Overall, 426 samples consisting of chicken small intestine contents (n = 200), cage swabs (n = 149) and wastewater (n = 77) were collected from 40 broiler chicken farms. The overall prevalence of
Escherichia coli from all sources was 60.6% (n = 264) out of which 58.3% (n = 154) were obtained from chickens and 41.7% (n=110) from poultry environments. Out of a total of 110,
Escherichia coli isolates from poultry environments, 60.9% (n = 67) were from cage swabs and 39.1% (n = 43) from wastewater. The sample that has high prevalence of Escherichia coli was chicken small intestine contents.
The results of the antimicrobial susceptibility test against
Escherichia coli showed that there was high resistance to enrofloxacin (87.1%), erythromycin (78.8%), ampicillin (75%), nalidixid acid (67.8%) and tetracycline (62.1%). To a lesser extent,
Escherichia coli was resistant to streptomycin (58.7%), ciprofloxacin (42.1%) and gentamycin (41.3%). Very low resistance rates were seen with the antibiotics aztreonam (14.4%) and amoxicillin-clavulanate (7.2%) (Table 1).
Of 264
Eserichia coli isolates, 78.4% (n = 207) were multidrug resistant (MDR). Out of these, 60.9% (n = 126) were chicken isolates, while 39.1% (n = 81) were poultry environmental isolates. Out of a total of 81,
Escherichia coli isolates from poultry environments, 70.4% (n = 57) were from cage swabs and 29.6% (n = 24) from wastewater.
Of the 264
Escherichia coli isolates, 19.3% (n = 51) were confirmed ESBL producers by phenotypic characterization (Fig 1). The prevalence of ESBL producing
Escherichia coli from chickens was 58.8% (n = 30), while from poultry environments it was 41.2% (n = 21).
Based on the research results, seven types of multidrug resistance patterns were obtained in ESBL-producing
Escherichia coli. The combination “FQ-AM-M-TE-BL” was the most frequent at 41.2%, followed by the combination “FQ-AM-M-BL” at 23.5%. The results showed that the majority of ESBL-producing
Escherichia coli had multidrug resistance to 5 antimicrobial classes (AMC) as much as 41.2% (21/51), the remainder had multidrug resistance to 4 AMC as much as 39.2% (20/51) and 3 AMC as much as 19.6% (10/51), can be seen in Table 2.
The results showed that
Escherichia coli had high resistance to enrofloxacin (87.1%), erythromycin (78.8%), ampicillin (75%), nalidixic acid (67.8%) and tetracycline (62.1%). These results are the same as the results of other studies, from different regions in Indonesia, which showed that
Escherichia coli from broilers in Sukabumi had high resistance to enrofloxacin (72%), ampicillin (100%), nalidixid acid (100%), erythromycin (92 %) and tetracycline (88%)
(Hardiati et al., 2021). The high resistance to enrofloxacin, ampicillin, erythromycin and tetracyclin is clearly related to the high use of these antibiotics in the poultry farming sector in Indonesia
(Efendi et al., 2022). The use of enrofloxacin is the most popular used in poultry in Indonesia at around 60%, followed in sequence by tetracycline, erythromycin and ampicillin
(Grabowski et al., 2022).
This research shows that there are 19.5% ESBL-producing
Escherichia coli (30/154) in isolates originating from chickens. This incidence is slightly lower than previous research in Indonesia which stated that there were 28.75% ESBL-producing
Escherichia coli in broilers in the Blitar area
(Wibisono et al., 2021). The prevalence in this study is much lower compared to the incidence in several other Asian countries, Thailand at 70.5%
(Tansawai et al., 2018), India 87%
(Brower et al., 2017), dan Philippines at 60,26%
(Gundran et al., 2019). The low incidence could be because in Indonesia there is a ban on the use of antibiotic growth promoters (AGP) in the livestock sector which became effective in January 2018 referring to Minister of Agriculture Regulation No. 14/2017. In the past, almost all feed factories added antibiotics as feed additives to commercial feed, this is what caused the high incidence of antibiotic resistance in chicken farms (
Chattopadhyay, 2014). However, the discovery of ESBL-producing
Escherichia coli in chickens is a cause for concern considering that it can attack humans through contaminated chicken carcasses and can spread to the environment surrounding the poultry (
Da Silva et al., 2023).
The phenotypic prevalence of ESBL-producing
Escherichia coli was 19.3%. The prevalence of ESBL producing
Escherichia coli from chickens was 58.8% (n = 30), while from poultry environments it was 41.2% (n = 21). In this study, ESBL-producing
Escherichia coli was not only found in chickens but also in the environment around the cage (cage swabs and wastewater), this proves that there is a spread of ESBL-producing
Escherichia coli from chickens to the surrounding environment. This incident is strengthened by the fact that ESBL-producing
Escherichia coli from chickens has the same multidrug resistance pattern as ESBL-producing
Escherichia coli from cage swabs and wastewater
(Patricio et al., 2022). The “FQ–AM-M-TE-BL” pattern is the most common in chickens as well as in cage swabs and wastewater.
The research results of
Kwoji et al., (2019) shows that the transfer of resistance genes in
Escherichia coli is quite high in the poultry farming environment. Poultry farming environments often have a high concentration of microorganisms, thus triggering the creation of poor environmental quality and benefiting the spread of ESBL-producing
Escherichia coli because the ESBL coding gene in the plasmid can be transferred to other bacteria
(Yanestria et al., 2022; Widodo et al., 2022). Antibiotic resistance bacteria (ARB) and antibiotic-resistant genes (ARG) from destroyed ARB can spread in the environment
(Courti et al., 2022; Tyasningsih et al., 2022). Unwise use of antibiotics in animals exacerbates the spread of ARBs and ARGs. Humans and animals excrete ARBs and ARGs through urine and feces into the environment
(Newton et al., 2015). Potential sources of AMR in poultry production consist of air, dust, soil, feed and rodents or other animals. From these sources, AMR bacteria and genes can be transmitted indirectly to the environment (
Martínez-Álvarez et al., 2022;
Effendi et al., 2018). Several studies have shown the role of air as a means of dissemination and survival both inside and outside the farm and poultry waste is considered the main vector for the spread of AMR bacteria
(Vounba et al., 2019; Hedman et al., 2020).
Large amounts of antibiotic residues are also excreted from the animal’s body (
Arsène et al., 2022). It is estimated that at least 70% of the total antibiotics consumed are excreted unchanged (
Kümmerer, 2009). The released antibiotic, after being reduced by metabolism, has a non-killing concentration, known as a sub-inhibitory concentration (
Vasilchenko and Rogozhin, 2019;
Ramandinianto et al., 2020). These antibiotics are mixed intensively with pathogenic bacteria in wastewater, more intense contact occurs in non-killing concentrations, the bacteria absorb the antibiotics and begin to adapt to them, eventually developing antibiotic resistance
(Rizzo et al., 2013; Riwu et al., 2020). This statement is also reinforced by other literature from
Meng et al., (2022) which states that waste from animals given antibiotics contains antibiotic residues and resistant bacteria. Other literature states that horizontal plasmid-mediated transfer of Antibiotic Resistance Genes (ARGs) is recognized as the most dominant way of spreading ARGs in humans, animals and the environment. Antibiotic selective pressure is considered to be one of the important contributors to promoting the spread of antibiotic resistance through horizontal gene transfer (HGT)
(Liu et al., 2020). ESBLs can also be spread
via HGT, as suggested by the study of
Franz et al., (2015) that
Escherichia coli-producing ESBL is at risk of spreading ARGs, especially in susceptible individuals.
Various genetic mechanisms are involved in the acquisition and spread of AMR (
Aminov, 2021). The
Escherichia coli mobilome includes a variety of mobile and mobilizable genetic elements, including plasmids, transposons, insertion sequences and integrons (intI), the latter of which is known to be involved in the spread of antibiotic resistance, especially among Gram-negative bacteria (
Gillings, 2014;
Pradika et al., 2019; Durairajan et al., 2021). Integrons are genetic structures that contain AMR genes in their variable regions (as gene cassettes) and have been detected in poultry farms in various studies
(Kalantari et al., 2021; Perez-Etayo et al., 2018). Another thing to worry about is that the ESBL-producing
Escherichia coli in this study is multidrug-resistant (MDR), even resistant to 5 classes of antibiotics. An isolate is defined as multidrug-resistant if it is insensitive to one or more antimicrobials in ³ 3 different antimicrobial classes
(Varga et al., 2019). ESBL-producing
Escherichia coli in livestock animals has become a public health concern in recent years
(Ansharieta et al., 2021). Infection in humans can cause treatment failure, prolonged illness and increase the death rate, especially in patients with septicemia and urinary tract infections
(Rodroo et al., 2021).
Based on the results of this research, it can be seen that poultry can be considered as a transmission medium for MDR bacteria, one of which is that ESBL plays a role in the spread of MDR into the environment which can ultimately pose a risk to public health. Antimicrobial resistance is a global and growing problem that requires a solution through a “One Health” approach (
Velazquez-Meza et al., 2022;
Yunita et al., 2020). Coordinated and appropriate action is needed to mitigate its impact now and in the future, as well as measures to ensure the economic
viability of the poultry sector along with public health security.