Susceptibility of Avian PathogenicEscherichia colifrom Laying Hens in Belgium to Antibiotics and Disinfectants and Integron Prevalence

Abstract

Avian pathogenic Escherichia coli (APEC) causes huge annual losses in the poultry industry worldwide. Multiresistance against antibiotics of APEC strains is increasingly seen in broilers, although much is still unknown about strains from laying hens where use of antibiotics is limited. Disinfection can reduce the infection burden. However, little is known about the presence of resistance against these products. Ninety-seven APEC strains were isolated from Belgian laying hens. The resistance to different classes of antibiotics was determined as well as the minimum inhibitory concentrations (MIC; agar and broth dilution) and minimum bactericidal concentrations (MBC) of five disinfectants most often used in the poultry industry (formaldehyde, glutaraldehyde, glyoxal, hydrogen peroxide, and a quaternary ammonium compound). The presence of integrons was determined by PCR Resistance to ampicillin (35.1%), nalidixic acid (38.1%), sulfonamides (SULFA, 41.2%), and tetracycline (TET, 53.6%) was high but resistance to other tested antibiotics was low. Nevertheless, two extended spectrum beta-lactamase producers were found. The MIC of the disinfectants for the APEC strains showed a Gaussian distribution, indicating that there was no acquired resistance. MBCs were similar to MICs via the broth dilution method, showing the bactericidal effect of the disinfectants. Twenty-one strains (21.6%) were found positive for class 1 integrons and a positive association between integron presence and resistance to trimethoprim, SULFA, and TET was found. No association could be found between integron presence and phylogenetic group affiliation. Susceptibility of APEC strains from laying hens to antibiotics is, in general, very high. Phenotypic resistance to commonly used disinfectants could not be found, indicating that the current use of disinfectants in the laying hen industry did not select for resistance.

Genetic elements associated with antimicrobial resistance among avian pathogenic Escherichia coli

“…In the present study, the proportion of integron carriage among APEC isolates is consistent with previous studies worldwide [10, 27]. In a study conducted in Egypt on APEC isolated from septicemic broilers, higher prevalence was reported for class 1 and 2 (46.6 and 9.6%, respectively) [5].…”

Presence of antimicrobial resistance in coliform bacteria from hatching broiler eggs with emphasis on ESBL/AmpC-producing bacteria

“…The distribution of the MIC values for H2O2 showed a bimodal distribution with the majority of isolates showing MIC values of 32-64 µg mL -1 and 3 isolates showing a MIC value of 2 µg mL -1 (Figure 1 B).Considering previously published data(Oosterik et al, 2014), the isolates showing MIC values of 32-64 µg mL -1 are probably wild type strains, while the isolates showing a MIC value of 2 µg mL -1 are probably isolates with increased susceptibility. It was therefore concluded that there was no acquired resistance towards both glutaraldehyde and H2O2.…”

“…The ranges of MIC values of the retrieved isolates and quality control strains were similar to MIC ranges described earlier (Oosterik et al, 2014). Since no wild type cut-off values are yet available for disinfectants, acquired resistance was assumed when MIC values showed a bimodal, multimodal or tailing distribution.…”

“…The MICs for all obtained isolates were determined with the broth microdilution assay according to the CLSI standards (2013), as previously described (Oosterik et al, 2014).…”

Quinolone-resistant Escherichia coli in Poultry Farming

“…Resistance to ciprofloxacin in E. coli strains isolated from turkeys ranging from 22% to 61% were also demonstrated in a 2012 UK study by Gosling et al (30). In lying hens in Belgium, the level of resistance to nalidixic acid was 38% (31).…”