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ABSTRACT: This study describes trends in the use and indications for prescriptions of antimicrobial agents in the Danish pig production in the period between 2002 and 2008 and is the first description of a complete prescription pattern for one animal species in an entire country. Data on all prescription for pigs in Denmark were retrieved from the VetStat database. Antimicrobial use was measured in defined animal daily doses (ADD) for the specific age-group and in ADD(kg) as a measure of amounts used. According to the results of the ADD(kg) data, 26% of all antimicrobials were prescribed for sows, 38% for weaner pigs, and 33% for finisher pigs. In weaner and finisher pigs, gastrointestinal infections accounted for 74-83% and 56-65% of the use, while respiratory infections accounted for 9-17% and 18-24%, respectively. From 2002 to 2008, prescription for respiratory disease increased by 145% for sows/piglets, by 141% for weaning pigs, and by 81% for finisher pig. The most commonly used class of antibiotics was tetracycline for all age-groups, replacing the previously used macrolide/lincosamide group. The use of pleuromutilin increased in 2008 to the level of macrolides. In sow/piglets, the second most used class was penicillins. The switch in choice of antimicrobial classes prescribed seems to be related primarily to changes in the price of the drugs.
Journal of Veterinary Pharmacology and Therapeutics 05/2011; 35(1):33-46. · 1.18 Impact Factor
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ABSTRACT: We recently reported a phenotypic association between reduced susceptibility to zinc and methicillin resistance in Staphylococcus aureus CC398 isolates from Danish swine (F. M. Aarestrup, L. M. Cavaco, and H. Hasman, Vet. Microbiol. 142:455-457, 2009). The aim of this study was to identify the genetic determinant causing zinc resistance in CC398 and examine its prevalence in isolates of animal and human origin. Based on the sequence of the staphylococcal cassette chromosome mec (SCCmec) element from methicillin-resistant S. aureus (MRSA) CC398 strain SO385, a putative metal resistance gene was identified in strain 171 and cloned in S. aureus RN4220. Furthermore, 81 MRSA and 48 methicillin-susceptible S. aureus (MSSA) strains, isolated from pigs (31 and 28) and from humans (50 and 20) in Denmark, were tested for susceptibility to zinc chloride and for the presence of a putative resistance determinant, czrC, by PCR. The cloning of czrC confirmed that the zinc chloride and cadmium acetate MICs for isogenic constructs carrying this gene were increased compared to those for S. aureus RN4220. No difference in susceptibility to sodium arsenate, copper sulfate, or silver nitrate was observed. Seventy-four percent (n = 23) of the animal isolates and 48% (n = 24) of the human MRSA isolates of CC398 were resistant to zinc chloride and positive for czrC. All 48 MSSA strains from both human and pig origins were found to be susceptible to zinc chloride and negative for czrC. Our findings showed that czrC is encoding zinc and cadmium resistance in CC398 MRSA isolates, and that it is widespread both in humans and animals. Thus, resistance to heavy metals such as zinc and cadmium may play a role in the coselection of methicillin resistance in S. aureus.
Antimicrobial Agents and Chemotherapy 09/2010; 54(9):3605-8. · 4.84 Impact Factor
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ABSTRACT: Multidrug-resistant (MDR) Salmonella Concord has been associated with adoptees from Ethiopia. In 2009, Denmark saw an increase in MDR S. Concord infections among Ethiopian adoptees.
Euro surveillance: bulletin europeen sur les maladies transmissibles = European communicable disease bulletin 01/2010; 15(23). · 6.15 Impact Factor
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ABSTRACT: A classification system for plasmids isolated from enterococci and other Gram-positive bacteria was developed based on 111 published plasmid sequences from enterococci and other Gram-positive bacteria; mostly staphylococci. Based on PCR amplification of conserved areas of the replication initiating genes (rep), alignment of these sequences and using a cutoff value of 80% identity on both protein and DNA level, 19 replicon families (rep-families) were defined together with several unique sequences. The prevalence of these rep-families was tested on 79 enterococcal isolates from a collection of isolates of animal and human origin. Difference in prevalence of the designed rep-families were detected with rep(9) being most prevalent in Enterococcus faecalis and rep(2) in Enterococcus faecium. In 33% of the tested E. faecium and 32% of the tested E. faecalis no positive amplicons were detected. Furthermore, conjugation experiments were performed obtaining 30 transconjugants when selecting for antimicrobial resistance. Among them 19 gave no positive amplicons indicating presence of rep-families not tested for in this experimental setup.
Journal of microbiological methods 10/2009; 80(1):25-43. · 2.43 Impact Factor
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ABSTRACT: A survey for methicillin-resistant Staphylococcus aureus (MRSA) in finishing pig holdings was carried out in Italy in 2008. MRSA isolates were characterised by spa-, MLST-, SCCmec- and antimicrobial susceptibility typing. A prevalence of 38% (45/118, 95% CI 29.4-46.9%) positive holdings was observed. Eleven different spa-types were found among 102 MRSA isolates, clustering in lineages associated with farm animals (ST398, ST9, ST(CC)97 in 36 holdings) and humans (ST1, 7 holdings). Nine (7.6%) holdings were positive for two, three or four different and unrelated spa-types in various combinations. ST398 was the most prevalent lineage (33 positive holdings). The most prevalent spa-type was t899 (ST398), detected in 22 positive holdings. Three novel spa-types (t4794 of ST9; t4795 of ST97; t4838 of ST398) were detected. Ten holdings were positive for spa-type t1730, that proved to be a new single-locus variant of ST97, within the CC97 (ST1476). The most prevalent SCCmec was Type V (79 isolates), while Type IVb was found in 10 isolates. None of the isolates was positive for Panton-Valentine Leukocidin, while most of the t127 and t1730 isolates, one t4794, one t4795, and one t2922 were positive for LukE-LukD genes. All 64 antimicrobial susceptibility tested isolates were resistant to tetracyclines, with high resistance rates to trimethoprim (68.8%), erythromycin (60.9%), and ciprofloxacin (35.4%). All t127, ST1 isolates were resistant to tetracycline-ciprofloxacin-erythromycin. This survey provides the first report of MRSA ST1 and ST(CC)97 among pigs and the first report of MRSA ST9 from pigs in Europe. The presence of human-associated CA-MRSA (t127, ST1, SCCmec type V) in 6% holdings surveyed can represent an additional MRSA reservoir for infections in humans.
Veterinary Microbiology 10/2009; 142(3-4):361-6. · 3.33 Impact Factor
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ABSTRACT: Methicillin-resistant S. aureus (MRSA) of clonal complex 398 (CC398) is emerging globally among production animals such as cattle, pigs and poultry as well as among humans. However, little is known about the prevalence of CC398 among methicillin sensitive S. aureus (MSSA) or the relative clonal distribution of S. aureus isolated from these three animal reservoirs. To study this, we have analyzed a random sample of S. aureus consisting of 296 epidemiologically unrelated isolates from infections and colonisation of pigs, cattle and poultry. These were examined and compared by spa and multi-locus sequence typing (MLST) and the result was compared to the most common spa types found among human blood isolates. Little overlap in spa types was seen between isolates from the three animal reservoirs or between animals and humans. Most of the porcine isolates had the spa types t034 (CC398), t1333 (CC30) and t337 (CC9), while the bovine isolates mainly had spa types t518 (CC50), t524 (CC97) and t529 (CC151). None of these spa types are common among human blood isolates in Denmark. Surprisingly, almost all of the poultry isolates (96%) belonged to CC5 (spa types t002 and t306), which is also known to be commonly found among human blood isolates and subsequent pulsed-field gel electrophoresis (PFGE) analysis identified indistinguishable PFGE patterns among a poultry isolate and selected human isolates. In conclusion, strains of MSSA CC398 were commonly present in pigs but not present at all in the other reservoirs tested.
Veterinary Microbiology 09/2009; 141(3-4):326-31. · 3.33 Impact Factor
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ABSTRACT: The phenotypic expression of haemolysins and the presence of genes encoding a and β-haemolysin were determined in 105 Staphylococcus aureus isolates from bovine mastitis, 100 isolates from the nostrils of healthy humans, and 60 isolates from septicaemia in humans. Furthermore, the possible change in expression of haemolysins after subcultivation in human and bovine blood and milk was studied in selected isolates. α-haemolysin was expressed phenotypically in 39 (37%) of the bovine isolates, in 59 (59%) of the human carrier isolates, and in 40 (67%) of the isolates from septicaemia. β-haemolysin was expressed in 76 (72%) bovine, 11 (11%) carrier, and 8 (13%) septicaemia isolates. Significantly more bovine than human isolates expressed β-haemolysin and significantly fewer expressed α-haemolysin. Genotypically, the gene encoding a-haemolysin was detected in all isolates. A significant difference in the prevalence of the gene encoding β-haemolysin between the bovine (96%), human carrier (56%) and isolates from septicaemia (57%) was found. Of the bovine isolates, 75% of those carrying the gene encoding β-haemolysin expressed β-haemolysin phenotypically, whereas only 20% of the carrier isolates and 24% of the septicaemia isolates did so. No change in expression of haemolysins could be observed after subcultivation of bovine isolates in human blood and milk. After 5 to 10 subcultures in bovine blood and 1 to 4 in bovine milk, 9 of 10 human isolates originally phenotypically β-haemolysin negative initiated the expression of β-haemolysin. This study showed that a larger proportion of S. aureus of bovine origin carry the β-haemolysin gene compared to isolates from humans. Furthermore, a larger number of the isolates of bovine origin carrying the β-haemolysin gene express this gene phenotypically compared to isolates of human origin.
Apmis 08/2009; 107(1‐6):425 - 430. · 1.99 Impact Factor
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ABSTRACT: Fluoroquinolone resistance in members of the Enterobacteriaceae family is mostly due to mutations in the quinolone resistance-determining regions of the topoisomerase genes. However, transferable genes encoding quinolone resistance have recently been described. The current methods for susceptibility testing are not adapted to the detection of new resistance determinants, which confer low levels of resistance. The aim of this study was to compare the ability of the screening of the different quinolones by disk diffusion assays and MIC determinations to detect fluoroquinolone resistance. Sixty-nine Escherichia coli strains and 62 Salmonella strains, including strains fully susceptible to quinolones, nalidixic acid-resistant strains, strains with resistance to fluoroquinolones (resistant to nalidixic acid), and strains showing low-level resistance to fluoroquinolones conferred by transferable quinolone resistance genes, including qnrA, qnrB, qnrS, and aac(6')Ib-cr, were selected. Disk diffusion assays and MIC determinations by the agar dilution method were performed, according to CLSI standards, with nalidixic acid, flumequine, oxolinic acid, ciprofloxacin, enrofloxacin, marbofloxacin, norfloxacin, ofloxacin, and levofloxacin. The MIC of levofloxacin was determined by an Etest. The results showed a trimodal distribution of the MICs for both E. coli and Salmonella. The MIC distributions for the isolates varied with the compounds tested. Screening for nalidixic acid resistance by MIC testing or disk diffusion assay was not efficient for the detection of some of the isolates carrying qnr and aac(6')Ib-cr. Transferable resistance genes would best be detected by testing for the MIC of ciprofloxacin or norfloxacin, as testing for the MICs of the other compounds would fail to detect isolates carrying aac(6')Ib-cr because the enzyme produced is able to reduce the activities of these two compounds only due to their chemical structures. In conclusion, screening with nalidixic acid is efficient for the detection of mutants, but it is not so efficient for the detection of qnr and aac(6')Ib-cr. Detection would be maximized by screening with either ciprofloxacin or norfloxacin by both MIC determination and disk diffusion assays. Furthermore, a low concentration of ciprofloxacin (1 microg) in the disks seemed to increase the sensitivity of the disk diffusion assay.
Journal of clinical microbiology 08/2009; 47(9):2751-8. · 4.16 Impact Factor
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ABSTRACT: In a previous study, four Salmonella isolates from humans in the Henan province of China showed reduced susceptibility to ciprofloxacin (MIC, 0.125 to 0.25 microg/ml) but were susceptible to nalidixic acid (MIC, 4 to 8 microg/ml). All isolates were negative for known qnr genes (A, B, and S), aac(6')Ib-cr, and mutations in gyrA and parC. Plasmid DNA was extracted from all four isolates and transformed into Escherichia coli TG1 and DH10B cells by electroporation, and transformants were selected on 0.06 microg/ml ciprofloxacin containing brain heart infusion agar plates. Resistance to ciprofloxacin could be transferred by electroporation, and a similar 4,270-bp plasmid was found in all transformants. By sequence analysis, the plasmid was found to carry an open reading frame that had similarities to other qnr genes and that encoded a 214-amino-acid pentapeptide repeat protein. This gene, designated qnrD, showed 48% similarity to qnrA1, 61% similarity to qnrB1, and 41% similarity to qnrS1. Further subcloning of the qnrD coding region into the constitutively expressed tetA gene of vector pBR322 showed that the gene conferred an increase in the MIC of ciprofloxacin by a factor of 32 (from an MIC of 0.002 to an MIC of 0.06 microg/ml). For comparison, qnrA1 and qnrS1 were also subcloned into pBR322 and transformed into DH10B cells, conferring MICs of 0.125 and 0.5 microg/ml, respectively. A phylogenetic analysis of all known qnr sequences was performed and showed that qnrD was more closely related to the qnrB variants but formed an independent cluster. To our knowledge, this is the first description of this qnrD gene.
Antimicrobial Agents and Chemotherapy 12/2008; 53(2):603-8. · 4.84 Impact Factor
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ABSTRACT: Extended-spectrum beta-lactamases (ESBLs), mainly of the CTX-M family, have been associated with Escherichia coli strains of animal origin in Europe. An in vivo experiment was performed to study the effects of veterinary beta-lactam drugs on the selection and persistence of ESBL-producing E. coli in the intestinal flora of pigs. Twenty pigs were randomly allocated into three treatment groups and one control group. All pigs were inoculated intragastrically with 10(10) CFU of a nalidixic acid (NAL)-resistant mutant derived from a CTX-M-1-producing E. coli strain of pig origin. Treatment with amoxicillin, ceftiofur, or cefquinome according to the instructions on the product label was initiated immediately after bacterial inoculation. Feces were collected from the rectum before inoculation and on days 4, 8, 15, 22, and 25 after the start of treatment. The total and resistant coliforms were counted on MacConkey agar with and without cefotaxime (CTX). Furthermore, MacConkey agar with CTX and NAL was used to count the number of CFU of the inoculated strain. Significantly higher counts of CTX-resistant coliforms were observed in the three treatment groups than in the control group for up to 22 days after the discontinuation of treatment. Ceftiofur and cefquinome exerted larger selective effects than amoxicillin, and the effects persisted beyond the withdrawal times recommended for these cephalosporins. The inoculated strain was detected in only nine animals on day 25. The increase in the number of CTX-resistant coliforms was mainly due to the proliferation of indigenous CTX-M-producing strains and the possible emergence of strains that acquired CTX-M genes by horizontal transfer. The study provides evidence that the cephalosporins used in pig production select for CTX-M-producing E. coli strains. Their use in animals should be carefully considered in view of the critical importance of cephalosporins and the zoonotic potential of ESBL-producing bacteria.
Antimicrobial Agents and Chemotherapy 10/2008; 52(10):3612-6. · 4.84 Impact Factor
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Journal of Antimicrobial Chemotherapy 06/2008; 62(3):632-4. · 5.07 Impact Factor
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ABSTRACT: This study describes the characterisation by pulsed-field gel electrophoresis (PFGE), multilocus variable number tandem repeat analysis (MLVA) typing and antimicrobial resistance profiles of 35 Salmonella enterica serovar Typhimurium isolates, mostly from infections in children who acquired an infection outside hospitals in the Gomel region of Belarus. Thirty-one isolates were highly similar according to PFGE and MLVA typing, were multidrug-resistant, including resistance to ceftiofur, and harboured the bla(CTX-M-5) gene. These results indicate that a common source may have been responsible for most of the infections.
Clinical Microbiology and Infection 11/2007; 13(10):1030-3. · 4.54 Impact Factor
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Journal of Antimicrobial Chemotherapy 10/2007; 60(3):704-6. · 5.07 Impact Factor
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Journal of Antimicrobial Chemotherapy 05/2007; 59(4):804-5. · 5.07 Impact Factor
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ABSTRACT: The aims of the present study were to investigate at the farm-owner level the effect of prescribed tetracycline consumption in pigs and different Salmonella Typhimurium phage types on the probability that the S. Typhimurium was resistant to tetracycline. In this study, 1,307 isolates were included, originating from 877 farm owners, and data were analyzed using logistic regression. The analysis showed that both the S. Typhimurium phage type (p < 0.0001) and an increase in tetracycline consumption (p = 0.0007) were significantly associated with tetracycline resistance. In particular, the phage type was strongly associated with tetracycline resistance. A further analysis of data from the Danish Integrated Antimicrobial Resistance Monitoring and Research Programme (DANMAP) indicates that the tetracycline-susceptible phage types only slowly become tetracycline resistant, although tetracycline consumption more than doubled at the national level from 12,000-13,000 kg of active compound in 1996-1998 to 29,000 kg of active compound in 2004. Instead, tetracycline-resistant S. Typhimurium phage types became more prevalent. This suggests that the spread of already established or new resistant clones, rather than conversion of "old" well-established susceptible clones to resistant clones by uptake of resistance genes, explains most of the increased levels of tetracycline resistance in S. Typhimurium in Danish swine production in response to increased tetracycline consumption.
Microbial Drug Resistance 01/2007; 13(4):289-94. · 2.15 Impact Factor
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M Pringle, F M Aarestrup,
B Bergsjø,
M Fossi,
E Jouy,
A Landén,
D Mevius,
K Perry,
C Teale,
J Thomson,
T Skrzypczak,
K Veldman,
A Franklin
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ABSTRACT: There are no approved standards for antimicrobial susceptibility testing of the fastidious spirochete Brachyspira hyodysenteriae. An interlaboratory study was performed to establish MIC quality control ranges for six antimicrobial agents for the type strain of B. hyodysenteriae using broth dilution. The results showed that B. hyodysenteriae B78T ATCC 27164T is a suitable quality control strain. This is a first step toward standardization of methods regarding this anaerobe.
Microbial Drug Resistance 02/2006; 12(3):219-21. · 2.15 Impact Factor
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ABSTRACT: The clinical relevance of Campylobacter concisus in gastrointestinal disease has not been determined definitively. This study investigated the phenotypic and genotypic characteristics of 39 C. concisus isolates from Danish patients with diarrhoea, three isolates from healthy individuals and the type strain. A cytolethal distending toxin (CDT)-like effect on Vero cells was observed in 35 (90%) isolates from patients with diarrhoea, in all three isolates from healthy individuals and in the type strain. Analysis of SDS-PAGE protein profiles and PCR amplification of 23S rDNA assigned the isolates into two distinct, but discordant groups. Automated ribotyping (RiboPrinting) identified 34 distinct patterns among the 43 isolates, but cluster analysis did not separate isolates from patients with diarrhoea from isolates from healthy patients. Random amplified polymorphic DNA (RAPD) analysis with three primers identified 37 unique profiles, but requires further evaluation. The isolates obtained from healthy carriers were distinguished by cluster analysis from the isolates obtained from patients with diarrhoea. All the isolates were susceptible to 11 antimicrobial agents tested. Overall, there was considerable variability between the C. concisus isolates, but there were no clear phenotypic or genotypic differences between isolates from patients with diarrhoea and isolates from healthy carriers. Further evidence is needed to support the possible role of C. concisus as a human enteric pathogen.
Clinical Microbiology and Infection 05/2005; 11(4):288-95. · 4.54 Impact Factor
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ABSTRACT: The effect of route of administration and dose of enrofloxacin (Baytril) on the development of fluoroquinolone resistance in Salmonella and Escherichia coli in the intestinal tract of pigs was investigated. Healthy pigs at the age of 8-10 weeks were infected with a mixture of susceptible wild-type (MICciprofloxacin = 0.03 microg/ml) and a mutant Salmonella typhimurium with reduced susceptibility to fluoroquinolones (MICciprofloxacin = 0.5 microg/ml) (in the ratio 99:1) and treated with 2.5 mg/kg bwt enrofloxacin by either intramuscular (i.m.) or oral (p.o.) administration at time points either 4 or 24 h after the infection. The treatment via the intramuscular route of administration (24 h after the infection) was carried out with elevated doses of 7.5 and 15 mg/kg bwt as well. Emergence of resistance during a 3-day treatment period and persistence up to 13 days after treatment, was monitored by counting the resistant and total number of coliforms and Salmonella in faeces of the pigs. High frequencies of fluoroquinolone resistance developed rapidly among the coliform flora independent of route of administration, dose or time of initiation of the treatment. Selection for resistance among the artificially introduced Salmonella was reduced by using the intramuscular route and by escalating the dose 3 or 6 times the recommended dose of 2.5 mg/kg bwt, which also resulted in shortening of the period, in which the pigs were shedding Salmonella. The resistance among the coliform flora persisted for at least 2 weeks. The Salmonella infection was cleared in all cases during the 2 weeks independent of frequency of resistance. The study showed that resistance is very easily selected by treatment with enrofloxacin at the recommended dose 2.5 mg/kg bwt, but also that the intensity of selection can be reduced by using intramuscular dosing (instead of oral dosing) and by escalating that i.m. dose. The results obtained with Salmonella also showed that even very small changes in the active drug concentrations might completely change the intensity of selection.
Research in Veterinary Science 01/2004; 75(3):185-93. · 1.65 Impact Factor
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ABSTRACT: The aim of this study was to evaluate the Danish surveillance program of Streptococcus agalactiae in dairy herds with respect to 1) fluctuation over time of the presence of S. agalactiae in bulk tank milk, 2) sensitivity and specificity of the bacteriological method used, and 3) contamination of bulk tank milk samples with milk from other herds. From June to September 1996, bulk tank milk was sampled from 100 Danish dairy herds seven times, with intervals of 2 wk. The samples were examined for the presence of S. agalactiae by four different methods: 1) by the method approved for the program, 2) after ultrasonic treatment of the milk before examination, 3) after freezing down the milk before examination, and 4) after selective preparation of the milk. Selected strains of S. agalactiae were examined by restriction fragment length polymorphism of the gene encoding rRNA to discriminate between the isolates. Streptococcus agalactiae was found in eight of 96 herds in which S. agalactiae had never previously been found during the surveillance program. Streptococcus agalactiae was not found in all seven sampling rounds in any of the eight herds. Comparing the approved method with supplemental findings by the other methods, the estimated sensitivity was (95% confidence limits): 0.786 (0.628; 0.892) and the estimated specificity (95% confidence limits): 0.995 (0.985; 0.999). Using all four methods on the same sample could increase the sensitivity, but by comparing the methods individually, there was no significant difference between any of them (P > 0.10). In milk samples from three herds, the ribotype of S. agalactiae was the same as in milk from herds sampled just before; therefore, it could not be ruled out that cross-contamination could occur. Taking into account that S. agalactiae in bulk tank milk reflects the presence of S. agalactiae in at least one udder quarter, this investigation gives further reason to assume that S. agalactiae can be seen sporadically in several herds. A surveillance program based on annual bulk tank milk sample examinations will only detect a limited number of S. agalactiae infected herds. If the overall aim is to identify herds where the infection is established, annual bulk tank milk sample examinations combined with the information of number of colonies of S. agalactiae in the sample will be sufficient.
Journal of Dairy Science 04/2003; 86(4):1233-9. · 2.56 Impact Factor
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ABSTRACT: The concentration of enrofloxacin in plasma, intestinal tissue, lymph nodes and intestinal contents was investigated in healthy pigs after oral (p.o.) and intramuscular (i.m.) administration of a single dose of 2.5 mg/kg bw. Tissue and content samples were collected from jejunum, ileum, caecum and colon from pigs killed at 2, 3 and 6 h after dosing. Intramuscular administration resulted in significantly higher concentrations in plasma, intestinal tissue and lymph nodes at 2 h but not at 3 or 6 h compared with p.o. administration. The absorption and distribution phase was longer after oral administration, and maximum concentrations in tissue and plasma were determined later than after i.m. administration. No difference between route of administration was observed in the intestinal content. Enrofloxacin concentrations in faeces during a 5-day dosing regimen with i.m. and p.o. administration were determined by both HPLC and bio-assay. Higher concentrations were found after i.m. administration during the first day, but the difference was not significant after 2 days. The biologically active concentrations determined by bio-assay constituted 48-75% of the total concentrations determined by HPLC. On the basis of these results it was concluded that in order to ensure an immediate high concentration of enrofloxacin, and thereby avoid an initial selection for resistant mutants, the intramuscular route seems to be preferable to the oral route.
Journal of Veterinary Pharmacology and Therapeutics 11/2002; 25(5):335-42. · 1.18 Impact Factor
