https://doi.org/10.52973/rcfcv-e34363
Received: 07/12/2023 Accepted: 13/02/2024 Published: 27/05/2024
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Revista Científica, FCV-LUZ / Vol. XXXIV, rcfcv-e34363
ABSTRACT
Avian pathogenic Escherichia coli (APEC) represents a major
challenge for the poultry industry, causing signicant economic
losses. This problem is exacerbated by the misuse use of antibiotics
in Veterinary Medicine, leading to the emergence of resistant strains
and thus creating a signicant risk to Public Health. This study,
carried out on 38 poultry farms in Algeria, involved the collection
of 200 samples for the isolation of E. coli strains. The resistance
of these strains to frequently used antibiotics was assessed using
the agar diffusion method. Multiple Correspondence Analysis (MCA)
was used to determine potential risk factors. The obtained results
revealed that E. coli was present in 30% of samples. Alarming levels
of resistance were observed against Tetracycline (81.6%), Ampicillin
(78.3%), Ciprooxacin (68.3%) and Nalidixic acid (60%). Stressful
environmental conditions in poultry houses, such as temperature
variations, high humidity, poor ventilation and stocking density were
identied as key factors in the development of avian colibacillosis. In
conclusion, the current study highlights the urgent need to strictly
monitor and regulate the use of antibiotics in Veterinary Medicine
and improve animal welfare in order to minimize the risk it pose to
Public Health originated in the farms. In addition, it is essential that
farmers maintain optimal environmental conditions in chicken rearing.
Key words: Algeria; antibiotic resistance; avian colibacillosis; avian
pathogenic; Escherichia coli; risk factors
RESUMEN
La Escherichia coli patógena aviar (EPA) representa un importante
reto para la industria avícola, causante de cuantiosas pérdidas
económicas. Este problema se ve agravado por el uso inadecuado
y excesivo de antibióticos en medicina veterinaria, que conduce a
la aparición de cepas resistentes y crea así un riesgo importante
para la salud pública. El presente estudio, realizado en 38 granjas
avícolas de Argelia, consistió en la recogida de 200 muestras para
el aislamiento de cepas de E. coli. La resistencia de estas cepas
a antibióticos de uso frecuente se evaluó mediante el método de
difusión en agar. Para determinar los posibles factores de riesgo se
utilizó el Análisis de Correspondencias Múltiples (ACM). Los resultados
obtenidos revelaron que E. coli estaba presente en el 30 % de las
muestras. Se observaron niveles alarmantes de resistencia frente a
la tetraciclina (81,6 %), la ampicilina (78,3 %), la ciprooxacina (68,3 %)
y el ácido nalidíxico (60 %). Las condiciones ambientales estresantes
en los gallineros, como variaciones de temperatura, mayor humedad,
ventilación deciente y densidad de población, se identicaron como
factores clave en el desarrollo de la colibacilosis aviar. En conclusión,
este estudio pone de relieve la urgente necesidad de vigilar y regular
estrictamente el uso de antibióticos en medicina veterinaria y mejorar
el bienestar animal para minimizar el riesgo para la salud pública.
Además, es esencial que los granjeros mantengan unas condiciones
ambientales óptimas en la cría de pollos.
Palabras clave: Argelia; resistencia a los antibióticos; colibacilosis
aviar; Escherichia coli; patógena aviar; factores de
riesgo
Epidemiological study and identication of Escherichia coli strains
associated with clinical events in Avian farming
Estudio epidemiológico e identicación de cepas de Escherichia
coli asociadas a episodios clínicos en avicultura
Sarah Saci
1
, Amine Msela
1
, Hillal Sebbane
1
, Bilal Saoudi
1
, Yousra Belounis
1
, Hakima Ait Issad
2
, Karim Houali
1
*
1
Université Mouloud Mammeri de Tizi–Ouzou, Laboratoire de Biochimie Analytique et Biotechnologies (LABAB). Tizi Ouzou, Algérie.
2
Université Mouloud Mammeri de Tizi–Ouzou, Laboratoire de ressources naturelles. Tizi Ouzou, Algérie.
Corresponding author: houalitizi@yahoo.fr
Escherichia coli associated with poultry farming / Saci et al. ________________________________________________________________________
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INTRODUCTION
Avian pathogenic Escherichia coli (APEC) is an extra–intestinal
pathogen responsible for local and systemic infections in poultry [1].
The most frequent manifestations of APEC infection in chickens (Gallus
gallus domesticus) include pericarditis, omphalitis, aerosacculitis, egg–
related peritonitis, salpingitis, cellulitis, as well as osteomyelitis, and
arthritis. These are commonly known as avian colibacillosis [2], which
is recognized as a disease with considerable economic consequences
in Algeria and Worldwide [3]. This leads to substantial losses, resulting
in high mortality and reduced performance [2].
APEC infections can be primary or secondary, if they occur because
of immunosuppressive disease or environmental stress. The bacteria
are introduced via the oral and respiratory tracts [4]. Chickens
become infected through contaminated feed and water and can be
transmitted to other birds via the fecal–oral route or by aerosol. In
addition, APEC can be transmitted vertically by infected breeding
stock via contaminated eggs [3].
The pathogenicity of APEC lies in its ability to deploy various virulence
and pathogenesis factors such as adhesins, invasins, toxins, host serum
resistance and iron acquisition systems [5]. These factors allow escape
from the host immune system, colonization and systemic dissemination
of APEC, facilitating the establishment of infection in poultry [5].
Antibiotics are widely used in the poultry industry to combat avian
colibacillosis. In many countries, the administration of antimicrobial
agents is not limited to therapeutic purposes [6]. Antimicrobials are also
used to improve productivity and feed conversion rates [4]. However, the
continued administration of these molecules leads to the emergence
of resistant strains [6]. These strains can be transmitted to humans
through the food chain, posing a serious risk to Human Health [6].
The aim of this study was to isolate and identify E. coli strains
associated with clinical events in poultry farms, to establish their
antibiotic resistance prole and to identify potential risk factors
contributing to the development of infection.
MATERIAL AND METHODS
Ethical statement
The animal experiment was approved by the Ethics Committee of
the Mouloud Mammeri University in Tizi–Ouzou. The committee gave
an approval number: UMMTO/2022/Ani021. Written informed consent
was obtained from all participants prior to publication of this study.
Samples collection
Two hundred samples were taken from organs (mixed liver and heart,
lungs, intestines, and joints) of sick chickens showing typical E. coli
lesions, from 38 poultry farms located in the wilaya of Tizi–Ouzou in
Algeria during the year 2022. Even if these animals are not intended for
consumption, resistant bacterial strains can potentially contaminate
the environment, other animals or people who come into contact with
them, which could ultimately present risks to public health.
Isolation and identication of isolates
Samples were crushed and homogenized in BHIB and incubated at
37 degrees for 24 h, then plated on Hektoen medium. Identication
of E. coli was based on morphological, microscopic and biochemical
differential tests, including oxidase, indole, urea and citrate permease,
then conrmed using the API 20E kit (Bio Mérieux, France).
Antibiotic susceptibility testing
Antimicrobial susceptibility was determined using Muller–Hinton
agar (Oxoid) disc diffusion method and interpreted according to CLSI
M100 2020, using interpretive categories zone diameters breakpoints
for each tested antibiotic. This approach allowed us to assess the
susceptibility of bacterial strains to the antibiotics used in our study
and classify them into 3 categories: susceptible, intermediate, and
resistant. It also allowed us to evaluate the current status of antibiotic
resistance in E. coli in the Algerian poultry industry, rather than the
effectiveness of clinical treatment. However, the epidemiological
investigation provides additional insights into the factors favoring
the occurrence of cases of avian colibacillosis, but is independent of
the study of antibiotic resistance [7]. The tested antibiotics (Oxoid,
UK) were: Ampicillin AMP (10 µg), Amoxicillin/Clavulanic acid AMC
(30µg), Piperacillin PIP (100 µg ), Cefazolin KZ (30 µg), Cefoxitin FOX
(30 µg), Cefotaxime CTX (30 µg), Ceftazidime CAZ (30 µg), Cefepime
FEP (30 µg), Aztreonam ATM (30 µg),Imipenem IMP (10 µg), Meropenem
MEM (10 µg), Gentamicin CN (10 µg/disc), Tetracycline TE (30 µg),
Sulfamethoxazole SXT (1.25/23.75 µg), Nalidixic acid NA (30 µg),
(20µg), Ciprooxacin CIP (5 µg), Amikacin AK (30 µg), Nitrofurantoin
N (300 µg) and Chloramphenicol CHL (30 µg). Escherichia coli ATCC
29522 strain was used as quality control. The panel of antibiotics
was selected taking into account their common use in the poultry
industry and their critical importance in human medicine.
Phenotypic detection of extended–spectrum beta–lactamases
(ESBL)
The presence of extended–spectrum beta–lactamases (ESBL)
was detected by the double–disk synergy method and conrmed by
the E–test CT/CLT.
Survey form
An investigation was carried out on these 38 poultry farms to collect
data on clinical episodes of avian colibacillosis. Information was
collected using a survey form, including variables such as age of
chickens, rearing season, number of birds, mortality and morbidity
rates, clinical symptoms, type of building, type of aeration, water
source, Feed type, humidity level and ventilation type. The data were
analyzed to identify trends and associated factors.
Statistical analysis
A Multiple Correspondence Analysis (MCA) was performed to
identify potential risk factors associated with colibacillosis, using
SPSS software (version 25.0).
RESULTS AND DISCUSSIONS
Isolation and identication
The prevalence of E. coli was estimated at 30%, while the remaining
isolates involving other germs, such as Klebsiella and Enterobacter.
46.6% Isolates were derived from different anatomical sites, with
the majority originating from the intestine (46.6%), followed by the
lungs (31.6%), the heart and liver (18.3%), and the joints (3.3%)..These
observations are discordant with the results of other studies carried
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FIGURE 1. Frequency of Antibiotic Resistance
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out in Algeria, such as Halfaoui et al. [8], who identied 156 strains
out of 180 samples (86.66%), and Benklaouz et al. [9], who recorded
145 isolates out of 290 samples (50%). These discrepancies in E. coli
detection rates could be attributed to a multitude of factors, including
the methodology used, the study period, environmental variations
and husbandry practices.
Antimicrobial susceptibility testing
According to the results of the disk diffusion test shown in
FIG. 1 and TABLE I, the highest rates of prevalent resistance were
recorded against TE and AMP, reaching 81.6% and 78.3%, respectively.
Percentage of resistance detected were also notable for PIP at 76.6%,
CIP at 68.3%, STX at 65%, and NA at 60%. CHL and KZ exhibited
resistance at rates of 33.3% and 28.33%, respectively. In contrast,
the antibiotics AMC, CTX, ATM, FEP, CN, and N showed relatively low
rates of resistance. All strains were susceptible to FOX, CAZ, IMP,
MEM and AK. Only one strain tested positive for ESBL production.
TABLE I
Results of antimicrobial susceptibility testing
Strains
AMP PIP AMC KZ FOX CAZ CTX ATM FEP IMP MEM NA AK TE CIP CN SXT N CHL
S ≥ 17
R ≤ 13
S ≥ 21
R ≤ 17
S ≥18
R≤13
S ≥ 23
R ≤ 19
S ≥ 18
R ≤ 14
S ≥ 21
R ≤ 17
S ≥ 26
R ≤ 22
S ≥ 21
R ≤ 17
S ≥ 25
R ≤ 18
S ≥ 23
R ≤ 19
S ≥ 22
R ≤ 18
S ≥19
R ≤ 13
S ≥ 17
R ≤ 14
S ≥ 15
R ≤ 11
S ≥ 26
R ≤ 21
S ≥ 15
R ≤ 12
S ≥ 16
R ≤ 10
S ≥ 17
R ≤ 14
S ≥ 18
R ≤ 12
E coli ATCC 25922
24 25 24 24 25 29 31 32 35 34 33 25 26 22 32 30 25 24 26
E1 6 17 17 21 22 29 30 30 34 30 33 6 25 15 12 25 6 20 6
E2 6 17 19 21 21 30 30 31 33 30 33 6 25 6 13 25 6 18 21
E3 6 12 18 17 22 30 29 30 33 30 33 6 21 6 6 22 27 23 6
E4 6 15 18 20 22 30 29 30 34 30 32 6 21 6 15 15 6 24 26
E5 6 17 21 20 22 31 29 25 34 32 33 6 23 6 17 20 6 22 6
E6 6 14 18 18 22 31 30 30 34 32 33 15 23 6 25 25 6 29 6
E7 6 17 22 21 22 30 29 33 34 30 32 6 21 6 14 19 6 27 6
E8 18 29 21 22 22 27 30 30 35 30 33 21 22 23 35 20 27 23 25
E9 6 16 19 20 22 30 30 30 35 30 32 6 21 6 13 20 6 17 24
E10 17 25 20 22 22 30 30 28 35 30 32 6 20 21 21 20 21 19 24
E11 6 12 17 17
22 26 23 29 33 30 33 6 19 6 6 24 29 21 24
E12 6 15 19 20 21 25 29 30 31 30 29 12 21 6 20 16 6 25 24
E13 6 16 18 20 24 29 29 26 30 30 29 16 19 6 21 16 30 24 24
E14 21 28 22 24 22 30 29 30 33 30 30 15 21 14 25 21 6 29 6
E15 6 22 20 21 22 31 28 35 34 31 33 6 21 6 21 20 6 27 6
E16 6 18 18 20 21 27 29 30 33 30 30 6 21 10 31 20 6 27 25
E17 0 15 16 15 22 30 28 32 34 30 32 6 22 6 12 18 6 21 6
E18 6 17 18 20 18 30 26 30 35 30 32 6 21 6 16 18 6 25 6
E19 6 15 18 20 22 29 23 30 34 30 30 6 22 6 10 19 6 15 6
E20 6 12 16 18 22 28 25 30 34 30 30 6 20 6 6 20 6 25 6
E21 6 12 17 19 22 27 23 30 33 30 30 18 22 6 27 18 6 21 6
E22 6 14 16 17 22 28 25 30 34 30 30 6 23 6 11 20 30 19 22
E23 6 18 18 18 22 30 25 30 33 30 30 6 22 27 14 20 6 25 15
E24 6 18 16 20 23 30 25 30 33 32 30 6 21 6 6 20 6 19 6
E25 6 14 22 20 22 28 30 29 31 30 30 6 21 6 10 21 20 22 20
Escherichia coli associated with poultry farming / Saci et al. ________________________________________________________________________
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E26 6 15 18 20 20 27 23 28 33 30 30 6 19 6 9 19 6 16 22
E27 6 15 16 18 20 28 24 29 34 30 30 6 22 6 6 6 6 22 6
E28 6 16 18 20 20 28 23 30 34 30 30 6 20 6 10 20 6 17 24
E29 6 15 11 18 16 28 22 30 34 30 30 6 22 6 6 6 6 22 6
E30 6 10 20 6 25 22 6 15 18 30 30 6 21 6 25 18 6 25 25
E31 6 17 13 13 18 25 20 30 34 31 30 6 22 6 10 19 6 20 6
E32 6 16 20 20 22 31 25 31 35 30 30 6 22 6 27 6 20 22 24
E33 6 17 21 15 22 33 34 30 33 35 34 6 19 6 22 18 20 21 20
E34 6 17 21 14 22 30 29 29 32 33 32 6 20 6 6 18 6 21 22
E35 19 25 24 23 22 29 30 29 32 33 32 6 20 6 6 18 6 15 21
E36 20 27 24 23 24 31 32 32 33 31 31 6 20 6 26 20 20 22 24
E37 6 13 22 13 24 29 31 29 30 31 30 6 22 6 6 18 6 23 24
E38 6 14 20 18 22 32 33 30 30 32 30 6 20 6 6 12 6 22 23
E39 6 15 23 12 22 30 29 30 30 33 32 6 20 6 6 19 6 21 21
E40 6 17 23 21 21 28 31 30 30 33 32 6 21 6 6 25 6 14 23
E41 6 12 20 16 24 31 33 30 30 30 32 6 20 6 6 6 6 18 23
E42 6 16 22 22 24 30 32 30 30 32 30 19 20 6 15 23 6 19 21
E43 6 18 22 21 23 30 32 30 32 30 30 19 20 6 6 25 26 21 24
E44 6 16 22 20 24 30 32 30 31 30 31 20 20 6 33 25 6 20 23
E45 21 27 24 29 24 30 30 32 31 30 30 19 18 6 25 23 6 21 21
E46 21 30 24 28 25 33 34 30 34 31 30 19 22 6 25 27 27 21 20
E47 6 15 24 20 25 28 29 30 30 30 31 20 20 6 6 24 6 22 6
E48 20 23 20 18 25 30 30 30 32 30 31 20 20 25 30 25 27 22 20
E49 6 15 23 20 25 26 30 30 32 30 30 20 20 6 15 25 6 21 25
E50 6 15 22 20 23 29 30 30 32 33 30 19 20 6 27 25 24 18 24
E51 25 31 25 25 25 31 30 31 35 32 31 21 23 25 27 18 25 18 27
E52 6 16 21 22 25 30 31 31 34 33 32 20 23 6 12 28 6 19 6
E53 6 13 20 20 24 30 31 30 34 30 32 19 20 6 6 24 6 20 20
E54 6 16 21 20 24 30 31 31 35 32 30 19 20 6 15 24 25 19 21
E55 20 29 24 22 25 29 32 31 33 32 31 19 22 25 28 24 26 20 26
E56 20 28 24 23 25 31 30 32 35 32 31 19 21 25 30 34 26 19 25
E57 6 15 19 20 22 31 30 30 34 32 31 21 19 6 6 24 6 19 6
E58 6 16 24 20 25 30 30 30 32 30 31 21 22 6 6 26 6 21 6
E59 19 30 22 23 25 29 30 31 35 30 31 21 20 23 30 24 25 22 25
E60
19 27 21 23 25 30 32 31 34 30 31 20 20 22 30 24 23 21 21
TABLE I
Results of antimicrobial susceptibility testing (cont...)
A multiresistant strain is a bacterium that exhibits resistance to
at least three different classes of antimicrobials [6]. In this study,
80% of isolates were found to be multi–resistant to at least three
different classes of antibiotics. Specic resistance rates were 15.33%
for ve classes of antibiotics, 26.66% for six classes and 18.33% for
seven classes. A high prevalence of multiresistance (56.66%) was
observed for six specic antibiotics (TE, AMP, PIP, CIP, STX, NA). A
total of 32 antibiotypes were obtained from APEC isolates (Table II),
antibiotic proles are the result of the agar diffusion test, reecting
a diversity of antibiotic sensitivity/resistance among isolated strains
and providing information on the state of antibiotic resistance in the
poultry sector. The most prevalent resistance prole being: AML,
PIP, NA, TE, CIP, SXT, CHL.
In the present study, it was examined the resistance of E. coli strains to
19 antibiotics. Tetracycline showed the highest rate of resistance (81.6%),
which is similar to the results reported by Aggad et al. [10] and Belmahdi et
al. [11], where resistance rates were 87 and 90%, respectively. Resistance
to Ampicillin (78.3%) was comparable to the ndings of Halfaoui et al. [8]
and Mansouri et al. [12] in Algeria, and Dou et al. [13] in China, where the
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that some microorganisms use coregulation, a mechanism based
on regulatory proteins, to coordinate resistance to heavy metals
and antibiotics, enabling them to simultaneously develop defense
mechanisms against both types of substance [16].
Ciprofloxacin showed a resistance rate of 68.33%, which
corroborates the results obtained by Meguenni et al. [17]. Regarding
Nalidixic acid, in the present study revealed a resistance rate of 60%,
which remains lower than that reported by some studies carried out
in Algeria, which reported rates ranging from 90 to 95% [18, 19].
Veterinarians often use Nalidixic acid and Ciprooxacin to prevent early
chick mortality and contain the spread of avian diseases, due to their
affordability on the Algerian market [20]. However, the widespread
use of quinolones and uoroquinolones in poultry farming has led
to a growing problem of resistance. Part of this resistance could be
attributed to the persistence of residues of these antibiotics in poultry
drinking water [21]. Chickens consuming water contaminated with
these residues progressively develop resistance, especially in the event
of prolonged exposure to antibiotics, thus promoting the transfer of
resistance genes between different bacteria in the gastrointestinal
tract [22]. It is essential to note that quinolones and uoroquinolones
are classied as "critically important antimicrobials" by the World
Health Organization (WHO), due to their importance in Human Medicine
[23]. Resistance of avian bacteria to these antibiotics may represent
a risk to Human Health due to their potential transmission through
the food chain via cross–contamination [24].
The rate of resistance to Trimethoprim sulfonamides was 65%,
concordant with the ndings of Benameur et al. [25] and Aberkane
et al. [19]. Even higher resistance rates (95.5%) were observed in
the study by Ibrahim et al. [26] in Jordan. The difference could be
attributed to a variety of factors, including variations in bacterial
strains, antibiotic use practices and local conditions specic to each
Region. These molecules are commonly used in Veterinary Medicine
to prevent and treat various avian diseases, which could explain the
high levels of resistance observed [27].
The rate of resistance to Chloramphenicol was 33.33%, similar
to the results of Halfaoui et al. [8]. This resistance could be due to
the persistence of pre–existing resistances or to the misuse of this
substance, as it is prohibited in the breeding context, as well as to
the phenomenon of co–selection [28].
Resistance to Cefazolin (28.33%) could be explained by co–selection
resulting from the frequent or inappropriate use of other antibiotics
in the same class, such as Ampicillin [29]. The low resistance to
Gentamicin (8.3%) agrees with the study carried out by Levy et al. [3]
in Bangladesh (8.3%) and by Kiiti et al. [30] in Tanzania. This could be
the result of inappropriate use, given that this antibiotic is banned in
Veterinary Medicine in Algeria. By comparing our results to previous
studies, we may observe a trend towards an increase in antimicrobial
resistance, but this would require in–depth data analysis and an
understanding of contextual factors specic to each study [17].
The molecules AMC, CTX, ATM, FEP and N showed the lowest
resistance rates, with only 1.6% resistance. It should be noted that
these antibiotics are not used in Veterinary Medicine [8]. While all E.
coli strains were sensitive to FOX, CAZ, IMP, MEM and AK, as these
substances are not used in avian pathology [31, 32].
Finally, only one strain was identified as positive for ESBL
production. Such strains have also been reported by Benklaouz etal.
[9] and Halfaoui et al. [8]. Recent studies have shown a widespread
TABLE II
Antibiotic resistance proles of isolated strains
Strains Antibiotypes
E1
AMP, PIP, NA, CIP, SXT, CHL
E2, E12 AMP, PIP, NA, TE, CIP, SXT
E3 AMP, PIP, KZ, NA, TE, CIP, CHL
E4, E16, E28 AMP, PIP, NA, TE, CIP, SXT
E5, E7, E24, E20, E17, E18, E19 AMP, PIP, NA, TE, CIP, SXT, CHL
E6 AMP, PIP, KZ, TE, SXT, CHL
E9, E47, E52, E57, E58 AMP, PIP, TE, CIP, SXT, CHL
E10 AN, CIP
E11, E22 AMP, PIP, KZ, NA, TE, CIP
E14 SXT, CHL
E15 AMP, NA, TE, CIP, SXT, CHL
E21 AMP, PIP, KZ, TE, SXT, CHL
E23 AMP, PIP, KZ, NA, CIP, SXT
E25 AMP, PIP, NA, TE, CIP
E26 AMP, PIP, NA, TE, CIP, SXT
E27 AMP, PIP, KZ, NA, TE, CIP, CN, SXT, CHL
E29 AMP, PIP, AMC, KZ, NA, TE, CIP, CN, SXT, CHL
E30 AMP, PIP, KZ, CTX, ATM, FEP, NA, TE, SXT
E31 AMP, PIP, AMC, KZ, NA, TE, CIP, SXT, CHL
E32 AMP, PIP, NA, TE, CN
E33 AMP, PIP, KZ, NA, TE
E34, E37, E39 AMP, PIP, KZ, NA, TE, CIP, SXT
E35 NA, TE, CIP, SXT
E36 NA, TE
E38, E41 AMP, PIP, KZ, NA, TE, CIP, CN, SXT
E40 AMP, PIP, KZ, NA, TE, CIP, SXT, F
E42, E49, E53, E13 AMP, PIP, TE, CIP, SXT
E43, E54 AMP, PIP, TE, CIP
E44 AMP, PIP, TE, SXT
E45 TE, SXT
E46 TE
E50
AMP, PIP, TE
resistance rate was 80.3%. The high levels of resistance to Tetracycline
and Ampicillin are partly due to their prolonged use as growth promoters
and therapeutic treatments in the poultry sector [14].
In addition, the incorporation of heavy metals into poultry feed
as additives has enabled bacteria to acquire resistance to these
metals [15], which can be accompanied by antibiotic resistance due
to the phenomenon of co–selection. Indeed, metal and antibiotic
resistance genes can be located on the same genetic structure,
such as plasmids or transposons [15]. This phenomenon has been
observed in a variety of situations, including co–resistance to copper,
silver, mercury and tetracycline; and co–resistance to copper, silver,
β–lactam and uoroquinolone [16]. In addition, it has been reported
FIGURE 2. Multiple Correspondence Analysis. (A) Joint Plot of Category Points.
(B) Object Points Labeled by Observation Numbers. (C) Discrimination Measures
A
B
C
Escherichia coli associated with poultry farming / Saci et al. ________________________________________________________________________
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spread of ESBL–producing E. coli in animals intended for human
consumption in Algeria, despite the rare use of third generation
Cephalosporins in poultry farming [11]. This resistance could result
from the selection of ESBL–producing E. coli strains due to excessive
use of other antibiotics, notably quinolones [9]. Furthermore, the
use of Ampicillin could favour the appearance of mutations leading
to the emergence of ESBL–producing mutants derived from the bla
TEM–1 or bla SHV–1 genes [28].
Frequent use of antimicrobial agents results in selective pressure
leading to resistance to anti–APEC antimicrobials [33]. In addition,
the constant use of low–dose antibiotics in poultry feed, mainly for
growth promotion, promotes the production and spread of antibiotic
resistance genes, thus contributing to the emergence of antibiotic
resistance [21].
The increasing use of disinfectants also plays a role in the rise of
bacterial resistance [34]. It has been reported that antibiotic resistance
is not solely dependent on the use of antibiotics but may also result from
excessive use of disinfectants and biocides [33], as these products
contribute to the cross–selection of resistance mechanisms [27].
Risk factors
Multiple correspondence Analysis (MCA) revealed two principal
components: dimension 1 and dimension 2 (FIG. 2–A, B).
The most discriminating variables for axis 1 are: type of building,
season, clinical symptoms, water source and soil type, while for axis
2, they are: age and stocking density. The most relevant variables
are age, density, building type and symptoms (FIG. 2–C). Age is
signicantly correlated with building type, density is correlated with
symptoms, and season is correlated with soil type and building type.
According to the survey (TABLE III), the majority of colibacillosis–
infected chickens (n=55) are separated into two groups, the rst in
the start–up phase (58.33%) and the second in the growth phase
(30%). They are generally housed in solid–structure buildings (90.0%),
and rearing takes place either in winter (50%) or spring (26.66%).
Population density remains high in 76.66% of cases, with more than
2,000 individuals per building, and drinking water comes mainly from
the tap in 75% of cases. The most frequent symptoms are severe
diarrhoea (50%) and respiratory disorders (31.66%).
A minority group of infected chickens (n=5) are in the nishing phase
and are housed in greenhouse–type buildings during the summer
season, with numbers exceeding 6,000 individuals per building. These
birds tended to drink well water and showed joint symptoms.
It is also interesting to note that there is a small group of infected
chickens (6.66%) that share some common factors with the two
previously mentioned groups.
The results of the MCA indicate that poultry age, numbers,
symptoms, type of construction, season, soil type and water source
are key factors to consider when assessing the risks associated with
avian colibacillosis in poultry ocks [2, 35].
Due to the development of their immune systems, young chickens
are more vulnerable to bacterial infections, particularly secondary
infections [36].
Colibacillosis in poultry can manifest itself in different ways throughout
their growth [37]. Common symptoms include diarrhoea, caused by
invasion of the intestinal mucosa by E. coli, leading to inammation
and disruption of intestinal function [38]. In addition, APEC infections
can cause respiratory problems [38]. Finally, although less common,
joint stiffness can occur when the bacterium spreads through the
bloodstream, reaching the joints and causing painful inammation
that results in stiffness and diculty of movement in chickens [39].
The systematic use of gas incubators to heat rearing buildings
in winter can pose problems of temperature regulation, which can
have signicant consequences for chicken health. Chickens are
TABLE III
Survey Sheet Results
Risk Factors Prevalence
Stage
• Start–up phase 58.33%
• Growth phase 30%
• Finishing phase 11.66%
Rearing season
• Winter 50.0%
• Spring 26.66%
• Summer 23.33%
• Autumn 0%
Number of chickens by building
• > 2000 76,66%
• > 6000 23,33%
Construction type
• Bulding 90.0%
• Greenhouse 10.0%
Soil type
• Hard ooring 78.33%
• Clay ooring 21.66%
Feed type Pellets
Water source
• Urban water supply 75%
• Well water 25%
Ventilation type
• Dynamic ventilation dynamique 100.0%
• Others ventilation systems 0.0%
Pre–treatment with antibiotics 100%
Humidity level High
Clinical symptoms
• Severe diarrhea 50%
• Respiratory disorders 31.66
• Joint stiness 3.33%
• Death with no apparent symptoms 15%
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particularly sensitive to these temperature uctuations, as they
have no sweat glands and therefore rely heavily on thermal regulation
by their feathers [37]. Heat stress can have a negative impact on
chickens' performance, physiology and general health, and can make
them more susceptible to infections, particularly colibacillosis [40].
In some cases, there is not enough space to contain the number
of birds, which can lead to overcrowding. Overcrowding is known
to induce stress in poultry, which can have a negative impact on
their immune systems [41]. Stress disrupts various physiological
functions and leads to reduced feed intake and growth, increasing
their susceptibility to disease and reducing their ability to mount
effective immune responses [35].
Poultry farms using solid buildings show a higher prevalence of the
disease, which could be due to inadequate ventilation, favoring the
accumulation of humidity and ammonia gases, which could stimulate
the chickens' mucous membrane and cause pathological lesions of
the tissues of the trachea and lungs [42]. These conditions offer a
breeding ground for the bacteria responsible for colibacillosis [43].
Hard oors in livestock facilities have a rigid, porous surface,
making them dicult to clean eciently [44, 45]. This characteristic
promotes the accumulation of dirt, organic debris and bacteria on
oor surfaces [46]. In addition, these surfaces are conducive to the
formation of biolm, a microbial matrix that protects bacteria from
cleaning and disinfection procedures [47].
Drinking water for poultry is not subject to any specic regulations
in terms of microbiological, chemical and physical criteria [48].
This situation creates a potential opportunity for the transmission
of pathogenic micro–organisms and contaminants and may also
compromise the ecacy of drugs administered in the water [48]. In
addition, the accumulation of organic matter in water supply systems,
such as tanks, drinking troughs and battery pipes, could create a habitat
conducive to the multiplication of micro–organisms in water [49].
Stressful environmental conditions in poultry houses, such as
temperature variations, excessive humidity, poor ventilation and
high stocking density, weaken the poultry immune system, making
them more vulnerable to colibacillosis and other types of infections
besides affecting animal welfare [35]. This disease is frequently
treated with antibiotics, but inappropriate use creates antibiotic
resistance, complicating treatment [50].
CONCLUSION
In conclusion, the emergence of multi–resistant strains of avian
pathogenic Escherichia coli represents a growing threat to Animal and
Public Health, as they compromise the ecacy of medical treatments
and have the potential to spread between animals and humans. This
study highlights the signicant impact of stressful environmental
conditions on the prevalence of colibacillosis in poultry. Indeed, to
reduce the risks associated with this disease, it is crucial that poultry
farmers and managers maintain optimal environmental conditions
to minimize stress. At the same time, appropriate use of antibiotics
is essential to maintain their continued effectiveness in treating
bacterial infections. Concerted efforts involving both the livestock
sector, health authorities, and researchers are necessary to curb
the emergence of antibiotic resistance and preserve the ecacy of
these critical drugs, for both animal and public health.
Availability of data and materials
The data sets during and/or analyzed during the current study
are available from the corresponding author on reasonable request
ACKNOWLEDGEMENTS
The authors would like to thank the poultry breeders of Tizi–Ouzou
for their collaboration and contribution to this study.
Financial support
This work was supported by the Algerian Ministry of Higher
Education and Scientic Research.
Escherichia coli associated with poultry farming / Saci et al. ________________________________________________________________________
8 of 10
Conict of interest
The authors declare no conict of interest.
Author contributions
S.S. performed experiments and wrote the manuscript. A.M H.S. co–
directing work, S.S, Y.B, H.A.I. performed experiments, B.S. Statistical
analysis, K.H. Directing work and onceived the experiments.
BIBLIOGRAPHIC REFERENCES
[1] Tuntufye HN, Lebeer S, Gwakisa PS, Goddeeris BM. Identication
of avian pathogenic Escherichia coli genes that are induced
in vivo during infection in chickens. Appl. Environ. Microbiol.
[Internet]. 2012; 78(9):3343–3351. doi: https://doi.org/mxx3
[2] Kathayat D, Lokesh D, Ranjit S, Rajashekara G. Avian pathogenic
Escherichia coli (APEC): an overview of virulence and
pathogenesis factors, zoonotic potential, and control strategies.
Pathog. [Internet]. 2021; 10(4):467. doi: https://doi.org/gkg675
[3] Ievy S, Islam MS, Sobur MA, Talukder M, Rahman MB, Khan MFR,
Rahman MT. Molecular detection of avian pathogenic Escherichia
coli (APEC) for the rst time in layer farms in Bangladesh and
their antibiotic resistance patterns. Microorg. [Internet]. 2020;
8(7):1021. doi: https://doi.org/mxx4
[4] Koutsianos D, Athanasiou LV, Mossialos D, Franzo G, Cecchinato
M, Koutoulis KC. Investigation of Serotype Prevalence of
Escherichia coli Strains Isolated from Layer Poultry in Greece and
Interactions with Other Infectious Agents. Vet. Sci. [Internet].
2022; 9(4):152. doi: https://doi.org/mxx5
[5] Ghorbani AR, Khoshbakht R, Kaboosi H, Shirzad–Aski H,
Ghadikolaii FP. Phylogenetic relationship and virulence gene
proles of avian pathogenic and uropathogenic Escherichia
coli isolated from avian colibacillosis and human urinary tract
infections (UTIs). Iranian J. Vet. Res. [Internet]. 2021; 22(3):203–
208. doi: https://doi.org/mxx6
[6] Subedi M, Luitel H, Devkota B, Bhattarai RK, Phuyal S, Panthi
P, Chaudhary DK. Antibiotic resistance pattern and virulence
genes content in avian pathogenic Escherichia coli (APEC) from
broiler chickens in Chitwan, Nepal. BMC Vet. Res. [Internet].
2018; 14:113. doi: https://doi.org/j885
[7] CLSI. Performance Standards for Antimicrobial Susceptibility
Testing. 30th ed. Wayne, Pennsylvania, USA: Clinical and Laboratory
Standards Institute: 2020. 402 p. (CLSI Supplement M100).
[8] Halfaoui Z, Menoueri NM, Bendali LM. Serogrouping and antibiotic
resistance of Escherichia coli isolated from broiler chicken with
colibacillosis in the center of Algeria. Vet. World. [Internet].
2017; 10(7):830–835. doi: https://doi.org/mxzb
[9] Benklaouz MB, Aggad H, Benameur Q. Resistance to multiple
rst–line antibiotics among Escherichia coli from poultry in
Western Algeria. Vet. World. [Internet]. 2020; 13(2):290–295.
doi: https://doi.org/mxzc
[10] Aggad H, Ammar YA, Hammoudi A, Kihal M. Antimicrobial
resistance of Escherichia coli isolated from chickens with
colibacillosis. Glob. Vet. [Internet] 2010 [cited 10 Nov. 2023];
4(3):303–306. Available in: https://goo.su/sA1pop
[11] Belmahdi M, Chenouf NS, Ait Belkacem A, Martinez–Alvarez S,
Pino–Hurtado MS, Benkhechiba Z, Torres C. Extended Spectrum
β–Lactamase–Producing Escherichia coli from Poultry and Wild
Birds (Sparrow) in Djelfa (Algeria), with Frequent Detection of
CTX–M–14 in Sparrow. Antibiot. [Internet]. 2022; 11(12):1814. doi:
https://doi.org/mxzf
[12] Mansouri N, Aoun L, Dalichaouche N, Hadri D. Yields, chemical
composition, and antimicrobial activity of two Algerian essential oils
against 40 avian multidrug–resistant Escherichia coli strains. Vet.
World. [Internet]. 2018; 11(11):1539–1550. doi: https://doi.org/mxzh
[13] Dou X, Gong J, Han X, Xu M, Shen H, Zhang D, Zou J. Characterization
of avian pathogenic Escherichia coli isolated in eastern China. Gene.
[Internet]. 2016; 576(1 part 2):244–248. doi: https://doi.org/f8bbzf
[14] Granados–Chinchilla F, Rodríguez C. Tetracyclines in food and
feedingstuffs: from regulation to analytical methods, bacterial
resistance, and environmental and health implications. J. Analyt.
Meth. Chem. [Internet]. 2017; 2017:1315497. doi: https://doi.org/gtk6nv
[15] Oyewale AT, Adesakin TA, Aduwo AI. Environmental impact of
heavy metals from poultry waste discharged into the Olosuru
stream, Ikire, southwestern Nigeria. J. Health Pollut. [Internet].
2019; 9(22):190607. doi: https://doi.org/mxzj
[16] Salam LB. Unravelling the antibiotic and heavy metal resistome
of a chronically polluted soil. 3 Biotech. [Internet]. 2020; 10:238.
doi: https://doi.org/mxzm
[17] Meguenni N, Chanteloup N, Tourtereau A, Ahmed CA, Bounar–
Kechih S, Schouler C. Virulence and antibiotic resistance prole
of avian Escherichia coli strains isolated from colibacillosis
lesions in the central of Algeria. Vet. World. [Internet]. 2019;
12(11):1840–1848. doi: https://doi.org/mxzk
[18] Belmahdi M, Bakour S, Al Bayssari C, Touati A, Rolain JM.
Molecular characterisation of extended–spectrum β–lactamase–
and plasmid AmpC–producing Escherichia coli strains isolated
from broilers in Béjaïa, Algeria. J. Glob. Antimicrob. Resist.
[Internet]. 2016; 6:108–112. doi: https://doi.org/mxzn
[19] Aberkane C, Messaï A, Messaï CR, Boussaada T. Antimicrobial
resistance pattern of avian pathogenic Escherichia coli with
detection of extended–spectrum β–lactamase–producing
isolates in broilers in east Algeria. Vet. World. [Internet]. 2023;
16(3):449–454. doi: https://doi.org/mxzq
[20] Ramalho R, Mezzomo LC, Machado W, da Silva–Morais, Hein
C, Müller CZ, da Silva TCB, Martins AF. The occurrence of
antimicrobial residues and antimicrobial resistance genes in
urban drinking water and sewage in Southern Brazil. Brazilian
J. Microbiol. [Internet]. 2022; 53(3):1483–1489. doi: https://doi.
org/mxzr
[21] Jian Z, Zeng L, Xu T, Sun S, Yan S, Yang L, Dou T. Antibiotic
resistance genes in bacteria: Occurrence, spread, and control. J.
Basic Microbiol. [Internet]. 2021; 61(12):1049–1070. doi: https://
doi.org/gm5892
[22] Lee YJ, Jung HR, Yoon S, Lim SK, Lee YJ. Situational analysis
on uoroquinolones use and characterization of high–level
ciprooxacin–resistant Enterococcus faecalis by integrated
broiler operations in South Korea. Front. Vet. Sci. [Internet].
2023; 10:1158721. doi: https://doi.org/mxzs
_____________________________________________________________________________Revista Cientifica, FCV-LUZ / Vol. XXXIV, rcfcv-e34363
9 of 10
[23] Schmerold I, Gelswk IV, Gehring R. European regulations on
the use of antibiotics in veterinary medicine. Eur. J. Pharm. Sci.
[Internet]. 2023; 189:106473. doi: https://doi.org/mxzt
[24] Benameur Q, Guemour D, Hammoudi A, Aoudia H, Aggad H,
Humblet MH, Saegermang C. Antimicrobial resistance of
Escherichia coli isolated from chickens in West of Algeria. Intern.
J. Sci. Basic Appl. Res. [Internet]. 2014 [cited 15 Nov. 2023];
13(1):366–370. Available in: https://goo.su/OJ6U
[25] Ibrahim RA, Cryer TL, La SQ, Basha EA, Good L, Tarazi YH.
Identication of Escherichia coli from broiler chickens in Jordan,
their antimicrobial resistance, gene characterization and the
associated risk factors. BMC Vet. Res. [Internet]. 2019; 15:159.
doi: https://doi.org/mxzv
[26] EFSA Panel on Biological Hazards (BIOHAZ), Koutsoumanis K,
Allende A, Alvarez‐Ordóñez A, Bolton D, Bover‐Cid S, Chemaly M,
Davies R, De Cesare A, Herman L, Hilbert F, Lindqvist R, Nauta
M, Ru G, Simmons M, Skandamis P, Suffredini E, Andersson DI,
Bampidis V, Bengtsson–Palme J, Bouchard D, Ferran A, Kouba
M, López Puente S, López–Alonso M, Nielsen SS, Pechova A,
Petkova M, Girault S, Broglia A, Guerra B, Innocenti ML, Liébana
E, López–Gálvez G, Manini P, Stella P, Peixe L. Maximum levels of
cross‐contamination ML, for 24 antimicrobial active substances
in non‐target feed. Part 12: Tetracyclines: tetracycline,
chlortetracycline, oxytetracycline, and doxycycline. EFSA J.
[Internet]. 2021; 19(10): e06864. doi: https://doi.org/gnsd9t
[27] Campos J, Cristino L, Peixe L, Antunes P. MCR–1 in multidrug–
resistant and copper–tolerant clinically relevant Salmonella
1,4,[5],12:i:–and S. Rissen clones in Portugal, 2011 to 2015. Euro
surveill. [Internet]. 2016; 21(26):30270. doi: https://doi.org/mx2g
[28] Baquero F, Martínez JL, Novais Â, Rodríguez–Beltrán J, Martínez–
García L, Coque TM, Galán JC. Allogenous selection of mutational
collateral resistance: old drugs select for new resistance within
antibiotic families. Front. Microbiol. [Internet]. 2021; 12:757833.
doi: https://doi.org/mx2h
[29] Kiiti RW, Komba EV, Msoffe PL, Mshana SE, Rweyemamu M,
Matee MI. Antimicrobial resistance proles of Escherichia coli
isolated from broiler and layer chickens in Arusha and Mwanza,
Tanzania. Intern. J. Microbiol. [Internet]. 2021; 2021:6759046.
doi: https://doi.org/mx2j
[30] Kakooza S, Munyiirwa D, Ssajjakambwe P, Kayaga E, Tayebwa DS,
Ndoboli D, Kaneene JB. Epidemiological dynamics of extended–
spectrum β–lactamase– or AmpC β–lactamase–producing
Escherichia coli screened in apparently healthy chickens in
Uganda. Scientica [Internet]. 2021; 2021:3258059. doi: https://
doi.org/gnwvjs
[31] Banik GR, Durayb B, King C, Rashid H. Antimicrobial resistance
following prolonged use of hand hygiene products: a systematic
review. Pharmacy. [Internet]. 2022; 10(1):9. doi: https://doi.org/mx2k
[32] Witte W. Selective pressure by antibiotic use in livestock. Intern.
J. Antimicrob. Agents. [Internet]. 2000; 16(Suppl. 1):19–24. doi:
https://doi.org/d572nd
[33] Cheng G, Hao H, Xie S, Wang X, Dai M, Huang L, Yuan Z. Antibiotic
alternatives: the substitution of antibiotics in animal husbandry.
Front. Microbiol. [Internet]. 2014; 5:217. doi: https://doi.org/gh5tqv
[34] Rozman U, Pušnik M, Kmetec S, Duh D, Šostar–Turk S. Reduced
susceptibility and increased resistance of bacteria against
disinfectants: A systematic review. Microorganisms. [Internet].
2021; 9(12):2550. doi: https://doi.org/mx2m
[35] Abo–Al–Ela HG, El–Kassas S, El–Naggar K, Abdo SE, Jahejo AR,
Al Wakeel RA. Stress and immunity in poultry: light management
and nanotechnology as effective immune enhancers to ght
stress. Cell Stress Chaperones. [Internet]. 2021; 26(3):457–472.
doi: https://doi.org/mx2n
[36] Song B, Tang D, Yan S, Fan H, Li G, Shahid MS, Guo Y. Effects
of age on immune function in broiler chickens. J. Anim. Sci.
Biotechnol. [Internet]. 2021; 12:42. doi: https://doi.org/gqws22
[37] Wickramasuriya SS, Park I, Lee K, Lee Y, Kim WH, Nam H, Lillehoj
HS. Role of physiology, immunity, microbiota, and infectious
diseases in the gut health of poultry. Vaccines. [Internet]. 2022;
10(2):172. doi: https://doi.org/mx2q
[38] Drancourt M. 38 – Acute diarrhea. In: Cohen J, Powderly WG,
Opal SM, editors. Infectious Diseases 4th ed. [Internet]. London:
Elsevier; 2017. 1:335–340.e2. doi: https://doi.org/mx2r
[39] Oh JY, Kang MS, An BK, Song EA, Kwon JH, Kwon YK. Occurrence
of purulent arthritis broilers vertically infected with Salmonella
enterica serovar Enteritidis in Korea. Poult. Sci. [Internet]. 2010;
89(10):2116–2122. doi: https://doi.org/bg34g6
[40] Uyanga VA, Musa TH, Oke OE, Zhao J, Wang X, Jiao H, Onagbesan
OM, Lin H. Global trends and research frontiers on heat stress
in poultry from 2000 to 2021: A bibliometric analysis. Front.
Physiol. [Internet]. 2023; 14:1123582. doi: https://doi.org/mx2t
[41] Heckert RA, Estevez I, Russek–Cohen E, Pettit–Riley R. Effects of
density and perch availability on the immune status of broilers. Poult.
Sci. [Internet]. 2002; 81(4):451–457. doi: https://doi.org/mx2v
[42] Wlaźlak S, Pietrzak E, Biesek J, Dunislawska A. Modulation of the
immune system of chickens, a key factor in maintaining poultry
production—a review. Poult. Sci. [Internet]. 2023; 102(8):102785.
doi: https://doi.org/mx2w
[43] Liu QX, Zhou Y, Li XM, Ma DD, Xing S, Feng JH, Zhang MH.
Ammonia induces lung tissue injury in broilers by activating
NLRP3 inflammasome via Escherichia/Shigella. Poult. Sci.
[Internet]. 2020; 99(7):3402–3410. doi: https://doi.org/mx2x
[44] Ismaïl R, Aviat F, Michel V, Le Bayon I, Gay–Perret P, Kutnik M,
Fédérighi M. Methods for recovering microorganisms from solid
surfaces used in the food industry: a review of the literature. Int.
J. Environ. Res. Public Health. [Internet]. 2013; 10(11):6169–6183.
doi: https://doi.org/f5jkr2
[45] Artasensi A, Mazzotta S, Fumagalli L. Back to basics: Choosing
the appropriate surface disinfectant. Antibiotics. [Internet].
2021; 10(6):613. doi: https://doi.org/gk7zvj
[46] Capria VM, Fernandez MO, Walker MM, Bergdall VK. Comparison
of oor cleaning and disinfection processes in a research animal
facility. J. Am. Assoc. Lab. Anim. Sci. [Internet]. 2022; 61(6):644–
649. doi: https://doi.org/mx2z
[47] Carrascosa C, Raheem D, Ramos F, Saraiva A, Raposo A. Microbial
biolms in the food industry—A comprehensive review. Int. J.
Environ. Res. Public Health. [Internet]. 2021; 18(4):2014. doi:
https://doi.org/gn9t4j
Escherichia coli associated with poultry farming / Saci et al. ________________________________________________________________________
10 of 10
[48] Di Martino G, Piccirillo A, Giacomelli M, Comin D, Gallina A, Capello
K, Buniolo F, Montesissa C, Bonfanti L. Microbiological, chemical
and physical quality of drinking water for commercial turkeys: a
cross–sectional study. Poult. Sci. [Internet]. 2018; 97(8):2880–
2886. doi: https://doi.org/gdd86h
[49] Augusto E, Aleixo J, Chilala FD, Chilundo AG, Gaspar B, Bila CG.
Physical, chemical and microbiological assessments of drinking
water of small–layer farms. Onderstepoort J. Vet. Res. [Internet].
2022; 89(1):a2067. doi: https://doi.org/mx22
[50] Awad AM, El–Shall NA, Khalil DS, El–Hack MEA, Swelum AA,
Mahmoud AH, Ebaid H, Komany A, Sammour RH, Sedeik ME.
Incidence, pathotyping, and antibiotic susceptibility of avian
pathogenic Escherichia coli among diseased broiler chicks.
Pathog. [Internet]. 2020; 9(2):114. doi: https://doi.org/mx23
