Abdallah M. A. Merwad

Dr. Abdallah M. A. Merwad


Research Focus & Metrics

Academic Career Length

17Years (2010-Present)

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

Representative Publications

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1 January 2018 in Veterinary Quarterly
Verified
Journal Article
Open access
EHEmad Hashish
Emad Hashish
AMAbdallah M. A. Merwad
Abdallah M. A. Merwad
SEShimaa Elgaml
Shimaa Elgaml
AAAli Amer
Ali Amer
HKHuda Kamal
Huda Kamal
MSMahmoud Sitohy
Mahmoud Sitohy
Mycobacterium marinum is an opportunistic pathogen inducing infection in fresh and marine water fish. This pathogen causes necrotizing granuloma like tuberculosis, morbidity and mortality in fish. The cell wall-associated lipid phthiocerol dimycocerosates, phenolic glycolipids and ESAT-6 secretion system 1 (ESX-1) are the conserved virulence determinant of the organism. Human infections with Mycobacterium marinum hypothetically are classified into four clinical categories (type I–type IV) and have been associated with the exposure of damaged skin to polluted water from fish pools or contacting objects contaminated with infected fish. Fish mycobacteriosis is clinically manifested and characterized in man by purple painless nodules, liable to develop into superficial crusting ulceration with scar formation. Early laboratory diagnosis of M. marinum including histopathology, culture and PCR is essential and critical as the clinical response to antibiotics requires months to be attained. The pathogenicity and virulence determinants of M. marinum need to be thoroughly and comprehensively investigated and understood. In spite of accumulating information on this pathogen, the different relevant data should be compared, connected and globally compiled. This article is reviewing the epidemiology, virulence factors, diagnosis and disease management in fish while casting light on the potential associated public health hazards.

10 March 2023 in Biology
Verified
Journal Article
Open access
PDF file
DEDalia El-Hossary
Dalia El-Hossary
AMAsmaa Mahdy
Asmaa Mahdy
EEEman Y. T. Elariny
Eman Y. T. Elariny
AAAhmed Askora
Ahmed Askora
AMAbdallah M. A. Merwad
Abdallah M. A. Merwad
RArehab atef
rehab atef
The genus Aeromonas is widely distributed in aquatic environments and is recognized as a potential human pathogen. Some Aeromonas species are able to cause a wide spectrum of diseases, mainly gastroenteritis, skin and soft-tissue infections, bacteremia, and sepsis. The aim of the current study was to determine the prevalence of Aeromonas spp. in raw fish markets and humans in Zagazig, Egypt; identify the factors that contribute to virulence; determine the isolates’ profile of antibiotic resistance; and to elucidate the ability of Aeromonas spp. to form biofilms. The examined samples included fish tissues and organs from tilapia (Oreochromis niloticus, n = 160) and mugil (Mugil cephalus, n = 105), and human skin swabs (n = 51) and fecal samples (n = 27). Based on biochemical and PCR assays, 11 isolates (3.2%) were confirmed as Aeromonas spp. and four isolates (1.2%) were confirmed as A. hydrophila. The virulence genes including haemolysin (hyl A) and aerolysin (aer) were detected using PCR in A. hydrophila in percentages of 25% and 50%, respectively. The antimicrobial resistance of Aeromonas spp. was assessed against 14 antibiotics comprising six classes. The resistance to cefixime (81.8%) and tobramycin (45.4%) was observed. The multiple antibiotic resistance (MAR) index ranged between 0.142–0.642 with 64.2% of the isolates having MAR values equal to 0.642. Biofilm formation capacity was assessed using a microtiter plate assay, and two isolates (18.1%) were classified as biofilm producers. This study establishes a baseline for monitoring and controlling the multidrug-resistant Aeromonas spp. and especially A. hydrophila in marine foods consumed in our country to protect humans and animals.

20 March 2019 in Transboundary and Emerging Diseases
Verified
Journal Article
Closed access
PDF file
Marwa Abd El-HamidMarwa Abd El-Hamid
Marwa Abd El-Hamid
MAMohammad Alsanea
Mohammad Alsanea
AMAbdallah M. A. Merwad
Abdallah M. A. Merwad
Ibrahim ElsohabyIbrahim Elsohaby
Ibrahim Elsohaby
DGDoaa Ghaith
Doaa Ghaith
Walaa AlshareefWalaa Alshareef
Walaa Alshareef
Methicillin resistant Staphylococcus aureus (MRSA) has been shown to be the predominant life‐threatening pathogen in Egypt. MRSA is a major cause of severe healthcare‐associated (HA) infections. During the last decades, the incidence of community‐associated (CA) MRSA infections has a complex epidemiology arising from the circulation of different strains in the general population. Moreover, livestock‐associated (LA) MRSA emerged recently becomes an emerging threat to public health. Therefore, it's important to illuminate the differences between CA‐, HA and LA‐MRSA to shed light on their genetic diversity and evolution.This study presents the first data on analyzing the correlation between CA‐, LA‐ and HA‐MRSA using antibiogram typing, molecular characteristics and antimicrobial resistance and virulence genes' profiles. Overall, HA‐MRSA strains tended to be multidrug resistant and less virulent than both LA‐and CA‐ MRSA strains. Importantly, CA‐MRSA strains had a high homology with each of HA‐and LA‐MRSA. However, no similarity was observed between HA‐ and LA‐MRSA. Our findings suggest that the epidemiological changes in genetic behaviour between HA‐ and LA‐MRSA are due to the presence of CA‐MRSA confirming that CA‐MRSA has created a public health crisis worldwide.

28 September 2016 in Journal of Microbiology and Biotechnology
Verified
Journal Article
Closed access
HDHesham Dahshan
Hesham Dahshan
AMAbdallah M. A. Merwad
Abdallah M. A. Merwad
TMTaisir Saber Mohamed
Taisir Saber Mohamed
Broiler meat production worldwide has been plagued by lethal food-poisoning bacteria diseases, including listeriosis. A fatality rate of 15.6% was recorded in human beings in the EU in 2015. During 2013, a total of 200 poultry farm samples, including litter, chicken breast, farm feed, and drinking water, were collected to generate baseline data for the characterization of the genus Listeria in broiler poultry farms. Listeria spp. were detected in a total of 95 (47.5%) poultry farm samples. The isolates of Listeria spp. included L. innocua (28.5%), L. ivanovii (12.5%), L. welshimeri (4.5%), and L. monocytogenes and L. seeligeri (1% each). Listeria spp. contamination rates were higher in farm feed (70%), followed by litter (52.5%), chicken breasts (42.2%), and drinking water (10%). Almost all Listeria spp. isolates were resistant to more than three classes of antibiotics (multidrug resistant). Besides this, we observed a significant resistance level to penicillin and fluoroquinolone drugs. However, lower resistance levels were recorded for broad-spectrum cephalosporins. The inlA, inlC, and inlJ virulence genes were detected in almost all of the L. monocytogenes isolates. Thus, food safety management approaches and interventions at all stages of the broiler rearing cycle were needed to control cross-contamination and the zoonotic potential of listeriosis.

4 November 2020 in BMC Veterinary Research
Verified
Journal Article
Open access
PDF file
YTYasmine Hasanine Tartor
Yasmine Hasanine Tartor
WEWafaa M. El-Neshwy
Wafaa M. El-Neshwy
AMAbdallah M. A. Merwad
Abdallah M. A. Merwad
MEMohamed Abo El-Maati
Mohamed Abo El-Maati
RMRehab E. Mohamed
Rehab E. Mohamed
HMHala I. Mahmoud
Hala I. Mahmoud
Background: Dermatophytosis in calves is a major public and veterinary health concern worldwide because of its zoonotic potential and associated economic losses in cattle farms. However, this condition has lacked adequate attention; thus, to develop effective control measures, we determined ringworm prevalence, risk factors, and the direct-sample nested PCR diagnostic indices compared with the conventional methods of dermatophytes identification. Moreover, the phenolic composition of an Aloe vera gel extract (AGE) and its in vitro and in vivo antidermatophytic activity were evaluated and compared with those of antifungal drugs. Results: Of the 760 calves examined, 55.79% (424/760) showed ringworm lesions; 84.91% (360/424) were positive for fungal elements in direct-microscopy, and 79.72% (338/424) were positive in culture. Trichophyton verrucosum was the most frequently identified dermatophyte (90.24%). The risk of dermatophytosis was higher in 4–6-month-old vs. 1-month-old calves (60% vs. 41%), and in summer and winter compared with spring and autumn seasons (66 and 54% vs. 48%). Poor hygienic conditions, intensive breeding systems, animal raising for meat production, parasitic infestation, crossbreeding, and newly purchased animals were statistically significant risk factors for dermatophytosis. One-step PCR targeting the conserved regions of the 18S and 28S genes achieved unequivocal identification of T. verrucosum and T. mentagrophytes in hair samples. Nested-PCR exhibited an excellent performance in all tested diagnostic indices and increased the species-specific detection of dermatophytes by 20% compared with culture. Terbinafine and miconazole were the most active antifungal agents for dermatophytes. Gallic acid, caffeic acid, chlorogenic acid, cinnamic acid, aloe-Emodin, quercetin, and rutin were the major phenolic compounds of AGE, as assessed using high-performance liquid chromatography (HPLC). These compounds increased and synergized the antidermatophytic activity of AGE. The treated groups showed significantly lower clinical scores vs. the control group (P < 0.05). The calves were successfully treated with topical AGE (500 ppm), resulting in clinical and mycological cure within 14–28 days of the experiment; however, the recovery was achieved earlier in the topical miconazole 2% and AGE plus oral terbinafine groups. Conclusions: The nested PCR assay provided a rapid diagnostic tool for dermatophytosis and complemented the conventional methods for initiating targeted treatments for ringworm in calves. The recognized antidermatophytic potential of AGE is an advantageous addition to the therapeutic outcomes of commercial drugs.

1 August 2018 in Vector-Borne and Zoonotic Diseases
Verified
Journal Article
Closed access
RGRasha M.A. Gharieb
Rasha M.A. Gharieb
AMAbdallah M. A. Merwad
Abdallah M. A. Merwad
ASAyman A. Saleh
Ayman A. Saleh
AEAmany M. Abd El-Ghany
Amany M. Abd El-Ghany
Cryptosporidiosis is a parasitic zoonosis implicated in severe diarrhoea in pets and humans. This study aimed to determine the prevalence and genotypes of Cryptosporidium spp. in household dogs and in-contact children, and the risk factors associated with infection in children in Sharkia Province, Egypt. Fecal samples of 100 children (2–12 years old) and 50 dogs (3 months–1 year old) were randomly collected from both rural (children: n = 85, dogs: n = 40) and urban (children: n = 15, dogs: n = 10) households. Initial parasite detection was done by light microscopy, while, genotyping was based on molecular diagnostic assays. The overall prevalence of Cryptosporidium spp. infection in children was 35% using microscopy and 14% using nested polymerase chain reaction (PCR). In dogs, it was 34% using microscopy and 24% using nested PCR. Cryptosporidium spp. from children were identified as distinct genotypes, with the predominance of human genotype I (Cryptosporidium hominis) over the zoonotic genotype II (Cryptosporidium parvum). Moreover, only zoonotic genotype II (C. parvum) was identified in dog samples. The significant risk factors associated with the prevalence of Cryptosporidium infection in children were the presence of diarrheal episodes during time of survey, improper disposal of garbage, and dog feces and contact with other livestock (p ≤ 0.05). This study concluded that the existence of C. parvum in children and dogs residing the same households confirm the zoonotic transmission and its public health significance. Also, the study recommended the necessity of hygienic disposal of dog feces and preventing direct contact of dogs with other livestock.