarily due to diabetic foot ulcers (DFU) and diabetic foot infections (DFI). In India, the incidence of foot ulcers ranges from 8-17 per cent. DFIs are predominantly polymicrobial and multidrug-resistant (MDR) with the ability to form biofilm, which is an important virulence factor and results in treatment failure.

AIMS

The main objectives of the study are to identify the spectrum of multidrug-resistant bacteria associated with these infections, their antibiotic sensitivity pattern, and to detect the biofilm formation.

METHODS

This was a prospective study at a tertiary care hospital. One hundred patients over the age of 18, having chronic diabetic foot ulcer, and attending the surgery outpatient department were included. Samples of pus were collected from deep wounds and processed using standard techniques for culture and sensitivity. Biofilm detection was done. Results were compiled and statistically analysed.

RESULTS

One hundred samples were processed and 82 yielded positive cultures. Staphylococcus aureus was the predominant organism, followed by Pseudomonas aeruginosa. Biofilm formation was seen in 38 (46.34 per cent) of the organisms. Biofilms were formed predominantly by Staphylococcus aureus (20 per cent).

CONCLUSION

The organisms causing chronic diabetic foot ulcers were commonly multidrug-resistant; this was also observed among biofilm formers. Therefore, screening for biofilm formation, along with the usual antibiogram, needs to be performed as a routine procedure in chronic diabetic ulcers to formulate effective treatment strategies for these patients.

Synergistic interactions of Pseudomonas aeruginosa and Staphylococcus aureus in an in vitro wound model

In individuals with polymicrobial infections, microbes often display synergistic interactions that can enhance their colonization, virulence, or persistence. One of the most prevalent types of polymicrobial infection occurs in chronic wounds, where Pseudomonas aeruginosa and Staphylococcus aureus are the two most common causes. Although they are the most commonly associated microbial species in wound infections, very little is known about their interspecies relationship. Evidence suggests that P. aeruginosa-S. aureus coinfections are more virulent than monoculture infection with either species; however, difficulties in growing these two pathogens together in vitro have hampered attempts to uncover the mechanisms involved. Here we describe a simple and clinically relevant in vitro wound model that supported concomitant growth of P. aeruginosa and S. aureus. We observed that the ability of P. aeruginosa and S. aureus to survive antibiotic treatment increased when they were grown together in planktonic cocultures and that antibiotic tolerance was further enhanced when they were grown together in the wound model. We attributed this enhanced tolerance to both the "host-derived" and "bacterium-derived" matrix components. Taken together, our data indicate that P. aeruginosa and S. aureus may benefit each other by coinfecting wounds and that the host-derived matrix may serve as important a role as the bacterium-derived matrix in protecting bacteria from some antibiotics.