Helicobacter pylori Mutations Conferring Resistance to Fluoroquinolones and Clarithromycin among Dyspeptic Patients Attending a Tertiary Hospital, Tanzania.

Objectives. Helicobacter pylori (H. pylori) isolates resistant to clarithromycin and quinolones are increasing worldwide. Data regarding the magnitude of H. pylori resistance are limited in developing countries. Here, we report the prevalence of mutations conferring resistance to clarithromycin and fluoroquinolones among dyspeptic patients attending a tertiary hospital, Tanzania. Methods. Between August 2014 and August 2016, patients undergoing upper gastrointestinal endoscopy at the Bugando Medical Centre were enrolled. Biopsies were taken for polymerase chain reaction (PCR) and sequencing to detect mutations conferring resistance to clarithromycin and fluoroquinolones. Results. A total of 208 nonrepetitive biopsies were examined of which 188 (90.4%) tested positive for H. pylori specific 23S rRNA PCR. Clarithromycin resistance mutations were detected in 54/188 (28.7%) of patients tested. The most frequently detected mutation was A2143G (30) followed by A2142G (20). Out of 131 nonrepetitive biopsies tested for fluoroquinolones resistance mutations, 77/131 (58.8%) were positive, with N87I (20) mutation being the most frequently detected mutation followed by A92T mutation which was detected in 16 samples. Conclusion. A significant proportion of dyspeptic patients attending tertiary hospital in Tanzania are infected with H. pylori strains harbouring clarithromycin or fluoroquinolones resistance mutations. Detection of more than 50% of strains with fluoroquinolones resistance mutations makes the H. pylori second line treatment questionable in our setting. There is a need of surveillance of H. pylori resistance patterns in Tanzania to provide data that can guide empirical treatment to reduce associated morbidity of H. pylori infections. The correlation between A92T fluoroquinolone mutation and phenotypic resistance requires further investigations.

Transferrin receptor induction in Toxoplasma gondii-infected HFF is associated with increased iron-responsive protein 1 activity and is mediated by secreted factors.

Infection with the apicomplexan parasite Toxoplasma gondii results in a significant alteration of the host-cell transcriptional profile. We have previously shown that the transferrin receptor (TfR) is specifically up-regulated in T. gondii-infected human fibroblasts but not in host cells infected with the bacterial pathogens Salmonella Typhimurium and Chlamydia trachomatis. In this report, we describe the prerequisites and physiological conditions that are associated with this pathogen-specific gene induction. Band-shift assays revealed that T. gondii infection resulted in increased activity in the iron response protein IRP1, which, in this state, stabilizes TfR mRNA from degradation. Although T. gondii depends on host-cell iron as demonstrated by sensitivity to deferoxamine, a parasite-induced iron starvation is not responsible for TfR up-regulation. The increased iron availability due to treatment with holotransferrin and FeNTA did not prevent TfR induction nor was the transferrin-independent iron-transporter NRAMP2 up-regulated in infected host cells. In addition, inhibition of parasite replication by drug treatment did not prevent TfR up-regulation. Instead, TfR induction was sensitive to cycloheximide and could be induced by treatment with conditioned media from infected human fibroblasts. Together our findings suggest that the T. gondii-specific TfR up-regulation is not due to a direct interaction of parasitic factors with the iron-uptake machinery of the host cell but is instead mediated indirectly as a result of secreted host cell- or parasite-derived factors.