Antimicrobial Resistance (AMR) has become a big threat to global health. It has risen to dangerously high levels in all parts of the world, making it difficult to treat infectious diseases [1]. This has led to the use of expensive second or third-generation antibiotics and prolonged hospital stay which then translates to higher hospital bills [2]. The high rates of antimicrobial resistance occurrence have attracted the attention of international bodies such as the World Health Organization (WHO), Food and Agriculture Organization (FAO) and, the World Organization for Animal Health who have now forged a united approach to combat it as a common force [1]. It is estimated that worldwide, 700,000 patients die annually as a result of resistant infections and if nothing is done to combat antimicrobial resistance, the death rate is estimated to escalate to 10 million by the year 2050 [3].

Antimicrobials are also used in animals to treat animal diseases and as growth promoters to increase productivity [4]. These animals are important to the well-being of humans as they contribute to human nutrition and wealth especially in countries where the livestock are a major source of income. Any increase in the prevalence of antimicrobial resistance organisms will impact negatively directly and indirectly. To avoid economic loses, livestock farmers are tempted to use more effective and often more expensive antimicrobial in treating sick animals, thus ending-up infringing upon those that are last line options for use in humans; especially if they can easily be bought over the counter [2]. This ends-up in the development of resistance to the few antimicrobials that are relied upon for treating human infections. The microorganisms that are mainly involved in the infection process both in hospital and community are called ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and, Enterobacteriaceae) emphasizing their capacity to “escape” from common antibacterial treatments [5] [6].

The poultry industry is one of the largest and fastest-growing agro structures in Africa and the world. This can be attributed to increasing demand for poultry meat and egg products. These high demands of poultry products have also led to the large-scale accumulation of wastes including manure and litter which may pose disposal and pollution problems to man and the environment. Resistance bacteria of animal origin can be transmitted from animals to humans through the food supply, water or, through direct contact with animals. Sometimes resistant genes can be transferred from animals through human pathogens that are normally human-specific. Contaminated food of animal origin is one source of human bacterial infections when consumed; therefore, the presence of antibiotic-resistant strains in the animal foods such as poultry has raised concerns that the treatment of human infections will be compromised [7] [8]. It has resulted in disease burden, high cost of treatment and, a continuous spread of resistant microbial pathogens [3] [9]. Multiple Antibiotic Resistance (MAR) index is a valid and useful method of tracking especially bacterial infections and drug resistance. MAR index is calculated as the ratio of the number of antibiotics to which an organism is resistant to the total number of antibiotics to which the organism is exposed. Bacteria having MAR index ≥ 0.2 originate from a high-risk source of contamination where several antibiotics are used [10] [11] [12]. Thus, it became imperative to investigate the significance of multi-antibiotic resistant bacteria of poultry source in the emergence and, spread of antibiotic resistance in Enugu metropolis, Nigeria and also evaluate the MAR indices of the isolates.

The limitation of this study was the inability of the authors to collect adequate representative samples for the study. This was due in part to frequent collection of the droppings as manure for their farms by the natives.

The bacteria pathogen isolated were mostly Gram-negative bacteria with E. coli having the highest prevalence. The result is consistent with earlier reports [18] [19]. Although the isolates are part of the enteric flora of the poultry birds, they are of public health importance since they are implicated in antibiotic resistance. Another interesting aspect of this study is the use of the droppings as manure to boost local crops, there is a high possibility of antibiotic resistance gene transfer when the crops are consumed by humans and further transfer between individuals within the community [20]. The variations observed in the carriage of organisms in both poultries may be due to the environmental settings in which the birds are raised, nutrition and, the physiological state of the gut of animals which influence the distribution of organisms found [21].

The Multiple Antibiotic Resistance Index (MARI) as shown on Table 4 is an important analysis to check antibiotic resistance and health risk factors. MAR index is calculated as the ratio of the number of antibiotics to which an organism is resistant to total the number of antibiotics to which the organism is exposed. Bacteria having MAR index ≥ 0.2 originate from a high-risk source of contamination where several antibiotics are used.

Organisms which have MAR indices of greater than ≥0.2 confirm the presence of multidrug-resistant genes originating from the environment where there is an abuse of these drugs and also that the plasmids contain one or more resistance genes, each encoding a single antibiotic resistance phenotype [12] [22]. Using the MARI analysis is also simple and does not require specialized training and expensive equipment [11] [12], while also providing the needed data. Proteus spp is a common cause of community-acquired infection, its prevalence in this study suggests a chance infection spread if its proliferation is not controlled.

MAR index is calculated as the ratio of number of antibiotics to which organism is resistant to total number of antibiotics to which the organism is exposed. Where 1) is the aggregate antibiotic resistance score of all isolates from the sample, 2) is the total number of antibiotics used.

Pseudomonas and Klebsiella pneumoniae are also major pathogens in healthcare-associated infections. They are associated with significant morbidity in humans and are also difficult to manage with first-line antibiotics [23] [24]. The susceptibility test on Table 3, suggests high resistance to the Co-amoxiclav, Ceftazidime, Neomycin and, Amoxicillin. This observation is consistent with previous reports of [15] and [25] whose findings identified multidrug-resistant bacteria in poultry droppings. These organisms have very important implications on human health as antibiotic- resistant infections are difficult to treat and often require expensive antibiotics, long term therapy, and in extreme cases may lead to mortality. Resistance to Gentamicin was significantly high; this is not unexpected because of the use of antibiotics on the bird feeds, particularly through agriculture-influenced and urban-influenced treated and untreated water. Such water samples have all been reported to harbour either bacteria, which carry (multiple) antibiotic-resistance genes, or plasmids carrying these genes [26]. The multidrug-resistance bacteria isolates identified in this study may be due to the indiscriminate use of antimicrobial agents in poultry. The use of these antibiotics for infection control may ultimately favor the widespread of drug-resistant strains in the environment [27].

This study indicates that poultry dung is a carrier of pathogenic bacteria which is capable of transmitting antibiotic resistance genes to human. The most resistant organisms isolated were E. coli and Proteus spp with the latter having the highest frequency. The study calls for close monitoring of antibiotic resistance in our environment and controlled use of antibiotics in poultry since the birds serve as a source of protein and a staple in many homes. The use of the bird droppings for manure is also a call for concern because of the health hazard to the general populace when crops are consumed.

This work received no specific grant from any funding agency.

The authors declare no conflicts of interest regarding the publication of this paper.

Afunwa, R.A., Ezeanyinka, J., Afunwa, E.C., Udeh, A.S., Oli, A.N. and Unachukwu, M. (2020) Multiple Antibiotic Resistant Index of Gram-Negative Bacteria from Bird Droppings in Two Commercial Poultries in Enugu, Nigeria. Open Journal of Medical Microbiology, 10, 171-181. https://doi.org/10.4236/ojmm.2020.104015