Bacterial Symbionts in Ceratitis capitata

Ceratitis capitata (Diptera: Tephritidae) is responsible for extensive damage in agriculture with important economic losses. Several strategies have been proposed to control this insect pest including insecticides and the Sterile Insect Technique. Traditional control methods should be implemented by innovative tools, among which those based on insect symbionts seem very promising. Our study aimed to investigate, through the 16S Miseq analysis, the microbial communities associated with selected organs in three different medfly populations to identify possible candidates to develop symbiont-based control approaches. Our results confirm that Klebsiella and Providencia are the dominant bacteria in guts, while a more diversified microbial community has been detected in reproductive organs. Concertedly, we revealed for the first time the presence of Chroococcidiopsis and Propionibacterium as stable components of the medfly’s microbiota. Additionally, in the reproductive organs, we detected Asaia, a bacterium already proposed as a tool in the Symbiotic Control of Vector-Borne Diseases. A strain of Asaia, genetically modified to produce a green fluorescent protein, was used to ascertain the ability of Asaia to colonize specific organs of C. capitata. Our study lays the foundation for the development of control methods for C. capitata based on the use of symbiont bacteria.

Draft genome of an extremely drug-resistant st551 Staphylococcus pseudintermedius from an Italian dog with otitis externa

OBJECTIVES

To determine the draft genome sequence and analyse the genetic features of a Staphylococcus pseudintermedius clinical isolate according to the main typing schemes available, with a special focus on antibiotic resistance.

METHODS

The strain was isolated from a case of otitis externa in a dog. Its identity and pattern of antibiotic susceptibility were determined using an automated system. The genome was sequenced using an Illumina platform. MLST, SCCmec typing, resistome, and mobile genetic elements were derived by comparative analysis using available specific databases.

RESULTS

S. pseudintermedius CAM1 isolate has a chromosome size of 2 652 610 bp. It showed a wide pattern of phenotypic resistance, comprising beta-lactams, macrolides and lincosamides, aminoglycosides, fluoroquinolones, tetracyclines, and trimethoprim-sulfamethoxazole. The genetic determinants of the underlying mechanisms were all found by in silico analysis of the genome. The mecA gene for methicillin resistance was harboured by the Vc type of the SCCmec. MLST of the strain was st551.

CONCLUSION

By comparison with the MLST database of S. pseudintermedius and data from published molecular epidemiology studies, CAM1 is the first st551 strain recorded in Italy and, in the context of an already extremely wide antibiotic resistance pattern, it harbours also the tetK gene, the prevalence of which is rare in MDR S. pseudintermedius.

Testing Surgical Face Masks in an Emergency Context: The Experience of Italian Laboratories during the COVID-19 Pandemic Crisis

The first wave of the COVID-19 pandemic brought about a broader use of masks by both professionals and the general population. This resulted in a severe worldwide shortage of devices and the need to increase import and activate production of safe and effective surgical masks at the national level. In order to support the demand for testing surgical masks in the Italian context, Universities provided their contribution by setting up laboratories for testing mask performance before releasing products into the national market. This paper reports the effort of seven Italian university laboratories who set up facilities for testing face masks during the emergency period of the COVID-19 pandemic. Measurement set-ups were built, adapting the methods specified in the EN 14683:2019+AC. Data on differential pressure (DP) and bacterial filtration efficiency (BFE) of 120 masks, including different materials and designs, were collected over three months. More than 60% of the masks satisfied requirements for DP and BFE set by the standard. Masks made of nonwoven polypropylene with at least three layers (spunbonded-meltblown-spunbonded) showed the best results, ensuring both good breathability and high filtration efficiency. The majority of the masks created with alternative materials and designs did not comply with both standard requirements, resulting in suitability only as community masks. The effective partnering between universities and industries to meet a public need in an emergency context represented a fruitful example of the so-called university "third-mission".

Structure/activity virtual screening and in vitro testing of small molecule inhibitors of 8-hydroxy-5-deazaflavin:NADPH oxidoreductase from gut methanogenic bacteria

Virtual screening techniques and in vitro binding/inhibitory assays were used to search within a set of more than 8,000 naturally occurring small ligands for candidate inhibitors of 8-hydroxy-5-deazaflavin:NADPH oxidoreductase (FNO) from Methanobrevibacter smithii, the enzyme that catalyses the bidirectional electron transfer between NADP⁺ and F420H₂ during the intestinal production of CH₄ from CO₂. In silico screening using molecular docking classified the ligand-enzyme complexes in the range between - 4.9 and - 10.5 kcal/mol. Molecular flexibility, the number of H-bond acceptors and donors, the extent of hydrophobic interactions, and the exposure to the solvent were the major discriminants in determining the affinity of the ligands for FNO. In vitro studies on a group of these ligands selected from the most populated/representative clusters provided quantitative kinetic, equilibrium, and structural information on ligands' behaviour, in optimal agreement with the predictive computational results.

Exploring new applications of tulip tree (Liriodendron tulipifera L.): leaf essential oil as apoptotic agent for human glioblastoma

Liriodendron tulipifera L. (Magnoliaceae), also known as "tulip tree," is a hardwood plant native to North America, cultivated all over the world and used on an industrial level, especially for its fine wood and to make honey. It has also been traditionally exploited for its antimalarial properties. However, our knowledge about the bioactivity of its essential oil remains patchy. In this research, we focused on the biological evaluation of the volatile fractions obtained from different parts of the plant which are normally discharged by industry, including leaves, flowers, and fruits. For the purpose, the essential oils were obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS). Then, they were evaluated as radical scavenging, antioxidant, antimicrobial, and antiproliferative agents by using DPPH, ABTS, FRAP, disk diffusion, and MTT methods, respectively. The significant toxicity exhibited on human tumor cells, namely A375 malignant melanoma, HCT116 colon carcinoma, MDA-MB 231 breast adenocarcinoma, and T98G glioblastoma multiforme cell lines, prompted us to study the mechanism of action by acridine orange/ethidium bromide double staining and caspase 3 assays. Our findings shed light on the potential applications of tulip tree derivatives as anticancer drugs.

Quaternary Ammonium Leucine-Based Surfactants: The Effect of a Benzyl Group on Physicochemical Properties and Antimicrobial Activity

Quaternary ammonium amphiphiles are a class of compounds with a wide range of commercial and industrial uses. In the pharmaceutical field, the most common quaternary ammonium surfactant is benzalkonium chloride (BAC), which is employed as a preservative in several topical formulations for ocular, skin, or nasal application. Despite the broad antimicrobial activity against Gram-positive and Gram-negative bacteria, as well as fungi and small enveloped viruses, safety concerns regarding its irritant and cytotoxic effect on epithelial cells still remain. In this work, quaternary ammonium derivatives of leucine esters (C10, C12 and C14) were synthesised as BAC analogues. These cationic surfactants were characterised in terms of critical micelle concentration (CMC, by tensiometry), cytotoxicity (MTS and LDH assays on the Caco-2 and Calu-3 cell lines) and antimicrobial activity on the bacterial species Staphylococcus aureus and Enterococcus faecalis among the Gram-positives, Escherichia coli and Pseudomonas aeruginosa among the Gram-negatives and the yeast Candida albicans. They showed satisfactory surface-active properties, and a cytotoxic effect that was dependent on the length of the hydrophobic chain. Lower minimum inhibiting concentration (MIC) values were calculated for C14-derivatives, which were comparable to those calculated for BAC toward Gram-positive bacteria and slightly higher for Gram-negative bacteria and C. albicans. Thus, the synthesised leucine-based quaternary ammonium cationic surfactants can potentially find application as promising surface-active compounds with antimicrobial activity.

A New Species of the γ-Proteobacterium Francisella, F. adeliensis Sp. Nov., Endocytobiont in an Antarctic Marine Ciliate and Potential Evolutionary Forerunner of Pathogenic Species

The study of the draft genome of an Antarctic marine ciliate, Euplotes petzi, revealed foreign sequences of bacterial origin belonging to the γ-proteobacterium Francisella that includes pathogenic and environmental species. TEM and FISH analyses confirmed the presence of a Francisella endocytobiont in E. petzi. This endocytobiont was isolated and found to be a new species, named F. adeliensis sp. nov.. F. adeliensis grows well at wide ranges of temperature, salinity, and carbon dioxide concentrations implying that it may colonize new organisms living in deeply diversified habitats. The F. adeliensis genome includes the igl and pdp gene sets (pdpC and pdpE excepted) of the Francisella pathogenicity island needed for intracellular growth. Consistently with an F. adeliensis ancient symbiotic lifestyle, it also contains a single insertion-sequence element. Instead, it lacks genes for the biosynthesis of essential amino acids such as cysteine, lysine, methionine, and tyrosine. In a genome-based phylogenetic tree, F. adeliensis forms a new early branching clade, basal to the evolution of pathogenic species. The correlations of this clade with the other clades raise doubts about a genuine free-living nature of the environmental Francisella species isolated from natural and man-made environments, and suggest to look at F. adeliensis as a pioneer in the Francisella colonization of eukaryotic organisms.

High virulence gene diversity in Streptococcus pyogenes isolated in Central Italy

Globally, Streptococcus pyogenes poses a continuous burden on human health, causing both self-limiting and life-threatening diseases. Therefore, studying the profile of virulence genes and their combinations is essential to monitor the epidemiology and pathogenic potential of this important species. Thus, the aim of this study was to analyze related genetic features of clinical strains collected in Italy in 2012 in order to obtain a valid picture of their virulence profile that could be compared to similar studies made in other countries approximately in the same period. We conducted emm typing and fibronectin-collagen-T antigen (FCT) region typing in 122 Streptococcus pyogenes strains. Furthermore, several additional virulence genes were screened by polymerase chain reaction. We found correlations between emm types and FCT region profiles. emm1 strains were mainly associated with FCT2 and FCT6, while emm89 and emm12 strains were associated with FCT4. FCT5 was mainly represented in emm4, emm6, and emm75 strains. Significantly, we defined subtypes for each FCT type based on the differences in single and double loci compared to the reference scheme used for the classification of the FCT region. In addition, new FCT-region variants with differences in multiple loci were also recorded. Cluster analysis based on virulence gene profiling showed a non-random distribution within each emm type. This study added new data to existing studies conducted worldwide and revealed new variability scores in circulating Streptococcus pyogenes strains and new assortments in well-established virulence gene signatures.

Bioactivity and Structural Properties of Novel Synthetic Analogues of the Protozoan Toxin Climacostol

Climacostol (5-[(2Z)-non-2-en-1-yl]benzene-1,3-diol) is a resorcinol produced by the protozoan Climacostomum virens for defence against predators. It exerts a potent antimicrobial activity against bacterial and fungal pathogens, inhibits the growth of several human and rodent tumour cells, and is now available by chemical synthesis. In this study, we chemically synthesized two novel analogues of climacostol, namely, 2-methyl-5 [(2Z)-non-2-en-1-yl]benzene-1,3-diol (AN1) and 5-[(2Z)-non-2-en-1-yl]benzene-1,2,3-triol (AN2), with the aim to increase the activity of the native toxin, evaluating their effects on prokaryotic and free-living protists and on mammalian tumour cells. The results demonstrated that the analogue bearing a methyl group (AN1) in the aromatic ring exhibited appreciably higher toxicity against pathogen microbes and protists than climacostol. On the other hand, the analogue bearing an additional hydroxyl group (AN2) in the aromatic ring revealed its ability to induce programmed cell death in protistan cells. Overall, the data collected demonstrate that the introduction of a methyl or a hydroxyl moiety to the aromatic ring of climacostol can effectively modulate its potency and its mechanism of action.

Phylogenetic relationships, biofilm formation, motility, antibiotic resistance and extended virulence genotypes among Escherichia coli strains from women with community-onset primitive acute pyelonephritis

The present work set out to search for a virulence repertoire distinctive for Escherichia coli causing primitive acute pyelonephritis (APN). To this end, the virulence potential of 18 E. coli APN strains was genotypically and phenotypically assessed, comparatively with 19 strains causing recurrent cystitis (RC), and 16 clinically not significant (control, CO) strains. Most of the strains belong to phylogenetic group B1 (69.8%; p<0.01), and APN strains showed unique features, which are the presence of phylogroup A, and the absence of phylogroup B2 and non-typeable strains. Overall, the most dominant virulence factor genes (VFGs) were ecpA and fyuA (92.4 and 86.7%, respectively; p<0.05), and the mean number of VFGs was significantly higher in uropathogenic strains. Particularly, papAH and malX were exclusive for uropathogenic strains. APN and RC strains showed a significantly higher prevalence of fyuA, usp, and malX than of CO strains. Compared to RC strains, APN ones showed a higher prevalence of iha, but a lower prevalence of iroN, cnf1, and kpsMT-II. Hierarchical cluster analysis showed a higher proportion of two gene clusters (malX and usp, and fyuA and ecpA) were detected in the APN and RC groups than in CO, whereas iutA and iha clusters were detected more frequently in APN strains. The motility level did not differ among the study-groups and phylogroups considered, although a higher proportion of swarming strains was observed in APN strains. Antibiotic-resistance rates were generally low except for ampicillin (37.7%), and were not associated with specific study- or phylogenetic groups. APN and RC strains produced more biofilm than CO strains. In APN strains, iha was associated with higher biofilm biomass formation, whereas iroN and KpSMT-K1 were associated with a lower amount of biofilm biomass. Further work is needed to grasp the virulence and fitness mechanisms adopted by E. coli causing APN, and hence develop new therapeutic and prophylactic approaches.

Microbiological evaluation of ready-to-eat iceberg lettuce during shelf-life and effectiveness of household washing methods

The aim of this study was to assess the microbiological quality of ready-to-eat (RTE) iceberg lettuce. Our investigation was based on the consumption tendency of university students considered a target market for this product. A total of 78 RTE samples were collected from chain supermarkets and analysed for the enumeration of aerobic mesophilic count (AMC), Escherichia coli and the detection of Salmonella spp. and Listeria monocytogenes. All samples were negative for the presence of pathogens. The mean value of AMC at the beginning, in the middle and after the expiration date was: 6.88, 8.51 and 8.72 log CFU g-1, respectively. The same investigation was performed on 12 samples of fresh iceberg lettuce samples. No pathogens were found and the mean value of AMC was lower than the RTE category (5.73 log CFU g-1; P<0.05). The effectiveness of 5 washing methods was determined on 15 samples of both fresh and RTE iceberg lettuce. Samples were washed for 15' and 30' in tap water (500 mL), tap water with NaCl (4 g/500 mL), tap water with bicarbonate (8 g/500 mL), tap water with vinegar (10 mL/500 mL) and tap water with chlorine-based disinfectant (10 mL/500 mL). A significant bacterial load reduction was recorded for vinegar and disinfectant after 30' and 15', respectively. Overall, these results showed that RTE iceberg lettuce is more contaminated than the fresh product. Also, the consumption in the first few days of packaging and after washing with disinfectants reduces the risk for health consumers.

Antidiabetic "gliptins" affect biofilm formation by Streptococcus mutans

Streptococcus mutans, a dental caries causing odontopathogen, produces X-prolyl dipeptidyl peptidase (Sm-XPDAP, encoded by pepX), a serine protease known to have a nutritional role. Considering the potential of proteases as therapeutic targets in pathogens, this study was primarily aimed at investigating the role of Sm-XPDAP in contributing to virulence-related traits. Dipeptidyl peptidase (DPP IV), an XPDAP analogous enzyme found in mammalian tissues,is a well known therapeutic target in Type II diabetes. Based on the hypothesis that gliptins, commonly used as anti-human-DPP IV drugs, may affect bacterial growth upon inhibition of Sm-XPDAP, we have determined their ex vivo antimicrobial and anti-biofilm activity towards S. mutans. All three DPP IV drugs tested reduced biofilm formation as determined by crystal violet staining. To link the observed biofilm inhibition to the human-DPP IV analogue present in S. mutans UA159, a pepX isogenic mutant was generated. In addition to reduced biofilm formation, CLSM studies of the biofilm formed by the pepX isogenic mutant showed these were comparable to those formed in the presence of saxagliptin, suggesting a probable role of this enzyme in biofilm formation by S. mutans UA159. The effects of both pepX deletion and DPP IV drugs on the proteome were studied using LC-MS/MS. Overall, this study highlights the potential of Sm-XPDAP as a novel anti-biofilm target and suggests a template molecule to synthesize lead compounds effective against this enzyme.

Genotypic and phenotypic heterogeneity in Streptococcus mutans isolated from diabetic patients in Rome, Italy

Our study focuses on the antimicrobial susceptibility, genotypic and phenotypic heterogeneity, and serotype classification of the Streptococcus mutans isolated from type II diabetic patients (n = 25; age 42-68). Eighty-two percent of isolates were classified as serotype c. No serotype k was present. Macrorestriction analysis of genomic DNA of the isolates exhibited a clonal diversity that paralleled the phenotypic heterogeneity, which was also assessed in terms of biofilm forming ability. Isolates were susceptible to all the classes of antibiotics. In conclusion a great heterogeneity and no antimicrobial resistance were apparent in the considered S. mutans strains from diabetic patients.

Biological Activities of the Essential Oil from Erigeron floribundus

Erigeron floribundus (Asteraceae) is an herbaceous plant widely used in Cameroonian traditional medicine to treat various diseases of microbial and non-microbial origin. In the present study, we evaluated the in vitro biological activities displayed by the essential oil obtained from the aerial parts of E. floribundus, namely the antioxidant, antimicrobial and antiproliferative activities. Moreover, we investigated the inhibitory effects of E. floribundus essential oil on nicotinate mononucleotide adenylyltransferase (NadD), a promising new target for developing novel antibiotics, and Trypanosoma brucei, the protozoan parasite responsible for Human African trypanosomiasis. The essential oil composition was dominated by spathulenol (12.2%), caryophyllene oxide (12.4%) and limonene (8.8%). The E. floribundus oil showed a good activity against Staphylococcus aureus (inhibition zone diameter, IZD of 14 mm, minimum inhibitory concentration, MIC of 512 µg/mL). Interestingly, it inhibited the NadD enzyme from S. aureus (IC₅₀ of 98 µg/mL), with no effects on mammalian orthologue enzymes. In addition, T. brucei proliferation was inhibited with IC₅₀ values of 33.5 µg/mL with the essential oil and 5.6 µg/mL with the active component limonene. The essential oil exhibited strong cytotoxicity on HCT 116 colon carcinoma cells with an IC₅₀ value of 14.89 µg/mL, and remarkable ferric reducing antioxidant power (tocopherol-equivalent antioxidant capacity, TEAC = 411.9 μmol·TE/g).

Bioactive Secondary Metabolites from Schizogyne sericea (Asteraceae) Endemic to Canary Islands

Schizogyne sericea (Asteraceae) is a halophytic shrub endemic to the Canary Islands and traditionally employed as analgesic, astringent, anti-inflammatory, and vulnerary. A comprehensive phytochemical investigation was conducted on the flowering aerial parts by analyzing both essential oil constituents and polar compounds. The essential oil was dominated by p-cymene, with the noteworthy occurrence of β-pinene and thymol esters. From the EtOH extract, eight compounds were isolated and structurally elucidated. Essential oil, polar fractions, and isolates (2), (4), and (5) were separately in vitro assayed for antiproliferative activity on human tumor cell lines (A375, MDA-MB 231, and HCT116) by MTT assay, for antioxidant potential by DPPH, ABTS, and FRAP assays, and for antimicrobial activity by the agar disk diffusion method. Results revealed that essential oil and compounds 1 and 2 exert a strong inhibition on tumor cells, and in some cases, higher than that of cisplatin. Fractions containing thymol derivatives (1 and 2) and caffeoylquinic acid derivatives 4 and 5 displayed antioxidant activity comparable to that of Trolox, making S. sericea extract an interesting natural product with potential applications as preservative or in the treatment of diseases in which oxidative stress plays an important role.

Molecular cloning and biochemical characterization of Xaa-Pro dipeptidyl-peptidase from Streptococcus mutans and its inhibition by anti-human DPP IV drugs

Streptococcus mutans harbours an intracellular, human DPP IV-analogous enzyme Xaa-Pro dipeptidyl-peptidase (EC 3.4.14.11). According to previous reports, an extracellular isozyme in S. gordonii and S. suis has been associated with virulence. Speculating that even an intracellular form may aid in virulence of S. mutans, we have tried to purify, characterize and evaluate enzyme inhibition by specific inhibitors. The native enzyme was partially purified by ion-exchange and gel filtration chromatography. Owing to low yield, the enzyme was overexpressed in Lactococcus lactis and purified by affinity chromatography. The recombinant enzyme (rSm-XPDAP) had a specific activity of 1070 U mg(-1), while the Vmax and Km were 7 μM min(-1) and 89 ± 7 μM (n = 3), respectively. The serine protease inhibitor phenylmethylsulphonyl fluoride and a DPP IV-specific inhibitor diprotin A proved to be active against rSm-XPDAP. As a novel approach, the evaluation of the effect of anti-human DPP IV (AHD) drugs on rSm-XPDAP activity found saxagliptin to be effective to some extent (Ki = 129 ± 16 μM), which may lead to the synthesis and development of a new class of antimicrobial agents.

A yeast strain associated to Anopheles mosquitoes produces a toxin able to kill malaria parasites

Background

Malaria control strategies are focusing on new approaches, such as the symbiotic control, which consists in the use of microbial symbionts to prevent parasite development in the mosquito gut and to block the transmission of the infection to humans. Several microbes, bacteria and fungi, have been proposed for malaria or other mosquito-borne diseases control strategies. Among these, the yeast Wickerhamomyces anomalus has been recently isolated from the gut of Anopheles mosquitoes, where it releases a natural antimicrobial toxin. Interestingly, many environmental strains of W. anomalus exert a wide anti-bacterial/fungal activity and some of these ‘killer’ yeasts are already used in industrial applications as food and feed bio-preservation agents. Since a few studies showed that W. anomalus killer strains have antimicrobial effects also against protozoan parasites, the possible anti-plasmodial activity of the yeast was investigated.

Methods

A yeast killer toxin (KT), purified through combined chromatographic techniques from a W. anomalus strain isolated from the malaria vector Anopheles stephensi, was tested as an effector molecule to target the sporogonic stages of the rodent malaria parasite Plasmodium berghei, in vitro. Giemsa staining was used to detect morphological damages in zygotes/ookinetes after treatment with the KT. Furthermore, the possible mechanism of action of the KT was investigated pre-incubating the protein with castanospermine, an inhibitor of β-glucanase activity.

Results

A strong anti-plasmodial effect was observed when the P. berghei sporogonic stages were treated with KT, obtaining an inhibition percentage up to around 90 %. Microscopy analysis revealed several ookinete alterations at morphological and structural level, suggesting the direct implication of the KT-enzymatic activity. Moreover, evidences of the reduction of KT activity upon treatment with castanospermine propose a β-glucanase-mediated activity.

Conclusion

The results showed the in vitro killing efficacy of a protein produced by a mosquito strain of W. anomalus against malaria parasites. Further studies are required to test the KT activity against the sporogonic stages in vivo, nevertheless this work opens new perspectives for the possible use of killer strains in innovative strategies to impede the development of the malaria parasite in mosquito vectors by the means of microbial symbionts.

Electronic supplementary material

The online version of this article (doi:10.1186/s12936-015-1059-7) contains supplementary material, which is available to authorized users.

Blue honeysuckle fruit (Lonicera caerulea L.) from eastern Russia: phenolic composition, nutritional value and biological activities of its polar extracts

We conducted a chemical and biological investigation of blue honeysuckle growing in eastern Russia.

DNA and BSA binding, anticancer and antimicrobial properties of Co(ii), Co(ii/iii), Cu(ii) and Ag(i) complexes of arylhydrazones of barbituric acid

Novel arylhydrazones of barbituric acid were synthesized and their water soluble Ag^I, Co^II, Co^II/III and Cu^II complexes obtained. The Ag^I compound shows remarkable cytotoxic and antibacterial activity.

Correlation between genetic features of the mef(A)-msr(D) locus and erythromycin resistance in Streptococcus pyogenes

We investigated the correlation between the genetic variation within mef(A)-msr(D) determinants of efflux-mediated erythromycin resistance in Streptococcus pyogenes and the level of erythromycin resistance. Twenty-eight mef(A)-positive strains were selected according to erythromycin MIC (4-32 μg/mL), and their mef(A)-msr(D) regions were sequenced. Strains were classified according to the bacteriophage carrying mef(A)-msr(D). A new Φm46.1 genetic variant was found in 8 strains out of 28 and named VP_00501.1. Degree of allelic variation was higher in mef(A) than in msr(D). Hotspots for recombination were mapped within the locus that could have shaped the apparent mosaic structure of the region. There was a general correlation between mef(A)-msr(D) sequence and erythromycin resistance level. However, lysogenic conversion of susceptible strains by mef(A)-msr(D)-carrying Φm46.1 indicated that key determinants may not all reside within the mef(A)-msr(D) locus and that horizontal gene transfer could contribute to changes in the level of antibiotic resistance in S. pyogenes.

Decline in macrolide resistance rates among Streptococcus pyogenes causing pharyngitis in children isolated in Italy

Macrolides are often used to treat group A streptococcus (GAS) infections, but their resistance rates reached high proportions worldwide. The aim of the present study was to give an update on the characteristics and contemporary prevalence of macrolide-resistant pharyngeal GAS in Central Italy. A total of 592 isolates causing pharyngitis in children were collected in the period 2012–2013. Clonality was assessed by emm typing and pulsed-field gel electrophoresis (PFGE) for all macrolide-resistant strains and for selected susceptible isolates. Genetic determinants of resistance were screened by polymerase chain reaction (PCR). Forty-four GAS were erythromycin-resistant (7.4 %). Among them, 52.3 % and 50 % were clindamycin- and tetracycline-resistant, respectively. erm(B)-positive isolates (52.3 %) expressed the constitutive cMLS_B phenotype. mef(A) and its associated M phenotype were recorded in 40.9 % of the cases. The remaining erm(A)-positive isolates expressed the iMLS_B phenotype. Seventeen tetracycline-resistant isolates carried tet(M) and five isolates carried tet(O). Twenty-five emm types were found among all strains, with the predominance of emm types 12, 89, 1, and 4. Eleven emm types and 12 PFGE clusters characterized macrolide-resistant strains, with almost two-thirds belonging to emm12, emm4, and emm11. Macrolide-susceptible and -resistant emm types 12, 89, 11, and 4 shared related PFGE profiles. There was a dramatic decline in macrolide resistance in Central Italy among pharyngeal GAS isolates in 2012–2013 when compared to previous studies from the same region (p < 0.05), although macrolide consumption remained stable over the past 15 years. We observed a decrease in the proportion of macrolide-resistant strains within emm types commonly associated with macrolide resistance in the past, namely emm12, 1, and 89.

Pulsed field gel electrophoresis of group A streptococci

Here we describe the protocols to perform PFGE analysis of chromosomal DNA from the bacterial species Streptococcus pyogenes (group A streptococcus, GAS) after digestion with the restriction enzyme SmaI. Large parts of the procedures are suitable for application to DNA digested with other restriction enzymes as well. We have put an effort to present extensions to solve possible limitations to the discriminatory power of the method in the specific case of S. pyogenes.

Syntheses, structures, and antimicrobial activity of new remarkably light-stable and water-soluble tris(pyrazolyl)methanesulfonate silver(I) derivatives of N-methyl-1,3,5-triaza-7-phosphaadamantane salt - [mPTA]BF4

Two new silver(I) complexes of formula [Ag(mPTA)4](Tpms)4(BF4) (1) and [Ag(Tpms)(mPTA)](BF4) (2) (mPTA = N-methyl-1,3,5-triaza-7-phosphaadamantane cation, Tpms = tris(pyrazol-1-yl)methanesulfonate anion) have been synthesized and fully characterized by elemental analyses, (1)H and (31)P{(1)H} NMR, ESI-MS, and IR spectroscopic techniques. The single-crystal X-ray diffraction study of 1 discloses a noncoordinated nature of the Tpms species, existing as counterions around the highly charged metal center [Ag(mPTA)](5+), 1 being the first reported coordination compound bearing a κ(0)-Tpms. 1 features high solubility and stability in water (S25 °C ≈ 30 mg·mL(-1)). The two complexes interact with calf thymus DNA via intercalation mode, binding to the BSA with decrease of its tryptophan fluorescence with a static quenching mechanism. The two new silver complexes exhibit significant antibacterial and antifungal activities screened in vitro against the standard strains of Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa, Escherichia coli, and Candida albicans.

Phytochemical analysis and in vitro biological activity of three Hypericum species from the Canary Islands (Hypericum reflexum, Hypericum canariense and Hypericum grandifolium)

In the present work we carried out a phytochemical and biological investigation on three Hypericum species, i.e. Hypericum reflexum, Hypericum canariense and Hypericum grandifolium, from the Canary Islands where they are traditionally used as diuretic, wound healing, vermifuge, sedative and antidepressive agents. The polar extracts of the top flowering aerial parts, prepared by Soxhlet apparatus using a methanol-acetone (1:1) extracting mixture, were analyzed by HPLC-DAD and HPLC-MS for the content of eight biomarkers such as hypericin, hyperforin, chlorogenic acid, rutin, hyperoside, isoquercitrin, quercitrin and quercetin, whereas the hydrodistilled essential oils were analyzed by GC-FID and GC-MS. The three Hypericum species had different results in both polar and volatile constituents, H. reflexum being the only one endowed with a small amount of naphtodianthrones (hypericin and pseudohypericin), and containing high levels of chlorogenic acid, rutin and volatile mono- and sesquiterpenes. After chemical characterization, all products were in vitro biologically assayed for antiproliferative activity on human tumor cell lines by MTT assay, for antioxidant potential by DPPH, ABTS and FRAP assays, and for antimicrobial activity by the agar disc diffusion and microdilution methods. Results revealed interesting bioactivities and differences between polar extracts and essential oils, with the former being endowed with significant antioxidant activity and the latter with comparable inhibition effects on the tumor cells (A375, MDA-MB 231 and HCT 116) to that of cisplatin.

New water-soluble polypyridine silver(I) derivatives of 1,3,5-triaza-7-phosphaadamantane (PTA) with significant antimicrobial and antiproliferative activities

The new series of silver(I) coordination polymers [Ag(N-N)(μ-PTA)]n(X)n (1, 2, 4-8, 10, 11) and discrete monomers [Ag(N-N)(PTA)2](X) (3, 9) {N-N = bpy (1-3), dtbpy (4), neocup (5, 6), phen (7-9), dione (10, 11); X = NO3 (1, 3, 5, 7, 9, 10), PF6 (2, 4, 6, 8, 11)} were generated by self-assembly reactions, in MeOH at ~25 °C, of AgNO3 or AgPF6 with 1,3,5-triaza-7-phosphaadamantane (PTA) and the corresponding polypyridines, namely 2,2'-bipyridine (bpy), 4,4'-di-tert-butyl-2,2'-bipyridine (dtbpy), 1,10-phenanthroline (phen), 2,9-dimethyl-1,10-phenanthroline (neocup) and 1,10-phenanthroline-5,6-dione (dione). The compounds were obtained as air and light stable solids and characterized by IR, (1)H and (31)P{(1)H} NMR spectroscopy, ESI(+)-MS and elemental analyses. The crystal structure of 1 was determined by single crystal X-ray diffraction analysis, revealing infinite one-dimensional (1D) linear chains driven by μ-PTA N,P-linkers. Apart from representing the first examples of the metal-PTA derivatives bearing polypyridine ligands, 1-11 also feature solubility in water (S(25°C) ≈ 4-18 mg mL(-1)). Selected compounds (1, 3, 5, 7, 9 and 10) were thus tested for their biological properties and found to exhibit significant antibacterial and antifungal activities, screened in vitro against the standard strains of Staphylococcus aureus, Staphylococcus pyogenes, Staphylococcus pneumoniae, Staphylococcus sanguinis, Staphylococcus mutans, Enterococcus faecalis, Pseudomonas aeruginosa, Escherichia coli and Candida albicans. Furthermore, the compounds 5, 7, 9 and 10 show a pronounced antiproliferative activity against human malignant melanoma (A375), and the effects on the inhibition of tumor cells in vitro are in agreement with the DNA-binding studies.

Antioxidant, antiproliferative and antimicrobial activities of the volatile oil from the wild pepper Piper capense used in Cameroon as a culinary spice

Wild pepper (Piper capense L.f., Piperaceae) is a spice traditionally used in western Cameroon to make soups called 'Nkui' and 'Nah poh'. In the present work, the essential oil hydrodistilled from fruits was analyzed by GC-FID and GC-MS, and for in vitro biological activities, namely cytotoxic, antioxidant and antimicrobial, by MTT, DPPH, ABTS and agar disc diffusion methods. The oil composition was dominated by monoterpene hydrocarbons (56.5%) responsible for the pepper odor, such as (beta-pinene (33.2%), sabinene (10.0%) and alpha-pinene (8.9%). The oil induced a concentration-dependent inhibitory effect on human tumor cells MDA-MB 231 (breast adenocarcinoma), A375 (malignant melanoma) and HCT116 (colon carcinoma), showing IC50 values of 26.3, 76.0 and 22.7 microg/ml, respectively. The oil showed total antioxidant activity with a Trolox equivalent antioxidant concentration (TEAC) value of 140 micromol/g. The essential oil of P. capense proved to be an effective scavenger of the ABTS+ radical, with an activity only about 30 times lower than that of Trolox. Moderate activity was observed against the Gram-positive species Staphylococcos aureus and Enterococcusfaecalis, and the yeast Candida albicans. The notable inhibition of some human tumor cells is worthy of further investigation to discover the possible mechanisms of action responsible for the observed cytotoxic effect of this essential oil.

Antioxidant, Antiproliferative and Antimicrobial Activities of the Volatile Oil from the Wild Pepper Piper capense Used in Cameroon as a Culinary Spice

Wild pepper (Piper capense L.f., Piperaceae) is a spice traditionally used in western Cameroon to make soups called ‘ Nkui’ and ‘ Nah poh’. In the present work, the essential oil hydrodistilled from fruits was analyzed by GC-FID and GC-MS, and for in vitro biological activities, namely cytotoxic, antioxidant and antimicrobial, by MTT, DPPH, ABTS and agar disc diffusion methods. The oil composition was dominated by monoterpene hydrocarbons (56.5%) responsible for the pepper odor, such as β-pinene (33.2%), sabinene (10.0%) and α-pinene (8.9%). The oil induced a concentration-dependent inhibitory effect on human tumor cells MDA-MB 231 (breast adenocarcinoma), A375 (malignant melanoma) and HCT116 (colon carcinoma), showing IC50 values of 26.3, 76.0 and 22.7 μg/ml, respectively. The oil showed total antioxidant activity with a Trolox equivalent antioxidant concentration (TEAC) value of 140 μmol/g. The essential oil of P. capense proved to be an effective scavenger of the ABTS+ radical, with an activity only about 30 times lower than that of Trolox. Moderate activity was observed against the Gram-positive species Staphylococcos aureus and Enterococcus faecalis, and the yeast Candida albicans. The notable inhibition of some human tumor cells is worthy of further investigation to discover the possible mechanisms of action responsible for the observed cytotoxic effect of this essential oil.

Chemical composition and in vitro biological activities of the essential oil of Vepris macrophylla (BAKER) I.VERD. endemic to Madagascar

Vepris macrophylla is an evergreen tree occurring in sub-humid forest of Madagascar and traditionally used in the Island to treat several complaints as well as to prepare aromatic teas and alcoholic drinks. In the present work, the essential oil distilled from the leaves was analyzed for the first time by gas chromatography (GC-FID) and gas chromatography/mass spectrometry (GC/MS). The major compounds were citral (56.3%), i.e., mixture of neral (23.1%) and geranial (33.2%), citronellol (14.5%), and myrcene (8.3%). The essential oil exhibited antimicrobial activity against S. aureus, P. aeruginosa, and C. albicans as determined by vapor-diffusion assay, supporting the traditional use of the plant for preparing steam bath for the treatment of infectious diseases. The essential oil was evaluated for cytotoxic activity on human tumor cell lines by MTT (=3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) assay, showing inhibitory effects comparable to those of cisplatin, notably on MDA-MB 231 (human breast adenocarcinoma) and HCT116 (human colon carcinoma) cell lines. Finally, the essential oil was also subjected to screening for its antioxidant activity and the free radical scavenging capacity.

Characterization of levofloxacin non-susceptible clinical Streptococcus pyogenes isolated in the central part of Italy

We investigated the prevalence, genetics, and clonality of fluoroquinolone non-susceptible isolates of Streptococcus pyogenes in the central part of Italy. S. pyogenes strains (n = 197) were isolated during 2012 from patients with tonsillopharyngitis, skin, wound or invasive infections and screened for fluoroquinolone non-susceptibility (resistance to norfloxacin and levofloxacin minimum inhibitory concentration (MIC) = 2 mg/L) following EUCAST guidelines. First-step topoisomerase parC and gyrA substitutions were investigated using sequencing analysis. Clonality was determined by pulsed field gel electrophoresis (PFGE; SmaI digestion) and by emm typing. The fluoroquinolone non-susceptible phenotype was identified in 18 isolates (9.1 %) and correlated with mutations in parC, but not in gyrA, the most frequent leading to substitution of the serine at position 79 with an alanine. Most of the fluoroquinolone non-susceptible isolates belonged to the emm-type 6, even if other emm-types were also represented (emm75, emm89, and emm2). A significant level of association was measured between PFGE and both emm type and substitutions in parC. The prevalence of fluoroquinolone non-susceptible Streptococcus pyogenes isolates in Italy is of concern and, although the well-known emm type 6 is dominant, other types are appearing and spreading.

Phytochemical analysis, biological evaluation and micromorphological study of Stachys alopecuros (L.) Benth. subsp. divulsa (Ten.) Grande endemic to central Apennines, Italy

Stachys alopecuros subsp. divulsa (Lamiaceae), a perennial herb endemic to central Italy growing on mountain pastures, was investigated for the first time for the content of secondary metabolites, for the micromorphology and histochemistry of glandular trichomes, and for the biological activity of the volatile oil, namely cytotoxic, antioxidant and antimicrobial. The plant showed the molecular pattern of iridoids, among which a new iridoid diglycoside (4'-O-β-D-galactopyranosyl-teuhircoside) was detected, together with a sterol glucoside and a phenylethanoid glycoside. The essential oil from the flowering aerial parts was characterized by a high proportion of sesquiterpene hydrocarbons (65.1%), with (E)-caryophyllene (33.2%) as the most abundant, while other main components were germacrene D (7.6%), α-humulene (6.4%) and the oxygenated cis-sesquisabinene hydrate (10.2%). Taken together, polar and apolar chemical profiles support the classification of the species within the section Betonica of the genus Stachys. Micromorphological study revealed three types of glandular hairs secreting different classes of compounds, with type A peltate hairs producing the bulk of the essential oil. MTT assay revealed the potential of the volatile oil in inhibiting A375, HCT116 and MDA-MB 231 tumor cells (IC₅₀ values below 20 μg/ml).

The antibiotic Furvina® targets the P-site of 30S ribosomal subunits and inhibits translation initiation displaying start codon bias

Furvina®, also denominated G1 (MW 297), is a synthetic nitrovinylfuran [2-bromo-5-(2-bromo-2-nitrovinyl)-furan] antibiotic with a broad antimicrobial spectrum. An ointment (Dermofural®) containing G1 as the only active principle is currently marketed in Cuba and successfully used to treat dermatological infections. Here we describe the molecular target and mechanism of action of G1 in bacteria and demonstrate that in vivo G1 preferentially inhibits protein synthesis over RNA, DNA and cell wall synthesis. Furthermore, we demonstrate that G1 targets the small ribosomal subunit, binds at or near the P-decoding site and inhibits its function interfering with the ribosomal binding of fMet-tRNA during 30S initiation complex (IC) formation ultimately inhibiting translation. Notably, this G1 inhibition displays a bias for the nature (purine vs. pyrimidine) of the 3′-base of the codon, occurring efficiently only when the mRNA directing 30S IC formation and translation contains the canonical AUG initiation triplet or the rarely found AUA triplet, but hardly occurs when the mRNA start codon is either one of the non-canonical triplets AUU or AUC. This codon discrimination by G1 is reminiscent, though of opposite type of that displayed by IF3 in its fidelity function, and remarkably does not occur in the absence of this factor.

In vitro antibacterial activity of different adenosine analogues

Nucleoside analogues may represent good candidates for the discovery of new antibacterial agents, therefore, a library of adenosine analogues was assessed for their antibacterial activity, and the relationship between the structure and activity of these molecules was outlined. Antibacterial activity was evaluated against that of reference strains of Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Escherichia coli and Pseudomonas aeruginosa. We tested 54 adenosine analogues, modified both at ribose and base moieties, including adenine and 1/3-deazaadenine derivatives substituted in the 2- and/or N(6)-positions and bearing N-9 sugar moieties, such as ribose, 2'-deoxyribose, 3'-deoxyribose, 2',3'-dideoxyribose or cycloalkyl groups like cyclopentane. The data obtained, MIC and minimal bactericidal concentrations demonstrated that the presence of bulky substituents such as cycloheptyl and cyclooctyl rings on the N(6)-amino, together with a chlorine atom in the 2-position, conferred antibacterial activity against the Gram-positive group with MIC values ranging from 16 to 128 mg l(-1). The intact sugar moiety seemed to be not essential for antimicrobial activity and nucleosides bearing deoxyribose or cyclopentyl groups associated with bulky substituents in N(6)-position showed good antimicrobial properties. Furthermore, N-1 proved to be non-crucial and the 2-chloro-N(6)-cyclooctyl-1-deaza-3'-deoxyadenosine and 2',3'-dideoxyadenosine compounds were among the more active in the series with an MIC of 32 mg l(-1) against Staph. aureus and Strep. pneumoniae. None of the analogues was active against the two gram-negative species tested. Hence, adenosine derivatives bearing bulky substituents in the N(6)-position may represent good lead compounds for the future discovery of a novel series of antibacterial agents.

Erythrocyte aggregation in patients with systemic lupus erythematosus

Systemic Lupus Erythematosus (SLE) is an autoimmune, chronic inflammatory, non-organ specific disease. SLE patients present a high prevalence of thrombotic and arteriosclerotic disease. The aim of the present work was to study the erythrocyte aggregation kinetics, and the effect of plasma factors, namely, immunoglobulin and fibrinogen concentration, as well as cell factors such as deformability and erythrocyte membrane lipid fluidity on the erythrocyte aggregation, in SLE patients and healthy controls. The results show that SLE patients red blood cells aggregate at higher rate and the aggregates size are also greater than controls due to an increase of immunoglobulin and plasma fibrinogen. The negative correlation between aggregation parameters and rigidity index could point out that the altered deformability diminishes the erythrocyte aggregation. Correlation between rigidity index and anisotropy suggests that the decrease of membrane lipid fluidity might be a cause of deformability decrease. The erythrocyte aggregation increase in these patients could induce a decreased flow that might contribute to the thromboembolic process present in SLE patients.

Synthesis, antimicrobial and antiproliferative activity of novel silver(I) tris(pyrazolyl)methanesulfonate and 1,3,5-triaza-7-phosphadamantane complexes

Five new silver(I) complexes of formulas [Ag(Tpms)] (1), [Ag(Tpms)(PPh(3))] (2), [Ag(Tpms)(PCy(3))] (3), [Ag(PTA)][BF(4)] (4), and [Ag(Tpms)(PTA)] (5) {Tpms = tris(pyrazol-1-yl)methanesulfonate, PPh(3) = triphenylphosphane, PCy(3) = tricyclohexylphosphane, PTA = 1,3,5-triaza-7-phosphaadamantane} have been synthesized and fully characterized by elemental analyses, (1)H, (13)C, and (31)P NMR, electrospray ionization mass spectrometry (ESI-MS), and IR spectroscopic techniques. The single crystal X-ray diffraction study of 3 shows the Tpms ligand acting in the N(3)-facially coordinating mode, while in 2 and 5 a N(2)O-coordination is found, with the SO(3) group bonded to silver and a pendant free pyrazolyl ring. Features of the tilting in the coordinated pyrazolyl rings in these cases suggest that this inequivalence is related with the cone angles of the phosphanes. A detailed study of antimycobacterial and antiproliferative properties of all compounds has been carried out. They were screened for their in vitro antimicrobial activities against the standard strains Enterococcus faecalis (ATCC 29922), Staphylococcus aureus (ATCC 25923), Streptococcus pneumoniae (ATCC 49619), Streptococcus pyogenes (SF37), Streptococcus sanguinis (SK36), Streptococcus mutans (UA159), Escherichia coli (ATCC 25922), and the fungus Candida albicans (ATCC 24443). Complexes 1-5 have been found to display effective antimicrobial activity against the series of bacteria and fungi, and some of them are potential candidates for antiseptic or disinfectant drugs. Interaction of Ag complexes with deoxyribonucleic acid (DNA) has been studied by fluorescence spectroscopic techniques, using ethidium bromide (EB) as a fluorescence probe of DNA. The decrease in the fluorescence of DNA-EB system on addition of Ag complexes shows that the fluorescence quenching of DNA-EB complex occurs and compound 3 is particularly active. Complexes 1-5 exhibit pronounced antiproliferative activity against human malignant melanoma (A375) with an activity often higher than that of AgNO(3), which has been used as a control, following the same order of activity inhibition on DNA, i.e., 3 > 2 > 1 > 5 > AgNO(3)≫ 4.

A study on erm(B)-mediated MLS resistance in Streptococcus pyogenes clinical isolates

The constitutive or inducible macrolide-lincosamide-streptogramin (MLS) phenotype of 30 erm(B)-positive Streptococcus pyogenes isolates was determined by different methods and under various growth conditions and correlated to the sequence of the 5'-untranslated regions of erm(B). The MLS phenotype of one-third of the isolates could not be classified. In liquid medium, some of these isolates responded to induction only during the logarithmic phase of growth, while others expressed clindamycin resistance even under noninducing conditions. By increasing the growth rate, we observed a shift from a constitutive towards an inducible pattern of resistance. All data were confirmed by analysis of the 23S rRNA methylation level. The erm(B)-5'-untranslated region was 99% similar in sequence. In erm(B)-positive S. pyogenes, the MLS phenotype is strongly influenced by culture conditions and control of its expression does not depend exclusively on the sequence of the erm(B)-5'-untranslated region.

Antibacterial activity and anti-biofilm effect of chitosan against strains of Streptococcus mutans isolated in dental plaque

Streptococcus mutans is the major cause of dental plaque and is often associated with biofilm formation. The aim of this study is to evaluate the activity of a hydrosoluble derivative of chitosan against S. mutans biofilms in vitro and in vivo. Strains of S. mutans were isolated from the dental plaque of 84 patients enrolled in the study. The antibacterial activity of chitosan was determined by broth microdilutions. The effect of chitosan at different concentrations and exposure times on S. mutans biofilms at different phases of development was assessed by a clinical study using the classical "4-day plaque regrowth" experiment in adult volunteers. The MIC values of chitosan were between 0.5 and 2 g/L. Compared to distilled water, the chitosan solution significantly decreased the vitality of plaque microflora (p<or=0.05). Chlorhexidine, used as a positive control, reduced vitality even further. The results showed that S. mutans in the adhesion phase (4 h) was completely inhibited by chitosan at any concentration (0.1, 0.2, 0.5XMIC) or exposure time investigated (1, 15, 30, 60 min), while S. mutans at successive stages of accumulation (12-24 h) was inhibited only by higher concentrations and longer exposure times. These data confirm the effective action of chitosan against S. mutans biofilms.

Characterization of a Staphylococcus Aureus Strain Showing High Levels of Biofilm Formation Isolated from a Vascular Graft: Case Report

A methicillin-susceptible Staphylococcus aureus strain, SA-DZ1, was isolated from an infected bypass crossover graft. Its general microbiological features were reminiscent of those previously described for the wound Wiley strain. Removal of the prosthetic device was necessary to resolve the infection. SA-DZ1 grown under different conditions showed a very strong and distinctive biofilm-producing phenotype, which was also visualized by confocal laser scanning microscopy. The biofilm extracellular matrix was essentially polysaccharidic, as determined by differential growth and physicochemical tests. By Multi Locus Sequence Typing (MLST), SA-DZ1 was classified as st94, a single locus variant of st8. Several other genetic traits assayed by PCR, such as agr-type and the presence of gene encoding proteins involved in adhesion and virulence (e.g. ica operon), confirmed the identifying features of this clinical isolate.