Medycyna doswiadczalna i mikrobiologia最新文献

Human digestive system is colonized by a large number of bacteria, estimated to 10(6) - 10(12) per one gram. Those bacteria through a network of interactions and interdependencies, are integrated superorganism. The intestinal flora is a very important element in host's defense against infections of the gastrointestinal tract, caused by for example Salmonella. Therefore, this bacteria have evolved a number of mechanisms, which adapt pathogen to the conditions of the gastrointestinal tract, and on the other hand to the change this environment, for easier colonization and internalization into host cells. One of elements of mentioned above interactions are antimicrobial peptides produced by host's Paneths cells, which have antimicrobial feature. Salmonella mostly are resistant for those peptides, moreover they can stimulate AMPs production for increasing their abilities in competition for ecological niche. In case of Salmonella quorum sensing mechanism was also identified. It allows for recognition of other bacteria presence, which stimulate Salmonella for higher expression of SPI-1, SPI-4 genes. These genes encoded proteins are involved in many host-pathogens interaction, inter alia inflammatory induction. Using of antibiotics in case of Salmonella infections always cause dramatic changes in intestinal flora compositions, which facilitate Salmonella internalizations to host's cells and sometimes could even stimulate to this process. Antibiotic treatment could also cause increase of antimicrobial resistance. Also antibiotics influence on Salmonella carriage was confirmed. Moreover antibiotics could cause super-shedder phenotype, what was detected on streptomycin-treated mice with Salmonella carriage.

Introduction: The aac(6')-Ib-cr gene encodes a variant of aminoglycoside acetyltransferase that confers reduced susceptibility to hydrophilic fluoroquinolones such as ciprofloxacin and norfloxacin. AAC(6')-Ib-cr has two amino acid changes, Trp 102Arg and Asp179Tyr, which together are necessery and sufficient for the enzyme's ability to reduce the activity of fluoroquinolones, including ciprofloxacin and norfloxacin. The aim of this study was to evaluate the prevelance of aac(6')-Ib-cr determinant among 15 Enterobacteriaceae isolates randomly chosen from 215 fluorochinolone resistant strains recovered during the 6 months of 2010.

Methods: The aac(6')-Ib was detected by PCR. The presence of aac(6')-Ib-cr gene variant was futher identified by digestion with BseGI (BtsCI) and sequencing.

Results: 11/15 of the resistant (MIC CIP 2-1024 microg/ml) Enterobacteriaceae strains carried aac(6')-Ib-cr variant.

Conclusion: This is the first study identifying the variant of aminoglycoside acetyltransferase determinant in Poland. Our results demonstrate that this enzym may be even more widespread than Qnr determinants among fluoroquinolone resistant Enterobacteriaceae in Poland.

Introduction: Staphylococcus aureus is a leading cause of bloodstream infections. For epidemiological investigations of this bacteria spa genotyping is used as the method which has a high discriminatory power and gives results that can be easily compared between laboratories. In contrast to methicillin-resistant S.aureus (MRSA), relatively little is known about spa types among methicillin-susceptible strains (MSSA). We used spa typing and antibiotic resistance patterns analysis for retrospective study of S.aureus bloodstream isolates population from the University Clinical Centre (UCC) in Gdańsk.

Methods: The study was performed on 53 isolates from patients of 19 different units/ departments of the UCC. The isolates were tested for the susceptibility to antimicrobial agents. Spa typing was performed on the basis of the sequence analysis of the polymorphic X region of the protein A gene (spa) amplified form the isolates. Spa types were determined by Ridom Staph Type software and were clustered into spa-CCs (clonal complexes) using the algorithm BURP-based upon repeat pattern. MLST (Multilocus Sequence Typing) clonal complexes were predicted from BURP analysis by the Ridom SpaServer database. In MRSA the staphylococcal chromosomal casette (SCC) mec was determined,

Results: Spa-typing yielded 26 types. Six spa-CC and seven singletons were identified. The most frequent was spa-CC021involving 38% of isolates. The CC021 consisted of 7 spa types and the most common was t021 corresponding with MLST-CC30. The second frequent was singleton, related to MLST-CC1, with only one type t127. There were 3 MRSA isolates in the population. The MRSA strains were identified as different spa types: t003/ SCCmecII, t008/SCCmecIV and clonally related to MSSA t032/SCCmecIV. No one MRSA strains belonged to spa-CC021.

Conclusions: The spa clonal cluster corresponding with widely distributed among invasive S.aureus strains in Europe MLST-CC30 was found as the most frequent among S.aureus bloodstream isolates from the UCC. Occurrence of spa types which had a genetic background common to well known MRSA clonal lineages was observed.

Introduction: Coagulase-negative staphylococci (CNS), particularly Staphylococcus epidermidis and Staphylococcus haemolyticus, are the leading cause of infection among infants with very low birth weight (<1500 g). The most important virulence factor of these pathogens is their ability to form biofilm. The aim of this study was to evaluate the surface properties, the ability to produce slime and biofilm formation of S. epidermidis and S. haemolyticus strains isolated from infections in very low birth weight neonates.

Methods: Isolates ofS. epidermidis (n=60) and S. haemolyticus (n=38) were obtained from neonates, hospitalized in two neonatal intensive care units in Poland. Cell surface hydrophobicity was determined by autoagglutination test (AA) in 0.9% NaCl and salt aggregation test (SAT) in ammonium sulphate solution. In order to determine the ability to produce slime, Christiensen's tube test with safranin staining and Congo Red Agar (CRA) test were carried out. The quantitative assessment of biofilm production was determined by crystal violet (CV) assay.

Results: Based on the AA test, it was demonstrated that almost all S. epidermidis and S. haemolyticus isolates showed no agglutination in sodium chloride saline. The SAT test indicated that the greatest number ofS. epidermidis isolates aggregated in concentration of 2 M, whereas, for S. haemolyticus, it was 0.5 M. In the Christiensen's method, the largest amount of the S. epidermidis isolates produced a small amount of slime (40%), whereas 68% of the S. haemolyticus isolates produced a large amount of slime. In CRA test, in both species, the most common result was the bacterial culture colour being almost black, which corresponds to low production of biofilm. Quantitative assessment of biofilm production in CV assay revealed that while 97% of the S. heamolyticus isolates produced high levels of biofilm, similar results were observed in only 43% of the S. epidermidis isolates.

Conclusions: Based on the results obtained by phenotypic methods, it was demonstrated that the S. haemolyticus isolates showed a statistically significant stronger ability to produce mucus and form biofilm than the isolates ofS. epidermidis.

Introduction: A variety of viruses and bacteria are responsible for acute upper and lower respiratory tract infections worldwide. Severe and even fatal disease can occur especially in group ofimmunocompromised individuals. Accurate pathogen identification allows clinicians to determine the need for ancillary diagnostic testing, antibacterial and/or antiviral therapy and can motivate decisions regarding hospitalization and infection control measures.

Methods: We compared the diagnostic performance of FilmArray Respiratory Panel highly multiplexed nucleic acid amplification test with previous used direct immunofluorescence assay. Both assays were performed on a panel of 6 nasopharyngeal-secretion specimens and 6 BALF samples, collected from 12 patients, subjected to allogeneic haematological stem cells transplantation, with lower respiratory tract symptoms.

Results and conclusions: Among viruses detectable by both assays were especially influenzaA virus, parainfluenza viruses type 3 and respiratory syncytial virus. In conclusion, the FilmArray assay is rapid and extremely user-friendly system, with results available in just over one hour with almost no labor involved. In few laboratories its low throughput and qualitative results may be a disadvantage in some clinical settings.

Unlabelled: INDRODUCTION: Recent years have brought reports about increasing role of the viruses among the pathogens causing gastro-intestinal acute infections. Among them norovirus and rotavirus dominate. Rotavirus infections are the major reason of nosocomial infections in pediatric wards, and norovirus are the most common factors ofepidemiological gastrointestinal infections among adults. The knowledge about epidemiology of nosocomial diarrheas and microbiological characteristics of mentioned viruses is very useful in the process of prevention of spreading infections. The aim of the study was the laboratory diagnostics of etiology factors inducing intestinal infections of hospitalized patients as well as the evaluation of hospital epidemiological situation in terms of gastro-intestinal infections caused by viruses in the year 2011.

Methods: Pathogen causing infections was determined on the basis of results of stool samples analysis. Samples were collected from patients with infection's symptoms. The process of rotaviruses diagnosis was using single-stage membrane test based on immunochromathographic technology, by STAMAR. Norovirus infections were detected by immunoenzymatic third-generation qualitative test "Norovirus RIDASCREEN" by R-Biopharm. Analysis of gastrointestinal infections caused by norovirus and rotavirus was carried out on the basis of diagnostic tests results of infected patients and data from the infection registry of hospital epidemiological surveillance in the year 2011. Reported infections of rotavirus or norovirus were analyzed with regard to gender of patients, hospital ward, time (month) of occurrence and type of infection (nosocomial or non-nosocomial). The data were statistically analyzed using non-parametrical chi2 test of the statistical package SPSS 12.0PL.

Results: The results showed considerably greater number of rotavirus infections (176 cases - 0.87% of hospitalized patients) than norovirus infections (118 cases - 0.58% of hospitalized). Majority of rotavirus infections (96.6%) applied to pediatric ward patients, their occurrence indicated seasonality of this infections. All of norovirus infections were classified as nosocomial.

Conclusions: Following hospital dyscypline increases safety of hospitalized patients and reduction of epidemiological focuses, what was confirmed by relatively low rate of patients diagnosed with defined nosocomial infections.

Introduction: The ability of growth of Acinetobacter baumannii as morphology colony variants have been observed. However, the importance of this phenomenon for its biology is not known. The aim of this study was to evaluate some properties of light and dark morphology colony variants.

Methods: Fifty two isolates were identified by MALDI TOF MS method (MALDI Biotyper, BRUKER). It was evaluated the adhesion to polystyrene and extracellular mucus production of morphology colony variants and its susceptibility to imipenem and meropenem by agar dilution method.

Results: Forty eight (92.3%) out of the 52 morphotypes Acinetobacter sp. were identified as A. baumannii, two (5.8%) as A. genomospecies 3, one as the A. calcoaceticus. Sixteen (61.0%) pairs of isolates showed differences in the similarity of the spectra to the spectra of reference strains in the MALDI-TOF MS method. Adhesion to polystyrene was observed in all dark and 92.3% light morphotypes. Extracellular slime was produced by 15 (57.7%) dark morphotypes, and 7 (26.9%) of clear. The differences in susceptibility to imipenem occurred in two (7.7%), and meropenem in three (11.5%) pairs of morphotypes.

Conclusions: The results show diversity of biological properties of morphology colony variants of A. baumannii complex. Differences in the level of adhesion to polystyrene and slime production may indicate the importance of morphological differentiation in virulence of A. baumannii complex.

Introduction: According to WHO reports, there are 130-170 million persons chronically infected with hepatitis C virus on a global scale. There is no effective vaccine against HCV, and the current standard of chronic hepatitis C therapy has limited efficiency and undesirable side effects. Current studies are focused on searching for a new therapeutic agents, which are specifically targeted against the virus. The aim of the study was to develop a methodology for testing the activity and cytotoxicity of potential helicase inhibitors (derivatives of anthracycline antibiotics) in Huh-7.5 cell line infected with HCV.

Methods: The Huh-7.5 cell line was infected with the JFH1 (Japanese Fulminant Hepatitis) RNA by lipofection. The cytotoxicity of anthracycline antibiotics was measured by Cell Proliferation Kit II(XTT), after 1, 2, 3, 4 and 24 hours after incubation with tetrazolium salt XTT. The activity ofanthracycline antibiotics was examined by Real-Time PCR method.

Results: The study allowed to optimize the conditions of cytotoxicity and activity studies of anthracycline antibiotics.

Conclusions: Huh-7.5 cell line infected with HCV is a robust cell culture model for screening new antivirals against HCV.

Introduction: Dental caries is a bacterial disease. The most important element used in caries prevention is fluoride, which is derived from the air, diet or fluoride-containing preparations and materials, e.g. glass-ionomer restorations. Modern fluoride-containing restorative materials are capable of releasing fluoride to the environment. Fluoride can be also accumulated in glass-ionomer cements, thus an attempt was made to saturate these materials with fluoride. The aim of the study was to evaluate the effect of topical fluoridation of Ketac Molar Aplicap glass-ionomer cement on the growth of Lactobacillus spp. in the dental plaque.

Methods: The study was carried out in 15 patients with good oral hygiene, in whom 35 fillings with conventional glass-ionomer material, Ketac Molar Aplicap, were performed. After 6 months, three-day dental plaque from these fillings was examined. Next, fluoride was rubbed on the glass-ionomer surface and the examination of three-day dental plaque was repeated.

Results: No statistically significant differences (p = 0.143) in the amounts of Lactobacillus spp. in the plaque collected prior to and after topical fluoridation were revealed.

Conclusions: Fluoride rubbed in the conventional glass-ionomer cement, Ketac Molar Aplicap, did not affect the amount of Lactobacillus spp. in the dental plaque growing on this material.

Introduction: The study evaluated the cell wall carbohydrates fraction in blastoconidia grown in YEPD medium at 30 degrees C and in the conglomerate of true hyphae grown in human serum at 37 degrees C.

Material and methods: The clinical isolate obtained from a child with widespread C. albicans infection was used in the study. The cells were broken with glass beads, centrifuged to harvest the cell wall followed by subjection to TFA hydrolysis and in the result of that released monosaccharides were detected by HPAEC-PAD. Both, serum and temperature conditions (37 degrees C) affected germination process influencing the cell wall carbohydrates content when incubation in serum was prolonged from 1 to 18 h.

Results: The mannan content of blastoconidia was almost twofold higher compared to filamentous forms (149.25 +/- 299.24 vs 77.26 +/- 122.07). The glucan content was threefold lower in blastoconidia compared to hyphae (251.86 +/- 243.44 vs 755.81 +/- 1299.30). The chitin level was fourfold lower in blastoconidia compared to filaments (23.86 +/- 54.09 vs 106.29 +/- 170.12). The reason for the differences in the carbohydrates content may be related to type of morphology induced in different environmental conditions. Among tested carbohydrates, glucan appeared to be present in appreciably larger amounts in both tested morphological fractions. The ultrastructure of the blastoconidial cell wall revealed striking differences compared to the hyphae indicating the carbohydrates content alterations for wall assembly during hyphal growth at alkaline pH and temp. 37 degrees C.

Conclusions: The study provided evidence for the relationship between morphogenesis, cell-cell adhesion induced by serum and changes in the level of carbohydrates content.