Comparative quantification of the in vitro activity of veterinary fluoroquinolones (2023)

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.

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.

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.

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, AUC_0–24 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.

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 I_E values (intensity of the antimicrobial effect) revealed strain- and fluoroquinolone-specific effects. For example, a 31% lower I_E 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.

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.

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.

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.

The Veterinary Journal, Volume 208, 2016, pp. 96-98

Aquaculture, Volume 483, 2018, pp. 1-7

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.