Biomedical subjects

Ozgen Köseoğlu

Publications and source records attributed to Ozgen Köseoğlu.

6 recordsLinked to original sources

PubMed2005

[The prevalence of nasopharyngeal Neisseria meningitidis carriage, serogroup distribution, and antibiotic resistance among healthy children in Cankaya municipality schools of Ankara province].

Meningococci responsible for significant morbidity and mortality rates in children are found in the oropharynx and nasopharynx and communicated with droplets. In this study, the prevalence of nasopharyngeal Neisseria meningitidis carriage, serogroup distribution and antibiotic resistance were determined among healthy children in Cankaya municipality of Ankara province. The study involved 1155 students aged 7-19 years. Systematic sampling method was used for sample selection. To isolate N. meningitidis, modified Thayer-Martin medium was used. The antibiotic susceptibilities of N. meningitidis isolates were determined by agar dilution method for penicillin, sulfadiazine, rifampicin, and azithromycin. N. meningitidis carriage prevalence was found as 10.4% with serogroup B being the most predominant (47.5%). The prevalence of N. meningitidis carriage was found to be closely associated with living conditions however, tonsillectomy, tonsillar hypertrophy, passive or active smoking did not affect the rate of carriage. Overcrowded life style, use of old-fashioned stoves for heating, and living in shanty housing were determined as risk factors increasing N. meningitidis carriage. None of the strains showed beta-lactamase activity, and five strains (4.2%) had decreased sensitivity to penicillin. The resistance against sulfadiazine was 54.4%, while it was 26.9% against azithromycin. No rifampicin-resistant strain were detected. It can be concluded that the prevalence of meningococcal carriage in this study was similar to that of other European countries. Rifampicin should be the first drug of choice both for the treatment of meningococcal carriers and for the prophylaxis of the subjects who had been in contact with patients with meningococcal infection.

Adolescent↗

PubMed2004

[A novel T-cloning vector system].

The use of cloning vectors has revolutionized molecular biology. Any vector with appropriate cloning sites can be used to clone a section of DNA and polymerase chain reaction (PCR) is a useful method for producing DNA fragments that are intended to be cloned. When Taq polymerase is used in PCR for polymerization, the enzyme adds an extra adenosyl (A) nucleotide to the 3' end of the extended strand, in a template independent manner. T-cloning vectors are created by adding a thymidine (T) residue to the ends of the cloning site. This aids ligation with PCR products possessing A-T. In this study, we prepared a T-cloning vector system, which guarantees insertion of open reading frames to the right position for expression. This method provides an easy way of cloning PCR products assuring at the same time in frame insertion.

Cloning, Molecular↗

PubMed2004

[Integrons].

The development of antimicrobial resistance has led to the discovery of many natural mobile elements like transposons and conjugative plasmids. Integrons are carried on plasmids and transposons that potentially increase the dissemination of antibiotic resistance genes among bacterial species. Integrons are genetic elements containing the determinants of a site-specific recombination system. These DNA elements mediate the integration of antibiotic resistance genes into bacteria through the site-specific recombination. Integrons consist of an integrase gene (intl), a recombination site (attl), and one or two promoters responsible for expression of the inserted gene cassettes. Class 1 integrons are the most commonly studied and largely implicated type in the dissemination of antibiotic resistance among clinical isolates. In the last few years, a variety of new gene cassettes coding antibiotic resistance have been described. Having the ability of horizontal transfer of antibiotic resistance genes between interspecies of bacteria, integrons play a dominant role in the development of multiresistance in Enterobacteriaceae. In this review article, classification, structure and expression, epidemiology and clinical importance of integrons, has been discussed.

Drug Resistance, Bacterial↗

PubMed2004

[Molecular characterization of BRO beta-lactamases of Moraxella catarrhalis strains isolated from carrier children].

Nasopharyngeal carriage of Moraxella catarrhalis is a risk factor for upper respiratory tract infections and otitis media. In this study, we aimed to characterize BRO beta-lactamases of M. catarrhalis strains isolated from 64 children without any symptoms of respiratory disease. Gram negative diplococci grown on selective media and which are catalase, oxidase, DNase, nitrate reduction positive, glucose, maltose, sucrose and lactose fermentation negative, were diagnosed as M. catarrhalis. Antibiotic susceptibility testing was performed by agar dilution method recommended by NCCLS. BRO beta-lactamases were differentiated by restriction enzyme analysis method. The resistance rate for ampicillin was 18.8% and all the isolates were found to be sensitive to amoxicillin-clavulanate, cefazolin, cefaclor, azithromycin and ciprofloxacin. Out of 64 M. catarrhalis isolates, 57 (89%) were found beta-lactamase positive with nitrocefin disk test (Remel, USA). The presence of BRO beta-lactamases in these 57 strains (89%) was also confirmed by restriction enzyme analysis, while 7 (11%) of them were found to be negative. Among the positive strains, 47 (73.4%) were typed as BRO-1, and 10 (15.6%) were typed as BRO-2. The characterization of BRO beta-lactamases of M. catarrhalis strains in carrier children is important since the high rate of carriage predisposes to respiratory tract infections. As a result, BRO beta-lactamase typing will guide the treatment regimen against the respiratory infections that can occur due to M. catarrhalis in carrier children.

Ampicillin Resistance↗

PubMed2002

[Streptococcus pneumoniae strains resistance to macrolide, lincosamide, streptogramin, oxazolidinone and ketolide].

Over the last two decades, antimicrobial resistance in Streptococcus pneumoniae has been detected at an increasing rate. There have been several reports of increasing rate of macrolide resistance among the penicillin-resistant S. pneumoniae strains. The rapid evolution of such resistance necessitated new antimicrobials, such as streptogramins, oxazolidinones and ketolides, against beta-lactam and macrolide resistant pneumococci. This study was undertaken to determine the prevalence of macrolide resistance in pneumococci isolated in a Turkish University hospital and also to determine the activity of these newly developed agents against pneumococci. For that purpose a total of 264 pneumococci, isolated from clinical specimens, were tested for susceptibility against penicillin, erythromycin, clarithromycin, clindamycin, quinupristin/dalfopristin, linezolid and telithromycin by agar dilution method. Penicillin resistance and intermediate penicillin resistance was found in 7.6% and 40% of isolates respectively, while resistance rates of the tested isolates against erythromycin, clarithromycin and clindamycin were as 15.9%, 13.6% and 13.6%, respectively. Resistance to macrolides and clindamycin was higher among the penicillin-resistant isolates. No resistance was detected against quinupristin/dalfopristin, linezolid and telithromycin, except for four strains which had minimal inhibitory concentration (MIC) values of intermediately susceptible category to quinupristin/dalfopristin. These data indicate the presence of an important percentage of macrolide resistant pneumococci in our hospital. It can also be concluded that streptogramins, oxazolidinones and ketolides may be used as good alternatives especially in case of infections due to macrolide resistant pneumococci.

Anti-Bacterial Agents↗

PubMedDate not supplied

[Molecular epidemiology of Stenotrophomonas maltophilia strains isolated from paediatric patients].

As alternative regimens in therapy of Stenotrophomonas maltophilia infections are limited, epidemiological investigation of S. maltophilia is necessary for developing new strategies in prophylaxis of these infections. "Enterobacterial repetetive intergenic consensus-polymerase chain reaction (ERIC-PCR)", is a simple and rapid method to detect the genomic polymorphism at the strain level in nosocomial outbreaks due to S. maltophilia. The aim of this study was to investigate the molecular epidemiology of S. maltophilia strains isolated from paediatric patients in a university hospital. A total of 40 clinical isolates one from each of 35 patients, two pairs from two patients and one from an environmental source, were collected between 1998-2001 period. Susceptibility to eleven antimicrobials was studied by agar dilution test according to NCCLS criteria. Resistance rates of the tested isolates against piperacillin, piperacillin-tazobactam, ceftriaxone, ceftazidime, cefepime, ciprofloxacin, imipenem, meropenem, amikacin, gentamicin and trimethoprim-sulfamethoxazole were 57.5%, 25%, 85%, 37.5%, 47.5%, 20%, 100%, 95%, 62.5%, 62.5% and 5%, respectively. Trimethoprim-sulfamethoxazole was the most active agent against the tested isolates. The isolates were analyzed by ERIC-PCR by using each of ERIC-I and ERIC-II primers. Genotypic analysis by ERIC-PCR identified 24 different major and 4 minor profiles. Three isolates from each of four different groups, two isolates from each of other four different groups were unique. The results of this study, revealing a great genomic diversity and low clonality within the strains of S. maltophilia strains suggest that patients may be colonized with the naturally occuring isolates in the hospital environment and then get infected with these strains under the selective antibiotic pressure, thus supporting the view that clonal spread of S. maltophilia strains between patients is of rather low possibility.

Anti-Infective Agents↗