Antimicrobial and antivirulence saponins of Mimusops laurifolia leaves.

Mimusops laurifolia is a native species restricted to the Red Sea mountains and Gulf of Aden. Its leaves contain saponins with wide range of biological activities. The presented research aimed to prepare saponins-rich extract from n-butanol fraction of M. laurifolia leaves and screen it for promising antimicrobial activities. Minimum inhibitory concentration (MIC) of the prepared saponins against Candida albicans, and their potential anti-pathogenic and antivirulence effects were determined. Different concentrations of the saponins-rich extract were investigated for their antimicrobial potential, particularly against C. albicans, using the agar well diffusion method. To assess the potential antivirulence and antipathogenic effects, we carried out molecular docking of the bioactive saponins against four key enzymes in C. albicans, which are involved in virulence and/or pathogenicity. Different concentrations of the investigated mixture showed notable antifungal activity against C. albicans with an MIC value of 6.4 µg ml-1. Docking analysis of the investigated saponins showed their affinity toward the docked enzymes, particularly saponin 1 with secreted aspartic proteinase 3 and saponin 6 with secreted aspartic proteinase 5. Thereafter, the stability of these two protein-ligand interactions was investigated using molecular dynamics (MD) simulation. The molecular interactions between saponins and the enzymes' active sites were analyzed and discussed.

Engineering a Lysin with Intrinsic Antibacterial Activity (LysMK34) by Cecropin A Fusion Enhances Its Antibacterial Properties against Acinetobacter baumannii.

Bacteriophage-encoded lysins are increasingly reported as alternatives to combat Acinetobacter baumannii infections, for which limited therapeutic options are available. Some lysins, such as LysMK34, have a C-terminal amphipathic helix allowing them to penetrate the otherwise-impermeable outer membrane barrier. Another approach to kill Gram-negative pathogens with lysins relies on fusion of a peptide with outer membrane-permeabilizing properties to the lysin. In this work, we aimed to leverage the intrinsic antibacterial activity of LysMK34 by fusing the peptide cecropin A to its N terminus via a linker of three Ala-Gly repeats, resulting in engineered LysMK34 (eLysMK34). The engineered lysin has an improved antibacterial activity compared to that of the parental lysin, LysMK34, in terms of MICs (0.45 to 1.2 µM), killing rate, and killing extent. eLysMK34 has a ≥2-fold-increased activity against stationary-phase cells, and the bactericidal effect becomes less dependent on the intracellular osmotic pressure. In particular, colistin-resistant strains become highly susceptible to eLysMK34, and enhanced antibacterial activity is observed in complement-deactivated human serum. These observations demonstrate that fusion of a lysin with intrinsic antibacterial activity with a selected outer membrane-permeabilizing peptide is a useful strategy to further improve the in vitro antibacterial properties of such lysins. IMPORTANCE Phage lysins are a new class of enzyme-based antibiotics that increasingly gain interest. Lysins kill cells through rapid degradation of the peptidoglycan layer, resulting in sudden osmotic lysis. Whereas Gram-positive bacteria are readily susceptible to the actions of lysins, Gram-negative bacteria are naturally resistant, as the outer membrane protects their peptidoglycan layer. This work reveals that fusing an outer membrane-permeabilizing peptide to a lysin with intrinsic antibacterial activity results in a superior lysin that shows improved robustness in its antibacterial activity, including against the most worrisome colistin-resistant A. baumannii strains.

Distribution of integrons and phylogenetic groups among Escherichia coli causing community-acquired urinary tract infection in Upper Egypt.

Escherichia coli is a major cause of community-acquired urinary tract infections (CA-UTIs). In this study, we investigated the antimicrobial resistance patterns, the distribution of phylogenetic groups, and the prevalence and characteristics of integron-bearing E. coli isolates from outpatients with CA-UTIs in El-Minia governorate, in Upper Egypt. Out of the 583 urine samples collected, 134 were positive for E. coli, from which the most resistant isolates (n = 80) were selected for further analysis. The majority of these isolates (62.5%, 50/80) showed multidrug resistance profiles. Group B2 was the most predominant phylogenetic group (52.5%), followed by group F (21.25%), Clades I or II (12.5%), and finally isolates of unknown phylogroup (13.75%). Of the 80 isolates, 7 (8.75%) carried class 1 integrons, which contained 3 different types of integrated gene cassettes, including those conferring resistance to streptomycin/spectinomycin, trimethoprim, and some open reading frames of unknown function (gcuF). In conclusion, the types and combinations of the gene cassettes in our study may reflect the specific selective pressures to which the isolates were subjected within the study region, therefore, providing valuable data for future intervention strategies that are precisely tailored to prevent the dissemination of the uropathogenic E. coli strains circulating within Upper Egypt.

Lysin LysMK34 of Acinetobacter baumannii Bacteriophage PMK34 Has a Turgor Pressure-Dependent Intrinsic Antibacterial Activity and Reverts Colistin Resistance.

The prevalence of extensively and pandrug-resistant strains of Acinetobacter baumannii leaves little or no therapeutic options for treatment for this bacterial pathogen. Bacteriophages and their lysins represent attractive alternative antibacterial strategies in this regard. We used the extensively drug-resistant A. baumannii strain MK34 to isolate the bacteriophage PMK34 (vB_AbaP_PMK34). This phage shows fast adsorption and lacks virulence genes; nonetheless, its narrow host spectrum based on capsule recognition limits broad application. PMK34 is a Fri1virus member of the Autographiviridae and has a 41.8-kb genome (50 open reading frames), encoding an endolysin (LysMK34) with potent muralytic activity (1,499.9 ± 131 U/µM), a typical mesophilic thermal stability up to 55°C, and a broad pH activity range (4 to 10). LysMK34 has an intrinsic antibacterial activity up to 4.8 and 2.4 log units for A. baumannii and Pseudomonas aeruginosa strains, respectively, but only when a high turgor pressure is present. The addition of 0.5 mM EDTA or application of an osmotic shock after treatment can compensate for the lack of a high turgor pressure. The combination of LysMK34 and colistin results in up to 32-fold reduction of the MIC of colistin, and colistin-resistant strains are resensitized in both Mueller-Hinton broth and 50% human serum. As such, LysMK34 may be used to safeguard the applicability of colistin as a last-resort antibiotic.IMPORTANCEA. baumannii is one of the most challenging pathogens for which development of new and effective antimicrobials is urgently needed. Colistin is a last-resort antibiotic, and even colistin-resistant A. baumannii strains exist. Here, we present a lysin that sensitizes A. baumannii for colistin and can revert colistin resistance to colistin susceptibility. The lysin also shows a strong, turgor pressure-dependent intrinsic antibacterial activity, providing new insights in the mode of action of lysins with intrinsic activity against Gram-negative bacteria.

Isolation and characterization of mercury-resistant bacteria from wastewater sources in Egypt.

An important mechanism for microbial resistance to mercury is its reduction into elemental mercury (facilitated by the merA gene). Thirty-eight microbial isolates from a variety of wastewater sources in Egypt were collected. Approximately 14 of the 38 isolates exhibited not only a high degree of tolerance to mercury (up to 160 ppm) but also a high degree of resistance to other tested heavy metals (Cu, Co, Ni, and Zn). From these 14, the 10 most resistant isolates were selected for further study and were found to include 9 Gram-negative and 1 Gram-positive bacterial strains. Multi-antibiotic-resistance profiles were detected for 6 out of the 10 selected isolates. All the tested Gram-negative isolates (n = 9) harbored a plasmid-encoded merA gene. The mercury removal effectiveness for the 10 selected isolates ranged between 50% and 99.9%, among which Stenotrophomonas maltophilia ADW10 recorded the highest rate (99.9%; at an initial mercury concentration of 20 ppm). To the best of our knowledge, this is the first study to (i) demonstrate the presence of a multimetal-resistant S. maltophilia bacterium with a high mercury tolerance capacity that would make it a suitable candidate for future bioremediation efforts in heavy-metal-polluted areas in Egypt and (ii) report Pseudomonas otitidis as one of the mercury-resistant bacteria.

Nuclear trafficking, histone cleavage and induction of apoptosis by the meningococcal App and MspA autotransporters.

Neisseria meningitidis, a major cause of bacterial meningitis and septicaemia, secretes multiple virulence factors, including the adhesion and penetration protein (App) and meningococcal serine protease A (MspA). Both are conserved, immunogenic, type Va autotransporters harbouring S6-family serine endopeptidase domains. Previous work suggested that both could mediate adherence to human cells, but their precise contribution to meningococcal pathogenesis was unclear. Here, we confirm that App and MspA are in vivo virulence factors since human CD46-expressing transgenic mice infected with meningococcal mutants lacking App, MspA or both had improved survival rates compared with mice infected with wild type. Confocal imaging showed that App and MspA were internalized by human cells and trafficked to the nucleus. Cross-linking and enzyme-linked immuno assay (ELISA) confirmed that mannose receptor (MR), transferrin receptor 1 (TfR1) and histones interact with MspA and App. Dendritic cell (DC) uptake could be blocked using mannan and transferrin, the specific physiological ligands for MR and TfR1, whereas in vitro clipping assays confirmed the ability of both proteins to proteolytically cleave the core histone H3. Finally, we show that App and MspA induce a dose-dependent increase in DC death via caspase-dependent apoptosis. Our data provide novel insights into the roles of App and MspA in meningococcal infection.

Genome sequencing of Enterococcus faecium NT04, an oral microbiota revealed the production of enterocin A/B active against oral pathogens.

Objective: This study aimed to isolate and investigate a bacterium from an Egyptian adult's healthy oral cavity, focusing on its probiotic properties, especially its antagonistic activity against oral pathogens. Methods: The isolated bacterium NT04 using 16S rRNA gene sequencing, was identified as Enterococcus faecium. In this study, the whole genome of Enterococcus faecium NT04 was sequenced and annotated by bioinformatics analysis tools. Results: Numerous genes encoding the production of diverse metabolic and probiotic properties, such as bacteriocin-like inhibitory substances (Enterocin A and B), cofactors, antioxidants, and vitamins, were confirmed by genomic analysis. There were no pathogenicity islands or plasmid insertions found. This strain is virulent for host colonization rather than invasion. Conclusion: Genomic characteristics of strain NT04 support its potentiality as an anti-oral pathogen probiotic candidate.

Genomic analysis of Enterococcus durans NT21, a putative bacteriocin-producing isolate.

Enterococcus species are a long-standing and non-pathogenic commensal bacterium, representing an important part of the normal. Enterococcus durans is a rarely isolated species from animals and humans, and it was a tiny constituent of human oral cavity and animal intestinal flora, as well as animal-derived foods, particularly dairy products. This study evaluated the security of our strain E. durans NT21 by using whole-genome sequencing (WGS), physicochemical features, and antimicrobial activity. The complete genomic of our strain Enterococcus durans NT21was sequenced and analyzed by using several bioinformatics tools to identify bacteriocin genes, virulence genes, antibiotic resistance genes, Crispr-Cas and pathogenicity islands. The results showed that our strain NT21 lacks the presence of virulence genes, pathogenicity islands, plasmids and has only two antibiotic resistance genes. On the other hand, it produces three bacteriocin-like inhibitory substances (Enterolysin A, P and L50a). It has six gene-encoded Crisper-Cas and one cluster Crispr-Cas gene. According to our findings, E. durans NT21 is a possible probiotic strain that is safe for both human and animal use.

The Specific Capsule Depolymerase of Phage PMK34 Sensitizes Acinetobacter baumannii to Serum Killing.

The rising antimicrobial resistance is particularly alarming for Acinetobacter baumannii, calling for the discovery and evaluation of alternatives to treat A. baumannii infections. Some bacteriophages produce a structural protein that depolymerizes capsular exopolysaccharide. Such purified depolymerases are considered as novel antivirulence compounds. We identified and characterized a depolymerase (DpoMK34) from Acinetobacter phage vB_AbaP_PMK34 active against the clinical isolate A. baumannii MK34. In silico analysis reveals a modular protein displaying a conserved N-terminal domain for anchoring to the phage tail, and variable central and C-terminal domains for enzymatic activity and specificity. AlphaFold-Multimer predicts a trimeric protein adopting an elongated structure due to a long α-helix, an enzymatic ß-helix domain and a hypervariable 4 amino acid hotspot in the most ultimate loop of the C-terminal domain. In contrast to the tail fiber of phage T3, this hypervariable hotspot appears unrelated with the primary receptor. The functional characterization of DpoMK34 revealed a mesophilic enzyme active up to 50 °C across a wide pH range (4 to 11) and specific for the capsule of A. baumannii MK34. Enzymatic degradation of the A. baumannii MK34 capsule causes a significant drop in phage adsorption from 95% to 9% after 5 min. Although lacking intrinsic antibacterial activity, DpoMK34 renders A. baumannii MK34 fully susceptible to serum killing in a serum concentration dependent manner. Unlike phage PMK34, DpoMK34 does not easily select for resistant mutants either against PMK34 or itself. In sum, DpoMK34 is a potential antivirulence compound that can be included in a depolymerase cocktail to control difficult to treat A. baumannii infections.

Global dynamics of SARS-CoV-2 clades and their relation to COVID-19 epidemiology.

Expansion of COVID-19 worldwide increases interest in unraveling genomic variations of novel SARS-CoV-2 virus. Metadata of 408,493 SARS-CoV-2 genomes submitted to GISAID database were analyzed with respect to genomic clades and their geographic, age, and gender distributions. Of the currently known SARS-CoV-2 clades, clade GR was the most prevalent worldwide followed by GV then GH. Chronological analysis revealed expansion in SARS-CoV-2 clades carrying D614G mutations with the predominance of the newest clade, GV, in the last three months. D614G clades prevail in countries with more COVID-19 cases. Of them, the clades GH and GR were more frequently recovered from severe or deceased COVID-19 cases. In contrast, G and GV clades showed a significantly higher prevalence among asymptomatic patients or those with mild disease. Metadata analysis showed higher (p < 0.05) prevalence of severe/deceased cases among males than females and predominance of GR clade in female patients. Furthermore, severe disease/death was more prevalent (p < 0.05) in elderly than in adults/children. Higher prevalence of the GV clade in children compared to other age groups was also evident. These findings uniquely provide a statistical evidence on the adaptation-driven evolution of SARS-CoV-2 leading to altered infectivity, virulence, and mortality.

Anti-Proliferative and Anti-Biofilm Potentials of Bacteriocins Produced by Non-Pathogenic Enterococcus sp.

The incidence of cancer is increasing worldwide; likewise, the emergence of antibiotic-resistant biofilm-forming pathogens has led to a tremendous increase in morbidity and mortality. This study aimed to evaluate the probiotic properties of bacteriocin-producing Enterococcus sp. with a focus on their anti-biofilm and anticancer activities. Three of 79 Enterococcus isolates (FM43, FM65, FM50) were identified as producers of broad-spectrum bioactive molecules and were molecularly characterized as Enterococcus faecium by 16S rRNA sequencing. Phenotypic and genotypic screening for potential virulence factors revealed no factors known to promote pathogenicity. Treatment with proteinase K resulted in diminished antimicrobial activity; PCR-based screening for bacteriocin genes suggested the presence of both entA and entB genes that encode enterocins A and B, respectively. Maximum antimicrobial activity was detected during the early stationary phase, while activity disappeared after 24 h in culture. Bacteriocins from these isolates were stable at high temperatures and over a wide range of pH. Interestingly, crude supernatants of Ent. faecium FM43 and Ent. faecium FM50 resulted in significant destruction (80% and 48%, respectively; P < 0.05) of Streptococcus mutans ATCC 25175-associated preformed biofilms. Moreover, in vitro cytotoxicity assays revealed that extracts from Ent. faecium isolates FM43, FM65, and FM50 inhibited Caco-2 cell proliferation by 76.9%, 70%, and 85.3%, respectively. Taken together, the multifunctional capabilities of the microbial-derived proteins identified in our study suggest potentially important roles as alternative treatments for biofilm-associated infections and cancer.

Molecular characterization of Extended-spectrum ß lactamase- producing E. coli recovered from community-acquired urinary tract infections in Upper Egypt.

Treatment of community urinary tract infections (UTIs) caused by extended-spectrum ß lactamase (ESBL)- producing Escherichia coli (E. coli) is more expensive than treating ESBL-negative opposites. Evaluation of the prevalence of ESBL-production among urinary E. coli isolates is crucial due to its great impact on the choice of proper antimicrobials. Accordingly, the aim of this work was to detect and characterize ESBL-producing E. coli isolated from outpatients with signs of UTIs in Upper Egypt. Urinary E. coli isolates were identified by 16S rRNA and their ESBL-production was confirmed by Modified Double Disc Synergy Test (MDDST) and ESBL- CHROMagar media. Isolates were then subjected to Polymerase Chain Reaction (PCR) for new Clermont phylogrouping, ESBL genes detection and CTX-M typing. The study enrolled 583 patients with clinically diagnosed UTIs. Uropathogens were found in 400 urine samples (68.6%) out of which 134 E. coli isolates were identified. Among the examined uropathogenic E. coli (UPEC), 80 (59.7%) were recognized as ESBL-producers. Greater than half of the ESBL-producers were multi-drug resistant (MDR) (62%). All of them were susceptible to meropenem. Most of the E. coli isolates were distributed in 4 phylogenetic groups: B2 = 42 (52.5%), F = 17 (21.25%) and Clade I or II = 10 (12.5%). The predominant gene types were TEM 60 (75%) and CTX-M gene 45 (56.25%). The CTX-M-1 group was the most prevalent (62.2%), including the CTX-M-15 enzyme, followed by the CTX-M-2 group, CTX-M-8 group and CTX-M-9 group. In conclusion, the results present alarming evidence of a serious spread of ESBL genes in Egypt, especially the epidemiological CTX-M 15, with the potential for the dissemination of MDR UPEC strains in the community.

Isolation and molecular characterization of multidrug-resistant Escherichia coli from chicken meat.

Antibiotic-resistant Escherichia coli (E. coli) are common in retail poultry products. In this study, we aimed to isolate and characterize multidrug resistant (MDR) E. coli in raw chicken meat samples collected from poultry shops in Sylhet division, Bangladesh, as well as to determine correlation between resistance phenotype and genotype. A total of 600 chicken meat swabs (divided equally between broiler and layer farms, n = 300 each) were collected and the isolates identified as E. coli (n = 381) were selected. Disc diffusion antimicrobial susceptibility assay showed resistance of these isolates to ampicillin, erythromycin, tetracycline, streptomycin, trimethoprim-sulfamethoxazole, chloramphenicol, and gentamicin. Polymerase chain reaction (PCR) identified several antibiotic resistance genes (ARGs) in our isolates. Among these ARGs, the prevalence of tetA (for tetracycline) was the highest (72.58%) in broiler chicken isolates, followed by sul1 (for sulfonamide; 44.16%), aadA1 (for streptomycin; 33.50%), ereA (for erythromycin; 27.41%), aac-3-IV (for gentamicin; 25.38%), and the two genes cmlA (24.87%) and catA1 (8.63%) for chloramphenicol. On the other hand, the respective prevalence in layer chicken isolates were 82.06%, 47.83%, 35.87%, 35.33%, 23.91%, 19.02%, and 5.43%. Furthermore, 49.23% of the isolates from broiler chicken were MDR, with the presence of multiple antibiotic resistance genes, including 3 (40.11%) and 4 (9.13%) genes. On the other hand, 51.09% of layer chicken E. coli isolates were MDR, with 3, 4 or 5 ARGs detected in 36.41%, 14.13%, and 0.54% of the isolates, respectively. We also found that 12.8% of broiler chicken E. coli isolates and 7.61% of layer chicken isolates carried genes coding for extended-spectrum SHV beta-lactamases. Lastly, we report the presence of the AmpC beta-lactamase producing gene (CITM) in 4.56% and 3.26% of broiler and layer chicken E. coli isolates, respectively. We found significant correlations between most of the antimicrobial resistant phenotypes and genotypes observed among the investigated E. coli isolates. Our findings highlight the need for the prudent use of antimicrobials in chickens to minimize the development of antibiotic-resistant bacterial strains.

Two novel synthetic peptides inhibit quorum sensing-dependent biofilm formation and some virulence factors in Pseudomonas aeruginosa PAO1.

Quorum sensing (QS) regulates virulence factor expression in Pseudomonas aeruginosa. Inhibiting the QS-controlled virulence factors without inhibiting the growth of P. aeruginosa is a promising approach for overcoming the widespread resistance of P. aeruginosa. This study was proposed to investigate the effects of two novel synthetic peptides on the biofilm development and virulence factor production of P. aeruginosa. The tested strain was P. aeruginosa PAO1. The results indicated that both of the synthetic peptides (LIVRHK and LIVRRK) inhibited (P < 0.05) the formation of biofilms and the production of virulence factors, including pyocyanin, protease, and rhamnolipids, without inhibiting the growth of PAO1. Additionally, we detected transcriptional changes related to QS and found a significant reduction in the levels of gene expression of lasI, lasR, rhlI, and rhlR. This study demonstrates that LIVRRK and LIVRHK are novel synthetic peptides that can act as potent inhibitors of QS-regulated virulence factors in P. aeruginosa. Moreover, these synthetic peptides have potential applications in the treatment of biofilmrelated diseases. Both peptides may be able to control chronic infections and biofilm-associated problems of P. aeruginosa.

Biological risk assessment of miltefosine in concomitant infection with opportunistic toxoplasmosis.

INTRODUCTION: Although miltefosine is the first line for treatment of leishmaniasis, it could have multiple un-recognized effects if any infection accidentally takes place during therapy. The aim is to precisely evaluate the molecular and biochemical remarks of miltefosine on Toxoplasma gondii accidental infection during miltefosine therapeutic course. METHODOLOGY: changes implied by miltefosine daily parenteral administration to Toxoplasma-infected mice, subcutaneously or intraperitoneal, have been investigated. Tumor necrosis factor-Alfa, immunoglobulin G and M, IL-12 and interferon-gamma release assay (IGRA) were measured in the animals' sera post-miltefosine administration in addition to monitoring Tissue parasite load by measuring the daily changes of copy number of B1 gene using quantitative PCR technique (qPCR). RESULTS: Miltefosine significantly increased inflammatory and immunological markers (TNF-α, IgG and IgM) measured on reference to control untreated group, with a significant increase in the parasite burden and distribution in all tested organs (F = 390.9, df = 9, P < 0.0001), (F = 4478.98, df = 4.75, P< 0.0001) and (F = 247.3, df = 4, P < 0.0001); heart, liver and lung, respectively, using MANOVA. Releasing capability of macrophages significantly increased during the first day of infection, however, it finally declined after seven consecutive doses of miltefosine (t = 7.96, P < 0.001). CONCLUSION: Miltefosine could not control the pathogenesis and multiplication of accidental Toxoplasma infection. Cumulative low parenteral daily doses of miltefosine (1.5 µM) could inversely affected the normal humoral immunity against toxoplasmosis. Therefore, a periodical screening for accidental Toxoplasma infection during the course of therapy is strongly recommended.

Susceptibility and Multidrug Resistance Patterns of Escherichia coli Isolated from Cloacal Swabs of Live Broiler Chickens in Bangladesh.

Antimicrobial resistance is a major health problem, particularly in developing countries like Bangladesh, where there is a paucity of information on resistance patterns and prevalence of antimicrobial determinants. Therefore, the aims of this study were to investigate the prevalence of resistance, including multi-drug resistance (MDR), and the associated genetic determinants in Escherichia coli isolates from cloacal swabs of live broiler chickens in Bangladesh. Altogether, 400 cloacal swabs (200 from Rajshahi and 200 from Dhaka divisions) were randomly collected from individual chickens in 50 broiler farms. E. coli was isolated and identified using conventional bacteriological culture and biochemical methods. The isolates were further confirmed using genus-specific 16S rRNAtargeted polymerase chain reaction (PCR) primers. Antimicrobial susceptibilities and MDR of the isolates against nine different antimicrobial agents (ampicillin, erythromycin, tetracycline, gentamicin, ciprofloxacin, levofloxacin, trimethoprim-sulfamethoxazole, colistin sulphate, and streptomycin) were determined using the Kirby-Bauer disc diffusion method. Resistance determinants of E. coli to ampicillin (blaTEM), streptomycin (aadA1), erythromycin [ere(A)], trimethoprim (dfrA1), and tetracycline [tet(A), tet(B)] were screened using PCR. Our results showed that all swab samples were positive for E. coli. The isolates were uniformly resistant to ampicillin, tetracycline, streptomycin, ciprofloxacin, erythromycin, and trimethoprim-sulphamethoxazole. The isolates exhibited highest susceptibility to colistin sulphate (73.5%), followed by gentamicin (49%), and levofloxacin (17%). All isolates were resistant to three classes of antibiotics, 204 isolates (51%) were resistant to four classes, and 56 isolates (14%) were resistant to five. The highest prevalence of antimicrobial resistance gene was recorded for tetracycline (tet(A):95.25%; tet(B):95.25%) followed by ampicillin (blaTEM:91.25%), streptomycin (aadA1:88.25%), erythromycin (ere(A):84.75%), and trimethoprim (dfrA1:65.5%). In conclusion, surveillance for MDR bacteria in poultry is a critical piece of knowledge, which would be useful for optimizing empiric antimicrobial treatments and exploring alternative antimicrobial agents.

Carriage frequency, phenotypic, and genotypic characteristics of methicillin-resistant Staphylococcus aureus isolated from dental health-care personnel, patients, and environment.

There is limited data on methicillin-resistant Staphylococcus aureus (MRSA) carriage in dental clinics. 1300 specimens from patients, health personnel, and environmental surfaces of a dental clinic in Egypt were tested for MRSA. Antibiotic susceptibility, biofilm formation, Staphylococcal protein A (spa) typing, SCCmec typing, and PCR-based assays were used to detect mecA, mecC, vanA, Panton-Valentine Leukocidin toxin (PVL), and toxic shock syndrome toxin-1 (tst) genes. Among 34 mecA-positive MRSA isolates, five (14.7%) were PVL-positive, seventeen (50%) were tst-positive, ten (29.4%) were vanA-positive, while none harboured mecC. MRSA hand carriage rates in patients, nurses, and dentists were 9.8%, 6.6%, and 5%. The respective nasal colonization rates were 11.1%, 6.7%, and 9.7%. 1.3% of the environmental isolates were MRSA-positive. Strong and moderate biofilm-forming isolates represented 23.5% and 29.4% of MRSA isolates. 24 MRSA isolates (70.6%) were multi-resistant and 18 (52.9%) harboured SCCmec IV. Among eight spa types, t223 (26.5%), t267 (23.5%), and t14339 (23.5%) were predominant. We noted an alarming genetic relatedness between 7 (20.6%) MRSA isolates and the epidemic EMRSA-15 clone, as well as a combined occurrence of tst and PVL in 3 (8.8%) isolates. Results suggest high MRSA pathogenicity in dental wards highlighting the need for more efficient surveillance/infection control strategies.

Enhancement of the productivity of the potent bacteriocin avicin A and improvement of its stability using nanotechnology approaches.

Herein, enhancements of the yield and antimicrobial activity duration of the bacteriocin avicin A were accomplished using fractional factorial design (FFD) and layered double hydroxide (LDH) nanoparticles. Firstly, potential factors affecting bacteriocin production were selected for preliminary study. By a 25-1 FFD, high pH was shown to have a positive effect on avicin A yield, while temperature and duration of incubation, as well as peptone nitrogen sources all had negative effects. The highest bacteriocin production and activity (2560 BU/ml) were observed after 30 h of incubation at 30 °C, with pH adjustment at 7, and in the presence of 2 g mannitol as carbon source and 2.2 g peptone as nitrogen source. Secondly, avicin A nanocomposites with different LDH precursors were tested. Only avicin A-ZnAl-CO3 LDH demonstrated a potent antimicrobial activity against Lactobacillus sakei LMGT 2313 that lasted for at least 24 days, as compared to the values of 6 and 15 days observed with the free avicin A that has been stored at room temperature and at 4 °C, respectively. In conclusion, avicin A production and stability can be improved by manipulating the growth conditions and media composition, together with conjugation to LDHs.

Effects of Selected Egyptian Honeys on the Cellular Ultrastructure and the Gene Expression Profile of Escherichia coli.

The purpose of this study was to: (i) evaluate the antibacterial activities of three Egyptian honeys collected from different floral sources (namely, citrus, clover, and marjoram) against Escherichia coli; (ii) investigate the effects of these honeys on bacterial ultrastructure; and (iii) assess the anti-virulence potential of these honeys, by examining their impacts on the expression of eight selected genes (involved in biofilm formation, quorum sensing, and stress survival) in the test organism. The minimum inhibitory concentration (MIC) of the honey samples against E. coli ATCC 8739 were assessed by the broth microdilution assay in the presence and absence of catalase enzyme. Impacts of the honeys on the cellular ultrastructure and the expression profiles of the selected genes of E. coli were examined using transmission electron microscopy (TEM) and quantitative real-time polymerase chain reaction (qPCR) analysis, respectively. The susceptibility tests showed promising antibacterial activities of all the tested honeys against E. coli. This was supported by the TEM observations, which revealed "ghost" cells lacking DNA, in addition to cells with increased vacuoles, and/or with irregular shrunken cytoplasm. Among the tested honeys, marjoram exhibited the highest total antibacterial activity and the highest levels of peroxide-dependent activity. The qPCR analysis showed that all honey-treated cells share a similar overall pattern of gene expression, with a trend toward reduced expression of the virulence genes of interest. Our results indicate that some varieties of the Egyptian honey have the potential to be effective inhibitor and virulence modulator of E. coli via multiple molecular targets.

Nanotechnology: A Valuable Strategy to Improve Bacteriocin Formulations.

Bacteriocins are proteinaceous antibacterial compounds, produced by diverse bacteria, which have been successfully used as: (i) food biopreservative; (ii) anti-biofilm agents; and (iii) additives or alternatives to the currently existing antibiotics, to minimize the risk of emergence of resistant strains. However, there are several limitations that challenge the use of bacteriocins as biopreservatives/antibacterial agents. One of the most promising avenues to overcome these limitations is the use of nanoformulations. This review highlights the practical difficulties with using bacteriocins to control pathogenic microorganisms, and provides an overview on the role of nanotechnology in improving the antimicrobial activity and the physicochemical properties of these peptides.