Brazilian Journal of Microbiology最新文献

Chlamydias are zoonotic pathogens, broadly present in several bird species and responsible for economic losses in animal production. Our study focused on assessing the prevalence of Chlamydial species posing zoonotic risks in farm animals within the highly biodiverse Argentine, Brazil, and Paraguay tri-border area, characterized by significant human interaction. We surveyed nine farms in an area and nasally swabbed a total of 62 animals, that included cattle, horses and pigs. DNA was extracted and specific PCR was performed to identify and sequenced chlamydial species. We detected Chlamydia spp. in 6.5% (4/62) of the tested animals, with all positive cases found in cattle. None of the cattle showed symptoms of respiratory disease or had been diagnosed with reproductive disorders. Specific nested PCR confirmed two samples belonged to Chlamydia pecorum and two to Chlamydia psittaci. We report for the first time Chlamydia circulation with zoonotic risk in the region. We propose that surveys in birds and wild mammals could give a better understanding to know what Chlamydial species are circulating in the wild interface. The zoonotic potential should be taking into account as farm workers and the surrounding population could be silent carriers or have respiratory diseases being underdiagnosed, and therefore should be considered in the differential diagnoses.

The intestinal microbiota is widely recognized as an integral factor in host health, metabolism, and immunity. In this study, the impact of dietary fiber sources on the intestinal microbiota and the production of short-chain fatty acids (SCFAs) was evaluated in Lohmann White laying hens. The hens were divided into four treatment groups: a control diet without fiber, a diet with wheat bran (mixed fibers), a diet with insoluble fiber (cellulose), and a diet with soluble fiber (pectin), with six replicates of four hens each. Cecal content from 24 hens was analyzed using 16 S rRNA sequencing, while SCFA concentrations were measured in blood serum. Alpha diversity analysis revealed significant variations in microbial richness and diversity among treatments, with higher species richness observed in hens fed wheat bran and cellulose, as indicated by Shannon indices. Principal Coordinates Analysis (PCoA) showed significant differences in microbial composition between the control group and the fiber-supplemented groups. The predominant phyla were Bacteroidetes, Campilobacterota, Firmicutes, and Spirochaetota, with a notable increase in Bacteroidetes in fiber-supplemented groups. Regarding SCFAs, fiber inclusion increased acetic and propionic acid concentrations compared to the control group. Diets with mixed fibers (wheat bran) resulted in the highest acetic acid levels, while propionic acid was most abundant in hens fed soluble fiber (pectin). These findings demonstrate that dietary fiber inclusion to laying hens enhances microbial diversity, stimulates SCFA production, and contributes to host metabolism and health.

Failures in endodontic treatments are common due to microbial resistance in the pulp canal. The study evaluated the in vitro activity of polyhexamethylene guanidine hydrochloride (PHMGH) against endodontic strains, as well as in vivo toxicity. Using minimum inhibitory concentration and minimum bactericidal concentration techniques, PHMGH was effective against all microorganisms, even at low concentrations. At 50.0 µg/mL, it inhibited Enterococcus faecalis; furthermore, when compared to chlorhexidine (CLX), it demonstrated values 19 times lower against Candida albicans. The polymer's activity was also determined by agar diffusion, evaluating products A (calcium hydroxide - Ca(OH)2, as a reference), B (Ca(OH)2 combined with physiological solution, reference with a vehicle), C (PHMGH 6.25%), D (PHMGH 3.125%), E (PHMGH 1.5625%), F (PHMGH 0.78125%), G (PHMGH 6.25% and Ca(OH)2), H (PHMGH 3.125% and Ca(OH)2), I (PHMGH 1.5625% and Ca(OH)2), J (PHMGH 0.78125% and Ca(OH)2), and K (positive control, CLX 0.12%). Products containing PHMGH were more effective than the references against all strains, and C, D, and G were more effective than CLX against Peptostreptococcus anaerobius, Actinomyces naeslundii, and Actinomyces viscosus. According to the fractional inhibitory concentration index, the combination of PHMGH and CLX showed indifference for Peptostreptococcus anaerobius, Actinomyces naeslundii, Actinomyces viscosus and Escherichia coli, antagonism for Candida albicans, and synergy for Enterococcus faecalis. The toxicity of PHMGH at different concentrations was tested in Caenorhabditis elegans and did not show lethality in nematodes, with the LC50 observed only at the highest concentration (100 µg/mL) after two days of exposure. It is suggested that PHMGH exhibited antimicrobial activity against endodontic strains and low toxicity, raising expectations for new preventive and therapeutic products in endodontics.

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.

In this study water samples were investigated for the presence of heavy metals and pesticide resistance in Escherichia coli (E. coli) collected from district Jhal Magsi. Identification of E. coli was carried out via Polymerase Chain Reaction (PCR) assays. Heavy metals and pesticide resistance were conducted by the Kirby-Bauer disk diffusion method. E. coli was confirmed by using uidA (623 bp) and usp (515 bp) genes primer. A relatively high resistance rate was observed for Cd and DDT (2, 4 D) with 100% at the concentration of 1600 µl/mL. Samples showed the resistance pattern for Cr with 55% and sensitivity was 45% at 800 µl/mL. Resistance and sensitive percentage of Pb, Co were observed 61, 63, and 39, 37% at 400 µl/mL. Cyanazine resistance and the sensitive percentage were 51 and 49% at 800 µg/mL. For Chlorpyrifos and Carbofuran, 54 and 65% resistance and sensitivity 46 and 35% were measured at a lower range of 400 µl/mL. Excessive use of heavy metals and pesticide pollution in standing water near agriculture fields contributed to accelerating the abundance of multi-pollutant-resistant E. coli in water that could be useful in the bioremediation of pesticides and heavy metals.

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).

Pythiosis, caused by Pythium insidiosum, is an infectious and non-transmissible disease affecting horses, dogs, and humans, with no effective drug treatment available. Triazoles are compounds of interest for their potential pharmacological properties against fungi and bacteria. In this study, we synthesized three new triazole compounds (C1, C2, and C3) to assess their in vitro activities against P. insidiosum and their safety on human leukocytes. Susceptibility testing was performed against P. insidiosum isolates (n = 15) to determine the minimum inhibitory concentration (MIC) and minimum oomicidal concentration (MOC). The leukocyte toxicity of triazoles was evaluated by measuring cell viability, morphological aspects, and oxidative stress endpoints. In silico prediction of the compounds absorption, distribution, metabolism, excretion and toxicity (ADMET) was determined using the pkCSM platform. Both triazoles C1 and C2 exhibited anti-Pythium insidiosum activity at concentrations from 2 to 64 µg/mL to MIC and MOC, while C3 MIC was 4-64 µg/mL and MOC 8-64 µg/mL. The three compounds did not induce viability loss and/or morphologic changes to human leukocytes, and showed absence of a pro-oxidant profile. ADMET properties prediction of the compounds was similar to the reference drug fluconazole. This study introduces novel triazole compounds exhibiting anti-P. insidiosum activity at concentrations non-toxic to human leukocytes.

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.

Porcine reproductive and respiratory syndrome (PRRS) is a significant swine disease with no effective vaccine due to high viral mutation rates. This study investigates a natural PRRS outbreak through molecular, pathological, and serological analyses. Nineteen affected pigs were clinically examined, and 10 underwent post-mortem examination. PRRS virus (PRRSV) presence was confirmed in all tissue samples by RT-PCR targeting open reading frame (ORF) 5 and ORF7 genes. Clinical signs, especially in boars and sows, included fever, appetite loss, movement reluctance, erythematous skin patches, vomiting, and abortions in sows. Post-mortem findings highlighted lung consolidation, severe lymph node enlargement, interstitial pneumonia with mononuclear cells, macrophage accumulation and necrotic cells in alveolar spaces. Multifocal myocarditis, lymphoid follicular degeneration, and follicular necrosis were observed in the tonsil, spleen, and lymph nodes. PRRSV-specific antibodies were detected in 32.75% of serum samples, confirming the outbreak. Phylogenetic analysis of the PRRSV-ORF5 and ORF7 genes revealed a close genetic relationship between the outbreak samples from Assam and recent outbreaks in Idukki, Kerala, India (2018), and neighbouring country China, indicating the circulation of Genotype 2 virus in Assam. However, the sequences showed some differences from the isolates of Mizoram, India. In conclusion, this study provides molecular and pathological evidence of a PRRSV outbreak, confirms the presence of PRRSV-specific antibodies and viral RNA, and shed light on the virus's genetic characteristics in India.