Listeria monocytogenes is an important foodborne pathogen responsible for human listeriosis, which is a disease with high hospitalisation and mortality rates. The bacteria are usually susceptible to most antibacterial substances, but resistance to some of them has been recently observed. The present study introduces the evidence on the emergence of antibiotic resistance among L. monocytogenes strains isolated from food and food-production environments in Poland.

Campylobacteriosis is the most common human foodborne bacterial infection worldwide and is caused by bacteria of the Camplylobacter genus. The main source of these bacteria is poultry, but other food-producing animals such as pigs are also responsible for human infections. An increasing number of strains with resistance to fluoroquinolones and other antimicrobials such as macrolides were recently noted. The aim of the study was to investigate Campylobacter contamination of porcine carcasses and determine the antimicrobial resistance of the obtained isolates.

Emergence of antimicrobial resistance (AMR) among fish bacterial pathogens is one of the major global public threats. Attempts are being made to develop novel alternatives as a promising approach to combat multidrug resistance disease-causing bacteria. Natural antimicrobials such as essential oils (EOs) are a potential unique strategy to treat bacterial infections with a reduced risk of resistance developing. This study aimed to evaluate the antimicrobial activity of some essential oils (EOs) namely, cinnamon (Cinnamomum zeylanicum), clove (Syzygium aromaticum), Peppermint (Mentha piperita) , and black cumin (Nigella sativa) against some fish pathogens implicated with aquaculture disease outbreaks like Aeromonas hydrophilia, Pseudomonas fluorescence, Photobacterium damselae and Streptococcus agalactiae using agar well diffusion assay. We found significant differences on the antibacterial activity depending on the type of essential oils and bacterial strain. Among all the tested EOs, cinnamon essential oil (CEO) was shown to be the most effective with minimum bactericidal concentration (MBC) ranged from 0.0156-0.125 ml/ml. As a result, it was selected for our in vivo investigations. We next aimed to investigate the effects of dietary CEO on growth performance, disease resistance and immune response of fish. A total of 150 striped catfish (Pangasianodon hypophthalmus) were fed with different levels of CEO (0, 1.50, 2.0, 2.50, and 3.0 mL/kg diets) (assigned as control, Diet 1, Diet 2, Diet 3 and Diet 4) for 60 days. Compared to control, fish fed with graded levels of dietary CEO showed significant (P < 0.05) increase in final body weight, weight gain %, and specific growth rate particularly at fish group fed diet 3. Of interest, there were no significant differences (P > 0.05) in feed conversion ratio and survival rates among control and CEO-supplemented groups. Moreover, we found significant (P < 0.05) increases in plasma lysozyme activity and total IgM levels in a dose dependent manner with dietary CEO supplementation. After feeding trials, we investigated their potential to defend striped catfish against A. hydrophila challenge. Fish fed control diet had the highest mortality rates; in contrast, fish fed diets supplemented with CEO had higher levels of resistance to the bacterial infection, with the lowest mortality rates in the fish group fed diet 3. Overall, these findings showed that EOs exhibit a great potential to be used as antimicrobial agents against fish pathogens. Moreover, dietary administration of CEO, particularly at 2.5 ml/kg feed, can be regarded as a promising component for improving growth, immunological responses and potential alternatives to conventional antimicrobials for control of microbial infections in fish.

One of the most costly diseases is avian colibacillosis. Virulence genes determine E. coli pathogenicity. This study was undertaken to explore the existence of some virulence-associated genes and resistant configurations of Escherichia coli recovered from broiler chicks. Thirteen E. coli isolates were exposed to an investigation of antimicrobial susceptibility profile against 17 antimicrobial agents that exhibited the highest resistance found against amoxicillin, florfenicol, penicillin, amoxicillin clavulanate, tetracycline, meropenem, sulfamethoxazole-trimethoprim, and chloramphenicol in the percentage of 100%, 100%,100%, 92.3%, 76.9%, 69.2%, 61.5%, and 61.5%, respectively while the isolates exhibited highest sensitivity found to fosfomycin, imipenem, azetronam and ciprofloxacine in the percentage of 100%,92.3%,76.9% and 69.2%, respectively. Moreover, the thirteen E. coli isolates were exposed to the revealing of some virulence genes (iss, omp-T, hlyF, iroN, iuta, iucD, papC, cva, astA, tsh, and irp2) by polymerase chain reaction (PCR). The results showed that the percentages rates were 84.6, 76.9, 76.9, 76.9, 61.5, 53.8, 38.4, 30.7, 23, 15.3 and 15.3%, respectively. A significant correlation between most antimicrobial-resistant phenotypes and virulence genes in E. coli isolates. Antimicrobial use in chickens should be reasonable to prevent antibiotic-resistant microorganisms, according to our findings.

This study was carried out in Alexandria Province for a period of 12 months from November 2021 to October 2022 in the laboratory of Animal Hygiene and Zoonoses Department, Faculty of Veterinary Medicine, Alexandria University for isolation and molecular identification of Salmonella from some food products of animal origin as well as humans. In addition, the antimicrobial susceptibility testing of the identified bacterial strains was assessed. A total of 450 food samples, comprising chicken paneeh, chicken burger, chicken luncheon, minced meat, beef burger, and kariesh cheese (75 each), were randomly gathered from. In addition, a total of 100 human stool samples have been obtained from 60 diarrheal individuals and 40 apparently healthy ones. Isolation of Salmonella from food samples on XLD clarified that the recovery rate was 12, 8, 5.3, 13.3, 9.3 and 5.3 % for Chicken paneeh, Chicken burger, Chicken luncheon, Minced meat, Beef burger and Kariesh cheese, respectively (40 isolates) while biochemical identification showed that the detection rate was 9.3, 5.3, 5.3, 8, 5.3 and 4% from the same samples, respectively (28 isolates only). Moreover, the molecular identification revealed the detection of 11 isolates only. Finally, the serological identification of 11Salmonella isolates clarified the presence of S. Enteritidis, S. Haifa, S. Inganda, S. Tamale, S. Typhimurium and S. Shangani with various rates. Antimicrobial susceptibility of Salmonella strains (n=11) isolated from food products revealed that Ciprofloxacin was the most effective antibiotic against the tested isolates (90.9 %) followed by Doxycycline (72.73 %) while Cephalexin was the least effective antibiotics as it was noticed that 100% of isolates were resistant. On the other hand, Isolation of Salmonella from the stool samples on XLD (43 isolates) clarified that the recovery rate was 53.3 and 27.5 % for diarrheic and apparently healthy individuals, respectively while biochemical identification tests showed that the detection rate was 25 and 10 % for diarrheic and apparently healthy individuals, respectively (19 isolates only). In addition, the molecular identification of isolates revealed the detection of 16 isolates only. Finally, the serological identification of Salmonella isolates (n=11) recovered from food products clarified the presence of S. Enteritidis, S. Haifa, S. Inganda, S. Typhimurium, S. Montevideo and S. Tsevie with various rates. Finally, antimicrobial susceptibility of Salmonella strains (n=11) isolated from stool samples revealed that Vancomycin and Doxycycline were the most effective antibiotics against the tested isolates (93.75 %) while it was noticed that 100% of isolates were resistant to the remaining antibiotics (Ampicillin, Cefotaxim, Cephalexin, Ciprofloxacin, Penicillin G, Streptomycin and Tetracycline).

This study was conducted to investigate the prevalence, serotypes, and antimicrobial resistance of Salmonella and E. coli isolates recovered from 200 meat and meat products samples (fresh beef, imported frozen meat, imported frozen beef liver, minced beef, beef burger, Egyptian luncheon, kofta and fresh beef sausage), collected randomly from supermarkets and grocery stores at El Fayoum governorate, between September 2019 to July 2020. E. coli was detected in 3% (n= 6/200) and Salmonella in 1.5% (n=3/200) of the total samples, respectively. Salmonella isolates were serotyped as S. Infantis from frozen Brazilian meat, S. Typhimurium from fresh beef sausage and S. Tsevie from fresh minced beef. Serotyping of E. coli showed that E. coli O26:H11, E. coli O91:H21, E. coli O128:H2, and E. coli O124 were isolated from fresh minced beef, frozen beef liver, kofta and beef sausage, respectively. Antimicrobial resistance phenotyping revealed that the isolated Salmonella and E. coli strains were resistant to 60-86.66% and 66.66- 93.33% of the total tested antibiotics, respectively. E. coli strains were positive for blaCTX-M, aadB, Sul1, dfrA, tetA(A), blaSHV, and qnrA, while BlaTEM, BlaCTX-M, qnrA and aadB virulence genes were detected in Salmonella. The antimicrobial resistance genotypic and phenotypic data evaluated in this study would be helpful to estimate the transmission of multilinked antimicrobial resistance genes to human pathogens and the likelihood of consumer exposure to resistant strains.

Staphylococci are the most typical bacteria found in cattle with mastitis, either Staphylococcus aureus or coagulase-negative Staphylococci (CNS). The study’s goal was to determine the prevalence of Staphylococci in bovine mastitis, the antimicrobial profile, and evaluate the concentration of pro-inflammatory interleukins (IL-4, IL-6, IL-10) related to the inflammatory response in clinical mastitis by ELISA. S. aureus (54%) and CNS (19%) were detected in 400 samples of milk from both clinical and subclinical bovine mastitis. The S. aureus isolates revealed higher resistance to ampicillin (100%), followed by amoxicillin-clavulanic acid (98.1%), cefotaxime (88.9%), erythromycin (63.2%), cefuroxime (63%), and tetracycline (61.1%). Furthermore, the CNS isolates showed high resistance against amoxicillin-clavulanic acid (100%), followed by ampicillin (94.7%), cefotaxime (89.5%), erythromycin (79.6%), cefuroxime (89.5%), and tetracycline (73.7%). However, the high susceptibility of S. aureus and CNS was observed to imipenem and ciprofloxacin. Furthermore, Cows with clinical mastitis reported high levels of IL-6 in both their serum and their milk. While they have much lower levels of IL-4 and IL-10 than normal ones (P < 0.001). In conclusion, it is recommended that laboratory results be carefully interpreted to avoid antimicrobial therapy for Staphylococci that is not clinically relevant and to ensure the advisable use of antimicrobials. Also, further study on the application of interleukins as therapeutic agents against bovine mastitis should be considered.

We aimed to systematize and assess scientific information on tetracycline (TET) resistance genes in animals, products, and by-products in the Latin America and the Caribbean (LAC) region. PRISMA guidelines were followed. Only original articles published in peer-reviewed journals were considered. Sixty articles published between 2003 and 2023 met the inclusion criteria. The geographical areas of study were Brazil, Mexico, Chile, and Costa Rica, and, to a lesser extent, Colombia, Bolivia, Cuba, Jamaica, Puerto Rico, and Uruguay. The studies were related to livestock, wild animals, and pets. The most common isolated bacteria were Escherichia coli and Salmonella spp. The tet genes found in higher frequency in the samples or isolates evaluated were tetA, tetB, tetM, tetL, tetK, tetC, tetO, tetD, tetG, tetW, tetS, tetQ, tetE, tetH, tetJ, tetZ, and tetY. Studies evaluating the presence of tet genes in animals in LAC are limited despite TET being antibiotics widely used in animals. It is necessary to establish cross border public policies that allow the constant training of medical and related personnel regarding the responsible use of antibiotics in animals and the effective monitoring of the phenomenon in the region.