Aeromonas aquariorum sp. nov., isolated from aquaria of ornamental fish

Abstract

During a survey to determine the prevalence of Aeromonas strains in water and skin of imported ornamental fish, 48 strains presumptively identified as Aeromonas were isolated but they could not be identified as members of any previously described Aeromonas species. These strains were subjected to a polyphasic approach including phylogenetic analysis derived from gyrB, rpoD and 16S rRNA gene sequencing, DNA-DNA hybridization, MALDI-TOF MS analysis, genotyping by RAPD and extensive biochemical and antibiotic susceptibility tests in order to determine their taxonomic position. Based on the results of the phylogenetic analyses and DNA-DNA hybridization data, we describe a novel species of the genus Aeromonas, for which the name Aeromonas aquariorum sp. nov. is proposed, with strain MDC47 T (5DSM 18362 T 5CECT 7289 T ) as the type strain. This is the first Aeromonas species description based on isolations from ornamental fish.Species of Aeromonas are common inhabitants of aquatic environments and have been described in connection with fish and human diseases (Altwegg, 1999;Austin & Adams, 1996;Saavedra et al., 2004;Figueras, 2005). Apart from the psychrophilic suspected fish pathogen Aeromonas salmonicida, many other mesophilic aeromonads are considered to be opportunistic pathogens, capable of producing infections in weakened fish or as secondary invaders in fish populations suffering from other diseases (Camus et al., 1998). Given the large numbers of ornamental fish imported from areas of the world where sanitation is often inadequate and where numerous diseases of man are endemic, it is surprising that little consideration has been given to the role of these aquarium species as vectors of potential pathogens for man. When the occurrence of bacterial pathogens in ornamental fish has been investigated, Aeromonas strains were found in more than 50 % of fish disease cases examined by Kuo & Chung (1994) and were involved in 18 of 23 bacterial disease outbreaks investigated by Hettiarachchi & Cheong (1994). Moreover, noticeable antibiotic resistance has been detected in Aeromonas strains isolated from ornamental fish (Dixon & Issvoran, 1992).The genus Aeromonas belongs to the family Aeromonadaceae (Colwell et al., 1986;Martínez-Murcia et al., 1992a; Yáñez et al., 2003). According to the last edition of Bergey's Manual of Systematic Bacteriology (Martin-Carnahan & Joseph, 2005), the genus comprises the species Aeromonas hydrophila, A. bestiarum, A. salmonicida, A. caviae, A. media, A. eucrenophila, A. sobria, A. veronii (biovars Sobria and Veronii), A. jandaei, A. schubertii, A. trota, A. allosaccharophila, A. encheleia and A. popoffii and two DNA homology groups, Aeromonas sp. HG11 and Aeromonas sp. HG13 (formerly enteric group 501), which remain without a species name. Furthermore, Aeromonas ichthiosmia (Schubert et al., 1990b) and Aeromonas enteropelogenes (Schubert et al., 1990a) are now considered synonyms of A. veronii and A. trota, respectively (Carnahan, 1993;Collins et al., 1993;Huys et al., 2001Huys et al., ,...

Antimicrobial Resistance Patterns of Aeromonas spp. Isolated from Ornamental Fish

“…This fact might suggest that this specie is not frequent in ornamental fish infections, as previously reported on South African ornamental fish [32]. Mesophilic aeromonads are considered to be opportunistic pathogens, capable of producing infections in weakened fish or as secondary invaders in fish populations suffering from others diseases [15,33].…”

“…Bacteria strains were identified, following standard procedures, to identify Aeromonas at the genus level, and further standard biochemical classification was performed by using API 50 CH (bioMérieux) at 30°C for 48 h, following the manufacturer's instructions. Procedures and characteristics of oligonucleotide primers for amplification and PCR-based sequencing house-keeping genes (gyrB and rpoD) are as described previously [15]. PCR products were purified with QIAquick PCR purification kit (QIAGEN, Germany), following the manufacturer`s instructions and prepared for sequencing by using the Big Dye Terminator V.3.1 cycle sequencing kit and amplified genes were sequenced with an ABI PRISM 3100 Genetic Analyser (Applied Biosystems, USA).…”

Distribution and phenotypic and genotypic detection of a metallo-β-lactamase, CphA, among bacteraemic Aeromonas isolates

“…For example, several clinical isolates from Taiwan were identified as A. aquariorum ), a recently described species found in aquarium water and ornamental fish (Martínez-Murcia et al, 2008). Furthermore, A. aquariorum was found to be widely distributed in clinical and environmental specimens, and could be misidentified as A. hydrophila (Aravena-Román et al, 2011).…”

Population Genetics of the “Aeromonas hydrophila Species Complex”

“…bestiarum, A. popoffii and A. salmonicida (Miñana-Galbis et al, 2002;Martin-Carnahan & Joseph, 2005). Recently, two additional species have been described in this group, A. aquariorum and A. piscicola (Martínez-Murcia et al, 2008;Beaz-Hidalgo et al, 2009). Members of the AHC were first described as strains producing the enzymes elastase, lecitinase or stapholysin (Abbott et al, 2003).…”

“…Several approaches have been used to discriminate among the AHC species: Amplified Fragment Length Polymorphisms (AFLP) (Huys et al, 1997), fluorescent AFLP (FAFLP) (Huys et al, 2002), MLEE (Miñana-Galbis et al, 2004), Random Amplified Polymorphic DNA (RAPD) and MALDI-TOF MS analysis (Martínez-Murcia et al, 2008). Although the results obtained with these methods have been useful for the taxonomy and phylogeny of the AHC, providing a hypothesis for the genealogy of strains and detailing their patterns of descent and degree of genetic variation accumulated over time, only the MLEE study has been used to elucidate their population genetic structure.…”