Despite global improvements in public health facilities, bacterial infections remain an important public health problem worldwide [1]. Among the pathogens, Salmonella is considered the most prevalent foodborne pathogen and has long been recognized as an important zoonotic bacterium of economic significance in animals and humans [2]. Salmonella agents that cause infection in humans are more common in poultry than in other animal species [3]. Therefore, poultry products could be one of the potential sources to harbor a diverse microbial community such as Salmonella enterica, the causative agent of salmonellosis [4]. Though there are several contributing factors such as consumption of raw or unsafe food, cross-contamination, poor personal hygiene, etc. for an outbreak of Salmonellosis in humans, the consumption of chicken products (e.g. meat, liver, and eggs) is considered as the primary route of transmission of Salmonella into the human food chain [5]. In poultry-originated food-borne outcomes, Salmonella ranks the highest in all cases linked to food consumption [6]. Salmonella was accounted for 1335 food-borne outbreaks and 36,940 associated illnesses that were reported to Food Disease Outbreak Surveillance System from 1999 to 2008 and poultry products were responsible for a higher percentage of Salmonella outbreaks of infection compared to other food commodities [7].

From the FAO statement, the production of poultry meat and eggs in Bangladesh is growing rapidly over the last 15 years. Poultry meat production has increased from 660 tons in 1990 to 6.2 million metric tons in 2016 and egg production has increased 11,912.4 million over the same period [8]. The growth rate of chicken production in Bangladesh was 5.3% per year and consumption of broiler meat and eggs could grow by 95% and 78% respectively, in 2020 [9]. This growth will be being driven by the increase in market demand [10]. Salmonellosis is important as both a cause of clinical disease in commercial poultry that hindered the development of the poultry industry in Bangladesh and as a source of human food-borne zoonotic diseases [11]. Ignorance of the veterinary medical profession and its extension services, poor people without any knowledge of zoonotic diseases who are in close contact with livestock and their products and unhygienic processing, maintaining, and marketing the livestock and livestock products have made the situation graver in Bangladesh [12]. In poultry farming, the use of antibiotics has enhanced production via effectively controlling infectious disease and promoting the growth of the chickens, allowing the industry to cope with the increased consumer demands and provide safe and affordable products [13]. But the non-judicious use of antibiotics has been attributed to food-borne outbreaks like salmonellosis, where the etiological agents have been identified as resistant clones [14]. The emergence and proliferation of resistant pathogens and the cognate decrease in the efficacy of antibiotic therapy pose a concrete risk to public health and sustainable farming [13]. The spread of such resistant strains among food animals is life-threatening as they are often non-treatable with currently available antimicrobials [15]. So, animal agriculture such as poultry farming and antibiotic usage on the farms are hot debate topics, because overuse may be a contributing factor for the entrance of AMR pathogens and AMR genes into the food chain [15]. The AMR obtained therefrom is acquired through several mechanistic and epidemiological events, including random mutation, plasmid exchange, horizontal gene transfer, and clonal spread of the resistant isolates [16]. Humans can get exposed to antibiotic-resistant bacteria through the consumption of contaminated meat and eggs or direct transmission from colonized animals or manure and litter [11]. Thereby increasing the proportion of single and multiple antibiotic-resistant isolates showing antimicrobials’ resistance by pathogenic bacteria is a universal public health concern throughout the world especially in developing countries [17]. Because of the phenomenon of developing multidrug-resistant Salmonella isolates, the management of Salmonella infection using regular drugs is very difficult [11] Considering the urgency of the above, the survey of Salmonella in food animal production together with surveillance on antimicrobial resistance patterns is very essential [12]. In recent years, the development of MDR among foodborne pathogens, such as Salmonella spp., has been associated with an increase in human mortality, and longtime hospitalization due to therapy failure [11]. So, this study reports the presence of Salmonella including drug resistance pattern against commonly used antibiotics in poultry chicken in Hathazari region of Chattogram, Bangladesh.

Non-typhoidal Salmonella is considered to be the leading cause of food-borne illness which poses a great problem for the poultry industry and human health in both developing and non-developing countries [20]. Salmonellosis remains one of the most frequent food-borne zoonosis constituting a worldwide major public health concern [6]. Currently, at a global level, the main source of infection for humans includes poultry products (meat, liver, eggs) [7].

We found a considerable high frequency (48%) of contamination in poultry samples with Salmonella spp. (Table 1) which is higher than the recent study in the same area where the prevalence is 29% [16]. The occurrence of Salmonella contamination has also been reported from various parts of the world ranging from 17% - 53% [21] [22] [23] [24]. The prevalence difference could be due to differences in experimental location, environmental condition, sample type, hygiene practice, overall management, and surveillance systems. Among the different poultry samples, distribution of Salmonella in Cloacal swab (40%), raw meat 62.5%, raw liver 37.5%, and eggshell 50% are observed. The prevalence of Salmonella contamination of raw meat (62.5%) observed in this study is significantly high which is in agreement with results reported in Belgium, The United Kingdom, Iran, China, Iraq, and the Russian Federation [25]. This significant variation in the prevalence could be due to sampling procedure, sanitation within the slaughterhouse, possible contamination during poultry processing steps (e.g. the amount of cross-contamination of chicken carcasses by contact with intestinal tracts during slaughter or processing). In our result prevalence of Salmonella on eggshells, the surface is significantly higher (50%). The prevalence of Salmonella was reported at 40% in eggshells in a previous study carried out in Pakistan and 6.1% in India [26]. One possible cause of Salmonella contamination in developing countries is repeated use of the same egg-storing trays. Egg-storing trays contamination might be due to chicken fecal material or due to environmental factors [26]. So, possible horizontal transmission of Salmonella into an egg which is likely to be cross-contamination from feces or the cage environment could be happened [27].

Resistance of Salmonella to antimicrobials is an emerging problem in developing and developed countries [28]. The result from the present study demonstrated a high level of resistance to vancomycin (100%), cephalexin (100%) followed by ampicillin (75%), nalidixic acid (58%), chloramphenicol (41%), Doxycycline (50%) and neomycin (50%) shown in Table 3. Ampicillin, doxycycline, nalidixic acid, and several other antibiotics are widely used as animal feed additives due to their low cost and availability [29]. Indeed, increased use of antibiotics in poultry industries for therapeutic, prophylactic, and growth-promoting purposes increases the selective pressure for resistant phenotypes for applied antibiotics [30]. Chloramphenicol is used to treat human salmonellosis, due to its low cost and adequate therapeutic response [31]. Another most widely used drug for salmonellosis treatment is doxycycline belonging to the group tetracycline. In the present study, 41% for chloramphenicol and 50% isolates were resistant to considerably high doxycycline, due to its unwise and continuous utilization in poultry farms. It has increased microbial resistance, consequently reducing the available therapeutic options. The resistance of bacteria to such drugs has increased and represented a substantial cost to public health [32].

Salmonella serotypes with multidrug-resistant phenotypes are a threat to the poultry of Bangladesh [33]. A considerably high proportion of isolates (11/12, 91.67%) (Table 4) was resistant to three or more antibiotics and 11 multidrug profiles were observed (Table 4). According to the study, two isolates (16.67%) were resistant to 3 drugs, four isolates (33.33%) to 4 drugs, 1 isolate (8.33%) were resistant to 5 drugs and 4 isolates (33.33%) were resistant to 7 drugs. The AMP-C-NA-N-CN-DO-VA (4/12) was the most frequently occurred phenotype. These types of antibiotic-resistant for the isolates in this study are also in agreement with different reports in other parts of African and European countries [34]. Ongoing infection with Salmonella organism and use of medication at breeder level could significantly amplify the prevalence of multiple resistant Salmonella in poultry rearing environment in Bangladesh [35]. Transfer of resistance plasmid to other bacteria facilitates multi-drug resistance. This puts the public health at risk for future antibiotic resistant infection.

In this regard, our antibiogram study suggests that chicken could be a source of multidrug-resistant salmonellosis in human. Similar findings on multidrug resistance among Salmonella strains have been reported from Bangladesh and various parts of the world [36]. On the other hand, the third generation fluoroquinolone-class antibiotic ciprofloxacin showed 83.33% sensitivity, a similar finding was reported by Bangladesh [28]. Cephalosporin group ceftazidime and penicillin group amoxicillin, both antibiotics showed 91.67% susceptibility which was in agreement with several studies where the least resistance was found [28] [37]. This could be an important indication for a mass community for choosing the effective antibiotics to treat diseases caused by Salmonella spp.

In the current study, elevated levels of prevalence and increased amount of antibiotic resistance in Salmonella have been detected in broiler chicken. Though the study was on pilot scale, these findings recommended that, in Bangladesh, poultry is a major avenue of multidrug-resistant Salmonella and suggest that it is difficult to achieve successful antimicrobial therapy for human salmonellosis caused by the strain of poultry origin.

Due to fund constraints and COVID-19 pandemic issues, less sample size was taken to conduct this study.

In the present study, the high prevalence and the detection of multidrug resistant strain highlight the poor management system in the poultry farm. Poultry has been reported as a source of nontyphoidal Salmonella which are resistant to clinically relevant antibiotics and remarkably pose a high risk to both animals and humans. Moreover, indiscriminate use of antimicrobials in poultry animals for growth promotion and disease prevention is considered the key driver behind the surge. More attention should be focused on increasing antibiotic surveillance capacity to cope with the spread of emerging resistance and on the alternative therapeutic approaches.

For validating more reliability, this research needs further work with greater sample size.

The authors would like to thank Professor Dr. Seraj Uddin, Department of Microbiology, University of Ghittagong, for his valuable suggestions and advices also thank Dr. Zobaidul Alam, Department of Microbiology, University of Chittagong for providing laboratory facilities.

Supervised and designed the experiment: KNI, MMH;

Performed the lab work: EE, TC;

Wrote the manuscript: EE, KNI;

Data analysis: EE, KNI and SZ. Improved the manuscript: SZ and KNI;

All authors read and approved the final manuscript.

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

Islam, K.N., Eshaa, E., Hassan, M., Chowdhury, T. and Zaman, S.U. (2022) Antibiotic Susceptibility Pattern and Identification of Multidrug Resistant Novel Salmonella Strain in Poultry Chickens of Hathazari Region in Chattogram, Bangladesh. Advances in Microbiology, 12, 53-66. https://doi.org/10.4236/aim.2022.122005