Higher Biofilm Formation Research Articles

Wastewater-based surveillance of Vibrio cholerae: Molecular insights on biofilm regulatory diguanylate cyclases, virulence factors and antibiotic resistance patterns

Vibrio cholerae is an inherent inhabitant of aquatic ecosystems. The Indian state of West Bengal, especially the Gangetic delta region is the highest cholera affected region and is considered as the hub of Asiatic cholera. V. cholerae were isolated from publicly accessible wastewater of Midnapore, West Bengal, India. Serotyping determined all isolates to be of non-O1/non-O139 serogroups. Moderate biofilm-forming abilities were noticed in most of the isolates (74.7 %) while, high biofilm formation was recorded for only 6.3 % isolates and 19 % of isolates exhibited low/non-biofilm-forming abilities. PCR-based screening of crucial diguanylate cyclases (DGCs) involved in cyclic-di-GMP-mediated biofilm signaling was performed. cdgH and cdgM were the most abundant DGCs among 93.7 % and 91.5 % of isolates, respectively. Other important DGCs, i.e., cdgK, cdgA, cdgL, and vpvC were present in 84 %, 75.5 %, 72 % and 68 % of isolates, respectively. Besides, the non-O1/non-O139 isolates were screened for the occurrence of virulence factor encoding genes. Moreover, among these non-O1/non-O139 isolates, two strains (3.17 %) harbored both ctxA and ctxB genes, which encode the cholera toxin associated with epidemic cholera. ompU was the most prevalent virulence factor, present in 24.8 % of isolates. Other virulence factors like, zot and st were found in 4.7 % and 9.5 % of isolates. Genes encoding tcp and ace were found to be PCR-negative for the isolates. Additionally, crucial virulence factor regulators, toxT, toxR and hapR were found to be PCR-positive in all the isolates. Antibiotic resistance patterns displayed further vulnerabilities with decreased sensitivity towards commonly used antibiotics with multiple antibiotic resistance index ranging between 0.37 and 0.62. The presence of cholera toxin-encoding multi-drug resistant (MDR) V. cholerae strains in environmental settings is alarming. High occurrence of DGCs are considered to encourage further investigations to use them as alternative therapeutic targets against MDR cholera pathogen due to their unique presence in bacterial systems.

Hypervirulent Carbapenem-Susceptible Klebsiella pneumoniae ST412/K57 with Strong Biofilm Formation: association with gas gangrene and sepsis.

Hypervirulent Klebsiella pneumoniae (hvKp) poses a serious public health threat. Gas gangrene caused by hvKp was rarely reported, potentially resulting in a poor prognosis. In this study, we described the case of a hospitalized patient with gas gangrene and sepsis by hvKP. The carbapenem-susceptible hypervirulent Klebsiella pneumoniae (CS-hvKp) strains KPLSN and KPLSX were isolated from the knee joint pus and blood specimens of the patient for further investigations. Whole genome sequencing revealed that KPLSN and KPLSX were highly homologous (SNPs<10) and belonging to ST412/K57. The minimum inhibitory concentration and minimum bactericidal concentration under biofilm values of meropenem in KPLSN and KPLSX were significantly higher than planktonic state (>128 mg/L versus 0.25 mg/L, P<0.0001). These two strains had high biofilm formation ability, and fluorescence staining experiments results showed that they were not easily killed by meropenem in the biofilm state. KPLSN and KPLSX showed high capsular production and were confirmed with high virulence through experiments with the Galleria mellonella and BALB/c mice abdominal infection model. The persistent symptoms may be due to enhanced biofilm and capsule formation. Global ST412 strains phylogenetic analysis showed their evolution towards higher virulence and resistance. It emphasizes the critical need for judicious antibiotic use and novel therapeutic approaches to combat special infections caused by these pathogens.

Biofilm Formation among Staphylococcus aureus Strains from Food Contact Surfaces in Households: A Public Health Concern

Staphylococcus aureus is a foodborne pathogen of serious public health concern due to its high biofilm formation capability. One of the contributing factors to foodborne illnesses is improper cleaning and sanitization of food contact surfaces This study aimed to determine the prevalence of S. aureus with biofilm formation potential (BFP) from various food contact surfaces. A total of 100 samples were obtained, 20 from each of stainless steel spoons, plastic plates, plastic eating bowls, plastic cutting boards and glass cups. Samples were obtained by surface swabbing. The cotton swabs were streaked onto nutrient agar plates and incubated overnight. Colonies obtained were subjected to Gram staining, coagulase, catalase and DNAse tests for the identification of S. aureus. The identified S. aureus strains were subjected to biofilm formation potential assay using crystal violet assay (CV-assay) in polystyrene 96-well microtitre plates. Out of the 100 samples obtained, 26 were found to harbour S. aureus. Moreover, out of the 20 isolates, 2 (10%) were from stainless steel spoons, 8 (40%) from plastic plates, 5 (25%) from plastic-eating bowls, 10 (50%) from plastic cutting boards and 1 (5%) from glass cups. Additionally, 11 (42%) of the strains had strong BFP, 11 (42%) had moderate BFP, 3 (12%) and 1 (4%) had no BFP. Presence of S. aureus with BFP on food contact surfaces should be checked to avoid foodborne outbreaks due to this organism.

Characteristics of Candida albicans Derived From HIV-Positive Individuals With Oral Candidiasis: Genotyping, Phenotypic Variation, Antifungal Susceptibility, and Biofilm Formation.

Oral candidiasis (OC) is one of the most common mucosal infections in those afflicted with HIV/AIDS. This study aimed to provide detailed information on the phenotype, genotype, antifungal susceptibility, and biofilm formation ability of oral Candida albicans isolated from HIV-infected patients with OC. A total of 25 C. albicans isolates were collected from oral lesions of HIV-infected patients referred to Behavioral Diseases Counseling Center affiliated with Ahvaz Jundishapur University of Medical Sciences, Iran. The antifungal susceptibility testing was done according to CLSI M27 guideline (fourth edition). The crystal violet method was used to evaluate the biofilm formation ability of isolates. Different phenotypes were identified on yeast extract-peptone-dextrose agar medium supplemented with phloxine B. Genotyping analysis of the isolates was performed using high-resolution melting (HRM) assays and ABC genotyping. The highest and lowest susceptibility of the C. albicans isolates was found for fluconazole 24 (96%) and ITC 18 (72%), respectively. Forty-eight percent of the isolates had high biofilm formation ability and exhibited gray cell type. The most common genotype was genotype B (52%). HRM analysis of HIS3, EF3, and CDC3 markers showed three, four, and five different groups, respectively. Investigating the phenotype, antifungal susceptibility and biofilm formation ability of the C. albicans isolates obtained from oral lesions of HIV-infected patients revealed that the dominant genotypes in the current research could cause more serious infections from the oral source. We recommend further research with a larger sample size to determine the molecular epidemiology of C. albicans among HIV patients in Iran.

The effect of epigallocatechin gallate on Streptococcus Gordonii biofilm formation

Background: Dental caries, as a primary disease in dentistry, is strongly influenced by the presence of biofilms. One of the Gram-positive bacteria that acts as an initiator in the biofilm formation process is Streptococcus gordonii. As the primary catechin in green tea, epigallocatechin gallate (EGCG) is easily found in our daily lives, and it has a broad spectrum of antimicrobial effects. Several studies have revealed that EGCG inhibited the growth of Gram-positive bacteria, including inhibiting biofilm formation by damaging the bacterial cell wall and reducing glucosyltransferase activity. However, there is still limited information that explains the effect of EGCG on S. gordonii bacterial biofilms. Purpose: This study aims to analyze the effect of EGCG in inhibiting the formation of S. gordonii bacterial biofilms. Methods: This study was an in-vitro experimental laboratory study, with samples divided into five groups, namely, the group containing BHIB-bacteria, the BHIB-bacteria-5% sucrose groups, and the treatment groups containing BHIB-bacteria-5% sucrose-EGCG with concentrations of 12.5%, 6.25%, and 3.125%, respectively, incubated for 24 hours. The data was analyzed using the Kruskal–Wallis test. Results: There was a significant difference in the formation of biofilms in S. gordonii bacteria with the addition of 5% sucrose in BHIB compared with the group of S. gordonii bacteria in BHIB. The highest biofilm formation in the group containing bacteria-BHIB-5% sucrose, while the lowest biofilm formation occurred in the treatment group containing bacteria-BHIB-5% sucrose-12.5% EGCG with significant difference between the group. Conclusion: The addition of EGCG 12.5% inhibits the formation of S. gordonii biofilms.

In vitro determination of antifungal susceptibility and virulence factors in Candida species causing candidemia in North India Region

Candidiasis is the most incessant fungal disease affecting human population worldwide. In this research work, we explored the characteristics contributing to pathogenicity of Candida infections, from serious bloodstream conditions like candidemia. Candida spp. were isolated from the blood of 120 suspected patients and assessed their susceptibility to antifungal treatments via MIC measurements. Enzyme activities (phospholipase, proteinase, hemolysin, and esterase) were examined alongside biofilm formation, with surface analysis conducted via SEM. Statistical analysis, facilitated by GraphPad Prism 8.4.2, identified correlations among data points. Results reveal that non-albicans spp. like Candida auris heightened resistance to antifungal treatments compared to Candida albicans. Candida tropicalis exhibited no phospholipase activity but shows activity to proteinase and esterase. Conversely, C. albicans show a case of elevated hemolysin activity. Non-albicans Candida i.e. C. tropicalis and Candida krusei were isolated as high biofilm formers in comparison to C. albicans. Statistical analysis yielded a highly significant p-value (< 0.001), affirming the robustness of our results. In conclusion, non-albicans species exhibit a broader spectrum of resistance mechanisms compared to C. albicans in pathogenicity. This investigation sheds light on diverse virulence strategies employed by different Candida species, informing future treatment approaches.

Establishment of the improved colonization of Escherichia coli laboratory strain in the intestine mediated by single gene deletion

In light of the emerging importance of the gut microbiome in human health, there is a need to improve the colonization efficiency of therapeutic bacteria called probiotics. Despite their recognized potential, artificially administered bacteria exhibit poor colonization in the intestine, limiting their therapeutic efficacy. Addressing this challenge requires innovative strategies; however, reported examples are limited. In nature, including in the intestinal tract, bacteria live via biofilm formation. Recently, it has been reported that RNase I, a member of the RNase T2 family conserved among almost all species, including bacteria, inhibits biofilm formation in Escherichia coli. In this study, we focus on these results and investigate the relationship between high biofilm formation and intestinal attachment using a non-settling E. coli laboratory strain as a probiotic model. The intestinal colonization abilities were evaluated through a microfluidic device mimicking the intestinal tract and through oral administration to mice. The in vitro and in vivo experiments showed that the E. coli strain lacking RNase I exhibited remarkable stability in intestinal colonization. We investigated the observation of colonization using fluorescence in situ hybridization, and inoculated E. coli cells were aggregated with the gut microbiome in the cecum and colon. This study proposes a technique to improve the intestinal colonization of bacteria by simply manipulating a single gene disruption, and it is expected to contribute to future research on the colonization of useful bacteria.

Probiotic Potential and Application of Indigenous Non-Starter Lactic Acid Bacteria in Ripened Short-Aged Cheese.

There are massive sources of lactic acid bacteria (LAB) in traditional dairy products. Some of these indigenous strains could be novel probiotics with applications in human health and supply the growing needs of the probiotic industry. In this work, were analyzed the probiotic and technological properties of three Lactobacilli strains isolated from traditional Brazilian cheeses. In vitro tests showed that the three strains are safe and have probiotic features. They presented antimicrobial activity against pathogenic bacteria, auto-aggregation values around 60%, high biofilm formation properties, and a survivor of more than 65% to simulated acid conditions and more than 100% to bile salts. The three strains were used as adjunct cultures separately in a pilot-scale production of Prato cheese. After 45days of ripening, the lactobacilli counts in the cheeses were close to 8 Log CFU/g, and was observed a reduction in the lactococci counts (around -3 Log CFU/g) in a strain-dependent manner. Cheese primary and secondary proteolysis were unaffected by the probiotic candidates during the ripening, and the strains showed no lipolytic effect, as no changes in the fatty acid profile of cheeses were observed. Thus, our findings suggest that the three strains evaluated have probiotic properties and have potential as adjunct non-starter lactic acid bacteria (NSLAB) to improve the quality and functionality of short-aged cheeses.

Phenotypic and genotypic characterization of Staphylococcus aureus strains isolated from otitis externa: Emergence of CC30-spa t019-SCCmec IV carrying PVL as major genotype

The increasing emergence of Staphylococcus aureus as the primary causative agent of otitis externa has been noted; however, detailed information regarding the molecular characteristics of these strains in Iran remains scarce. The current study aims to investigate both genotypic and phenotypic attributes of S. aureus strains implicated in ear infections. In the present work, we analyzed 60 S. aureus strains isolated from cases of otitis externa over a period of 45 months. The resistance patterns were determined using disk diffusion and microbroth dilution methods. All S. aureus isolates were confirmed by the nucA polymerase chain reaction assay, and their biofilm production was assessed by a microtiter plate assay. Molecular characterization of the isolates was performed using the staphylococcal cassette chromosome mec, multilocus sequence typing, and staphylococcus protein A typing methods. Overall, the results indicated that 44 out of 60 S. aureus isolates (73.3 %) were methicillin-resistant Staphylococcus aureus. Resistance to mupirocin and vancomycin was observed in 13.3 % and 1.7 % of the tested isolates, respectively. Furthermore, out of the 60 S. aureus isolates, 56 strains (93.4 %) were classified as positive biofilm strains at different levels. Twelve distinct clonal lineages were identified. The vast majority of S. aureus isolates belonged to CC30/ST30-MRSA IV/t019 (41.7 %). Among the 31 strong biofilm producers, the majority (64.5 %) belonged to CC30/ST30-MRSA IV/t019 clone. Biofilm negative isolates belonged to CC22/ST22 (2 isolates), CC8/ST585 (one isolate), and CC8/ST8 (one isolate). Our result revealed that about three-quarters of PVL-positive strains belonged to CC30/ST30. Our data confirmed the presence of MSSA strains among CC30/ST30 and CC22/ST22 isolates. The mupirocin resistant isolates (n = 8) belonged to CC8/ST585-MRSA III/t713 (37.5 %), CC8/ST239-MRSA III/t030 (25 %), CC8/ST8-MRSA IV/t008 (12.5 %), CC8/ST239-MRSA III/t037 (12.5 %), and CC22/ST22-MRSA IV/t790 (12.5 %) lineages. The VRSA strain belonged to the CC8/ST8-MRSA IV/t008 lineage, carrying the vanA determinant. iMLSB phenotypes (n = 14) were distributed across different lineages, including CC30/ST30-MRSA IV/t019 (21.5 %), CC30/ST30-MSSA/t021 (21.5 %), CC22/ST22-MSSA/t005 (14.3 %), CC8/ST239-MRSA III/t030 (14.3 %), CC22/ST22-MSSA/t1869 (7.1 %), CC22/ST22-MRSA IV/t790 (7.1 %), CC8/ST239-MRSA III/t037 (7.1 %), and CC1/ST772-MRSA IV/t10795 (7.1 %). These findings highlight significant genotypic diversity and high biofilm formation among our isolates. The frequent occurrence of the CC/ST30 clone in S. aureus strains isolated from otitis externa reflects the emergence of these lineages as a predominant clone in Iran, posing a significant public health concern.

Composting manure in the poultry farm harbours multidrug-resistance Salmonella

ABSTRACT Salmonella is one of the leading foodborne pathogens that cause gastroenteritis. It is imperative to monitor Salmonella contamination within poultry farms. This study focuses on the prevalence of Salmonella in composting manure at poultry farms a potential and persistent contamination sources. A batch of manure samples (n = 10) were collected from a local poultry farm, and half of the manure samples were detected to be Salmonella-positive. Serotyping results showed four serotypes among different isolated strains, including Typhimurium, Typhi, Newport, and Dublin. Isolates from manure generally demonstrated a high ciprofloxacin resistance and biofilm formation capacity. Multi-drug resistance was found in isolates from organic manure that had been fermented using high-temperature aerobic technology. Our study indicated that composting manure harboured Salmonella and might facilitate the transmission of Salmonella and the development of antimicrobial resistance. Proper composting strategies are needed to reduce the transmission of antimicrobial resistance and Salmonella.

Biofilm formation and antibiotic resistance in patients with urolithiasis: assessment of phenotypic and genotypic

Aim: Urolithiasis is a common public health problem that significantly impacts the community. The objective of this study was to identify the prevalent pathogens responsible for urinary tract infections in patients with urolithiasis and investigate the biofilm forming ability of these strains phenotypically and molecularly. Materials and Methods: A total of 100 patients who presented to Kirkuk Training and Research Hospital with symptoms of urinary tract infection and were diagnosed with kidney stones were included in our study conducted between May 2021 and November 2022. Clinically significant bacteria from urine samples were identified using routine conventional methods. Biofilm formation of the identified strains was examined by microplate method. Results: The most frequently isolated agents were Escherichia coli (n:36) and Proteus mirabilis (n:17). Biofilm formation was detected in 89% of E. coli strains and 94% of P. mirabilis strains. Conclusion: The results obtained are important in terms of high biofilm formation, especially in E. coli and P. mirabilis strains, and the frequent presence of genes related to this biofilm formation.

Emerging threats of high biofilm formation and antibiotic resistance in clinical methicillin-resistant Staphylococcus aureus (MRSA) isolates from Pakistan

ObjectivesThis multicenter study, conducted from a One Health perspective, aimed to comprehensively examine the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) infections and their biofilm-forming capabilities in Pakistan. Phylogenetic analysis of the study isolates was also performed. MethodsA total of 150 MRSA isolates were screened from various clinical samples using Cefoxitin antibiotic discs. Genotypic confirmation was conducted through mecA, S. aureus-specific nuc, and 16S rRNA genes. Biofilm formation was assessed using Congo red agar (CRA) and slime layer quantification methods. The intercellular adhesion (ica) operon genes, specifically icaA and icaD, were detected. Phylogenetic analysis utilized the 16S rRNA sequences. Statistical associations between various parameters were determined using chi-square analysis. ResultsThe presence of the mecA gene was observed in 131 out of 150 isolates (87.3%). CRA identified 28% and 40% of isolates as strong and moderate biofilm producers, respectively, while 9.3% were classified as non-biofilm producers. The slime layer assay exhibited higher sensitivity, classifying only 4.7% of isolates as non-biofilm producers. Biofilm-forming genes icaA and icaD were detected in 85.3% and 86.7% of the isolates, respectively. Antibiotic resistance was more prevalent among biofilm-forming isolates, particularly against ciprofloxacin, levofloxacin, erythromycin, trimethoprim-sulfamethoxazole, and fosfomycin. Ceftaroline demonstrated efficacy irrespective of biofilm-forming abilities. Conversely, non-biofilm producers exhibited complete susceptibility to clarithromycin and tigecycline. ConclusionsClinical MRSA strains exhibit a substantial potential for biofilm formation, contributing to a resistant phenotype. Routine antibiotic testing in clinical settings that overlook the biofilm aspect may lead to the failure of empiric antibiotic therapy.

Molecular characterization of the multi-drug resistant Myroides odoratimimus isolates: a whole genome sequence-based study to confirm carbapenem resistance.

The bacteria belonging to the Myroides genus are opportunistic pathogens causing community or hospital-acquired infections that result in treatment failure due to antibiotic resistance. This study aimed to investigate molecular mechanisms of antibiotic resistance, clonal relatedness, and the biofilm forming capacity of the 51 multi-drug resistant Myroides odoratimimus. All isolates were screened for blaKPC, blaOXA, blaVIM, blaIMP, blaMUS, blaTUS, blaNDM, and blaB genes by using PCR amplification. Whole genome sequencing (WGS) was applied on three randomly selected isolates for further investigation of antibiotic resistance mechanisms. Clonal relatedness was analyzed by Pulsed-field gel electrophoresis (PFGE) and the microtiter plate method was used to demonstrate biofilm formation. All isolates were positive for biofilm formation. PCR analysis resulted in a positive for only the blaMUS-1 gene. WGS identified blaMUS-1, erm(F), ere(D), tet(X), and sul2 genes in all strains tested. Moreover, the genomic analyses of three strains revealed that genomes contained a large number of virulence factors (VFs). PFGE yielded a clustering rate of 96%. High clonal relatedness, biofilm formation, and multi-drug resistance properties may lead to the predominance of these opportunistic pathogens in hospital environments and make them cause nosocomial infections.

Delving into the lifestyle of Sundarban Wetland resident, biofilm producing, halotolerant Salinicoccus roseus: a comparative genomics-based intervention

BackgroundMicrobial community played an essential role in ecosystem processes, be it mangrove wetland or other intertidal ecologies. Several enzymatic activities like hydrolases are effective ecological indicators of soil microbial function. So far, little is known on halophilic bacterial contribution and function on a genomic viewpoint of Indian Sundarban Wetland. Considering the above mentioned issues, the aims of this study was to understand the life style, metabolic functionalities and genomic features of the isolated bacterium, Salinicoccus roseus strain RF1H. A comparative genome-based study of S. roseus has not been reported yet. Henceforth, we have considered the inclusion of the intra-species genome comparison of S. roseus to gain insight into the high degree of variation in the genome of strain RF1H among others.ResultsSalinicoccus roseus strain RF1H is a pink-red pigmented, Gram-positive and non-motile cocci. The bacterium exhibited high salt tolerance (up to 15% NaCl), antibiotic resistance, biofilm formation and secretion of extracellular hydrolytic enzymes. The circular genome was approximately 2.62978 Mb in size, encoding 574 predicted genes with GC content 49.5%. Presence of genomic elements (prophages, transposable elements, CRISPR-Cas system) represented bacterial virulence and multidrug-resistance. Furthermore, genes associated with salt tolerance, temperature adaptation and DNA repair system were distributed in 17 genomic islands. Genes related to hydrocarbon degradation manifested metabolic capability of the bacterium for potential biotechnological applications. A comparative pangenome analysis revealed two-component response regulator, modified C4-dicarboxylate transport system and osmotic stress regulated ATP-binding proteins. Presence of genes encoding arginine decarboxylase (ADC) enzyme being involved in biofilm formation was reported from the genome. In silico study revealed the protein is thermostable and made up with ~ 415 amino acids, and hydrophilic in nature. Three motifs appeared to be evolutionary conserved in all Salinicoccus sequences.ConclusionThe first report of whole genome analysis of Salinicoccus roseus strain RF1H provided information of metabolic functionalities, biofilm formation, resistance mechanism and adaptation strategies to thrive in climate-change induced vulnerable spot like Sundarban. Comparative genome analysis highlighted the unique genome content that contributed the strain’s adaptability. The biomolecules produced during metabolism are important sources of compounds with potential beneficial applications in pharmaceuticals.

Role of Bacillus cereus biofilm formation behavior in virulence and pathogenic characteristics

AbstractThis study aimed to examine the potential link between Bacillus cereus biofilm formation, virulence, and pathogenicity. The biofilm formation abilities of nine B. cereus strains isolated from food and two reference strains (ATCC 10876 and ATCC 25621) were measured using a crystal violet assay. Among the tested strains, three strains (GIHE 617‐5, GIHE 86‐09, and GIHE 728‐17) and both reference strains were capable of biofilm formation. A positive correlation was obtained for higher cell surface hydrophobicity and increased biofilm formation. In contrast, HPLC analysis for elevated autoinducer‐2 (Al‐2) production revealed a negative impact on biofilm formation. PCR data indicated that all tested strains were capable of producing common B. cereus enterotoxins, including Hbl—A, C, and D, CytK, Nhe—B and C, EntFM, and BceT, but were negative for production of the emetic toxin cereulide and the pore‐forming toxin Hly II. Meanwhile, RT‐PCR data revealed a close correlation between high biofilm formation and the upregulation of several tested virulence genes for selected strains. However, elevated upregulation of virulence genes was not consistent in all of the higher biofilm‐forming strains. Cytotoxicity analysis revealed higher virulence characteristics compared to those of low biofilm‐forming strains.

Presence of methicillin-resistant Staphylococcus aureus in raw cow’s milk: adhesive capacities and extracellular enzymes characterization

Raw milk contamination by Methicillin-resistant S. aureus (MRSA) threatens food safety and leads to public health problems. Our study evaluates biofilm formation and virulence factors among 21 MRSA in raw cow’s milk. Methicillin resistance was confirmed by cefoxitin screening using the automated VITEK2 system, with a minimum inhibitory concentration greater than 8 mg/l. Qualitative characterization of biofilm-producing strains was performed on Congo red agar (CRA), with a semi-quantitative adhesion test on 96-well tissue culture plates (TCP). The ability to produce different enzymes was evaluated, such as caseinase, lipase, and phospholipase (lecithinase). The surface hydrophobicity of the bacteria was determined, and the autoaggregation test was used to predict the interactions between bacterial cells. Among the tested strains, 61.9% were biofilm producers in the CRA, developing a positive and variable phenotype. Furthermore, 19.05% and 80.95% of isolates were high and low biofilm formation on TCP. The enzymatic activity showed that lécithinase, caseinase, and lipase activities were detected in 100%, 80.95%, and 80.95% of cases. Highly hydrophilic (85.71%) and weakly hydrophobic (14.29%) were detected in MRSA isolates. The strains showed that 71.43% were moderate autoaggregation and 28.57% were low autoaggregation. No significant difference was found between the CRA method and TCP (P&gt; 0.05). A significant association was found between adhesion capacity and bacterial autoaggregation in S. aureus strains (p&gt;0.05). On the other hand, no statistical association between the hydrophobicity of microbial strains and adhesion capacity (p&lt;0.05) was found. The same result was for the hydrophobicity of microbial strains and autoaggregation (p&lt;0.05). This investigation could be beneficial for developing new control measures, prevention, and effective treatment against staphylococcal bacterial resistance.

The ability of two indigenous bacteria isolated from Moroccan olive tree to promote the growth of olive seedlings in the presence of the pathogen Verticillium dahliae

ABSTRACT The rhizosphere of olive trees (Olea europaea L.) is a source of bacteria with a high potential for biocontrol and plant growth promotion. In the present study, two native olive tree gram-negative bacteria were isolated from the rhizosphere of century-old trees in the region of Zouala (south-eastern Morocco), known for its arid climate and saline soils. The strains Pantoea agglomerans and Enterobacter ludwigii exhibited high tolerance to high PEG and NaCl concentrations, and significant plant growth-promoting (PGP) potential in vitro. The two strains efficiently solubilised phosphate in its two forms (TCP and RP), and Mica as a source of potassium and produced IAA. The two strains exhibited in vitro inhibition ability against Verticillium dahliae with partial inhibition of the growth of the mycelium by the strain P. agglomerans MRC_ZO_17. Greenhouse experiments showed that olive tree seedlings treated with the E. ludwigii MRC_ZO_97 strain significantly improved growth (dry weight) in the presence and absence of the pathogen compared to untreated plants, while the P. agglomerans MRC_ZO_17 strain showed significant effects on seedling growth only in the presence of the pathogen V. dahliae OV1 defoliating pathotype. Both strains showed high exopolysaccharides (EPS) production and good biofilm formation, making them excellent plant growth-promoting rhizobacteria (PGPRs) and Biological Control Agents (BCAs) with great potential to survive in soil under stress conditions.

Photodynamic Therapy and Its Synergism with Melittin Against Drug-Resistant Acinetobacter baumannii Isolates with High Biofilm Formation Ability.

Drug-resistant biofilm producer A. baumannii isolates are a global concern that warns researchers about the development of new treatments. This study was designed to analyze the effect of photodynamic therapy (PDT) as monotherapy and associated with melittin on multidrug-resistant A. baumannii isolates. Sub-lethal doses of photosensitizer, LED, and PDT were determined. The PDT effect on the biofilm and expression of biofilm-associated genes was evaluated by scanning electron microscopy and quantitative real-time PCR (qRT-PCR) methods, respectively. The synergistic effect of PDT and melittin on the survival of MDR/XDR strong biofilm producer isolates was evaluated by checkerboard assay. Survival rates were significantly decreased at the lowest concentration of 12.5-50μg/ml in 4min at an energy density of 93.75J/cm2 (P < 0.05). The optimized PDT method had a bactericidal effect against all tested groups, and the mean expression levels of csu, abaI, bap, and ompA genes in the strong biofilm producers were decreased significantly compared to the control group. The combined effect of LED and melittin successfully reduced the MDR/XDR A. baumannii strong biofilm producers' growth from 3.1 logs. MB-mediated aPDT and combined treatment of PDT with melittin, which has been investigated for the first time in this study, can be an efficient strategy against MDR/XDR A. baumannii isolates with strong biofilm production capacity.

Influence Of Surface Treatment On The Physical Properties And Biofilm Formation Of Zirconia-Reinforced Lithium Silicate Ceramics: In Vitro Trial.

To evaluate the performance of fully (Celtra Duo, Dentsply Sirona) and partially (VITA Suprinity, VITA) crystallized zirconia-reinforced lithium silicate and partially sintered lithium disilicate (IPS e.max CAD, Ivoclar Vivadent) glass-ceramics submitted to polishing, glazing, or no surface treatment after aging. Specimens of each glass-ceramic were subjected to polishing with rubber cups (POL), glazing (GL), or control (C; no treatment) and afterwards aged with 18,000 thermal cycles (5°C to 55°C). The average roughness (Ra), 2D and 3D morphology, contact angle, multispecies biofilm formation (Streptococcus mutans and Candida albicans), and mechanical strength were evaluated by atomic force microscopy (AFM, n = 5), sessile-drop goniometry (n = 5), spectrophotometry (n = 5), and flexural strength test (n = 10), respectively. Data were analyzed using two-way analysis of variance and Tukey test (α = 5%). POL promoted lower Ra than glazing, and Celtra Duo presented higher Ra than IPS e.max CAD (P < .05). Surfaces without polishing promoted higher Ra than the POL group (P < .001), greater contact angle (P < .001), and significant morphologic changes, regardless of the glass-ceramic. Irrespective of the treatment, the contact angle was higher in Celtra Duo, and regardless of the material, there was higher biofilm formation and lower flexural strength of unpolished compared to POL or GL ceramics. Polishing with rubber cups promoted lower roughness and minor morphologic surface alterations, but biofilm formation and flexural strength were similar to the glazed surface. In general, Celtra Duo and VITA Suprinity showed similar behavior to IPS e.max CAD, which makes zirconia-reinforced lithium silicate glass-ceramics a good option for indirect restorations.

Aqueous spice extracts as alternative antimycotics to control highly drug resistant extensive biofilm forming clinical isolates of Candida albicans.

Candida albicans form biofilm by associating with biotic and abiotic surfaces. Biofilm formation by C. albicans is relevant and significant as the organisms residing within, gain resistance to conventional antimycotics and are therefore difficult to treat. This study targeted the potential of spice-based antimycotics to control C. albicans biofilms. Ten clinical isolates of C. albicans along with a standard culture MTCC-3017 (ATCC-90028) were screened for their biofilm-forming ability. C. albicans M-207 and C. albicans S-470 were identified as high biofilm formers by point inoculation on Trypticase Soy Agar (TSA) medium as they formed a lawn within 16 h and exhibited resistance to fluconazole and caspofungin at 25 mcg and 8 mcg respectively. Aqueous and organic spice extracts were screened for their antimycotic activity against C. albicans M-207 and S-470 by agar and disc diffusion and a Zone of Inhibition was observed. Minimal Inhibitory Concentration was determined based on growth absorbance and cell viability measurements. The whole aqueous extract of garlic inhibited biofilms of C. albicans M-207, whereas whole aqueous extracts of garlic, clove, and Indian gooseberry were effective in controlling C. albicans S-470 biofilm within 12 h of incubation. The presence of allicin, ellagic acid, and gallic acid as dominant compounds in the aqueous extracts of garlic, clove, and Indian gooseberry respectively was determined by High-Performance Thin Layer Chromatography and Liquid Chromatography-Mass Spectrometry. The morphology of C. albicans biofilm at different growth periods was also determined through bright field microscopy, phase contrast microscopy, and fluorescence microscopy. The results of this study indicated that the alternate approach in controlling high biofilm-forming, multi-drug resistant clinical isolates of C. albicans M-207 and S-470 using whole aqueous extracts of garlic, clove, and Indian gooseberry is a safe, potential, and cost-effective one that can benefit the health care needs with additional effective therapeutics to treat biofilm infections.