Comparing activity, toxicity and model membrane interactions of Jelleine-I and Trp/Arg analogs: analysis of peptide aggregation.

Increasing resistance in antibiotic and chemotherapeutic treatments has been pushing studies of design and evaluation of bioactive peptides. Designing relies on different approaches from minimalist sequences and endogenous peptides modifications to computational libraries. Evaluation relies on microbiological tests. Aiming a deeper understanding, we chose the octapeptide Jelleine-I (JI) for its selective and low toxicity profile, designed small modifications combining the substitutions of Phe by Trp and Lys/His by Arg and tested the antimicrobial and anticancer activity on melanoma cells. Biophysical methods identified environment-dependent modulation of aggregation, but critical aggregation concentrations of JI and analogs in buffer show that peptides start membrane interactions as monomers. The presence of model membranes increases or reduces the partial aggregation of peptides. Compared to JI, analog JIF2WR shows the lowest tendency to aggregation on bacterial model membranes. JI and analogs are lytic to model membranes. Their composition-dependent performance indicates preference for the higher charged anionic bilayers in line with their superior performance toward Staphylococcus aureus and Streptococcus pneumoniae. JIF2WR presented the higher partitioning, higher lytic activity and lower aggregated contents. Despite these increased membranolytic activities, JIF2WR exhibited comparable antimicrobial activity in relation to JI at the expenses of some loss in selectivity. We found that the substitution Phe/Trp (JIF2W) tends to decrease antimicrobial but to increase anticancer activity and aggregation on model membranes and the toxicity toward human cells. However, the concomitant substitution Lys/His by Arg (JIF2WR) modulates some of these tendencies, increasing both the antimicrobial and the anticancer activity while decreasing the aggregation tendency.

Evaluation of disinfection of surfaces at an outpatient unit before and after an intervention program.

BACKGROUND: Cleaning and disinfection processes must be improved so that there is a reduction in environmental contamination of frequent-contact surfaces. The objective of this study was to evaluate cleaning and disinfection of surfaces at a specialized healthcare unit after an intervention program. METHODS: Exploratory, longitudinal, and correlational study carried out in a medium-complexity clinic. Two hundred and forty samples from five surfaces were collected during three phases: diagnosis; implementation of an intervention program; and evaluation of immediate and long-term effects. In total, 720 evaluations were made, performed through three monitoring methods: visual inspection; adenosine triphosphate bioluminescence assay (ATP); and aerobic colony count (ACC). The Wilcoxon, Mann-Whitney, and Fisher's Exact tests were run to analyze data statistically. RESULTS: Cleaning and disinfection of surfaces were not being performed properly in most cases. Failure rates of surfaces reached 37.5 and 100% when the ATP and ACC procedures were used, respectively. However, after an intervention program, an improvement occurred. Success rates increased by 43.96% (ATP) and 12.46% (ACC) in phase I, by 70.6% (ATP) and 82.3% (ACC) immediately after interventions, and by 76.52% (ATP) and 85.76% (ACC) two months after the changes, showing that the program was effective. CONCLUSION: The present study reveals that implementing intervention actions with a cleaning and healthcare team brings benefits to prevent the spread of pathogenic agents through frequently touched hospital surfaces.

Effectiveness of ATP bioluminescence assay for presumptive identification of microorganisms in hospital water sources.

BACKGROUND: Laboratory analysis of organisms in water include arduous methods, such as the multiple tube and membrane filter. The ATP bioluminescence system, proposes a new way of measuring cellular material in water by measuring adenosine triphosphate (ATP) levels, which are expressed in relative light units (RLU). The ATP bioluminescence assay has been increasingly used to assess the microbiological safety of the hospital environment. However, there are few studies investigating the use of this methodology to evaluate the microbiological quality of water. The objective of the present study was to verify whether ATP, as measured by the 3 M™ Clean-Trace Water™ ATP test, can be used as an alternative tool for presumptive testing for the presence of microorganisms in hospital water. METHODS: Water samples (N = 88) were collected from faucets (74) and water purifiers (14) in a university hospital. The sample were filtered by the membrane filter technique (100 mL for bacterial analysis and 100 mL for fungal analysis) and then submitted to ATP bioluminescence assay to the determine quantity of RLU in each sample. In order to compare RLU and the presence of microorganisms, a receiver operating characteristic (ROC) curve was used to calculate sensitivity and specificity (levels higher than 90% were considered significant). In addition, control tests were conducted to compare RLU to the quantities of bacterial and fungal organisms added to distilled water (ANOVA and Tukey's tests; p ≤ 0.05). This inoculum was compared to RLU emission, and the data were analyzed by calculating the Pearson's correlation coefficient, with a 95% confidence interval. RESULTS: In the present study, 94.3% of the water samples presented bacterial growth. Of these, 15.6% showed heterotrophic bacteria above recommended levels and fungal contamination was detected in 55.6% of samples. Sensitivity and specificity of the samples were not significant (< 90%), and the correlation between ATP and the presence of these microorganisms in the samples (hospital water) was not significant, whereas, in distilled water, the results revealed a significant difference (p < 0.0001). CONCLUSIONS: These results demonstrated that the ATP test cannot be used as an alternative tool for presumptive assessment of the presence of microorganisms in water.

Essential Oil of Cymbopogon nardus (L.) Rendle: A Strategy to Combat Fungal Infections Caused by Candida Species.

BACKGROUND: The incidence of fungal infections, especially those caused by Candida yeasts, has increased over the last two decades. However, the indicated therapy for fungal control has limitations. Hence, medicinal plants have emerged as an alternative in the search for new antifungal agents as they present compounds, such as essential oils, with important biological effects. Published data demonstrate important pharmacological properties of the essential oil of Cymbopogon nardus (L.) Rendle; these include anti-tumor, anti-nociceptive, and antibacterial activities, and so an investigation of this compound against pathogenic fungi is interesting. OBJECTIVE: The aim of this study was to evaluate the chemical composition and biological potential of essential oil (EO) obtained from the leaves of C. nardus focusing on its antifungal profile against Candida species. METHODS: The EO was obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS). Testing of the antifungal potential against standard and clinical strains was performed by determining the minimal inhibitory concentration (MIC), time-kill, inhibition of Candida albicans hyphae growth, and inhibition of mature biofilms. Additionally, the cytotoxicity was investigated by the IC50 against HepG-2 (hepatic) and MRC-5 (fibroblast) cell lines. RESULTS: According to the chemical analysis, the main compounds of the EO were the oxygen-containing monoterpenes: citronellal, geranial, geraniol, citronellol, and neral. The results showed important antifungal potential for all strains tested with MIC values ranging from 250 to 1000 µg/mL, except for two clinical isolates of C. tropicalis (MIC > 1000 µg/mL). The time-kill assay showed that the EO inhibited the growth of the yeast and inhibited hyphal formation of C. albicans strains at concentrations ranging from 15.8 to 1000 µg/mL. Inhibition of mature biofilms of strains of C. albicans, C. krusei and C. parapsilosis occurred at a concentration of 10× MIC. The values of the IC50 for the EO were 96.6 µg/mL (HepG-2) and 33.1 µg/mL (MRC-5). CONCLUSION: As a major virulence mechanism is attributed to these types of infections, the EO is a promising compound to inhibit Candida species, especially considering its action against biofilm.

Assessment of disinfection of hospital surfaces using different monitoring methods.

OBJECTIVE: to assess the efficiency of cleaning/disinfection of surfaces of an Intensive Care Unit. METHOD: descriptive-exploratory study with quantitative approach conducted over the course of four weeks. Visual inspection, bioluminescence adenosine triphosphate and microbiological indicators were used to indicate cleanliness/disinfection. Five surfaces (bed rails, bedside tables, infusion pumps, nurses' counter, and medical prescription table) were assessed before and after the use of rubbing alcohol at 70% (w/v), totaling 160 samples for each method. Non-parametric tests were used considering statistically significant differences at p<0.05. RESULTS: after the cleaning/disinfection process, 87.5, 79.4 and 87.5% of the surfaces were considered clean using the visual inspection, bioluminescence adenosine triphosphate and microbiological analyses, respectively. A statistically significant decrease was observed in the disapproval rates after the cleaning process considering the three assessment methods; the visual inspection was the least reliable. CONCLUSION: the cleaning/disinfection method was efficient in reducing microbial load and organic matter of surfaces, however, these findings require further study to clarify aspects related to the efficiency of friction, its frequency, and whether or not there is association with other inputs to achieve improved results of the cleaning/disinfection process.

Efficacy of amphotericin B in a fat emulsion for the treatment of cryptococcal meningitis in AIDS patients.

Several formulae have been developed in an attempt to reduce the toxicity of amphotericin B (AmB), but their high costs preclude widespread use. The aim of this study was to evaluate the efficacy of amphotericin B in a fat emulsion, i.e. Intralipid (AmB-IL), in 37 AIDS patients with cryptococcal meningitis (CM). We retrospectively reviewed data collected in a non-comparative open study between January 1999 and December 2001. The therapeutic cure was defined as complete resolution or improvement of the clinical symptoms or complete absence or improvement of the mycological alterations of the CSF. The outcomes were evaluated at 2 weeks, induction phase (IP), and at the end of treatment or consolidation phase (CP) with the last available CSF. Prior to the diagnosis of CM, 72% of patients had had one or more OI and 67.57% had a concomitant OI. The median CD4-cell count was 32 cells/mm(3), the median leukocyte count in the CSF was 29 cells/mm(3) and the median cumulative dose of AmB-IL was 1,200 mg (300-2,500). The therapeutic cure was 57.14% in the IP and 64.86% in the CP. During IP, 9 patients died (24.32%) and 4 (10.81%) during the CP (p=0.2). Thus, the overall mortality rate was 35.14%. AmB-IL, an inexpensive preparation, might be an alternative to conventional AmB. Some questions remain such as its compatibility, stability and level of toxicity. The benefit is especially important in developing countries, where no drugs other than AmB are available to treat systemic fungal infections.