Case of misdiagnosed melioidosis from Hue city, Vietnam.

Melioidosis is an emerging infection, a potentially fatal tropical disease caused by Burkholderia pseudomallei in humans and animals, endemic in Southeast Asia and northern Australia. Diagnosis remains problematic due to its similarity to many other infections. The lack of clinical awareness and correct microbiological diagnosis contributes to the misidentification of melioidosis. We present a melioidosis case, which was misdiagnosed with pneumonia and septicemia due to Aeromonas salmonicida, leading to ineffective prolonged-course antibiotic treatment for the patient.

Characterisation of point mutations in domain V of the 23S rRNA gene of clinical Helicobacter pylori strains and clarithromycin-resistant phenotype in central Vietnam.

OBJECTIVES: The prevalence of clarithromycin (CLR)-resistant Helicobacter pylori is increasing worldwide, including in Vietnam. The aims of this study were to determine point mutations in the 23S rRNA domain V of clinical H. pylori strains in central Vietnam, to estimate the prevalence of phenotypic CLR resistance and to assess the association between 23S rRNA domain V genotype and CLR-resistant phenotype. METHODS: Sequencing of the 23S rRNA domain V of H. pylori strains from gastric biopsy specimens was performed for 185 patients with H. pylori-positive chronic gastritis, of which 104 samples were subjected to susceptibility testing to determine CLR resistance. RESULTS: A total of 24 types of point mutation were detected. A2143G and A2142G mutations were observed in 40.5% and 4.3%, respectively. New point mutations were detected (C2041T, C2083T, C2191T, G2220A, G2225A, G2240A, C2273T, T2276C, G2287A, C2399T, A2445G and C2622T). 23S rRNA domain V genotypes were diversified, with combinations of two or more point mutations as well as single point mutations. The rate of phenotypic CLR resistance was 53.8%, increasing from 40.4% in 2012-2014 to 70.2% in 2015-2017 (P=0.0045). A2143G and A2142G accounted for 89.3% of phenotypically CLR-resistant H. pylori isolates. CONCLUSIONS: A diversity of point mutations in the 23S rRNA domain V was observed in clinical H. pylori isolates. The rate of phenotypically CLR-resistant H. pylori is significantly increasing in central Vietnam. Further research is necessary to clarify the role of the combination of 23S rRNA domain V mutations in the molecular mechanism of CLR resistance.

Genotyping of Helicobacter pylori shows high diversity of strains circulating in central Vietnam.

In Vietnam, the high prevalence of Helicobacter pylori infection represents a serious health problem. Virulence genes of H. pylori have been associated to increased risk of severe gastrointestinal diseases and the genetic background differs in geographical areas. We investigated cagA and vacA genotypes of H. pylori from dyspeptic patients from central Vietnam and the correlation with clinical outcomes; we also performed sequencing analysis of partial cagA gene. Overall, 84% of strains were cagA-positive, 75% were East-Asian type with a prevalence of vacAs1i1m1 and vacAs1i1m2 genotypes (66.7% and 33.3%, respectively) and 9% were Western type vacAs1i1m1 (n=4) and vacAs1i1m2 (n=4); vacAs1i2m2 (n=4) and vacAs2i2m2 (n=2) genotypes were associated to cagA-negative. Strains from gastric ulcer and cancer were of East-Asian type, while cagA-negative or Western strains were from gastritis and duodenal ulcer. H. pylori strains from gastric ulcer patients were predominantly vacAs1i1m1 compared to other vacA genotypes (p<0.05). East-Asian type strains vacAs1i1m1 or vacAs1i1m2 were found in gastric cancer patients and also in less severe disease. Phylogenetic tree analysis of CagA sequences showed the co-circulation of H. pylori of different geographical origins with Western sequences closer related to Cambodia, one of the entry of Western strains in Southeast-Asia through human migrations. Sequence analysis revealed in two Western type strains a chimeric CagA-3' region with identity with East-Asian CagA suggesting recombination event in the process of evolution among East-Asian and Western H. pylori strains. Moreover, polymorphism in CagA multimerization (CM) motif was observed including new East-Asian CM motifs. In conclusion, we have found in central Vietnam a geographically dependent diversity of cagA genotype, with higher rates of cagA-negative and Western-type strains compared with other nation's parts that can partly explain the lower risk of gastric cancer. The polymorphism of CM motifs may explain the variability of disease manifestations of vacAs1i1m1 and s1i1m2 East-Asian isolates.

A novel toolbox to investigate tissue spatial organization applied to the study of the islets of Langerhans.

Thanks to the development of new 3D Imaging techniques, volumetric data of thick samples, especially tissues, are commonly available. Several algorithms were proposed to analyze cells or nuclei in tissues, however these tools are limited to two dimensions. Within any given tissue, cells are not likely to be organized randomly and as such have specific patterns of cell-cell interaction forming complex communication networks. In this paper, we propose a new set of tools as an approach to segment and analyze tissues in 3D with single cell resolution. This new tool box can identify and compute the geographical location of single cells and analyze the potential physical interactions between different cell types and in 3D. As a proof-of-principle, we applied our methodology to investigation of the cyto-architecture of the islets of Langerhans in mice and monkeys. The results obtained here are a significant improvement in current methodologies and provides new insight into the organization of alpha cells and their cellular interactions within the islet's cellular framework.

Antimicrobial resistance in Helicobacter pylori: current situation and management strategy in Vietnam.

Increasing antimicrobial resistance to key antibiotics in Helicobacter pylori has become a main cause of treatment failures in many countries, including Vietnam. For this reason it is advisable to perform antimicrobial sensitivity tests to provide more focused regimens for H. pylori eradication. However, this approach is generally unavailable for H. pylori in Vietnam and the selection of treatment regimens is mainly based on the trend of antibiotic use in the population, resistance development in the region, and history of H. pylori eradication of patients. The aim of this review is to examine the current situation of antimicrobial resistance in Vietnam and suggest management strategies for treatment selection.

High rate of levofloxacin resistance in a background of clarithromycin- and metronidazole-resistant Helicobacter pylori in Vietnam.

Antimicrobial resistance in Helicobacter pylori has increased worldwide and has become a major cause of treatment failure in many countries, including Vietnam. It is advisable to perform an antibiogram to provide optimal regimens for H. pylori eradication. This study evaluated the rate of antibiotic resistance to the four commonly used antibiotics against H. pylori at a tertiary care hospital in Central Vietnam and analysed point mutations in genes related to clarithromycin (CLA) and levofloxacin (LFX) resistance. A total of 92 H. pylori strains from gastric biopsy specimens were tested; 42.4% were resistant to CLA (primary, 34.2%; secondary, 73.7%), 41.3% to LFX (primary, 35.6%; secondary, 63.2%), 76.1% to metronidazole (MTZ) and 1.1% to amoxicillin. Multidrug resistance was observed in 56.5% (primary, 50.7%; secondary, 78.9%) of isolates (P<0.05). The rate of resistance to LFX was significantly higher in females than males (P<0.05). Most of the CLA- and LFX-resistant strains harboured resistance-associated mutations, with common positions at A2143G and T2182C in the 23S rRNA gene and at Asn-87 or Asp-91 in GyrA. Minimum inhibitory concentrations (MICs) increased in strains carrying quadruple mutations in their 23S rRNA gene and in strains with Asn-87 GyrA mutation (P<0.05). One high-level LFX-resistant strain (MIC=32mg/L) had new mutations with a combination of N87A, A88N and V65I. High resistance rates to CLA, MTZ and LFX discourage standard and LFX-based triple therapies as first-line treatment in Vietnam.

Integron-associated antibiotic resistance in Salmonella enterica serovar typhi from Asia.

Eighteen of 25 isolates of Salmonella enterica serovar Typhi were multidrug resistant and contained class 1 integrons with a single cassette, dfrVII or aadA1. The dfrVII-containing integron was likely borne on an IncHI1 plasmid. Salmonella serovar Typhi could become resistant to broad-spectrum cephalosporins by integrating cassettes, such as veb-1, a common cassette in Asia.