Antibactericidal Ir(III) and Ru(II) Complexes with Phosphine-Alkaloid Conjugate and Their Interactions with Biomolecules: A Case of N-Methylphenethylamine.

The phosphine ligand (Ph2 PCH2 N(CH3 )(CH2 )2 Ph, PNMPEA) obtained by the reaction of the (hydroxymethyl)diphenylphosphine with naturally occurring alkaloid N-methylphenethylamine, was used to synthesize the half-sandwich iridium(III) (Ir(η5 -Cp*)Cl2 Ph2 PCH2 N(CH3 )(CH2 )2 Ph, IrPNMPEA) and ruthenium(II) (Ru(η6 -p-cymene)Cl2 Ph2 PCH2 N(CH3 )(CH2 )2 Ph, RuPNMPEA) complexes. They were characterized using a vast array of methods, including 1D and 2D NMR, ESI(+)MS spectrometry, elemental analysis, cyclic voltammetry (CV), electron spectroscopy in the UV-Vis range (absorption, fluorescence) and density functional theory (DFT). The initial antimicrobial activity in vitro toward Gram-positive and Gram-negative bacterial strains was examined, indicating that both complexes are selective towards Gram-positive bacteria, e. g., Staphylococcus aureus, where the IrPNMPEA has been more bactericidal compared to RuPNMPEA. Additionally, the interactions of these compounds with various biomolecules, such as DNA (ctDNA, plasmid DNA, 9-ethylguanine (9-EtG), and 9-methyladenine (9-MeA)), nicotinamide adenine dinucleotide (NADH), glutathione (GSH), and ascorbic acid (Asc) were described. The results showed that both Ir(III) and Ru(II) complexes accelerate the oxidation process of NADH, GSH and Asc that appeared to occur by an electron transfer mechanism. Interestingly, only IrPNMPEA leads to the formation of various biomolecule adducts, which can explain its higher activity. Furthermore, RuPNMPEA and IrPNMPEA have been interacting with the DNA through weak noncovalent interactions.

Sensitivity of Ixodes ricinus (L., 1758) and Dermacentor reticulatus (Fabr., 1794) ticks to entomopathogenic fungi isolates: preliminary study.

Entomopathogenic fungi of the genus Beauveria and Metarhizium play an important role in controlling the population of arthropods. However, the data on their effectiveness against ticks focus mainly on species that do not occur in Europe. The aim of the study was to assess the effectiveness of entomopathogenic fungi against two of the most important tick species in Europe: Ixodes ricinus and Dermacentor reticulatus. In our study, the majority of tested entomopathogenic fungi strains showed potential efficacy against both tick species; however, D. reticulatus was less susceptible in comparison to I. ricinus. The observed mortality of ticks was up to 100% by using all commercial strains as well as three out of nine of the environmental strains. Among all tested fungi, the most effective against both tick species was environmental strain Metarhizium anisopliae LO4(1) with LC50 values: 2.6 × 103 cfu/ml-5.7 × 105 cfu/ml. Botanigard proved to be more effective than MET52 with LC50 values: 6.8 × 103 cfu/ml-3.3 × 106 cfu/ml. The conducted bioassays indicate the potential possibility of using the environmental isolates of entomopathogenic fungi, as well as commercial strains in control of local populations of I. ricinus and D. reticulatus; however, the possibility of using them in vivo requires more research.

Antibacterial activity and action mode of Cu(I) and Cu(II) complexes with phosphines derived from fluoroquinolone against clinical and multidrug-resistant bacterial strains.

Biological activity against reference and multi-drug resistant (MDR) clinical strains of fluoroquinolones (FQs): ciprofloxacin (HCp), norfloxacin (HNr), lomefloxacin (HLm) and sparfloxacin (HSf), phosphine ligands derived from those antibiotics and 14 phosphino copper(I) and copper(II) complexes with 2,9-dimethyl-1,10-phenanthroline, 1,10-phenanthroline or 2,2'-biquinoline have been determined. Almost all phosphines showed excellent antibacterial activity relative to reference strains (S. aureus ATCC 6538, E. coli ATCC 25922, K. pneumoniae ATCC 4352, and P. aeruginosa ATCC 27853). In rare cases P. aeruginosa rods showed natural insensitivity to oxides, and their copper(II) complexes. Most of the studied compounds showed weak antibacterial activity against clinical multi-drug resistant strains (MDR P. aeruginosa 16, 46, 325, 355, MRD A. baumanii 483 and MDR S. aureus 177). However, phosphines Ph2PCH2Sf (PSf), Ph2PCH2Lm (PLm) and their copper(I) complexes were characterized by the best antibacterial activity. In addition, PSf compounds, in which the activities relative to P. aeruginosa MDRs were relatively diverse, paid particular attention in our studies. Genetic and phenotypic studies of these strains showed significant differences between the strains, indicating different profiles of FQs resistance mechanisms. This may prove that a change in the spatial conformation of the PSf derivatives relative to the native form of HSf increased its affinity for the target site of action in gyrase, leading to selective inhibition of the multiplication of MDR strains. In conclusion, differences in PSf activity within closely related P. aeruginosa strains may indicate its diagnostic and therapeutic potential.

Sensitivity of Ixodes ricinus (L., 1758) and Dermacentor reticulatus (Fabr., 1794) ticks to Bacillus thuringiensis isolates: preliminary study.

Bacillus thuringiensis is a highly specific entomopathogenic microorganism. Although defined as having properties which work against insects, its role in the control of tick populations is still insufficiently known. In our bioassay, four environmental strains of B. thuringiensis, along with one commercially available product (Vectobac), have been used against ticks. Vectobac turned out to be ineffective in the biocontrol of ticks; however, two of environmental B. thuringiensis strains proved to be efficient against both Ixodes ricinus and Dermacentor reticulatus. In those cases, the mortality rate for ticks was assessed as being up to 80%, and LC50 ranged between 9.1 × 106 and 1.3 × 1015 (cfu/ml). Dermacentor reticulatus males were the most sensitive to bacteria. The similarity between the most and least efficient B. thuringiensis strains in enzymatic profiles-including lipases, phosphatases, proteases, and chitinases-may indicate a limited role of detected enzymes in the pathogenicity profile of bacterial strains against ticks.

Identification of Yersinia enterocolitica isolates from humans, pigs and wild boars by MALDI TOF MS.

BACKGROUND: Yersinia enterocolitica is widespread within the humans, pigs and wild boars. The low isolation rate of Y. enterocolitica from food or environmental and clinical samples may be caused by limited sensitivity of culture methods. The main goal of present study was identification of presumptive Y. enterocolitica isolates using MALDI TOF MS. The identification of isolates may be difficult due to variability of bacterial strains in terms of biochemical characteristics. This work emphasizes the necessity of use of multiple methods for zoonotic Y. enterocolitica identification. RESULTS: Identification of Y. enterocolitica isolates was based on MALDI TOF MS, and verified by VITEK® 2 Compact and PCR. There were no discrepancies in identification of all human' and pig' isolates using MALDI TOF MS and VITEK® 2 Compact. However three isolates from wild boars were not decisively confirmed as Y. enterocolitica. MALDI TOF MS has identified the wild boar' isolates designated as 3dz, 4dz, 8dz as Y. enterocolitica with a high score of matching with the reference spectra of MALDI Biotyper. In turn, VITEK® 2 Compact identified 3dz and 8dz as Y. kristensenii, and isolate 4dz as Y. enterocolitica. The PCR for Y. enterocolitica 16S rDNA for these three isolates was negative, but the 16S rDNA sequence analysis identified these isolates as Y. kristensenii (3dz, 4dz) and Y. pekkanenii (8dz). The wild boar' isolates 3dz, 4dz and 8dz could not be classified using biotyping. The main bioserotype present within pigs and human faeces was 4/O:3. It has been shown that Y. enterocolitica 1B/O:8 can be isolated from human faeces using ITC/CIN culturing. CONCLUSION: The results of our study indicate wild boars as a reservoir of new and atypical strains of Yersinia, for which protein and biochemical profiles are not included in the MALDI Biotyper or VITEK® 2 Compact databases. Pigs in the south-west Poland are the reservoir for pathogenic Y. enterocolitica strains. Four biochemical features included in VITEK® 2 Compact known to be common with Wauters scheme were shown to produce incompatible results, thus VITEK® 2 Compact cannot be applied in biotyping of Y. enterocolitica.

Antibacterial Activity of Alanine-Derived Gemini Quaternary Ammonium Compounds.

The antibacterial activity of alanine-derived gemini quaternary ammonium salts (chlorides and bromides) with various spacer and alkyl chain lengths was investigated. The studied compounds exhibited a strong bactericidal effect, especially bromides with 10 and 12 carbon alkyl chains and 3 carbon spacer groups (TMPAL-10 Br and TMPAL-12 Br), with a short contact time. Both salts dislodged biofilms of Pseudomonas aeruginosa and Staphylococcus epidermidis, and were lethal to adherent cells of S. epidermidis. Bromide with 2 carbon spacer groups and 12 carbon alkyl chains (TMEAL-12 Br) effectively reduced microbial adhesion by coating polystyrene and silicone surfaces. The results obtained suggest that, after further studies, gemini QAS might be considered as antimicrobial agents in medicine or industry.

Presumable role of outer membrane proteins of Salmonella containing sialylated lipopolysaccharides serovar Ngozi, sv. Isaszeg and subspecies arizonae in determining susceptibility to human serum.

BACKGROUND: The O48 group comprises Salmonella bacteria containing sialic acid in the lipopolysaccharide (LPS). Bacteria with sialylated surface structures are described as pathogens that avoid immunological response of the host by making similar their surface antigens to the host's tissues (molecular mimicry). It is known that the smooth-type LPS of Salmonella enterica and outer membrane proteins (OMP) PgtE, PagC and Rck mediate serum resistant phenotype by affecting complement system (C). The aim of this study was to investigate C3 component activation by Salmonella O48 LPS and OMP. FINDINGS: In the present study, we examined C3 component deposition on the three Salmonella O48 strains: S. enterica subspecies enterica serovar Ngozi, S. enterica subsp. enterica sv. Isaszeg, and S. enterica subsp. arizonae containing sialic acid in the O-specific part of LPS. The greatest C3 deposition occurred on Salmonella sv. Isaszeg cells (p < 0.005) as well as on their LPS (low content of sialic acid in LPS) (p < 0.05) after 45 min of incubation in 50% human serum. Weaker C3 deposition ratio on the Salmonella sv. Ngozi (high content of sialic acid in LPS) and Salmonella subsp. arizonae (high content of sialic acid in LPS) cells correlated with the lower C3 activation on their LPS. Immunoblotting revealed that OMP isolated from the tested strains also bound C3 protein fragments. CONCLUSIONS: We suggest that activation of C3 serum protein is dependent on the sialic acid contents in the LPS as well as on the presence of OMP in the range of molecular masses of 35-48 kDa.

Insight into tick biocontrol with special regard to fungi.

The epidemiological and epizootic importance of ticks has been known for a few decades since of the discovery of their role as vectors of many new diseases, and the better detection of those already known. Given the durability of chemical preparations in the environment and the increasing problem of developing tick resistance, natural strategies for biological control are sought. A promising alternative to chemical pesticides is the use of entomopathogenic organisms for effective integrated pest management of low environmental impact. A number of promising microbes have been identified during the search for effective means of controlling the tick population, but the knowledge about the impact of these pathogens on the environment and other non-target organisms is still insufficient. Previous research has still not provided a definite answer about the safety of their use. It is known, however,that the chemicals which are currently used have a negative impact on the environment and/or cause resistance. No efficient biocompound has yet been devised for commercial use. Potential microorganisms for tick biocontrol (mainly bacteria and fungi) are natural tick pathogens, living in the same environment. With their adhesive properties, and their ability to digest the cuticle, they may constitute an appropriate ingredient of bioacaricides. Until now, fungal insecticides have been used only to control crop pests.

Antibacterial activity of gemini quaternary ammonium salts.

A series of gemini quaternary ammonium salts (chlorides and bromides), with various hydrocarbon chain and spacer lengths, were tested. These compounds exhibited antibacterial activity against both Gram-positive and Gram-negative bacteria and were not mutagenic. The strongest antibacterial effect was observed for TMPG-10 Cl (against Pseudomonas aeruginosa ATCC 27853) and TMPG-12 Br (against Staphylococcus aureus ATCC 6538 and Escherichia coli ATCC 11229 and clinical ESBL(+) isolate 434) surfactants. These compounds inhibited the adhesion of Staphylococcus epidermidis ATCC 35984 to a polystyrene surface and eradicated biofilm formed by P. aeruginosa PAO1. The activity of studied compounds was dependent on hydrocarbon chain length.

Regulatory protein OmpR influences the serum resistance of Yersinia enterocolitica O:9 by modifying the structure of the outer membrane.

The EnvZ/OmpR two-component system constitutes a regulatory pathway involved in bacterial adaptive responses to environmental cues. Our previous findings indicated that the OmpR regulator in Yersinia enterocolitica O:9 positively regulates the expression of FlhDC, the master flagellar activator, which influences adhesion/invasion properties and biofilm formation. Here we show that a strain lacking OmpR grown at 37°C exhibits extremely high resistance to the bactericidal activity of normal human serum (NHS) compared with the wild-type strain. Analysis of OMP expression in the ompR mutant revealed that OmpR reciprocally regulates Ail and OmpX, two homologous OMPs of Y. enterocolitica, without causing significant changes in the level of YadA, the major serum resistance factor. Analysis of mutants in individual genes belonging to the OmpR regulon (ail, ompX, ompC and flhDC) and strains lacking plasmid pYV, expressing YadA, demonstrated the contribution of the respective proteins to serum resistance. We show that Ail and OmpC act in an opposite way to the OmpX protein to confer serum resistance to the wild-type strain, but are not responsible for the high resistance of the ompR mutant. The serum resistance phenotype of ompR seems to be multifactorial and mainly attributable to alterations that potentiate the function of YadA. Our results indicate that a decreased level of FlhDC in the ompR mutant cells is partly responsible for the serum resistance and this effect can be suppressed by overexpression of flhDC in trans. The observation that the loss of FlhDC enhances the survival of wild-type cells in NHS supports the involvement of FlhDC regulator in this phenotype. In addition, the ompR mutant exhibited a lower level of LPS, but this was not correlated with changes in the level of FlhDC. We propose that OmpR might alter the susceptibility of Y. enterocolitica O:9 to complement-mediated killing through remodeling of the outer membrane.

Reptiles as a source of Salmonella O48--clinically important bacteria for children: the relationship between resistance to normal cord serum and outer membrane protein patterns.

Bacteria of the Salmonella O48 somatic antigen group are clinically important strains causing intestinal dysfunction and diarrhoea, especially in children. The susceptibility of Salmonella O48 strains containing sialic acid (N-acetylneuraminic acid (NeuAc)) in lipopolysaccharide (LPS) to the bactericidal action of normal cord serum (NCS) was determined. The authors' previous results published in Microbial Ecology in 2010 indicated that neither the presence of NeuAc in LPS nor the length of the O-specific part of LPS containing NeuAc plays a decisive role in determining bacterial resistance to the bactericidal activity of normal human serum (NHS), and that the presence of NeuAc in the LPS structure is not sufficient to block the activation of the alternative pathway of complement in NHS. The current results showed that the tested strains showed various sensitivities also to the bactericidal action of NCS. The authors postulate that the presence of certain outer membrane proteins (OMPs) are characteristic of the resistant and sensitive phenotypes of Salmonella O48 strains. To establish a possible relationship between resistance to NCS and OMPs band patterns, ten Salmonella O48 strains were studied as follows: susceptibility to the bactericidal effect of NCS, the mechanisms of NCS activation and OMP band patterns obtained by sodium dodecyl sulphate-polyacrylamide gel electrophoresis.