Attia, H., R. Szubin, A. S. Yassin, J. M. Monk, and R. K. Aziz, "Draft Genome Sequences of Four Metallo-Beta-Lactamase-Producing Multidrug-Resistant Klebsiella pneumoniae Clinical Isolates, Including Two Colistin-Resistant Strains, from Cairo, Egypt", Microbiology Resource Announcements, vol. 8, no. 7: American Society for Microbiology Journals, 2019. AbstractWebsite

The emergence and spread of metallo-beta-lactamase-producing multidrug-resistant Klebsiella pneumoniae are a serious public health threat. Here, we report the draft genome sequences of four K. pneumoniae strains isolated from Cairo, Egypt, including two panresistant colistin-resistant strains. Genome annotation indicated a number of virulence and resistance genes agreeing with observed phenotypes.

Sheraba, N. S., M. R. Diab, A. S. Yassin, M. A. Amin, and H. H. Zedan, "A Validation study of the Limulus Amebocyte Lysate test as an end-product endotoxin test for Polyvalent Horse Snake Antivenom", PDA Journal of Pharmaceutical Science and Technology, 2019. AbstractWebsite

Snake antivenoms are the only definitive management of snake envenoming's. Endotoxin contamination is a serious threat to the safety of parenteral drugs. A greater understanding of the nature of LAL-Test interferences and the use permissible dilutions has minimized enhancement problems. Common interference mechanisms include suboptimal pH, enzyme or protein modification, and non-specific LAL activation. The study aimed at sorting out the interfering factors before validating the antitoxic sera preparations to avoid false positive results when testing snake venom antiserum samples by (LAL) method. Phase I (Preliminary Screening /Interference Assay) was performed to determine a compatible test dilution, which is then used in Phase II (Inhibition-Enhancement / Validation Study). The results revealed that dilution is the best approach to resolve interferences by a ratio of 1:80 (MVD) plus a specific treatment as heat-activation at 70-80°C for 10 minutes accompanied by rehydration of LAL reagent with Endotoxin Specific Buffer Solution to sort out the enhancement problem.

Eraqi, W. A., M. T. Elrakaiby, S. A. Megahed, N. H. Yousef, M. S. Elshahed, and A. S. Yassin, "The Nile River Microbiome Reveals a Remarkably Stable Community Between Wet and Dry Seasons, and Sampling Sites, in a Large Urban Metropolis (Cairo, Egypt)", OMICS: A Journal of Integrative Biology, vol. 22, no. 8, pp. 553-564, 2018. AbstractWebsite

Abstract World freshwater supplies are in need of microbiome diversity analyses as a first step to future ecological studies, and to monitor water safety and quality. The Nile is a major north-flowing river in Africa that displays both spatial and temporal variations in its water quality. Here, we present the first microbiome analysis of the Nile River water in two seasons: (1) summer representing the wet season, and (2) winter representing the dry season, as sampled around Cairo, the capital of Egypt. Surface river water samples were collected from selected locations along the path of river, and the microbial composition was analyzed by next-generation sequencing of the 16S rRNA gene. We found a striking stability in the Nile microbiome community structure along the examined geographical urban sites and between the wet and dry seasons as evidenced by the high proportion of shared operational taxonomic unit values among all samples. The community was dominated by the Cyanobacteria (mainly Synechococcus), Actinobacteria candidate family (ACK-M1), and Proteobacteria (mainly family Comamonadaceae). Among these dominant taxa, Synechococcus exhibited seasonal driven variation in relative abundance. Other taxa were predominantly rare across all seasons and locations, including genera members of which have been implicated as pathogens such as Acinetobacter, Aeromonas, and Legionella. In addition, comparisons with data on freshwater microbiome in other world regions suggest that surface water communities in large rivers exhibit limited variation. Our results offer the first insights on microbial composition in one of the most notable rivers near a large metropolis.

Rabea, S., M. M. Salem-Bekhit, F. K. Alanazi, A. S. Yassin, N. A. Moneib, and A. G. M. Hashem, "A novel protocol for bacterial ghosts’ preparation using tween 80", Saudi Pharmaceutical Journal, vol. 26, no. 2, pp. 232 - 237, 2018. AbstractWebsite
Hashem, Y. A., H. M. Amin, T. M. Essam, A. S. Yassin, and R. K. Aziz, Biofilm formation in enterococci: genotype-phenotype correlations and inhibition by vancomycin, , vol. 7, issue 1, pp. 5733, 2017. AbstractWebsite

Enterococci are nosocomial pathogens that can form biofilms, which contribute to their virulence and antibiotic resistance. Although many genes involved in biofilm formation have been defined, their distribution among enterococci has not been comprehensively studied on a genome scale, and their diagnostic ability to predict biofilm phenotypes is not fully established. Here, we assessed the biofilm-forming ability of 90 enterococcal clinical isolates. Major patterns of virulence gene distribution in enterococcal genomes were identified, and the differentiating virulence genes were screened by polymerase chain reaction (PCR) in 31 of the clinical isolates. We found that detection of gelE in Enterococcus faecalis is not sufficient to predict gelatinase activity unless fsrAB, or fsrB alone, is PCR-positive (P = 0.0026 and 0.0012, respectively). We also found that agg is significantly enriched in isolates with medium and strong biofilm formation ability (P = 0.0026). Additionally, vancomycin, applied at sub minimal inhibitory concentrations, inhibited biofilm in four out of five strong biofilm-forming isolates. In conclusion, we suggest using agg and fsrB genes, together with the previously established gelE, for better prediction of biofilm strength and gelatinase activity, respectively. Future studies should explore the mechanism of biofilm inhibition by vancomycin and its possible use for antivirulence therapy.

ElKenawy, N. M., A. S. Yassin, H. N. Elhifnawy, and M. A. Amin, "Optimization of prodigiosin production by Serratia marcescens using crude glycerol and enhancing production using gamma radiation", Biotechnology Reports, vol. 14, pp. 47 - 53, 2017. AbstractWebsite
Bahy, R. H., H. M. Hamouda, A. S. Shahat, A. S. Yassin, and M. A. Amin, "Development and evaluation of a novel vaccine against prevalent invasive multi-drug resistant strains of Streptococcus pneumoniae.", PeerJ, vol. 4, pp. e2737, 2016. Abstract

Streptococcus pneumoniae is a pathogen that causes serious invasive infections, such as septicemia, meningitis and pneumonia in addition to mild upper respiratory tract infections. Protection from pneumococcal diseases is thought to be mediated mainly by serotype-specific antibodies to capsular antigens. Pneumococcal conjugate vaccine consists of sugars (polysaccharides) from the capsule of the bacterium S. pneumoniae that are conjugated to a carrier protein. Three pneumococcal conjugated vaccines, each directed against a group of serotypes, are registered in Egypt; however, local vaccine production is required to cover the most prevalent serotypes. In this work, capsular polysaccharide from the most current and prevalent serotypes in Egypt were extracted, purified and conjugated to bovine serum albumin (BSA). The polysaccharide protein conjugate was purified through ultrafiltration technique and molecular size distribution was compared to an available vaccine. The immunogenicity of the prepared vaccine was examined via two methods: First, by measuring the levels of the elicited antibodies in the sera of the vaccinated mice; second, by challenging the vaccinated groups of mice with approximately 10(7) CFU of each specific serotype and determining the degree of protection the developled vaccine offers. Our results show that the developed conjugated capsular polysaccharide vaccine is highly immunogenic and protective in mice. This finding illustrates the importance of tracking the most recent and predominant peneumococcal serotypes to generate effective vaccines, instead of using expensive imported vaccines with large number of serotypes which might not be even present in the community.

Elhosseiny, N. M., O. M. El-Tayeb, A. S. Yassin, S. Lory, and A. S. Attia, "The secretome of Acinetobacter baumannii ATCC 17978 type II secretion system reveals a novel plasmid encoded phospholipase that could be implicated in lung colonization.", International journal of medical microbiology : IJMM, vol. 306, issue 8, pp. 633-641, 2016 Dec. Abstract

Acinetobacter baumannii infections are compounded with a striking lack of treatment options. In many Gram-negative bacteria, secreted proteins play an important early role in avoiding host defences. Typically, these proteins are targeted to the external environment or into host cells using dedicated transport systems. Despite the fact that medically relevant species of Acinetobacter possess a type II secretion system (T2SS), only recently, its significance as an important pathway for delivering virulence factors has gained attention. Using in silico analysis to characterize the genetic determinants of the T2SS, which are found clustered in other organisms, in Acinetobacter species, they appear to have a unique genetic organization and are distributed throughout the genome. When compared to other T2SS orthologs, individual components of the T2SS apparatus showed the highest similarity to those of Pseudomonas aeruginosa. A mutant of Acinetobacter baumannii strain ATCC 17978 lacking the secretin component of the T2SS (ΔgspD), together with a trans-complemented mutant, were tested in a series of in vitro and in vivo assays to determine the role of T2SS in pathogenicity. The ΔgspD mutant displayed decreased lipolytic activity, associated with attenuated colonization ability in a murine pneumonia model. These phenotypes are linked to LipAN, a novel plasmid-encoded phospholipase, identified through mass spectroscopy as a T2SS substrate. Recombinant LipAN showed specific phospholipase activity in vitro. Proteomics on the T2-dependent secretome of ATCC 17978 strain revealed its potential dedication to the secretion of a number of lipolytic enzymes, among others which could contribute to its virulence. This study highlights the role of T2SS as an active contributor to the virulence of A. baumannii potentially through secretion of a newly identified phospholipase.

Bahy, R. H., H. M. Hamouda, A. S. Shahat, A. S. Yassin, and M. A. Amin, "Emergence of Neoteric Serotypes Among Multidrug Resistant Strains of Streptococcus pneumoniae Prevalent in Egypt", Jundishapur J Microbiol, vol. 9, no. 4, pp. e30708, 2016. AbstractWebsite
Eraqi, W. A., A. S. Yassin, A. E. Ali, and M. A. Amin, "Utilization of Crude Glycerol as a Substrate for the Production of Rhamnolipid by Pseudomonas aeruginosa", Biotechnology Research International, vol. 2016, pp. 9, 2016. Abstract