Agata Dorotkiewicz-Jach

Liposomes as delivery systems for antibiotics

Liposomes are currently in common use as universal drug carriers in the cosmetic and pharmaceutical industries. The manipulation of different physicochemical properties of liposomes enables the design of particular carriers with the desired pharmacokinetic and pharmacodynamic properties. Most studies regarding liposomal antibiotics deal with aminoglycosides, quinolones, polypeptides, and betalactames. Some of the studies focused on improving pharmacokinetics and reducing toxicity, while others involved enhancing antibacterial activity. In an era of an avalanche of increasing bacterial resistance and severe problems in treating bacterial infections, the application of liposomal antibiotic carriers could be useful, but the high cost of liposome preparation and treatment should also be considered.

The interaction between Pseudomonas aeruginosa cells and cationic PC:Chol:DOTAP liposomal vesicles versus outer-membrane structure and envelope properties of bacterial cell

The interactions between cationic liposomal formulations (PC:Chol:DOTAP 3:4:3) and 23 Pseudomonas aeruginosa strains were tested. The study was undertaken because different antimicrobial results had been obtained by the authors for Pseudomonas aeruginosa strains and liposomal antibiotics (Drulis-Kawa, Z., Gubernator, J., Dorotkiewicz-Jach, A., Doroszkiewicz, W., Kozubek, A., 2006. The comparison of in vitro antimicrobial activity of liposomes containing meropenem and gentamicin. Cell. Mol. Biol. Lett., 11, 360-375; Drulis-Kawa, Z., Gubernator, J., Dorotkiewicz-Jach, A., Doroszkiewicz W., Kozubek, A., 2006. In vitro antimicrobial activity of liposomal meropenem against Pseudomonas aeruginosa strains. Int. J. Pharm., 315, 59-66). The experiments evaluate the roles of the bacterial outer-membrane structure, especially outer-membrane proteins and LPS, and envelope properties (hydrophobicity and electrostatic potential) in the interactions/fusion process between cells and lipid vesicles. The interactions were examined by fluorescent microscopy using PE-rhodamine-labelled liposomes. Some of the strains exhibited red-light emission (fusion with vesicles or vesicles surrounding the cell) and some showed negative reaction (no red-light emission). The main aim of the study was to determine what kinds of bacterial structure or envelope properties have a major influence on the fusion process. Negatively charged cells and hydrophobic properties promote interaction with cationic lipid vesicles, but no specific correlation was noted for the tested strains. A similar situation concerned LPS structure, where parent strains and their mutants possessing identical ladder-like band patterns in SDS-PAGE analysis exhibited totally different results with fluorescent microscopy. Outer-membrane protein analysis showed that an 18-kDA protein occurred in the isolates showing fusion with rhodamine-labelled vesicles and, conversely, strains lacking the 18-kDA protein exhibited no positive reaction (red emission). This suggests that even one protein may be responsible for favouring stronger interactions between Pseudomonas aeruginosa cells and cationic liposomal formulations (PC:Chol:DOTAP 3:4:3).

Isolation and characterisation of KP34—a novel φKMV-like bacteriophage for Klebsiella pneumoniae

Bacteriophage KP34 is a novel virus belonging to the subfamily Autographivirinae lytic for extended-spectrum β-lactamase-producing Klebsiella pneumoniae strains. Its biological features, morphology, susceptibility to chemical and physical agents, burst size, host specificity and activity spectrum were determined. As a potential antibacterial agent used in therapy, KP34 molecular features including genome sequence and protein composition were examined. Phylogenetic analyses and clustering of KP34 phage genome sequences revealed its clear relationships with “phiKMV-like viruses”. Simultaneously, whole-genome analyses permitted clustering and classification of all phages, with completely sequenced genomes, belonging to the Podoviridae.

A COMPARISON OF THE in vitro ANTIMICROBIAL ACTIVITY OF LIPOSOMES CONTAINING MEROPENEM AND GENTAMICIN

The antimicrobial activity of eight cationic, two neutral and three anionic liposome compositions containing meropenem and gentamicin was tested in vitro in broth and serum medium. The cationic formulations showed better antibacterial efficacy against both Gram-positive and Gram-negative bacteria than the anionic and neutral ones, regardless of the encapsulated drug. The most effective formulations were the cationic PC/DOPE/DOTAP 3:4:3 and PC/Chol/DOTAP 3:4:3, as the MICs with meropenem were 2 to 4 times lower than those of the free drug.

Modern Therapeutic Approaches Against Pseudomonas aeruginosa Infections.

Despite the enormous progress that has been made in the last few decades in the field of drug design as well as virulence of pathogenic bacteria, the gradual spread of drug resistance can be observed. Only two new classes of antibiotics have been brought to medicine in the last 30 years. The need for novel antibacterial drugs is especially pressing when considering infections caused by multidrug-resistant (MDR) pathogens such as Pseudomonas aeruginosa. The discovery and development of new anti-pseudomonal therapies is one of the main challenges of modern pharmaceutical sciences. The great variety of innovative approaches presented in the current literature is astonishing. In this review, modern, promising strategies against P. aeruginosa infections are described. Antimicrobials, including new antibiotics, β-lactamase and efflux pump inhibitors, quorum quenching molecules and nanoparticles with antibacterial activity are currently being intensively studied. Methods of prevention of infection through vaccines, therapeutic antibodies and development of antimicrobial peptides are discussed as approaches that support the human immunological system. Finally, development of alternative/ supportive therapies such as phage therapy and photodynamic therapy, in which the mechanism of action is completely different from current antibiotic therapy, is of great importance.

Bactericidal activities of GM flax seedcake extract on pathogenic bacteria clinical strains

BackgroundThe antibiotic resistance of pathogenic microorganisms is a worldwide problem. Each year several million people across the world acquire infections with bacteria that are antibiotic-resistant, which is costly in terms of human health. New antibiotics are extremely needed to overcome the current resistance problem.ResultsTransgenic flax plants overproducing compounds from phenylpropanoid pathway accumulate phenolic derivatives of potential antioxidative, and thus, antimicrobial activity. Alkali hydrolyzed seedcake extract containing coumaric acid, ferulic acid, caffeic acid, and lignan in high quantities was used as an assayed against pathogenic bacteria (commonly used model organisms and clinical strains). It was shown that the extract components had antibacterial activity, which might be useful as a prophylactic against bacterial infection. Bacteria topoisomerase II (gyrase) inhibition and genomic DNA disintegration are suggested to be the main reason for rendering antibacterial action.ConclusionsThe data obtained strongly suggest that the seedcake extract preparation is a suitable candidate for antimicrobial action with a broad spectrum and partial selectivity. Such preparation can be applied in cases where there is a risk of multibacterial infection and excellent answer on global increase in multidrug resistance in pathogenic bacteria.

Defensive and offensive cross-reactive antibodies elicited by pathogens: the Good, the Bad and the Ugly

Understanding how immunity to pathogens develops is crucial for progress in the quest for effective vaccines. Intraspecies and interspecies cross-reacting antibodies are produced in high frequency against immune-relevant and shared microbial epitopes. It has been confirmed that cross-reactive antigens may have a crucial role in natural epidemiology to a particular infection and that cross-protection may influence the outcome of natural infections. On the other hand, the action of cross-reactive antibodies may be very harmful for the host. In this review we discuss both the defensive and offensive capabilities of cross-reactive antibodies. The defensive properties are discussed with regard to the beneficial cross-protective interaction of these antibodies against various microorganisms including viruses, bacteria, fungi and protozoan parasites. We summarize the current knowledge of numerous effector functions of these antibodies such as agglutination, neutralization of infectivity, complement activation, phagocytosis enhancement, and antibody-dependent cellular cytotoxicity. We also discuss the offensive action of cross-reactive antibodies including their detrimental effects in exacerbation of the infective diseases, as well as autoimmune diseases and allergy as a result of inappriopriate or deleterious inflammatory response associated with host tissue destruction. The factors influencing cross-protective capacity of antibodies are also presented.

Complex Signaling Networks Controlling Dynamic Molecular Changes in Pseudomonas aeruginosa Biofilm

The environment exerts strong influence on microbes. Adaptation of microbes to changing conditions is a dynamic process regulated by complex networks. Pseudomonas aeruginosa is a life-threating, versatile opportunistic and multi drug resistant pathogen that provides a model to investigate adaptation mechanisms to environmental changes. The ability of P. aeruginosa to form biofilms and to modify virulence in response to environmental changes are coordinated by various mechanisms including two-component systems (TCS), and secondary messengers involved in quorum sensing (QS) and c-di-GMP networks (diguanylate cyclase systems, DGC). In this review, we focus on the role of c-di-GMP during biofilm formation. We describe TCS and QS signal cascades regulated by c-di-GMP in response to changes in the external environment. We present a complex signaling network dynamically changing during the transition of P. aeruginosa from the free-living to sessile mode of growth.