Evaluation the cytotoxic effect of cytotoxin-producing Klebsiella oxytoca isolates on the HEp-2 cell line by MTT assay

Background: The cytotoxic effects on epithelial cells of the human are not observed in other strains of Klebsiella spp and are only observed in K. oxytoca strains. MTT assay was used to evaluate cytotoxic activity. In this study, colorimetric method was used to evaluate the cytotoxic effect of cytotoxin-producing isolates on Hep-2 cell line and determines the percentage of surviving cells. Materials and methods: In this study, we collected a total of 75 K. oxytoca strains isolate and we detected the production of toxins and their cytotoxic effects on HEp-2 cells. Colorimetric method such as MTT assay was used to evaluate the cytotoxic effect of cytotoxin-producing isolates on Hep-2 cell line and determines the percentage of surviving cells. Results: Nine isolates had cytotoxic effects on HEp-2 cells. The results of MTT assay showed that the isolated strains were different from the control stain in terms of toxinogenicity and cytotoxic effects on HEp-2 cells at the studied dilutions (1:3, 1:6, 1:12, 1:24, 1:48, and 1:96). Conclusions: In the current study, Percentage of Hep-2 surviving cells exposed to 1:3, 1:6, 1:12, 1:24, 1:48, and 1:96 supernatant dilutions of cytotoxin-producing Klebsiella oxytoca isolates was different

High level of resistance to metronidazole and clarithromycin among Helicobacter pylori clinical isolates in Qazvin province, Iran

The treatment of patients with Helicobacter pylori infection has many limitations, especially because of antibiotic resistance. We aimed to investigate the prevalence and mechanism of antibiotic resistance to metronidazole and clarithromycin in H. pylori isolates collected from patients with gastrointestinal symptoms in Qazvin, Iran. In this cross-sectional study, antibiotic susceptibility testing to clarithromycin and metronidazole was performed among 80 clinical strains isolated from H. pylori-positive dyspeptic patients referred to Qazvin hospital from July 2018 to November 2018. Polymerase chain reaction (PCR) and sequencing tests were performed to determine the type of mutations in the rdxA gene in metronidazole-resistant isolates, and the 23SrRNA gene in clarithromycinresistant isolates. Thirteen (40.6%) and Twenty-one (65.6%) isolates were resistant to clarithromycin and metronidazole, respectively. 37.5% and 59.4% of clarithromycin and metronidazole resistant isolates had MIC>256. In clarithromycin-resistant isolates, mutations in the 23SrRNA gene was seen at A2143G (15.6%), A2142G (9.4%), C2195T (6.3%), C2244T (3.1%), and G2212A (3.1%) locations. In one isolate, three simultaneous mutations were recorded in locations A2143G, G2110A, and C2121T. Mutations in the rdxA gene in metronidazole-resistant isolates, were missense. High resistance to metronidazole and clarithromycin antibiotics were seen in H. pylori isolates in Qazvin province. This is the frst report of new mutation sites G2212A, G2110A, and C2121T on the 23SrRNA gene in clarithromycin-resistant isolates. It is necessary to evaluate the current situation in terms of resistance and identify the mechanisms involved in its occurrence for the successful treatment of infections caused by this organism

High level of resistance to metronidazole and clarithromycin among Helicobacter pylori clinical isolates in Qazvin province, Iran

resistance. We aimed to investigate the prevalence and mechanism of antibiotic resistance to metronidazole and clarithromycin in H. pylori isolates collected from patients with gastrointestinal symptoms in Qazvin, Iran. In this cross-sectional study, antibiotic susceptibility testing to clarithromycin and metronidazole was performed among 80 clinical strains isolated from H. pylori-positive dyspeptic patients referred to Qazvin hospital from July 2018 to November 2018. Polymerase chain reaction (PCR) and sequencing tests were performed to determine the type of mutations in the rdxA gene in metronidazole-resistant isolates, and the 23SrRNA gene in clarithromycinresistant isolates. Thirteen (40.6%) and Twenty-one (65.6%) isolates were resistant to clarithromycin and metronidazole, respectively. 37.5% and 59.4% of clarithromycin and metronidazole resistant isolates had MIC>256. In clarithromycin-resistant isolates, mutations in the 23SrRNA gene was seen at A2143G (15.6%), A2142G (9.4%), C2195T (6.3%), C2244T (3.1%), and G2212A (3.1%) locations. In one isolate, three simultaneous mutations were recorded in locations A2143G, G2110A, and C2121T. Mutations in the rdxA gene in metronidazole-resistant isolates, were missense. High resistance to metronidazole and clarithromycin antibiotics were seen in H. pylori isolates in Qazvin province. This is the first report of new mutation sites G2212A, G2110A, and C2121T on the 23SrRNA gene in clarithromycin-resistant isolates. It is necessary to evaluate the current situation in terms of resistance and identify the mechanisms involved in its occurrence for the successful treatment of infections caused by this organism