Carrier state induced by oxytetracycline therapy against streptococcosis in Nile tilapia, Oreochromis niloticus (L.)

Effects of a dietary organic acids blend and oxytetracycline on the growth, nutrient utilization and total cultivable gut microbiota of the red hybrid tilapia,Oreochromissp., and resistance toStreptococcus agalactiae

“…A significant limiting factor to aquaculture expansion and productivity is disease and in response, there is a great reliance on antibiotics either to treat disease or at lower doses as a prophylactic and growth promoter, especially in Asia (Hernández‐Serrano ). Of particular concern to tilapia aquaculture are bacterial diseases caused by the Streptococcal groups, such as Streptococcus agalactiae which can cause widespread mortalities, particularly in warm water and high intensive culture systems in various countries (Suanyuk, Kong, Ko, Gilbert & Supamattaya ; Musa, Wei, Musa, Hamdan, Leon, Wee, Amal, Kutty & Abdullah ; Faria, Leal, Carvalho‐Castro, Leite & Figueiredo ). However, research is increasingly showing that the overuse of antibiotics can lead to adverse consequences such as the development of antibiotic resistant bacteria that may be harmful to the host animal, environment and potentially to human consumers (reviewed by Kümmerer ; Marshall & Levy ).…”

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“…Oxytetracycline is the main antibiotic for the treatment of clinical infections by experimental studies with clinical bacterial strains demonstrating changes in its efficacy. 3 In addition; the present study demonstrates how small increases in MIC could have a high impact on therapeutic efficacy. This study demonstrates, probabilistically, that cure would be found in 80% of the animals, mortality in 2.5% and presence of carriers in 16% of the animals would be found by infection with Streptococcus agalactiae with MIC of 0.125μg/ml.…”

“…Oxytetracycline, a tetracycline antibiotic with a broad spectrum of action, is the preferred antibiotic for the treatment of bacterial diseases in aquaculture, due to its relative efficacy, low cost 2 and because it has the diffusion capacity in body fluids and tissues. 3 The susceptibility to antibiotics obtained by the Minimum Inhibitory Concentration (MIC) of bacterial strains isolated from clinical cases can be used to classify isolates as wild-type and non-wild-type and to calculate provisional epidemiological cut-off values. 3,4 Studies of experimental infections carried out in Brazil with Streptococcus agalactiae with MIC of 0.24ug/ml treated with oral doses of 100mg/kg of oxytetracycline every 12hours showed 20% of mortality rates and 60 % of persistence of infected animals.…”

“…3 The susceptibility to antibiotics obtained by the Minimum Inhibitory Concentration (MIC) of bacterial strains isolated from clinical cases can be used to classify isolates as wild-type and non-wild-type and to calculate provisional epidemiological cut-off values. 3,4 Studies of experimental infections carried out in Brazil with Streptococcus agalactiae with MIC of 0.24ug/ml treated with oral doses of 100mg/kg of oxytetracycline every 12hours showed 20% of mortality rates and 60 % of persistence of infected animals. 3 The PK/PD models relate pharmacokinetic (PK) parameters with pharmacodynamic parameters (PD) and are widely used as indicators of the efficacy of antibiotic treatments in humans and animals.…”

“…3,4 Studies of experimental infections carried out in Brazil with Streptococcus agalactiae with MIC of 0.24ug/ml treated with oral doses of 100mg/kg of oxytetracycline every 12hours showed 20% of mortality rates and 60 % of persistence of infected animals. 3 The PK/PD models relate pharmacokinetic (PK) parameters with pharmacodynamic parameters (PD) and are widely used as indicators of the efficacy of antibiotic treatments in humans and animals. These models optimize antimicrobial therapy and minimize resistance selection.…”