Mohamed Samir

Dr. Mohamed Samir

Immunogenetics, The Pirbright Institute, Woking, Surrey, UK
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Research Focus & Metrics

Academic Career Length

12Years (2015-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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8 February 2022 in Frontiers in Microbiology
Verified
Journal Article
Open access
TSTaisir Saber
Taisir Saber
Mohamed SamirMohamed Samir
Mohamed Samir
RERasha M. El-Mekkawy
Rasha M. El-Mekkawy
EAEman Ariny
Eman Ariny
SESara Ramadan El-Sayed
Sara Ramadan El-Sayed
YTYasmine Hasanine Tartor
Yasmine Hasanine Tartor
Methicillin-resistant and vancomycin-resistant Staphylococcus aureus (MRSA and VRSA) are zoonotic life-threatening pathogens, and their presence in food raises a public health concern. Yet, scarce data are available regarding MRSA and VRSA in both ready-to-eat (RTE) meat and food handlers. This study was undertaken to determine the frequency, antimicrobial resistance, and biofilm-forming ability of MRSA and VRSA isolated from RTE meat (shawarma and burger) and humans (food handlers, and hospitalized patients) in Zagazig city, Sharkia Governorate, Egypt. We analyzed 176 samples (112 human samples: 72 from hospitalized patients and 40 from food handlers, 64 RTE meat samples: 38 from shawarma and 26 from burger). Using phenotypic, PCR-based identification of nuc gene and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), 60 coagulase-positive S. aureus (COPS) isolates were identified in the samples as follow: RTE meat (15/64, 23.4%), hospitalized patients (33/72, 45.8%) and food handlers (12/40, 30%). All the COPS isolates were mecA positive (and thus were classified as MRSA) and multidrug resistant with multiple antibiotic resistance indices ranging from 0.25 to 0.92. Overall, resistance to cefepime (96.7%), penicillin (88.3%), were common, followed by ampicillin-sulbactam (65%), ciprofloxacin (55%), nitrofurontoin (51.7%), and gentamicin (43.3%). VRSA was detected in 30.3% of COPS hospitalized patient’s isolates, 26.7% of COPS RTE meat isolates and 25% of COPS food handler’s isolates. VanA, vanB, or both genes were detected in 64.7, 5.9, and 29.4% of all VAN-resistant isolates, respectively. The majority of the COPS isolates (50/60, 83.3%) have biofilm formation ability and harbored icaA (76%), icaD (74%), icaC (50%), and icaB (46%) biofilm-forming genes. The bap gene was not detected in any of the isolates. The ability of MRSA and VRSA isolates to produce biofilms in addition to being resistant to antimicrobials highlight the danger posed by these potentially virulent microorganisms persisting in RTE meat, food handlers, and patients. Taken together, good hygiene practices and antimicrobial surveillance plans should be strictly implemented along the food chain to reduce the risk of colonization and dissemination of MRSA and VRSA biofilm-producing strains.

17 February 2018 in Journal of Applied Microbiology
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Journal Article
Open access
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Hazem RamadanHazem Ramadan
Hazem Ramadan
NIN. Ibrahim
N. Ibrahim
Mohamed SamirMohamed Samir
Mohamed Samir
AEA. Abd El-Moaty
A. Abd El-Moaty
TGT. Gad
T. Gad
Aims Aeromonas hydrophila has been isolated from various fish species in Egypt and is known to carry virulence and antimicrobial resistance genes, which pose a risk for public health. The aim of the present study is to report, for the first time, the infection of mullet (Mugil cephalus) with A. hydrophila and to clarify the potential association between antimicrobial resistance and virulence traits encoded in A. hydrophila. Methods and Results In this study, the occurrence of A. hydrophila in marketed mullet and the antimicrobial resistance phenotypes of these isolates were determined. Aeromonas hydrophila isolates were screened for the presence of virulence and β-lactam resistance genes; the correlation between both gene groups was also investigated. The infection rate of examined mullet with A. hydrophila was 37% (50/135). The highest antimicrobial resistance was detected to cefoxitin (100%), followed by ampicillin (84%), ceftazidime (56%) and cefotaxime (40%). Only 4% of the isolates were resistant to erythromycin; 6% were resistant to both gentamicin and kanamycin with no resistance to ciprofloxacin. Variable frequencies of virulence and β-lactam resistance genes were evident from PCR, where aerA and blaTEM predominated. The study also indicated a general weak positive correlation (R = 0·3) between both virulence and β-lactam resistance genes. Some of the studied virulence genes (e.g. aerA:hlyA and hlyA:ast) were found to correlate positively. Conclusions The presence of virulence and resistance genes in A. hydrophila from food sources poses a serious threat to public health. To our knowledge, this is the first report describing the occurrence of A. hydrophila in mullet and highlighting the coexistence of virulence and β-lactam resistance genes encoded by these bacteria. Significance and Impact of the Study These data provide insights into the potential association of antimicrobial resistance and virulence genes in A. hydrophila from marketed mullet in Egypt, which could pose threats to humans even if a weak positive correlation exists between both genes.

24 December 2019 in mBio
Verified
Journal Article
Open access
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LALeonardo Silva de Araujo
Leonardo Silva de Araujo
MRMarcelo Ribeiro-Alves
Marcelo Ribeiro-Alves
TLThyago Leal-Calvo
Thyago Leal-Calvo
JLJanaína Leung
Janaína Leung
VDVerónica Durán
Verónica Durán
Frank PesslerFrank Pessler
Frank Pessler
In tuberculosis (TB), as in other infectious diseases, studies of small noncoding RNAs (sncRNA) in peripheral blood have focused on microRNAs (miRNAs) but have neglected the other major sncRNA classes in spite of their potential functions in host gene regulation. Using RNA sequencing of whole blood, we have therefore determined expression of miRNA, PIWI-interacting RNA (piRNA), small nucleolar RNA (snoRNA), and small nuclear RNA (snRNA) in patients with TB (n = 8), latent TB infection (LTBI; n = 21), and treated LTBI (LTBItt; n = 6) and in uninfected exposed controls (ExC; n = 14). As expected, sncRNA reprogramming was greater in TB than in LTBI, with the greatest changes seen in miRNA populations. However, substantial dynamics were also evident in piRNA and snoRNA populations. One miRNA and 2 piRNAs were identified as moderately accurate (area under the curve [AUC] = 0.70 to 0.74) biomarkers for LTBI, as were 1 miRNA, 1 piRNA, and 2 snoRNAs (AUC = 0.79 to 0.91) for accomplished LTBI treatment. Logistic regression identified the combination of 4 sncRNA (let-7a-5p, miR-589-5p, miR-196b-5p, and SNORD104) as a highly sensitive (100%) classifier to discriminate TB from all non-TB groups. Notably, it reclassified 8 presumed LTBI cases as TB cases, 5 of which turned out to have features of Mycobacterium tuberculosis infection on chest radiographs. SNORD104 expression decreased during M. tuberculosis infection of primary human peripheral blood mononuclear cells (PBMC) and M2-like (P = 0.03) but not M1-like (P = 0.31) macrophages, suggesting that its downregulation in peripheral blood in TB is biologically relevant. Taken together, the results demonstrate that snoRNA and piRNA should be considered in addition to miRNA as biomarkers and pathogenesis factors in the various stages of TB. IMPORTANCE Tuberculosis is the infectious disease with the worldwide largest disease burden and there remains a great need for better diagnostic biomarkers to detect latent and active M. tuberculosis infection. RNA molecules hold great promise in this regard, as their levels of expression may differ considerably between infected and uninfected subjects. We have measured expression changes in the four major classes of small noncoding RNAs in blood samples from patients with different stages of TB infection. We found that, in addition to miRNAs (which are known to be highly regulated in blood cells from TB patients), expression of piRNA and snoRNA is greatly altered in both latent and active TB, yielding promising biomarkers. Even though the functions of many sncRNA other than miRNA are still poorly understood, our results strongly suggest that at least piRNA and snoRNA populations may represent hitherto underappreciated players in the different stages of TB infection.

8 May 2020 in Pathogens
Verified
Journal Article
Open access
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Hazem RamadanHazem Ramadan
Hazem Ramadan
CJCharlene Jackson
Charlene Jackson
Jonathan FryeJonathan Frye
Jonathan Frye
LHLari M. Hiott
Lari M. Hiott
Mohamed SamirMohamed Samir
Mohamed Samir
TWTiffanie A. Woodley
Tiffanie A. Woodley
Contamination of retail foods with foodborne pathogens, particularly the antimicrobial resistant ones, poses a persistent threat to human health. There is a dearth of information about the overlapping Escherichia coli (E. coli) lineages circulating among retail foods and humans in Egypt. This study aimed to determine the clonal diversity of 120 E. coli isolates from diarrheic patients (n = 32), retail chicken carcasses (n = 61) and ground beef (n = 27) from Mansoura, Egypt using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Simpson’s index of diversity was calculated to compare the results of both typing methods. Antimicrobial resistance phenotypes, genotypes and phylogrouping of the isolates were also determined. Higher frequencies of antimicrobial resistance were found among chicken isolates compared to beef and human isolates; regardless of isolate source, the predominant antimicrobial resistances were found against ampicillin (87/120, 72.5%), tetracycline and sulfisoxazole (82/120, 68.3%, each), and streptomycin (79/120, 65.8%). None of the isolates displayed resistance to meropenem. The prevalent genes detected were tetA (64.2%), blaTEM (62.5%), sul1 (56.7%), floR (53.3%), sul2 (50%), strB (48.3%) and strA (47.5%) corresponding with resistance phenotypes. Alarmingly, blaCTX was detected in 63.9% (39/61) of chicken isolates. The majority of E. coli isolates from humans (90.6%), beef (81.5%) and chicken (70.5%) belonged to commensal phylogroups (A, B1, C). Using PFGE analysis, 16 out of 24 clusters (66.7%) contained isolates from different sources at a similarity level ≥75%. MLST results assigned E. coli isolates into 25, 19 and 13 sequence types (STs) from chicken, human and beef isolates, respectively. Six shared STs were identified including ST1011, ST156, ST48, ST224 (chicken and beef), ST10 (human and chicken) and ST226 (human and beef). Simpson’s index of diversity was higher for MLST (0.98) than PFGE (0.94). In conclusion, the existence of common genetic determinants among isolates from retail foods and humans in Egypt as well as the circulation of shared STs indicates a possible epidemiological link with potential zoonotic hazards.

1 October 2021 in Journal of Infection and Public Health
Verified
Journal Article
Open access
RARania Mohamed Amer
Rania Mohamed Amer
Mohamed SamirMohamed Samir
Mohamed Samir
OGOsama A. Gaber
Osama A. Gaber
NENahawand A. El-Deeb
Nahawand A. El-Deeb
AAAhmed A. Abdelmoaty
Ahmed A. Abdelmoaty
RAReham H. Anis
Reham H. Anis
Egypt was among the first 10 countries in Africa that experienced COVID-19 cases. The sudden surge in the number of cases is overwhelming the capacity of the national healthcare system, particularly in developing countries. Central to the containment of the ongoing pandemic is the availability of rapid and accurate diagnostic tests that could pinpoint patients at early disease stages. In the current study, we aimed to (1) Evaluate the diagnostic performance of the rapid antigen test (RAT) “Standard™ Q COVID-19 Ag” against reverse transcriptase quantitative real-time PCR (RT-qPCR) in eighty-three swabs collected from COVID-19 suspected individuals showing various demographic features, clinical and radiological findings. (2) Test whether measuring laboratory parameters in participant’s blood would enhance the predictive accuracy of RAT. (3) Identify the most important features that determine the results of both RAT and RT-qPCR. Diagnostic measurements (e.g. sensitivity, specificity, etc.) and receiver operating characteristic curve was used to assess the clinical performance of “Standard™ Q COVID-19 Ag”. We used the support vector machine (SVM) model to investigate whether measuring laboratory indices would enhance the accuracy of RAT. Moreover, a random forest classification model was used to determine the most important determinants of the results of RAT and RT-qPCR for COVID-19 diagnosis. The sensitivity, specificity, and accuracy of RAT were 78.2, 64.2, and 75.9%, respectively. Samples with high viral load and those that were collected within one-week post-symptoms showed the highest sensitivity and accuracy. The SVM modeling showed that measuring laboratory indices did not enhance the predictive accuracy of RAT. “Standard™ Q COVID-19 Ag” should not be used alone for COVID-19 diagnosis due to its low diagnostic performance relative to the RT-qPCR. RAT is best used at the early disease stage and in patients with high viral load.

18 October 2019 in Frontiers in Microbiology
Verified
Journal Article
Open access
PDF file
MEMarwa I. Abd El-Hamid
Marwa I. Abd El-Hamid
NENorhan Abd El-Aziz
Norhan Abd El-Aziz
Mohamed SamirMohamed Samir
Mohamed Samir
EEEl-Sayed Y. El-Naenaeey
El-Sayed Y. El-Naenaeey
EREtab M. Abo Remela
Etab M. Abo Remela
MAMohammad Alsanea
Mohammad Alsanea
Campylobacter jejuni (C. jejuni) are able to colonise and infect domestic poultry and also pose a risk for humans. The aim of this study was to determine the extent of genotypic diversity among C. jejuni isolates recovered from avian and human sources in Egypt. Furthermore, the short variable region (SVR) of flagellin A (flaA) gene was analysed for the presence of allelic variants. Our results showed that C. jejuni isolates differ in their capacity to harbour each of the virulence genes alone or when present in various combinations. The flaA gene was detected in all C. jejuni strains and none of the strains had all the studied virulence genes together. When considering C. jejuni strains from the investigated sources, the cdtC gene was the most similar, while the cdtB and iam genes were the most dissimilar. We could identify 13 novel alleles in the analysed strains. The analyses of virulence gene patterns, flaA gene sequences and allelic variants showed that C. jejuni strains from different sources overlapped largely suggesting potential involvement of poultry in transmitting C. jejuni to humans. We also found that the strains isolated from the same host were highly heterogeneous, with chicken strains exhibiting the highest diversity. Moreover, the human strains were clustered closer to chicken ones than to those from pigeon. The results of this study should be taken into consideration when assessing the epidemiology and risk potential of Egyptian C. jejuni not only in poultry, but also in humans.