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. 2022 May 1;11(9):1324.
doi: 10.3390/foods11091324.

Characterization of Antibiotic Resistant Coliform Bacteria and Resistance Genes Isolated from Samples of Smoothie Drinks and Raw Milk

Monika Krahulcová  1 , Klára Cverenkárová  1 , Petra Olejníková  2 , Barbora Micajová  1 , Júlia Koreneková  1 , Lucia Bírošová  1
Affiliations

Characterization of Antibiotic Resistant Coliform Bacteria and Resistance Genes Isolated from Samples of Smoothie Drinks and Raw Milk

Monika Krahulcová et al. Foods. .

Abstract

Raw foodstuffs have been marked as a healthier alternative in the context of nutrient content and are becoming more popular with consumers. Thermally untreated foods may represent a microbiological risk connected with the possible presence of antimicrobial resistance. The aim of this study was to prove that popular raw food beverages such as smoothies and raw milk may be a source of antibiotic-resistant coliform bacteria and resistant genes. The majority of antibiotic-resistant isolates (110) were identified as Enterobacter spp., Escherichia coli, and species of Klebsiella spp., predominantly β-lactam and chloramphenicol resistant. Multidrug resistance has been registered in one-third of resistants. Overproduction of efflux pumps was clarified in 8 different bacteria. The majority of resistant isolates were strong biofilm producers. Antibiotic resistance gene blaOXA was detected in 25% of isolates, especially in E. coli. Resistance genes blaTEM and blaSHV were detected in 19% and 14%, respectively. This is the first study to point out that popular raw drinks such as smoothies or raw milk, besides their nutrient benefits, could represent a reservoir of antibiotic-resistant bacteria as well as antibiotic resistance genes. According to this, raw drinks could contribute to the dissemination of antibiotic resistance in the human gastrointestinal tract and environment.

Keywords: antibiotic resistance; coliform bacteria; raw milk; resistance genes; smoothie.

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Conflict of interest statement

The authors declare that there are no conflict of interest.

Figures

Figure 1
Figure 1
Number of identified resistant coliform bacteria isolated from samples of smoothie drinks (PO) and raw milk (AO).
Figure 2
Figure 2
Types of biofilm production of antibiotic-resistant isolates.
Figure 3
Figure 3
Distribution of detected resistance genes in different types of samples (smoothie drinks-PO and raw milk-AO).
See this image and copyright information in PMC

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