1.1 Introduction
Multi-drug resistance refers to the ability of a microorganism, such as bacteria, to resist the effects of multiple antibiotics that are typically effective against it. in the context of Listeria species, this phenomenon occurs when the bacteria develop mechanisms to survive despite exposure to various antimicrobial agents, posing significant challenges for treatment (McLauchlin et al., 2004). The increasing prevalence of multi-drug resistant (MDR) bacteria poses a significant threat to public health, particularly through the food supply chain. Among the various pathogens of concern, Listeria species have emerged as an important cause of foodborne infections, with poultry being a common source of contamination (Swaminathan & Gerner-Smidt, 2007). The rise in antibiotic resistance among foodborne pathogens has been linked to the extensive use of antimicrobials in animal farming, which promotes the selection of resistant strains. Studies have shown that both live and frozen chicken can harbor Listeria species, which can exhibit resistance to multiple antibiotics, complicating treatment and control efforts (Olaimat et al., 2018).
As a prelude to other parts of this study, this chapter will discuss the background upon which this study was initiated, the statement of problems that led to this study, the Aim and Objectives of the study. Others are Significance of the study, Scope of work, Limitation of the study and Definition of terms.
1.2 Background of Study
Historically, multi-drug resistance (MDR) patterns of Listeria species in poultry, particularly in frozen and live chickens, dates back to the increasing use of antibiotics in food production and animal husbandry. Listeria monocytogenes, the most notable species, is a pathogenic bacterium that can cause listeriosis, a serious infection in humans. Over time, as antibiotics were used to prevent infections and promote growth in poultry, some strains of Listeria developed resistance to multiple drugs, making them harder to treat. The issue of MDR in Listeria was first observed in the mid-20th century when researchers noticed that certain bacterial strains were becoming less responsive to traditional antibiotic treatments. Studies in the 1990s highlighted that Listeria isolates from poultry were resistant to drugs such as tetracycline, erythromycin, and penicillin. Since then, the problem has escalated due to the widespread use of antibiotics in poultry farms, coupled with inadequate handling and improper regulation of antibiotics.
Recent studies have shown that Listeria species isolated from frozen and live chickens in various markets exhibit resistance to multiple antibiotics, including ampicillin and trimethoprim-sulfamethoxazole, which were once effective against these bacteria. This resistance is attributed to genetic mutations and the horizontal gene transfer mechanisms within bacterial populations, which allow them to adapt and survive even in the presence of antibiotics. The increasing prevalence of MDR Listeria poses significant public health risks, as infections from resistant strains can lead to higher morbidity and mortality rates, particularly among immuno compromised individuals, pregnant women, and the elderly. The situation calls for stringent antibiotic use regulations in poultry farming and enhanced surveillance systems to monitor resistance patterns in bacterial species such as Listeria.
The global rise in antibiotic-resistant bacteria has created substantial challenges in healthcare and food safety, with multi-drug resistant (MDR) pathogens now prevalent in various sectors of animal husbandry, including poultry farming. Poultry products, such as live and frozen chicken, are known to harbor several bacterial pathogens, including Listeria species. These bacteria, especially Listeria monocytogenes, are capable of causing listeriosis, a serious foodborne illness that primarily affects immuno compromised individuals, pregnant women, newborns, and the elderly (Schlech, 2019). The contamination of poultry with Listeria species can occur at different points in the production chain, from farming practices to the processing and storage of poultry products. The misuse and overuse of antibiotics in poultry farming are widely recognized as significant contributors to the emergence of MDR bacteria (Van Boeckel et al., 2015). In many developing countries, antimicrobials are used not only to treat infections in livestock but also to promote growth and prevent disease. This excessive use creates selective pressure that fosters the development of resistance in bacterial populations, which can then be transferred to humans through the consumption of contaminated food products (Khan et al., 2018).
The presence of antibiotic-resistant Listeria in poultry represents a critical food safety issue, as it complicates the treatment of infections in humans and increases the risk of MDR strains spreading through the food chain. According to Norrung et al., (2017), frozen and live chicken, both of which are widely consumed, can serve as significant vehicles for the transmission of Listeria species. Frozen poultry, despite undergoing freezing processes, can still harbor viable Listeria, as these bacteria are capable of surviving low temperatures for extended periods (Norrung et al., 2017). Live chickens, on the other hand, may acquire Listeria from their environment, including contaminated feed, water, and unsanitary housing conditions. The persistence of MDR Listeria in both live and frozen poultry products has important public health implications, particularly in regions where antibiotic regulations are lax and where proper food handling and storage practices may not be strictly enforced.
Therefore, in Nigeria where the research was carried out, the activities that was conducted is to know the multi drug resistance patterns of listeria species in frozen and live chicken sold.
1.3 Statement of Problems
Investigation revealed that the one of the critical problems is the overuse and misuse of antibiotics in poultry farming, which is driving the emergence of drug-resistant Listeria species. The lack of proper regulation in the use of antibiotics is contributing to the development of resistance, making once-effective treatments less reliable. Additionally, inadequate monitoring and control measures in the food supply chain are allowing contaminated poultry products to reach consumers, further exacerbating the risk of infection from resistant strains.
Furthermore, the MDR problem also raises issues related to the effectiveness of public health interventions. The resistance of Listeria to commonly used antibiotics is reducing the effectiveness of current treatment regimens, increasing the potential for outbreaks and severe health outcomes. Research indicates that the development of MDR in Listeria is not only a local but also a global concern, as international trade in poultry products means that resistant strains can spread across borders (Kathariou, 2002). It is against the backdrop that this study seeks to address these problems by evaluating the multi drug resistance patterns of listeria species in frozen and live chicken sold.
1.4 Aim and Objectives of Study
The aim of the study is to investigate the multi-drug resistance (MDR) patterns of Listeria species isolated from frozen and live chickens sold in markets. In achieving this aim, the following specific objectives were laid out as follows:
- To identify the presence of Listeria species in frozen and live chickens sold in selected markets.
- To determine the antibiotic resistance profiles of the Listeria isolates.
- To evaluate the prevalence of multi-drug resistant Listeria species in the poultry samples.
- To assess the potential health risks associated with the consumption of chicken contaminated with MDR Listeria.
- To recommend strategies for controlling the spread of MDR Listeria in the poultry supply chain through improved food safety practices.
1.5 Research Questions
The study came up with research questions so as to be able to ascertain the above stated objectives. The specific research questions for the study are stated below as follows:
- What is the prevalence of Listeria species in frozen and live chickens sold in selected markets?
- Which Listeria species are most commonly identified in the poultry samples?
- What are the specific antibiotic resistance patterns exhibited by the Listeria isolates?
- How many of the Listeria isolates demonstrate multi-drug resistance?
- What factors contribute to the emergence of multi-drug resistant Listeria species in frozen and live chicken?
- What potential health risks do multi-drug resistant Listeria species pose to consumers?
- What food safety practices can be implemented to reduce the risk of MDR Listeria contamination in poultry?
1.6 Research Hypothesis
In order to pursue the objective of this study, the following generalized statements have been designed to guide and aids in obtaining the result for the experiment to be conducted. For this work, the null hypothesis will be represented with H0 while the alternative hypothesis will be represented with hypothesis H1.
- H01: There is no significant difference in the prevalence of multi-drug resistant Listeria species between frozen and live chickens sold in markets.
- H02: Multi-drug resistant Listeria species are prevalent in frozen and live chickens sold in markets, and their presence is associated with the antibiotic use practices in poultry farming.
1.7 Significance of Study
The significance of this study will extend to various stakeholders involved in food safety and public health.
- For policymakers, the findings will provide evidence-based insights that will guide the formulation of regulations regarding antibiotic use in poultry farming. This will help create policies aimed at reducing the prevalence of multi-drug resistant Listeria and improving overall food safety standards.
- For public health officials, this research will highlight the health risks associated with multi-drug resistant Listeria species, allowing for targeted public health campaigns and intervention strategies. This will enhance efforts to mitigate the impact of foodborne illnesses caused by resistant strains.
- For poultry farmers, the study will emphasize the importance of responsible antibiotic use and promote best practices in animal husbandry. This will support sustainable farming practices that can reduce the emergence of drug-resistant bacteria and ensure healthier livestock.
- For food safety regulators, the research will provide critical data to improve monitoring and surveillance systems for Listeria in the poultry supply chain. This will enable more effective inspections and quality control measures to prevent contaminated products from reaching consumers.
- For consumers, the study will raise awareness about the potential dangers of multi-drug resistant Listeria in poultry products. This will encourage safer food handling practices and informed purchasing decisions, ultimately promoting better public health outcomes.
1.8 Scope of the Study
The scope of the research is focused on the multi drug resistance patterns of listeria species in frozen and live chicken sold.
1.9 Limitations of the Study
During the course of this study, many things militated against its completion, some of which are:
- The study did not account for environmental factors or farming practices that could influence the presence of multi-drug resistant Listeria in poultry. Factors such as the use of antibiotics in feed and water, biosecurity measures, and overall farm management practices were not explored in detail, which could have provided valuable context for the findings.
- Furthermore, the study was conducted within a specific timeframe, and the dynamics of antibiotic resistance patterns are constantly changing. Therefore, the findings may not fully capture the evolving nature of multi-drug resistance in Listeria species, necessitating further research to monitor trends over time.
1.10 Definition of Terms
Multi-Drug Resistance (MDR): Multi-drug resistance refers to the ability of a microorganism, such as bacteria, to resist the effects of multiple antibiotics that are typically effective against it. in the context of Listeria species, this phenomenon occurs when the bacteria develop mechanisms to survive despite exposure to various antimicrobial agents, posing significant challenges for treatment (McLauchlin et al., 2004).
Listeria Species: The term "Listeria species" primarily refers to a group of bacteria, including Listeria monocytogenes, which is known to cause listeriosis, a serious infection in humans, particularly in vulnerable populations. Other species in the genus Listeria include Listeria innocua, Listeria welshimeri, and Listeria ivanovii, which are generally less pathogenic (Nicolas et al., 2011).
Frozen Chicken: Frozen chicken refers to poultry meat that has been preserved at low temperatures to inhibit the growth of bacteria and prolong shelf life. This form of chicken is commonly sold in markets and can harbor pathogens if not handled or cooked properly, making it essential to monitor for contaminants like Listeria (Zhang et al., 2019).
Live Chicken: Live chicken refers to poultry that is sold in its unprocessed state, alive and not yet prepared for consumption. This category includes birds sold at markets for immediate slaughter and processing. The handling and transportation of live chickens raise concerns about the transmission of pathogens, including multi-drug resistant strains of Listeria (Buchanan et al., 2017).
Antibiotic Resistance: Antibiotic resistance is the ability of bacteria to survive and multiply despite the presence of antibiotics designed to kill or inhibit them. This resistance can arise through genetic mutations or the acquisition of resistance genes from other bacteria. In poultry, the overuse of antibiotics has contributed significantly to the emergence of resistant strains, including Listeria (Bengtsson & Greko, 2014).
