Pharmacokinetics of florfenicol and thiamphenicol in ducks

The pharmacokinetics of florfenicol (FF) and thiamphenicol (TP) after single intravenous (IV) and oral (PO) administration was investigated in Mulard ducks. Both antibiotics were administered at a dose of 30 mg/kg body weight, and their concentrations in plasma samples were assayed using high‐performance liquid chromatography with ultraviolet detection. Pharmacokinetic parameters were calculated using a noncompartmental method. After IV administration, significant differences were found for the mean residence time (2.25 ± 0.21 hr vs. 2.83 ± 0.50 hr for FF and TP, respectively) and the general half‐life (1.56 ± 0.15 hr vs. 1.96 ± 0.35 hr for FF and TP, respectively) indicating slightly slower elimination of TP as compared to FF. The clearance, however, was comparable (0.30 ± 0.07 L/hr/kg for FF and 0.26 ± 0.04 L/hr/kg for TP). The mean volume of distribution was below 0.7 L/kg for both drugs. Pharmacokinetics after PO administration was very similar for FF and TP suggesting minor clinical importance of the differences found in the IV study. Both antimicrobials showed rapid absorption and bioavailability of more than 70% indicating that PO route should be an efficient method of FF and TP administration to ducks under field conditions.     

猪肉源金黄色葡萄球菌毒力基因检测与耐药性分析

【目的】了解陕西关中地区猪肉中金黄色葡萄球菌(Staphylococcus aureus)的污染状况、耐药性及其毒素基因的分布。【方法】采集陕西关中6个地区的猪肉165份,按国标GB/T 4789.10-2010的方法,对其中的金黄色葡萄球菌进行分离,采用PCR方法对该菌进行确证并对其相关基因(如nuc、mecA、PVL、SEs和ETs)进行检测,最后采用琼脂稀释法检测金黄色葡萄球菌对11种抗菌药物的耐药性。另外,在BP平板中分别添加头孢西丁(4μg/mL)和苯唑西林(4μg/mL),分离耐甲氧西林金黄色葡萄球菌(MRSA)。【结果】165份样品的金黄色葡萄球菌污染率为33.33%(55/165);从中分离出103株金黄色葡萄球菌,但未检测出MRSA,这些菌对甲氧苄啶的耐药性最强,耐药率为100%;其次对红霉素和四环素的耐药率较高,分别为57.28%和34.95%;对苯唑西林、庆大霉素、氯霉素、环丙沙星的耐药率分别为2.91%,10.68%,2.91%和3.88%;所有菌株对头孢西丁、头孢哌酮、万古霉素、阿米卡星均敏感,同时得到21种耐药谱,多重耐药率达20.39%。猪肉金黄色葡萄球菌中杀白细胞素基因(Panton-valentine leu-kocidin,PVL)的检出率为34.95%,肠毒素基因(SEs)中sej的检出率最高,为98.06%,然后依次为sea(50.49%)、see(34.95%)、sed(31.07%)、sec(13.59%)、seh(8.74%)、sei(8.74%)、seg(6.80%)和seb(1.94%);同时得到71种毒素基因型,以sea+sej(11.65%)最为流行,分布地区不尽相同,其次为PVL+sea+see+sej(9.71%),耐红霉素的金黄色葡萄球菌含的毒素基因类型比较复杂,sej基因检出率高达98.68%。在BP平板中分别添加头孢西丁和苯唑西林,均未检测出MRSA。【结论】猪肉存在金黄色葡萄球菌的污染,其污染菌株存在多重耐药性并携带较多毒素基因,提示应加强猪肉金黄色葡萄球菌的监测。在BP平板中分别添加头孢西丁(4μg/mL)和苯唑西林(4μg/mL)筛选MRSA的方法不一定可靠,其可信度有待证明。     

Effect of food on the pharmacokinetics of oral cefuroxime axetil in dogs

Cefuroxime axetil pharmacokinetic profile was investigated in 12 Beagle dogs after single intravenous and oral administration of tablets or suspension at a dose of 20 mg/kg, under both fasting and fed conditions. A three-period, three-treatment crossover study (IV, PO under fasting and fed condition) was applied. Blood samples were withdrawn at predetermined times over a 12-hr period. Cefuroxime plasma concentrations were determined by HPLC. Data were analyzed by compartmental analysis. No statistically significant differences were observed between formulations and feeding conditions on PK parameters. Independently of the feeding condition, absorption of cefuroxime axetil after tablet administration was low and erratic. The drug has been quantified in plasma in 3 out of 6 and 5 out of 6 dogs in the fasted and fed groups. For this formulation, the bioavailability (F), peak plasma concentration (C_max), and area under the concentration–time curve (AUC) of cefuroxime axetil were significantly enhanced (p < .05) by the concomitant ingestion of food (32.97 ± 13.47–14.08 ± 7.79%, 6.30 ± 2.62–2.74 ± 0.66 µg/ml, and 15.75 ± 3.98–7.82 ± 2.76 µg.hr/ml for F, C_max, and AUC in fed and fasted dogs, respectively), while for cefuroxime axetil suspension, feeding conditions affected only the rate of absorption, as reflected by the significantly shorter absorption half-life (T_½(a)) and time to peak concentration (T_max) (0.55 ± 0.27–1.15 ± 0.19 hr and 1.21 ± 0.22–1.70 ± 0.30 for T_½(a) and T_max in fed and fasted dogs, respectively). For cefuroxime axetil tablets, T > MIC (≤1 µg/ml) was <2 hr in fasted and ≈4 hr in fed animals, and for cefuroxime axetil suspension, T > MIC (≤1 µg/ml) was ≈5 hr and for T >MIC (≤4 µg/ml) was ≈2.5 hr for fasted and fed dogs, respectively. Cefuroxime axetil as a suspension formulation seems to be a better option than tablets. However, its short permanence in plasma could reduce its clinical usefulness in dogs.     

Severe soft tissue infections in dogs: 47 cases (1996–2006)

Objective– To describe the patient population, microbiological findings, treatment and outcome in dogs with severe soft tissue infections (SSTIs) and to compare survivors to nonsurvivors. Design– Retrospective study. Animals– Forty‐seven dogs with confirmed soft tissue infections originating from the SC tissues, muscle or fascia. Interventions– None. Measurements and Main Results– Physical and clinicopathologic data on presentation, microbiological and histopathological findings, antimicrobial treatment and outcome. Dogs with SSTIs were predominantly large breed dogs with a median body weight of 35.6 kg. Incidence of pre‐existing conditions (immunomodulating diseases, blunt trauma, injections, clean surgical procedures) that could have contributed to development of SSTIs was 34%. Abnormal physical examination and diagnostic parameters on presentation included increased body temperature (median temperature 39.5 °C [103.1 °F]) and low arterial blood pressure (median systolic blood pressure 103.5 mm Hg). While Streptococcus species were the most commonly isolated bacteria, the incidence of polymicrobial infections differed between antemortem (38.7%) and postmortem (57.1%) cultures. The overall survival rate was 46.8%. Survivors had a higher body weight and higher respiratory rate on presentation than nonsurvivors. Nonsurvivors had a significantly lower WBC count and higher lactate, BUN, aspartate aminotransferase, and bilirubin concentrations. Histopathologic examination of tissue specimens showed that the degree of necrosis was higher in survivors compared with nonsurvivors. Conclusions– SSTIs in dogs are serious conditions associated with high mortality, significant inflammatory changes, and cardiovascular compromise. A number of conditions, including those that compromise skin integrity and immunomodulating diseases have been identified in our patient population and could have contributed to development of SSTIs. Polymicrobial infections occurred in many cases, necessitating broad‐spectrum antimicrobial coverage.     

Blood culture isolates and antimicrobial sensitivities from 427 critically ill neonatal foals

OBJECTIVE: To assist correct decision-making about antimicrobial treatment of equine neonates with septicaemia. DESIGN: Retrospective study of microbial blood culture results obtained from foals less than 7 days of age. METHODS: Microbial blood culture results from foals less than 7 days of age admitted to an intensive care unit between July 1999 and December 2004 were reviewed. Antimicrobial sensitivity was assessed by the Kirby Bauer disc diffusion method. Antimicrobials were defined as an effective first-line choice antimicrobial if greater than 70% of isolates were susceptible. Multiple drug resistance (MDR) was defined as resistance to at least three antimicrobials in different chemical classes or with different mechanisms of resistance. RESULTS: Of the 427 Thoroughbred foals included in the study, a positive blood culture was obtained in 110 foals and 124 microorganisms were isolated. Gram-positive isolates, predominantly Streptococcus/Enterococcus spp, were obtained in 41% of foals. Gram-negative isolates were predominantly of the Enterobacteriaceae family, in particular Escherichia coli. The overall antimicrobial sensitivity of the isolates was low. The Gram-positive organisms had unpredictable sensitivity patterns. MDR was recorded in 32% of isolates. In total, 81% of foals were discharged from hospital and 74.5% of foals with a positive blood culture were discharged. CONCLUSION: With the increasing prevalence of Gram-positive microorganisms and their unpredictable sensitivity patterns, blood cultures remain important in the diagnosis and treatment of equine neonatal septicaemia.     

Diagnoses and treatments in health-classified fattening herds rearing pigs all in-all out

This study describes diseases encountered, medications used and veterinary involvement in all in--all out finishing herds belonging to one pork production system. The finishing herds had a particular management and housing regime. The pigs originated from health classified farrowing units. Information on 207,442 pigs was collected from 595 log books. Altogether 91% of the pigs received no treatments. Four percent of the batches of pigs were given antimicrobial mass medications. The local veterinarian visited the herds on average 2.6 times during the finishing period and made the diagnoses in more than half of the cases. At least one pig was affected with arthritis or tail biting in more than half of the batches, whereas locomotory diseases were recorded in one third of the batches. All other diagnoses were encountered in 1%-13% of the batches. Only a few pigs were treated individually in the affected groups. Antimicrobial drugs were given to 8% and other medicines to 0.7% of the pigs. The diagnosis was missing at least for one pig in 29% of the batches and the information about the medicine use in 8% of the treatments was missing. The study shows that it is possible to rear finishing pigs with only a small proportion of the animals needing treatments. The need of mass medications was low, because infectious diseases affecting the whole herd were uncommon. The recommendations for antimicrobial use given by the authorities had been followed quite well. The farmers and the veterinarians should be educated in order to realise the importance of proper record keeping.