MICROBIAL PATHOGENESIS, cilt.196, sa.1670, ss.1-11, 2024 (SCI-Expanded)
The intensification of livestock farming has led to the widespread use of massive amounts of antibiotics
worldwide. Poultry production, including white meat, eggs and the use of their manure as fertiliser, has been
identified as one of the most crucial reservoirs for the emergence and spread of resistant bacteria, including E.
coli in poultry as an important opportunistic pathogen representing the greatest biological hazard to human and
wildlife health. Thus, this study aimed to analyse E. coli in the faecal carriage of healthy poultry flocks and to
investigate the phenotypic and genotypic characteristics of antimicrobial resistance, including integrons genes
and phylogenetic groups. A total of 431 cloacal swabs from apparently healthy poultry from four regions in
Eastern Algeria from December 2021 to October 2022. 360 E. coli were isolated; from broilers (n = 151), broiler
breeders (n = 91), laying hens (n = 72), and breeding hens (n = 46). Among this, 281 isolates exhibited
multidrug resistance (MDR) phenotype, 17 of the 360 E. coli isolates exhibited ESBL, and one isolate exhibited
both ESBL/pAmpC. A representative collection of 183 among 281 MDR E. coli was selected for further analysis by
PCR to detect genes encoding resistance to different antibiotics, and sequencing was performed on all positive
PCR products of blaCTX-M and blaCMY-2 genes. Phylogenetic groups were determined in 80 E. coli isolates (20 from
each of the four kinds of poultry). The blaCTX-M gene was found in 16 (94.11 %) ESBL-producing E. coli isolates
within 11 strains co-expressing the blaSHV gene and 8 strains co-expressing the blaTEM gene. Sequence analysis
showed frequent diversity in CTX-M-group-1, with blaCTX-M-15 being the most predominant (n = 11), followed by
blaCTX-M-1 (n = 5). The blaCMY-2 gene was detected only in one ESBL/pAmpC isolate. Among the 183 tested
isolates, various antimicrobial resistance genes were found (number of strains) blaTEM (n = 121), blaSHV (n = 12),
tetA (n = 100), tetB (n = 29), sul1(n = 67), sul2 (n = 32), qnrS (n = 45), qnrB (n = 10), qnrA (n = 1), catA1(n =
13), aac-(6′)-Ib (n = 3). Furthermore, class 1 and class 2 integrons were found in 113 and 2 E. coli, respectively.
The isolates were classified into multiple phylogroups, including A (35 %), B1 (27.5 %), B2 and D each (18.75
%). The detection of integrons and different classes of resistance genes in the faecal carriage of healthy poultry
production indicates that commensal E. coli could potentially act as a reservoir for antimicrobial resistance,
posing a significant One Health challenge encompassing the interconnected domains of human, animal health
and the environment. Here, we present the first investigation to describe the diversity of blaCTX-M producing E.
coli isolates with widespread detection of CTX-M-15 and CTX-M-1 in healthy breeders (Broiler and breeding
hens) in Eastern Algeria.