Prevalence, Identification and Antibiotic Resistance of Gallibacterium anatis Isolates from Chickens in Poland

Abstract

The Gram-negative bacterium Gallibacterium anatis is part of the normal avian respiratory, intestinal and reproductive tract microflora and can be transmitted horizontally and vertically. With the coexistence of other relevant factors, G. anatis becomes an opportunistic pathogen, economically damaging to the poultry industry. This bacterium’s prevalence and molecular epidemiology were investigated, and the antimicrobial treatment options for G. anatis infection in chicken flocks in Poland were assessed. Tracheal samples from 182 flocks were collected between April 2022 and March 2023. The bacterial prevalence was determined by PCR targeting the gyrB gene and 16–23S rRNA. Gallibacterium anatis was identified by matrix-assisted laser desorption/ionisation–time-of-flight mass spectrometry (MALDI-TOF) after culturing and PCR amplification. Isolates’ susceptibility to 11 antimicrobials was assessed with a disc diffusion test. Isolates were also tested for gyrB, GtxA and flfA virulence genes and blaROB, aphA, tetB and tetH antibiotic resistance genes by PCR. Forty-one flocks (22.5%) were positive through PCR. Antibiotic resistance was most frequently observed against tilmicosin, tylosin, enrofloxacin, amoxicillin, tetracycline and doxycycline. Multiple resistance to at least eight antibiotics occurred in 20% of isolates and to at least four in 100%. The occurrence of gyrB was noted in 100%, GtxA was detected in 89%, and flfA was found in 14% of positive samples. The tetB gene was present in 61.0% of positive samples, tetH was in 36.0%, aphA was in 16.7%, and blaROB was in 5.6%. Significant differences were found in G. anatis isolates related to the presence of the virulence genes GtxA and gyrB and the presence of resistance genes (p < 0.05) associated with resistance to tetracyclines, β-lactams and aminoglycosides. The continued rise in the resistance of G. anatis to a broadening range of antibiotics is a major problem for the poultry industry worldwide, as well as for public health. The findings of this study may expand the knowledge of the pathogenicity of G. anatis in poultry.

Antibiotic resistance of Gallibacterium anatis biovar haemolytica isolates from chickens

“…Our results are in agreement with the results of other authors (1,14,29). Isolates from our collection also showed high resistance to tetracycline (96.2%), tigecycline (57.7%) and doxycycline (46%), proving similar to resistance noted in previous studies (1,14,15,21). In addition, high resistance was evident to gentamicin (69.2%), an antibiotic of the aminoglycoside class.…”

“…Environmental factors that can affect the development of infection are seasonal changes or cold stress (10,22,25). Many reports inform of an increase of antibiotic resistance among G. anatis isolates (8,17,21,35). In our study, we used G. anatis biovar haemolytica strains isolated from three chicken anatomical tracts.…”

“…Specific primers designed to detect the 16–23S ribosomal RNA (rRNA) region were used. The mixture and the conditions described earlier were used for the reaction ( 21 ). The PCR amplicons were separated by electrophoresis on a 2% agarose E-gel plate (Invitrogen, Carlsbad, CA, USA) containing ethidium bromide, and were visualised by ultraviolet transillumination.…”

“…Multidrug resistance of bacteria is a growing problem for the poultry industry as well as for public health (1,2,17,19,31,35). Recent studies show common resistance in a large number of G. anatis strains to erythromycin and tylosin antibiotics from the macrolide class as well as antibiotics from the tetracycline class (2,8,17,21,31,35).…”