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Volume 124, Issues 1–2,
20 September 2007
, Pages 73-81
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The aim of this study was to compare the in vitro antimicrobial activity of the veterinary fluoroquinolones against a panel of recently isolated porcine and bovine bacterial pathogens. The study used enrofloxacin as a benchmark against which other agents were compared, being the most common fluoroquinolone used in treatment of bovine and porcine infections. The activity of ciprofloxacin was also assessed as it is the main metabolite of enrofloxacin in cattle. Enrofloxacin and ciprofloxacin generally showed higher antibacterial activity, in terms of MIC50 values, for most pathogen species when compared with marbofloxacin, difloxacin, danofloxacin and norfloxacin. Ciprofloxacin showed significantly greater in vitro antibacterial activity than enrofloxacin against M. haemolytica, P. multocida and E. coli, whereas enrofloxacin showed greater activity than ciprofloxacin against S. aureus. Marbofloxacin was significantly more active than enrofloxacin against M. haemolytica, E. coli and B. bronchiseptica but less active against P. multocida, S. aureus, coagulase negative Staphylococci, S. dysgalactiae, S. uberis, A. pleuropneumoniae and S. suis. Danofloxacin was significantly less active than enrofloxacin against P. multocida, E. coli, S. uberis, A. pleuropneumoniae and S. suis. Enrofloxacin and its metabolite ciprofloxacin showed the highest in vitro activities against most bovine pathogens tested and the porcine pathogens also showed a high degree of sensitivity to enrofloxacin. These data facilitate further pharmacokinetic/pharmacodynamic comparison of fluoroquinolones currently used in veterinary medicine.
The use of pharmacokinetic/pharmacodynamic (PK/PD) analyses is of increasing importance during the development of new antimicrobial agents, to optimise treatment strategies (McKellar et al., 2004) and reduce the development of antibiotic resistant bacterial strains (Lathers, 2002). PK characterisation involves defining parameters such as the area under the concentration time-curve (AUC) and the maximum plasma concentration (Cmax) (Coulet et al., 2002). The most commonly used PD parameter is minimum inhibitory concentration (MIC), which is key to the derivation of therapeutic AUC/MIC and Cmax/MIC ratios. PK and PD components can be combined experimentally either by integration or by modelling (Kietzmann et al., 2004, McKellar et al., 2004, Toutain and Lees, 2004).
Fluoroquinolones are important therapeutic agents in veterinary medicine, having a broad range of antimicrobial activity (Brown, 1996). They act by inhibiting the action of the topoisomerase gene products thereby disrupting DNA replication (Hawkey, 2003). Many studies assess the MICs of fluoroquinolones against veterinary pathogen collections, to compare the efficacy of the different agents. However, such studies have a number of limitations: (1) most do not consider the full panel of veterinary fluoroquinolones (Cruz et al., 1997, De Oliveira et al., 2000, Yoshimura et al., 2001, Yoshimura et al., 2002a, Yoshimura et al., 2002b, Zhao et al., 2005); (2) studies often use differing methodologies, introducing variability into the absolute MIC values attained (Gombert and Aulicino, 1985, Koeth et al., 2000, Wallmann et al., 2006) even when using procedures standardised according to the Clinical and Laboratory Standards Institute ([CLSI] NCCLS, 2002); (3) a number of fluoroquinolone resistance monitoring studies do not accurately determine true in vitro potencies, as antibiotic concentrations at the lower end of the sensitivity range were not used (Watts et al., 1997, Mevius and Hartman, 2000, Yoshimura et al., 2001); (4) MIC values should be determined for a large group of isolates for each type of organism, minimising the impact of any variation between isolates (Lees et al., 2004, Toutain and Lees, 2004). To overcome these limitations in the background data we assessed the in vitro antimicrobial activities of a range of fluoroquinolones relevant to veterinary practice, comprising enrofloxacin and the comparators ciprofloxacin, danofloxacin, difloxacin, marbofloxacin and norfloxacin. Though not licensed for use in veterinary medicine the inclusion of ciprofloxacin was considered important, as it is the main enrofloxacin metabolite in cattle.
Minimum inhibitory concentration testing
MIC values were determined using the microbroth dilution method in accordance with the CLSI guidelines (NCCLS, 2002). Sensititre microtitre plates (MCS Diagnostics, Swalmen, Netherlands) were coated with 11 or 12 two-fold dilutions of the fluoroquinolones: enrofloxacin (0.002–4μg/mL), ciprofloxacin (0.002–4μg/mL), danofloxacin (0.002–4μg/mL), difloxacin (0.002–4μg/mL), norfloxacin (0.004–4μg/mL) and marbofloxacin (0.002–4μg/mL).
Ten bovine and porcine pathogen species, comprising 422 isolates
The in vitro sensitivity of 422 bacterial isolates, covering important porcine and bovine pathogens, to six fluoroquinolones was determined. The MIC data from individual isolates were pooled, for each pathogen species, and used to determine their MIC50 values. It was considered appropriate to pool MIC data for porcine and bovine P. multocida isolates and mammary and intestinal E. coli isolates, as previous studies indicate that the intrinsic antibiotic susceptibility is comparable for all
This study assessed the in vitro activity of all currently relevant veterinary fluoroquinolones used to target a range of bovine and porcine pathogens. This study used enrofloxacin as a benchmark against which other agents were compared, as enrofloxacin represents the most common fluoroquinolone used in the treatment of bovine and porcine infections and is also currently used as the reference fluoroquinolone in commercially available veterinary antibiotic disc sensitivity assays. Comparison of
This is the first study to directly compare the in vitro sensitivities of a large panel of clinically relevant bovine and porcine pathogen isolates, against all veterinary fluoroquinolones and under identical laboratory conditions. The study overcomes the limitations associated with previous in vitro susceptibility studies by: (a) considering the entire spectrum of relevant fluoroquinolones, (b) using a consistent standardised methodology as recommended by the CLSI and (c) testing an
The authors would like to thank Dr. M. Vanrobaeys (Belgium) and Dr. R. Danguy (France) for their help in providing local pathogen isolates.
- M. Carbone et al.
Activity and postantibiotic effect of marbofloxacin, enrofloxacin, difloxacin and ciprofloxacin against feline Bordetella bronchiseptica isolates
- A.P. De Oliveira et al.
Antimicrobial susceptibility of Staphylococcus aureus isolated from bovine mastitis in Europe and the United States
J. Dairy Sci.
- R.N. Jones et al.
Multicenter in vitro evaluation of lomefloxacin (NY-198, SC-47111), including tests against nearly 7,000 bacterial isolates and preliminary recommendations for susceptibility testing
Diagn. Microbiol. Infect. Dis.
- R.N. Jones et al.
In vitro susceptibility testing and quality control parameters for sarafloxacin (A-56620): a fluoroquinolone used for treatment and control of colibacillosis in poultry
Diagn. Microbiol. Infect. Dis.
- D.A. Mosier
Vet. Clin. North Am. Food Anim. Pract.
- J. Wallmann et al.
Results of an interlaboratory test on antimicrobial susceptibility testing of bacteria from animals by broth microdilution
Int. J. Antimicrob. Agents
- S. Zhao et al.
Antimicrobial susceptibility and molecular characterization of avian pathogenic Escherichia coli isolates
- A.L. Barry et al.
Antibacterial activities of ciprofloxacin, norfloxacin, oxolinic acid, cinoxacin, and nalidixic acid
Antimicrob. Agents Chemother
- S.M. Bhavnani et al.
Pharmacodynamics in the evaluation of drug regimens
- S.A. Brown
Fluoroquinolones in animal health
J. Vet. Pharmacol. Ther.
In vitro and in vivo pharmacodynamic properties of the fluoroquinolone ibafloxacin
J. Vet. Pharmacol. Ther.
Comparative in vitro study on the susceptibility and emergence of mutants resistant to danofloxacin and ciprofloxacin among Staphylococcus aureus isolated from bovine mastitis
Revista de Microbiol.
Pharmacokinetic and pharmacodynamic comparison of Baytril 5% and 10% in cattle
Potency and postantibiotic effect of four fluoroquinolones against feline Pasteurella multocida isolates
Comparison of agar dilution, microtitre broth dilution and tube macrodilution susceptibility testing of ciprofloxacin against several pathogens at two different inocula
J. Antimicrob. Chemother
Mechanisms of quinolone action and microbial response
J. Antimicrob. Chemother
Antimicrobial susceptibility testing of bacteria isolated from animals: considerations concerning the determination of breakpoints-clinical pharmacological view
Berliner und Münchener Tierärztliche Wochenschrift
Cited by (46)
Clonal distribution and antimicrobial resistance of methicillin-susceptible and -resistant Staphylococcus aureus strains isolated from broiler farms, slaughterhouses, and retail chicken meat
2022, Poultry Science
Citation Excerpt :
Susceptibilities to linezolid (LZD), teicoplanin (TEC), vancomycin (VAN), and tigecycline (TGC) were determined using the standard E-test (Bio Mérieux, France) on Mueller–Hinton agar (Difco Laboratories) plates. For evaluation of fluoroquinolone resistance, minimum inhibitory concentrations (MICs) for CIP (ranging from 0.0625 to 256 μg/mL) and ENR (ranging from 0.5 to 64 μg/mL) were determined using the standard broth microdilution assay (Grobbel et al., 2007; CLSI, 2018). The resistance breakpoints for the antimicrobial agents were interpreted based on the CLSI documents of VET01S and M100 (CLSI, 2020; CLSI, 2022).
Colonization of food-producing animals by antimicrobial-resistant Staphylococcus aureus, especially methicillin-resistant S. aureus (MRSA), has become a serious public health problem worldwide. In the current study, clonal diversities of livestock-associated S. aureus isolates collected from broiler farms, slaughterhouses, and retail chicken meat were examined. Two-hundred S. aureus isolates (43 MRSA and 157 methicillin-susceptible S. aureus [MSSA] isolates) were analyzed to determine 1) the genotypes of the isolates (multilocus sequence, agr, and spa types), 2) the methicillin resistance phenotype and staphylococcal cassette chromosome mec (SCCmec) types, 3) the antimicrobial resistance profiles, and 4) the mutational changes in gyrA, gyrB, parC, and parE in fluoroquinolone-resistant isolates. Fifteen different sequence types (STs) of MSSA strains displaying a relatively high degree of genetic diversity were detected in broiler farms, slaughterhouses, and retail chicken meat. In contrast to MSSA, 2 dominant genetic lineages of MRSA (ST692-SCCmecV with t2249 spa type, and ST188-SCCmecIVa with spa type t189) were found in healthy broilers. The high prevalence of ST692 and ST188 in healthy broilers is associated with high levels of multiple antimicrobial-resistance phenotypes, particularly fluoroquinolone resistance. All fluoroquinolone-resistant isolates carried double point mutations in gyrA (S84L) and parC (S80F), regardless of STs or methicillin resistance. Notably, only the ST188 lineage carried an additional third mutation in gyrB (D494N), correlating with enhanced ciprofloxacin minimum inhibitory concentration values versus the strains with double mutations. These results provide important insights into the genetic diversity of antimicrobial-resistant S. aureus strains associated with the chicken meat production chain, including healthy broilers, in Korea.
Lanthanide-sensitized luminescence and chemiluminescence in the systems containing most often used medicines; a review
2020, Journal of Luminescence
Citation Excerpt :
They attack two enzymes of key importance for bacteria replication: DNA gyrase and topoisomerase IV . They are characterized by a wide range of activity  and are divided into a few generations of different structures so also different strength and range of bactericidal activity [55,56]. Chemical modifications of quinolone include mainly the substitution reactions at positions N-1, C-6 (addition of fluorine group), C-7 (addition of piperazinyl or piperazine derivative group) and at C-8  (Table 3).
The lanthanides ions with their well-defined energy levels make excellent objects for investigation of energy transfer processes involving a wide range of organic compounds in different chemical environments. This paper presents a review of literature on the lanthanide-sensitized luminescence and chemiluminescence in the systems containing medicines from the three most often used groups: tetracyclines, fluoroquinolones and nonsteroidal anti-inflammatory drugs. Enhanced emission of lanthanides(III) as a result of formation of stable complexes as a result of intra- and intermolecular energy transfer has been widely used for design of sensitive methods for determination of the above medicines and a number of other analytes. This review is concerned with the use of lanthanides as sensitizers in chemiluminescence systems, instead of classical organic dyes. The review of literature presented in this paper is focused on the correlation of the drug structure and the lanthanide ion (Ln(III)) used as a sensitizer. Also the advanced aspects of the lanthanide-sensitized luminescence related to the use of nanomaterials doped with lanthanide ions in biology and medicine and comments on predicted challenges and perspectives of analytical chemistry based on the methods involving the lanthanide-sensitized luminescence and chemiluminescence.
Occurrence of enrofloxacin in overflows from animal lot and residential sewage lagoons and a receiving-stream
Citation Excerpt :
Specifically, Baytril, the trade name for ENRO, was used to control cattle infections. The antibacterial is known as the most commonly used fluoroquinolone to treat bovine and porcine infections (Grobbel et al., 2007) such as colibacillosis, salmonellosis, mycoplasmosis and pasteurellosis (Bona et al., 2016). ENRO was purchased as a standard from Sigma-Aldrich (St. Louis, Missouri, USA).
Enrofloxacin (ENRO), a fluoroquinolone, was quantified in overflows from an animal lot and residential sewage lagoons and in a receiving-stream (Gans Creek). The concentrations of ENRO in samples was determined by high-performance liquid chromatography − tandem mass spectrometry. In total, ninety samples including duplicates were analyzed during several monthly sampling campaigns. The samples collected represented the residential sewage lagoon overflow (RLO), animal lot lagoon overflow (ALLO), the combined overflows (RLO and ALLO), and Gans Creek (upstream, midstream and downstream positions). The frequency of detection of ENRO was 90% for RLO and 100% for both ALLO and Gans Creek. The highest concentration of ENRO (0.44 μg/L) was found in ALLO sample collected during high precipitation. ENRO levels found in RLO samples ranged from < LOQ to 259 ng/L and the highest value observed also coincided with high flow. The levels of ENRO found in Gans Creek ranged from 17–216 ng/L. A preliminary ecotoxicological assessment was conducted through calculation of the risk quotients (RQs) for organisms based on the ratio of the measured environmental concentrations in this study to the predicted-no-effect-concentrations (acute and chronic effect) data. From the RQs, high risks were observed for Microcystis aeruginosa (cyanobacteria; RQ = 4.4); Anabaena flosaquae (cyanobacteria; RQ = 1.3); and Lemna minor (aquatic vascular plant; RQ = 2.0). The long-term effects of mixtures of PHCs on Gans Creek watershed are probable.
Effect of bovine ABCG2 Y581S polymorphism on concentrations in milk of enrofloxacin and its active metabolite ciprofloxacin
2016, Journal of Dairy Science
Citation Excerpt :
Thus, in the case of mastitis, CIPRO would be the key molecule acting against the infectious agent. Moreover, the Cmax values obtained for milk (Table 1, Figure 3) were higher than the in vitro MIC for isolates from mastitis (Grobbel et al., 2007; Thomas et al., 2015). Bearing in mind that the MIC values of ENRO and CIPRO for many pathogens have been reported to be <0.1 μg/mL (Prescott and Yielding, 1990), if this concentration (0.1 μg/mL) is taken as the MIC of these compounds, the therapeutic Cmax/MIC ratios can be estimated using the milk parameters for the active metabolite CIPRO (Table 1), which highlight an increase from 5.1 in Y/Y to 10.3 in Y/S animals, respectively.
The ATP-binding cassette transporter G2 (ABCG2) is involved in the secretion of several drugs into milk. The bovine Y581S ABCG2 polymorphism increases the secretion into milk of the fluoroquinolone danofloxacin in Holstein cows. Danofloxacin and enrofloxacin are the fluoroquinolones most widely used in veterinary medicine. Both enrofloxacin (ENRO) and its active metabolite ciprofloxacin (CIPRO) reach milk at relatively high concentrations. The aim of this work was to study the effect of the bovine Y581S ABCG2 polymorphism on in vitro transport as well as on concentrations in plasma and in milk of ENRO and CIPRO. Experiments using cells overexpressing bovine ABCG2 showed the effects of ABCG2 on the transport of CIPRO, demonstrating more efficient in vitro transport of this antimicrobial by the S581 variant as compared with the Y581 variant. Animal studies administering 2.5mg/kg of ENRO subcutaneously to Y/Y 581 and Y/S 581 cows revealed that concentrations in plasma of ENRO and CIPRO were significantly lower in Y/S animals. Regardless of the genotype, the antimicrobial profile in milk after the administration of ENRO was predominantly of CIPRO. With respect to the genotype effects on the amounts of drugs present in milk, AUC0–24 values were more than 1.2 times higher in Y/S cows for ENRO and 2.2 times for CIPRO, indicating a greater capacity of Y581S to transfer these drugs into milk. These results emphasize the clinical relevance of this polymorphism as a factor affecting the concentrations in plasma and in milk of drugs of importance in veterinary medicine.
Comparative activities of selected fluoroquinolones against dynamic populations of Actinobacillus pleuropneumoniae in an in vitro model of time-kill continuous culture experiment
2013, International Journal of Antimicrobial Agents
Citation Excerpt :
Among the major risk factors associated with antibacterial treatment failure include antibacterial drug resistance, which continues to increase worldwide, and the recently rising challenge of biofilm formation by biofilm-forming strains that shields susceptible bacteria from antimicrobials [1–3]. In this regard, the minimum inhibitory concentration (MIC) and the mutant prevention concentration (MPC), in vitro static parameters, have been used in several studies to assess the antibacterial activity of veterinary fluoroquinolones [4–6]. In averting the challenge in antibacterial treatment of biofilm-forming bacterial strains, the use of minimum biofilm eradication concentration (MBEC) is becoming popular, although it is still under pre-clinical investigation as it is difficult to achieve the concentration with current drug regimens [7,8].
The aim of the current study was to demonstrate and compare the impact of different pharmacokinetics of marbofloxacin, enrofloxacin and difloxacin on their antimicrobial effects, their killing and re-growth kinetics, and the population dynamics of Actinobacillus pleuropneumoniae clinical isolates in an in vitro dynamic model. Selected clinical isolates of A. pleuropneumoniae and three fluoroquinolones at a range of simulated AUC24/MIC ratios of multiple doses were investigated. At the same simulated AUC24/MIC ratios of the three fluoroquinolones, the killing re-growth profile and IE values (intensity of the antimicrobial effect) revealed strain- and fluoroquinolone-specific effects. For example, a 31% lower IE of difloxacin was observed in AppK5 (biofilm-former) than in AppK2 (biofilm-non-former) at the same AUC24/MIC ratio of 120h. In addition, losses in A. pleuropneumoniae susceptibility of both strains by the three fluoroquinolones were observed. AUC24/MPC ratios of 20.89 and 39.81 for marbofloxacin, 17.32 and 19.49 for enrofloxacin and 31.62 and 60.25 for difloxacin were estimated to be protective against the selection of AppK2 and AppK5 strain mutants, respectively. Integration of these in vitro data with published pharmacokinetics revealed the inadequacy of the conventional clinical doses of the three drugs to attain the above protective values for minimum biofilm eradication concentration (MBEC) and concentration to prevent growth of 90% of the mutant subpopulation (MPC90). In conclusion, the results suggest optimising doses could suffice for resistant mutants control, while for biofilm-forming strains combination with biofilm-disrupting agents to reduce the MBEC to achieve AUC/MBEC ratios within the possible dosing regimens is desired.
Effect of veterinary antibiotics on biogas and bio-methane production
2013, International Biodeterioration and Biodegradation
This work studied the effect of three classes of veterinary antibiotics (Ceftiofur, Danofloxacin and Micospectone: a combination of Spectinomycin and Lincomycin) that are used to treat the respiratory diseases of cows and pigs on anaerobic digestion. Three different doses of antibiotics were added to a pig slurry and tested in combination with two patterns of thermal treatment performed over various times.
During the anaerobic tests, such parameters as total biogas production and methane concentration in biogas were monitored. At the end of the anaerobic tests, antibiotic concentrations left in the slurries were detected. The results showed that Ceftiofur was the most degradable drug (approximately 70% of the initial content was degraded), while Danofloxacin and Lincomycin were less degradable (30–34% of the total initial content). The greatest inhibition of anaerobic digestion was observed with the drug association of Lincomycin and Spectinomycin (Micospectone), which presented the least physical degradability (heat treatment) and biological degradability.
Recommended articles (6)
Pathogen bacteria adhesion to skin mucus of fishes
Veterinary Microbiology, Volume 171, Issues 1–2, 2014, pp. 1-12
Fish are always in intimate contact with their environment; therefore they are permanently exposed to very vary external hazards (e.g. aerobic and anaerobic bacteria, viruses, parasites, pollutants). To fight off pathogenic microorganisms, the epidermis and its secretion, the mucus acts as a barrier between the fish and the environment. Fish are surrounded by a continuous layer of mucus which is the first physical, chemical and biological barrier from infection and the first site of interaction between fish's skin cells and pathogens. The mucus composition is very complex and includes numerous antibacterial factors secreted by fish's skin cells, such as immunoglobulins, agglutinins, lectins, lysins and lysozymes. These factors have a very important role to discriminate between pathogenic and commensal microorganisms and to protect fish from invading pathogens. Furthermore, the skin mucus represents an important portal of entry of pathogens since it induces the development of biofilms, and represents a favorable microenvironment for bacteria, the main disease agents for fish. The purpose of this review is to summarize the current knowledge of the interaction between bacteria and fish skin mucus, the adhesion mechanisms of pathogens and the major factors influencing pathogen adhesion to mucus. The better knowledge of the interaction between fish and their environment could inspire other new perspectives to study as well as to exploit the mucus properties for different purposes.
Effects of a blend of cinnamaldehyde, eugenol and capsicum oleoresin (CEC) on growth performance, nutrient digestibility, immune response and antioxidant status of growing ewes
Livestock Science, Volume 234, 2020, Article 103982
This study was conducted to evaluate the effects of a blend of cinnamaldehyde, eugenol and capsicum oleoresin (CEC) on growth performance, nutrient digestibility, immune response and antioxidant status of growing ewes. Fifty-four 4-month-old crossbred ewes (Dorper×Mongolian Sheep) with an initial body weight (BW) of 34.84±0.51kg were randomly assigned into three treatments with six replicates of each treatment and three ewes per replicate. The treatments were as follows: (1) CTR (control, no CEC added), (2) CEC50 (50mg CEC/kg of feed) and (3) CEC80 (80mg CEC/kg of feed). The experimental period lasted 60 days and was preceded by an adaption period of 15 days. The ADG were significantly greater (P=0.04) for ewes fed CEC80 diet than those fed CTR diet. The NDF apparent digestibility was higher (P=0.02) for ewes from CEC80 group compared to the CTR group. Ewes fed CEC had higher (P<0.05) plasma IGF-I, IgM and IL-10 concentrations and T-AOC than ewes fed CTR diet. The plasma CAT activity of ewes received CEC diets tended to be higher (P=0.09) than those fed CTR diet. Moreover, the plasma IgG concentration of CEC50 group was greater (P<0.01) than the CTR group. The results of this study demonstrate that supplementation of CEC at 180mg/kg feed was effective in promoting growth performance and nutrient digestion in growing ewes with stimulatory effects on their immune response and antioxidant status.
Biofilm formation in Haemophilus parasuis: relationship with antibiotic resistance, serotype and genetic typing
Research in Veterinary Science, Volume 97, Issue 2, 2014, pp. 171-175
Biofilms are surface-associated microbial communities, which are encased in self-synthesized extracellular environment. Biofilm formation may trigger drug resistance and inflammation, resulting in persistent infections. Haemophilus parasuis is the etiological agent of a systemic disease, Glässer's disease, characterized by fibrinous polyserositis, arthritis and meningitis in pigs. The purpose of this study was to examine the correlation between biofilm and antibiotic resistance among the clinical isolates of H. parasuis. In the present study, we tested biofilm-forming ability of 110 H. parasuis isolates from various farms using polystyrene microtiter plate assays. Seventy-three isolates of H. parasuis (66.4%) showed biofilm formation and most of them performed weak biofilm-forming ability (38/73). All isolates were tested for antimicrobial susceptibility to 18 antimicrobial agents by the broth microdilution method. H. parasuis isolates showed very high resistance (>90%) to sulfanilamide, nalidixic acid, and trimethoprim. Resistance to eight antibiotics such as penicillin (41.1% vs 8.1%), ampicillin (31.5% vs 8.1%), amoxicillin (28.8% vs 5.4%), gentamicin (46.6% vs 24.3%), cefazolin (19.2% vs 2.7%), doxycycline (19.2% vs 8.1%), cefotaxime (11% vs 2.7%), and cefaclor (13.7% vs 5.4%) was comparatively higher among biofilm producers than non-biofilm producers. Pulsed-field gel electrophoresis (PFGE) analyses could distinguish various isolates. Our data indicated that H. parasuis field isolates were able to form biofilms in vitro. In addition, biofilm positive strains had positive correlation with resistance to β-lactams antibiotics. Thus, biofilm formation may play important roles during H. parasuis infections.
Pharmacokinetics of oxytetracycline in broiler chickens following different routes of administration
The Veterinary Journal, Volume 208, 2016, pp. 96-98
The aim of this study was to determine the pharmacokinetics of oxytetracycline (OTC) in broiler chickens following intravenous (IV), intramuscular (IM), subcutaneous (SC) and oral (PO) administrations at a dose of 15 mg/kg bodyweight. Plasma concentrations of OTC were determined using liquid chromatography–tandem mass spectrometry and non-compartmental pharmacokinetic analysis was then conducted.
The absorption half-life time was 1.23 ± 0.36 h, 1.19 ± 0.52 h, and 0.49 ± 0.38 h after IM, SC and PO administration, respectively. The elimination half-life time was 27.41 ± 6.06 h, 10.23 ± 4.20 h, 7.83 ± 0.56 h, and 14.86 ± 9.23 h, and the mean residence time was 9.67 ± 1.7 h, 11.45 ± 1.76 h, 11.38 ± 0.59 h, and 10.37 ± 3.91 h after IV, IM, SC and PO administration, respectively. Bioavailability was 76.88 ± 12.90%, 92.20 ± 10.53% and 12.13 ± 4.56% after IM, SC and PO administration, respectively, which indicated that OTC is poorly absorbed from the gastrointestinal tract in broiler chickens.
Blue light-emitting diode photoinactivation inhibits edwardsiellosis in fancy carp (Cyprinus carpio)
Aquaculture, Volume 483, 2018, pp. 1-7
Although the use of blue light (400–500nm) to reduce bacterial pathogens in fish farms has various advantages over chemical microbicides, there has been little research on applications of blue light in aquatic organism disease management. The aims of this study were to verify the bactericidal effects of light conditions (light spectrum and intensity) on Edwardsiella piscicida demonstrate the efficacy of blue light irradiation in reducing edwardsiellosis in fancy carp, and analyze the potential harmful effects of blue light on carp.
E. piscicida at a concentration of 105CFUml−1 were exposed to 405 or 465nm light for an exposure time estimated to inactivate 99% of the bacteria. In vivo efficacy test of blue light emitting diodes (LEDs) was done using a cohabitation challenge in which infection rate and viable E. piscicida count in the rearing water were monitored. The potential harmful effects of the light conditions were investigated by observing histopathological changes in eye tissue, and gene expression of heat shock protein 70 and corticosteroid 11-beta-dehydrogenase isozyme 2 in kidney tissue. The percentage of E. piscicida inactivation resulting from various intensities of blue LED wavelengths demonstrated a strong correlation between light intensity and irradiation time. Furthermore, blue LED irradiation decreased the number of E. piscicida in rearing water as well as the proportion of infected fish. Histopathological examination revealed melanin granules (rod outer segment) and photoreceptors were temporarily thickened in retinas, but there were no significant differences between control and light irradiation groups after 28days of exposure. This study demonstrates that blue light irradiation is capable of inactivating E. piscicida and reducing its infection of fancy carp without causing adverse side-effects.
This study provides data on photoinactivation of blue LED light on the fish pathogen Edwardsiella piscicida, and the optimal conditions of light intensity and exposure time for inactivation. We also demonstrate that appropriate blue LED exposure reduced viable E. piscicida in rearing water and infection rates without causing adverse side-effects. The use of high-intensity narrow-spectrum blue LED light, without the addition of a photosensitizer, has great potential as an eco-friendly option for treating bacterial diseases in aquatic animals, and will help to reduce the use of antibiotics.
Antibiotic resistance of Vibrio harveyi isolated from seawater in Korea
Marine Pollution Bulletin, Volume 86, Issues 1–2, 2014, pp. 261-265
Vibrio harveyi is an opportunistic human pathogen that may cause gastroenteritis, severe necrotizing soft-tissue infections, and primary septicemia, with a potentially high rate of lethality. In this study, we isolated and characterized V. harveyi from seawater collected from the West Sea in Korea, including sites located near shellfish farms. For the initial isolation of putative V. harveyi, isolates were incubated on thiosulfate citrate bile salt sucrose agar plates for 24h, followed by selection of greenish colonies. Gram-negative and oxidase-positive colonies were subsequently confirmed by biochemical assays and the API 20E kit test system. Species-specific 16S rRNA and hemolysin genes were used to design V. harveyi-specific PCR primers. From 840 seawater samples, a total of 2 strains of V. harveyi were isolated from shellfish farm seawater. The two isolates were subjected to profiling against 16 antibiotics and found to be resistant to cephalothin, vancomycin, ampicillin, cefepime, cefotetan, and streptomycin.
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