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Öğe The Effect of Phosphate Limitation on Rhamnolipid Production and Related Quorum Sensing Signal Molecules in Pseudomonas aeruginosa(Bilimsel Tip Yayinevi, 2019) Bukavaz, SebnemIntroduction: Rhamnolipid (RL) is one of the virulence factor secreted from Pseudomonas aeruginosa and is required to establish and persist the infection. The control of RL production is under control of Quorum Sensing System, and it is influenced by numerous factors of environmental/nutritional levels. In this study, it was aimed to investigated the phosphate depletion effect on selected Quorum Sensing Signal Molecules (QSSMs) under condition of rhamnolipid production. Materials and Methods: The effect of phosphate on RL production was examined in P. aeruginosa PAO1 and RL mutant strains by Orcinol and TLC plate test. Additionally, HPLC/MS quantification for QSSMs related to rhamnolipid production was carried out using the samples isolated from 16, 24 and 48 h cultures grown in Luria-Bertani (LB) and Proteose Peptone Glucose Amonium Salt (PPGAS) medium. Results: The increase in rhamnolipid production in PPGAS medium, for the wild type strain (48 h) amounted up to 20 fold was achieved compared to LB media by Orcinol assay. The cultures from PPGAS medium supplemented with 50 mM phosphate displayed significantly lower amount of rhamnolipid in 48 and 72 h cultures by 54% and 64%, respectively. The highest concentration of QSSMs were the C4-HSL and PQS for all strains. Then, the QSSM profile was followed by 3-oxo-C12-HSL and HHQ. Conclusion: Phosphate limitation increased rhamnolipid production via RhlR and PQS systems in P. aeruginosa PAO1. Considering the fact that other virulence factors are activated while rhamnolipid production is increased, phosphate limitation leads to an increase in the virulence of P. aeruginosa.Öğe Molecular Identification of Campylobacter Species Isolated from Patients with Gastroenteritis in Edirne, Turkey(Galenos Publ House, 2022) Eryildiz, Canan; Sakru, Nermin; Tabakcioglu, Kiymet; Ugur, Mediha Cerrah; Bukavaz, SebnemBACKGROUND/AIMS: Campylobacter is a major cause of foodborne diarrheal disease, and the incidence of campylobacteriosis has significantly increased in both developed and developing countries. The purpose of the present study was to identify the species of Campylobacter isolates and to evaluate the distribution of Campylobacter infections according to various characteristics in our region. MATERIALS AND METHODS: Campylobacter isolates obtained from patients at a tertiary hospital in Edirne, Turkey were included in this study. The distribution of Campylobacter infections was evaluated according to age, season, and gender. Species identification was performed by multiplex polymerase chain reaction (PCR). The RNA polymerase beta-subunit gene (rpoB) of selected samples was amplified, and DNA sequencing was performed. RESULTS: Campylobacter species were isolated from 226 (4.3%) of the 5,241 samples. One hundred and seventy-six (89.3%) of 197 samples were identified as C. jejuni and 19 (9.6%) as C. coli by multiplex PCR. Two isolates showed a band profile compatible with both C. jejuni and C. coli. DNA sequencing was performed for 21 isolates. Sixteen isolates were compatible with C. jejuni and 5 isolates were consistent with C. coli. There was no statistically significant difference in Campylobacter isolation rates according to gender and season (p>0.05). Campylobacter species were most frequently isolated from children in the age group of 0-14 years (p<0.01). CONCLUSION: Campylobacter is one of the main causes of diarrhea in Turkey, and this infection is more common in children. This study contributes to information about the situation of Campylobacter infection and the genetic features of isolates in Turkey.Öğe A Rarely Isolated Bacterium in Microbiology Laboratories: Streptococcus uberis(Ankara Microbiology Soc, 2017) Eryildiz, Canan; Bukavaz, Sebnem; Gurcan, Saban; Hatipoglu, OsmanStreptococcus uberis is a gram-positive bacterium that is mostly responsible for mastitis in cattle. The bacterium rarely has been associated with human infections. Conventional phenotyphic methods can be inadequate for the identification of S. uberis; and in microbiology laboratories S. uberis is confused with the other streptococci and enterococci isolates. Recently, molecular methods are recommended for the accurate identification of S. uberis isolates. The aim of this report is to present a lower respiratory tract infection case caused by S. uberis and the microbiological methods for identification of this bacterium. A 66-year-old male patient with squamous cell lung cancer who received radiotherapy was admitted in our hospital for the control. According to the chest X-Ray, patient was hospitalized with the prediagnosis of cavitary tumor, pulmonary abscess''. In the first day of the hospitalization, blood and sputum cultures were drawn. Blood culture was negative, however, Candida albicans was isolated in the sputum culture and it was estimated to be due to oral lesions. After two weeks from the hospitalization, sputum sample was taken from the patient since he had abnormal respiratory sounds and cough complaint. In the Gram stained smear of the sputum there were abundant leucocytes and gram-positive cocci, and S. uberis was isolated in both 5% sheep blood and chocolate agar media. Bacterial identification and antibiotic susceptibility tests were performed by VITEK 2 (Biomerieux, France) and also, the bacterium was identified by matrix assisted laser desorption/ionization time of flight mass spectrometry (MALDITOF MS) based VITEK MS system as S. uberis. The isolate was determined susceptible to ampicillin, erythromycin, clindamycin, levofloxacin, linezolid, penicillin, cefotaxime, ceftriaxone, tetracycline and vancomycin. 16S, 23S ribosomal RNA and 16S-23S intergenic spacer gene regions were amplified with specific primers and partial DNA sequence analysis of 16S rRNA polymerase chain reaction (PCR) products were performed by 3500xL Genetic Analyzer (Applied Biosystems, USA). According to the partial 16S rRNA gene sequencing results, bacterium was confirmed as S. uberis. This report makes a significant contribution to the number of case reports of human infections caused by S. uberis as the identification was performed by current microbiological methods in our case. In conclusion, S. uberis should be evaluated as an opportunistic pathogen among the immunosuppressed patients and in addition to phenotypic bacteriological methods, the other recent microbiological methods should also be utilized for the identification.Öğe The Relationship Between Virulence Factors of Helicobacter pylori and Severity of Gastritis in Infected Patients(Springer, 2009) Umit, Hasan; Tezel, Ahmet; Bukavaz, Sebnem; Unsal, Gulbin; Otkun, Muserref; Soylu, Ali Riza; Tucer, DilekThe outcome of Helicobacter pylori infection has been related to specific virulence-associated bacterial genotypes. The best known genotypic virulence factors of H. pylori are cytotoxin-associated gene A (cagA) and vacuolating cytotoxin gene A (vacA). The objective of this study was to assess the relationship between H. pylori cagA and vacA status and histopathological findings. Esophagogastrodoedonoscopy was performed in 80 dyspeptic patients. Antrum and corpus biopsies were obtained for isolation of H. pylori and for histopathological assessment. The polymerase chain reaction was used to detect cagA and vacA genes of H. pylori using specific primers. Biopsy samples were stained with hematoxylin and eosin, and histopathological findings were graded using the updated Sydney system. H. pylori from 57 of the 80 patients was incubated. Of the 57 patients, 44 were cagA positive. In the corpus biopsy specimens there was a significant relationship between the density of H. pylori colonization (P = 0.02) and chronic inflammation (P = 0.02) and cagA-positive genotypes. In the antrum specimens there was a significant relationship between cagA positivity and neutrophil activity (P = 0.003) and glandular atrophy (P = 0.002), but not with H. pylori density, chronic inflammation, and intestinal metaplasia. The odds ratio of cagA-positive vs. cagA-negative strains for the presence of glandular atrophy, irrespective of grading and of gastric localization, was 4.62 (95% CI, 1.18-18.08, P = 0.041). No significant relationships were observed between vacA s1 and s2 genotypes and histopathological parameters. Corpus neutrophil infiltration was found to be more severe in the m1 group than in the m2 group (P = 0.004). Other histopathological features showed no difference between m1 and m2 genotypes. In conclusion H. pylori strains showing cagA positivity are associated with more severe gastritis in some histological features but virulence factors of H. pylori do not appear to determine the overall pattern of gastritis.
