In vitro antistaphylococcal effects of a novel 45S5 bioglass/agar-gelatin biocomposite films.

AIMS: To assess the antibacterial efficacy of new composite materials developed from microparticles of 45S5 bioactive glass (BG) and agar-gelatin films. METHODS AND RESULTS: In vitro antibacterial activity was evaluated against Staphylococcus spp. because of the importance of this pathogen in damaged tissues and in failures associated with biomaterial implants. To our knowledge, this is the first paper reporting on the suitable combination of BG and agar-gelatin for bioactive and antibacterial films. Bacterial suspensions up or below 10(5) CFU ml(-1) reflecting situations of wound infection and of noninfection, respectively, were prepared and then put in contact with the biomaterials at 37°C. After 24 and 48 h of incubation, the pH value was measured and the staphylococci strains viability was determined by counting in Mueller-Hinton agar plates. Moreover, the biomaterials were prepared for observation under scanning electron microscopy (SEM). Biocomposites (BCs) showed a strong antibacterial effect against all staphylococci strains tested. Some differences were found depending on the strain, the inoculum size and the contact time. This effect was correlated with an alkalinization of the media. By SEM analyses, no bacterial presence was observed on the surface of BCs in any of the cell concentrations tested at any time. CONCLUSIONS: Overall, the coating of 45S5 BG on agar-gelatin films promoted BCs with strong antistaphylococcal activity. The effect was efficient under bacterial concentration up or below 10(5) CFU ml(-1). Additionally, none of the strains were found on BCs surfaces. SIGNIFICANCE AND IMPACT OF STUDY: 45S5 bioglass/agar-gelatin biocomposite films are reported for the first time. The results suggest a potential application as wound dressing.

Properties of different lactic acid bacteria isolated from Apis mellifera L. bee-gut.

Eight strains belonging to Lactobacillus spp. and five to Enterococcus spp. were isolated from the gut of worker Apis mellifera L. bees. Studies based on 16S rRNA sequencing revealed that AJ5, IG9, A15 and CRL1647 strains had a 99% identity with Lactobacillus johnsonii, while SM21 showed a 99% similarity with Enterococcus faecium. L. johnsonii CRL1647, AJ5 and IG9 were high lactic acid producers (values were between 177 and 275 mM), and in vitro they inhibited different human food-borne pathogens and Paenibacillus larvae, the American foulbrood agent. This bacterium was the most sensitive to the lactic acid effect being inhibited by 44 mM of this metabolite. L. johnsonii CRL1647, AJ5 and IG9 also presented important surface properties. These cells showed between 77% and 93% of auto-aggregation. The preliminary study of the chemical nature of the aggregating factors revealed that the molecules involved in the surface of each L. johnsonii strain were quite complex; and something of a peptidic nature was mainly involved. E. faecium SM21 produced bacteriocin-like compounds with anti-Listeria effects. Furthermore, a band close to 6.0-7.5 kDA was detected by SDS-PAGE studies, and the entA, B and P structural genes were amplified by PCR reactions. For the first time, bee-gut associated L. johnsonii and E. faecium strains have been isolated, identified, cultivated and some of their functional properties reported.

Protective effect of Enterococcus faecium J96, a potential probiotic strain, on chicks infected with Salmonella Pullorum.

Enterococcus faecium J96 was isolated from a healthy free-range chicken and it inhibited Salmonella Pullorum, in vitro, due to its lactic acid and bacteriocin production. In vivo assays were carried out with 30-h-old broiler chicks. The lactic acid bacteria (approximately 1 x 10(9) cells per chick) were orally administered as preventive and as therapeutic treatments. In the first case they were given to the chicks twice a day for 3 consecutive days. In the second case the lactic bacteria were administered in the same way after a 24-h challenge by Salmonella Pullorum (in both instances the salmonella dose was 1 x 10(5) cells per chick). Cecal contents, liver, and spleens were analyzed and liver and spleen fragments were also fixed in formaldehyde (pH 7.00) in order to determine salmonella translocation. The chickens that were preventively treated with E. faecium J96 survived the Salmonella Pullorum challenge. Those that were infected on the first day and then inoculated with lactic bacteria died 4 days later. Salmonellae were isolated from their livers and spleens. From these results we may conclude that E. faecium J96 can protect newly hatched chicks from Salmonella Pullorum infection but cannot act as a good therapeutic agent.