The in‐vitro antibacterial effects of organic salts, chemical disinfectants and antibiotics against pathogens of black disease in fairy shrimp of Thailand

Abstract

The antibacterial effects of organic salts, chemical disinfectants and antibiotics were evaluated on cultures of Aeromonas hydrophila C03, Aeromonas sobria C26, A. sobria C29, Aeromonas caviae C24 and Acinetobacter sp. SH-94B, the pathogens that cause black disease found in fairy shrimps (Streptocephalus sirindhornae Sanoamuang et al. (2000) and Branchinella thailandensis Sanoamuang, Saengphan & Murugan) of Thailand. The minimal inhibitory concentrations (MICs) of organic salts (sodium chloride and potassium chloride) and antibiotics (oxytetracycline dihydrate, streptomycin sulphate, kanamycin monosulphate, chloramphenicol and ampicillin) were determined using the agar-dilution method. The effect of chemical disinfectants (sodium hypochlorite and chlorine dioxide) was evaluated by exposing bacteria to different concentrations of these chemicals for different periods of time. Interestingly, all strains were intrinsically resistant to 0.25-3% sodium chloride and potassium chloride. The effect of sodium hypochlorite was greater than that of chlorine dioxide, and 5-20 μg mL(-1) of sodium hypochlorite was sufficient to inhibit the growth of these bacteria, but the exposure time varied, depending on the bacterial species. Of the antibiotics tested, chloramphenicol and oxytetracycline dihydrate completely inhibited the selected strains. Chloramphenicol showed the highest antibacterial effect against all pathogenic species--the MIC and minimal bactericidal concentration (MBC) ranged from 0.8 to 3.1 μg mL(-1) from 3.1 to 6.25 μg mL(-1), respectively. To achieve control of black disease during cultivation of fairy shrimp, data derived from this study can be used as a basis for further toxicity tests in vivo.

The in vitro efficacy of oxytetracycline against re-isolated pathogenicAeromonas hydrophilacarrying the cytolytic enterotoxin gene through hybrid catfish,Clarias macrocephalus(Günther, 1864) ×Clarias gariepinus(Burchell, 1822) in Thailand

“…Based on MBC determination, a concentration of 1-8 lg/ml was investigated against the five clinical strains under study ( Table 2). The results were comparable to those reported by Saejung, Hatai and Sanoamuang (2014) in diseased fairy shrimps (Streptocephalus sirindhornae)…”

“…Based on MBC determination, a concentration of 1–8 μg/ml was investigated against the five clinical strains under study (Table ). The results were comparable to those reported by Saejung, Hatai and Sanoamuang () in diseased fairy shrimps ( Streptocephalus sirindhornae ) with MBC values of about 3.1–6.25 μg/ml. It is not only oxytetracycline, which is effective against Aeromonas strains but also other antibiotics of this family.…”

BALOs Improved Gut Microbiota Health in Postlarval Shrimp (Litopenaeus vannamei) After Being Subjected to Salinity Reduction Treatment

“…Additionally, traditional ecological theory reminds us that such monopoly dominance by one class/genus could render an ecosystem in an extremely unstable state and prone to pathogen invasions (Loreau, 2000) as is the case in this study. Gut microbiota of PL at day 1 as well as of SD7 and CD7 was dominated by Gammaproteobacteria (SD7, 99.77%; CD7, 99.89%; Table 7), especially by opportunistic pathogen Acinetobacter (SD7, 98.41%; CD7, 98.72%) (Saejung et al, 2014) at the genus level ( Supplementary Table S5); we, thus, have reasons to believe that they were not in a healthy/stable state, further affirming the negative effects of salinity reduction on PL shrimp (and too, the black tiger shrimp PL, Rungrassamee et al, 2013).…”

In vitro evaluation of six chemical agents on smooth Brucella melitensis strain

“…Then, 0.5 mL MIC bacterial suspensions were sub-cultured in 4.5 mL liquid media without chemicals at 37°C with 5% CO 2 to determine bacterial survival. After 72 h, 100 μL of the mixed culture were spread over a TSA plate, and the MBCs of the tested disinfectants were determined [ 13 ]. Testing was performed in triplicate.…”