Aeromonas spp. simultaneously harbouring blaCTX-M-15, blaSHV-12, blaPER-1 and blaFOX-2, in wild-growing Mediterranean mussel (Mytilus galloprovincialis) from Adriatic Sea, Croatia

• Published in: International journal of food microbiology Vol. 166; no. 2; pp. 301 - 308
• Main Authors: Maravić, Ana, Skočibušić, Mirjana, Šamanić, Ivica, Fredotović, Željana, Cvjetan, Svjetlana, Jutronić, Marinka, Puizina, Jasna
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 02.09.2013; Elsevier
• Subjects: Aeromonads; Aeromonas caviae; Aeromonas hydrophila; AmpC β-lactamase; Antibiotic resistance; Biological and medical sciences; ESBL; Fish and seafood industries; Food industries; Food microbiology; Fundamental and applied biological sciences. Psychology; Marine; Marine environment; Mussels; Mytilus galloprovincialis; Mediterranean Sea; Adriatic Sea; Europe; Croatia; MED, Adriatic Sea; MED, Croatia; Marine environment; ESBL; Aeromonads; Mussels; AmpC β-lactamase; Antibiotic resistance; Edible mollusc; Shellfish; Mussel; Enzyme; Aeromonas; β-Lactamase; Mytilus galloprovincialis; Resistance; Antibiotic; Bivalvia; Bacteria; Hydrolases; Vibrionaceae; Invertebrata; Mollusca
• ISSN: 0168-1605; 1879-3460
• DOI: 10.1016/j.ijfoodmicro.2013.07.010

Aeromonas species are becoming renowned as emerging pathogens by increasingly giving rise to a wide spectrum of food and waterborne infections in humans. Another worrisome feature of aeromonads is the growing frequency of antibiotic resistance as a consequence of their prominent diversity in terms of resistance determinants. This study aimed at determining the antimicrobial resistance pattern, prevalence and characterization of acquired β-lactamases, including extended-spectrum-β-lactamases (ESBLs) and AmpC cephalosporinases, as well as the presence of class 1 and 2 integrons, in Aeromonas isolates from wild-growing Mediterranean mussel (Mytilus galloprovincialis) of the eastern coast of Adriatic Sea, Croatia. Isolates were tested for susceptibility to 16 antibiotics and β-lactam/β-lactamase inhibitor combinations. Cephalosporin-resistant isolates were further screened by PCR for genes encoding AmpC (blaFOX, blaCMY, blaMOX, blaLAT, blaBIL, blaDHA, blaACC, blaMIR, blaACT), ESBLs (blaTEM, blaSHV, blaCTX-M, blaPER, blaVEB, blaGES/IBC, blaOXA) and integrases (intI1, intI2, intI3). Location of bla genes was characterized by plasmid DNA fingerprinting and Southern blot hybridization. Plasmids carrying ESBL genes were investigated for transferability by conjugation and PCR-based replicon typed. Out of 147 Aeromonas isolates recovered, 30 (20%) demonstrated multiple resistance profile, with co-resistance most frequently detected against penicillins, piperacillin/sulbactam and tetracycline. ESBL-encoding genes were detected in 21 (13 Aeromonas caviae and 8 Aeromonas hydrophila) isolates, with blaCTX-M-15 gene identified in 19 and blaSHV-12 in 12 isolates. Among them, 10 isolates simultaneously harboured blaCTX-M-15 and blaSHV-12, while 3 isolates additionally carried an AmpC β-lactamase blaFOX-2 gene. blaPER-1 gene was identified in a single isolate also harbouring the blaCTX-M-15 gene. While blaSHV-12 was chromosomally encoded, blaCTX-M-15 was located on conjugative IncFIB-type plasmids of ~40kb in A. caviae isolates. IntI1 and intI2 genes were detected in 57.1% and 33.3% of ESBL-producing isolates. To the best our knowledge, this is the first report of environmental A. caviae isolates producing CTX-M-15, and isolation of SHV-12-producing A. hydrophila and A. caviae strains worldwide. This is also believed to be the first report of the FOX-2, CTX-M-15 and SHV-12 simultaneous production in aeromonads, highlighting both the potential risk for human health, and a role of these foodborne pathogens as reservoirs of resistance determinants in coastal marine environment. •Wild-growing mussels (M. galloprovincialis) are vehicles for ESBL-producing Aeromonas.•First report on environmental A. caviae isolates producing CTX-M-15.•First report on A. hydrophila and A. caviae producing SHV-12.•First report of FOX-2, CTX-M-15 and SHV-12 co-production in Aeromonas.