Prevalence of Helicobacter pylori in symptomatic patients and detection of clarithromycin resistance using melting curve analysis

AbstractBackground:Clarithromycin is often a component of combination therapies for Helicobacter pylori eradication; however, increases in resistance rates have decreased the success of the treatment.Objective:This study was designed to determine the prevalence of H pylori infection in symptomatic patients and to detect clarithromycin resistance rates using melting curve analysis.Methods:Patients scheduled for upper endoscopy at the Endoscopy Unit of the Department of Gastroenterology, Duzce University, Medical Faculty Hospital, Konuralp/Duzce, Turkey, were assessed for enrollment in the study. Two pairs of gastric biopsy specimens (antrum and corpus) were obtained from each study patient. Histopathologic examination, rapid urease test, culture, and polymerase chain reaction (PCR) of the specimens were used to identify H pylori infection. Clarithromycin resistance was detected using melting curve analysis.Results:Seventy-five patients (41 women, 34 men; mean [SD]age, 42.6 [14.5] years [range, 17–70 years]) were included in the study. Using histopathology and rapid urease test, H pylori was detected in 40 (53.3%) of the 75 specimens. H pylori was detected using PCR in 40 (53.3%) specimens and by culture in 10 (13.3%) specimens. The specificity and sensitivity of PCR and culture were interpreted by comparing them with the results of histopathologic examination and urease tests. The specificity and sensitivity of PCR were 68.6% and 72.5%, respectively, and the specificity and sensitivity of culture were 97.1% and 22.5%, respectively. Of the 40 isolates, 21 (52.5%) were susceptible to clarithromycin, 12 (30.0%) were resistant, and a mixed susceptibility pattern was detected in 7 (17.5%) specimens. H pylori isolates from 19 (79.2%) of the 24 patients who had formerly used clarithromycin showed clarithromycin resistance.Conclusions:The prevalence of H pylori infection was 53.3% for the symptomatic patients in this study, and 47.5% of the isolates showed clarithromycin resistance using melting curve analysis. The PCR-based system used in this study was accurate for the detection of H pylori infection as well as clarithromycin susceptibility testing directly in biopsy specimens

Validation of a Blood Culture System Via Correlation Between Microorganism Concentration and Positive Result

Introduction: Quick and accurate determination of the pathogens that invade the circulatory system requires the validation of the blood culture system used in the laboratory. In this study, the growth of microorganisms in different concentrations that were experimentally inoculated into BACTEC blood culture media was monitored by BACTEC 9240 blood culture system, and relations between microorganism species, concentration and time to positivity signal were investigated. Materials and Methods: A total of 239 strains isolated from clinical specimens, including Enterobacteriaceae, Staphylococcus aureus and Staphylococcus spp., Enterococcus spp., beta-hemolytic streptococci, Candida spp., and nonfermentative bacilli were included in this study. A decreasing order of six dilutions were prepared from the strains, and blood culture bottles were experimentally inoculated by these dilutions within 10 mL of expired, volunteer donor whole blood, and the times to positivity were monitored. Results: The relation between bacterial concentration and time to positivity signal was statistically significant for Enterobacteriaceae and gram-positive cocci (p 0.05). Conclusion: BACTEC 9240 blood culture system was validated for Enterobacteriaceae and gram-positive cocci. Validation of the system for Candida species and nonfermentative bacilli was not accomplished. The system has been shown to have a limitation regarding its inability to detect growth of some dilutions of Candida and nonfermentative bacilli. It was thought that the microscopic examination of the blood culture bottles that tested negative by the system or subculturing may be useful in the routine laboratory procedure and may avoid this limitation of the automated blood culture system. Furthermore, if there is a suspicion of fungal infection, using selective fungal medium and following cultures up to 21 days would be appropriate

Prevalence of Helicobacter pylori in symptomatic patients and detection of clarithromycin resistance using melting curve analysis

WOS: 000248245200003PubMed: 24683206Background: Clarithromycin is often a component of combination therapies for Helicobacter pylori eradication; however, increases in resistance rates have decreased the success of the treatment. Objective: This study was designed to determine the prevalence of H pylori infection in symptomatic patients and to detect clarithromycin resistance rates using melting curve analysis. Methods: Patients scheduled for upper endoscopy at the Endoscopy Unit of the Department of Gastroenterology, Duzce University, Medical Faculty Hospital, Konuralp/Duzce, Turkey, were assessed for enrollment in the study. Two pairs of gastric biopsy specimens (antrum and corpus) were obtained from each study patient. Histopathologic examination, rapid urease test, culture, and polymerase chain reaction (PCR) of the specimens were used to identify H pylori infection. Clarithromycin resistance was detected using melting curve analysis. Results: Seventy-five patients (41 women, 34 men; mean [SD] age, 42.6 [14.5] years [range, 17-70 years]) were included in the study. Using histopathology and rapid urease test, H pylori was detected in 40 (53.3%) of the 75 specimens. H pylori was detected using PCR in 40 (53.3%) specimens and by culture in 10 (13.3%) specimens. The specificity and sensitivity of PCR and culture were interpreted by comparing them with the results of histopathologic examination and urease tests. The specificity and sensitivity of PCR were 68.6% and 72.5%, respectively, and the specificity and sensitivity of culture were 97.1% and 22.5%, respectively. Of the 40 isolates, 21 (52.5%) were susceptible to clarithromycin, 12 (30.0%) were resistant, and a mixed susceptibility pattern was detected in 7 (17.5%) specimens. H pylori isolates from 19 (79.2%) of the 24 patients who had formerly used clarithromycin showed clarithromycin resistance. Conclusions: The prevalence of H pylori infection was 53.3% for the symptomatic patients in this study, and 47.5% of the isolates showed clarithromycin resistance using melting curve analysis. The PCR-based system used in this study was accurate for the detection of H pylori infection as well as clarithromycin susceptibility testing directly in biopsy specimens