Salmonella enterica is one of the most common causes of foodborne illness worldwide. Contaminated poultry products, especially meat and eggs are the main sources of human salmonellosis. Thus, the aim of the present study was to determine prevalence, antimicrobial resistance profiles, virulence, and resistance genes of Salmonella Enteritidis (S. enteritidis) and Salmonella Typhimurium (S. Typhimurium) isolated from laying hens, table eggs, and humans, in Sharkia Governorate, Egypt. The antimicrobial activity of Biosynthesized Silver Nanoparticles (AgNPs) was also evaluated. Salmonella spp. were found in 19.3% of tested samples with laying hens having the highest isolation rate (33.1%). S. Enteritidis) (5.8%), and S. Typhimurium (2.8%) were the dominant serotypes. All isolates were ampicillin resistant (100%); however, none of the isolates were meropenem resistant. Multidrug-resistant (MDR) was detected in 83.8% of the isolates with a multiple antibiotic resistance index of 0.21 to 0.57. Most isolates (81.1%) had at least three virulence genes (sopB, stn, and hilA) and none of the isolates harbored the pefA gene; four resistance genes (blaTEM, tetA, nfsA, and nfsB) were detected in 56.8% of the examined isolates. The AgNPs biosynthesized by Aspergillus niveus exhibit an absorption peak at 420 nm with an average size of 27 nm. AgNPs had a minimum inhibitory concentration of 5 µg/mL against S. enteritidis and S. typhimurium isolates and a minimum bactericidal concentration of 6 and 8 µg/mL against S. enteritidis and S. typhimurium isolates, respectively. The bacterial growth and gene expression of S. enteritidis and S. typhimurium isolates treated with AgNPs were gradually decreased as storage time was increased. In conclusion, this study indicates that S. enteritidis and S. typhimurium isolated from laying hens, table eggs, and humans exhibits resistance to multiple antimicrobial classes. The biosynthesized AgNPs showed potential antimicrobial activity against MDR S. enteritidis and S. typhimurium isolates. However, studies to assess the antimicrobial effectiveness of the biosynthesized AgNPs in laying hen farms are warranted.

Cryptosporidium is a protozoan that causes acute gastroenteritis, abdominal pain, and diarrhea in many vertebrate species, including humans, animals and birds. A number of studies have reported the occurrence of Cryptosporidium in domestic pigeons. Thus, this study aimed to identify Cryptosporidium spp. in samples collected from domestic pigeons, pigeon fanciers, and drinking water, as well as to investigate the antiprotozoal activity of biosynthesized silver nanoparticles (AgNPs) on the viability of isolated Cryptosporidium parvum (C. parvum). Samples were collected from domestic pigeons (n = 150), pigeon fanciers (n = 50), and drinking water (n = 50) and examined for the presence of Cryptosporidium spp. using microscopic and molecular techniques. The antiprotozoal activity of AgNPs was then assessed both in vitro and in vivo. Cryptosporidium spp. was identified in 16.4% of all examined samples, with C. parvum identified in 5.6%. The highest frequency of isolation was from domestic pigeon, rather than from pigeon fanciers or drinking water. In domestic pigeons, there was a significant association between Cryptosporidium spp. positivity and pigeon's age, droppings consistency, housing, hygienic and heath conditions. However, Cryptosporidium spp. positivity was only significantly associated with pigeon fanciers' gender and heath condition. The viability of C. parvum oocysts was reduced using AgNPs at various concentrations and storage times in a descending manner. In an in vitro study, the highest reduction in C. parvum count was observed at the AgNPs concentration of 1000 µg/mL after a 24 h contact time, followed by the AgNPs concentration of 500 µg/mL after a 24 h contact time. However, after a 48 h contact time, a complete reduction was observed at both 1000 and 500 µg/mL concentrations. Overall, the count and viability of C. parvum decreased with increasing the AgNPs concentration and contact times in both the in vitro and in vivo studies. Furthermore, the C. parvum oocyst destruction was time-dependent and increased with increasing the contact time at various AgNPs concentrations.

Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic bacterium that is widely distributed in aquatic environments and causes major economic losses in fish and public health hazards.This study aimed to identify the occurrence of P. aeruginosa in samples collected from fish and fish handlers, and to investigate the antimicrobial susceptibility, virulence determinants, and biofilm genes of P. aeruginosa isolates. A total of 276 samples were cross-sectionally collected from Nile tilapia (53), Golden grey mullet (52), Mediterranean horse mackerel (50), Striped red mullet (71), and fish handlers (50) at five different retail fish markets in Damietta Governorate, Egypt. Pseudomonas species (spp.) were biochemically identified in 57.9% of the total examined samples. Peudomonas aeruginosa were the most prevalent species isolated from the fish and human samples via PCR technique. Peudomonas aeruginosa isolates exhibited full resistance (100%) to tobramycin (TOB), gentamicin (CN), and colistin (CL), with a high level of susceptibility (88.5%) to imipenem (IPM) using the disk diffusion method. Most P. aeruginosa isolates (84.6%) exhibited drug resistance, with 61.5% were multidrug resistance (MDR) and 23.1% were extensive drug resistance (XDR). Most isolates had at least four virulence-associated genes (lasB, toxA, exoU, and oprL) and three biofilm genes (psIA, peIA, and lasR) by using uniplex PCR. The lasI, and rhlR Quorum Sensing (QS) genes were identified in 84.6% and 61.5% in the examined P. aeruginosa isolates, respectively. The highest mortality rate in Nile tilapia experimentally infected with P. aeruginosa isolate encoding most of virulent genes. Multivariate analyses revealed high heterogeneity among the examined isolates. This study revealed the emergence of virulent and drug resistant P. aeruginosa isolates in fish, poses high risks to consumers and food. Thus, strict hygienic measures should be considered when catching, handling, and storing fish, in addition to the routine application of antimicrobial susceptibility testing.

Introduction: Candida albicans (C. albicans) can form biofilms; a critical virulence factor that provides effective protection from commercial antifungals and contributes to public health issues. The development of new antifungal therapies, particularly those targeting biofilms, is imperative. Thus, this study was conducted to investigate the antifungal and antibiofilm effects of Lactobacillus salivarius (L. salivarius), zinc nanoparticles (ZnNPs) and nanocomposites (ZnNCs) on C. albicans isolates from Nile tilapia, fish wash water and human fish sellers in Sharkia Governorate, Egypt.Methods: A cross-sectional study collected 300 samples from tilapia, fish wash water, and fish sellers (100 each). Probiotic L. salivarius was immobilized with ZnNPs to synthesize ZnNCs. The study assessed the antifungal and antibiofilm activities of ZnNPs, L. salivarius, and ZnNCs compared to amphotericin (AMB).Results: Candida spp. were detected in 38 samples, which included C. albicans (42.1%), C. glabrata (26.3%), C. krusei (21.1%), and C. parapsilosis (10.5%). A total of 62.5% of the isolates were resistant to at least one antifungal agent, with the highest resistance to nystatin (62.5%). However, 75% of the isolates were highly susceptible to AMB. All C. albicans isolates exhibited biofilm-forming capabilities, with 4 (25%) isolates showing strong biofilm formation. At least one virulence-associated gene (RAS1, HWP1, ALS3, or SAP4) was identified among the C. albicans isolates. Probiotics L. salivarius, ZnNPs, and ZnNCs displayed antibiofilm and antifungal effects against C. albicans, with ZnNCs showing significantly higher inhibitory activity. ZnNCs, with a minimum inhibitory concentration (MIC) of 10 µg/mL, completely reduced C. albicans biofilm gene expression. Additionally, scanning electron microscopy images of C. albicans biofilms treated with ZnNCs revealed asymmetric, wrinkled surfaces, cell deformations, and reduced cell numbers.Conclusion: This study identified virulent, resistant C. albicans isolates with strong biofilm-forming abilities in tilapia, water, and humans, that pose significant risks to public health and food safety.

Introduction: Esherishia coli ( E. coli ) and Salmonella species (spp.) pose serious public health threats because of their ability to contaminate poultry products and spread through farm environments. This study assessed the prevalence, antimicrobial resistance, and virulence gene profiles of E. coli and Salmonella spp. Methods: A cross-sectional study was conducted, involving the random collection of 400 samples from broilers, drinker’s water, feedstuff, broiler litter, and poultry workers in broiler farms. Furthermore, a structural questionnaire was administered to poultry workers to identify potential risk factors and assess the public health implications associated with pathogen transmission. The antimicrobial and anti-virulence activities of melanin against E. coli and Salmonella enteritidis ( S. enteritidis ) were also assessed. Results: E. coli and Salmonella spp. were frequently isolated from broiler farms, with a predominance of. E. coli serotype O111:H2 (25.64%) and S. enteritidis strains (30.4%) among the total examined samples. Multivariate analysis revealed that poultry workers, who had symptoms worsened after starting farm work and those did not use of personal protective equipment (PPE) were strongly associated with E. coli positivity. E. coli isolates exhibited full resistance to ampicillin (AMP) and tetracycline (TET), whereas Salmonella spp. isolates showed full resistance to AMP. Most of the examined E. coli isolates (71.8%) and the Salmonella spp. isolates (60.9%) were multidrug resistant (MDR) strains. In addition, 28.2% of E. coli isolates and 30.4% of Salmonella spp. isolates were -XDR. The stx 1, stx 2, and hyl A virulence genes were respectively detected in 69.2%, 69.2%, and 74.4% of the examined E. coli isolates, whereas the sop B and hil A virulence genes were identified in all Salmonella spp. isolates. One-way repeated-measures analysis of variance (ANOVA) showed that natural melanin treatment significantly reduced the expression of virulence genes in both E. coli and S. enteritidis isolates. Conclusion: The predominance of E. coli serotypes O111 and S. enteritidis highlights the need for improved hygiene practices and zoonotic diseases awareness to limit pathogen transmission in poultry farms. The detection of MDR and XDR strains e emphasizes the consequences of antimicrobial misuse and its implications for public health. Melanin has potential antimicrobial and anti-virulence activities against E. coli and S. enteritidis .