The fabrication, characterization, and antibacterial activity of novel nanocomposites based on graphene oxide (GO) nanosheets decorated with silver, titanium dioxide nanoparticles, and zinc oxide nanoflowers were examined. The fabricated nanocomposites were characterized by various techniques including X-ray diffraction, ultraviolet-visible light absorption and fluorescence spectroscopy, Brunauer–Emmett–Teller theory analysis, Fourier transform infrared, and scanning electron microscopy. The antibacterial activity of the GO–metal oxide nanocomposites against two Gram-positive and two Gram-negative bacteria was examined by using the standard counting plate methodology. The results showed that the fabricated nanocomposites on the surface of GO could inhibit the growth of microbial adhered cells, and consequently prevent the process of biofilm formation in food packaging and medical devices. To confirm the antibacterial activity of the examined GO-nanocomposites, we examined their interactions with bovine serum albumin (BSA) and circulating tumor DNA (ctDNA) by steady-state fluorescence spectroscopy. Upon addition of different amounts of fabricated GO-nanocomposites, the fluorescence intensities of the singlet states of BSA and ctDNA were considerably quenched. The higher quenching was observed in the case of GO–Ag–TiO₂@ZnO nanocomposite compared with other control composites.

Enteropathogenic Escherichia coli (EPEC) is a leading cause of diarrhoeagenic diseases in humans and cattle worldwide. The emergence of multidrug-resistant (MDR) EPEC from cattle sources is a public health concern. A total of 240 samples (75 diarrhoeic calves, 150 milk samples, and 15 workers) were examined for prevalence of EPEC in three dairy farms in Egypt. Antimicrobial resistance (AMR) traits were determined by antibiogram and polymerase chain reaction (PCR) detection of β-lactamase-encoding genes, plasmid-mediated quinolone resistance genes, and carbapenemase-encoding genes. The genetic relatedness of the isolates was assessed using repetitive extragenic palindromic sequence-based PCR (REP-PCR). EPEC isolates were detected in 22.7% (17/75) of diarrhoeic calves, 5.3% (8/150) of milk samples, and 20% (3/15) of worker samples. The detected serovars were O26 (5%), O111 (3.3%), O124 (1.6%), O126 (0.8%), and O55 (0.8%). AMR-EPEC (harbouring any AMR gene) was detected in 9.2% of samples. Among isolates, bla_TEM was the most detected gene (39.3%), followed by bla_SHV (32.1%) and bla_CTX-M-1 (25%). The qnrA, qnrB, and qnrS genes were detected in 21.4%, 10.7%, and 7.1% of isolates, respectively. The bla_VIM gene was detected in 14.3% of isolates. All EPEC (100%) isolates were MDR. High resistance rates were reported for ampicillin (100%), tetracycline (89.3%), cefazolin (71%), and ciprofloxacin (64.3%). Three O26 isolates and two O111 isolates showed the highest multiple-antibiotic resistance (MAR) indices (0.85–0.92); these isolates harboured bla_SHV-12 and bla_CTX-M-15 genes, respectively. REP-PCR genotyping showed high genetic diversity of EPEC, although isolates belonging to the same serotype or farm were clustered together. Two worker isolates (O111 and O26) showed high genetic similarity (80–95%) with diarrhoeic calf isolates of matched serotypes/farms. This may highlight potential inter-species transmission within the farm. This study highlights the potential high risk of cattle (especially diarrhoeic calves) as disseminators of MDR-EPEC and/or their AMR genes in the study area. Prohibition of non-prescribed use of antibiotics in dairy farms in Egypt is strongly warranted.

The present study was designed to investigate the presence of genes that conferred resistance to antimicrobials among Enterobacteriaceae that were isolated from diarrhoeic calves. A total of 120 faecal samples were collected from diarrhoeic calves that were raised in Kafr El-Sheikh governorate, Egypt. The samples were screened for Enterobacteriaceae. A total of 149 isolates of bacteria were recovered and identified; Escherichia coli was found to be the most overwhelming species, followed by Citrobacter diversus, Shigella spp., Serratia spp., Providencia spp., Enterobacter spp., Klebsiella pneumoniae, Proteus spp., Klebsiella oxytoca, and Morganella morganii. All isolates were tested for susceptibility to 12 antimicrobials; resistant and intermediately resistant strains were screened by conventional polymerase chain reaction for the presence of antimicrobial resistance genes. Of the 149 isolates, 37 (24.8%) exhibited multidrug resistant phenotypes. The most prevalent multidrug resistant species were E. coli, C. diversus, Serratia spp., K. pneumoniae, Shigella spp., Providencia spp., and K. oxytoca. Class 1 integrons were detected in 28 (18.8%) isolates. All isolates were negative for class 2 integrons. The bla_TEM gene was identified in 37 (24.8%) isolates, whereas no isolates carried the bla_CTX-M gene_. The florfenicol gene (floR) was detected in two bacterial isolates (1.3%). The findings of this study reveal that calves may act as potential reservoirs of multidrug resistant bacteria that can be easily transmitted to humans.

Salmonella spp. are one of the most frequently reported foodborne pathogens worldwide. The present study investigated the virulence genotypes and antimicrobial sensitivity of Salmonella spp. isolated from broiler chickens in Kafr El-Sheikh governorate, Egypt. A total of 180 samples [liver (n=70), spleen (n=70) and caecum (n=40)] collected from 50 different broiler chicken flocks were used to isolate Salmonellae. All suspected samples were examined through a series of conventional bacteriological, biochemical, and serological techniques for isolation and identification of Salmonella spp. All isolates were tested for susceptibility to 16 antimicrobials. Virulence factors were determined using the polymerase chain reaction assays targeting the invA, pefA, avrA, sopB and spvC. The overall isolation percentage of Salmonella was 6.1%. Eleven Salmonella isolates belonging to four different serovars were recovered. S. Belgdam was the most predominant species (7/11, 63.6%), followed by S. Typhimurium (2/11, 18.2%), and S. Virchow and Salmonella enterica subsp. Salamae (S. Salamae) (1/11, 9.1% each). All the isolates were positive for all tested genes except S. Salamae, which harbored neither the sopB nor avrA genes. All isolates exhibited resistance to almost all antimicrobials used. The finding of the present study show high positivity of virulence genes as well as multidrug resistance of all serotypes suggesting pathogenic Salmonella strains. Keywords: Salmonella; Chicken; cPCR; Virulence genes; Antimicrobials.

Bacillus cereus is an important, opportunistic, foodborne pathogen found in various dairy products. In this study, the prevalence, physiological characteristics, antimicrobial resistance profile, and enterotoxigenic genes (ces and hbla) of b. cereus were investigated in isolates from Egyptian dairy products. A total of 150 samples, including soft white cheese, milk powder, and ultra-high temperature (UHT) milk (50 of each), were collected from local dairy stores in EL-Gharbia governorate, Egypt from April 2019 to October 2019. Of these, 29 samples were contaminated with b. cereus (an overall prevalence of 19.3%). Based on cultural, morphological, and biochemical characteristics, 48 isolates were detected including 27 (56.25%) from soft white cheese, 9 (18.75%) from milk powder, and 12 (25%) from UHT milk. Antibiotic susceptibility assessment showed that all isolates exhibited high sensitivity to amikacin, doxycyclin, gentamycin, ciprofloxacin, while significant resistance to kanamycin, clindamycin, nalidixic acid, cephalothin, and sulphamethoxazole was also observed. All isolates were examined for the presence of emetic (ces) and diarrheal (hbla) genes using the PCR method; ces was detected in 12 (25%) isolates, hbla in 14 (29.2%) isolates, while 22 (45.8%) isolates did not harbor either gene. These findings indicate the need for the application of adequate preventive measures and personnel hygiene in dairy processing lines to minimize b. cereus load in final products.

Background: Staphylococcus aureus (S. aureus) is well-recognized worldwide as one of the main etiological agents of mastitis in dairy animals. The current investigation was undertaken to determine the prevalence and virulence factors of S. aureus isolated from camels with clinical mastitis in Egypt. Methods: A total of 200 milk samples were collected from camels suffering from clinical mastitis and they were examined for S. aureus. Both conventional culture-based methods as well as a molecular-based approach were used to identify the bacterium. S. aureus isolates were further examined by polymerase chain reaction (PCR) assay for the presence of seven virulence genes namely, clumping factor A (clfA), alpha-hemolysin (hla), beta-hemolysin (hlb), toxic shock syndrome toxin-1 (tsst-1) staphylococcal enterotoxin A (sea), intercellular adhesion A (icaA) and intercellular adhesion D (icaD). Result: Out of the 200 samples screened, 60 (30%) were confirmed as S. aureus. All S. aureus isolates (100%) were found positive for cIfA, hlb, icaD and tsst-1 genes. The icaA gene was identified in 2 (10%) isolates, sea gene was detected in 3 (15%) isolates whereas, none of the isolates was found positive for the hla gene. The findings of our study reveal a notable prevalence of S. aureus harbouring virulence genes, indicating a crucial role for these factors in the pathogenesis of camel mastitis.