High Resistant Strains Research Articles

Cold atmospheric plasma as a promising tool in treatment of Trichophyton rubrum-induced skin infection in a guinea pig model of experimental dermatophytosis

The emergence of high-resistance strains to known antifungal drugs has highlighted the urgency of developing novel therapies for chronic dermatophytosis as a global health problem. An experimental dermatophytosis model in guinea pigs was developed to investigate the in vivo wound healing effects of cold atmospheric plasma (CAP) on T. rubrum skin invasion. Guinea pigs were experimentally infected with T. rubrum and wound healing was evaluated at 1, 4, 8 and 12 days post infection in the CAP-treated, terbinafine-treated and non-treated controls. Our results showed that CAP strongly inhibited the fungal virulence in vitro in culture media and in vivo on the skin lesions of experimentally infected guinea pigs even more efficient than that of terbinafine, resulting in complete wound healing at 8 days post infection. These results indicate that CAP would be considered as a promising tool comparable to conventional chemical therapies, for the treatment of drug-resistant chronic dermatophytosis caused by T. rubrum.

Changing Face of Antimicrobial Resistance: A Cross-Sectional Study

Introduction Infections of sterile body fluids are significant contributors to mortality and morbidity. Accurate species-level identification and understanding of the antimicrobial resistance profiles are crucial for selecting appropriate antimicrobials for empirical and targeted therapy. This study aims to examine the distribution of various bacterial species and their evolved antimicrobial resistance profiles isolated from different body fluids. Methods This retrospective study evaluated 301 body fluid samples collected at a tertiary hospital between January 2023 and December 2023. Samples were gram-stained and cultured on an appropriate media. Bacterial identification and susceptibility testing were performed using the BD Phoenix™ system, with disk diffusion method used for antibiotics not available in the system. Results Microbial growth was detected in 151 cases (50.2%), with a comparable prevalence among males and females (53.0% vs. 46.7%). The mean age was 49.81± 24.1 years. Growth rates were slightly higher in hospital-acquired infections (55.7%) than in community-acquired infections (49.2%). Cerebrospinal fluid showed the highest growth rate at 34.3%. Among the isolates, Streptococcus species were the most common (14.6%), while Escherichia coli was the predominant Gram-negative bacterium (13.2%). Sensitivity was highest with tigecycline (100%) and meropenem (92%), whereas resistance was most notable against ampicillin-sulbactam (100%) and azithromycin (95.2%). Multidrug resistance was identified in 106 isolates (70.2%). Conclusion High antibiotic resistance and multidrug-resistant strains underscore the need for rigorous antibiotic stewardship and improved infection control to address untreatable infections.

Molecular dynamics simulation of pyruvate kinase to investigate improved thermostability of artificially selected strain in Enterococcus faecium

BackgroundEnterococcus faecium (E. faecium) is a member of symbiotic lactic acid bacteria in gastrointestinal tract and it was successfully used to treat diarrhea cases in humans. For a lactobacteria to survive during the pasteurization process, resistance of proteins to denaturation at high temperatures is crucial. Pyruvate kinase (PYK) is one of the proteins possessing such property. It plays a major role during glycolysis by producing pyruvate and adenosine triphosphate (ATP).ObjectiveTo assess the acquired thermostability of PYK of ALE strain using in silico methods.MethodsFirst, we predicted and assessed tertiary structures of our proteins using SWISS-MODEL homology modelling server. Second, we then applied molecular dynamics (MD) simulation to simulate and assess multiple properties of molecules. Therefore, we implemented comparative MD to evaluate thermostability of PYK of recently developed high temperature resistant strain of E. faecium using Adaptive Laboratory Evolution (ALE) method. After 20ns of simulation at different temperatures, we observed that ALE enhanced strain demonstrated slightly better stability at 300, 340 and 350 K compared to that of the wild type (WT) strain.ResultsWe collected the results of MD simulation at four temperature points: 300, 340, 350 and 400 K. Our results showed that the protein demonstrated increased stability at 340 and 350 K.ConclusionResults of these study suggest that PYK of ALE enhanced strain of E. faecium demonstrates overall better stability at elevated temperatures compared to that of WT strain.

Characterization of high fluoride resistant Pseudomonas aeruginosa species isolated from water samples

Groundwater fluoride contamination is one of the most serious toxicological environmental issues in India and around the world. Water samples were taken from Natham taluk and screened for fluoride resistant bacteria. Initially, twenty-four fluoride resistant colonies were selected from 50 mM NaF supplemented LB agar plates. On blood agar plates, all isolates showed β-haemolysis, confirming their status as pathogens. Virulence factors (algD, plcH, toxA, gyrB, rhlC, lasB) and biofilm-forming genes (ppyR, pelA, pslA) were identified in these isolates by PCR analysis. The fluoride ion transporter ‘crcB’ was successfully amplified from these isolates by gene-specific PCR. Genus Pseudomonas and P. aeruginosa species-specific PCR analysis identified that all strains as belonging to the P. aeruginosa species. Besides, three high fluoride resistance strains were selected based on high fluoride resistance and confirmed as P. aeruginosa species by 16S rRNA sequencing and NCBI blast analysis.

Multifunctional hybrid hydrogel with transparency, conductivity, and self-adhesion for soft sensors using hemicellulose-decorated polypyrrole as a conductive matrix

Polymers with high conductivity and cross-linking ability are ideal materials for the preparation of conductive hydrogels for application in wearable electronic devices. However, the fabrication of conductive polymer-incorporated hydrogels with good synergistic properties remains a great challenge due to the hydrophobicity and opacity of conjugated π conductive polymers. In this study, a multifunctional hybrid hydrogel was prepared by incorporating hemicellulose-decorated polypyrrole (H/PPY), polyvinyl alcohol (PVA), and tannic acid (TA) into a polyacrylamide (PAM) network. The addition of excess ammonium persulfate (APS) in the process of gelation not only initiated the polymerization of PAM but also resulted in the change of the hydrogel from opaque to transparent by continuously breaking and reducing the size of the PPY particles. The hybrid hydrogel exhibited high transparency and conductivity, good adhesion ability and mechanical performance, and high resistance strain sensitivity and could accurately monitor the strain signals of the index finger and elbow flexion and pulse beat during rest and exercise, which has promising potential for use in wearable or implantable smart sensor devices, electronic skins, and artificial intelligence applications.

Research on technical production of Trichoderma preparations for control of yellow leaf - root rot on citrus trees

It is necessary to study conditions biomass multiplication and production of microbial organic fertilizers from Trichoderma for citrus trees, to help improve soil and prevent Fusarium sp., Phytophthora sp. causes yellow leaf - root rot. This study used two very high resistance strains of Trichoderma fungi for culture, namely T.haz.22.QH and T.asp.11.TT. Cultures of Trichoderma in liquid medium with the composition of extract from 150 g bean sprouts + 30 g sugar + 1 g urea + 1 g KH2P04 + 0.5 g MgSO4achieved the highest biomass of 4.35±0.48 g/l after 1 day. Solid fermentation medium using simmered whole-grain rice substrate and 10% fungal juice were suitable for fast growth and spores 8.82x109 CFU/g and obtained fungal biomass after 5-6 days. Producing micro-organic fertilizers using 100% manure or 50% bagasse + 50% manure with 6-8 kg of Trichoderma and obtained faecal biomass after 60 days of incubation.

Metabolomic and Transcriptomic Responses of Argopecten irradians concentricus to Thermal Stresses

The bay scallop southern subspecies, Argopecten irradians concentricus, which is widely cultured in southern China waters, is a eurythermal animal that is more adaptive to high-temperature waters but less tolerant to low-temperature waters. Despite that temperature is one of the most dominant environmental factors affecting dramatically its growth, survival, and hence production, the mechanism underlying the responses to thermal stress has not been explored in this animal. In this study, transcriptomic and metabolomic analyses were carried out in the adductor muscles of the bay scallop southern subspecies exposed to low and high thermal stresses. Transcriptomic analyses revealed that differentially expressed genes (DEGs) were enriched in the calcium ion, kinase activity, phosphatase activity, and lipid-related pathways in the group exposed to thermal stress, while most DEGs were enriched in the RNA processing pathways in the group exposed to low-temperature thermal stress. A large number of differentially expressed transcription factors involved in oxidation-reduction process, membrane-related pathways, transmembrane signaling receptor activity, and transduction-related pathways were induced by exposure to thermal stress. Results from metabolomic analyses showed that the retinol metabolism, inositol phosphate metabolism, and phosphatidylinositol pathways may be involved in the responses to high thermal stress, while more signaling pathways were enriched in the group exposed to low thermal stress. Integrated analyses of the transcriptomic and metabolomic data indicated that the degradation of valine, leucine, and isoleucine and the tricarboxylic acid cycle may be the major events induced by low and high thermal stress, and the retinol pathway may play critical roles in the responses of the scallops to high thermal stress. It seems that the bay scallop southern species have evolved distinct pathways in dealing with low and high thermal stress. Our results may provide useful information for marker-assisted selection of high-resistant strains in this scallop.

Resistance analysis of grape Botrytis cinerea based on PCR and sequencing technology.

Resistance of grape Botrytis cinerea was analyzed based on PCR and sequencing technology, which provided a reasonable basis for guiding the species and usage of grape Botrytis cinerea. 104 monospora strains of grape B. cinerea were collected from the main grape-producing areas of China. After isolation and purification, the grape B. cinerea DNA was extracted, and PCR primers were designed according to the resistance mechanism of pyrimethene to pyrimethamines, pyridamines and diformolines. Sequence analysis showed that the resistance frequency of B. cinerea to pyrimidine was 22.22%-62.5%, the high-resistant strain frequency was 44.23%, and the mid-temperature zone was 62.5%. The total resistance rate of B. cinerea to pyrimidine was 42.60%. The resistance rate of B. cinerea to pyrimidine was 42.60%. Resistance frequencies of grape gray mold strains were significantly different. The resistance frequencies of grape gray mold strains to pyridimide were significant. The highest resistance frequencies of grape gray mold strains were 53.42% in the cool temperature zone. Only 3.85% of grape gray mold strains showed resistance to pyridimide. Therefore, the resistance of Grape B. cinerea to pyrimidine and pyrimidine is relatively common, and the resistance to enoylmorpholine is still in the initial stage.

The Effect of Using Herbal Extracts as Irrigant Solution in Disinfecting Root Canals of Endodontically Treated Teeth: A Narrative Review

Objectives: The use of herbal medicine continues to grow worldwide in all fields including dentistry. The constant use of chemical products in the root canal treatment process has prompted researchers to look for herbal alternatives due to the side effects and the relatively high resistant microbial strains available in the root canal that can contribute to the refractory infection. Therefore, the aim of this narrative review is to evaluate the effectiveness of using selected herbal extracts in disinfecting the root canals and removing the smear layer of the endodontically treated teeth. Design: Systematic search from 1999-2019 was performed using four electronic databases. The level of evidence of eligible studies was assessed using Critical Appraisal Skills Programme and Cochrane risk of bias tools. Results: A total of 44 eligible experimental studies that assessed aloe vera, turmeric, Peganum harmala, green tea, garlic and chamomile extracts were retrieved electronically. Potent disinfectant properties provided by the herbal extract of the six selected plants were demonstrated. Among these herbal extracts, garlic and chamomile extracts were found to have better properties in removing the smear layer from the root canal compared to the other herbal extracts. Conclusion: The results of the present review support the use of the examined herbal extracts in disinfecting the root canal; however, these findings need to be assessed clinically to determine the possibility of using herbal products as a successful alternative for chemical products within the process of root canal treatment.

Genomic and Transcriptomic Analysis of Bovine Pasteurella multocida Serogroup A Strain Reveals Insights Into Virulence Attenuation.

Pasteurella multocida is one of the primary pathogens of bovine respiratory disease (BRD), and causes huge losses in the cattle industry. The Pm3 strain was a natural isolate, which is a strong form of pathogen and is sensitive to fluoroquinolones antibiotics. A high fluoroquinolone resistant strain, Pm64 (MIC = 64 μg/mL), was formed after continuous induction with subinhibitory concentration (1/2 MIC) of enrofloxacin, with the enhanced growth characteristics and large attenuation of pathogenicity in mice. This study reports the whole genome sequence and the transcription profile by RNA-Seq of strain Pm3/Pm64. The results showed an ineffective difference between the two strains at the genome level. However, 32 genes could be recognized in the gene islands (GIs) of Pm64, in which 24 genes were added and 8 genes were lost. Those genes are involved in DNA binding, trehalose metabolism, material transportation, capsule synthesis, prophage, amino acid metabolism, and other functions. In Pm3 strain, 558 up-regulated and 568 down-regulated genes were found compared to Pm64 strain, from which 20 virulence factor-related differentially expressed genes (DEGs) were screened. Mainly differentially transcribed genes were associated with capsular polysaccharide (CPS), lipopolysaccharide (LPS), lipooligosaccharide (LOS). Iron utilization, and biofilm composition. We speculated that the main mechanism of virulence attenuation after the formation of resistance of Pm64 comes from the change of the expression profile of these genes. This report elucidated the toxicity targets of P. multocida serogroup A which provide fundamental information toward the understanding of the pathogenic mechanism and to decreasing antimicrobial drugs resistance.

Effective removal of heavy metals in industrial wastewater with novel bioactive catalyst enabling hybrid approach

Recent years, heavy metal reduction of contaminated atmosphere using microbes is heightened worldwide. In this context, the current study was focused on heavy metal resistant actinomycete strains were screened from effluent mixed contaminated soil samples. Based on the phenotypic and molecular identification, the high metal resistant actinomycete strain was named as Nocardiopsis dassonvillei (MH900216). The highest bioflocculent and exopolysaccharide productions of Nocardiopsis dassonvillei (MH900216) was confirmed by various invitro experiments result. The heavy metal degrading substances was characterized and effectively confirmed by Fourier transform infrared spectroscopy (FT-IR), X-Ray Diffraction (XRD), Scanning electron microscope (SEM). Further, the heavy metal sorption ability of actinomycete substances bioflocculent was exhibited 85.20%, 89.40%, 75.60%, and 51.40% against Cd, Cr, Pb and Hg respectively. Altogether, the bioflocculent produced actinomycete Nocardiopsis dassonvillei (MH900216) as an excellent biological source for heavy metal reduction in waste water, and it is an alternative method for effective removal of heavy metals towards sustainable environmental management.

Determination of Antibacterial Effect of Nannochloropsis oculata Against Some Rainbow Trout Pathogens

In this study, antibacterial activity of Nannochloropsis oculata which were grown in proper culture condition was searched with their extracts that obtain by using different solvent (methanol, ethanol, chloroform). The antibacterial effects of algal extracts were evaluated by using disc diffusion method against L. garvieae, F. psychrophilum and Y. ruckeri. As the results of the study, it was found that the chloroform extracts of N. oculata showed strong antibacterial activities, F. psychrophilum was the high resistant strain against to antibacterial effects of the extracts, L. garvieae and Y. ruckeri were the two most susceptible bacteria strains. The results confirm the possible use of N. oculata as a source of antimicrobial compounds or as a health-promoting food for aquaculture.

The Effect of Aqueous Extract of Quercus infectoria Plant on Pap E gene Expression of Uropathogenic Escherichia coli

One hundred twelve urine samples were collected from Baghdad hospitals and examined by differentidentification techniques. Seventy isolates (62.5%) were diagnosed as Escherichia coli after microscopicand cultural identifications. The result of PCR product electrophoresis on the isolates showed that thirteenisolates (18.57%) have Pap E gene which are uropathogenic E. coli. Antibiotic susceptibility test was done,and four high resistant strains were mixed with aqueous extract of Quercus infectoria plant in 96 well ELISAplate and incubated for different times. After 0, 6, and 12 hr. of incubation, the effect of the plant extract onthe bacterial growth was determined by ELISA reader, and the effect on the expression of Pap E gene wasexamined by real-time PCR. The results were showed that the higher effect of the extract was on the E10strain growth that dropped from 3.184 at zero time of incubation to 2.378 and 2.281 after 6, and 12 hrs. ofincubation respectively. Also, shown a downregulation in the expression of Pap E gene of the isolates atdifferent times of incubation. The E10 strain shows decrease in the fold from 1 before the treatment with theextract to 0.076 at zero time of incubation with the extract, after 6 and 12 hrs. of incubation it shows a totaldown-regulation of the gene.

Adjunctive S100A8/A9 Immunomodulation Hinders Ciprofloxacin Resistance in Pseudomonas aeruginosa in a Murine Biofilm Wound Model.

Objective Pseudomonas aeruginosa is known to contribute to the pathogenesis of chronic wounds by biofilm-establishment with increased tolerance to host response and antibiotics. The neutrophil-factor S100A8/A9 has a promising adjuvant effect when combined with ciprofloxacin, measured by quantitative bacteriology, and increased anti- and lowered pro-inflammatory proteins. We speculated whether a S100A8/A9 supplement could prevent ciprofloxacin resistance in infected wounds.MethodFull-thickness 2.9cm2-necrosis was inflicted on 32 mice. On day 4, P.aeruginosa in seaweed alginate was injected sub-eschar to mimic a mono-pathogenic biofilm. Mice were randomized to receive ciprofloxacin and S100A8/A9 (n=14), ciprofloxacin (n=12) or saline (n=6). Half of the mice in each group were euthanized day 6 and the remaining day 10 post-infection. Mice were treated until sacrifice. Primary endpoint was the appearance of ciprofloxacin resistant P.aeruginosa. The study was further evaluated by genetic characterization of resistance, means of quantitative bacteriology, wound-size and cytokine-production.ResultsThree mice receiving ciprofloxacin monotherapy developed resistance after 14 days. None of the mice receiving combination therapy changed resistance pattern. Sequencing of fluoroquinolone-resistance determining regions in the ciprofloxacin resistant isolates identified two high-resistant strains mutated in gyrA C248T (MIC>32µg/ml) and a gyr B mutation was found in the sample with low level resistance (MIC=3µg/ml). Bacterial densities in wounds were lower in the dual treated group compared to the placebo group on both termination days.ConclusionThis study supports the ciprofloxacin augmenting effect and indicates a protective effect in terms of hindered ciprofloxacin resistance of adjuvant S100A8/A9 in P.aeruginosa biofilm infected chronic wounds.

1227. Plazomicin Susceptibility Testing using ETEST® MIC for Enterobacterales

BackgroundPlazomicin (PLZ) approved by FDA in June of 2018, is an aminoglycoside class antibacterial indicated for the treatment of adults with complicated urinary tract infections (cUTI) including pyelonephritis caused by Enterobacterales. It is used in patients who have limited or no alternative treatment options, e.g. CRE and MDRO patients. The drug has bactericidal activity, it is active against organisms producing ESBL, Carbapenemase and aminoglycoside-modifying enzymes. The purpose of this study was to compare ETEST® PLZ bioMérieux to the broth microdilution reference method (BMD) for Citrobacter freundii, Enterobacter cloacae, Escherichia coli, Klebsiella oxytoca and pneumoniae, Morganella morganii, Providencia stuartii, Proteus mirabilis and vulgaris and Serratia marcescens isolates.MethodsA total of 598 isolates were tested by ETEST® (PLZ) and BMD at four clinical trial sites.Isolates were subcultured on tryptic soy or Columbia agar plates supplemented with 5% sheep blood. Suspensions of the isolates were prepared in 0.85% saline, which were used to inoculate BMD and Mueller Hinton agar for ETEST®. Results were read after 16-20 hours incubation at 35°C +2°C in ambient air. QC organisms were tested with each run following CLSI QC guidelines.Results were analyzed using FDA breakpoints for PLZ (Susceptible <2 µg/mL, Intermediate 4 µg/mL, Resistant >8 µg/mL).Performance was evaluated using FDA performance criteria, EA and CA (≥ 90%), major error rate (≤3.0%) and very major error rate (≤2.0%).ResultsTable 1.Table 1. Performance for Plazomicin ETEST® PLZ for EnterobacteralesEACAVery Major Error RateMajor Error RateMinor Error Rate99.0% (592/598)92.8% (555/598)1.9%(1/53)0.0%(0/478)7.0% (42/598)Table 2.MIC distribution BMD and ETEST® PLZ (mode MIC in bold)MIC/Interp µg/ml≤0.016S0.032S0.064S0.125S0.25S0.5S1S2S4I8R1R32R64R128R≥256RBMD000512217298816715710129ETEST® PLZ00055923293946511730030ConclusionETEST® PLZ clinical performance met the FDA acceptance criteria and was found useful for determining Plazomicin MIC of Enterobacterales, including ESBL, CRE (MBL, KPC, Oxa-48), high level AmpC and aminoglycoside resistant strains. Percent susceptibility of Plazomicin is at 80% among the 598 isolates tested, the mode MIC is 0.5 ug/ml as Susceptible.DisclosuresTom Armstrong, BS, bioMérieux (Employee) Laurine Blanchard, PhD, bioMérieux (Employee) Michael Kresken, PhD, bioMérieux (Scientific Research Study Investigator, Research Grant or Support) Gilles Zambardi, biomerieux (Employee) Marion Pompilio, BioMérieux (Employee)

The Analysis of Field Strains Isolated From Food, Animal and Clinical Sources Uncovers Natural Mutations in Listeria monocytogenes Nisin Resistance Genes.

Nisin is a commonly used bacteriocin for controlling spoilage and pathogenic bacteria in food products. Strains possessing high natural nisin resistance that reduce or increase the potency of this bacteriocin against Listeria monocytogenes have been described. Our study sought to gather more insights into nisin resistance mechanisms in natural L. monocytogenes populations by examining a collection of 356 field strains that were isolated from different foods, food production environments, animals and human infections. A growth curve analysis-based approach was used to access nisin inhibition levels and assign the L. monocytogenes strains into three nisin response phenotypic categories; resistant (66%), intermediate (26%), and sensitive (8%). Using this categorization isolation source, serotype, genetic lineage, clonal complex (CC) and strain-dependent natural variation in nisin phenotypic resistance among L. monocytogenes field strains was revealed. Whole genome sequence analysis and comparison of high nisin resistant and sensitive strains led to the identification of new naturally occurring mutations in nisin response genes associated with increased nisin resistance and sensitivity in this bacterium. Increased nisin resistance was detected in strains harboring RsbUG77S and PBPB3V240F amino acid substitution mutations, which also showed increased detergent stress resistance as well as increased virulence in a zebra fish infection model. On the other hand, increased natural nisin sensitivity was detected among strains with mutations in sigB, vir, and dlt operons that also showed increased lysozyme sensitivity and lower virulence. Overall, our study identified naturally selected mutations involving pbpB3 (lm0441) as well as sigB, vir, and dlt operon genes that are associated with intrinsic nisin resistance in L. monocytogenes field strains recovered from various food and human associated sources. Finally, we show that combining growth parameter-based phenotypic analysis and genome sequencing is an effective approach that can be useful for the identification of novel nisin response associated genetic variants among L. monocytogenes field strains.

Enterococcus faecalis Endocarditis and Outpatient Treatment: A Systematic Review of Current Alternatives.

The selection of the best alternative for Enterococcus faecalis infective endocarditis (IE) continuation treatment in the outpatient setting is still challenging. Three databases were searched, reporting antibiotic therapies against E. faecalis IE in or suitable for the outpatient setting. Articles the results of which were identified by species and treatment regimen were included. The quality of the studies was assessed accordingly with the study design. Data were extracted and synthesized narratively. In total, 18 studies were included. The treatment regimens reported were classified regarding the main antibiotic used as regimen, based on Aminoglycosides, dual β-lactam, teicoplanin, daptomycin or dalbavancin or oral therapy. The regimens based on aminoglycosides and dual β-lactam combinations are the treatment alternatives which gather more evidence regarding their efficacy. Dual β-lactam is the preferred option for high level aminoglycoside resistance strains, and for to its reduced nephrotoxicity, while its adaptation to the outpatient setting has been poorly documented. Less evidence supports the remaining alternatives, but many of them have been successfully adapted to outpatient care. Teicoplanin and dalbavancin as well as oral therapy seem promising. Our work provides an extensive examination of the potential alternatives to E. faecalis IE useful for outpatient care. However, the insufficient evidence hampers the attempt to give a general recommendation.

Tolerance Capacity of Chlamydomonas VHLR Mutants for the Toxicity of Mercury

The toxicity effect of metals on Chlamydomonas strains having a higher tolerance level for oxidative stress is important to investigate for better understanding their tolerance capacity. In this study, the toxicity of HgCl2 was determined on two very high light resistant (VHLR) mutant strains of Chlamydomonas, CC-3723 and CC-3724, and on the wild-type CC-125. All strains were exposed to 1–7 μM of HgCl2 during 24–72 h. The results showed that VHLR mutants were less affected by the effect of HgCl2 than CC-125, due to a better ability to detoxify the level of intracellular reactive oxygen species (ROS) generated by Hg. In particular, the effect of 3 μM of HgCl2 inhibited completely the growth rate of CC-125 at 24 h, which was correlated with a high accumulation of Hg and a strong level of ROS. From 48 to 72 h, the growth rate was recovered for all strains, which was stronger for VHLR mutants than the wild-type by 50% at 48 h, when compared to 24 h. In addition, the extracytoplasmic polyP level decreased significantly compared to the control for all strains treated to 3 μM of HgCl2 during 24–48 h. These results suggested that the polyP did participate to the tolerance for Hg through its cellular sequestration. Furthermore, the analysis of cellular morphology showed that VHLR mutants formed palmelloid colonies of 4–5 cells under 3 μM of HgCl2 at 48 h, reducing the surface contact with Hg. Therefore, VHLR mutants were more tolerant than the wild-type to the effect of low concentrations of HgCl2 (1 and 3 μM).

Multiphase characterization of wild Vigna associated root nodule bacteria from Japanese subtropical islands unveiled novel high temperature resistant Bradyrhizobium strains having high symbiotic compatibility with soybean and mungbean

ABSTRACT Vigna riukiuensis plant – a rare type of vigna, found only in Taiwan and the islands of Okinawa prefecture, Japan – possesses intrinsic property of high level of salt and heat tolerance. To understand the diversity and identify suitable rhizobia, multiphase characterization of root nodule bacteria associated with V. riukiuensis grown in Ishigaki and Iriomote Islands of Okinawa prefecture was performed. Multigene phylogenetic analysis of housekeeping genes based on 16S rRNA gene sequences, 16S-23S rRNA gene internal transcribed spacer (ITS) and 23S rRNA gene sequences identified three main groups closely similar to Bradyrhizobium japonicum, B. elkanii and B. jicamae family. However, analysis of symbiotic nifH and nodD1 genes and their phylogenetic trees showed similar topology, having only few discrepancies in comparison to the housekeeping gene phylogeny. Interestingly, for some of the isolates having similarity with B. elkanii, growth was observed at 40°C, which exceed the highest record for B. elkanii to the best of our knowledge. All the isolates were observed to have the capability of forming root nodules and fix nitrogen in their original host plant V. riukiuensis and two other crops: soybean and mungbean. Most of the isolates showed similar or higher nitrogen-fixing capability in comparison with B. diazoefficiens USDA110 in V. riukiuensis and V. radiata (mungbean), and Iri 5/6 in V. riukiuensis, Iri 5/12 in soybean and Ishi 7/2 in mungbean showed highest acetylene reduction assay (in µmol/h/gm nodule dry weight) activity, which was significantly higher than B. diazoefficiens USDA110. In addition, six isolates attained higher soybean biomass production compared with B. diazoefficiens USDA110, suggesting high symbiotic compatibility with soybean. Among them, Iri 5/7 of B. elkanii group contributed 29% higher soybean biomass production than B. diazoefficiens USDA110 and could grow at 40°C, hence it could be a promising soybean inoculant in the tropics. Abbreviations ARA: acetylene reduction assay, ISR: intergenic spacer regions, ITS: internal transcribed spacer

Detection of Oxacillin (Methicillin)-resistant Staphylococcus aureus Isolated from a Tertiary-care Hospital, Georgetown, Guyana

Background and Aim: Methicillin-resistant Staphylocccus aureus (MRSA) continues to be a major problem globally. Previous data had suggested that the prevalence of MRSA infections in the tertiary hospital setting was 51%. The aim of this study was to conduct a point prevalence survey of MRSA infections occurring at a tertiary-care hospital in Georgetown, Guyana, and to determine to what extent methicillin-resistance was occurring among Staphylococcus aureus isolates utilising the minimum inhibitory concentration (MIC) data.&#x0D; Study Design: This study was based on a prospective, analytical design.&#x0D; Place and Duration of Study: Microbiology department, Georgetown Public Hospital Corporation (GPHC), and Department of Medical Technology, University of Guyana, between May 2019 and July 2019.&#x0D; Methodology: A total of 101 consecutive, non-repetitive, laboratory-identified MRSA and methicillin-susceptible Staphylococcus aureus (MSSA) isolates were tested using an oxacillin broth microdilution method.&#x0D; Results: We found that 65.4% of Staphylococcus aureus were oxacillin (methicillin) resistant with a majority of the isolates being high level oxacillin resistant strains (i.e., MICs &gt; 256 μg/ml) (84.85%). Most of the resistant isolates were collected from patients admitted to medical and surgical wards. Conclusion: Methicillin-resistance continues to be a major problem in the hospital setting and conventional techniques are unlikely to identify all of the potentially resistant isolates.