• 대한수의학회지
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• 제44권3호
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• pp.367-371
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• 2004

This report describes the determination of ceftiofur residues in milk from treatment of lactating dairy cattle by intramuscular injection of three consecutive daily doses of about 1 mg /kg BW, the recommended label dosing. The separation of ceftiofur was achieved on $C_1_8$ reverse phase column. The mobile phase consisted of 0.1% trifluoracetic acid in water (A) and 0.05% acetic acid in acetonitrile (B) and grediently flowed at the flow rate of 0.4 mL/min. As a result of analysis of blank raw bovine milk samples, matrix interference was not shown. Limit of detection and limit of quantitaion was 0.5 ng/mL and 1 ng/mL, respectively. The values of precision and recovery satisfied the guideline of National Veterinary Research and Quarantine Service (NVRQS, Korea). The mean residual concentration of ceftiofur in milk did not exceed 3.71 ng/mL when ceftiofur was administered intramuscularly to lactating dairy cattle for 3 consecutive days at 1 mg/kg of BW per day. It is much lower than the proposed MRL (100 ng/mL) of ceftiofur in milk.

• 대한수의학회지
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• 제43권3호
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• pp.429-433
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• 2003

This study was aimed to develop a more rapid, simple and sensitive method to determine ceftiofur in bovine serum using LC/MS with electrospray interface. Separation was achieved on the Nova-Pak $C_{18}$ reverse phase column. The mobile phase consisted of 0.1% acetic add in water (A) and acetonitrile (B) and gradiently flowed at the rate of 0.4 mL/min. As a result of analysis of blank muscle samples, matrix interference was not shown. Limit of detection and limit of quantitaion was 5 ng/g and 20 ng/g, respectively. The values of precision and recovery satisfied the guideline of NVRQS. The precision and recovery developed in this method are suitable and sensitive to determine the concentration of ceftiofur in the bovine serum. These results could be applied for the confirmation and quantification in the biofluid.

• Mass Spectrometry Letters
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• 제2권1호
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• pp.16-19
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• 2011

Oxidation products of ceftiofur were formed in hydrogen peroxide solution. The structures of the ceftiofur oxidation products were characterized by high-performance liquid chromatography/electrospray ionization/tandem mass spectrometry (HPLC/ESI/MS/MS). The products were identified as compounds oxidized at the sulfur of a cephem ring. For further analysis, experiments were performed using $O^{18}$-labeled hydrogen peroxide. In addition, density-functional calculations were carried out for six possible oxidation products to support the experimental results.

• Journal of Veterinary Science
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• 제22권6호
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• pp.78.1-78.10
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• 2021

Background: Recurrent subclinical mastitis (RScM) due to resistant bacteria has low clinical and bacteriological cure rates, often requiring the culling of cows. The sequential intramammary administration of enrofloxacin hydrochloride-dihydrate (enro-C) followed by ceftiofur HCl may be useful for treating these cases. Objectives: This study assessed the bacteriological and clinical cure-efficacies of the sequentially intramammary administration of enro-C, followed by ceftiofur HCl to treat RScM in Holstein/Friesian cows. Methods: This trial was conducted in a herd with a high prevalence of RScM, and 20 Holstein/Friesian cows were included: 45% suffering subclinical mastitis and 38.9% of the mammary quarters affected. Twenty-nine bacterial isolates in vitro resistant to enro-C were obtained (coagulase-negative Staphylococcus spp, 55.2%; Staphylococcus aureus, 27.6%; Escherichia coli, 6.9%; Streptococcus uberis, 6.9%; Corynebacterium bovis, 3.4%). Polymerase chain reaction-isolated the following genes linked to enro-C resistance: chromosomal (gyrA) and plasmid (aac(6')-lb-cr). The treatments were as follows: twice-daily intramammary infusions of enro-C (300 mg/10 mL) for 5 days. Cows clinically considered treatment failures were also treated with intramammary ceftiofur (125 mg/10 mL, twice daily for 5 days. The clinical and bacteriological cure rates were carried out when completing each treatment phase and at 14 and 21 days, aided by a California mastitis test, somatic cell count, and failure to identify the initially causative bacteria. Results: Enro-C achieved 65% clinical and bacteriological cure rates, and 100% cure rates were obtained after the rescue treatment with ceftiofur HCl. Conclusions: Outstanding clinical and bacteriological cure rates in cows affected by RScM were achieved with the consecutive intramammary infusions of enro-C, followed by ceftiofur HCl.

• Mass Spectrometry Letters
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• 제10권2호
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• pp.43-49
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• 2019

The aim of this study was conducted to develop an analytical method to determine the concentration of ceftiofur residue in eel, flatfish, and shrimp. For derivatization and extraction, the sample was hydrolyzed with dithioerythritol to produce desfuroylceftiofur, which was then derivatized by iodoacetamide to obtain desfuroylceftiofur acetamide. For purification, the process of solid phase extraction (Oasis HLB) was used. The target analytes were confirmed and quantified in $C_{18}$ column using liquid chromatography-tandem mass spectrometry with 0.1% formic acid in water (A) and 0.1% formic acid in acetonitrile (B) as the mobile phase. The linearity of the standard calibration curve was confirmed by a correlation coefficient, $r^2>0.99$. The limit of quantification for ceftiofur was 0.002 mg/kg; the accuracy (expressed as the average recoveries) was 80.6-105%; the precision (expressed as the coefficient of variation) was below 6.3% at 0.015, 0.03, and 0.06 mg/kg. The validated method demonstrated high accuracy and acceptable sensitivity to meet the Codex guideline requirements. The developed method was tested using market samples. As a results, ceftiofur was detected in one sample. Therefore, it can be applied to the analysis of ceftiofur residues in fishery products.

• 생명과학회지
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• 제23권9호
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• pp.1133-1139
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• 2013

돼지 원정액의 채취나 희석정액의 제조과정 중 세균오염이 많이 발생하는데, 이는 정자활력의 감소뿐 아니라 모돈의 수태율 저하 등을 유발한다. 특히 Serratia marcescens는 환경에 널리 존재하며 비위생적으로 제조된 정액에 많이 분리되고 있다. 본 연구에서는 S. marcescens의 신속한 동정을 위하여 PCR 기법을 개발하였으며, 국내 돼지정액 유래 S. marcescens을 이용하여 최소생육억제농도(MIC) 등을 조사하고 유효 항생제를 선발하고자 하였다. 개발 PCR 기법은 S. marcescens에서만 306 bp의 특이 유전자 증폭산물을 형성하였으며, 기타 돼지정액에서 분리 보고된 균주나 Serratia 속균에서는 유전자 증폭 산물이 형성되지 않아 특이성이 인정되었다. PCR 기법의 민감도는 S. marcescens에서 추출된 DNA $50pg/{\mu}l$까지 검출이 가능하였다. 디스크확산법에 의한 국내 돼지정액 유래 S. marcescens의 항생제 감수성을 조사한 결과, gentamicin, ceftiofur, neomycin 등에서 80% 이상의 높은 감수성을 보였다. 한편 ceftiofur, enrofloxacin, gentamicin, neomycin의 $MIC_{90}$는 각각 8, 8, 8, $16{\mu}g/ml$로 나타났다. 따라서 개발된 PCR 기법은 S. marcescens를 동정하는 유용한 방법이며, gentamicin 등 선발된 항생제는 S. marcescens에 의한 정액 내 세균오염을 관리하기 위한 희석제용 항생제로 추천된다.

• 대한수의학회지
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• 제52권2호
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• pp.133-139
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• 2012

Antimicrobial resistance is one of the most concerns in pig industry. Escherichia (E.) coli have been used for the indicator to monitor the antimicrobial resistance. In this study, 321 E. coli from diarrheic and non-diarrheic piglets were tested for antimicrobial resistance and frequency of $Bla_{TEM}$. In non-diarrheic piglets, they were resistant to oxytetracycline (93%), streptomycin (92%) and sulfadiazine (90%) but susceptible to ceftiofur (99%), colistin (97%), and enrofloxacin (82%). The isolates from diarrheic piglets were resistant to enrofloxacin (72.9%), ceftiofur (17.6%), and colistin (11.3%), whereas the resistance was 1%, 18% and 3% in case of non-diarrheic piglets, respectively. The resistance for amoxicillin/clavulanic acid (54.1%) and ceftiofur (22%) was high in isolates from post-weaning piglets. The resistance for colistin was 15.2% in nursery piglets. Seventy-three percent of isolates from diarrheic piglets showed high multidrug resistance profile (more than 13 antimicrobials) compared to those from non-diarrheic pigs in which 71% of isolates showed moderate multidrug resistance profile (7 to 12 antimicrobials). The frequency of $Bla_{TEM}$ in E. coli from non-diarrheic and diarrheic piglets was 57% and 69%, respectively. The results might provide the basic knowledge to establish the strategies for treatment and reduce antibiotic resistance of E. coli in piglets.

• Journal of Veterinary Science
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• 제21권6호
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• pp.87.1-87.11
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• 2020

Background: A new, extended long-acting tilmicosin (TLAe) preparation was tested against intramammary ceftiofur (CEF) using a non-inferiority trial model during dry-cow therapy (DCT) in a farm with high bovine population density and deficient hygiene application. Objectives: To evaluate the possibility that TLAe administered parenterally can achieve non-inferiority status compared to CEF administered intramammary for DCT. Methods: Cows were randomly assigned to TLAe (20 mg/kg subcutaneous; n = 53) or CEF (CEF-HCl, 125 mg/quarter; n = 38 cows) treatment groups. California mastitis testing, colony-forming unit assessment (CFU/mL), and number of cases positive for Staphylococcus aureus were quantified before DCT and 7 d after calving. A complete cure was defined as no bacteria isolated; partial cure when CFU/mL ranged from 150 to 700, and cure-failure when CFU/mL was above 700. Results: TLAe and CEF had overall cure rates of 57% and 53% (p > 0.05) and S. aureus cure rates of 77.7% and 25%, respectively (p < 0.05). The pathogens detected at DCT and 7 days after calving were S. aureus (62.71% and 35.55%), Staphylococcus spp. (22.03% and 35.55%), Streptococcus uberis (10.16% and 13.33%), and Escherichia coli (5.08% and 15.55%). Non-inferiority and binary logistic regression analyses revealed a lack of difference in overall efficacies of TLAe and CEF. Apart from S. aureus, S. uberis was the predominant pathogen found in both groups. Conclusions: This study is the first successful report of parenteral DCT showing comparable efficacy as CEF, the gold-standard. The extended long-term pharmacokinetic activity of TLAe explains these results.

• 한국동물위생학회지
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• 제38권4호
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• pp.259-264
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• 2015

We investigated the residues of 6 cephalosporins (cefquinome, cephalexin, cephalonium, cefazolin, ceftiofur, cefuroxime) using LC-MS/MS in raw meat in Seoul. This method involves extraction of the residue from the meat by distilled water and methanol followed by a manual of residue analysis published by the National Institute of Food and Drug Safety Evaluation. The recoveries ranged between 74.71~90.01% in beef, 73.37~101.40% in pork and 70.87~95.53% in chicken, respectively. The limits of detection were 0.0004~0.0563 mg/kg, and the limits of quantification were 0.001~0.169 mg/kg respectively. Residues of cephalosporins which exceeded maximum residue limits (MRL) were not exceed in any of the 287 samples. However, it is necessary to develop multi-method, which includes the active metabolites of ceftiofur.

• Journal of Veterinary Science
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• 제22권6호
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• pp.41.1-41.14
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• 2021

Background: Our previously prepared ceftiofur (CEF) hydrochloride oily suspension shows potential wide applications for controlling swine Streptococcus suis infections, while the irrational dose has not been formulated. Objectives: The rational dose regimens of CEF oily suspension against S. suis were systematically studied using a pharmacokinetic-pharmacodynamic model method. Methods: The healthy and infected pigs were intramuscularly administered CEF hydrochloride oily suspension at a single dose of 5 mg/kg, and then the plasma and pulmonary epithelial lining fluid (PELF) were collected at different times. The minimum inhibitory concentration (MIC), minimal bactericidal concentration, mutant prevention concentration (MPC), post-antibiotic effect (PAE), and time-killing curves were determined. Subsequently, the area under the curve by the MIC (AUC_0-24h/MIC) values of desfuroylceftiofur (DFC) in the PELF was obtained by integrating in vivo pharmacokinetic data of the infected pigs and ex vivo pharmacodynamic data using the sigmoid E_max (Hill) equation. The dose was calculated based on the AUC_0-24h/MIC values for bacteriostatic action, bactericidal action, and bacterial elimination. Results: The peak concentration, the area under the concentration-time curve, and the time to peak for PELF's DFC were 24.76 ± 0.92 ㎍/mL, 811.99 ± 54.70 ㎍·h/mL, and 8.00 h in healthy pigs, and 33.04 ± 0.99 ㎍/mL, 735.85 ± 26.20 ㎍·h/mL, and 8.00 h in infected pigs, respectively. The MIC of PELF's DFC against S. suis strain was 0.25 ㎍/mL. There was strong concentration-dependent activity as determined by MPC, PAE, and the time-killing curves. The AUC_0-24h/MIC values of PELF's DFC for bacteriostatic activity, bactericidal activity, and virtual eradication of bacteria were 6.54 h, 9.69 h, and 11.49 h, respectively. Thus, a dosage regimen of 1.94 mg/kg every 72 h could be sufficient to reach bactericidal activity. Conclusions: A rational dosage regimen was recommended, and it could assist in increasing the treatment effectiveness of CEF hydrochloride oily suspension against S. Suis infections.