Prevalence and Persistence of Multidrug-Resistant Yersinia enterocolitica 4/O:3 in Tonsils of Slaughter Pigs from Different Housing Systems in Croatia
Journal
Foods
Date Issued
2022-05-18
Author(s)
Nevijo Zdolec; Marta Kiš; Dean Jankuloski; Katerina Blagoevska; Snježana Kazazić; Marina Pavlak; Bojan Blagojević; Dragan Antić; Maria Fredriksson-Ahomaa; Valerij Pažin
DOI
doi.org/10.3390/foods11101459
Abstract
Yersinia enterocolitica is one of the priority biological hazards in pork inspection. Persistence
of the pathogen, including strains resistant to antimicrobials, should be evaluated in pigs from
different housing systems for risk ranking of farms. In this 2019 study, tonsils were collected from
234 pigs, of which 69 (29.5%) were fattened on 3 big integrated farms, 130 (55.5%) on 10 medium-sized
farms, and 35 (15%) on 13 small family farms. In addition, 92 pork cuts and minced meat samples from
the same farms were tested for the presence of Y. enterocolitica using the culture method. Phenotypic
and genetic characteristics of the isolates were compared with previously collected isolates from
2014. The overall prevalence of Y. enterocolitica in pig tonsils was 43% [95% CI 36.7–49.7]. In pigs
from big integrated, medium-sized, and small family farms, the prevalence was 29%, 52%, and
40%, respectively. All retail samples of portioned and minced pork tested negative for pathogenic Y.
enterocolitica, likely due to high hygienic standards in slaughterhouses/cutting meat or low sensitivity
of culture methods in these matrices. The highest recovery rate of the pathogen from tonsils was
found when alkali-treated PSB and CIN agar were combined. The biosecurity category of integrated
and medium farms did not affect the differences in prevalence of Y. enterocolitica (p > 0.05), in contrast
to family farms. Pathogenic ail-positive Y. enterocolitica biotype 4 serotype O:3 persisted in the tonsils
of pigs regardless of the type of farm, slaughterhouse, and year of isolation 2014 and 2019. PFGE
typing revealed the high genetic concordance (80.6 to 100%) of all the Y. enterocolitica 4/O:3 isolates.
A statistically significant higher prevalence of multidrug-resistant Y. enterocolitica 4/O:3 isolates was
detected in the tonsils of pigs from big integrated farms compared to the other farm types (p < 0.05),
with predominant and increasing resistance to nalidixic acid, chloramphenicol, and streptomycin.
This study demonstrated multidrug resistance of the pathogen in pigs likely due to more antimicrobial
pressure on big farms, with intriguing resistance to some clinically relevant antimicrobials used in
the treatment of yersiniosis in humans.
of the pathogen, including strains resistant to antimicrobials, should be evaluated in pigs from
different housing systems for risk ranking of farms. In this 2019 study, tonsils were collected from
234 pigs, of which 69 (29.5%) were fattened on 3 big integrated farms, 130 (55.5%) on 10 medium-sized
farms, and 35 (15%) on 13 small family farms. In addition, 92 pork cuts and minced meat samples from
the same farms were tested for the presence of Y. enterocolitica using the culture method. Phenotypic
and genetic characteristics of the isolates were compared with previously collected isolates from
2014. The overall prevalence of Y. enterocolitica in pig tonsils was 43% [95% CI 36.7–49.7]. In pigs
from big integrated, medium-sized, and small family farms, the prevalence was 29%, 52%, and
40%, respectively. All retail samples of portioned and minced pork tested negative for pathogenic Y.
enterocolitica, likely due to high hygienic standards in slaughterhouses/cutting meat or low sensitivity
of culture methods in these matrices. The highest recovery rate of the pathogen from tonsils was
found when alkali-treated PSB and CIN agar were combined. The biosecurity category of integrated
and medium farms did not affect the differences in prevalence of Y. enterocolitica (p > 0.05), in contrast
to family farms. Pathogenic ail-positive Y. enterocolitica biotype 4 serotype O:3 persisted in the tonsils
of pigs regardless of the type of farm, slaughterhouse, and year of isolation 2014 and 2019. PFGE
typing revealed the high genetic concordance (80.6 to 100%) of all the Y. enterocolitica 4/O:3 isolates.
A statistically significant higher prevalence of multidrug-resistant Y. enterocolitica 4/O:3 isolates was
detected in the tonsils of pigs from big integrated farms compared to the other farm types (p < 0.05),
with predominant and increasing resistance to nalidixic acid, chloramphenicol, and streptomycin.
This study demonstrated multidrug resistance of the pathogen in pigs likely due to more antimicrobial
pressure on big farms, with intriguing resistance to some clinically relevant antimicrobials used in
the treatment of yersiniosis in humans.
Subjects
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