Hrisi Bahar Tokman

Antimicrobial resistance of Helicobacter pylori strains to five antibiotics, including levofloxacin, in Northwestern Turkey

INTRODUCTION Antibiotic resistance is the main factor that affects the efficacy of current therapeutic regimens against Helicobacter pylori. This study aimed to determine the rates of resistance to efficacy clarithromycin, amoxicillin, tetracycline, levofloxacin and metronidazole among H. pylori strains isolated from Turkish patients with dyspepsia. METHODS H. pylori was cultured from corpus and antrum biopsies that were collected from patients with dyspeptic symptoms, and the antimicrobial susceptibility of H. pylori was determined using the E-test (clarithromycin, amoxicillin, tetracycline, metronidazole and levofloxacin) according to the EUCAST breakpoints. Point mutations in the 23S rRNA gene of clarithromycin-resistant strains were investigated using real-time PCR. RESULTS A total of 98 H. pylori strains were isolated, all of which were susceptible to amoxicillin and tetracycline. Of these strains, 36.7% (36/98) were resistant to clarithromycin, 35.5% (34/98) were resistant to metronidazole, and 29.5% (29/98) were resistant to levofloxacin. Multiple resistance was detected in 19.3% of the isolates. The A2143G and A2144G point mutations in the 23S rRNA-encoding gene were found in all 36 (100%) of the clarithromycin-resistant strains. Additionally, the levofloxacin MIC values increased to 32 mg/L in our H. pylori strains. Finally, among the clarithromycin-resistant strains, 27.2% were resistant to levofloxacin, and 45.4% were resistant to metronidazole. CONCLUSIONS We conclude that treatment failure after clarithromycin- or levofloxacin-based triple therapy is not surprising and that metronidazole is not a reliable agent for the eradication of H. pylori infection in Turkey.

Prevalence of Primary Antimicrobial Resistance of H. pylori in Turkey: A Systematic Review.

The prevalence of clarithromycin resistance has increased to the 20% or more in different regions of the world. Clarithromycin resistance is known to be responsible for most of the treatment failures in Helicobacter pylori (H. pylori) infection. The aim of this systematic review was to summarize the prevalence of primary antibiotic resistance (amoxicillin, clarithromycin, metronidazole, levofloxacin, tetracycline) of H. pylori strains in different geographical regions of Turkey.

Isolation and diagnosis of Helicobacter pylori by a new method: microcapillary culture.

AIM To investigate the performance of the microcapillary culture method (MCM) in Helicobacter pylori (H. pylori) isolation and diagnosis. METHODS Microcapillary culture (MC), classical culture (CC), rapid urease (CLO) test, and histopathologic examination (HE) were performed with biopsy samples. Homogenized biopsy samples were loaded into capillary tubes and incubated for 48 h at 37 °C without providing a microaerophilic environment. Additionally, three or four loops of the homogenized sample were inoculated in a ready-to-use selective medium (Becton Dickinson, Helicobacter Agar, Modified) specific for the isolation of H. pylori and incubated at 37 °C in a microaerophilic atmosphere provided by CampyGen (Becton Dickinson, GasPack). Bacteria reproducing in microcapillary tubes were evaluated in an inverted microscope and also were evaluated after performing a CC with the content. Results obtained by CC, CLO test, and HE were compared with those of MC. The diagnostic performances of the methods used in this study were evaluated for specificity, sensitivity, positive predictive value (PPV), negative predictive value (NPV), and CI. RESULTS H. pylori was found positive by CLO test + HE and/or CC culture in 26 patient antrum and corpus biopsy samples. In 25 (25/26) patient biopsy samples, H. pylori was isolated by MCM, whereas in only 14 (14/26) patient biopsy samples, H. pylori was isolated by CC. CLO test and HE were found positive in 17 (17/26) patient biopsy samples. Comparing the results of the isolation of H. pylori by MCM, CC, CLO test, and HE, the sensitivity of the MCM was found as 96%, the specificity as 80%, the PPV as 83%, the NPV as 95%, and the 95%CI as 0.76 (χ (2) = 31.51, P < 0.01) whereas the sensitivity of the CC was found as 54% (χ (2) = 19.15, P < 0.01), and the sensitivity of the CLO test and HE were found as 65% (χ (2) = 25.26, P < 0.01). CONCLUSION This new microcapillary cultivation method for H. pylori has high diagnostic sensitivity compared with CC, HE, and CLO tests.

The cytokine response in THP-1 (monocyte) and HL-60 (neutrophil-differentiated) cells infected with different genotypes of Helicobacter pylori strains.

BACKGROUND/AIMS Helicobacter pylori (H. pylori) is a microaerophilic bacterium related with peptic ulcer and gastric cancer. Its virulence factors include cytotoxin-associated gene A (CagA) and vacuolating cytotoxin gene A (VacA) proteins. Cytokine release inducted by H. pylori colonization has an important role in pathogenesis of H. pylori. The severity of gastric pathologies depends on the H. pylori genotypes found in different geographical regions. We aimed to determine the relationship between different H. pylori genotypes and their effects on the cytokine release levels. MATERIALS AND METHODS ureC, cagA, vacAs1/s2, vacAm1/m2, and blood group antigen-binding adhesion protein A2 (babA2) virulence related genes were investigated in 21 H. pylori strains. Genotyping of 21 strains were made due to the presence of cagA, vacAs1/s2, vacAm1/m2, and babA2 genes. The H. pylori strains were cultured together with THP-1 and neutrophil-differentiated Human promyelocytic leukemia cells (HL-60) cells. The levels of cytokines interleukin (IL)-1β, IL-6, IL-8, IL-12, tumor necrosis factor-alpha (TNF-α), and IL-10 in these cells were measured after co-culturing with H. pylori strains. RESULTS The following five different genotypes were detected: Genotype1: cagA and vacAs1m2; Genotype2: cagA and vacAs1m1; Genotype3: cagA, vacAs1m2, and babA2; Genotype4: vacAs2m2; and Genotype5: cagA and vacAs2m2. All these genotypes significantly induced the levels of IL-1β, IL-6, IL-8, IL 10, and TNF-α in THP-1 cells. Genotype 5 caused higher amounts of IL-1β, IL-6, TNF-α, and IL-10, whereas genotype 1 induced the highest levels of IL-8. In neutrophil-differentiated HL-60 cells, genotype 4 increased IL-6 levels and genotype 3 and 4 elevated IL-8 levels significantly. CONCLUSION These results suggested that cytokine response of the host varies depending on the specific immune response of the host against different H. pylori strains.

The prevalence of enterotoxin and antibiotic resistance genes in clinical and intestinal Bacteroides fragilis group isolates in Turkey.

This study was conducted to measure the antibiotic susceptibilities, corresponding gene contents, and the enterotoxin gene bft, in 50 Bacteroides fragilis group isolates, 25 of which were clinical and 25 intestinal. The resistance rates to amoxicillin/clavulanic acid, imipenem and metronidazole were low; ampicillin and tetracyclin resistance was high; clindamycin resistance and ermF gene presence was also high. Regarding phenotypical bacterial resistance and the presence of resistance genes, there was not statistically significant difference between clinical and intestinal isolates and bft positive and negative isolates.

An in Vitro Experimental Study on the Antimicrobial Activity of Silicone Oil against Anaerobic Bacteria

Abstract Purpose: To investigate the in vitro antimicrobial activity of silicone oil against anaerobic agents, specifically Propionibacterium acnes, Peptostreptococcus spp., Peptostreptococcus anaerobius, Bacteroides fragilis, Fuobacterium spp., and Clostridium tertium. Method: A 0.5 McFarland turbidity of Propionibacterium acnes, Peptostreptococcus spp., Peptostreptococcus anaerobius, Bacteroides fragilis, Fuobacterium spp., and Clostridium tertium was prepared, and 0.1 mL was inoculated into 0.9 mL of silicone oil. Control inoculations were performed in anaerobic blood agar and fluid thioglycollate medium without silicone oil. Results: Propionibacterium acnes retained their viability on the 3rd day in the presence of silicone oil. In total, 9.7 × 106 colonies were enumerated from 1 mL of silicone oil. After a prolonged incubation of 7 days, the number of colonies observed was 9.2 × 106. The other bacteria disappeared after the 3rd day of incubation in silicone oil. Conclusions: Propionibacterium acnes, which is the most common chronic postoperative endophthalmitis agent, is thought to be resistant to silicone oil.

Microorganisms in Respiratory Tract of Patients Diagnosed with Atypical Pneumonia: Results of a Research Based on the Use of Reverse Transcription Polymerase Chain Reaction (RT-PCR) DNA

BACKGROUND Numerous molecular-based tests were applied for the laboratory-based diagnosis of viruses. In this cross-sectional case control study, in addition to bacteria, we aimed to determine respiratory viruses using, for the first time in our country, the Reverse Transcription PCR DNA Microarray method, and we also aimed to evaluate its diagnostic performance. METHODS Respiratory viruses were investigated from nasopharyngeal swabs of 76 patients diagnosed with atypical pneumonia and 64 healthy controls using the CLART Pneumovir (Genomica, Spain) kit and from 10 mL blood samples of the same subjects. M. pneumoniae IgM was detected by ELISA and L. pneumophila IgM and C. pneumoniae IgM by indirect immunofluorescence. Persons chi-square test was used for statistical analysis. RESULTS Our results showed that the specificity (100%) and the positive predictive value (100%) of the CLART Pneumovir kit were high, but its sensitivity (53%), its negative predictive value (64%), and its kappa value (50%) were low. Parainfluenza Virus type 3 and M. pneumoniae were found alone or together as the most common microorganisms while no cases of human bocavirus, adenovirus, rhinovirus, or coronavirus were detected. CONCLUSIONS Our results demonstrated that, during the study period, most of our patients had atypical pneumonia due to Parainfluenza Virus type 3 and M. pneumoniae co-infection.

Diagnostic performance of the RT-qPCR method targeting 85B mRNA in the diagnosis of pulmonary Mycobacterium tuberculosis infection

BACKGROUND Several nucleic acid amplification techniques (IS6110, 16S rRNA, and 85B mRNA) were developed for the rapid, direct detection of Mycobacterium tuberculosis. We aimed to assess the diagnostic performance of 85B mRNA-based RT-qPCR by comparing with the real-time PCR COBAS TaqMan MTB Kit while using the BACTEC MGIT 960 method as the gold standard. METHODS 60 patients with confirmed pulmonary TB and 60 individuals without TB were included as the study and control groups, respectively. Sputum specimens were cultured using LJ and BACTEC MGIT 960 systems. Extracted DNA was used for COBAS PCR in a CONAS TaqMan 48 analyzer. 85B mRNA detection was performed by RT-qPCR. RESULTS The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of COBAS TaqMan MTB Test were detected as 93.3%, 83.3%, 84.8%, 92.6%, and 88.3%, respectively. The same diagnostic parameters of RT-qPCR were: 98.3%, 95.0%, 95.2%, 98.3%, and 96.7%, respectively. According to the binary logistic regression analysis, RT-qPCR (OR: 19,924, p<0.001) was identified as the more optimal test. CONCLUSION RT-qPCR targeting the 85B gene of M. tuberculosis seems to be a more useful and rapid technique than DNA-based methods for detecting live M. tuberculosis bacilli from sputum specimens.

The relationship of Chlamydophila pneumoniae with schizophrenia: The role of brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) in this relationship

Several pathogens have been suspected of playing a role in the pathogenesis of schizophrenia. Chronic inflammation has been proposed to occur as a result of persistent infection caused by Chlamydophila pneumoniae cells that reside in brain endothelial cells for many years. It was recently hypothesized that brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) may play prominent roles in the development of schizophrenia. NT-3 and BDNF levels have been suggested to change in response to various manifestations of infection. Therefore, we aimed to elucidate the roles of BDNF and NT3 in the schizophrenia-C. pneumoniae infection relationship. RT-PCR, immunofluorescence and ELISA methods were used. Fifty patients suffering from schizophrenia and 35 healthy individuals were included as the patient group (PG) and the healthy control group (HCG), respectively. We detected persistent infection in 14 of the 50 individuals in the PG and in 1 of the 35 individuals in the HCG. A significant difference was found between the two groups (p<0.05). Twenty-two individuals in the PG and 13 in the HCG showed seropositivity for past C. pneumoniae infection, and no difference was observed between the groups (p>0.05). C. pneumoniae DNA was not detected in any group. A significant difference in NT-3 levels was observed between the groups, with very low levels in the PG (p<0.001). A significant difference in BDNF levels was also found, with lower levels in the PG (p<0.05). The mean serum NT-3 level was higher in the PG cases with C. pneumoniae seropositivity than in seronegative cases; however, this difference was not statistically significant (p>0.05). In conclusion, we suggest that NT-3 levels during persistent C. pneumoniae infection may play a role in this relationship.

The protective role of Helicobacter pylori neutrophil-activating protein in childhood asthma

BACKGROUND Helicobacter pylori quantity and HP-NAP gene expression were evaluated in the faeces of healthy and asthmatic children. METHODS H. pylori DNAs and RNAs were isolated from the stool samples of 92 asthmatic children (AC; 3-8 years) and 88 healthy controls (HC). Quantitative PCR was used to determine the quantity of H. pylori and HP-NAP expression relative to the 16S rRNA (reference gene). Gene expression was analysed using the delta delta-Ct method. RESULTS H. pylori DNA was detected in the stool samples of 18 (20.4%) of the 88 HC (p<0.0001, OR=0.79) and none of AC. No meaningful statistical differences were found between individuals with positive and negative family histories for asthma in AC and HC (p>0.05). H. pylori quantity was higher in seven of 18 H. pylori-positive samples, but HP-NAP expression levels were low in four of these seven samples. Based on a multivariate logistic regression analysis of these three variables together, only males displayed a significant difference based on gender differences (p<0.02) and it was determined that, based on the OR value of 0.46 and the 95% CI range of 0.241-0.888, male gender was an independent protective factor in asthma. CONCLUSIONS HP-NAP levels vary to the relative concentrations of bacteria in the stationary or late logarithmic phases. Different napA expression levels may be caused by different endogenous napA gene expression or different environmental conditions.