Objectives This study aimed to evaluate the antibiofilm activity and toxicity of the glycolic extract of Persea americana “P. americana” over multidrug-resistant strains of Acinetobacter baumannii “A. baumannii” as alternative therapy to be investigated. Methods A bacterial inoculum of each bacterial strain (4a, 5a, 9a, 12a, ATCC 19606) of A. baumannii was prepared and adjusted by the spectrophotometer. The microdilution broth method was performed to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). P. americana glycolic extracts were obtained of the tree stalk and leaves. The biofilm viability was tested by MTT assay after 5 min exposure. The toxicity of the extracts was tested by invertebrate model Galleria mellonella. The data were analyzed by ANOVA, Tukey test and log-rank method (α=0.05). Results The extract showed an inhibitory and bactericidal action over all the tested strains with the lowest MIC value observed for the reference strain (3.12 mg/mL). The extract did not demonstrate toxicity in any of the tested concentrations (12.5, 25 and 50 mg/mL) in Galleria mellonella larvae, with a survival percentage above 80% after 168 h. Conclusions The glycolic extract of P. americana has microbicidal and antibiofilm activity on multidrug-resistant clinical strains of A. baumannii and showed low toxicity for the invertebrate model G. mellonella.

The aim of this study was to isolate Enterobacteria and Pseudomonas from the oral cavity of hospitalized newborns (NB) and determine their prevalence and the sensitivity profile to most commonly used antibiotics for this age group. Samples from the oral cavity of NB from 24 to 48 h age were collected using swabs. The samples were inoculated on MacConkey agar, incubated and the colonies counted and identified. For each strain, the minimum inhibitory concentration (MIC) was determined using agar dilution test. Tests for enterobacteria producing extended spectrumβ-lactamases (ESBL) were performed using agar diffusion. Descriptive statistics was used for data analysis. Two of the isolated strains were submitted to the susceptibility test in biofilm. Of the collected samples, 8% presented Enterobacteria (mean of 6,141 CFU/mL) and no Pseudomona species was isolated. Positive samples were from NB in accommodation set or in the NB nursery. Enterobacter was the most prevalent genus and some strains were resistant to ampicillin, gentamicin and cephalothin. No ESBL strain was detected. Microorganisms in biofilms were resistant to all antibiotics, with concentrations four times higher than MIC. The presence of enterobacteria in the oral cavity of newborns, especially some strains resistant to normally used antibiotics, warns to the need for care to avoid the early colonization of this niche and the occurrence of a possible hospital infection in this age group.P r e v a l e n c e a n d S e n s i t i v i t y o f B a c i l l i a n d P s e u d o m o n a s i n t h e N e w b o r n ' s O r a l C a v i t y

Objective: The use of medicinal plants may be an alternative method for the control of Candida spp. responsible for human infections. This study evaluated the antifungal effect of Schinus terebinthifolius extract (Brazilian Peppertree) on C. albicans, C. dubliniensis, C. glabrata, and C. krusei planktonic cultures and biofilms. Material and Methods: Minimum inhibitory concentration (MIC) and minimum fungal concentration (MFC) of the plant extract were determined by the broth microdilution method. Biofilms formed in microplate wells were exposed to the extract for 5 min (50, 100 and 200 mg/mL) or 24 h (25, 50 and 100 mg/mL). After determination of colony-forming units per milliliter (CFU/mL), the data were analyzed by one-way ANOVA and Tukey’s Test (P ? 0.05). Results: Different MIC (mg/mL) were found, such as 0.39 (C. dubliniensis), 1.56 (C. albicans), and 3.13 (C. glabrata and C. krusei). Besides, MFC (mg/mL) of 0.78 (C. dubliniensis) and 3.13 (C. albicans, C. glabrata and C. krusei) were also observed. Regarding the biofilms, significant reductions (log10) were found after 5 min and 24 h exposure to the plant extract, compared to the control group. However, C. dubliniensis was significantly affected only in 24 h treatment. Conclusion: S. terebinthifolius extract presented a significant antifungal effect on C. albicans, C. dubliniensis, C. glabrata, and C. Krusei both in planktonic cultures and biofilms.

Objective: This research study aimed at evaluating the inhibitory activity of Matricaria recutira (chamomile) hydroalcoholic extract on Candida albicans and Enterobacter cloacae biofilms. Methods: C. albicans and E. cloacae biofilms with thirty-hour formation were submitted, for five minutes, to 100, 200 and 300 mg / mL of M. recutita hydroalcoholic extract, chlorhexidine digluconate 0.12% (Periogard® - inhibition control) or sterile distilled water (growth control). Subsequently, they were washed and divided into two groups to determine the microbial viability: G/UFC - counting of colony forming units (cfu) in agar and G/DNA - quantification of viable DNA with violet crystal dye by spectrophotometry. Results: M. recutita extract at 300 mg/mL reduced significantly (p <0.01) the E. cloacae cfu/mL number in biofilm with results similar to chlorhexidine 0.12%, while extracts at 100 and 200 mg/mL did not have the same effectiveness. The amount of E. cloacae viable DNA was reduced (p <0.05) in all the M. recutita extract concentrations and chlorhexidine. There was no significant difference (p = 0.565) in the cfu/mL number or in the amount of viable DNA (p = 0.8094) in C. albicans biofilm when compared to untreated biofilm (control) or, even, between the extracts when compared to each other or to chlorhexidine 0.12%. Conclusion: 300 mg/mL M. recutita extract reduced significantly the E. cloacae biofilm but not the C. albicans, both with a similar result to chlorhexidine 0.12% (Periogar®).

Stryphnodendron adstringens (Mart.) Coville is a medicinal plant known for its anti-inflammatory and antimicrobial properties. This study evaluated some biological activities of extract from S. adstringens. Antimicrobial activity was checked in planktonic cultures and monomicrobial biofilms on aerobic, and anaerobic dental microorganisms. Analyzes of cytotoxicity using MTT assay, and genotoxicity by micronucleus test were performed in human keratinocytes (HACAT), murine macrophages (RAW 264.7), and murine fibroblasts (L929). The anti-inflammatory effect was checked in RAW 264.7 stimulated by lipopolysaccharide (LPS) from Escherichia coli, and treated with the plant extract. The levels of cytokines, and nitric oxide (NO) were measured by ELISA, and Griess method, respectively. Data were analyzed by ANOVA, followed by Tukey's, or Kruskal-Wallis, and Dunns tests (P ≤ 0.05). Biofilms of anaerobic bacteria were very susceptible to the plant extract. Effective concentrations showed cell viability > 50%, except 25 mg/mL for HACAT after 24 h of exposure. The extract of S. adstringens was not genotoxic for RAW 264.7. LPS associated with extract increased the production of all cytokines, except TNF-α. However, the plant extract decreased the production of NO. In conclusion, the extract of S. adstringens affected biofilm of anaerobic bacteria using non-cytotoxic concentrations for RAW 264.7, L929, and HACAT cells.

One of the factors that make the treatment of Enterococcus faecalis infections difficult is their ability to form biofilm, as well as their natural and acquired resistance to antibiotics which does not have specific drugs for their inhibition. This fact makes essential the search for alternative treatments, as the use of probiotics strains of Lactobacillus rhamnosus has been effective in the treatment of some diseases. In this investigation, the relationship between the probiotic strain of L. rhamnosus and E. faecalis during the biofilm formation was analyzed. Standardized suspensions used in biofilm development and treatment in different stages of the biofilm formation were prepared. The L. rhamnosus suspension was placed in contact for 90 min with E. faecalis freshly created biofilms (initial adherence) in the 24 h biofilms. The same was made with E. faecalis suspension on L. rhamnosus biofilms. L. rhamnosus showed no inhibitory effects on E. faecalis biofilms formation, with an increase in the counting of colony forming units in the treated groups (p=0.0047, p=0.0060). About the L. rhamnosus biofilms, there was no significant difference for both treatment stages. The probiotic strain interfered in vitro with the E. faecalis biofilm formation, thereby intensifying the growth of E. faecalis biofilm.