International Journal of Microbiology最新文献

The Brazilian savannah, Cerrado, a Brazilian phytophysiognomy, is an entire biome that contains as well as other Brazilian ecosystems, a vast biodiversity of microorganisms associated with native plants. Plant species of the Cerrado have attracted attention due to the still limited knowledge regarding their associated microbiota and the possible applications of these microorganisms. Considering that wildflowers are rich reservoirs of yeast diversity, the present study isolated 58 yeast strains from flowers of Qualea grandiflora from two areas of Cerrado sensu stricto in northern Minas Gerais, Brazil. The isolates were evaluated for producing extracellular enzymes in cellulase, amylase, xylanase, protease, tannase, and pectinase tests. We used the YNB agar diffusion method (Difco) supplemented with specific substrates for each enzyme. The strains were identified by analyzing the sequences of the D1/D2 region of the large subunit (26S) rRNA gene and compared to the sequences deposited on GenBank. Fifty-eight strains were isolated, and 14 genera were identified, of which 18 species were yeasts, two species were yeast-like fungi, and three were yeast-like strains to which it was not yet possible to assign the species they belonged to. Among the identified species, the phylum Ascomycota predominated; exceptions were the isolates of the yeast Papiliotrema laurentii and the fungus Anthracocystis heteropogonicola, both belonging to the phylum Basidiomycota. In the enzymatic tests, 44.8% of the strains tested presented an enzymatic profile in solid medium, being capable of producing at least one of the enzymes studied, with the species Coniochaeta rhopalochaeta showing the greatest cellulolytic activity.

Acinetobacter baumannii, an opportunistic pathogen, is responsible for a wide range of healthcare-associated infections (HAIs), particularly in patients in intensive care units (ICUs). Carbapenem-resistant A. baumannii (CRAB) is of particular concern due to its extensive multidrug resistance (MDR) and limited treatment options. In Vietnam, CRAB has become increasingly prevalent, with resistant mechanisms primarily attributed to the presence of blaOXA-23 and blaNDM-1 genes. This study investigates the clinical characteristics and genomic epidemiology of three CRAB isolates (ICU773, ICU400, and ICU399) from a tertiary-care hospital in Ho Chi Minh City. The isolates exhibited high resistance to a wide range of antibiotics, including carbapenems, aminoglycosides, and fluoroquinolones, while maintaining susceptibility to colistin. Whole-genome sequencing was used to analyze the genomic profiles, resistance genes, and sequence types of the isolates. All three isolates possessed blaOXA-23 and additional resistance genes such as blaADC and aminoglycoside-modifying enzymes (AMEs). MLST analysis revealed distinct genetic lineages, with ICU773 and ICU400 belonging to Sequence Types 2/195 and 2/Novel and ICU399 to Sequence Types 571/804. In silico analysis further identified several efflux pump genes and other resistance mechanisms, including the presence of the adeABC, adeFGH, and AbaQ pumps. These findings highlight the complexity of CRAB's genomic diversity and resistance mechanisms in the region, underscoring the urgent need for continuous surveillance and novel therapeutic strategies to combat this growing healthcare threat.

Background: Clinically challenging bacterial infections are caused by microorganisms producing extended-spectrum β-lactamases (ESBLs), AmpC β-lactamase (AmpC), and carbapenemases, which confer antibiotic resistance and may result in treatment failure. This study was aimed at determining the prevalence of ESBL, AmpC, and carbapenemase-producing clinical isolates of Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Methods: This study was a cross-sectional study. A total of 362 isolates of E. coli, K. pneumoniae, and P. aeruginosa from urine, blood, pus, sputum, swab, and endotracheal (ET) tube tips were obtained from patients attending Manipal Teaching Hospital, Pokhara, Nepal, during March 2022 to October 2022. Phenotypic confirmation of ESBL, AmpC, and carbapenemase was done by combined disk test and modified Hodge test. Results: The prevalence of ESBL among isolates was found to be 58.3%. Confirmative tests showed 65.3% P. aeruginosa, 30.2% K. pneumoniae, and 17.7% E. coli were AmpC producers. Among the carbapenem-resistant isolates, 81.7% showed phenotypic evidence of carbapenemase production based on the modified Hodge test. Additionally, 9.9% and 5.2% of isolates demonstrated phenotypic characteristics suggestive of metallo-β-lactamase (MBL) and Klebsiella pneumoniae carbapenemase (KPC) activity, respectively. Conclusion: The ESBL production was the predominant mechanism of resistance to β-lactam drugs, followed by AmpC and carbapenemase production. Routine identification and monitoring of these organisms, followed by detection of β-lactamase production, optimize the effective management and prevention of antimicrobial resistance.

Two distinct types of human immunodeficiency virus (HIV), namely, HIV-1 and HIV-2 exist. HIV-1 is responsible for the global pandemic and has an aggressive pathogenesis. On the contrary, HIV-2 is not only less aggressive but also confined to West and Central African regions. Even after four decades of HIV research, a scalable cure or effective vaccine against HIV remains elusive. Consequently, the concept of a functional cure or vaccine, targeting to limit disease progression, allowing sufficient time for the immune response to clear the virus, has gained traction. Efforts to identify new therapeutic targets for development of a functional cure have focused on elite controllers, that is, individuals who naturally control HIV-1 infection in the absence of antiretroviral therapy. However, little progress has been associated with these efforts perhaps due to the scarcity of elite controllers, who make up only 0.15% of HIV-1 infected population globally. A distinct but largely unexplored subset of HIV patients comprise HIV-1 and HIV-2 dually infected individuals. This group of patients naturally presents with an attenuated disease progression phenotype akin to natural controllers. In this review, we discuss the attenuated disease progression phenomenon in dually infected individuals and offer potential explanations for this unanticipated observation. Additionally, we propose potential therapeutic and/or vaccine strategies that could leverage interactions of HIV-1 and HIV-2. Such strategies are likely to inform alternative therapeutics. A thorough understanding of the mechanism underlying the attenuated disease progression phenotype in HIV dually infected individuals is crucial for the design of a functional cure.

Introduction: Screening donated blood for transfusion-transmitted infections (TTIs) is a critical component of transfusion safety, particularly in high-demand regions such as Makkah City, Saudi Arabia. This study is aimed at assessing the seroprevalence of TTI markers among blood donors at King Abdulaziz Hospital-Makkah (KAHM) over a 7-year period. Methods: In this retrospective study, 17,661 individuals who donated blood at the KAHM, Saudi Arabia, from January 2017 to December 2023, were included. The prevalence of TTI markers was assessed and categorized by year, gender, age, type of donors (whole blood and apheresis), and category of donation (replacement and volunteer). In addition to ABO group testing, commercially available kits were used for serological tests. Results: Among donors, 74 (0.42%) were reactive for HBsAg, 1419 (8.03%) for HBcAb, and 1295 (7.33%) for HBsAb. Other reactive cases included HCV (0.29%), HIV (0.06%), HTLV-I/II (0.05%), and syphilis (0.44%). No cases of malaria were reported. Statistically significant variations were observed across years for HBsAg (p = 0.007), HBsAb, and HBcAb (p < 0.001), suggesting changes in infection exposure, immunity, or donor screening efficiency. Male donors represented 97.17% of the cohort, and replacement donors were more prevalent (54.75%) than volunteers. Conclusion: The overall prevalence of TTIs among blood donors in Makkah was low, affirming the effectiveness of current screening protocols. However, the relatively high prevalence of hepatitis B core antibodies indicates prior exposure among a notable proportion of donors. Yearly fluctuations in seropositivity suggest evolving epidemiological patterns, warranting continuous surveillance and targeted public health interventions.

Trypanosoma cruzi is the causative agent of Chagas disease and is capable of invading any nucleated cell in the vertebrate host. The parasite utilizes various virulence factors during cell invasion, including the P21 protein. P21 is encoded by a single-copy, nonconserved gene expressed across all T. cruzi life cycle stages. Its sequence codes for a protein implicated in cell invasion and parasite multiplication. Given the significant differences in biological behavior between distinct strains of T. cruzi, we ablated the P21-coding gene in two phylogenetically distant strains (G and Y strains) and assessed its impact on the transcriptome profile of intracellular amastigotes. Our findings revealed that P21 depletion affected the transcription of different genes in the G and Y strains, with each strain exhibiting enrichment for distinct biological processes. Notably, protein translation was the major biological process impacted by P21 depletion, showing upregulation in the G strain and downregulation in the Y strain. In conclusion, our findings demonstrate that P21 gene ablation induces strain-specific transcriptional reprogramming in T. cruzi amastigotes, revealing divergent roles for P21 in modulating fundamental cellular processes like protein translation and potentially influencing host-parasite interactions, contingent upon the parasite's genetic background.

Vatica diospyroides, an endemic species of the Dipterocarpaceae family, possesses notable medicinal properties. However, its application as an antibacterial agent is limited due to the insufficient investigations of its antibacterial activity from flower extracts. This study is aimed at exploring the antibacterial mechanisms of acetone extracts from the flowers of V. diospyroides against four bacterial strains using various methods, including the well-disk diffusion assay, minimum inhibitory concentration (MIC) determination, minimum bactericidal concentration (MBC) assessment, flow cytometry, and scanning electron microscopy. The inhibition zones measured between 6.33 and 17.66 mm. Notably, the extract exhibited different MIC values, such as 250 μg mL^-1 for Bacillus subtilis and Escherichia coli, and only 62.5 μg.mL^-1 for Vibrio parahaemolyticus, demonstrating its effectiveness. MBC values ranged from 500 to over 1000 μg mL^-1 for Pseudomonas aeruginosa. Flow cytometric analysis revealed that the cellular responses to the extract were influenced by both the concentration of the extract and the duration of exposure, indicating a dose- and time-dependent antibacterial effect. Additionally, scanning electron microscopy confirmed that the extract caused structural damage to the cells of both Gram-positive and Gram-negative bacteria. Overall, this study underscores the promising antibacterial potential of V. diospyroides flower extracts, which demonstrate significant efficacy against a variety of bacterial strains.

This study investigates the effectiveness of a disinfectant formulation comprising acetic acid, hydrogen peroxide, and peracetic acid (AAHPA) against Aspergillus niger, Escherichia coli, and Staphylococcus aureus on petri plates, smooth surfaces, and rough surfaces. Comparative analysis with conventional disinfectants such as 70% isopropyl alcohol, 1.5% chlorhexidine gluconate, 10% sodium hypochlorite, and 0.2% hydrogen peroxide reveal AAHPA's superior performance, achieving significantly higher log reduction (p < 0.05) and percentage reduction (p < 0.01) against A. niger in 5 min on petri plates. On smooth and rough surfaces, AAHPA exhibits exceptional efficacy, demonstrating the highest log and percentage reduction against A. niger in 0.5, 1, and 5 min, surpassing other disinfectants. AAHPA shows the highest bacterial decline against E. coli and S. aureus, followed by 0.2% hydrogen peroxide. In some cases, 0.2% hydrogen peroxide was slightly more effective than AAHPA against E. coli and S. aureus in 5 min. Time-dependent analysis of log reduction trends emphasizes AAHPA's rapid and consistent effectiveness, particularly in 0.5 min, positioning it as a promising disinfectant formulation with broad-spectrum efficacy across diverse surfaces.

Ticks, particularly Ixodes ricinus, are significant vectors of pathogens such as Borrelia spp. and tick-borne encephalitis virus (TBEV), which cause Lyme borreliosis (LB) and tick-borne encephalitis (TBE), respectively. Understanding how these pathogens interact within the tick microbiome is essential for developing vector control strategies. This study investigates the impact of Borrelia afzelii and TBEV, as well as their coinfection, on the microbiota composition and structure of I. ricinus nymphs. Using a network-based approach, we analyzed the microbial communities of ticks exposed to infected or coinfected mice. DNA extracted from newly molted nymphs was sequenced for the bacterial 16S rRNA gene, and microbial diversity metrics (alpha and beta diversity) were calculated. Our results showed that TBEV infection increased microbiome diversity compared to the uninfected and Borrelia groups. Co-occurrence network analyses revealed that while microbial structures remained consistent across conditions, TBEV-infected networks exhibited higher robustness to perturbations, indicating a stabilizing effect on the tick microbiome. Furthermore, the hierarchical position and associations of Borrelia varied significantly depending on the infection scenario, highlighting its adaptive role within the tick microbiota. The study demonstrates that pathogen presence alters tick microbial dynamics, with TBEV enhancing stability, suggesting virus-mediated modifications of the microbiome. These findings advance our understanding of pathogen-tick-microbiome interactions and provide insights into the ecological mechanisms underlying pathogen coexistence within ticks. This research underscores the importance of microbial networks in ticks and offers new perspectives for targeted approaches in managing tick-borne diseases.

Diarrheal infections, a leading cause of global morbidity and mortality, are frequently attributed to pathogenic Escherichia coli strains. The rise of antibiotic resistance among these pathogens necessitates the exploration of alternative therapeutic agents. This study is aimed at evaluating the Rose Bengal effect to fight antibiotic resistance in pathogenic E. coli. Using a combination of in vitro assays-including microbiological isolation, 16S RNA molecular identification, acid resistance testing, biofilm and swarming assays, hemolytic activity evaluation, and antibiograms-and in vivo analysis with Rhynchophorus phoenicis larvae, 22 E. coli isolates were obtained. Molecular analyses identified four pathogenic strains: KNH8 (PQ864811), KNH11 (PQ864812), KNH14 (PQ864813), and KNH16 (PQ864814), classified as enterotoxigenic E. coli (ETEC) and enteropathogenic E. coli (EPEC). Pathogenicity assessments revealed that Rose Bengal (200 μM) significantly reduced acid and bile salt resistance, biofilm formation, swarming motility, and hemolytic activity in all strains. Furthermore, Rose Bengal enhanced the sensitivity of these strains to five antibiotics-imipenem, kanamycin, chloramphenicol, gentamicin, and amoxicillin/clavulanic acid (AMC)-with increases ranging from twofold to sixfold in pathogenic strains (KNH8, KNH11, KNH14, and KNH16). These effects were further corroborated by in vivo testing using R. phoenicis larvae. The findings highlight the virulent potential of these E. coli strains and suggest Rose Bengal as a promising antimicrobial agent against multidrug-resistant pathogens.