Application of Bacteriophages for Biocontrol of Extensively Drug Resistant Salmonella Serovars Isolated from Poultry Farms

Salmonella is one of the most common foodborne pathogens causing diseases in humans and animals. Increased resistance to antibiotics necessitates the need for an alternative control strategy. This study aimed to screen, isolate and evaluate the bacteriophage characteristics for biocontrol of pathogenic Salmonella serovars. Twelve Salmonella isolates, including different Salmonella enterica serovars, were obtained from different sources of poultry farms. All isolates were screened for antibiotic sensitivity and showed multiple antibiotic resistance. Two lytic bacteriophages, vB_SalSph_WW1, and vB_SalM_WW2, were isolated from the sewage and characterized against Salmonella enterica serovar Enteritidis. Morphological analysis by transmission electron microscopy revealed that the vB_SalSph_WW1 phage belonged to the family Siphoviridae while the vB_SalM_WW2 phage belonged to the family Myoviridae. Both phages showed a broad host range within the Salmonella genus. Phages vB_SalSph_WW1 and vB_SalM_WW2 had a lytic effect on 3 (25%) and 4 (33.3%) of the 12 Salmonella isolates, respectively. The lytic cycle of each phage was determined by a one-step growth curve and both phages had the same short latent period (15 min). WW1 phage gave a burst size of 90 PFU/infected cell, while the vB_SalM_WW2 phage gave a higher burst size of 150 PFU/infected cell. The stability test revealed that vB_SalSph_WW1 and vB_SalM_WW2 phages were stable at pH 4–9 and pH 4–10, respectively. Both Phages exhibited high degrees of thermal tolerance with active titer as high as 42◦C. However, they lost their stability and the titers declined when heated at 50◦C for 30 min. This study revealed that vB_SalSph_WW1 and vB_SalM_WW2 phages have the potency to be used as an alternative strategy to control the infection of Salmonella in poultry farms and to prevent transmission of Salmonella infection to humans and spread of the pathogen into environment

A study on the prevalence of multidrug resistant food poisoning Salmonella spp. in camel meat and offal with a reduction trial using organic acids

Camel meat is an important source of red meat and essential amino acids in Egypt and other Arab countries. This study aimed at investigation of the prevalence of Salmonella spp. in the camel meat and offal (liver, and kidney) retailed in Zagazig city, Egypt. Besides, antibiogram of the recovered Salmonella spp. was screened. In addition, a reduction trial for Salmonella loads in the prepared camel meat ball using organic acids such as acetic and lactic acids or their combination. The obtained results revealed isolation of Salmonella spp., at 20% (12 out of 60 samples). With the highest prevalence in the liver (30%), followed by kidney (20%), and muscle (10%), respectively. Salmonella spp., that were isolated were identified serologically as S. Enteritidis (33.33%), S. Typhimurium (41.66%), S. Virchow (8.33%), and S. Apeyeme (16.66%). The recovered species showed marked multidrug resiatance with the highest resistance against erythromycin, oxacillin, clindamycin, ampicillin, and nalidixic acid. The use of acetic, lactic acids and their combination could significantly reduce Salmonella load in the camel meat samples. In conclusion, the use of organic acids, particularly a combination of acetic and lactic acids (1:1, 2%) is of a particular importance in reducing Salmonella load in the camel meat

Data_Sheet_1_Antibacterial and anti-biofilm activities of probiotic Lactobacillus plantarum against Listeria monocytogenes isolated from milk, chicken and pregnant women.docx

Listeria monocytogenes (L. monocytogenes) is a foodborne pathogen that poses significant risks to public health and food safety. The present study aimed to identify the presence of Listeria spp. in various samples, including pasteurized milk, chicken fillets, and stool samples from pregnant women in Sharkia Governorate, Egypt. Additionally, the study identified the serotypes, virulence-associated genes, antimicrobial resistance patterns, and biofilm formation in L. monocytogenes isolates. Moreover, the antibacterial and anti-biofilm activity of Lactobacillus plantarum ATCC 14917 (L. plantarum) against L. monocytogenes isolates was investigated. A cross-sectional study was conducted from August 2021 to January 2022 to collect 300 samples of pasteurized milk, chicken fillets, and stool from pregnant women admitted to outpatient clinics of hospitals. The results showed that 32.7% of the samples were positive for Listeria spp., including L. innocua (48.9%), L. monocytogenes (26.5%), L. ivanovii (14.3%), L. grayi (5.1%), and L. welshimeri (5.1%). Among all L. monocytogenes isolates, hlyA, actA, inlC, and inlJ virulence-associated genes were detected. However, the virulence genes plcB, iap, and inlA were found in 10 (38.5%), 8 (30.8%), and 25 (96.2%) isolates, respectively. The L. monocytogenes isolates classified into four serotypes (1/2a, 1/2b, 1/2c, and 4b), with 1/2a and 4b each identified in 30.8% of the isolates, while 1/2b and 1/2c were identified in 19.2% of the isolates. All L. monocytogenes isolates showed 100% resistance to streptomycin, kanamycin, and nalidix acid, and 92.3% of isolates showed gentamicin resistance. However, all isolates were susceptible to ampicillin and ampicillin/sulbactam. Multidrug resistance (MDR) was observed in 20 (76.9%) L. monocytogenes isolates. The biofilm formation ability of 26 L. monocytogenes isolates was evaluated at different incubation temperatures. At 4°C, 25°C, and 37°C, 53.8, 69.2, and 80.8% of the isolates, respectively, were biofilm producers. Furthermore, 23.1% were strong biofilm producers at both 4°C and 25°C, while 34.6% were strong biofilm formers at 37°C. Treating L. monocytogenes isolates with L. plantarum cell-free supernatant (CFS) reduced the number of biofilm-producing isolates to 15.4, 42.3, and 53.8% at 4°C, 25°C, and 37°C, respectively. L. plantarum’s CFS antibacterial activity was tested against six virulent, MDR, and biofilm-forming L. monocytogenes isolates. At a concentration of 5 μg/mL of L. plantarum CFS, none of the L. monocytogenes isolates exhibited an inhibition zone. However, an inhibition zone was observed against L. monocytogenes strains isolated from pasteurized milk and pregnant women’s stools when using a concentration of 10 μg/mL. Transmission electron microscopy (TEM) revealed that L. plantarum CFS induced morphological and intracellular structural changes in L. monocytogenes. In conclusion, this study identified virulent MDR L. monocytogenes isolates with strong biofilm-forming abilities in food products in Egypt, posing significant risks to food safety. Monitoring the prevalence and antimicrobial resistance profile of L. monocytogenes in dairy and meat products is crucial to enhance their safety. Although L. plantarum CFS showed potential antibacterial and anti-biofilm effects against L. monocytogenes isolates, further research is needed to explore its full probiotic potential.</p