Bibliometric analysis of Helicobacter pylori resistance—from 2002 to 2022

Background

Drug resistance in Helicobacter pylori severely affects the efficacy of eradication therapy, and a number of studies have been conducted on this issue. The aim of this study was to assess the progress in this field using a bibliometric approach.

Materials and Methods

Publications related to H. pylori resistance from 2002 to 2022 were retrieved from the Web of Science database. Relevant information including titles, authors, countries, and keywords was extracted, and the data were processed using Excel, VOSviewer, and CiteSpace software for co-authorship, co-citation, and co-occurrence analysis.

Results

From 2002 to 2022 (as of 09/24/2022), the field of H. pylori–resistance research produced a total of 2677 publications with a total of 75217 citations, with an overall upward trend in the annual number of articles published, reaching a peak of 204 in 2019. Articles were mainly published in Q1 or Q2 journals, with Helicobacter (TP = 261) publishing the most literature, Baylor College of Medicine (TP = 68) and Deng-chyang wu (TP = 38) being the most prolific institutions and authors, respectively. China and the United States were the locations of most of the articles, accounting for 35.08% of the global publication volume. Keyword co-occurrence analysis divided H. pylori-resistance research into four clusters: “Therapeutic Strategies,” “Diseases,” “Mechanism Research and Epidemiology,” and “Drug Research.” “Drug research” and burst detection indicate that the current research hotspot involves the selection and analysis of treatment strategies.

Conclusions

H. pylori–resistance research has become a popular research field, and although there are significant contributions from Europe, the United States, and East Asia, there are significant imbalances between regions that cannot be ignored. In addition, the exploration of treatment strategies remains a key issue for research at the current stage.     

Phenotypic and genotypic traits of Shiga toxin-producing Escherichia coli strains isolated from beef cattle from Paraná State, southern Brazil

AIMS: To investigate the prevalence and characteristics of Shiga toxin-producing Escherichia coli (STEC) in cattle from Paraná State, southern Brazil. METHODS AND RESULTS: One hundred and seven faeces cattle samples were cultured on Sorbitol-MacConkey agar. Escherichia coli colonies were tested for production of Shiga toxin using Vero-cell assay. A high prevalence (57%) of STEC was found. Sixty-four STEC were serotyped and examined for the presence of stx(1), stx(2), eae, ehxA and saa genes and stx(2) variants. The isolates belonged to 31 different serotypes, of which three (O152:H8, O175:H21 and O176:H18) had not previously been associated with STEC. A high prevalence of stx(2)-type genes was found (62 strains, 97%). Variant forms found were stx(2), stx(2c), stx(2vhb), stx(2vO111v/OX393) and a form nonclassifiable by PCR-RFLP. The commonest genotypes were stx(2)ehxA saa and stx(1)stx(2)ehxA saa. CONCLUSIONS: A high frequency of STEC was observed. Several strains belong to serotypes previously associated with human disease and carry stx(2) and other virulence factors, thus potentially representing a risk to human health. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study of STEC in Paraná State, and its findings emphasize the need for proper cattle handling to prevent human contamination.     

An index of limnological conditions for urban wetlands of Bogotá city,Colombia

The urban wetlands of Bogotá are ecosystems of great importance, yet they are deteriorating. The state of deterioration must be evaluated in order to develop new methods of ecosystem monitoring and conservation. Here we describe the development of an index to assess the ecological health of five urban wetlands and one rural wetland from limnological data. The field phase of this study took place in November 2007 (rainy season) and February 2008 (dry season). Physical and chemical variables of the wetland ecosystems (temperature, dissolved oxygen, pH, conductivity, hardness, chlorides, ammonia, nitrites, nitrates, orthophosphates, and biological oxygen demand) were measured and samples of phytoplankton, periphyton, macroinvertebrates, and aquatic plants (macrophytes) were collected. The indices developed (biotic indices of communities: BI, and limnological conditions index: LICOI) allow classification of wetlands into three categories: those that have “acceptable limnological conditions” (Meridor, Jaboque and Guaimaral), those with “regular limnological conditions” (Santa María del Lago, Juan Amarillo) and those with “poor limnological conditions” (Tibanica). None of the environments studied fit a potential fourth category of “best limnological conditions.” The LICOI is a management tool that can be used to assess changes in wetlands after positive actions (restoration, cleaning, hydraulic management), or negative impacts (depletion, alien species, pollution). It also could allow regular monitoring of wetland evolution and serve as a basis for the development of indices measuring the ecological status of other aquatic environments in Colombia.     

Cloning,expression and some properties of α-carbonic anhydrase from Helicobacter pylori

The α-carbonic anhydrase gene from Helicobacter pylori strain 26695 has been cloned and sequenced. The full-length protein appears to be toxic to Escherichia coli, so we prepared a modified form of the gene lacking a part that presumably encodes a cleavable signal peptide. This truncated gene could be expressed in E. coli yielding an active enzyme comprising 229 amino acid residues. The amino acid sequence shows 36% identity with that of the enzyme from Neisseria gonorrhoeae and 28% with that of human carbonic anhydrase II. The H. pylori enzyme was purified by sulfonamide affinity chromatography and its circular dichroism spectrum and denaturation profile in guanidine hydrochloride have been measured. Kinetic parameters for CO₂ hydration catalyzed by the H. pylori enzyme at pH 8.9 and 25°C are k_cat=2.4×10⁵ s⁻¹, K_M=17 mM and k_cat/K_M=1.4×10⁷ M⁻¹ s⁻¹. The pH dependence of k_cat/K_M fits with a simple titration curve with pK_a=7.5. Thiocyanate yields an uncompetitive inhibition pattern at pH 9 indicating that the maximal rate of CO₂ hydration is limited by proton transfer between a zinc-bound water molecule and the reaction medium in analogy to other forms of the enzyme. The 4-nitrophenyl acetate hydrolase activity of the H. pylori enzyme is quite low with an apparent catalytic second-order rate constant, k_enz, of 24 M⁻¹ s⁻¹ at pH 8.8 and 25°C. However, with 2-nitrophenyl acetate as substrate a k_enz value of 665 M⁻¹ s⁻¹ was obtained under similar conditions.     

Phenotypic and genotypic diversity of airborne fungal spores in Demänovská Ice Cave (Low Tatras,Slovakia)

This paper is the first aero-mycological report from Demänovská Ice Cave. Fungal spores were sampled from the internal and external air of the cave in June, 2014, using the impact method with a microbiological air sampler. Airborne fungi cultured on PDA medium were identified using a combination of classical phenotypic and molecular methods. Altogether, the presence of 18 different fungal spores, belonging to 3 phyla, 9 orders and 14 genera, was detected in the air of the cave. All of them were isolated from the indoor samples, and only 9 were obtained from the outdoor samples. Overall, airborne fungal spores belonging to the genus Cladosporium dominated in this study. However, the spores of Trametes hirsuta were most commonly found in the indoor air samples of the cave and the spores of C. herbarum in the outdoor air samples. On the other hand, the spores of Alternaria abundans, Arthrinium kogelbergense, Cryptococcus curvatus, Discosia sp., Fomes fomentarius, Microdochium seminicola and T. hirsuta were discovered for the first time in the air of natural and artificial underground sites. The external air of the cave contains more culturable airborne fungal spores (755 colony-forming units (CFU) per 1 m³ of air) than the internal air (from 47 to 273 CFU in 1 m³), and these levels of airborne spore concentration do not pose a threat to the health of tourists. Probably, the specific microclimate in the cave, including the constant presence of ice caps and low temperature, as well as the location and surrounding environment, contributes to the unique species composition of aeromycota and their spores in the cave. Thus, aero-mycological monitoring of underground sites seems to be very important for their ecosystems, and it may help reduce the risk of fungal infections in humans and other mammals that may arise in particular due to climate change.     

Feasibility of using constructed treatment wetlands for municipal wastewater treatment in the Bogotá Savannah,Colombia

The main water bodies in the Bogotá Savannah have been seriously polluted due to the mismanagement of domestic, agricultural, and industrial wastewater. While there are a number of wastewater treatment facilities in the region, most do not function properly. There is a great need for inexpensive and sustainable wastewater treatment systems that are not technologically sophisticated and that do not require intensive management. The main goal of this study was to quantify the performance and sustainability of treatment wetlands and existing wastewater treatment systems in this region. Using data from the literature, a treatment wetland model was developed, which focused on pollutant removal. The modeled performance was compared to a system of waste stabilization ponds and a sequencing batch reactor. The three systems were subject to cost analysis and an emergy evaluation, leading to the assessment of indicators of cost-benefit for comparison. The economic analysis suggested that the net annual cost of the treatment wetland was US$ 14,672, compared to US$ 14,201 for the stabilization ponds and US$ 54,887 for the batch reactor. The emergy evaluations show that the ponds have the lowest annual emergy flow (6.65 + 16 sej/yr), followed by the constructed wetland (2.88E+17 sej/yr) and the batch reactor (8.86E+17 sej/yr). These results were combined to estimate treatment ratios (contaminants removed per lifetime cost, and contaminants removed per total emergy), cost ratios (cost per volume of water, annual cost per capita, and construction cost per capita), and emergy ratios (treatment yield, renewable emergy, lifetime emprice, construction emprice, non-renewable emergy, empower density, environmental loading, total emergy per volume of water, and emergy per capita).     

Historical, social and epidemiological roots of tuberculosis in Bogotá, Colombia

Understanding the current epidemiologic dynamic of tuberculosis (TB) in any society requires a holistic approach. In the current paper, the history and behavior of the TB is summarized for Bogotá, Colombia. In prehispanic periods the occurrence of TB was low. During the Conquest and the Colony periods, a moderate increase of pulmonary and abdominal TB was observed. In the 1870s, a great increase in cases of pulmonary TB was associated with the accelerated urbanization process. Since the 1920s, the occurrence of pulmonary TB shifted to the status of an endemic disease. After 1920, its occurrence was relatively steady until the 1970s, when its occurence greatly decreased. More recently, however, an increase in case numbers has been observed. The occurrence of TB in each period is associated with clearly defined social and environmental phenomena.     

Phenotypic and genotypic characteristics of shiga toxin-producing Escherichia coli strains isolated from children in São Paulo,Brazil

The biochemical and serological characteristics, virulence properties, and genetic relatedness of Shiga toxin-producing Escherichia coli (STEC) strains isolated in S o Paulo, from April 1989 through March 1990, were determined. This is also the first report on clinic findings of human STEC infections in Brazil. The only three STEC strains identified in that period were lysine decarboxylase negative, belonged to serotype O111ac: non-motile, were Stx1 producers, carried the eae and astA genes, and 2 of them also presented the EHEC-hly sequence. The children carrying STEC were all boys, with less than two years old, and had no previous history of hospitalization. None of them presented blood in stools. Vomiting, cough and coryza were the most common clinical manifestations observed. Although the STEC strains were isolated during summer months, and presented similar phenotypic and genotypic characteristics, carbohydrate fermentation patterns and PFGE analysis suggested that these diarrheal episodes were not caused by a single clone.     

Isolation and Characterization of Cryptococcus neoformans Varieties Recovered from Natural Sources in Bogotá, Colombia, and Study of Ecological Conditions in the Area

Cryptococcus neoformans, the etiological agent of cryptococcosis, has been associated with avian droppings and certain trees in different countries, including Colombia. C neoformans environmental isolates were obtained in urban areas in Bogotá, Colombia, and the strains recovered were phenotypically characterized. Attempts to determine the ecological conditions (micro- and macroclimatic) possibly related to their habitat were also undertaken. Four hundred and eighty samples from bark, soil around trunk bases, and detritus inside hollows of 32 trees were collected in three urban areas during a 5-month period, as well as 89 avian droppings samples from different places. Of plant samples, 6.7% collected from nine tree species yielded C. neoformans var. gattii, serotype B strains in 99% of the cases, and C. neoformans var. grubii, serotype A in 1%. The yeast was more frequently recovered from bark than from soil or detritus inside hollows, and from trees with hollows or rotted wood rather than from trees in which birds nest. C. neoformans was present with higher frequency and density in the rainy season than in the dry season; we found that slightly higher temperature and humidity values of the microhabitat, as compared to those of the environment, favored fungal occurrence, but the phenological state of the tree did not. Of dropping samples, 7.9% yielded C. neoformans strains, all of them C. neoformans var. grubii, serotype A. The yeast was obtained more frequently from dry droppings than from moist ones, but neither the sunlight exposure nor the site of collection of samples was correlated with this occurrence. Population density was significantly higher in droppings than in tree samples. Under laboratory conditions, isolates of different serotype showed similar capsular sizes. Water content and pH ranges were wide and did not show any significant difference between positive and negative samples.