Browsing by Author "Amin, Heba M"

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1,2 Propanediol utilization by Lactobacillus reuteri DSM 20016, role in bioconversion of glycerol to 1,3 propanediol, 3-hydroxypropionaldehyde and 3-hydroxypropionic acid
(ELSEVIER, 06/01/2013) Amin, Heba M; Hashem, Abdelgawad M; Ashour, Mohamed S; Hatti-Kaul, Rajini
The objective of the presented work is to demonstrate the metabolism of 1,2 propandiol by Lactobacillus reuteri and to elucidate the metabolites produced during the process. This Metabolic pathway is crucial for biotechnological applications using L. reuteri in bioconversion of glycerol to industrially important plate-form chemicals. L. reuteri grown on minimal media containing 1,2 propanediol was able to utilize the compound as a sole carbon and energy source. The growth of the bacteria was linear with time; however the specific growth rate was significantly low compared to bacteria grown on the same media in the presence of glucose.
High risk of potential diarrheagenic Bacillus cereus in diverse food products in Egypt
(Allen press, 1/19/2020) Amin, Heba M; Tawfick, Mahmoud M
Bacillus cereus is one of the important foodborne pathogens that can be found in various foodstuffs; causing diarrheal and/or emetic syndromes. This study aimed to evaluate the prevalence, antimicrobial susceptibility profile, pathogenic potential, and genotypic diversity of B. cereus isolated from diverse food products from markets in Cairo, Egypt. A total of 39 out of 165 food samples were positive for B. cereus (detection rate of 24%) with a contamination level ranged from 2 to 6 log CFU/g and a higher incidence of > 3 log bacterial count. Antimicrobial susceptibility testing showed that B. cereus isolates were fully sensitive to all tested antimicrobial agents except β-lactams. The pathogenic potential of the 39 B. cereus isolates was assessed by detecting and profiling the secreted virulence or toxin encoding genes including the chromosomal-carried genes hblA , bceT , plc , sph , nheA , entFM , cytK associated with the diarrheal syndrome and the plasmid-carried ces gene associated with the emetic syndrome. The most frequently detected genes were hblA , nheA and entFM . All isolates harbored more than one of the diarrheal enterotoxins encoding genes with the genetic profile hblA-bceT-nheA-entFM-cytK-plc-sph was the most prevalent (in 20/39 isolates). The emetic toxin ces was not detected at all. ERIC-based analysis of the 20 B. cereus isolates harboring the prevalent genetic profile revelated that they were genetically distinct. In conclusion, the findings of this study provide useful information for public health management and serve as a warning of the potential risk of diarrheagenic B. cereus in diverse food products. Therefore, the consideration to extensively study the epidemiology of this food pathogen in Egypt is warranted. Additionally, strict procedures should be applied to monitor, protect, and safely handle food products, particularly ready to eat foodstuffs that are usually consumed without heat treatment.
In Silico and In Vitro Investigation of the Distribution and Expression of Key Genes in the Fucose Operon of Escherichia coli
(MDPI AG, 2023-05) Saif, Nehal A; Hashem, Yomna A; Amin, Heba M; Aziz, Ramy K
Many gut bacteria degrade polysaccharides, providing nutritional advantages to their hosts. Fucose, a mucin degradation product, was suggested as a communication molecule between the resident microbiota and external pathogens. However, the precise role and variants of the fucose utilization pathway remain to be elucidated. Here, we computationally and experimentally investigated the fucose utilization operon of E. coli. While the operon is conserved among E. coli genomes, a variant pathway, in which an ABC transporter system replaces the fucose permease gene (fucP), was computationally identified in 50 out of 1058 genomes. Comparative genomics and subsystems analysis results were confirmed by polymerase chain reaction-based screening of 40 human E. coli isolates, which indicated the conservation of fucP in 92.5% of the isolates (vs. 7.5% of its suggested alternative, yjfF). The in silico predictions were confirmed by in vitro experiments comparing the growth of E. coli strains K12, BL21, and isogenic fucose-utilization K12 mutants. Additionally, fucP and fucI transcripts were quantified in E. coli K12 and BL21, after in silico analysis of their expression in 483 public transcriptomes. In conclusion, E. coli utilizes fucose by two pathway variants, with measurable transcriptional differences. Future studies will explore this variation’s impact on signaling and virulence.
Occurrence and Molecular Study of Hypermucoviscous/Hypervirulence Trait in Gut Commensal K. pneumoniae from Healthy Subjects
(MDPI AG, 2023-04) Osama, Dina M; Zaki, Bishoy M; Khalaf, Wafaa S; Mohamed, Marwa Yousry A; Tawfick, Mahmoud M; Amin, Heba M
Hypervirulent Klebsiella pneumoniae (hvKp) is emerging worldwide. Hypermucoviscousity is the characteristic trait that distinguishes it from classic K. pneumoniae (cKp), which enables Kp to cause severe invasive infections. This research aimed to investigate the hypermucoviscous Kp (hmvKp) phenotype among gut commensal Kp isolated from healthy individuals and attempted to characterize the genes encoding virulence factors that may regulate the hypermucoviscosity trait. Using the string test, 50 identified Kp isolates from healthy individuals’ stool samples were examined for hypermucoviscosity and investigated by transmission electron microscopy (TEM). Antimicrobial susceptibility profiles of Kp isolates were determined using the Kirby Bauer disc method. Kp isolates were tested for genes encoding different virulence factors by PCR. Biofilm formation was assayed by the microtiter plate method. All Kp isolates were multidrug-resistant (MDR). Phenotypically, 42% of isolates were hmvKp. PCR-based genotypic testing revealed the hmvKp isolates belonged to capsular serotype K2. All study Kp isolates harbored more than one virulence gene. The genes magA and rmpA were not detected, while the terW gene was present in all isolates. The siderophores encoding genes entB and irp2 were most prevalent in hmvKp isolates (90.5%) and non-hmvKp (96.6%), respectively. hmvKp isolates harbored the genes wabG and uge with rates of 90.5% and 85.7%, respectively. The outcomes of this research highlight the potential health risk of commensal Kp to cause severe invasive diseases, owing to being hmvKp and MDR, and harboring multiple virulence genes. The absence of essential genes related to hypermucoviscosity such as magA and rmpA in hmvKp phenotypes suggests the multifactorial complexity of the hypermucoviscosity or hypervirulence traits. Thus, further studies are warranted to verify the hypermucoviscosity-related virulence factors among pathogenic and commensal Kp in different colonization niches.
Production of highly immunogenic and safe Triton X-100 produced bacterial ghost vaccine against Shigella fexneri 2b serotype
(BioMed Central Ltd., 2023-08) Abdelfattah, Amany; Samir, Reham; Amin, Heba M
Background Bacterial ghost cells (BGCs) are cells were drained of their genetic and cytoplasmic components. This work aimed to develop vaccine candidates against the Shigella fexneri (S. fexneri) 2b serotype using the BGCs approach. For the frst time, (S. fexneri) 2b serotype BGCs vaccine was prepared by incubation with Triton X-100 (TX100) for only 12 h. Its safety and immunogenicity were compared to another vaccine produced using a previously used surfactant, namely Tween 80 (TW80). Scanning electron microscopy (SEM), cellular DNA, protein contents meas- urements, and ghost cell re-cultivation were used to confrm the successful generation of the BGCs. Immunogenic- ity was assessed through mice’s intraperitoneal (IP) immunization followed by infection with S. fexneri ATCC 12022. Finally, histopathological examination was carried out. Results Viable colony forming units (CFUs) of S. fexneri were counted from stool samples as well as homogenized colon tissues of the non-immunized challenged group. Immunized mice sera showed a signifcant increase in serum bactericidal activity of both preparations (TX100=40% and TW80=56%) compared to the non-immunized chal- lenged group (positive control). The IgG levels of the bacterial ghost-vaccinated groups were four and three times greater for the TX100 and TW80 ghost vaccines, respectively, compared to that of the positive control; both bac- terial ghost vaccines (BGVs) were safe and efective, according to the results of the safety check tests and histopatho- logical analysis. Conclusions When comparing the BGVs prepared using TX100 and TW80 methods, the use of TX100 as a new chemical treating agent for BGC production attained robust results in terms of shorter incubation time with the tar- geted cells and a strong immune response against S. fexneri 2b serotype ATCC 12022 in the IP challenge test. How- ever, a clinical study is needed to confrm the efcacy and total safety of this novel vaccine.
Resistome, mobilome, and virulome explored in clinical isolates derived from acne patients in Egypt: unveiling unique traits of an emerging coagulase-negative Staphylococcus pathogen
(Frontiers Media S.A., 2024-02) Amer, Mai A; Darwish, Manal M; Soliman, Noha S; Amin, Heba M
Coagulase-negative staphylococci (CoNS) are a group of gram-positive staphylococcal species that naturally inhabit the healthy human skin and mucosa. The clinical impact of CoNS-associated infections has recently been regarded as a challenge for diagnosis and therapeutic options. CoNS-associated infections are primarily caused by bacterial resistance to antibiotics and biofilm formation. As antibiotics are still the most used treatment, this problem will likely persist in the future. The present study aimed to investigate the resistance and virulence of CoNS recovered from various acne lesions and explore their genetic basis. Skin swab samples were collected from participants with acne and healthy skin. All samples underwent conventional culture for the isolation of CoNS, MALDI-TOF confirmation, antibiotic susceptibility, and biofilm formation testing. A total of 85 CoNS isolates were recovered from the samples and preliminarily identified as Staphylococcus epidermidis. Isolates from the acne group (n = 60) showed the highest rates of resistance to penicillin (73%), cefoxitin (63%), clindamycin (53.3%), and erythromycin (48%), followed by levofloxacin (36.7%) and gentamycin (31.7%). The lowest rates of resistance were observed against tetracycline (28.3%), doxycycline (11.7%), and minocycline (8.3%). CoNS isolated from mild, moderate acne and healthy isolates did not show strong biofilm formation, whereas the isolates from the severe cases of the acne group showed strong biofilm formation (76.6%). Four extensively drug-resistant and strong biofilm-forming staphylococcal isolates recovered from patients with severe acne were selected for whole-genome sequencing (WGS), and their genomes were investigated using bioinformatics tools. Three of the sequenced genomes were identified as S. epidermidis; however, isolate 29AM was identified as Staphylococcus warneri, which is a newly emerging pathogen that is not commonly associated with acne and was not detected by MALDI-TOF. All the sequenced strains were multidrug-resistant and carried multiple resistance genes, including blaZ, mecA, tet(K), erm(C), lnuA, vgaA, dfrC, fusB, fosBx1, norA,and vanT, which were found to be located on plasmids and chromosomes. Virulence features were detected in all genomes in the presence of genes involved in adherence and biofilm formation (icaA, icaB, icaC, sdrG, sdrH, atl, ebh, and ebp). Only the S. warneri isolate 29AM contained immune evasion genes (capB, capC, acpXL, and manA), an anti-phagocytosis gene (cdsA), and other unique features. As a result of their potential pathogenicity and antibiotic resistance, CoNS must be monitored as an emerging pathogen associated with acne infections. To the best of our knowledge, this is the first report to isolate, identify, and correlate S. warneri with severe acne infections among Egyptian patients using WGS and bioinformatic analysis.