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M Kolár

Publications and source records attributed to M Kolár.

At least 19 recordsLinked to original sources
PubMed2006

Some aspects of physico-chemical properties of TiO2 nanocolloids with respect to their age, size, and structure.

Aqueous colloidal solutions of quantum sized particles of titanium dioxide (Q-TiO2) undergo an aging process since the moment of their preparation. In course of time, the mean size of nanoparticles is gradually increasing and some of their physicochemical properties are changing as well. In the present study, the decrease of the blue spectral shift of the semiconductor absorption threshold was measured to determine the corresponding changes of band gap energy of the Q-TiO2 particles. In parallel, the decrease of the specific surface area of these particles was followed through their complexation with 2-coumaric acid. The formation kinetics and thermodynamic equilibrium of these surface charge-transfer complexes were investigated in detail by means of UV/vis absorption spectroscopy. Besides, the size and shape of the Q-TiO2 particles aged 2, 4, and 10 years were compared employing direct observation by means of high resolution transmission electron microscopy. On the basis of real particle images, a model of nanocrystalline anatase was developed. The specific surface areas estimated through complexation with 2-coumaric acid were confronted with the numbers of appropriate titanium atoms located on the particle surface that were calculated from a model of anatase nanocrystals of different sizes. The photocatalytic activity, which represents the most important quality of anatase from practical point of view, was repeatedly determined through photocatalytic degradation of 4-chlorophenol in a colloidal solution of Q-TiO2 particles during its aging at 4 degrees C for three years. The corresponding reaction rate was increasing rapidly in the first weeks; it almost tripled in 68 days, and afterward it approached a limiting value. On the whole, the initial value increased four times in three years. Voltammetry at hanging mercury drop as the last method for aging description did not show any significant change of voltammetric behavior in a short two months period. However, while compared to preceding results of a similar TiO2 system, new redox processes of Q-TiO2 colloids were observed in the negative potential range. Besides the reduction of surface protons reported previously, two new pairs of peaks appeared.

Journal Article↗
PubMed2006

[Molecular diagnostics for the detection of prosthetic joint infection].

PURPOSE OF THE STUDY: Ten years after inauguration of the molecular methods into the orthopaedic practice for diagnosing Prosthetic Joint Infection (PJI), this approach is still in the limelight of research and discussion. The aim of the current study was to determine the diagnostic power of our Polymerase Chain Reaction (PCR) protocol for preoperative detection of bacterial nucleic acid in the synovial joint fluid. MATERIAL AND METHODS: Synovial fluids obtained from thirty-five septic hip or knee arthroplasties and sixty-six aseptic controls were investigated by the conventional PCR technique. Two subgroups were established with regard to antibiotic administration before sample collection; with (n=13) and without (n=22) previous antibiotic exposition, respectively. All the surgeries were performed under the identical conditions with strictly established and fulfilled inclusion criteria. The study design applied was a prospective cohort trial. Primers targeting phylogenetically conserved regions of the bacterial gene were used to detect the bacterial 16SrRNA gene in the retrieved samples. If this was positive, a restriction endonuclease treatment of the amplified DNA was performed to reveal the PJI pathogen. Current guidelines were used to evaluate the test performance, including the confidence intervals. The concordance between the culture and PCR identification of PJI pathogens was estimated providing both of the relevant data were available. RESULTS: A qualitative analysis showed the following figures in the subgroup without previous antibiotic exposition: sensitivity (0.64), specificity (0.97), accuracy (0.89), positive predictive value (0.88), negative predictive value (0.89), likelihood ratio for positive result (21.0), and likelihood ratio for negative result (0.38). In the second subgroup the corresponding figures were as follows: 0.85, 0.97, 0.95, 0.85, 0.97, 27.9, and 0.16. The rate of concordance between the microbial and PCR findings was almost identical in both of the subgroups. DISCUSSION: There were large discrepancies in sensitivity and positive predictive values found in the published results. The earlier studies have had various methodological weaknesses, including a lack of strictly formulated inclusion criteria and control groups. In addition, there are differences among research centers in PCR laboratory procedures and specimen retrieval tactics which may potentially have an impact on PCR results. Low sensitivity and high specificity of our PCR technique may be explained by both the intrinsic (DNA extraction protocol, configuration of inner controls, choice of detection threshold, etc.) and extrinsic factors (in particular intra-operative retrieval of specimens). A hypothesis on the inadequacy of PCR techniques for PJI detection still remains to be excluded. CONCLUSION: Based on the current study, the positive results of our PCR technique may be perceived as a mild criterion from the point of power for PJI diagnosis support. However, its clinical utility should be significantly increased in cases with higher pretest probability of PJI, but negative cultures.

Adult↗
PubMed2004

Double-disk synergy test positivity in Stenotrophomonas maltophilia clinical strains.

The double-disk synergy test (DDST) using Mueller-Hinton agar and antibiotic disks with centrally positioned disks of amoxicillin-clavulanate, ampicillin-sulbactam, and piperacillin-tazobactam and, at a center-to-center distance of 25-30 mm, 2-4 disks with 10 various beta-lactam antibiotics per one plate was performed in 58 clinical isolates of Stenotrophomonas maltophilia to determine the effectivity of 3 beta-lactamase inhibitors. When tested with clavulanate as the central beta-lactamase inhibitor synergic action on tested strains was the most frequent with aztreonam (81.0% of strains), cefoperazone (63.8%), and cefepime (60.3%). With sulbactam the synergic action, i.e. DDST positivity, was high in the case of cefoperazone (15.5%), ampicillin, aztreonam and piperacillin (8.6% each); with tazobactam it was the most frequent with aztreonam (53.4%), cefoperazone (44.8%) and cefepime (37.9%). No synergy was demonstrated after application of meropenem regardless of the kind of beta-lactamase inhibitor used. In 58 strains of S. maltophilia, 55 different profiles of DDST positivity were found. The results confirm that clavulanate is the most effective inhibitor of S. maltophilia beta-lactamases. The utilization of DDST (performed in the recommended way) for the typization of strains Stenotrophomonas species and for the estimation of potential effectiveness combinations of beta-lactams with beta-lactamase inhibitors for the therapy of stenotrophomonade infections was suggested.

Amoxicillin-Potassium Clavulanate Combination↗
PubMed2001

Occurrence of variants with temperature-dependent susceptibility (TDS) to antibiotics among Stenotrophomonas maltophilia clinical strains.

Susceptibility to 20 antibiotics was tested in 104 Stenotrophomonas maltophilia strains at 37 and 30 degrees C by means of a dilution micromethod to verify the phenomenon of temperature-dependent susceptibility (TDS). Trimethoprim-sulfamethoxazole, pefloxacin and ofloxacin were the most active preparations at 37 degrees C (93, 90, and 86% of susceptible strains, respectively), whilst trimethoprim-sulfamethoxazole, cefoperazone-sulbactam and pefloxacin performed best at 30 degrees C (94, 94, and 76% of susceptible strains, respectively). Variants 37TDS (minimum inhibitory concentration, MIC, of tested antibiotics at least 4-times lower at 37 than at 30 degrees C) occurred in 60%. Variants 30TDS (at least 4-times lower value of MIC at 30 than at 37 degrees C) were found in 7.7%. Both variants in susceptibility to tested antibiotics appeared in 23.1%, whilst neither of them was observed in 9.6%. The 37TDS phenomenon was recorded most of all with gentamicin (51% of strains), amikacin (47), colistin (44) and tetracycline (34). The 30TDS phenomenon was found particularly with cefoperazone-sulbactam (16.0% of strains) and colistin (10.0%). The above phenomena may be due to changes in membrane permeability, temperature-dependent ribosomal changes, and insufficient adaptation to higher temperatures of some strains of the originally environmental species S. maltophilia.

Anti-Bacterial Agents↗
PubMed2001

Antibiotic selective pressure and development of bacterial resistance.

This study evaluates the development of resistance in Gram-negative rods to cefotaxime and ceftazidime, ofloxacin and ciprofloxacin, gentamicin and amikacin, meropenem and ampicillin/sulbactam over a five year period of use (1994-1998) at the University Hospital in Olomouc, Czech Republic. The development of bacterial resistance was linked with antibiotic use and hence selective pressure which was specific for the type of antibiotic and the bacterial species. Statistically significant correlations were found for the use of ofloxacin and resistance in Escherichia coli, Proteus vulgaris and Providencia rettgeri; cefotaxime and Enterobacter cloacae; ceftazidime and Acinetobacter spp., Enterobacter agglomerans and Proteus vulgaris; and gentamicin and Proteus mirabilis.

Aminoglycosides↗
PubMed1999

Development of bacterial resistance to the third generation cephalosporins and their clinical use.

Development of Gram-negative rods resistance to the third generation cephalosporins (cefotaxime, ceftazidime, cefoperazone) in connection with their application at the University Hospital in Olomouc was evaluated in this study. The highest increase in resistance to cefotaxime was detected in Enterobacter cloacae (from 22.9% in 1995 to 49.0% in 1997) and Enterobacter agglomerans strains (28.0% - 40.5%). In addition, increased resistance to ceftazidime in Acinetobacter baumannii (12.5% - 35.1%), Enterobacter aerogenes (7.4% - 20.9%), Enterobacter cloacae (16.7% - 47.2%) and Pseudomonas aeruginosa (4.0% - 26.3%) was observed. Finally, the greatest increase in frequency of strains resistant to cefoperazone was observed in E. aerogenes (18.4% - 30.1%), E. agglomerans (31.0% - 52.3%), E. cloacae (35.5% - 47.2%) and Providencia rettgeri (26.5% - 53.2%). A 23.5% increase in third generation cephalosporin use was evident by evaluation of RDDD(ATB) parameters in 1996 and 1997. Corresponding values for individual antibiotics were 26.5% cefotaxime, 20.7% ceftriaxone, and 40.3% ceftazidime increase. However, cefoperazone use decreased by 10.9%.

Cefoperazone↗
PubMed1999

Occurrence of vancomycin-resistant enterococci in relation to the administration of glycopeptide antibiotics.

Occurrence of vancomycin-resistant enterococci and its relationship to the administration of glycopeptide antibiotics (vancomycin, teicoplanin) was described. A total number of 628 strains of the genus Enterococcus was isolated in the Hemato-oncologic Department of the University Hospital in Olomouc in 1997. Seven strains (1.1%) were found to be resistant to vancomycin. Five of them were identified as Enterococcus faecalis of phenotype VanB, and two strains as E. faecium of phenotype VanA. The administration of vancomycin and teicoplanin in the Hemato-oncologic Department amounted to 85.7% and 89.2%, respectively, of the total consumption of these drugs at the University Hospital.

Anti-Bacterial Agents↗
PubMed1999

Characteristics of Acinetobacter strains (phenotype classification, antibiotic susceptibility and production of beta-lactamases) isolated from haemocultures from patients at the Teaching Hospital in Olomouc.

A total of 85 strains of the genus Acinetobacter were isolated from haemocultures at the Institute of Microbiology of the Teaching Hospital in Olomouc over the period January 1993 to June 1997. Sixty-two (73.0%) strains of the Acinetobacter calcoaceticus-baumannii complex (Acb complex) were the most frequent. In 3 (3.5%) strains it was impossible to decide whether they belonged to the Acb complex. Other acinetobacter species were represented by 20 (23.5%) strains. The greatest amount (28.2%) of these strains was collected from the Clinic of Internal Medicine. Leukemias, lymphomas and myelodysplastic syndromes were the most frequent clinical diagnoses (20.0%) of the patients with a positive haemoculture. The most effective antimicrobial preparations tested were as follows: meropenem (98.8% of susceptible strains), colistin (94.1%), quinolones (90.6-94.1% according to the type of agent) and amikacin (91.8%). The Acb complex strains were less susceptible to antimicrobial agents than other acinetobacters. Production of inductive chromosomal beta-lactamases AmpC was proved in 42 (49.4%) strains whilst no occurrence of extended-spectrum beta-lactamases (ESBL) in the isolated organisms was recorded.

Acinetobacter↗
PubMed1999

[Use of sulperazone in acute surgical conditions].

In the period between February 2, 1988 and October 30, 1998, the investigators administered Sulperazon to 20 patients at the Surgery Department 1, University Hospital Olomouc, in whom they expected good clinical effect (i.e., high concentration in bill, effect on respiratory tract pathogens). Sulperazon was administered in 12 cases as a drug of first choice, in 8 cases as a drug of second choice. In all cases, relief from clinical symptoms of infection was observed within 5 days of treatment and in 83% of cases eradication of previously cultivated pathogen was achieved. Sulperazon was well tolerated and no side effects or impoivment of laboratory test were observed. In 4 cases, prolonged administration was complicated by candida superinfection. Sulperazon proved to be effective in surgery in treatment of infectious complications of bile duct and pancreas diseases and in thoracic cavity pathology.

Abdomen↗
PubMed1998

[Bacterial strains isolated from neutropenic patients and their resistance to antibiotics].

BACKGROUND: Although Gram negative as well as Gram positive bacteria participate in febrile episodes of neutropenic patients, in particular recently the ratio of Gram positive bacteria is increasing. The objective of the present work was to investigate the incidence and antibiotic resistance of pathogenic bacterial agents in neutropenic patients. METHODS AND RESULTS: The presence of bacteria was investigated in 446 neutropenic patients hospitalized at the Haematological Clinic in 1995. Haemocultures (apparatus Bact/Alert 120, cultivation media Organon-Teknika) and urine were examined. The sensitivity for antibiotics was tested by the standard dilution micromethod. In blood most frequently Staphylococcus epidermidis was isolated (45.4%), coagulase-negative strains of Staphylococcus haemolyticus, Staphylococcus hominis and Staphylococcus saprophyticus (14.4%), Acinetobacter calcoaceticus-baumannii (complex 6.3%) and Pseudomonas aeruginosa (6.3%). In urine the following were detected: Staphylococcus epidermidis (36.5%), Enterococcus sp. (14.5%), Escherichia coli (13.1%), Enterococcus faecalis (11.6%) and Enterococcus solitarius (6.5%). In all strains resistance to antibiotics and chemotherapeutic drugs was assessed. CONCLUSIONS: Investigation of the frequency of different bacterial species, along with monitoring of the resistance is an essential prerequisite of initial antibiotic therapy of febrile episodes in neutropenic patients.

Bacteria↗
PubMed1998

[Effectiveness of cefpirome on Klebsiella pneumoniae producing beta-lactamases with an extended spectrum of activity].

In the submitted paper the author investigated the effectiveness of cefpirome on Klebsiella pneumoniae strains producing beta-lactamases with an extended spectrum (ESBL). From a total of 1348 examined strains of Klebsiella pneumoniae ESBL production was confirmed in 59 strains (4.4%). Resistance of ESBL-positive strains of Klebsiella pneumoniae to ceftazidime was 83.1%, to cefotaxime 93.2%, while resistance to cefpirome was recorded only in 45.8%.

Cephalosporins↗
PubMed1998

[Occurrence of gram-negative non-fermenting rods in hemocultures and their sensitivity to antimicrobial agents].

In the period from January 1993 to June 1996 were at the Department of Microbiology of the University Hospital in Olomouc 122 strains of Gram-negative nonfermentative rod-shaped bacteria isolated from haemocultures. The majority represented the group of 51 strains of the genus Acinetobacter (41.8%), complex A. calcoaceticus-baumannii (Acb complex). The second largest group were 21 strains (17.2%) of Pseudomonas aeruginosa. These were followed by 17 strains (13.9%) of Stenotrophomonas maltophilia, 8 strains (6.6%) of non-Acb complex acinetobacters, 6 strains (4.9%) of Pseudomonas putida and 5 strains (4.1%) of Alcaligenes xylosoxidans. The remaining species were represented only by 1-2 strains. In three isolations was the identification impossible. The majority of strains (24.6%) were from the Department of Haematology of the University Hospital in Olomouc. The most frequent diagnoses in patients with positive haemocultures were leukemias and lymphomas (24.6%). The most effective tested antimicrobial agents were ceftazidime (93.4% of sensitive strains) and ofloxacin (91.7%). From the total number of 80 strains detected using the equipment BacT/Alert 120, 22 (27.5%) were isolated repeatedly confirming their role in the etiology of bacteriemic or septic episodes. Because only one blood sample was obtained in 34 cases (58.6%) of the remaining 58 only once detected strains, it was impossible to confirm their etiologic role by repeated isolation. (Tab. 6, Ref. 22.)

Blood↗
PubMed1996

[Comparison of the results of antibiotics sensitivity tests using the standard microdilution method on isolated bacteria and the direct disc method on positive hemocultures from the automatic BacT/Alert system].

During a six-month period 2,221 haemocultures obtained from patients hospitalized in the Faculty Hospital Olomouc were examined. In all 304 isolated bacteria the sensitivity was assessed by the standard dilution micromethod and moreover all positive haemocultures were examined the "direct" disc method. Agreement between the results of the two methods was proved in 84% of pairs of tests and within a range from 67 to 100%, depending on the type of antimicrobial preparation. Based on these findings it may be stated that assessment of the sensitivity by the "direct" method agrees significantly with assessment of the sensitivity according to minimal inhibitory concentrations (MIC). In patients with septicaemia this procedure makes it possible to change empirical antibiotherapy by 24 hours sooner to aimed therapy.

Bacteremia↗
PubMed1996

[Characteristics of multiresistant gram-negative bacteria and their occurrence at the Medical School Hospital in Olomouc].

Currently, a persistent growth of bacterial resistance to antibiotics takes place. Multiresistant bacterial strains thus represent a serious danger for therapy in practice. The aim of the study was to characterize the multiresistant Gram-negative bacteria and to judge their antibiograms by using the minimum inhibition concentrations (MIC). At the same time the study evaluates the relations to the most frequent diagnoses and epidemiologic data concerning the occurrence of these strains in different clinical cases treated at individual departments of the Faculty Hospital in Olomouc. Out of the total of 4.988 strains of Gram-negative rods, the number of isolated multiresistant strains reached 316 (6.3%). Individual bacterial species were isolated in the following order: Pseudomonas aeruginosa (28.8%), Enterobacter cloacae (23.4%) and Acinetobacter Baumannii complex (Acb complex) (18.7%). The most frequent occurrence of investigated bacteria was registered at the departments in the following order: urology (45.9%), internal medicine (18%), paediatrics (13.6%), and surgery (11.1%). The most frequent diagnoses based on positive cultivation of these bacteria were the infections of the urogenital tract (53.8%), postoperative infections (16.8%), and the infections of the upper respiratory ducts (7.3%). 64.2% of strains were cultivated from urine, 16.1% from pus, and 6.9% from swabs taken from the upper respiratory ducts. (Tab. 8, Ref. 18.).

Drug Resistance, Multiple↗