Streptococcus iniae biofilm formation enhances environmental persistence and resistance to antimicrobials and disinfectants

Heckman, Taylor I.; Soto, Esteban

doi:10.1016/j.aquaculture.2021.736739

Cited by 14 publications

(7 citation statements)

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“…Bacteria become more resistant to the same antibiotics when they are part of the biofilm, inhibiting the penetration of the antibiotics into the biofilm structure (Acharjee et al, 2021), which can slow the growth rate within the biofilm, resulting in a genetic selection of resistant strains (Costerton et al, 1999). Furthermore, Streptococcus iniae is already resistant to a wide range of antimicrobials, including FLO, when the bacterium is part of a biofilm (Heckman & Soto, 2021). Thus, the antimicrobials needed to eliminate cells within biofilms are 10-1000 times higher than planktonic bacteria (Sharma et al, 2019).…”

Section: Re Sults and Discussionmentioning

confidence: 99%

“…More interestingly, many P. salmonis isolates carry the plasmid p3PS10, which contains multidrug resistance genes for several antibiotics, exhibiting reduced susceptibility to oxytetracycline in vitro (Saavedra et al, 2018). Thus, bacteria living in a biofilms matrix can alter their metabolism and modify their gene expression to persist under several stressors or adverse conditions, including the presence of antibiotics (Olsen, 2015; Song et al, 2016), constituting a reservoir for future infections in aquaculture systems (Balcázar et al, 2015; De Carvalho, 2018; Heckman & Soto, 2021). In addition, antibiotics and disinfectants can also induce bacteria to produce biofilms (Ferrer et al, 2017; Kaplan, 2011; Penesyan et al, 2020; Uzunbayir‐Akel et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

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Subinhibitory concentrations of florfenicol increase the biofilm formation of Piscirickettsia salmonis

Oliver

Céspedes

Santibáñez

et al. 2023

Journal of Fish Diseases

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Piscirickettsia salmonis is a Gram-negative facultative intracellular γ-proteobacterium, classified into two genogroups: LF-89 T (ATCC VR-1361) and EM-90 strains (Nourdin-Galindo et al., 2017). This bacterium is the aetiological agent of piscirickettsiosis, a systemic fish disease characterized by the bacterial colonization of several organs, including liver, kidney, spleen, skeletal muscle, intestine and gills among others (Rozas & Enríquez, 2014), causing severe economic losses in Chilean salmonid farms (Sernapesca, 2022a). Although the main disease outbreaks and the subsequent associated mortality had been identified in southern Chile, this disease has also been reported in several countries (Rozas & Enríquez, 2014). The Chilean salmon industry uses several biosecurity measures as a way to mitigate the impact of infectious diseases. Thus, 29 different vaccine formulations are currently approved for use against piscirickettsiosis (SAG, 2022) Statistical data from The Chilean National Fisheries and Aquaculture Service (SERNAPESCA) indicated that piscirickettsiosis is the most prevalent bacterial disease affecting Chilean salmon (Sernapesca, 2022a). For this reason, antibiotics remain the primary treatment against piscirickettsiosis outbreaks. The Chilean salmon industry used 4634 tons of antibiotics in

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Section: Re Sults and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Subinhibitory concentrations of florfenicol increase the biofilm formation of Piscirickettsia salmonis

Oliver

Céspedes

Santibáñez

et al. 2023

Journal of Fish Diseases

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“…Soh et al ( 2020 ) reported two virulence factors of S. iniae , extracellular nuclease (SpnAi) and secreted nucleotidase (S5nAi), which play important roles in the immune escape of S. iniae . Besides, biofilms seem to play an important role in resisting the host's immune defenses during S. iniae infection (Heckman and Soto, 2021 ).…”

Section: Discussionmentioning

confidence: 99%

The Antibacterial Activity of Thymol Against Drug-Resistant Streptococcus iniae and Its Protective Effect on Channel Catfish (Ictalurus punctatus)

et al. 2022

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Streptococcus iniae is a zoonotic pathogen, which seriously threatens aquaculture and human health worldwide. Antibiotics are the preferred way to treat S. iniae infection. However, the unreasonable use of antibiotics leads to the enhancement of bacterial resistance, which is not conducive to the prevention and treatment of this disease. Therefore, it is urgent to find new efficient and environmentally friendly antibacterial agents to replace traditional antibiotics. In this study, the antibacterial activity and potential mechanism of thymol against S. iniae were evaluated by electron microscopy, lactate dehydrogenase, DNA and protein leakage and transcriptomic analysis. Thymol exhibited potent antibacterial activity against S. iniae in vitro, and the MIC and MBC were 128 and 256μg/mL, respectively. SEM and TEM images showed that the cell membrane and cell wall were damaged, and the cells were abnormally enlarged and divided. 2MIC thymol disrupted the integrity of cell walls and membranes, resulting in the release of intracellular macromolecules including nucleotides, proteins and inorganic ions. The results of transcriptomic analysis indicated that thymol interfered with energy metabolism and membrane transport, affected DNA replication, repair and transcription in S. iniae. In vivo studies showed that thymol had a protective effect on experimental S. iniae infection in channel catfish. It could reduce the cumulative mortality of channel catfish and the number of S. iniae colonization in tissues, and increase the activities of non-specific immune enzymes in serum, including catalase, superoxide dismutase, lysozyme and acid phosphatase. Taken together, these findings suggested that thymol may be a candidate plant agent to replace traditional antibiotics for the prevention and treatment of S. iniae infection.

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“…Recently, dietary intake of probiotics such as plant extracts, nutritional factors, polysaccharides, and cytokines has been reported to be effective immunostimulants in fish, although more in-depth species-specific studies are needed [ 47 ]. The use of commercial vaccines could be difficult because, although several formulations are available worldwide [ 12 , 31 , 47 , 48 ], these are not available in Italy. Another challenge in implementing a vaccination plan is the lack of cross-protection against the different S. iniae strains [ 12 ].…”

Section: Discussionmentioning

confidence: 99%

Mortality in farmed European eel (Anguilla anguilla) in Italy due to Streptococcus iniae

Pirollo

Perolo²,

Mantegari

et al. 2023

Acta Vet Scand

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Background Streptococcal infections are one of the main causes of fish disease. During the last decade, Streptococcus iniae has become one of the most important aquatic pathogens worldwide, causing high losses in marine and freshwater finfish. Clinical signs in farmed fish include loss of appetite, lethargy and grouping at the bottom of the tank. Gross changes comprise darkening of the skin and haemorrhage at the basis of fins and opercula. To date, S. iniae has been isolated from several wild and farmed fish species but never in the European eel (Anguilla anguilla). In Europe, eel production from aquaculture is around 4500 tonnes and Italy is the third largest producer. This communication represents the first report of an outbreak of S. iniae infection in European eels. Case presentation The outbreak occurred at an eel farm in northern Italy between May 2021 and September 2021. The outbreak caused about 2% mortality per month, resulting in the loss of about 10% of the farmed fish. The diseased eels showed apathy, lethargy, inactivity and inappetence. In July 2021, three eels were necropsied. Necropsy revealed skin and branchial hyperaemia, a few skin ulcers, and diffuse peritoneal congestion with a few haemorrhagic-like spot lesions. Swab samples for bacteriology were taken from the kidneys, liver, spleen, and brain. Additionally, four eels were opened and swap samples as above were taken. All the investigated eels were found dead. Bacteriological examination revealed growth of Streptococcus spp. from all samples. Identification of S. iniae was done by biochemical characterization, the API20STREP microsystem, 16S rDNA sequencing, and MALDI-TOF. Antimicrobial therapy (oxytetracycline and erythromycin) was ineffective. Conclusions This is the first report of S. iniae infection in the European eel. Although this may be an isolated outbreak, it is of concern due to the losses associated with this pathogen in fish worldwide and because the European eel is an endangered species. Due to the difficulties of controlling the disease with antimicrobials, it is advisable to plan other effective control measures, such as improving water quality and the environmental conditions, reducing fish density, improving biosecurity, and by using immunostimulants and, when possible, vaccines.

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Streptococcus iniae biofilm formation enhances environmental persistence and resistance to antimicrobials and disinfectants

Cited by 14 publications

References 57 publications

Subinhibitory concentrations of florfenicol increase the biofilm formation of Piscirickettsia salmonis

Subinhibitory concentrations of florfenicol increase the biofilm formation of Piscirickettsia salmonis

The Antibacterial Activity of Thymol Against Drug-Resistant Streptococcus iniae and Its Protective Effect on Channel Catfish (Ictalurus punctatus)

Mortality in farmed European eel (Anguilla anguilla) in Italy due to Streptococcus iniae

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