Control of ExternalAeromonas salmonicida: Topical Disinfection of Salmonids with Chloramine-T

Abstract

Brook trout Salvelimts fontinalis were treated with single 60-min static baths of 250 mg formalin/L. 3 r # NaCL and 15 mg Chloramine-T/L to evaluate the efficacy of these compounds against external infections of Aeromonas salmonicida. Prevalence of A. salmonicida was significantly lower in brook trout treated with Chloramine-T than among those treated with formalin or salt. Further laboratory tests substantiated the therapeutic value of a single treatment of Chloramine-"I' (15 mg/L) against A. salmonicida. In two experiments, viable counts of A. salmonicida in mucus did not vary among replicate groups of treated brook trout, but the counts for treated fish were significantly (P < 0.05) lower than those for untreated controls. In vitro tube dilution assays indicated that mean minimum inhibitory concentrations of Chloramine-T for 10 isolates of A. salmonicida were 9.0 mg/L for I h and 2.25 mg/L for 24 h. In field trials at the White River National Fish Hatchery (Bethel, Vermont), the pathogen was detected principally as an external infection of juvenile Atlantic salmon Salmo salar maintained in two culture ponds. In one pond, the bacterium accounted for 100% of the total distribution of microflora isolated from mucus. Seven days after treatment with Chloramine-T. A. salmonicida accounted for 11% of the total bacterial counts identified from these fish. In the second pond. A. salmonicida composed 3% of the counts of bacteria isolated from the mucus of fish before treatment but was not isolated after treatment.

The Effect of Disinfection Strategies on Transmission of Aeromonas salmonicida and Yersinia ruckeri in a Recirculating Aquaculture System

“…Furunculosis occurred in both tests of trial one and ERM occurred in one of two tests in trial one. Cipriano et al (1996b) reported that 9.0 ppm Chloramine-T inhibited A. salmonicida, but in this study the efficacy of Chloramine-T disinfection for either pathogen was not consistent. Although ERM did not occur following Chloramine-T disinfection, the pathogen was isolated from one biofilter after disinfection.…”

“…If disease occurred when the system was restocked, fish were removed and a I-hour 10-ppm Chloramine-T (N-chloro-p-toluene sulfonamide sodium salt, Sigma Chemical Co., St. Louis, MO, USA) treatment of the entire recirculating system was carried out and the system restocked with char or rainbow trout. A concentration of 8.5 ppm Chloramine-T has been shown to be effective in controlling BGD (From 1980) and isolates of A. salmonicida were found to be inhibited by 9.0 ppm Chloramine-T (Cipriano et al 1996b). However, efficacy of Chloramine-T for disinfection of Yersinia ruckeri has not been reported.…”

Drugs in salmonid aquaculture – A review

“…This is particularly the case for endemic infectious diseases of mucosal surfaces of terrestrial livestock (Meek et al, 1986;Van Donkersgoed, 1992;Gallo & Berg, 1995). Reflecting a similar paradigm, the use of prophylactic chemical bath treatments is an emerging routine practice in the high intensity farming of catfish (Bodensteiner et al, 1993) and various salmonid species Thorburn & Moccia, 1993;Cipriano et al, 1996). This emerging use pattern reflects:…”

Disinfection of Water Used for Human and Animal Consumption

“…The use of chloramine-T solutions for disinfection of water includes its use in aquaculture. Tests performed on brook trout by Cipriano et al [24] substantiated the therapeutic value of single treatment with chloramine-T (15 mg/L) against Aeromonas salmonicida, which was more successful than that treatment with formalin or salt.…”