Molecular detection of enterotoxins in multidrug resistant Aeromonas from ready to eat foods in North Western Himalayas: Public health significance

Abstract

Aeromonas spp. are normal inhabitants of aquatic environments and are emerging foodborne bacterial pathogens. Aeromonas spp. contamination is frequent in ready-to-eat (RTE) seafood and can also occur in products prepared from milk or meat. The study determined the enterotoxin and antimicrobial susceptibility profiles of Aeromonas spp. isolates recovered from RTE milk products (n = 105), RTE meat/fish products (n = 40) and drinking water (n = 60) samples collected from tourist places in Himachal Pradesh, India, in northwestern Himalayas. 7.3 % (16/220) samples were found contaminated with Aeromonas spp. These isolates were identified as A. hydrophila (31.3 %), A. schubertii (25.0 %), A. sobria (25.0 %) and A. veronii (18.8 %). Aeromonas spp. contamination was significantly higher (14.3 %, 15/105, p = 0.0001) in RTE milk products. The contamination levels for water samples were 1.7 % whereas none of the tested RTE meat or fish products yielded Aeromonas spp. Among RTE milk products, contamination was significantly higher in paneer (South Asian soft cheese) (26.1 %, p = 0.0027) and cream (25.0 %, p = 0.046) based RTE foods. All isolates carried alt (361 bp), encoding a cytotonic heat-labile enterotoxin. Ampicillin resistance was 100 % and high levels (>30 %) of resistance were recorded for amoxicillin/clavulanic acid, amikacin, cefotaxime and ceftazidime. Six (37.5 %) isolates were multi drug resistant (MDR), showing resistance to aminoglycosides, cephams and penicillins. Isolation of alt carrying MDR isolates from RTE foods indicates that Aeromonas spp. can be potential foodborne public health threat in northwestern Himalayas.