A Combination of the Natural Molecules Gallic Acid and Carvacrol Eradicates P. aeruginosa and S. aureus Mature Biofilms

Wound infection, especially the development of bacterial biofilms, delays wound healing and is a major public health concern. Bacteria in biofilms are more tolerant to antimicrobial agents, and new treatments to eradicate mature biofilms are needed. Combining antimicrobial molecules with different mechanisms of action is an attractive strategy to tackle the heterogeneous nature of microbial communities in biofilms. This study focused on three molecules of natural origin: gallic acid (G), carvacrol (K) and curcumin (Q). Their abilities, individually or in combination, to eradicate biofilms were quantified on mono- and dual-species mature biofilms of Pseudomonas aeruginosa and Staphylococcus aureus, the strains most commonly found in infected wounds. G presented biofilm eradicating activity on P. aeruginosa, whereas K had biofilm eradicating activity on S. aureus and P. aeruginosa. Q had no potent biofilm eradicating activity. The combination of G and K increased the effects previously observed on P. aeruginosa biofilm and led to complete eradication of S. aureus biofilm. This combination was also efficient in eradicating a dual-species biofilm of S. aureus and P. aeruginosa. This work demonstrates that K and G used in combination have a strong and synergistic eradicating activity on both mono- and dual-species mature biofilms of S. aureus and P. aeruginosa and may therefore represent an efficient alternative for the treatment of biofilms in wounds.

Properties of interpenetrating polymer networks associating fibrin and silk fibroin networks obtained by a double enzymatic method

Fibrin gels are of interest as biomaterials for regenerative medicine but present poor mechanical properties, undergo fast degradation and strongly contract in presence of cells. To face these drawbacks, a fibrin network can be associated with another polymer network, in an Interpenetrating Polymer Network (IPN) architecture. In this study, we report the properties of an IPN comprising a fibrin (Fb) network and a silk fibroin (SF) network. This IPN is synthesized through the action of 2 enzymes, each one being specific of one protein gelation, i.e. thrombin (Tb) for Fb gelation, and horseradish peroxidase (HRP) for SF gelation. The effective formation of both Fb and SF networks in an IPN architecture was first verified at qualitative and quantitative levels. The resulting IPN was easily manipulable, displayed high viscoelastic properties and showed homogeneous macro- and micro-structure. Then the degradability of the IPN by two proteases, thermolysin (TL) and trypsin (TRY), obeying different mechanisms was presented. Finally, two-dimensional culture of human fibroblasts on the IPN surface induced little material contraction, while fibroblasts showed healthy morphology, displayed high viability and produced mature extracellular matrix (ECM) proteins. Taken together, the results suggest that this new IPN have a strong potential for tissue engineering and regenerative medicine.

Ongoing outbreak of Shigella flexneri serotype 3a in men who have sex with men in England and Wales, data from 2009–2011

Diagnoses of Shigella flexneri in the United Kingdom (UK) are usually travel-related. However, since 2009, there has been an overall increase in UK-acquired cases. The Health Protection Agency has been investigating a national outbreak of S. flexneri detected in 2011 and which is still ongoing. Cases occurred mostly in men who have sex with men and were of serotype 3a. The investigation aimed at obtaining epidemiological data to inform targeted outbreak management and control.

Ongoing outbreak of Shigella flexneri serotype 3a in men who have sex with men in England and Wales, data from 2009-2011

Diagnoses of Shigella flexneri in the United Kingdom (UK) are usually travel-related. However, since 2009, there has been an overall increase in UK-acquired cases. The Health Protection Agency has been investigating a national outbreak of S. flexneri detected in 2011 and which is still ongoing. Cases occurred mostly in men who have sex with men and were of serotype 3a. The investigation aimed at obtaining epidemiological data to inform targeted outbreak management and control.

National outbreak of Salmonella Java phage type 3b variant 9 infection using parallel case-control and case-case study designs, United Kingdom, July to October 2010

Between July and October 2010, a national outbreak comprising 136 cases of Salmonella Java phage type 3b variant 9 was identified by the Health Protection Agency. Most cases were female. Cases had a median age of 39.5 years and lived in London, the South East and East of England. Parallel case–control and case–case study designs were undertaken to test the generated hypotheses. The case–case study aimed to examine if the infection was associated with eating food items purchased from commercial catering settings, and the reference group comprised non-travel related cases of S. Enteritidis infected during the same time period as the cases. The case–control study was designed to examine if the infection was associated with specific food items purchased from commercial catering settings, and recruited case-nominated controls. However, in response to poor recruitment we adapted our methods to investigate food exposures in the same way. Results of epidemiological investigations are compatible with salad vegetables as the potential source, but no common suppliers of salad were identified and no organisms were isolated from environmental and food samples. Limitations in the case–control study highlight the potential value of using a combination of epidemiological methods to investigate outbreaks.

National outbreak of Salmonella Java phage type 3b variant 9 infection using parallel case–control and case–case study designs, United Kingdom, July to October 2010

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