Clinical efficacy and palatability of pradofloxacin 2.5% oral suspension for the treatment of bacterial lower urinary tract infections in cats

BACKGROUND: Pradofloxacin is a 3rd generation veterinary fluoroquinolone designed to restrict the emergence of antimicrobial resistance during therapy. HYPOTHESIS: Pradofloxacin 2.5% oral suspension is a safe, efficacious, and palatable treatment for bacterial urinary tract infections (UTI) in cats. ANIMALS: Seventy-eight cats presented with lower urinary tract signs and were positive on bacterial culture of urine. METHODS: Cats were allocated into 3 treatment groups depending on bacterial susceptibility results: pradofloxacin (n = 27), doxycycline (n = 23), or amoxicillin-clavulanic acid (n = 28). All antimicrobials were presented in palatable liquid form. Posttreatment urine specimens were collected after completion of the course of treatment and submitted for bacterial culture and sensitivity. Owners were questioned before and after treatment about their experiences with administering oral medication to their cats. RESULTS: Posttreatment urine culture was negative in all cats in the pradofloxacin group, but there were 3 treatment failures in each of the other groups. Owners' perceptions of the difficulty of administering oral medication to their cats was more positive posttreatment than pretreatment (P = .001; P < .001). There was no difference in palatability among the treatment groups (P > .05). CONCLUSIONS AND CLINICAL IMPORTANCE: We conclude that pradofloxacin 2.5% oral suspension is a highly effective and safe antimicrobial treatment for bacterial lower urinary tract infection in cats, and that the palatable formulation optimizes owner compliance. These findings make pradofloxacin a useful addition to the veterinary formulary.     

In vitro antimicrobial activity of orbifloxacin against Staphylococcus intermedius isolates from canine skin and ear infections

The objective of the study was to evaluate the in vitro activity of orbifloxacin against Staphylococcus intermedius strains isolated in France from canine skin and ear infections. The minimum inhibitory concentrations (MICs) of orbifloxacin against 240 field S. intermedius isolates (69 skin and 171 ear isolates) ranged from 0.016 to 8 mg l(-1), with MIC50 and MIC90 equal to 0.5 and 1 mg l(-1), respectively. Only one strain, a pyoderma isolate was resistant (MIC=8 mg l(-1)). Orbifloxacin was tested at different concentrations for killing rate against five isolates obtained from pyoderma cases and against a reference strain (Staphylococcus aureus ATCC 29213). Orbifloxacin expressed a concentration-dependent bactericidal activity against the S. aureus reference strain, but a time-dependent bactericidal activity against S. intermedius. Orbifloxacin induced bactericidal effect against the S. intermedius strains tested with concentrations equal to or two times MIC.     

Pharmacokinetics,pharmacodynamics and therapeutics of pradofloxacin in the dog and cat

Pradofloxacin is a third‐generation fluoroquinolone, licensed in the EU for use in a range of indications in the dog and cat and authorized more recently in the USA for one therapeutic indication (skin infections) in the cat. This review summarizes and appraises current knowledge on the physico‐chemical, pharmacological [pharmacokinetics (PK) and pharmacodynamics (PD)], safety and therapeutic properties of pradofloxacin in the target species. Pradofloxacin contains two centres of asymmetry and is the pure SS enantiomer. After oral dosing of tablets (dog) or tablets and oral suspension (cat), maximum plasma concentrations (C_max) are achieved in less than 3.0 h, and terminal half‐life is of the order of 5–10 h. Accumulation is slight or absent with once daily oral dosing. Free drug concentrations in plasma are in the range of 63–71% of total concentration. As for other fluoroquinolones, antibacterial activity is attributable to inhibition of bacterial replication at two sites, subunit A of topoisomerase II and topoisomerase IV. The antimicrobial spectrum includes gram‐negative and gram‐positive organisms, anaerobes, Mycoplasma spp. and some intracellular organisms (Rickettsia spp. and Mycobacterium spp.). The killing action is of the concentration‐dependent type. Pradofloxacin has high potency (low MIC values) in comparison with first‐ and second‐generation fluoroquinolones. Integration of in vivo PK and in vitro PD data provides values of C_max/MIC and area under plasma concentration–time curve (AUC_24 h)/MIC ratios predictive of good clinical efficacy against sensitive organisms, when administered at recommended dose rates. Clinical trial evaluation of pradofloxacin, in comparison with other authorized antimicrobial drugs, has demonstrated either noninferiority or superiority of pradofloxacin. Data indicating clinical and, in some instances, bacteriological cure have been reported: (i) in cats, for wound infections, abscesses, upper respiratory tract infections, conjunctivitis, feline infectious anaemia and lower urinary tract infections and (ii) in dogs, for wound infections, superficial and deep pyoderma, acute urinary tract infections and adjunctive treatment of infections of gingival and periodontal tissues. At clinical dose rates pradofloxacin was well tolerated in preclinical studies and in clinical trials. Among the advantages of pradofloxacin are (i) successful treatment of infections caused by strains resistant to some other fluoroquinolones, as predicted by PK/PD data, but depending on the specific MIC of the target strain and (ii) a reduced propensity for resistance development based on MPC measurements. The preclinical and clinical data on pradofloxacin suggest that this drug should commonly be the fluoroquinolone of choice when a drug of this class is indicated. However, the PK/PD data on pradofloxacin, in comparison with other fluoroquinolones, are not a factor that leads automatically to greater clinical efficacy.     

In vitro and in vivo pharmacodynamic properties of the fluoroquinolone ibafloxacin

The pharmacodynamic properties of a new veterinary fluoroquinolone antimicrobial agent, ibafloxacin, were evaluated. Minimal inhibitory concentrations (MIC), time-kill kinetics, postantibiotic effect (PAE) and postantibiotic subminimal inhibitory concentration effects (PA-SME) were determined against pathogenic canine Gram-negative and Gram-positive bacterial isolates from dermal, respiratory and urinary tract infections. The synergistic interactions between ibafloxacin and its main metabolite, 8-hydroxy-ibafloxacin were investigated. Finally, the efficacy of ibafloxacin was tested in in vivo canine infection models. Ibafloxacin had good activity against Pasteurella spp., Escherichia coli, Klebsiella spp., Proteus spp. and Staphylococcus spp. (MIC90=0.5 microg/mL), moderate activity against Bordetella bronchiseptica, Enterobacter spp. and Enterococcus spp. (MIC50=4 microg/mL) and low activity against Pseudomonas spp. and Streptococcus spp. The time-killing analysis confirmed that ibafloxacin was bactericidal with a broad spectrum of activity. The PAE and PA-SME were between 0.7-2.13 and 1-11.5 h, respectively. Finally, studies in dog models of wound infection and cystitis confirmed the efficacy of once daily oral ibafloxacin at a dosage of 15 mg/kg. Additional studies are needed to better define the importance of AUC/MIC (AUIC) and Cmax/MIC ratios on the outcome of fluoroquinolone therapy in dogs.     

Antibacterial activity of marbofloxacin. A new fluoroquinolone for veterinary use against canine and feline isolates

Marbofloxacin is a new fluoroquinolone developed exclusively for veterinary use. Minimum inhibitory concentrations of marbofloxacin were assessed for 816 recent isolates associated with canine or feline diseases. Marbofloxacin showed a broad spectrum of activity against gram-negative and gram-positive bacteria. In vitro rates of killing of marbofloxacin and enrofloxacin were compared against strains of Staphylococcus intermedius and Pasteurella multocida , and the results showed no marked difference between the two antibiotics. The duration of bactericidal activity was evaluated ex vivo in the urine of dogs and cats treated with marbofloxacin and lasted from 2 to 5 days after a single administration according to the dosages. Post-antibiotic effect durations were determined with Escherichia colt, PasteureUa multocida, Staphylococcus aureus and Staphylococcus intermedius and were found almost equal to those of enrofloxacin or ciprofloxacin. These results predict a great potential for marbofloxacin in the treatment of a wide range of diseases in dogs and cats.     

头孢喹诺对临床分离菌株抗菌活性研究

本研究旨在评价头孢喹诺对上海市养殖场临床分离菌株的体外抗菌作用,为头孢喹诺的临床使用提供参考依据。从上海市养殖场分离并鉴定大肠杆菌、沙门氏菌、金黄色葡萄球菌和链球菌各若干株,采用微量肉汤稀释法测定头孢喹诺对各菌株的最小抑菌浓度（MIC）、最小杀菌浓度（MBC）,推算MIC₅₀和MIC₉₀,并绘制头孢喹诺对这4种细菌的杀菌动力学曲线。头孢喹诺对金黄色葡萄球菌、链球菌、沙门氏菌和大肠杆菌的MIC₅₀分别为0.063、0.063、0.032、0.125 μg/mL,MIC₉₀分别为0.125、0.125、0.125、0.25 μg/mL;在很小的浓度变化范围内头孢喹诺能够快速抑菌,在抑菌浓度为1倍或2倍MIC时,24 h内能杀灭金黄色葡萄球菌、大肠杆菌或链球菌、沙门氏菌。头孢喹诺对上述几种临床分离细菌具有很强的抑菌效果和杀菌活性。     

Susceptibility of rapidly growing mycobacteria and Nocardia isolates from cats and dogs to pradofloxacin

Rapidly growing mycobacteria (RGM) and Nocardiae can cause severe or refractory infections in cats and dogs. Prolonged antibacterial therapy is required to cure these infections. As fluoroquinolones have been used in combination therapy for treating RGM infections, isolates from the Mycobacterium smegmatis cluster (n=64), Mycobacterium fortuitum cluster (n=17), and M. mageritense cluster (n=2), collected from feline and canine patients, underwent susceptibility testing to pradofloxacin. The MIC(50), MIC(90) and tentative epidemiological cut-off (ECOFF) values as determined by microbroth dilution susceptibility testing that inhibited growth of the M. smegmatis and M. fortuitum clusters were 0.063, 0.125 and ≤ 0.25; and 0.125, 0.250 and ≤ 1.0 μg/mL, respectively. E-Test results showed similar trends but MICs were lower than those for microbroth dilution. In summary, pradofloxacin demonstrated effective in vitro activity against RGM isolates. Additionally, veterinary isolates of Nocardia nova (n=18), Nocardia farcinica (n=3) and Nocardia cyriacigeorgica (n=1) underwent microbroth dilution testing to ciprofloxacin, enrofloxacin and pradofloxacin. The MIC(50) and MIC(90) of pradofloxacin, ciprofloxacin and enrofloxacin that inhibited growth of Nocardia nova isolates were 2 (4), 8 (16), 16 (32) μg/mL, respectively. The tentative ECOFF values for pradofloxacin and ciprofloxacin were 32 μg/mL and for enrofloxacin 64 μg/mL. The MIC or MIC range for the three N. farcinica isolates of pradofloxacin, ciprofloxacin and enrofloxacin were 0.25-0.5, 2 and 2 μg/mL and for the single N. cyriacigeorgica isolate were 1, 4 and 4 μg/mL, respectively. On the basis on these results, fluoroquinolones appear to have limited therapeutic potential for most Nocardia infections.     

Comparative in vitro activity of three cephalosporins against Staphylococcus aureus isolated from bovine mastitis

This report compares the in vitro activity of three cephalosporins (cephalothin, cefoxitin and ceftriaxone) against 57 Staphylococcus aureus strains isolated from cows with clinical mastitis on the basis of the minimal inhibitory (MIC) and minimal bactericidal concentrations (MBC). The majority of the S aureus strains showed resistance to cefoxitin and ceftriaxone and sensitivity to cephalothin. The highest MICs and MBCs were found for cefoxitin and ceftriaxone. Antimicrobial tolerance (MBC/MIC greater than or equal to 32:1) was observed in relation to cephalothin and ceftriaxone. The data suggest that these cephalosporins may not be effective for the treatment of staphylococcal bovine mastitis. The precise definition of their antimicrobial efficacies requires more detailed in vitro and in vivo studies.     

In vitro susceptibilities of Leptospira spp. and Borrelia burgdorferi isolates to amoxicillin, tilmicosin, and enrofloxacin

Antimicrobial susceptibility testing was conducted with 6 different spirochetal strains (4 strains of Leptospira spp. and 2 strains of Borrelia burgdorferi) against 3 antimicrobial agents, commonly used in equine and bovine practice. The ranges of MIC and MBC of amoxicillin against Leptospira spp. were 0.05-6.25 µg/ml and 6.25-25.0 µg/ml, respectively. And the ranges of minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of amoxicillin against B. burgdorferi were 0.05-0.39 µg/ml and 0.20-0.78 µg/ml, respectively. The ranges of MIC and MBC of enrofloxacin against Leptospira spp. were 0.05-0.39 µg/ml and 0.05-0.39 µg/ml, respectively. Two strains of B. burgdorferi were resistant to enrofloxacin at the highest concentration tested for MBC (≥100 µg/ml). Therefore, the potential role of tilmicosin in the treatment of leptospirosis and borreliosis should be further evaluated in animal models to understand whether the in vivo studies will confirm in vitro results. All spirochetal isolates were inhibited (MIC) and were killed (MBC) by tilmicosin at concentrations below the limit of testing (≤0.01 µg/ml).     

Comparative activity of pradofloxacin and marbofloxacin against coagulase‐positive staphylococci in a pharmacokinetic–pharmacodynamic model based on canine pharmacokinetics

Körber‐Irrgang, B., Wetzstein, H.‐G., Bagel‐Trah, S., Hafner, D., Kresken, M. Comparative activity of pradofloxacin and marbofloxacin against coagulase‐positive staphylococci in a pharmacokinetic–pharmacodynamic model based on canine pharmacokinetics. J. vet. Pharmacol. Therap.  35 , 571–579. Pradofloxacin (PRA), a novel veterinary 8‐cyano‐fluoroquinolone (FQ), is active against Staphylococcus pseudintermedius, the primary cause of canine pyoderma. An in vitro pharmacokinetic–pharmacodynamic model was used to compare the activities of PRA and marbofloxacin (MAR) against three clinical isolates of S. pseudintermedius and reference strain Staphylococcus aureus ATCC 6538. Experiments were performed involving populations of 10¹⁰ CFU corresponding to an inoculum density of approximately 5 × 10⁷ CFU/mL. The time course of free drug concentrations in canine serum was modelled, resulting from once daily standard oral dosing of 3 mg of PRA/kg and 2 mg of MAR/kg. In addition, experimentally high doses of 6 mg of PRA/kg and 16 mg of MAR/kg were tested against the least susceptible strain. Viable counts were monitored over 24 h. At concentrations associated with standard doses, PRA caused a faster and more sustained killing than MAR of all strains. The ratios of free drug under the concentration–time curve for 24 h over MIC and the maximum concentration of free drug over MIC were at least 90 and 26, and 8.5 and 2.1 for PRA and MAR, respectively. At experimentally high doses, PRA was superior to MAR in terms of immediate killing. Subpopulations with reduced susceptibility to either FQ did not emerge. We conclude that PRA is likely to be an efficacious therapy of canine staphylococcal infections.     

Pharmacodynamics of ibafloxacin in micro-organisms isolated from cats

The pharmacodynamic properties of ibafloxacin were investigated in micro-organisms isolated from cats. Minimal inhibitory concentrations (MIC) of ibafloxacin (racemate, R- and S-enantiomers) and its metabolites (7-hydroxy- and 8-hydroxy-ibafloxacin) and time-kill kinetics were determined against Gram-negative and Gram-positive bacteria isolated from dermal and respiratory and urinary tract infections in cats. Racemic ibafloxacin has a broad spectrum of bactericidal activity against Gram-negative and some Gram-positive bacteria. Escherichia coli and Pasteurella, Klebsiella and Staphylococcus spp. are commonly isolated from feline infections and all are susceptible to ibafloxacin (MIC90 < or = 0.5 microg/mL), whereas Pseudomonas aeruginosa, Proteus mirabilis and Streptococcus spp. are considered intrinsic resistant. Microbiological activity resides primarily in the S-enantiomer of ibafloxacin whereas the R-enantiomer is less active. Killing curves using concentrations of racemic ibafloxacin and 8-hydroxy-ibafloxacin, which are representative of the in vivo situation observed in cats, showed at least 99.9% reduction in viable bacterial isolates from feline clinical samples over 24 h. Bacterial eradication was achieved in cats with Cmax/MIC and AUC/MIC values much lower than the target values previously established in man and laboratory animals. Additional studies in dogs and cats are necessary to define more clearly the surrogate markers of antibacterial activity (i.e. Cmax/MIC, AUC/MIC ratios), which are associated with a good clinical response.     

Antibacterial activity of cefquinome against equine bacterial pathogens

Cefquinome is known for its use as an antibacterial drug in cattle and pigs. The objective of this study was to evaluate the antibacterial activity of cefquinome against equine pathogenic bacteria. The minimum inhibitory concentration (MIC) of cefquinome was determined for a total of 205 strains, which had recently been isolated in Europe from diseased horses (respiratory infection, foal septicaemia). The bactericidal activity was tested against 19 strains using the time killing method. The post-antibiotic effect (PAE) and post-antibiotic sub-MIC effect (PA SME) were determined against 12 strains. Cefquinome showed high activity against Actinobacillus equuli and streptococci (MIC(90) of 0.016 and 0.032microg/mL), Enterobacteriaceae (MIC(90)=0.125microg/mL) and staphylococci (MIC(90)=0.5microg/mL). The activity was limited against Rhodococcus spp. and Pseudomonas spp. Cefquinome was shown to be a time dependent bactericidal antibiotic against the target pathogens, killing occurring at a concentration close to the MIC. A PAE of 0.5-10h was calculated against streptococci whereas no PAE was observed for Escherichia coli. A longer PA SME was determined for streptococci (3.3 to >24h with a killing effect) and E. coli (0.5-13.9h). Cefquinome was shown to have a broad spectrum of activity which covers many equine pathogens.     

Efficacy of pradofloxacin in cats with feline upper respiratory tract disease due to Chlamydophila felis or Mycoplasma infections

BACKGROUND: Upper respiratory tract disease (URTD) of cats is caused by a number of pathogens, including Chlamydophila felis and Mycoplasma spp. For effective treatment of both infections, doxycycline and enrofloxacin are recommended, but adverse effects limit their use in cats. HYPOTHESIS: That the fluoroquinolone pradofloxacin is effective against C. felis and Mycoplasma infection in cats with URTD or conjunctivitis. ANIMALS: Thirty-nine cats with signs of URTD or conjunctivitis. METHODS: Placebo-controlled, double-blind clinical trial. Cats were randomly entered into 1 of 2 treatment groups: treated PO with either 5 mg/kg pradofloxacin q24h or 5 mg/kg doxycycline q12h for 42 consecutive days. Changes in health status and clinical scores were evaluated. The presence of C. felis and Mycoplasma spp. was determined by quantitative polymerase chain reaction (PCR) and nested PCR of conjunctival swabs, respectively. RESULTS: At the beginning of the study, C. felis and Mycoplasma spp. were detected in 23 and 20 cats, respectively. Cats of both groups responded rapidly with a marked improvement in clinical signs within the 1st week. During treatment with either drug, C. felis DNA copy number declined quickly. Complete elimination of Mycoplasma spp. was achieved in both groups; however, whereas all cats receiving doxycycline eliminated C. felis, 4 cats treated with pradofloxacin remained PCR-positive. CONCLUSION AND CLINICAL IMPORTANCE: This study demonstrates that both pradofloxacin and doxycycline have good efficacy against C. felis and Mycoplasma spp., resulting in a marked improvement of clinical signs. However, C. felis DNA remained in some cats after treatment with pradofloxacin, suggesting that infection might not have been eliminated.     

Dog-bite wounds: bacteriology and treatment outcome in 37 cases

Bite wounds in 37 dogs were prospectively evaluated. Ninety-five percent of animals presented within 12 hours of injury. The most common wound locations were neck, limbs, head, chest, shoulder region, and abdomen. Eighty-six percent had wounds to multiple locations. Fifty-seven percent of wounds were Class 4 (i.e., most severe). Based on results of all samples, 65% had positive aerobic cultures, 15% had positive anaerobic cultures, and 33% had negative cultures. The most commonly isolated aerobic bacteria were Staphylococcus intermedius, Enterococcus spp., Staphylococcus coagulase negative, and Escherichia coli. Most common anaerobic isolates were Bacillus spp., Clostridium spp., and Corynebacterium spp. Severe bite wounds had a high rate of bacterial contamination at presentation. No single antibiotic or antibiotic combination was effective against all bacteria that were cultured.     

苦荞麦中芦丁提取及体外抑菌活性研究

采用乙醇回流法提取苦荞麦中的芦丁,并进行TLC检测、紫外光谱和红外光谱检测。将芦丁对两种供试菌进行体外最小抑制浓度(MIC)、最低杀菌浓度(MBC)、半数抑菌浓度(IC50)测定。结果表明,其对大肠埃希氏杆菌、金黄色葡萄球菌的MIC分别为0.40mg/mL和0.20mg/mL;MBC分别为0.50mg/mL和0.20mg/mL;IC50分别为0.2605mg/mL和0.1607mg/mL。     

肉桂醛体外抑制奶牛乳房炎主要致病菌的研究

研究天然化合物肉桂醛对奶牛乳房炎主要致病菌——大肠杆菌、金黄色葡萄球菌和链球菌的抑菌效果。采用试管二倍稀释法测得肉桂醛对奶牛乳房炎主要致病菌金黄色葡萄球菌和标准金黄色葡萄球菌的体外最小抑菌浓度(MIC)分别为3.2 mmol/L和1.6 mmol/L;链球菌1.6 mmol/L;大肠杆菌和标准大肠杆菌6.4 mmol/L和3.2 mmol/L,且能完全抑制这三种菌的生长。肉桂醛的最小杀菌浓度(MBC)金黄色葡萄球菌和标准金黄色葡萄球菌分别为25.6 mmol/L和12.8 mmol/L;链球菌12.8 mmol/L;大肠杆菌和标准大肠杆菌25.6 mmol/L和12.8 mmol/L;在7 h内能有效杀灭这三种菌,肉桂醛对奶牛乳房炎主要致病菌有抑菌和杀菌能力,是一种潜在的奶牛乳房炎的临床治疗药物。     

In vitro activity of difloxacin against canine bacterial isolates.

The in vitro activity of difloxacin against canine bacterial isolates from clinical cases was studied in the United States and The Netherlands. Minimal inhibitory concentrations (MIC), the postantibiotic effect, the effect of pH on antimicrobial activity, and the bacterial killing rate tests were determined according to standard techniques. The MICs of American and Dutch isolates agreed in general. The MICs of the American gram-negative isolates ranged from 0.06 to 2.0 microg/ml, and the MICs of the Dutch gram-negative isolates ranged from 0.016 to 8.0 microg/ml. A few European strains of Proteus mirabilis and Klebsiella pneumoniae had relatively high MICs. Bordetella bronchiseptica also was less susceptible to difloxacin. The MICs of the American gram-positive cocci ranged from 0.125 to 4.0 microg/ml, and the MICs of Dutch isolates ranged from 0.125 to 2.0 microg/ ml. Difloxacin induced a concentration-dependent postantibiotic effect that lasted 0.2-3 hours in cultures with Escherichia coli, Staphylococcus intermedius, Streptococcus canis, Proteus spp., and Klebsiella pneumoniae. There was no postantibiotic effect observed against canine Pseudomonas aeruginosa. Decreasing the pH of the medium increased the MIC of Proteus mirabilis for difloxacin. The MICs of Escherichia coli and Klebsiella pneumoniae were lowest at neutral pH and were slightly increased in acid or alkaline media. At a neutral pH, most tested bacterial species were killed at a difloxacin concentration of 4 times the MIC. Similar results were obtained when these same bacteria were tested against enrofloxacin. A Klebsiella pneumoniae strain in an acidic environment was readily killed at difloxacin or enrofloxacin MIC, but at neutral pH the drug concentration had to be raised to 4 times the MIC for a bactericidal effect. After 24 hours of incubation at pH 7.1, difloxacin and enrofloxacin had similar bactericidal activity for all bacteria tested except Staphylococcus intermedius. Against S. intermedius, difloxacin was more bactericidal than enrofloxacin.     

Kill kinetics of the cephalosporin antibiotics cephalexin and cefuroxime against bacteria of veterinary importance

Kill kinetic studies for two cephalosporin antibiotics, cephalexin and cefuroxime were carried out against veterinary strains of Escherichia coli, Pasteurella multocida, Streptococcus suis, Erysipelothrix rhusiopathiae and a laboratory culture of Staphylococcus aureus. In more than 90 per cent of cases a kill of more than 99 per cent was achieved within four hours of antibiotic treatment at concentrations of 2 or 4 micrograms/ml. Although cefuroxime was effective at lower concentrations than cephalexin the rates of kill of the two antibiotics were comparable. The results are discussed in relation to in vivo dosage regimens.     

Evaluation of the sensititre method adapted for antimicrobial drug susceptibility testing in veterinary medicine

The Sensititre method specially designed for MIC determinations of animal pathogenic bacteria is evaluated. The MIC values of 251 clinical isolates belonging to different genera were determined by a modified Sensititre method and by a standard agar dilution method. Of all the compared MIC values, 90.7% were within one doubling dilution and 97.7% within two doubling dilutions. For ampicillin, oxacillin, chloramphenicol, erythromycin and nitrofurantoin more than 96% of the MIC pairs compared with less than 90% for neomycin, streptomycin, tetracycline and trimethoprim-sulpha-methoxazole were within one doubling dilution. With regard to organisms, the best agreement was for pasteurellae and the lowest for streptococci of which 95.8% and 87%, respectively, were within one doubling dilution. The Sensititre method modified for use in veterinary clinical bacteriology was found to be a reliable method for MIC determinations of common animal pathogens.     

七种常用渔药及组合对罗非鱼致病性海豚链球菌的抗菌试验

探讨了7种常用抗菌渔药对罗非鱼致病性海豚链球菌的体内外抗菌作用.采用二倍稀释法测定了7种渔药对致病菌的最低抑菌浓度(MIC)和最低杀菌浓度(MBC);在初筛基础上以MIC为单位,1×MIC、5×MIC、10×MIC和20×MIC下平板抑菌圈直径为参数,分别比较所筛选5种药物抗菌效果并优化最佳参数;利用优化的最佳参数比较5种药物单独用药与联合用药对海豚链球菌的抑菌效果;并通过拌饵投喂给药方式对罗非鱼进行5种药物治疗性给药试验.结果表明,抗菌先锋对海豚链球菌的MIC和MBC最小,分别为6.4、12.8μg/mL,其次是伯乐立康,均为12.8μg/mL;而鱼康和肠炎烂鳃灵即使在1638.4μg/mL下也无抗菌效果.5倍MIC下抑菌圈直径为本试验筛选抗菌药物的最佳参数.5MIC时,海豚链球菌对伯乐立康和抗菌先锋敏感,对菌必清、菌毒康和海鱼安中度敏感.菌毒康与海鱼安的联合抗菌效果最佳.鱼体内抗菌试验结果表明,抗菌先锋和伯乐立康的治疗有效率超过75%,达到了理想的治疗效果,是防治罗非鱼海豚链球菌病的首选药物.