Genetic relatedness and novel sequence types of clinical Aeromonas dhakensis from Malaysia

Lau, Tien Tien Vicky; Tan, Jin‐Ai Mary Anne; Puthucheary, S. D.; Puah, Suat Moi; Chua, Kek Heng

doi:10.1007/s42770-020-00239-8

Cited by 12 publications

(14 citation statements)

References 37 publications

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“…The genomes for the A. dhakensis ST656 isolates generated in this present study are the first to be reported from striped catfish and are a welcome supplement to the relatively few genomes available for this species, compared to A. hydrophila . However, A. dhakensis is attracting increasing attention as an emerging pathogen with zoonotic potential, especially in Asia, where this species has been associated with serious infections and fatalities in humans (Huys et al, 2002 ; Wu et al, 2012 ; Chen et al, 2016 ; Khor et al, 2018 ; Kitagawa et al, 2019 ; Lau et al, 2020 ; Sun et al, 2021 ). Interestingly, though ST656 has been recovered exclusively so far from fish hosts, this clone was placed within a larger clonal complex of A. dhakensis strains originating from human clinical cases ( Figure 3 ), meaning outbreaks of disease due to A. dhakensis in fish hosts present a theoretical risk to susceptible individuals interacting with infected stocks.…”

Section: Discussionmentioning

confidence: 99%

Aeromonas hydrophila ST251 and Aeromonas dhakensis are major emerging pathogens of striped catfish in Vietnam

Bartie

Ngo²,

Bekaert

et al. 2023

Front. Microbiol.

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IntroductionAeromonads are ubiquitous in aquatic environments and several species are opportunistic pathogens of fish. Disease losses caused by motile Aeromonas species, particularly Aeromonas hydrophila, can be challenging in intensive aquaculture, such as at striped catfish (Pangasianodon hypophthalmus) farms in Vietnam. Outbreaks require antibiotic treatments, but their application is undesirable due to risks posed by resistance. Vaccines are an attractive prophylactic and they must protect against the prevalent strains responsible for ongoing outbreaks.MethodsThis present study aimed to characterize A. hydrophila strains associated with mortalities in striped catfish culture in the Mekong Delta by a polyphasic genotyping approach, with a view to developing more effective vaccines.ResultsDuring 2013–2019, 345 presumptive Aeromonas spp. isolates were collected at farms in eight provinces. Repetitive element sequence-based PCR, multi-locus sequence typing and whole-genome sequencing revealed most of the suspected 202 A. hydrophila isolates to belong to ST656 (n = 151), which corresponds to the closely-related species Aeromonas dhakensis, with a lesser proportion belonging to ST251 (n = 51), a hypervirulent lineage (vAh) of A. hydrophila already causing concern in global aquaculture. The A. dhakensis ST656 and vAh ST251 isolates from outbreaks possessed unique gene sets compared to published A. dhakensis and vAh ST251 genomes, including antibiotic-resistance genes. The sharing of resistance determinants to sulphonamides (sul1) and trimethoprim (dfrA1) suggests similar selection pressures acting on A. dhakensis ST656 and vAh ST251 lineages. The earliest isolate (a vAh ST251 from 2013) lacked most resistance genes, suggesting relatively recent acquisition and selection, and this underscores the need to reduce antibiotics use where possible to prolong their effectiveness. A novel PCR assay was designed and validated to distinguish A. dhakensis and vAh ST251 strains.DiscussionThis present study highlights for the first time A. dhakensis, a zoonotic species that can cause fatal human infection, to be an emerging pathogen in aquaculture in Vietnam, with widespread distribution in recent outbreaks of motile Aeromonas septicaemia in striped catfish. It also confirms vAh ST251 to have been present in the Mekong Delta since at least 2013. Appropriate isolates of A. dhakensis and vAh should be included in vaccines to prevent outbreaks and reduce the threat posed by antibiotic resistance.

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Section: Discussionmentioning

confidence: 99%

Aeromonas hydrophila ST251 and Aeromonas dhakensis are major emerging pathogens of striped catfish in Vietnam

Bartie

Ngo²,

Bekaert

et al. 2023

Front. Microbiol.

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“…A total of 117 A. dhakensis isolates were retrieved from previous studies [ 7 , 8 , 9 , 10 , 11 , 12 , 22 ]. These isolates consisted of 94 clinical isolates from Malaysia and Singapore and 23 non-clinical isolates from Malaysia ( Table 4 ).…”

Section: Methodsmentioning

confidence: 99%

“…A. dhakensis has been misidentified as A. hydrophila or A. caviae by phenotypic methods in the past decade. Our previous studies conducted since 2012 identified A. dhakensis as the predominant species (47/94, 50%) among clinical isolates in Malaysia by using a combination gene analysis of GCAT and rpoD genes, as well as multilocus sequence typing [ 7 , 8 ]. Following these studies, the presence of A. dhakensis was reported from aquatic sources in Malaysia, including multipurpose freshwater recreational lakes in Selangor [ 9 ], tank water of ornamental fish in Klang Valley [ 10 ], food fish in East Malaysia [ 11 ] and as clinical isolates of A. dhakensis in Singapore [ 12 ].…”

Section: Introductionmentioning

confidence: 99%

Aeromonas dhakensis: Clinical Isolates with High Carbapenem Resistance

Puah

Khor²,

Aung³

et al. 2022

Pathogens

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Aeromonas dhakensis is ubiquitous in aquatic habitats and can cause life-threatening septicaemia in humans. However, limited data are available on their antimicrobial susceptibility testing (AST) profiles. Hence, we aimed to examine their AST patterns using clinical (n = 94) and non-clinical (n = 23) isolates with dehydrated MicroScan microdilution. Carbapenem resistant isolates were further screened for genes related to carbapenem resistance using molecular assay. The isolates exhibited resistance to imipenem (76.9%), doripenem (62.4%), meropenem (41.9%), trimethoprim/sulfamethoxazole (11.1%), cefotaxime (8.5%), ceftazidime (6%), cefepime (1.7%) and aztreonam (0.9%), whereas all isolates were susceptible to amikacin. Clinical isolates showed significant association with resistance to doripenem, imipenem and meropenem compared to non-clinical isolates. These blacphA were detected in clinical isolates with resistance phenotypes: doripenem (67.2%, 45/67), imipenem (65.9%, 54/82) and meropenem (65.2%, 30/46). Our findings showed that the MicroScan microdilution method is suitable for the detection of carbapenem resistance in both clinical (48.9–87.2%) and non-clinical (4.3–13.0%) isolates. This study revealed that A. dhakensis isolates had relatively high carbapenem resistance, which may lead to potential treatment failure. Continued monitoring of aquatic sources with a larger sample size should be carried out to provide further insights.

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“…The sequence identity matrix analysis was performed with BioLign software ver. 4.0.6.2 ( Lau et al, 2020 ).…”

Section: Methodsmentioning

confidence: 99%

Plant Growth and Drought Tolerance-Promoting Bacterium for Bioremediation of Paraquat Pesticide Residues in Agriculture Soils

et al. 2021

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Thailand is an agricultural country. However, agricultural productivity relies on the heavy use of herbicides, especially paraquat. Paraquat accumulation is emerging as a problem in an ever-growing portion of agricultural land. Paraquat residues are toxic to plants, animals, and aquatic organisms in the environment. Biological remediation is a process that can mitigate agricultural chemical contaminants. One of the interesting bioremediators is bacteria. Not only do certain soil bacteria remediate paraquat, but some of them also possess plant growth-promoting properties, which provide advantages in field application. Thus, this study aimed to screen soil bacteria that could degrade paraquat and, at the same time, promote plant growth. Bacteria were isolated from paraquat-treated agricultural soil in Mueang Kaen Pattana municipality, Chiang Mai province, Thailand. On the basis of morphological and 16S rDNA sequence analyses, the selected bacterium was identified as Bacillus aryabhattai strain MoB09. It is capable of growing in nitrogen-free media. B. aryabhattai growth and paraquat degradation were found to be optimum at pH 7 and 30°C. This selected strain also possessed plant growth-promoting abilities, including indole production, siderophore production, phosphate solubilization, and 1-aminocyclopropane-1-carboxylic acid deaminase activity. Paraquat degradation was also evaluated in pot experiments of cowpea (Vigna unguiculata). It was found that this strain could remediate the paraquat residue in both sterilized and non-sterilized soils. The cowpea plants grown in paraquat-contaminated soil with B. aryabhattai showed longer root and shoot lengths than those grown in soil without bacterial inoculation. In addition, B. aryabhattai also promoted the growth of cowpea under induced drought stress. These results suggested that B. aryabhattai could be applied to mitigate paraquat residue in soil and also to promote plant productivity for the organic crop production.

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Genetic relatedness and novel sequence types of clinical Aeromonas dhakensis from Malaysia

Cited by 12 publications

References 37 publications

Aeromonas hydrophila ST251 and Aeromonas dhakensis are major emerging pathogens of striped catfish in Vietnam

Aeromonas hydrophila ST251 and Aeromonas dhakensis are major emerging pathogens of striped catfish in Vietnam

Aeromonas dhakensis: Clinical Isolates with High Carbapenem Resistance

Plant Growth and Drought Tolerance-Promoting Bacterium for Bioremediation of Paraquat Pesticide Residues in Agriculture Soils

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