Background and aim: Hamburger is one of the foods that is made of beef or sheep meat and has its own nutritional value. However, this food item may carry many pathogenic microorganisms and on this basis the purpose of this study is to investigate the amount of Escherichia coli in traditional hamburgers of Qom city and the antibiotic resistance of isolates to imipenem and penicillin.
Materials and Methods: In this study, we randomly isolated 80 cases of traditional hamburgers from the supply centers of this product in Qom city and transferred them to the veterinary health laboratory in Qom city on ice, and isolated Escherichia coli and investigated the antibiotic resistance of the isolates.
Results: In this study, out of a total of 80 traditional hamburger samples, 20 cases were infected with Escherichia coli and the highest resistance of the isolates was related to gentamicin with 10% and tetracycline with 15%, respectively.
Conclusion: Considering that Escherichia coli has dangerous strains such as O157H7 and the most consumers of hamburgers are children and teenagers, so it is necessary that the health control of raw materials and tools be evaluated more by regulatory institutions.

Background and aim: Bacterial infections are one of the important causes of casualties and financial losses in the poultry industry. Despite the key role of antibiotics in the treatment of these infectious diseases, a significant increase in antibiotic resistance is considered a threat to societies. Several studies have investigated the antibiotic resistance levels of the different pathogenic bacterial strains in poultry. This study aimed to investigate the bacterial causes of death in chicken farms in Kazeroun City and also to evaluate the drug sensitivity of these bacterial strains.
Materials and Methods: The samples were obtained from the clinically-affected broiler chickens from 118 industrial poultry farms around Kazeroun City during 2021-2022. The samples were cultured on MacConkey agar and eosin methylene blue (EMB) agar culture media. Then, the antibiotic sensitivity of the samples that were positive for Escherichia coli was evaluated by different antibiotics (enrofloxacin, erythromycin, oxytetracycline, tylosin, gentamicin, doxycycline, danofloxacin, difloxacin, sultrim, florfenicol, flumequine, fosbac, chlortetracycline, colistin, lincospectin, and neomycin).
Results: Among the 118 samples, 106 samples were positive for gram-negative bacteria. 100 of the 106 gram-negative samples were positive for Escherichia coli. All the Escherichia coli-positive samples were resistant to neomycin, chlortetracycline, flumoquine, gentamicin, and tylosin. Also, 99% and 97% of the Escherichia coli-positive samples were resistant to lincospectin and difloxacin, respectively. The highest antibiotic sensitivity of the samples was found to fosbac (94%) and Colistin (90%).
Conclusion: Due to the increase in resistance against common antibiotics, alternative methods are needed to slower drug resistance development and also reduce their resulting mortality. Biosecurity and using acidifiers and probiotics are among the ways to reduce bacterial infections and their need for antibiotic consumption.

Background and aim: Listeria monocytogenes is an opportunistic human pathogen that affects food of animal origin and mainly immunocompromised people, the elderly, infants and pregnant women. The purpose of this study was to investigate the prevalence and antibiotic resistance of Listeria monocytogenes isolated from goat and sheep meat sold in Tehran city.
Materials and Methods: 50 samples of goat and sheep meat were randomly isolated from supply centers in Tehran and transferred to the veterinary laboratory of Tehran University in the fall of 2023. Sampling was also done with swap in tools and equipment used in supply centers.
Results: The results showed that out of a total of 25 samples of goat meat and 25 samples of sheep meat, 4 samples (16%) of sheep meat and 8 samples (32%) of goat meat were infected with Listeria monocytogenes. There was a statistically significant relationship between the amount of coliform contamination in goat and sheep meat (p<0.05). The results of antibiotic resistance showed that the highest level of resistance was related to sulfamethoxazole and amoxiclav. Also, the highest and lowest level of contamination was in the refrigerator (50%) and knife (10%).
Conclusion: The high level of contamination and high antibiotic resistance for Listeria monocytogenes isolates indicates the poor health status in the meat product supply centers in Tehran, and it is necessary for the quality centers to make more efforts to establish strict regulations. Also, in case of gastroenteritis caused by Listeria monocytogenes, the use of antibiotics should be limited.

Since the discovery of antibiotics, they have been used widely for disease control. Antibiotics were also found to be useful in growth promotion in the poultry industry. However, their overuse and misuse have led to bacterial resistance against them. Antibiotic resistance is a global issue that results in considerable health and economic losses. Marked antibiotic resistance against various antibiotics has been observed in poultry infections. To counteract the burdens of antibiotic resistance, various alternatives for antibiotics are being studied. These alternative approaches have also been subjects of interest in the poultry industry, as poultry infections result in dramatic economic loss, and in cases of zoonotic infections, the transmission of infection from chicken leads to dramatic health burdens in humans. Phage therapy, probiotics, and anti-microbial peptides administration are some examples of these alternative approaches. Another antibiotic alternative approach is called "enzybiotics". In enzybiotics, peptidoglycan hydrolases (endolysins) are used to degrade bacterial cell walls. These enzymes are mostly found in bacteriophages’ genomes because bacteriophages have to degrade the peptidoglycan layers of bacteria both to enter and exit their bacterial host. Bacterial genomes also contain some regions with peptidoglycan hydrolase properties which help bacteria in growth and division. The properties of various peptidoglycan hydrolases have been studied to find the more potent and applicable ones for future uses. Due to their advantages, endolysins are promising antibiotic alternatives. In this review, we will discuss the role of enzybiotics in the poultry industry. Also, endolysin advantages and limitations of their administration are discussed here.

Background and aim: Mastitis is the most costly disease threatening the cow breeding industry. Early diagnosis of clinical mastitis cases is the best option to prevent cows from getting mastitis. The aim of the present study was to investigate the prevalence and determine the antibiotic resistance pattern of bacterial agents causing subclinical mastitis in dairy cows of Masal.
Materials and Methods: In total, 100 samples of raw milk were collected from cow farms in Masal city. The samples were evaluated and scored using the California mastitis test. The positive samples collected in each milking session were transferred to the laboratory at the frozen condition and microbial culture and antibiogram were performed on them. All data were statistically analyzed using SPSS software version 25.
Results: Results showed that the prevalence of subclinical mastitis was about 67%. The distribution of the most common bacteria isolated from milk samples included: Staphylococcus aureus with 26.9%, Escherichia coli with 16.4%, coagulase-negative Staphylococcus with 10.4%, Streptococcus agalactiae with 10.4%, Streptococcus dysgalactiae with 9% and Enterobacter with 7.5%. Also, 71.4% of coagulase-negative Staphylococcus isolates and 66.7% of Staphylococcus aureus isolates were resistant to penicillin.
Conclusion: In general, all bacterial agents isolated from the studied samples were sensitive to ciprofloxacin. Totally, milk produced from cows with subclinical mastitis transmits antibiotic-resistant microbes to humans and leads to the spread of antibiotic-resistant microbes in humans. Therefore, the prevention and treatment of subclinical mastitis in cows needs more attention.