International Journal of Microbiology最新文献

The increasing threat of antimicrobial resistance (AMR) highlights the urgent need for alternative therapeutic strategies, particularly those targeting microbial virulence factors like biofilm formation. This study aimed to isolate and identify Streptomyces species with potential antibiofilm activity against clinically relevant biofilm-producing bacterial pathogens. Actinomycetes were isolated from soil samples, cultured on Gause's synthetic agar (GSA) and identified through 16S rRNA gene sequencing. Clinically isolated pathogenic bacteria, including Proteus mirabilis, Escherichia coli, Klebsiella oxytoca, Acinetobacter baumannii, and Klebsiella pneumoniae, were identified using the VITEK 2 system. The antibiofilm and antibacterial activities of the bioactive compounds extracted from Streptomyces spp. were assessed using the agar plug diffusion method and quantitative biofilm assays with crystal violet staining. Among the isolated Streptomyces strains, Streptomyces albogriseolus was identified as a promising producer of bioactive metabolites. The isolate exhibited 99% similarity to strain NBRC 3709 based on 16S rRNA gene sequencing. The crude extract at a concentration of 20 mg/mL demonstrated significant antibacterial activity, with inhibition zones of 11.9 mm against K. pneumoniae and 15.1 mm against E. coli. Moreover, the extract significantly reduced biofilm formation in A. baumannii and E. coli. A lower antibiofilm effect was also observed against K. pneumoniae, P. mirabilis, and K. oxytoca, with K. oxytoca exhibiting the weakest biofilm inhibition. In conclusion, secondary metabolites from S. albogriseolus display significant antibiofilm activity against drug-resistant pathogens, with efficacy varying by bacterial species and extract concentration. These findings underscore the potential of Streptomyces-derived metabolites as promising candidates for combating biofilm-associated infections. Further studies are recommended to explore their mechanism of action and optimize their potential therapeutic application.

Different factors, including microbial resistance, have led to food contamination and increased human intoxication risks. Therefore, finding new adequate methods to fight against bacterial development is of interest. This study investigates the efficiency of eucalyptus essential oils to inhibit the growth of Escherichia coli, Klebsiella pneumoniae, Listeria innocua, Salmonella typhimurium, Staphylococcus aureus, and Streptococcus pyogenes. Oils were extracted from eucalyptus leaves by hydrodistillation and chemically analyzed on a coupled gas chromatography-mass spectrometer. The antibacterial activity was assessed in both culture media and film models. Results indicated that eucalyptus oils were rich in different chemicals including α-pinene in oils from E. obliqua (89.3%), E. grandis (39.9%), and E. microcoris (29.6%); p-cymene in E. camaldulensis (40.1%) and E. grandis (25.8%); and eucalyptol in E. viminalis (88.3%), E. crebra (84.6%), E. polyanthemus (80.7%), E. melliodora (78%), E. maiden (74.8%), and E. globulus (70.4%) oils. Terpinen-4-ol was found in E. anceps (5.7%) and E. camaldulensis (5.6%) while oils from E. anceps contained β-phellandrene (4.7%), cis- and trans-piperitols (6.5%), (cis)-p-(2 menthen)-1-ol (8.3%), geraniol (19.9%), and piperitone (10.5%). In comparison with a known antibiotic, azithromycin, essential oils from E. grandis and E. anceps exhibited significant antimicrobial efficacy against the growth of all tested microorganisms. The antibacterial efficiency from these oils was found to be higher than other essential oils tested (p < 0.05), with minimum inhibitory concentration and minimum bactericidal concentration ranging from 0.5 to 7 and 2.5 to 20 μL/mL, respectively. Yet, at all concentrations tested (5-15 μL/mL), hydroxy-propyl cellulose (HPC) films containing these oils indicated significant inhibition efficacy of the growth of bacteria compared to HPC films (p < 0.001). Further study on E. grandis and E. anceps oils is needed for their various valorization.

Introduction: Ceftaroline is a fifth-generation cephalosporin that was recently introduced into the Egyptian market for the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections. However, limited data are available regarding the susceptibility of MRSA isolates in Egypt to this antibacterial agent. This study aimed to determine the susceptibility of MRSA strains recovered from different clinical samples to ceftaroline and to investigate the prevalence of the mecA and mecC resistance genes. Methods: A total of 412 MRSA isolates were selected from 520 Staphylococcus aureus (S. aureus) samples. Identification and antibiotic susceptibility testing were performed using the VITEK-2 compact system. Molecular identification of the nuc gene, encoding nuclease enzyme, a species-specific marker for S. aureus, and the mecA and mecC genes associated with methicillin resistance was performed using the polymerase chain reaction (PCR) technique. Moreover, the in vitro activity of ceftaroline was explored using the disc diffusion method, and its minimum inhibitory concentration (MIC) was determined according to the Clinical Laboratory Standards Institute (CLSI) criteria. Staphylococcal Protein A (spa) typing was carried out for ceftaroline nonsusceptible strains as determined by MIC. Results: Most isolates were recovered from skin and soft tissue infections. Of the 412 clinical isolates, 407 (98.7%) were susceptible to ceftaroline, with an MIC of ≤ 1 mg/L, while five isolates (1.3%) showed a susceptible dose-dependent (SDD) profile with MIC values of 2-4 μg/mL. No isolates were resistant to ceftaroline. All isolates carried the nuc gene, 94% harbored mecA, while mecC was undetected. Of the five SDD isolates, three were identified as spa type t037, corresponding to ST-239, ST-240, or ST-241 by multilocus sequence type (MLST), whereas the two remaining isolates were untypeable. Conclusions: From various clinical samples, ceftaroline demonstrated excellent in vitro activity against MRSA strains, positioning it as a promising therapeutic option for managing MRSA infections in Egypt.

The catfish is a prominent freshwater fish species farmed in Cameroon to meet the escalating demand for fish products. Despite considerable growth potential, there are concerns about the occurrence of bacteria pathogenic to both fish and humans within aquaculture systems. Research on the microbiome of catfish and their habitats remains largely unexplored. Given the critical importance of understanding the microbial composition within aquaculture systems to ensure food safety and protect public health, this study aimed to generate vital preliminary data by investigating the bacteriome of catfish gills and intestines and pond water environment in Cameroon using 16S rRNA gene amplicon sequencing. The findings revealed a diverse bacterial community (30 phyla, 678 genera, and 1056 species), with Fusobacteria, Bacteroidetes, Proteobacteria, Firmicutes, and Verrucomicrobia collectively representing over 93% of the bacterial community observed. Notably, Fusobacteria emerged as the dominant phylum in catfish gills (49.98%) and intestines (65.3%), while Proteobacteria predominated in the pond water environment (40.24%). Bacteria of genus Cetobacterium dominated all three samples (gills, 49.93%; intestines, 65.19%; and pond water, 23.85%). Furthermore, this study identified many bacterial genera, including potential fish pathogens such as Edwardsiella, Aeromonas, Plesiomonas, and Flavobacterium, and human gut bacteria such as Clostridium and Bacteroides, alongside potential beneficial probiotic bacteria such as Lactococcus spp. The coexistence of both potentially pathogenic and probiotic species underscores ecological complex dynamics within freshwater fish aquaculture and highlights the need for thorough microbial management strategies. This study provides insights into the bacterial landscape of Cameroonian aquaculture, revealing potential risks and benefits of catfish farming.

Bacteriophages (phages) have emerged as promising agents for combating bacterial pathogens, including nontyphoidal Salmonella enterica (S. enterica), the most common foodborne pathogen worldwide. The emergence of antimicrobial-resistant (AMR) S. enterica poses a severe healthcare issue. Nowadays, many countries worldwide have banned antibiotics for animal feeds or additives, and various strategies have been developed and gained popularity for their potential to address S. enterica infection. Among these strategies, phage therapy shows more promise because of its ability to specifically target bacterial pathogens without disrupting the beneficial microbiota or animal/human cells. Phages are viruses that rupture host cells through the lysis of phage-encoded endolysin proteins. Nonetheless, phages also face various challenges, including phage resistance, gene transduction, serovar diversity, and the immune response of animal/human organisms, which limit the efficacy of S. enterica. Due to this limitation of phages, endolysin, as a lytic protein for bacterial cells derived from phages, has been demonstrated as another promising solution against various bacterial pathogens, including AMR. This review is aimed at discussing the benefits and limitations of phage therapies and exploring the promising potential of phage-encoded endolysins in controlling S. enterica.

Objectives: The objective was to assess the antimicrobial effect of cinnamaldehyde and α-terpineol on mono-species and dual-species biofilms involved in endodontic infection. Materials and Methods: The phytoconstituents were used at a concentration of 10 mg/mL. The biofilms of Candida albicans (ATCC 90028) and Enterococcus faecalis (ATCC 29212) were developed for 7 days and evaluated by metabolic capacity analysis using MTT, cell viability analysis by CFU/mL, and phospholipase activity. The RPMI 1640 medium was used as the negative control and sodium hypochlorite 2.5% and chlorhexidine 2% were used as positive controls. Data were analyzed by a Kruskal-Wallis test and stepwise with adjusted Bonferroni for nonnormal data and an ANOVA one-way test followed by Tukey's post hoc test for normal data (α = 5%). Results: The cellular metabolism of the C. albicans and E. faecalis mono-species biofilms was reduced by cinnamaldehyde and α-terpineol (p < 0.05). For dual-species biofilm, only α-terpineol showed differences compared to the negative control (p < 0.05). The phytoconstituents showed an inhibitory effect on cell viability (CFU/mL) and phospholipase activity of biofilms, having an activity similar to sodium hypochlorite (p > 0.05). Conclusions: The phytoconstituents cinnamaldehyde and α-terpineol, at a concentration of 10 mg/mL, had an inhibitory effect on mono-species and dual-species biofilms of E. faecalis and C. albicans.

The eco-friendly and cost-effective biological synthesis of nanomaterials is rapidly gaining attention. This study synthesized silver nanoparticles (AgNPs) using an aqueous extract of Senna italica leaves and silver nitrate (AgNO₃). The synthesized AgNPs were characterized using UV-Vis spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD). UV-Vis spectroscopy confirmed the formation of AgNPs, displaying a characteristic surface plasmon resonance peak at 445 nm. TEM and SEM analyses revealed spherical nanoparticles with sizes ranging from 12.7 to 24 nm. FTIR spectra identified bands at 1636 and 3496 cm^-1, corresponding to C=O and O-H groups, indicating their role in stabilizing the nanoparticles. XRD analysis revealed diffraction planes at 111, 200, 220, and 311, consistent with the face-centered cubic structure of silver. The AgNPs demonstrated significant antimicrobial activity against fungi and Gram-negative and Gram-positive bacteria, with Escherichia coli showing the highest sensitivity (MIC = 0.014  μg/mL). SEM analysis of E. coli showed that untreated cells retained their normal morphology, whereas AgNP-treated cells appeared shriveled and deformed. These results underscore the potential of Senna italica-derived AgNPs as effective antimicrobial agents. Future studies will be aimed at investigating the detailed mechanisms underlying the effects of AgNPs on bacterial cell structure and growth.

Cosmetic tools, such as brushes and sponges, are integral to beauty routines but are often neglected in terms of hygiene, posing risks of bacterial contamination and related skin issues. This study investigates bacterial contamination in 57 cosmetic brushes collected from users in Jeddah, Saudi Arabia. Bacterial isolates were characterized morphologically and identified through 16S rRNA gene sequencing. The results revealed a diverse microbial profile, with Gram-positive bacteria predominating (81%), including Staphylococcus and Micrococcus species, alongside Gram-negative bacteria such as Pseudomonas spp. A survey of 370 participants highlighted inconsistent cleaning habits, with 44.3% rarely cleaning their brushes and 27.8% reporting skin problems potentially linked to contaminated tools. A statistical analysis revealed significant correlations between awareness of hygiene practices and concerns about bacterial infections (p < 0.05), yet no direct association was found between cleaning frequency and skin issues (p = 0.698). This study emphasizes the need for public education on the proper maintenance of cosmetic tools to minimize health risks and promote safer beauty practices.

Cholera is a life-threatening diarrheal disease caused by Vibrio cholerae, with recurring outbreaks in Iraq, including the Kurdistan Region. Despite its endemic nature, outbreaks have primarily been reported by the health sector without comprehensive molecular epidemiological investigations. Limited studies have characterized outbreak dynamics, prevalence, and antimicrobial resistance, hindering effective public health interventions. This study aimed to analyze the prevalence, molecular characteristics, and antibiotic resistance of V. cholerae isolates from the 2023 outbreak in Sulaymaniyah, Kurdistan, Iraq. A total of 1200 diarrheic stool samples were collected from Shar Hospital between July and October 2023. Bacterial isolation was performed using microbiological methods and automated VITEK 2 analysis, followed by serological identification (O1 and O139 antisera) and 16S rRNA gene sequencing. Antibiotic susceptibility testing (AST) was conducted to assess resistance patterns. The outbreak prevalence was 0.015%, with the highest infection rate in August (0.009%). The overall infection rate was 28.91% (347/1200), with the most affected age groups being 19-33 years (27.66%) and 34-48 years (26.22%). Infection was more common in females (55.6%) than males (44.4%). Phylogenetic analysis revealed high genetic similarity to the V. cholerae Kuwait1 strain, suggesting potential introduction from southern Iraq, possibly due to an influx of tourists. Furthermore, antibiotic susceptibility testing revealed that all V. cholerae isolates were susceptible to most tested antibiotics; however, complete resistance (100%) was observed against amikacin, amoxicillin, amoxiclav, nalidixic acid, and trimethoprim, with partial resistance (30%) to tetracycline. Cholera remains a major public health concern in Kurdistan, particularly in Sulaymaniyah, due to recurrent outbreaks. Molecular techniques provided crucial insights into outbreak tracking and genetic relatedness, while AST profiling highlighted the urgent need for revised treatment guidelines. Strengthening water sanitation, continuous antimicrobial resistance monitoring, and targeted public health interventions are essential for preventing future outbreaks.

Bacterial proteases are valuable enzymes that accelerate the hydrolysis of peptide bonds within protein molecules. This study aimed to screen, identify, and optimize bacteria-producing protease from a tannery waste disposal site. Then, 36 morphologically distinct bacterial isolates were obtained from the Dire Tannery waste disposal site in Addis Ababa, Ethiopia. Among these isolates, DT-15 demonstrated the highest protease activity, with a clear zone of 19.00 ± 0.75 mm on skim milk agar, indicating its efficacy as a protease producer. Further morphological and molecular characterization of the most promising isolate was conducted. Based on its 16S rRNA sequence, the most effective isolate was identified as Bacillus pumilus. To enhance protease production, optimization experiments were carried out, resulting in an optimal enzyme activity of 506 ± 0.037 U/mL achieved after 60 h of incubation at 37°C and pH 7, using peptone and glucose as the nitrogen and carbon sources, respectively. Thus, the isolated bacterium has the potential to be utilized for various biotechnological applications, such as leather processing, detergent formulation, and food production. Further studies could focus on its applications in industrial processes.