Studies were conducted on the improvement of A. culicicola identification. This species is phenotypically very similar to A. veronii biotype sobria, A. sobria, and A. allosaccharophila. The sequences of 16S rDNA of A. culicicola isolates show the highest similarity with A. jandaei, A. veronii, and A. caviae. Digestion of 16S rDNA PCR product with Alul and Mbol restriction endonucleases allowed discriminating A. culicicola from all other Aeromonas species with the exception of A. jandaei. Additional digestion of 16S rDNA PCR product with BceAI showed a possibility of distinguishing A. jandaei from A. culicicola.
By functional complementation of a PDR 5 (pleiotropic drug resistance) null mutant of S. cerevisiae, we have recently cloned and sequenced a multidrug resistance gene CDR1 (Candida Drug Resistance). Transformation by CDR1 of a PDR 5 disrupted host hypersensitive to cycloheximide and chloramphenicol resulted in resistance to these as well as other unrelated drugs. The nucleotide sequence of CDR 1 revealed that, like PDR 5, it encodes a putative membrane pump belonging to the ABC superfamily. CDR 1 encodes a protein of 169.9 kDa whose predicted structural organisation is characterised by two homologous halves, each comprising a hydrophobic region, with a set of six transmembrane stretches, preceded by a hydrophilic binding fold. We now have evidence to suggest that there are several PDR homologues present in C. albicans which display multidrug resistance and a collateral sensitivity pattern different from PDR 5 and CDR 1. The functions of such genes and their products in the overall physiology of C. albicans is not yet established.
Ticks constitute important vectors of human and animal pathogens. Besides the Lyme borreliosis and tick-borne encephalitis, other pathogens such as Babesia spp., Rickettsia spp., and Anaplasma phagocytophilum, are of increasing public health interest. In Poland, as in other European countries, Ixodes ricinus, the most prevalent tick species responsible for the majority of tick bites in humans, is the main vector of A. phagocytophilum. The aim of the study was to estimate the infection level of I. ricinus with A. phagocytophilum in selected districts, not previously surveyed for the presence of this agent. Sampling of questing ticks was performed in 12 forested sites, located in four districts (Legnica, Milicz, Lubań, and Oława) in SW Poland. Altogether, 792 ticks (151 females, 101 males, and 540 nymphs) representing I. ricinus were checked for the presence of A. phagocytophilum. The average infection level was 4.3%, with higher rate reported for adult ticks. The highest percentage of infected adults was observed in Milicz (17.4%) and the lowest in Oława (6.8%). The abundance of questing I. ricinus in all examined sites as well as the infection with A. phagocytophilum indicate for the first time the risk for HGA transmission in SW Poland.
During one year study, 394 stool samples obtained from a random cases of diarrhea were examined for the presence of free shiga-like toxins Stx1 and Stx2 in Vero cells assay. Of 394 stool specimen supernatants tested, 2 (0.5%) gave positive results. The two stool supernatants positive on Vero cell line were wholly capable of being neutralized with the monoclonal antibody to Stx2. Broth cultures of strains isolated from the two positive stool samples were negative for Stxs-production in Vero cytotoxicity assay and by PCR.
The antibacterial activity of synthetic aliphatic and aromatic monoacylglycerols (MAGs) was studied against two human pathogens: Staphylococcus aureus and Esherichia coll. The active compounds inhibited selectively S. aureus. The most active compounds amongst them were those with medium size aliphatic chain and aromatic MAGs with electron withdrawing substituents at the aryl ring. The introduction of one or two-carbon spacer between the aryl ring and the carboxylic function did not influence antibacterial effectiveness.
Yersinia enterocolitica is a human pathogen that causes gastroenteric infections. Various environmental signals control the expression of the virulence factors in pathogenic Y. enterocolitica strains. OmpR, a global transcriptional regulator controls the expression of a wide spectrum of genes, some of which are required for virulence. In this study, we amplified, cloned and sequenced a Y. enterocolitica Ye9 ompR gene. Deduced amino acid sequence has been shown to have 98% homology to the Y. enterocolitica 0:8, Y. pestis, S. typhi and S. enterica serovar Typhimurium OmpR proteins. Additional cell culture experiments was performed to investigate whether OmpR takes part in the virulence of Y. enterocolittica. We found that the Y. enterocolitica ompR mutant was unable to invade HeLa cells. In conclusion, we have shown that OmpR is a very highly conserved protein among enteric bacterial pathogens which plays an important role in the Y. enterocolitica virulence.
One of virulence factors produced by Staphylococcus aureus is staphylokinase (SAK), which enhances their proteolytic activity leading to tissue damage and improving bacterial invasiveness. In the present study we estimated the ability to produce staphylokinase by 95 S. aureus reference strains and clinical isolates from the airways of cystic fibrosis patients, from skin lesions and from infected bones. We would like to verify any relationship between SAK production and the types of clinical isolates as well as other biochemical properties and activities of these staphylococcal strains, which can be important for their pathogenicity. More than 62% of all tested strains were able to produce secreted type of SAK. Staphylokinase production was significantly more common in the isolates from skin and soft tissue infections than in any other group of tested staphylococci. The general tendencies in the selected properties or activities of both SAK(-) and SAK(+) isolates were similar. Our data confirm phenotypic dissimilarity in SAK production of S. aureus strains isolated from various types of infections. It is compatible with the biological role of staphylokinase and with hypothetical model of staphylokinase mediated bacterial invasion of host tissues. Thus, the estimation of SAK production by S. aureus isolates may be regarded as the parameter describing potential invasiveness of staphylococci and can be useful as a medical recommendation for the eradication of staphylococci carrier state.
The γ-glutamyltranspeptidase (GGT) of Helicobacter pylori (HpGT) is a newly found virulence factor. In an approach to gain insight into the gene function, the four domains of the HpGT were cloned and expressed in baculovirus expression system. The results of a functional assay showed that the HpGT products acted as GGT, even when the N-terminal 380 amino acids were deleted. However, only the full length open reading frame (ORF) of the HpGT gene was apparently e$ective on cell growth. This result indicated that the products of the full length ORF might have an important role in gastric carcinogenesis. In this paper, we are the first to report that changes of mitochondrial membrane potential can be detected using 5, 5’, 6, 6’-tetrachloro-1, 1’, 3, 3’-tetraethylbenzimidazole carbocyanine iodide (JC-1) staining in insect cells.
The strains belonging to Burkholderia cepacia complex are important opportunistic pathogens in immunocompromised patients and cause serious diseases. It is possible to obtain isolates from soil, water, plants and human samples. Taxonomy of this group is difficult. Burkholderia cepacia complex consists of seventeen genomic species and the genetic scheme is based on recA gene. Commonly, first five genomovars occurre in humans, mostly genomovars II and III, subdivision IIIA. Within this study we tested identification of first five genomovars by PCR with following melting analysis and RFLP. The experiments were targeted on eubacterial 16S rDNA and specific gene recA, which allowed identification of all five genomovars. RecA gene appeared as more suitable than 16S rDNA, which enabled direct identification of only genomovars II and V; genomovars I, III and IV were similar within 16S rDNA sequence.
Proteases, also referred to as peptidases, are the enzymes that catalyse the hydrolysis of peptide bonds in polipeptides. A variety of biological functions and processes depend on their activity. Regardless of the organism’s complexity, peptidases are essential at every stage of life of every individual cell, since all protein molecules produced must be proteolytically processed and eventually recycled. Protease inhibitors play a crucial role in the required strict and multilevel control of the activity of proteases involved in processes conditioning both the physiological and pathophysiological functioning of an organism, as well as in host-pathogen interactions. This review describes the regulation of activity of bacterial proteases produced by dangerous human pathogens, focusing on the Staphylococcus genus.
The present work was conducted to investigate antibacterial activity of methanol and acetone in leaf (LE) and stem-bark (SBE) of Ficus sycomorus L. crude extracts against sensitive and resistant species of Staphylococcus aureus and Acinetobacter baumannii pathogens. Antimicrobial activity expressed by disc-diffusion method (zone of inhibitions – ZIs), minimum inhibitory concentrations (MICs) and minimum bactericidal concentration (MBC) were measured as reported for many investigations. Similar study with 6 commercial antibiotics as a reference drug was undertaken. Based upon the estimated ZIs, MIC and MBC values, acetone LE exhibited higher antimicrobial activity than that of methanol one. Otherwise, standard antibiotics have lower effectiveness (ZIs, MICs and MBC) on all tested bacteria as compared to the SBE and LE. The highest antibacterial activity was recorded in sensitive A. baumannii isolate with MICs 2.5, 4.9 mg/ml and MBC 3.8, 9.7 mg/ml for acetone LE and SBE, respectively. Our data indicated that the lowest antibiotics antibacterial activity was recorded for resistant A. baumannii pathogen. It was lower than those of the both plant fractions extracts.
The aim of this study was to identify the most common bacteria that may be found in the blood or on the feathers of white stork (Ciconia ciconia) chicks and predict their pathogenic potential for birds and humans. A variety of microorganisms, which include Staphylococcus aureus, Staphylococcus vitulinus, and Pseudomonas sp. were found. Based on breeding population densities and reproductive success over the past 25 years, we found no apparent effects of bacterial infections on the white stork population in Poland.
The interaction of Y. enterocolitica strains belonging to 4 and 1A biotypes with RAW264.7 murine macrophage- like cell monolayers was studied. Y. enterocolitica strains from humans and pigs were characterized in terms of their internalization and survival within RAW264.7 cell monolayers and their ability to escape from the cells. Y. enterocolitica biotype 4 strains invaded macrophage cell monolayers to a significantly higher degree than biotype 1A strains. However, biotype 1A strains exhibited a greater level of survival in macrophages than biotype 4 strains. All Y. enterocolitica strains tested demonstrated the ability to escape from macrophages. The mechanisms that allow Y. enterocolitica biotype 1A to survive within macrophages may contribute to the virulence of these organisms
The application of random amplified polymorphic DNA- polymerase chain reaction (RAPDPCR) was found to be a simple, cheap and rapid tool to discriminate human pathogenic bacterial isolates especially at intraspecific level. This molecular biological technique relies on the use of random oligonucleotide primers that arbitrarily amplifies specific regions of the genome which gives rise to a unique genomic fingerprint of the strains under investigations. With continued development of novel molecular-based technologies for rapid, high-throughput detection of food borne pathogenic bacteria, the future of conventional microbiological methods such as viable cell enumeration, selective isolation of bacteria on commercial media, and immunoassays seems tenuous. Approaches that enhance recovery of sub lethally injured bacteria, differentiation among species, differentiation among bacteria of interest using biochemical profiling, enumeration using impedance technology, techniques to confirm the presence of target pathogens using immunological methods, and bioluminescence applications for hygiene monitoring are of utmost need in identifying and combating the human pathogenic isolates. The aim of this study is to estimate the efficiency of RAPD-PCR technique in assessing the genetic diversity of diseases causing bacterial isolates. The use of RAPD-PCR in evaluating the genomic variability among the pathogenic strains belonging to different genus are also been discussed in the present report.
Presence of specific IgM, IgG and IgA antibodies against Chlamydia pneumoniae was evaluated in children aged 1 week to 36 months to investigate the role of C. pneumoniae in respiratory infections and other diseases. Serum samples were obtained from 150 hospitalized children, including 123 children presenting the clinical symptoms of various respiratory tract infections, two children with acute diarrhoea, two children with meningitis, 14 children with urinary tract infection, and 9 children with non-infectious diseases. Levels of specific C. pneumoniae IgM, IgG and IgA serum antibodies were measured by enzyme-linked immunoassay (ELISA). C. pneumoniae IgM antibodies were detected in 16 (13.0 %) of 123 children with respiratory tract infections. Specific IgG antibodies were found in sera of 11 children under 12 months old. Among 27 children without symptoms of a respiratory tract disease, specific C. pneumoniae IgM were found in two (7.4%) children, including one child with meningitis and another child with urinary tract infection. Specific IgA antibodies were not found in any tested child. All cases of C. pneumoniae infections were identified within two calendar years out of eight that were analyzed, i.e. in 1997 and 2000. The incidence of C. pneumoniae infections varied seasonally, with most children infected in autumn. C. pneumoniae IgM antibodies were detected more often in girls (17.9%) then in boys (7.2%). C. pneumoniae infections occur among small children in central Poland. The results of this study indicate that C. pneumoniae may play a role in the etiology of respiratory tract infections in infants and young children.
Listeria monocytogenes, a food-borne intracellular animal and human pathogen, interacts with infected host cells both prior to entry and during the intracellular phase of infection. This review is focused on the role of secreted proteins including listeriolysin O and two distinct phospholipases C, in modulating the signal transduction of infected cells.
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