Salmonella status of table eggs in commercial layer farms in Menoua Division, West region of Cameroon

Cold atmospheric pressure air plasma jet disinfection of table eggs: Inactivation of Salmonella enterica, cuticle integrity and egg quality

Eggshell cuticles are first lines of defense against egg-associated pathogens, such as Salmonella enterica serovar Enteritidis (SE). Infections from eggs contaminated with this strain remain a significant risk. In addition, changes in the cuticle are closely related to changes in egg safety. The emerging non-thermal atmospheric pressure plasma technology enables a high rate of microbial inactivation at near-ambient temperatures, making it ideal for food safety applications. This study examines the effects of a cold atmospheric pressure air plasma jet (CAAP-J) on eggshell cuticle and egg quality whilst inactivating SE. Shell eggs inoculated with SE (7 log10 cfu/egg) were used as the samples to test the decontamination performance of the device. The tests were conducted using an industrial CAAP-J with different power levels (600-800 W), exposure times (60-120 s), at a fixeddistance of 20 mm from the plasma jet and an air flow rate of 3600 L/h. It was found that the best results were obtained after 120 s at maximum plasma power (800 W). Subsequent to the implementation of this plasma procedure, it was determined that no viable cells could be detected. After CAAP-J treatment, the temperature remains below 50.5 °C, thereby minimizing the risk of altering egg quality. All specific measurements (egg white pH, yolk pH, yolk color, HU, and eggshell breaking strength) have shown that CAAP-J treatment has no negative effect on egg quality. No changes in eggshell cuticle quality after CAAP-J treatment was confirmed through scanning electron microscope (SEM).

Inactivating Salmonella Enteritidis on shell eggs by using ozone microbubble water

The major pathogen associated with eggs is Salmonella enterica subsp. enterica serovar Enteritidis (S. Enteritidis) and chlorine washing is the most widely used for sanitization. Microbubble, a novel technique and able to operate in large quantity, has been presented to be an alternative method. Thus, microbubble water combining with ozone (OMB) was applied to disinfect S. Enteritidis spiked on shells at 10⁷ cells per egg. OMB was generated by injecting ozone into a Nikuni microbubble system, then delivered into 10 L of water. After 5, 10, or 20 min of activation time, the eggs were placed into OMB and washed for 30 or 60 s. The controls involved unwashed, water washing, ozone only, and microbubble only (MB). The highest reduction, 5.19 log CFU/egg, was achieved by the combination of 20-min activation and 60-s washing, which was used for following tests of large water quantities. Comparing with the unwashed control, 4.32, 3.73 and 3.07 log CFU/egg reductions were achieved in 25, 80, and 100 L of water, respectively. The other system, Calpeda, with higher motor power was tested in 100 L and obtained a reduction of 4.15 log CFU/egg. The average diameter of bubbles generated by Nikuni and Calpeda pump systems were 29.05 and 36.50 μm, respectively, which both were within the microbubble definition of ISO. Much lower reductions, around 1-2 log₁₀ CFU/egg, were shown with the treatments of ozone only and MB by the same operative parameters. After 15-day storage at ambient temperature, the OMB-treated eggs showed similar sensory quality with the unwashed ones. This is the first study demonstrating that OMB effectively inactivates S. Enteritidis on shell eggs in large quantity of water and does not diminished the sensory characteristics of eggs. Furthermore, bacterial population was under the detection limit in the OMB-treated water.

Use of Phages to Treat Antimicrobial-Resistant Salmonella Infections in Poultry

Simple Summary

Salmonellosis, an infection in humans and animals caused by Salmonella spp., poses a major concern to public health and food safety worldwide. Antibiotics are mostly prescribed to treat salmonellosis. Unfortunately, indiscriminate use of antibiotics leads to the emergence and transmission of multidrug-resistant Salmonella spp. As antibiotics are becoming increasingly ineffective, infections caused by MDR strains will be difficult to manage. The search for an alternative to antibiotics has led scientists to give renewed attention on phage therapy. Though commercial use of phages for controlling Salmonella in poultry is still in its early stage, the use of lytic phages is considered an environmentally friendly, cost-effective, and sustainable antimicrobial approach. Moreover, it provides advantages over antibiotics in terms of specificity, cost of development, resistance, and genetic amenability. Studies on laboratory and field scale use show promise on the effectiveness of phages against MDR Salmonella spp. However, inadequate data on safety of phage use, phage stability, and lack of regulatory framework remain major obstacles in the commercial application of phages. Our article provides a comprehensive overview on global prevalence and antimicrobial resistance of Salmonella in poultry, the efforts to control Salmonella using phage therapy, and challenges as well as future prospects of phage therapy.

Abstract

Salmonellosis is one of the most common bacterial infections that impacts both human health and poultry production. Although antibiotics are usually recommended for treating Salmonella infections, their misuse results in the evolution and spread of multidrug-resistant (MDR) bacteria. To minimize the health and economic burdens associated with antimicrobial resistance, a novel antibacterial strategy that can obliterate pathogens without any adverse effects on humans and animals is urgently required. Therefore, therapeutic supplementation of phages has gained renewed attention because of their unique ability to lyse specific hosts, cost-effective production, environmentally-friendly properties, and other potential advantages over antibiotics. In addition, the safety and efficacy of phage therapy for controlling poultry-associated Salmonella have already been proven through experimental studies. Phages can be applied at every stage of poultry production, processing, and distribution through different modes of application. Despite having a few limitations, the optimized and regulated use of phage cocktails may prove to be an effective option to combat infections caused by MDR pathogens in the post-antibiotic era. This article mainly focuses on the occurrence of salmonellosis in poultry and its reduction with the aid of bacteriophages. We particularly discuss the prevalence of Salmonella infections in poultry and poultry products; review the trends in antibiotic resistance; and summarize the application, challenges, and prospects of phage therapy in the poultry industry.

Cross-Sectional Survey of Prophylactic and Metaphylactic Antimicrobial Use in Layer Poultry Farming in Cameroon: A Quantitative Pilot Study

An evaluation of the patterns of antimicrobial use in livestock can help understand the increasing level of antimicrobial resistance worldwide. This study aimed at evaluating antimicrobial usage in modern layer poultry farms in the West Region of Cameroon. In this light, 70 layer poultry farms and 4 veterinary pharmacies were surveyed. Data on antimicrobial use were collected through interviews using a quantitative-frequency questionnaire and consultation of medical records. The four veterinary pharmacies sold a total of 2.8 tons of antimicrobials (active ingredients) during 2011. At the level of farms, 297 kg of antimicrobials (active ingredients) were used in the 50 layer poultry farms surveyed. Tetracycline, sulfonamides, quinolones, and β-lactams (aminopenicillins) were the most sold and used drugs in layer farms. As for treatment indication, metaphylactic (58.1%) and prophylactic (41.9%) treatments were the most observed practices, and nearly all (99%) treatments were administered per os as remedies to respiratory (33.4%) and digestive (24.7%) tract symptoms. Overall, 78.2% of antimicrobials sold in pharmacies and 67.3% used in the farms belonged to the class of critically important antimicrobials of the WHO categorization of antimicrobials according to their importance to human medicine. Doxycycline, sulfonamide, ampicillin, and streptomycin, which have been banned for layer poultry in the production of eggs for human consumption, were still used in Cameroon. The treatment incidences based on the used daily dose (TI_UDD) and animal daily dose (TI_ADD) were 11.59 and 10.45, respectively. In regard to dosage correctness based on the UDD/ADD ratio, aminoglycosides (100%), macrolides (90.6%), and tetracyclines (74.5%) were the most underdosed, while trimethoprim sulfonamides (45.8%) and β-lactams (35.7%) were overdosed. This study highlights an irrational antimicrobial usage in layer poultry farms. Regulation of the use of antimicrobials and the education of farmers on adequate antimicrobial use are essential to preserve the effectiveness of drugs in both humans and animals.

The application of a novel non-thermal plasma device with double rotary plasma jets for inactivation of Salmonella Enteritidis on shell eggs and its effects on sensory properties

Consumer awareness and distaste towards both bacterial and chemical contaminations on food items have been increasing in recent years. Non-thermal plasma (NTP) is a cutting-edge technology which has been shown to effectively inactivate bacteria on the treated foods. Although the general NTP with a single plasma jet is appropriate for the continuous operation process, it suffers limitations due to its smaller scanning area. Here, a novel NTP device with a double rotary nozzle jet system was utilized, which could treat an area instead of a point. The shell eggs inoculated with Salmonella enterica serotype Enteritidis (SE) were placed on a moving platform under the double rotary nozzle jet system. The efficacy of the NTP treatment on microbial decontamination was evaluated by testing a total of 26 combinations of operating parameters consisting of various plasma power (150, 180, 210 W), argon flow rate (10, 15, 20 slm), repetition of the moving platform (4, 6, 8 times), and speed of the moving platform (5, 10 mm/s). Although significantly higher SE reduction (p < 0.05) was achieved with higher power, more repetitions, larger argon flow rates, and lower speed of the platform, these parameters induced significant alterations in the sensory properties of the treated eggs. By comprehensively considering the bacterial reductions, egg quality, and sensory properties, NTP treatment with combination T (180 W-15 slm-6 times-10 mm/s) was determined to be the optimal parameter, which achieved >4 log CFU/egg of SE reduction and significantly better sensory properties than commercially washed eggs (p < 0.05). Additionally, SEM analysis revealed that NTP treatment with combination T resulted in less damage to egg cuticles compared to commercially washed eggs. This novel NTP device offers an efficient antibacterial activity under shorter exposure time (30 s), smaller argon flow rate (15 slm), and lower power (180 W) without adversely affecting the overall quality of the treated eggs. Therefore, this NTP device equipped with the double rotary jet system possesses a potential solution for future industrial applications.

Prevalence, Serotype, Antibiotic Susceptibility, and Genotype of Salmonella in Eggs From Poultry Farms and Marketplaces in Yangling, Shaanxi Province, China

Poultry products such as eggs provide essential nutrients to the human body and thus play vital roles in the human food network. Salmonella is one of the most notorious foodborne pathogens and has been found to be prevalent in eggs. To better understand the characteristics of Salmonella in eggs, we investigated the prevalence of Salmonella spp. in 814 fresh eggs collected from poultry farms and retail marketplaces in Yangling, Shaanxi Province, China. The serotype, genotype, and antibiotic susceptibilities of 61 Salmonella isolates recovered from the eggs were analyzed. The average detection rate of Salmonella-positive eggs was 5.6%, with 6.6% of the eggs collected from poultry farms and 5.1% from marketplaces. Thirteen serotypes were identified from the 61 isolates, among which Salmonella Typhimurium (24.5%) and Salmonella Indiana (22.9%) were the most prevalent serotypes. Other dominant serotypes included Salmonella Thompson (13.1%) and Salmonella Enteritidis (11.4%), with the remaining nine serotypes detected at low rates (1.6-4.9%). All the Salmonella isolates tested were resistant to sulfisoxazole (100.0%). The majority (77.1%) of the isolates were resistant to nalidixic acid, amoxicillin-clavulanate, and ampicillin, while nearly two-thirds (63.9-68.9%) were resistant to trimethoprim-sulfamethoxazole, kanamycin, tetracyclines, and chloramphenicol. The rate of resistance to ciprofloxacin was 40.1%; the resistance rates to streptomycin, ceftiofur, and ceftriaxone ranged from 21.3 to 26.2%; and those to gentamicin, amikacin, and cefoxitin were relatively low (3.3-16.4%). Forty-nine (80.3%) Salmonella isolates exhibited resistance to multiple antibiotics, 20 (32.8%) of which were resistant to at least 10 antibiotics. Subtyping by pulse-field gel electrophoresis revealed a close genetic relatedness of Salmonella isolates from poultry farms, in striking contrast to the high diversity of the isolates obtained from marketplaces. Isolates of the same serotype always shared identical genotype and antibiotic resistance profiles, even the ones that were recovered from eggs sampled at different locations and times. These findings indicate that diverse Salmonella spp. with high rates of multidrug resistance are prevalent in fresh eggs in the study area. More attention should be paid to egg production, transportation, and storage to prevent foodborne outbreaks caused by Salmonella.