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Euan Smith - One of the best experts on this subject based on the ideXlab platform.

  • Detection of antibacterial-like activity on a silica surface: fluoroquinolones and their environmental metabolites
    Environmental Science and Pollution Research, 2012
    Co-Authors: Gareth Lewis, Albert Juhasz, Euan Smith
    Abstract:

    Background, scope, and aims Antibacterial fluoroquinolones (FQs) are third-generation antibiotics that are commonly used as therapeutic treatments of respiratory and urinary tract infections. They are used far less in intensively farmed animal production systems, though their use may be permitted in the veterinary treatments of flocks or in Medicated Feeds. When used, only a fraction of ingested parent FQ actually reaches the in vivo target site of infection, while the remainder is excreted as the parent FQ and its metabolized products. In many species’ metabolism, enrofloxacin (EF) is converted into ciprofloxacin (CF) while both FQs are classified as parent FQs in human treatments. It is therefore likely that both FQs and their metabolic products will contribute to a common pool of metabolites in biological wastes. Wastes from intensive farming practices are either directly applied to agricultural land without treatment or may be temporarily stored prior to disposal. However, human waste is treated in sewage treatment plants (STPs) where it is converted into biosolids. In the storage or treatment process of STPs, FQs and their in vivo metabolites are further converted into other environmental metabolites (FQEMs) by ex vivo physicochemical processes that act and interact to produce complex mixtures of FQEMs, some of which have antibacterial-like activities. Biosolids are then often applied to agricultural land as a fertilizer amendment where FQs and FQEMs can be further converted into additional FQEMs by soil processes. It is therefore likely that FQ-contaminated biowaste-treated soils will contain complex mixtures of FQEMs, some of which may have antibacterial-like activities that may be expressed on bacteria endemic to the receiving agricultural soil environment. Concern has arisen in the scientific and in the general community that repeated use of FQ-contaminated biowaste as fertilizer amendments of nutrient-impoverished agricultural land may create a selective environment in which FQ-resistant bacteria might grow. The likelihood of this happening will depend, to some extent, on whether bioactive FQEMs are first synthesized from the parent FQs by the action and interaction of in vivo and ex vivo processes producing bioactive FQEMs in biowastes and biosolids. The postulated creation of a selective environment will also depend, in part, on whether such bioactive FQEMs are biologically available to bacteria, which may, in turn, be influenced by soil type, amendment regime, and the persistence of the bioactive FQEMs. Additionally, soil bacteria and soil processes may be affected in different ways or extents by bioactive FQEMs that could possibly act additively or synergistically at ecological targets in these non-target bacteria. This is an important consideration, since, while parent FQs have well-defined ecological targets (DNA gyrase and topoisomerase IV) and modes of bactericidal action, the FQEMs and their possible modes of action on the many different species of soil bacteria is less well studied. It is therefore understandable that there is a lack of conclusive evidence directly attributing biosolid usage to any increase in FQ-resistant bacteria detected in biowaste-amended agricultural soil. However, a lack of evidence may simply imply that a causal relationship between biosolid usage programs and any detection of low levels of FQ-resistant bacteria in soils has yet to be established, rather than an assumption of no relationship whatsoever. Based on results presented in this paper, the precautionary principle should be applied in the usage of FQ-contaminated biosolids as fertilizer amendments of agricultural land. The aim of this research was to test whether any bioactive FQEMs of EF could be synthesized by aerobic fermentation processes using Mycobacterium gilvum (American Tissue Culture Collection) and a mixed culture of microorganisms derived from an agricultural soil. High-performance thin-layer chromatography (HPTLC) and bioautography were tested as screening techniques in the detection and analysis of bioactive FQEMs. Materials and methods FQEMs derived from M. gilvum and mixed (soil) culture aerobic ferments were fractionated using preparative HPTLC. A standard strain of Escherichia coli was then used as the reporter organism in a bioautography assay in the detection of bioactive-FQEMs on a mid-section of the HPTLC plate. Plate sections were reassembled, and a photograph was taken under low-intensity ultraviolet (UV) light to reveal regions that contained analytes that had UV chromophores and antibacterial-like activities. Results and discussion Many fractionated FQEMs displayed antibacterial-like activity while bound to silica gel HPTLC plates. These results also provide evidence that sufficient quantities of biologically active FQEMs were biologically available from a silica gel surface to prevent the adherent growth of E. coli . Six to seven FQEMs derived from EF using aerobic fermentation processes had antibacterial-like activities, while two FQEMs were also detectable using UV light. Furthermore, similar banding patterns of antibacterial-like activity were observed in both the monoculture ( M. gilvum ) and mixed culture bioautography assays, indicating that similar processes operated in both aerobic fermentations, either producing similar biologically active FQEMs or biologically active FQEMs that had similar physicochemical properties in both ferments. The simplest explanation for these findings is that the tested agricultural soil also contained mycobacteria that metabolized EF in a similar way to the purchased standard monoculture M. gilvum . Additionally, the marked contrast between the bioautography results and the UV results indicated that the presence of UV chromophores is not a prerequisite for the detection of antibacterial-like activity. Conclusions A reliance on spectrophotometric techniques in the detection of bioactive FQEMs in the environment may underestimate component antibacterial-like activity and, possibly, total antibacterial-like activity expressed by EF and its FQEMs. The described bioautography method provides a screening technique with which antibacterial-like activities derived from EF and possibly other FQs can be detected directly on silica gel HPTLC plates. Recommendations It is recommended that both bioassay and instrumental analytical techniques be used in any measurement of hazard and risk relating to antibacterial-like activities in the environment that are derived from fluoroquinolone antibiotics and their environmental metabolites.

  • Detection of antibacterial-like activity on a silica surface: fluoroquinolones and their environmental metabolites
    Environmental Science and Pollution Research, 2012
    Co-Authors: Gareth Lewis, Albert L. Juhasz, Euan Smith
    Abstract:

    Background, scope, and aims Antibacterial fluoroquinolones (FQs) are third-generation antibiotics that are commonly used as therapeutic treatments of respiratory and urinary tract infections. They are used far less in intensively farmed animal production systems, though their use may be permitted in the veterinary treatments of flocks or in Medicated Feeds. When used, only a fraction of ingested parent FQ actually reaches the in vivo target site of infection, while the remainder is excreted as the parent FQ and its metabolized products. In many species’ metabolism, enrofloxacin (EF) is converted into ciprofloxacin (CF) while both FQs are classified as parent FQs in human treatments. It is therefore likely that both FQs and their metabolic products will contribute to a common pool of metabolites in biological wastes. Wastes from intensive farming practices are either directly applied to agricultural land without treatment or may be temporarily stored prior to disposal. However, human waste is treated in sewage treatment plants (STPs) where it is converted into biosolids. In the storage or treatment process of STPs, FQs and their in vivo metabolites are further converted into other environmental metabolites (FQEMs) by ex vivo physicochemical processes that act and interact to produce complex mixtures of FQEMs, some of which have antibacterial-like activities. Biosolids are then often applied to agricultural land as a fertilizer amendment where FQs and FQEMs can be further converted into additional FQEMs by soil processes. It is therefore likely that FQ-contaminated biowaste-treated soils will contain complex mixtures of FQEMs, some of which may have antibacterial-like activities that may be expressed on bacteria endemic to the receiving agricultural soil environment. Concern has arisen in the scientific and in the general community that repeated use of FQ-contaminated biowaste as fertilizer amendments of nutrient-impoverished agricultural land may create a selective environment in which FQ-resistant bacteria might grow. The likelihood of this happening will depend, to some extent, on whether bioactive FQEMs are first synthesized from the parent FQs by the action and interaction of in vivo and ex vivo processes producing bioactive FQEMs in biowastes and biosolids. The postulated creation of a selective environment will also depend, in part, on whether such bioactive FQEMs are biologically available to bacteria, which may, in turn, be influenced by soil type, amendment regime, and the persistence of the bioactive FQEMs. Additionally, soil bacteria and soil processes may be affected in different ways or extents by bioactive FQEMs that could possibly act additively or synergistically at ecological targets in these non-target bacteria. This is an important consideration, since, while parent FQs have well-defined ecological targets (DNA gyrase and topoisomerase IV) and modes of bactericidal action, the FQEMs and their possible modes of action on the many different species of soil bacteria is less well studied. It is therefore understandable that there is a lack of conclusive evidence directly attributing biosolid usage to any increase in FQ-resistant bacteria detected in biowaste-amended agricultural soil. However, a lack of evidence may simply imply that a causal relationship between biosolid usage programs and any detection of low levels of FQ-resistant bacteria in soils has yet to be established, rather than an assumption of no relationship whatsoever. Based on results presented in this paper, the precautionary principle should be applied in the usage of FQ-contaminated biosolids as fertilizer amendments of agricultural land. The aim of this research was to test whether any bioactive FQEMs of EF could be synthesized by aerobic fermentation processes using Mycobacterium gilvum (American Tissue Culture Collection) and a mixed culture of microorganisms derived from an agricultural soil. High-performance thin-layer chromatography (HPTLC) and bioautography were tested as screening techniques in the detection and analysis of bioactive FQEMs.

David C Love - One of the best experts on this subject based on the ideXlab platform.

  • veterinary drug use in united states net pen salmon aquaculture implications for drug use policy
    Aquaculture, 2020
    Co-Authors: David C Love, Jillian P Fry, Felipe C Cabello, Christopher Good, Bjorn Tore Lunestad
    Abstract:

    Abstract Aquaculture now produces nearly half of the seafood consumed globally. Atlantic salmon (Salmo salar) is one of the top aquaculture products and the most valuable farmed marine finfish species in the United States (U.S.). The aim of this study is to better understand veterinary drug use in U.S. net pen Atlantic salmon aquaculture and compare these findings to other salmon producing countries and U.S. livestock. We collected and analyzed records on Atlantic salmon production and veterinary drug use in Maine (2003 to 2017) and Washington (2012 to 2017). Antimicrobial Medicated Feeds were used in 8% and 93% of production cycles in Maine and Washington, respectively. Oxytetratcycline was the primary drug used in both states. Maine used no antimicrobials in eight of the past 15 yrs., including none in 2017. Emamectin benzoate, an antiparasitic Medicated feed, was used in 28% production cycles in Maine (2014 to 2017; avg. 1.1 kg/yr) and no emamectin benzoate was administered in Washington over the time period studied. From 2014 to 2016, the U.S. farmed salmon industry contributed 0.8% ± 0.1% to annual global farmed salmon production and administered 1.2% ± 0.6% of antimicrobials used in global salmon farming. Over the same time period, Norway and Chile accounted for 53% ± 3% and 35% ± 3% of annual global production, and administered 0.06% ± 0.02% and 96% ± 0.09% of antimicrobials used in global salmon farming. Compared to U.S. terrestrial agriculture in 2016, the U.S. Atlantic salmon industry contributed 0.031% to U.S. food animal production and administered 0.057% of antimicrobials available to U.S. food animals. Based on the data we collected, the U.S. Atlantic salmon aquaculture industry is a relatively small user of antimicrobials compared to U.S. beef, pigs, poultry, and Chilean salmon industries. There are relatively few approved drugs in the U.S. to treat aquaculture diseases and more options are needed as well as continued work on vaccines. Antimicrobial resistance is a worldwide public health concern; the overuse or misuse of antimicrobials in any setting can compromise the treatment of bacterial infections. The U.S. net pen Atlantic salmon aquaculture industry appears to be the first U.S. food animal industry to report monthly antimicrobial use at the farm-level to the government. These data are critical to assess public health risks associated with antimicrobial use and resistance, and therefore, are needed from all U.S. food animal industries.

  • dose imprecision and resistance free choice Medicated Feeds in industrial food animal production in the united states
    Environmental Health Perspectives, 2011
    Co-Authors: David C Love, Meghan F Davis, Anna Bassett, Andrew Gunther, Keeve E Nachman
    Abstract:

    BACKGROUND: Industrial food animal production employs many of the same antibiotics or classes of antibiotics that are used in human medicine. These drugs can be administered to food animals in the form of free-choice Medicated Feeds (FCMF), where animals choose how much feed to consume. Routine administration of these drugs to livestock selects for microorganisms that are resistant to medications critical to the treatment of clinical infections in humans. OBJECTIVES: In this commentary, we discuss the history of Medicated Feeds, the nature of FCMF use with regard to dose delivery, and U.S. policies that address antimicrobial drug use in food animals. DISCUSSION: FCMF makes delivering a predictable, accurate, and intended dose difficult. Overdosing can lead to animal toxicity; underdosing or inconsistent dosing can result in a failure to resolve animal diseases and in the development of antimicrobial-resistant microorganisms. CONCLUSIONS: The delivery of antibiotics to food animals for reasons other than the treatment of clinically diagnosed disease, especially via free-choice feeding methods, should be reconsidered.

  • dose imprecision and resistance free choice Medicated Feeds in industrial food animal production in the united states
    Environmental Health Perspectives, 2011
    Co-Authors: David C Love, Meghan F Davis, Anna Bassett, Andrew Gunther, Keeve E Nachman
    Abstract:

    BackgroundIndustrial food animal production employs many of the same antibiotics or classes of antibiotics that are used in human medicine. These drugs can be administered to food animals in the fo...

  • Commentary Dose Imprecision and Resistance: Free-Choice Medicated Feeds in Industrial Food Animal Production in the United States
    2011
    Co-Authors: David C Love, Meghan F Davis, Anna Bassett, Andrew Gunther, Keeve E Nachman
    Abstract:

    Ba c k g r o u n d: Industrial food animal production employs many of the same antibiotics or classes of antibiotics that are used in human medicine. These drugs can be administered to food animals in the form of free-choice Medicated Feeds (FCMF), where animals choose how much feed to consume. Routine administration of these drugs to livestock selects for microorganisms that are resistant to medications critical to the treatment of clinical infections in humans. Objectives: In this commentary, we discuss the history of Medicated Feeds, the nature of FCMF use with regard to dose delivery, and U.S. policies that address antimicrobial drug use in food animals. Discussion: FCMF makes delivering a predictable, accurate, and intended dose difficult. Overdosing can lead to animal toxicity; underdosing or inconsistent dosing can result in a failure to resolve animal diseases and in the development of antimicrobial-resistant microorganisms. Co n c l u s i o n s: The delivery of antibiotics to food animals for reasons other than the treatment of clinically diagnosed disease, especially via free-choice feeding methods, should be reconsidered. Key w o r d s: antibiotic resistance, antibiotics, antimicrobials, cow, feed blocks, industrial food animal production, livestock, Medicated feed supplements, poultry, swine. Environ Health Perspec

Keeve E Nachman - One of the best experts on this subject based on the ideXlab platform.

  • dose imprecision and resistance free choice Medicated Feeds in industrial food animal production in the united states
    Environmental Health Perspectives, 2011
    Co-Authors: David C Love, Meghan F Davis, Anna Bassett, Andrew Gunther, Keeve E Nachman
    Abstract:

    BACKGROUND: Industrial food animal production employs many of the same antibiotics or classes of antibiotics that are used in human medicine. These drugs can be administered to food animals in the form of free-choice Medicated Feeds (FCMF), where animals choose how much feed to consume. Routine administration of these drugs to livestock selects for microorganisms that are resistant to medications critical to the treatment of clinical infections in humans. OBJECTIVES: In this commentary, we discuss the history of Medicated Feeds, the nature of FCMF use with regard to dose delivery, and U.S. policies that address antimicrobial drug use in food animals. DISCUSSION: FCMF makes delivering a predictable, accurate, and intended dose difficult. Overdosing can lead to animal toxicity; underdosing or inconsistent dosing can result in a failure to resolve animal diseases and in the development of antimicrobial-resistant microorganisms. CONCLUSIONS: The delivery of antibiotics to food animals for reasons other than the treatment of clinically diagnosed disease, especially via free-choice feeding methods, should be reconsidered.

  • dose imprecision and resistance free choice Medicated Feeds in industrial food animal production in the united states
    Environmental Health Perspectives, 2011
    Co-Authors: David C Love, Meghan F Davis, Anna Bassett, Andrew Gunther, Keeve E Nachman
    Abstract:

    BackgroundIndustrial food animal production employs many of the same antibiotics or classes of antibiotics that are used in human medicine. These drugs can be administered to food animals in the fo...

  • Commentary Dose Imprecision and Resistance: Free-Choice Medicated Feeds in Industrial Food Animal Production in the United States
    2011
    Co-Authors: David C Love, Meghan F Davis, Anna Bassett, Andrew Gunther, Keeve E Nachman
    Abstract:

    Ba c k g r o u n d: Industrial food animal production employs many of the same antibiotics or classes of antibiotics that are used in human medicine. These drugs can be administered to food animals in the form of free-choice Medicated Feeds (FCMF), where animals choose how much feed to consume. Routine administration of these drugs to livestock selects for microorganisms that are resistant to medications critical to the treatment of clinical infections in humans. Objectives: In this commentary, we discuss the history of Medicated Feeds, the nature of FCMF use with regard to dose delivery, and U.S. policies that address antimicrobial drug use in food animals. Discussion: FCMF makes delivering a predictable, accurate, and intended dose difficult. Overdosing can lead to animal toxicity; underdosing or inconsistent dosing can result in a failure to resolve animal diseases and in the development of antimicrobial-resistant microorganisms. Co n c l u s i o n s: The delivery of antibiotics to food animals for reasons other than the treatment of clinically diagnosed disease, especially via free-choice feeding methods, should be reconsidered. Key w o r d s: antibiotic resistance, antibiotics, antimicrobials, cow, feed blocks, industrial food animal production, livestock, Medicated feed supplements, poultry, swine. Environ Health Perspec

Gareth Lewis - One of the best experts on this subject based on the ideXlab platform.

  • Detection of antibacterial-like activity on a silica surface: fluoroquinolones and their environmental metabolites
    Environmental Science and Pollution Research, 2012
    Co-Authors: Gareth Lewis, Albert Juhasz, Euan Smith
    Abstract:

    Background, scope, and aims Antibacterial fluoroquinolones (FQs) are third-generation antibiotics that are commonly used as therapeutic treatments of respiratory and urinary tract infections. They are used far less in intensively farmed animal production systems, though their use may be permitted in the veterinary treatments of flocks or in Medicated Feeds. When used, only a fraction of ingested parent FQ actually reaches the in vivo target site of infection, while the remainder is excreted as the parent FQ and its metabolized products. In many species’ metabolism, enrofloxacin (EF) is converted into ciprofloxacin (CF) while both FQs are classified as parent FQs in human treatments. It is therefore likely that both FQs and their metabolic products will contribute to a common pool of metabolites in biological wastes. Wastes from intensive farming practices are either directly applied to agricultural land without treatment or may be temporarily stored prior to disposal. However, human waste is treated in sewage treatment plants (STPs) where it is converted into biosolids. In the storage or treatment process of STPs, FQs and their in vivo metabolites are further converted into other environmental metabolites (FQEMs) by ex vivo physicochemical processes that act and interact to produce complex mixtures of FQEMs, some of which have antibacterial-like activities. Biosolids are then often applied to agricultural land as a fertilizer amendment where FQs and FQEMs can be further converted into additional FQEMs by soil processes. It is therefore likely that FQ-contaminated biowaste-treated soils will contain complex mixtures of FQEMs, some of which may have antibacterial-like activities that may be expressed on bacteria endemic to the receiving agricultural soil environment. Concern has arisen in the scientific and in the general community that repeated use of FQ-contaminated biowaste as fertilizer amendments of nutrient-impoverished agricultural land may create a selective environment in which FQ-resistant bacteria might grow. The likelihood of this happening will depend, to some extent, on whether bioactive FQEMs are first synthesized from the parent FQs by the action and interaction of in vivo and ex vivo processes producing bioactive FQEMs in biowastes and biosolids. The postulated creation of a selective environment will also depend, in part, on whether such bioactive FQEMs are biologically available to bacteria, which may, in turn, be influenced by soil type, amendment regime, and the persistence of the bioactive FQEMs. Additionally, soil bacteria and soil processes may be affected in different ways or extents by bioactive FQEMs that could possibly act additively or synergistically at ecological targets in these non-target bacteria. This is an important consideration, since, while parent FQs have well-defined ecological targets (DNA gyrase and topoisomerase IV) and modes of bactericidal action, the FQEMs and their possible modes of action on the many different species of soil bacteria is less well studied. It is therefore understandable that there is a lack of conclusive evidence directly attributing biosolid usage to any increase in FQ-resistant bacteria detected in biowaste-amended agricultural soil. However, a lack of evidence may simply imply that a causal relationship between biosolid usage programs and any detection of low levels of FQ-resistant bacteria in soils has yet to be established, rather than an assumption of no relationship whatsoever. Based on results presented in this paper, the precautionary principle should be applied in the usage of FQ-contaminated biosolids as fertilizer amendments of agricultural land. The aim of this research was to test whether any bioactive FQEMs of EF could be synthesized by aerobic fermentation processes using Mycobacterium gilvum (American Tissue Culture Collection) and a mixed culture of microorganisms derived from an agricultural soil. High-performance thin-layer chromatography (HPTLC) and bioautography were tested as screening techniques in the detection and analysis of bioactive FQEMs. Materials and methods FQEMs derived from M. gilvum and mixed (soil) culture aerobic ferments were fractionated using preparative HPTLC. A standard strain of Escherichia coli was then used as the reporter organism in a bioautography assay in the detection of bioactive-FQEMs on a mid-section of the HPTLC plate. Plate sections were reassembled, and a photograph was taken under low-intensity ultraviolet (UV) light to reveal regions that contained analytes that had UV chromophores and antibacterial-like activities. Results and discussion Many fractionated FQEMs displayed antibacterial-like activity while bound to silica gel HPTLC plates. These results also provide evidence that sufficient quantities of biologically active FQEMs were biologically available from a silica gel surface to prevent the adherent growth of E. coli . Six to seven FQEMs derived from EF using aerobic fermentation processes had antibacterial-like activities, while two FQEMs were also detectable using UV light. Furthermore, similar banding patterns of antibacterial-like activity were observed in both the monoculture ( M. gilvum ) and mixed culture bioautography assays, indicating that similar processes operated in both aerobic fermentations, either producing similar biologically active FQEMs or biologically active FQEMs that had similar physicochemical properties in both ferments. The simplest explanation for these findings is that the tested agricultural soil also contained mycobacteria that metabolized EF in a similar way to the purchased standard monoculture M. gilvum . Additionally, the marked contrast between the bioautography results and the UV results indicated that the presence of UV chromophores is not a prerequisite for the detection of antibacterial-like activity. Conclusions A reliance on spectrophotometric techniques in the detection of bioactive FQEMs in the environment may underestimate component antibacterial-like activity and, possibly, total antibacterial-like activity expressed by EF and its FQEMs. The described bioautography method provides a screening technique with which antibacterial-like activities derived from EF and possibly other FQs can be detected directly on silica gel HPTLC plates. Recommendations It is recommended that both bioassay and instrumental analytical techniques be used in any measurement of hazard and risk relating to antibacterial-like activities in the environment that are derived from fluoroquinolone antibiotics and their environmental metabolites.

  • Detection of antibacterial-like activity on a silica surface: fluoroquinolones and their environmental metabolites
    Environmental Science and Pollution Research, 2012
    Co-Authors: Gareth Lewis, Albert L. Juhasz, Euan Smith
    Abstract:

    Background, scope, and aims Antibacterial fluoroquinolones (FQs) are third-generation antibiotics that are commonly used as therapeutic treatments of respiratory and urinary tract infections. They are used far less in intensively farmed animal production systems, though their use may be permitted in the veterinary treatments of flocks or in Medicated Feeds. When used, only a fraction of ingested parent FQ actually reaches the in vivo target site of infection, while the remainder is excreted as the parent FQ and its metabolized products. In many species’ metabolism, enrofloxacin (EF) is converted into ciprofloxacin (CF) while both FQs are classified as parent FQs in human treatments. It is therefore likely that both FQs and their metabolic products will contribute to a common pool of metabolites in biological wastes. Wastes from intensive farming practices are either directly applied to agricultural land without treatment or may be temporarily stored prior to disposal. However, human waste is treated in sewage treatment plants (STPs) where it is converted into biosolids. In the storage or treatment process of STPs, FQs and their in vivo metabolites are further converted into other environmental metabolites (FQEMs) by ex vivo physicochemical processes that act and interact to produce complex mixtures of FQEMs, some of which have antibacterial-like activities. Biosolids are then often applied to agricultural land as a fertilizer amendment where FQs and FQEMs can be further converted into additional FQEMs by soil processes. It is therefore likely that FQ-contaminated biowaste-treated soils will contain complex mixtures of FQEMs, some of which may have antibacterial-like activities that may be expressed on bacteria endemic to the receiving agricultural soil environment. Concern has arisen in the scientific and in the general community that repeated use of FQ-contaminated biowaste as fertilizer amendments of nutrient-impoverished agricultural land may create a selective environment in which FQ-resistant bacteria might grow. The likelihood of this happening will depend, to some extent, on whether bioactive FQEMs are first synthesized from the parent FQs by the action and interaction of in vivo and ex vivo processes producing bioactive FQEMs in biowastes and biosolids. The postulated creation of a selective environment will also depend, in part, on whether such bioactive FQEMs are biologically available to bacteria, which may, in turn, be influenced by soil type, amendment regime, and the persistence of the bioactive FQEMs. Additionally, soil bacteria and soil processes may be affected in different ways or extents by bioactive FQEMs that could possibly act additively or synergistically at ecological targets in these non-target bacteria. This is an important consideration, since, while parent FQs have well-defined ecological targets (DNA gyrase and topoisomerase IV) and modes of bactericidal action, the FQEMs and their possible modes of action on the many different species of soil bacteria is less well studied. It is therefore understandable that there is a lack of conclusive evidence directly attributing biosolid usage to any increase in FQ-resistant bacteria detected in biowaste-amended agricultural soil. However, a lack of evidence may simply imply that a causal relationship between biosolid usage programs and any detection of low levels of FQ-resistant bacteria in soils has yet to be established, rather than an assumption of no relationship whatsoever. Based on results presented in this paper, the precautionary principle should be applied in the usage of FQ-contaminated biosolids as fertilizer amendments of agricultural land. The aim of this research was to test whether any bioactive FQEMs of EF could be synthesized by aerobic fermentation processes using Mycobacterium gilvum (American Tissue Culture Collection) and a mixed culture of microorganisms derived from an agricultural soil. High-performance thin-layer chromatography (HPTLC) and bioautography were tested as screening techniques in the detection and analysis of bioactive FQEMs.

Holth Riseth - One of the best experts on this subject based on the ideXlab platform.

  • evaluation of florfenicol in atlantic salmon salmo salar l efficacy against furunculosis due to aeromonas salmonicida and cold water vibriosis due to vibrio salmonicida
    Journal of Fish Diseases, 1998
    Co-Authors: Holth Riseth
    Abstract:

    Two replicated controlled trials were conducted to determine the efficacy of florfenicol against Aeromonas salmonicida and Vibrio salmonicida infections in Atlantic salmon, Salmo salar L., smolts kept in 25‰ salt water. Infection with A. salmonicida was treated with florfenicol, oxolinic acid, oxytetracycline, trimethoprim/sulphadiazine or flumequine, whereas the V. salmonicida infection was treated with florfenicol or oxolinic acid only. A. salmonicida infection was induced by the introduction of cohabitant fish previously inoculated intraperitoneally. Medication started simultaneously in all test tanks on the first day of specific mortality among test fish. V. salmonicida infection was induced by intraperitoneal inoculation of all test fish. Medication started 1 day after infection. Medicated Feeds were produced by coating the antibacterials on standard feed pellets, and administered twice daily for 10 consecutive days. With the dose used in the present trials, florfenicol was highly effective in reducing specific mortalities due to both infections. It was slightly more effective than oxolinic acid and trimethoprim/sulphadiazine against A. salmonicida infection. There was no significant difference between florfenicol and oxolinic acid in reducing specific mortalities due to V. salmonicida.