Colistin Induces Resistance through Biofilm Formation, via Increased phoQ Expression, in Avian Pathogenic Escherichia coli

This study aimed to optimize the colistin-based antibacterial therapy to prevent antimicrobial resistance related to biofilm formation in avian pathogenic Escherichia coli (APEC) in chicken. Of all the bacterial isolates (n = 136), 69 were identified as APEC by polymerase chain reaction (PCR). Through a series of antibiotic susceptibility tests, susceptibility to colistin (<2 μg/mL) was confirmed in all isolates. Hence, a mutant selection window (MSW) was determined to obtain colistin-induced resistant bacteria. The minimum inhibitory concentration (MIC) of colistin against the colistin-induced resistant APEC strains ranged from 8 to 16 μg/mL. To identify the inhibitory activity of colistin against the resistant strains, the mutant prevention concentration (MPC) was investigated for 72 h, and the single and multi-dose colistin activities were determined through the time-kill curve against APEC strains. Bacterial regrowth occurred after 12 h at a double MIC50 concentration (1.00 μg/mL), and regrowth was not inhibited even during multiple exposures. However, upon exposure to 8 μg/mL—a concentration that was close to the MPC—the growth of APEC was inhibited, including in the resistant strains. Additionally, colistin-induced resistant strains showed a slower growth compared with the susceptible ones. Colistin-induced resistant APEC strains did not show colistin resistance gene (mcr-1). However, the expression of higher mgrB and phoQ levels was observed in the resistant strains. Furthermore, these strains showed increased formation of biofilm. Hence, the present study indicated that colistin could induce resistance through the increased formation of biofilm in APEC strains by enhancing the expression of phoQ.

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Evaluation of Fluoroquinolone Resistance in Clinical Avian Pathogenic Escherichia coli Isolates from Flanders (Belgium)

Antibiotics ◽

10.3390/antibiotics9110800 ◽

2020 ◽

Vol 9 (11) ◽

pp. 800

Author(s):

Robin Temmerman ◽

An Garmyn ◽

Gunther Antonissen ◽

Gerty Vanantwerpen ◽

Mia Vanrobaeys ◽

...

Keyword(s):

Escherichia Coli ◽

Rapid Development ◽

Fluoroquinolone Resistance ◽

Dilution Method ◽

Agar Dilution Method ◽

Avian Pathogenic Escherichia Coli ◽

Topoisomerase Iv ◽

Mutant Selection ◽

Pathogenic Escherichia Coli ◽

Mutant Prevention Concentration

Fluoroquinolones are frequently used antimicrobials for the treatment of avian pathogenic Escherichia coli (APEC) infections. However, rapid development and selection of resistance to this class of antimicrobial drugs is a significant problem. The aim of this study was to investigate the occurrence and mechanisms of antimicrobial resistance against enrofloxacin (ENRO) in APEC strains in Flanders, Belgium. One hundred and twenty-five APEC strains from broilers with clinical colibacillosis were collected in Flanders from November 2017 to June 2018. The minimum inhibitory concentration (MIC) of all strains and the mutant prevention concentration (MPC) of a sample of sensitive isolates were determined using a commercial gradient strip test and via the agar dilution method, respectively. Non-wild type (NWT) isolates were further characterized using polymerase chain reaction (PCR), gel electrophoresis and gene sequencing. Forty percent of the APEC strains were NWT according to the epidemiological cut-off (ECOFF) measure (MIC > 0.125 μg/mL). With respect to clinical breakpoints, 21% were clinically intermediate (0.5 ≤ MIC ≤ 1 μg/mL) and 10% were clinically resistant (MIC ≥ 2). The MPC values of the tested strains ranged from 0.064 to 1 μg/mL, resulting in MPC/MIC ratios varying from 4 to 32. The majority (92%) of the NWT strains carried one or two mutations in gyrA. Less than a quarter (22%) manifested amino acid substitutions in the topoisomerase IV parC subunit. Only three of the NWT strains carried a mutation in parE. Plasmid mediated quinolone resistance (PMQR) associated genes were detected in 18% of the NWT strains. In contrast to the relatively large number of NWT strains, only a small percentage of APEC isolates was considered clinically resistant. The most common MPC value for sensitive strains was 0.125 μg/mL. Some isolates showed higher values, producing wide mutant selection windows (MSW). Chromosomal mutations in DNA gyrase and topoisomerase IV were confirmed as the main source of decreased antimicrobial fluoroquinolone susceptibility, de-emphasizing the role of PMQR mechanisms.

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Biofilm Formation by Avian Pathogenic Escherichia coli is Not Related to In Vivo Pathogenicity

Current Microbiology ◽

10.1007/s00284-018-1608-8 ◽

2018 ◽

Vol 76 (2) ◽

pp. 194-199 ◽

Cited By ~ 1

Author(s):

Suelle V. Rodrigues ◽

Vanessa Laviniki ◽

Karen A. Borges ◽

Thales Q. Furian ◽

Hamilton L. S. Moraes ◽

...

Keyword(s):

Escherichia Coli ◽

Biofilm Formation ◽

Avian Pathogenic Escherichia Coli ◽

Pathogenic Escherichia Coli

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Characterization and antimicrobial resistance patterns of Escherichia coli isolated from feces of healthy broiler chickens

Arquivos do Instituto Biológico ◽

10.1590/1808-1657000392014 ◽

2016 ◽

Vol 83 (0) ◽

Cited By ~ 3

Author(s):

Ariel Eurides Stella ◽

Maria Cristina De Oliveira ◽

Vera Lúcia Dias da Silva Fontana ◽

Renato Paris Maluta ◽

Clarissa Araújo Borges ◽

...

Keyword(s):

Escherichia Coli ◽

Broiler Chickens ◽

Clinical Signs ◽

Avian Pathogenic Escherichia Coli ◽

E Coli ◽

The Past ◽

Pathogenic Escherichia Coli ◽

Resistance Patterns ◽

Resistant Strains ◽

Polymerase Chain

ABSTRACT: Avian pathogenic Escherichia coli (APEC) strains are isolated from lesions of poultry presenting colibacillosis, which is a disease that causes either systemic or localized clinical signs. Such strains share many characteristics with E. coli strains that cause extra-intestinal illness in humans. There is not a consensus on how to define the APEC pathotype with regard to the presence of virulence traits. On the other hand, in the past few years, five minimal predictors for APEC detection were proposed. The E. coli isolates in this work were tested through polymerase chain reaction (PCR) to the five proposed minimal predictors and cva C. The strains presenting them were categorized as potential APEC. The APEC and non-APEC categories showed high resistance (> 50%) to cephalotin, erythromycin, streptomycin, sulphametoxazol/trimethoprim, ampicillin, and amoxicillin. Potential APEC strains were significantly more resistant to cephalotin (p < 0.05) and neomcycin (p < 0.01) than non-APEC. These latter were significantly more resistant to tetracycline (p < 0.01) than the potential APEC strains. These results demonstrate that feces of poultry present E. coli strains with resistant features, showing or not the potential of causing colibacillosis in poultry. Because APEC and extra-intestinal illness in humans may be similar, these resistant strains are of interest to public health.

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