Emerging resistance to aminoglycosides in lactic acid bacteria of food origin—an impending menace

Aminoglycosides are the most preferred choice of
therapy against serious infections in humans. Therefore, its
use in animal husbandry has been strictly regulated in the EU,
UK, and USA to avoid the hazards of aminoglycoside resistance
in gut microflora. Nevertheless, aminoglycosides are recommended
for prophylaxis and therapeutics in food animals
and agriculture owing to its bactericidal nature. In the recent
past, the global surge in aminoglycoside-resistant lactic acid
bacteria (LAB) from food sources has been noticed that might
question its continued use in animal husbandry. Upon antibiotic
administration, a selective pressure is created in the gut environment;
in such instances, LAB could act as reservoirs of
antibiotic resistance which may facilitate their transfer to pathogenic
organisms contradicting its probiotic and industrial significance.
Thismay be a risk to human health as the presence of
one aminoglycoside resistance gene renders the bacteria tolerant
to almost all antibiotics of the same class, thereby challenging
its therapeutic efficacy. Low doses of aminoglycosides are
recommended in farm animals due to its toxic nature and insolubility
in blood. However, recent investigations indicate that
use of aminoglycosides in sub-lethal concentrations can trigger
the selection and conjugal transfer of aminoglycoside resistance
in probiotic LAB. Resistance to erythromycin, tetracyclines,
and fluoroquinolones in LAB were reported earlier to which
immediate regulatory measures were adopted by some countries.
Paradoxically, lack of regulations on antibiotic use in
farms in most developing countries makes them a potential
source of antibiotic resistance and its uncontrolled spread
around the globe. The prevalence of aminoglycoside resistance
was observed in enterococci from food origin earlier; however,
its emergence in lactobacilli and pediococci suggests its spread
in probiotic cultures which prompts immediate precautionary
methods. This review highlights the emergence and hazards of
aminoglycoside-resistant LAB which is in prime commercial
demand both for preparing fermented food and also pharmabased
therapeutics. It further focuses on the mode of aminoglycoside
resistance and its occurrence in food-grade LAB, thus
relating to its role in worldwide transfer via the food chain in
spite of its limited use as compared to other antibiotics.