Medycyna doswiadczalna i mikrobiologia最新文献

Introduction: The aim of this study was evaluation of molecular identification results of samples including genomic DNA of Bordetella by using PCR method, obtained by laboratory of Department of Bacteriology NIZP-PZH and their comparison with the results obtained by other reference laboratories in EU. The study was conducted within the framework of the first external quality assessment (Eupert-labnet Bordetella PCR EQA).

Methods: The panel of ten coded samples of purified genomic DNA was investigated. The panel was designed to include dilution of genomic DNA from B. pertussis at the three concentrations 2 pg/microl (high), 0,2 pg/microl (medium) and 0,02 pg/microl (low). The panel included as well DNA of other Bordetella species (B. parapertussis, B. holmesii, B. bronchiseptica) and H. influenzae at concentrations 2 pg/microl. There was also two ,,blank" samples containing only Tris Buffet (10mM, pH 8,0). Presence or absence of B. pertussis DNA in the tested samples was determined by using four PCR assays: conventional in-house PCR (detection of IS481 B. pertussis and IS1001 B. parapertussis), commercial multiplex PCR (detection of DNA B. pertussis), conventional in-hause real-time PCR (detection of IS481 B. pertussis) and commercial real-time PCR (detection of IS1001 B. parapertussis).

Results: All but one samples were correctly identified in our laboratory. Laboratory of Department of Bacteriology NIZP-PZH correctly detected DNA ofB. pertussis at both the ,,high" and ,,medium" dilution. In addition, the distinction between B. pertussis and other Bordetella species was correctly obtained by our laboratory. The negative samples, the two blank samples and one containing H. influenzae were correctly detected.

Conclusions: Results of the first international external quality assessment have confirmed competences of laboratory of Department of Bacteriology NIZP-PZH in molecular identification of Bordetella pertussis.

Introduction: Little is known about the involvement of hydrolytic enzymes such as lipases as virulence factors in infections involving Enterococcus spp.

Methods: A total of 45 isolates of E. faecium were investigated. Lipolytic activity of enterococcal strains was determined by Tryptic Soy Agar containing Tween 20, Tween 40, Tween 60, Tween 80 and egg yolk.

Results: We detected that E. fecium strains produced lipases more frequently on Tween 20 agar (71.1% strains) than on Tween 40 agar, Tween 60 agar, Tween 80 agar, egg yolk agar (respectively 33.3%, 24.4%, 20.0%, 31.1%). Our results indicate that lipase may be a virulence factor in E. faecium.

Conclusions: Studies suggest that source of isolation from clinical materials (blood, wound and fluid from the abdominal cavity) does not have an influence on the ability hydrolysis esters.

Introduction: Antimicrobial properties of silver nanoparticles (SNP's) have been recentl well evaluated, and now are being considered as excellent candidates for therapeutic purposes. It is confirmed, that various solutions of colloidal SNP's possess significant antibacterial properties against such species as: Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa even at low concentrations, although there have been so far only a few researches evaluating antimicrobial activity of SNP's against cariogenic bacteria: Streptococcus mutans, Streptococcus salivarius and Streptococcus mitis responsible for initiation of dental carries. Tooth decay is infectious disease an worldwide, which may occur in patients of every age. Nanotechnology creates a new approach of designing of medical devices preventing or reducing bacterial colonization.

Methods: Colloidal silver solution (CSS) of concentration 350 ppm was used in this research. Nanoparticles size, shape and solution stability were evaluated. 16 strains of cariogenic bacteria, 4 isolates of each species: S. mutans, S. salivarius, S. sanguinis and S, mitis were obtained from plaque swabs of 7 patients treated for dental carries at Department of Conservative Dentistry, Medical University of Warsaw. MIC and MBC values for CSS's were evaluated.

Results: CSS used in this research is of good stability. No agglomeration or coalescence was observed during 24 hours of experiment. Silver nanoparticles were of round shape and had mean size of 67 nm. MIC values were: 12-25 ppm for S. salivarius, 25 ppm for S. sanguinis, 50-100 ppm for S. mitis and 50 ppm for S. mutans, while MBC values after 1 hour of bacterial contact with nanoparticles were 200-350 ppm for all cariogenic bacterial species. After 24 hours of contact MBC values were: 25-50 ppm for S. salivarius and S. sanguinis, 100-200 ppm for S. mitis and 200 ppmfor S. mutans.

Conclusions: Antimicrobial properties of CSS depend on nanoparticles concentration and interaction time with bacteria. The susceptibility of cariogenic oral streptococci to silver nanoparticles is diversified. Sufficient concentration which inhibited all cariogenic bacteria in our research was 200 ppm after long (24 hours) period of silver nanoparticles interaction with bacteria.

Introduction: The high-pathogenicity Y. enterocolitica bioserotype 1B/O8 has been isolated from human clinical samples since 2004 year in Poland. The group of "American" strains of Y. enterocolitica is considered to be the second, major causative agent ofyersiniosis in Poland, after the predominant bioserotype 4/O3. The high-pathogenicity of Y. enterocolitica 1B/O8 is likely attributed to the presence of a couple of chromosomally encoded virulence factors including yersiniabactin (Ybt). The aim of the present study was to examine the occurrence of known virulence factors in human clinical isolates of Yersinia enterocolitica bioserotype 18/08, isolated in Poland.

Methods: The group of 64 isolates of Y. enterocolitica bioserotype 1B/O8, isolated from clinical specimens in Poland in 2009 year was examined for the presence of the selected virulence determinants by multiplex-PCR.

Results: All of the tested Y. enterocolitica 1B/O8 isolates have the same virulotype (ail+, ystA+, myfA+, myfB+, myfC+ irp1+, irp2+, fuyA+, yst1+ chiY+, ysrS+), specific for the high--pathogenicity American strains of Y. enterocolitica.

Conclusions: Presence of the genes encoding yersiniabactin (irp1+, irp2+, fuyA+), chromosomal secretion system Ysa (chiY+, ysrS+) and Yst1 (yst1+) may argue for the extended pathogenic potential of the Y. enterocolitica bioserotype 1B/O8 in Poland.

Introduction: The optimization of quality testing strategy of products containing probiotics might allow to general improvement of its safer use in humans. The goal of the study was the evaluation of quality expressed by identity, colony forming unit (CFU) and antibiotic sensitivity ofprobiotics used in medicinal products available in Poland using the appropriate and validated procedures.

Methods: The medicinal products containing L. rhamnosus, L. acidophilus, L. delbrueckii subsp. bulgaricus and B. animalis subsp. lactis, L. helveticus, and L. gasseri were tested for species identity performed with validated rep-PCR (BOXA 1R) method. The antimicrobial susceptibility of working seeds and strains isolated to 26 antibiotics were tested by disk diffusion and E-test methods using relevant references as recommended by EUCAST. The numbers of probiotic strains, expressed as cfu count per package, was done using plating plunge method.

Results: All strains tested, except B. lactis, were found to be resistant to trimethoprim-sulphamethoxazole, nalidixic acid, metronidazole, and colistin. B. lactis was resistant to aminoglycosides. L. rhamnosus strains were found to be resistant to vancomycin, (MIC > 256 microg/ml) similarly to ATCC strains (L. rhamnosus GG 53103 and 244). The sensitivity to other antibiotics was strain specific. The rep-PCR method was found species and strain specific. All products tested fulfilled declared countent as measured by cfu count/package.

Conclusions: Quality of medicinal products containing probiotics was found undoubted and confirmed. The optimized strategy of quality monitoring of probiotics used in medicinal products can be used in dietary supplements and foodstuffs intended for particular nutritional uses.

Introduction: In recent years an alarming increase of carbapenem-resistant Enterobacteriaceae has been noticed, which creates frequent therapeutic problems, especially for patients residing in intensive care units (ICU). The aim of this study was to evaluate the prevalence of carbapenem-resistant strains of Enterobacteriaceae isolated in the years 2006-2011 at the University Hospital in Bialystok (UHB).

Methods: Based on microbiological analysis reports we conducted a retrospective study of strains resistant to carbapenems. We assigned strains to three carbapenem-resistance phenotypes, and analyzed susceptibility to antibiotics and prevalence of these strains in hospital wards and in clinical specimens collected from hospitalized patients. During a six-year period, 216 strains resistant to carbapenems were tested, which represents 0.96% of all Enterobacteriaceae (n = 22.391) isolated during this period.

Results: The greatest number of carbapenem-resistant strains was identified in 2011 (96 strains, 44.44%). Antibiotics that showed the highest activity against strains occurring most frequently (Klebsiella pneumoniae [n = 103] and Enterobacter cloacae [n = 85]) were tigecycline (102 [99.03%] of K. pneumoniae tested strains and 61 [100%] of E. cloacae strains were susceptible), colistin (33 [86.84%] of K. pneumoniae tested strains and 84 [100%] of E. cloacae were susceptible), and amikacin (86 [83.49%] of K. pneumoniae tested strains and 26 [30.58%] of E. cloacae strains were susceptible).

Conclusions: Carbapenem resistance among Enterobacteriaceae isolates showed a trend to increase during the six-year period of study. Because infections caused by carbapenem-resistant strains are frequently life-threatening, the effective strategies to control the spreading of antibiotic resistance are necessary.

The causative agent of tetanus is the obligate anaerobic bacterium--Clostridium tetani. These bacteria form endospores that are able to survive long periods of exposure to air and other adverse environmental conditions. Infection generally occurs through wound contamination. We can distinguish several forms of tetanus: generalized, local and neonatal. Diagnosis of tetanus is based primarily on the patient's clinical symptoms (muscle cramps, painful back muscle spasms, generalized contractions of the arcuate curvature of the body) as well as on microbiological diagnosis. This article is a brief review of C. tetani and diagnosis of infections caused by these organisms in humans.

Introduction: The intranasal immunization is considered the effective method to induce immunological response in the mucosa and the model useful to develop the vaccine against otitis media due to nontypaeble Haemophilus influenzae infections. In the study, elimination of NTHi strains isolated from healthy and carrier individuals, varying with several genetic determinants, from mice nasopharynx, lungs and ears tissues and the interactions among strains during mixed infections were evaluated.

Methods: Mice were infected with single and mixture of NTHi strains previously identified as non or potentially invasive. The curves of infections were drown from the averages of log cfu/mg values obtained for nasopharynx or ears leavages or lungs homogenates coupled with standard deviation at each time point using 5 mice. The significance of the differences was confirmed using ANOVA method.

Results: The course of infections induced with a single noninvasive or potentially invasive strains in the mice nasopharynx, ear or lung tissues were not found to differ in respect to the level and duration. Regardless the strain used, higher elimination rates in the ear and lung tissues in comparison with nasopharynx were fund. Different rate of elimination was found in the case of mixture infections where the strain, determined in the previous study as potentially invasive, was dominating.

Conclusion: The concurrence model among not-invasive and potentially invasive NTHi strains in the host niche was thus confirmed using in vivo model of infection.

Introduction: One of the most serious complications associated with the use of implants in hernia surgery is deep surgical site infection involving an implanted biomaterial. Among the major etiological factors of this complication are Staphylococcus aureus and Escherichia coli strains, which have the ability to form a biofilm on the surface of the mesh implant. This process is influenced by many factors, of which, according to current medical knowledge, the concentration of glucose may have a clinical significance. The aim of the presented study was to evaluate the effect of glucose on the formation of biofilm on the surface of monofilament polypropylene mesh.

Methods: The study included 140 bacterial strains (70 S. aureus and 70 E. coli) from the collection of Department of Microbiology Collegium Medicum im. L. Rydygier in Bydgoszcz, Nicolaus Copernicus University in Torun. Evaluation of the effect of two glucose concentrations (0.1% and 0.2%) on biofilm formation was performed using a qualitative (2,3,5-triphenyltetrazolium chloride reduction) and a quantitative ( serial 10-fold dilutions) methods.

Results: A qualitative analysis, performed after a period of incubation on substrates containing various concentrations of glucose, has revealed a statistically significant increase in the percentage of S. aureus strains with a very high potential for biofilm formation, while for E. coli an increase was observed in the percentage of strains with a low potential for biofilm formation. In a quantitative analysis of the biofilm of S. aureus forming after incubation on a substrate containing 0.1% and 0.2% glucose, significantly more colony forming units (CFUs) were isolated per one milliliter of the suspension (CFU/ml) than in the control group biofilm samples. On the other hand, the biofilm created by E. coli after a period of incubation on a substrate containing 0.2% glucose yielded significantly fewer CFUs per one milliliter than from the biofilm resulting from incubation on substrate with 0.1% glucose or the control group. No statistically significant difference was found between the numbers of CFUs per one milliliter isolated from E. coli strains after incubation on a substrate with 0.1% glucose and the control group.

Conclusions: At concentrations of 0.1% and 0.2%, glucose increases biofilm formation by S. aureus strains on the surface of monofilament polypropylene mesh; at 0.2% glucose limits biofilm formation in E. coli.

Introduction: The widespread use of antiseptics for wound dressings, unfortunately, not always effective, prompted us to search for alternative solutions, tailored to individual patient's needs. The aim of the study was checking the validity of the idea to apply some selected essential oils in order to modify active dressings which are routinely used in the care of chronically infected wounds. Our choice is commercially available an absorptive wound dressing which does not contain antiseptics (Sorbact).

Methods: The proposed is modification of dressing by its immersion in essential oil solution and then estimation of the biocide availability and stability during storage. Evaluation of inhibition of microbial surface growth (zone inhibition) and survival of absorbed microorganisms (retentivity by CFU counting) was performed directly after modification and repeated after 7 days of their storage at 4 degrees C.

Results: This study indicated that the dressings containing essential oils can keep absorbed bacteria/fungi inside and efficiently limit their growth. Depending on the properties (composition of volatile fraction) of the tested essential oil, saturated dressings were more active when stored at 4 degrees C for 7 days after their modification. The differences of antimicrobial strength, duration of the effect and retentivity between essential oils used for dressing modification have been shown.

Conclusions: Modification of absorbent dressings with essential oils is a good option to achieve better therapeutic effect. Using a mixture of these four essential in several different quantitative ratios can be considered and is worthy of further research.