Brazilian Journal of Microbiology最新文献

Hantaviruses that infect humans are rodent-derived viruses with zoonotic potential. Several studies show that before emerging in rodents hantaviruses could emerge in bats, which makes it important to study bat-derived hantaviruses. In this study, we performed PCR screening of hantaviruses in samples from common noctules (Nyctalus noctula [182 fecal and 81 blood serum samples]), parti-coloured bats (Vespertilio murinus [41 fecal samples]), Kuhl's pipistrelles (Pipistrellus kuhlii [15 fecal samples]), and serotine bats (Eptesicus serotinus [8 fecal samples]) from Rostov Bat Rehabilitation Center (Rostov-on-Don, Russia) and phylogenetic analysis of detected viruses. As a result, hantaviruses were detected in samples from N. noctula bats with an overall prevalence of 4.94% (4/81, 95% CI 0.22-9.66%) in blood serum samples and 1.1% (2/182, 95% CI 0-2.61%) in fecal samples. Phylogenetic analysis revealed that detected hantaviruses are highly homologic to Brno loanviruses (Loanvirus brunaense) previously discovered in N. noctula bats from Central Europe, which brings some evidence that these are the same bat-derived viruses. This study shows that Loanvirus brunaense could be species-specific to the host and has a wide area of habitat: from Central Europe to Southern Russia. These are the first findings of this virus in Southern Russia and Ciscaucasus/Fore-Caucasus. Further studies with wider screening and genomic assays of Loanvirus brunaense in bats could reveal trends in the molecular evolution of hantaviruses and provide valuable data for the control of potential spillovers.

Magnetotactic bacteria align to magnetic field lines while swimming in a behavior known as magnetotaxis. They are diverse phylogenetically and morphologically and include both unicellular and multicellular morphologies. The magnetotactic multicellular prokaryote (MMP) 'Candidatus Magnetoglobus multicellularis' has been extensively studied, even though it remains uncultured up to now. It swims back and forth along magnetic field lines, exhibiting a preferential swimming direction that is usually south-seeking, as described for most magnetotactic microorganisms from the Southern Hemisphere. In order to understand the effects of the magnetic field intensity on the backward excursions of 'Ca. M. multicellularis', we applied magnetic fields ranging from 0.09 to 3.4 mT and recorded their movements. Each microorganism was followed frame by frame generating position coordinates, which were used to calculate the frequency of reversal events, as well as the time, distance, and velocity. The velocities in forward movements before and after backward excursions are similar, but no relation was found with the velocity in backward movements. The shapes of the trajectories are distinct in forward and backward movements. In addition, the backward velocities are usually higher. The sharp changes in direction (approximately 180°) indicate that reversal of the flagella rotation direction is the probable mechanism for swimming backward. In conclusion, the backward excursions provide additional freedom of movement to the microorganism, especially when it is constrained by magnetic fields stronger than the Earth's. Backward movements integrate the 'Ca. M. multicellularis' behavioral toolbox, which includes also negative phototaxis, photokinesis, magnetotaxis and possibly helical klinotaxis.

Introduction: Helicobacter pylori (H. pylori) is a major human pathogen whose increased antibiotic resistance poses a serious threat to human health.

Aim: The aim of this study is to further explore the association between H. pylori resistance to clarithromycin, levofloxacin, metronidazole, amoxicillin, rifampicin, tetracycline and its genomic characteristics.

Methodology: Using H. pylori isolates, we studied their susceptibility to six antibiotics by the agar dilution method. By performing whole-genome resequencing of the H. pylori genomic DNA, the differences in single nucleotide polymorphisms (SNPs) between phenotype resistant and sensitive strains were statistically analyzed to identify potential mutation sites related to drug resistance, and the consistency between genotype and phenotype resistance was analyzed.

Results: The drug resistance rates of 65 H. pylori isolates are as follows: clarithromycin 36.9%, levofloxacin 29.2%, metronidazole 63.1%, amoxicillin 7.7%, rifampicin 12.3%, and tetracycline 3.1%. Based on the whole genome resequencing results of H. pylori isolates, 10 new mutations that may be related to drug resistance were identified. There is strong consistency between the genotype and phenotype resistance of clarithromycin and levofloxacin.

Conclusion: The resistance rate to amoxicillin and tetracycline is relatively low in Northern China. and the above two antibiotics can be given priority for clinical treatment. It has a high resistance rate to metronidazole and should be avoided as much as possible, or combined with other drugs for treatment. The 10 mutations identified through analysis that only exist in drug-resistant strains may be associated with levofloxacin, metronidazole, amoxicillin, and rifampicin resistance, respectively. The results indicate that genotype testing of H. pylori can serve as a method for predicting its resistance to clarithromycin and levofloxacin.

Among the Candida species commonly involved in superficial and more significant life-threatening infections, C. krusei exhibits the most worrisome resistance profile to antifungals. This study aimed to analyse the population structure using multilocus sequence typing (MLST), and to evaluate the antifungal susceptibility profile of C. krusei isolated from patients living with human immunodeficiency virus (HIV) in Cameroon. C. krusei isolated from stool, urine, mouth and vaginal samples were identified using routine laboratory techniques and matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS). The C. krusei isolates were further analysed by MLST. In vitro antifungal susceptibility testing was performed using the Sensititre Yeast One™ microdilution technique. Forty three (43) C. krusei isolates were included in the study. The MLST identified 32 Diploid sequence type (DST), of which 31 were new that were not included in the current database. New alleles were not observed. Different DSTs were observed in isolates from the same geographical area, from different anatomical sites in the same patient. An eBURST analysis clustered all identified DSTs of former isolates in clonal complex 1. Heterogeneous antifungal MICs were observed in isolates of the same DST and/or from the same geographical area. 32.6% of the isolates displayed a resistant or non-wild-type phenotype to at least 3 distinct antifungal agent classes. The achieved results support the setting up of molecular epidemiology and antifungal resistance surveillance of C. krusei.

Antibiotic resistance and the potential persistence of Klebsiella pneumoniae strains in hospital environments is an important challenge for human medicine. This research aims to detect resistance to antibiotics, biofilm formation, and the genetic pattern among clinical isolates associated with nosocomial infection obtained from a university hospital in the city of Pelotas, RS, Brazil. Twenty-eight isolates were identified at the species level by polymerase chain reaction (PCR) and were characterized regarding the profile of biofilm formation and antibiotic resistance. The genetic relationship was determined through pulsed-field gel electrophoresis (PFGE). The antibiotic resistance profile was made following the standards established by CLSI. All clinical isolates included in this study were confirmed as belonging to the species K. pneumoniae, 96.42% were considered strong biofilm formers and all were positive in the Congo Red agar (CRA) test. Thus, 64.29% of isolates were classified as multidrug-resistant (MDR), 25% as extensively drug-resistant (XDR), and 7.14% as pandrug-resistant (PDR). PFGE fingerprint analysis revealed 18 clones and of these, 15 have a unique pattern and another three were groups with patterns > 80% similarity. The clinical isolates used were collected over two years and revealed a genetic relationship. The same clone was identified in different types of samples and different years, demonstrating the permanence of the strain in the hospital environment. Our results reaffirm the need for greater measures of control and disinfection within the hospital environment, and the priority of therapeutic measures to contain the propagation of K. pneumoniae.

The phytopathogenic oomycete Phytopythium helicoides, previously known as Pythium helicoides, has emerged as a new threat to the Shatangju citrus cultivar (Citrus reticulata cv. Shatangju; '' in Chinese) in southern China. To enable rapid diagnosis and control of the leaf blight and stem rot caused by P. helicoides, we developed a visualized loop-mediated isothermal amplification (LAMP) assay targeting the β-tubulin gene of the pathogen. Using a carefully selected set of primers and optimized reaction conditions at 60 °C for 60 min, the LAMP assay can specifically detect the pathogen among various citrus-associated phytopathogens. The assay demonstrated high sensitivity, detecting as little as 30 pg of the pathogen DNA, comparable to the sensitivity of quantitative polymerase chain reaction (qPCR). We validated the practical application of this LAMP assay for diagnosing infections in citrus leaves and strawberry crowns. This newly developed LAMP assay offers a specific, sensitive, and rapid detection tool for P. helicoides, aiding in the control of Shatangju citrus leaf blight and stem rot, as well as other related crop diseases like strawberry crown rot.

This study analyzes the resistance and virulence profiles of Proteus mirabilis isolates obtained from patients admitted to the University Hospital of Londrina, Paraná, between 2019 and 2022. We evaluated the antimicrobial resistance phenotypes, genes associated with resistance, biofilm formation through a phenotypic assay, and the presence of specific virulence genes. When comparing the "pre-pandemic" (2019) and "pandemic" (2020-2022) periods, we observed an increase in resistance rates to all tested antimicrobials. Multidrug-resistant (MDR) pathogens producing extended-spectrum β-lactamase (ESBL) phenotypes were isolated in both periods, but their occurrence was significantly higher during the pandemic. We also observed an increase in the frequency of nearly all studied resistance genes. The virulence profiles remained largely unchanged. Analysis of patients' clinical and demographic data revealed that those hospitalized during the pandemic were older, required longer hospital stays, and had a higher usage of invasive devices. These findings suggest that the recent COVID-19 pandemic has impacted the antimicrobial resistance of P. mirabilis, a bacterium of significant clinical interest associated with urinary tract infections (UTIs) and healthcare-associated infections (HAIs).

The disposal of fat, oil, and grease (FOG) pollutants from various sources, including restaurants, food processing facilities, and domestic kitchens, poses significant challenges to wastewater treatment systems. In this study, we isolated and characterized a novel bacterial strain. The result of 16 S rRNA gene and phylogenetic analysis showed that the isolate was Staphylococcus petrasii sub sp. jettensis and named as VSJK R1 (Fig. S1). It was tested for its biodegradation potential of FOG contaminants. Our investigation revealed that Staphylococcus petrasii sub sp. jettensis VSJK R1 effectively degraded a variety of edible oils, including soybean, sunflower, cottonseed, palm, groundnut, and butter, with notable efficiency. Optimization studies were conducted to determine the optimal conditions for biodegradation, including the effects of nitrogen, carbon, phosphorus, pH, temperature, and salt concentration. Results indicated that organic nitrogen sources and glucose as carbon source significantly enhanced biodegradation rates, while the addition of phosphorus further improved degradation efficiency within specific concentration ranges. Moreover, the optimal pH for biodegradation was found to be neutral, with temperature ranging between 22°C and 45°C favoring microbial activity. Remarkably, Staphylococcus petrasii sub sp. jettensis VSJK R1 exhibited resilience to high salt concentrations, making it suitable for treatment of wastewater with elevated salt content. Additionally, comparative studies with other microbial strains underscored the unique biodegradation capabilities of Staphylococcus petrasii sub sp. jettensis VSJK R1, particularly in degrading various edible oils. The results suggest promising applications of this novel isolate in bioremediation efforts targeting FOG pollutants in wastewater treatment plants and grease traps. Future research may focus on scaling up the bioremediation process and field testing the efficacy of Staphylococcus petrasii sub sp. jettensis VSJK R1 in real-world wastewater treatment scenarios.

This study details the synthesis and optimization of extracellular inulinase through solid-state fermentation using improved strain of Rhizopus oligosporus. The wild-type was procured from IIB culture bank and subsequently enhanced through UV-radiation and Nitrous acid treatments. The resulting mutant strain was subjected to further optimization for heightened enzyme production via solid-state fermentation. The substrate, pressmud (20 g), and moisture content (20 mL molasses) were carefully selected. Key parameters such as inoculum size, incubation time, and inulin concentration were optimized to maximize enzyme yield. Mutation procedures involved optimizing spore suspension, UV-radiation exposure duration, and the distance of culture plate from UV rays. Nitrous acid treatment, followed by resistance development using L-cysteine HCl, further refined the mutant strains. Evaluation through UV-Vis spectrophotometry and comprehensive characterization using SEM, FTIR, and XRD were conducted to compare the results between the wild-type and mutant strains. The mutant strain exhibited significantly higher inulinase activity (111 ± 0.49 U/ml) as compared to its wild-type counterpart (59 ± 0.65 U/ml), indicating successful enhancement through the applied mutation techniques. The molecular weight of the inulinase enzyme produced from mutant strain and wild-type was 83 and 86 kDa respectively. These findings suggest potential industrial applications of the improved strain in various biotechnological processes.