Concentrations Of Cefuroxime Research Articles

Internal mammary artery harvesting and antibiotic concentrations in sternal bone during coronary artery bypass

The concentrations of two antibiotics (vancomycin and cefuroxime) in sternal bone during coronary artery bypass surgery were analyzed to examine whether antibiotic penetration is impaired after dissection and harvesting of the left internal mammary artery for grafting. Bone samples (250 mg of cancellous sternal bone from both halves of the dissected manubrium) were obtained at the time of sternal opening and closure. Twenty patients undergoing primary coronary artery bypass grafting with the left internal mammary artery were randomized so that ten received 1.5 g of vancomycin over 180 minutes and ten 3 g of cefuroxime over 30 minutes beginning at the time of induction of anesthesia. Serum samples were collected at the same time as the bone samples and 12 h after the start of the infusions. There was a slight difference in vancomycin concentration between two sternal halves after IMA dissection at the time of sternal closure (median difference, 0.2 µg/g, and 95% confidence interval, -0.55 to 0.1). This difference was not statistically significant at the P = 0.05 level (P = 0.15, Wilcoxon matched-pair test). The cefuroxime concentration of the bone was below the detection limit (7.6 to 9.2 µg/g) in all ten patients at the time of sternal closure. Harvesting the internal mammary artery for coronary artery bypass grafting may influence the concentration of vancomycin in the manubrium of the sternum.

In vitro compatibility study of cephalosporin with intraocular irrigating solutions and intracameral medications

To study the compatibility of cephalosporins with intraocular irrigating solutions and intracameral medications commonly used in cataract surgery. The was an in vitro experiment conducted in the Research Laboratory of the Department of Microbiology, the Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong. Three cephalosporins--cefazolin, cefuroxime and ceftazidime--were separately diluted and mixed with irrigating solutions and intracameral medications to form 192 samples and 12 control solutions. The cephalosporins were dissolved in normal saline and further diluted to the concentration of 1 mg in 0.1 mL with normal saline, Ringer's solution, balanced salt solution and fortified balanced salt solutions. These were mixed with balanced salt solutions or fortified balanced salt solutions, with adrenaline, acetylcholine or carbachol and kept at 37°C for 2 h. The concentrations of free cephalosporins were measured with rapid high-performance liquid chromatography at baseline (0 h) and at 2 h. Free concentrations of cephalosporins at 2 h were compared with mean baseline (0 h) value. A difference of 3 standard deviations or more was considered statistically significant. At 2 h there was a significant drop in the cefuroxime concentration in preparations in which cefuroxime was diluted with normal saline (P < 0.01). In all preparations, the final concentrations of cephalosporins were higher than the minimal inhibitory concentrations (MIC(90)) for microbials commonly isolated from the external eye. Cefazolin, cefuroxime and ceftazidime were compatible with irrigating solutions and intracameral medications commonly used in cataract surgery.

Cefuroxime Pharmacokinetics in Pediatric Cardiovascular Surgery Patients Undergoing Cardiopulmonary Bypass

The objective of this study was to determine the pharmacokinetics of cefuroxime in children undergoing cardiopulmonary bypass (CPB) for cardiovascular surgery. A prospective study. A tertiary pediatric teaching hospital. Infants and children undergoing CPB were enrolled in the study. An initial dose (mean, 24.2 ± 1.6 mg/kg) of cefuroxime was administered before surgical incision, and a second dose (mean, 14.4 ± 7.9 mg/kg) was administered in the CPB prime solution. Serial blood samples were obtained before, during, and after the CPB process. Samples were shipped on dry ice to the analytic laboratory and concentrations determined by a validated high-performance liquid chromatography method. A 2-compartment pharmacokinetic model was fitted to the data using maximum a priori-Bayesian estimation, with weight as a covariate. Monte Carlo simulations of a single-dose (25 mg/kg pre-CPB) approach and a 2-dose (25 mg/kg pre- and 12.5-mg/kg prime solution dose) approach were performed. Fifteen subjects (9 males/6 females) were enrolled in the study, with median (range) age and weight of 11 (3-34) months and 9.5 (4.5-15.4) kg, respectively. The median (range) duration of CPB was 136 (71-243) minutes. Median and range cefuroxime pharmacokinetic parameters were as follows: maximum concentration (Cmax) dose, 1: 328 (150-512) μg/mL; systemic clearance, 0.050 (0.041-0.058) L/h/kg; steady-state volume of distribution, 0.213 (0.081-0.423) L/kg; volume of distribution in the central compartment, 0.081 (0.046-0.162) L/kg; and elimination half-life, 3.76 (1.03-6.81) hours. The median 8-hour post-dose-simulated cefuroxime concentrations were 26.5 and 16.0 mg/L for the 2-dose and single-dose regimens, respectively. Manufacturers recommend that pediatric doses of cefuroxime (25-50 mg/kg) can be used in infants and children undergoing CPB to maintain adequate serum concentrations for surgical-site infection prophylaxis. A second intraoperative dose, administered through the CPB circuit, provides no additional prophylactic advantage.

An adaptable HPLC method for the analysis of frequently used antibiotics in ocular samples

Four different antibiotics, delivered individually to rabbit eyes via hydrophilic intraocular lenses soaked in the drug solution prior to implantation, were measured in aqueous and vitreous humor samples from the eyes. To meet this analytical need, we developed a sensitive, high performance liquid chromatographic (HPLC) method for measuring the concentrations of moxifloxacin, gatifloxacin, linezolid, and cefuroxime in the ocular tissue. Separations were carried out on a LichroSpher RP-18 column, maintained at room temperature. The fluoroquinolones were eluted with a mobile phase consisting of 20% acetonitrile, in 0.1% trifluoroacetic acid (pH 3.0) with 30 mM tetrabutylammonium chloride. Linezolid and cefuroxime were eluted with 25% acetonitrile in 25 mM Na acetate buffer, pH 5.0. All elutions were isocratic. With ultraviolet detection, the lower limit of quantitation (LLOQ) for these compounds approached 1 ng (on-column injection). By using fluorescence detection, the LLOQ for the fluoroquinolones improved to 200 pg. The overall accuracy of the method was ≥90%. With minor modifications, the method was optimized for each of the agents, and the resulting analytical sensitivity made the method suitable for clinical investigations of the ocular penetration of these drugs.

Assessment of sodium hyaluronate gel as vehicle for intracameral delivery of cefuroxime in endophthalmitis prophylaxis

Sodium cefuroxime is a second-generation cephalosporin widely used at 10mg/mL for endophthalmitis prophylaxis after cataract surgery. Sodium cefuroxime solution is usually conditioned in pre-filled syringes then frozen for storage. In the present study, 0.2% sodium hyaluronate gel, natural extracellular polymer used in wound healing, was compared to conventional saline solution (0.9% sodium chloride) as drug delivery systems for cefuroxime loading in pre-filled syringes. Therefore, the temperature (4 and 25 degrees C) and time of storage (up to 21 days) varied in order to appreciate both cefuroxime and vehicle stability. Furthermore, the kinetics of drug release from both hyaluronate gel and saline solution were compared since in vitro sets of dialysis experiments. Results indicated that cefuroxime loaded in either saline solution or hyaluronate hydrogel was found stable in pre-filled syringes stored at 4 degrees C for 21 days, whereas cefuroxime degradations products appeared from the 2nd day of storage at 25 degrees C. Both drug delivery systems were found bioequivalent, although statistically slower cefuroxime dialysis was evidenced by using sodium hyaluronate vehicle. Noteworthy, cefuroxime concentration in drug delivery systems during dialysis experiment remained greater than the minimum inhibitory concentrations reported for resistant strains. In conclusion, the present stability and release study confirmed that sodium hyaluronate hydrogel is a promising vehicle for cefuroxime intracameral delivery in endophthalmitis prophylaxis.

Pharmacokinetics of Cefuroxime in Traumatic Wound Secretion and Antibacterial Activity Under Vacuum Therapy

The objective of this study was to investigate the pharmacokinetics of cefuroxime in wound secretion and the antibacterial activity of the traumatic wound secretion inpatients receiving cefuroxime and in those not receiving antibiotics. Included in the present controlled, prospective, non-randomized study were 12 patients with an open fracture who needed vacuum therapy (group A) and 12 patients with a closed fracture, who, due to soft tissue damage, also underwent treatment with vacuum therapy (group b). Wound secretion was obtained on the first, third and fifth postoperative days and exposed to the test bacteria, Staphylococcus aureus and Staphylococcus epidermidis. Patients in group A underwent systemic antibiotic treatment with cefuroxime administered intravenously at a dose of 1.5 g every 8 hours. Patients in group b did not receive antibiotics. Cefuroxime concentrations were determined using high-performance liquid chromatography (HPLC). Antibacterial activity was deter-mined using the inhibition test.Maximum cefuroxime concentrations in wound secretion were measured at 4-5 hours following intravenous administration and, with a mean concentration of 10 mg/L, remained consistently above the minimum inhibitory concentration (MIC) for the test bacteria at all points during the measurement period. As expected, the antibacterial activity of the wound secretion in patients in group A (cefuroxime) was higher than that in group b (no antibiotics). In group A, antibacterial activity against S. aureus was 94.6% and 100% against S. epidermidis. In group B, antibacterial activity against S. aureus was 61% and 81% against S. epidermidis. Cefuroxime reaches the highest level in wound secretion after 4 hours. The high antibacterial activity of the wound secretion in traumatic closed fractures is elevated by cefuroxime. In addition, our findings show that vacuum therapy of wounds is suitable as anon-invasive method for studying the pharmacokinetics of antibiotics.

Soft tissue penetration of cefuroxime determined by clinical microdialysis in morbidly obese patients undergoing abdominal surgery

Antibiotic prophylaxis is intended to prevent postoperative wound infections, a major source of morbidity and mortality in surgical patients. Cefuroxime is a well-established second-generation cephalosporin that is given preoperatively in surgery units at a standard dose of 1.5 g. It is therefore important to determine whether cefuroxime distributes to the interstitial space fluid (ISF) of subcutaneous (s.c.) soft tissues, especially in obese patients who are at a higher risk of surgical site infections. In a single centre, prospective, open-label study, six morbidly obese patients [body mass index (BMI) ≥ 40] undergoing abdominal surgery received a single intravenous dose of 1.5 g cefuroxime within 1 h of incision. Blood and microdialysis samples from the ISF of skeletal muscle and s.c. adipose tissue were collected before, throughout and after surgery for up to 6 h post-dosing. Cefuroxime concentrations were determined by high-performance liquid chromatography–ultraviolet (HPLC-UV). Total peak concentrations in plasma ( C max) (66.8 ± 18.9 μg/mL) were higher than free C max levels in the ISF of muscle (60.1 ± 15.2 μg/mL) and s.c. adipose tissue (39.2 ± 26.4 μg/mL). Mean area under the free concentration–time curve ratios of muscle/total plasma (1.0 ± 0.2) or s.c. adipose tissue/total plasma (0.6 ± 0.5) indicate that cefuroxime distributes into the ISF of these tissues. In conclusion, the findings of this pilot study indicate that cefuroxime distributes into the ISF of muscle and s.c. adipose tissue of morbidly obese patients undergoing abdominal surgery. Concentrations in the ISF of soft tissues following a single 1.5 g dose may be high enough to prevent infections with Gram-positive organisms but may be insufficient to prevent infections with Gram-negative organisms.

The Effect of a Modified Posterior Approach on Blood flow to the Femoral Head during Hip Resurfacing

The deep branch of the medial femoral circumflex artery is vulnerable to injury during posterior approaches to the hip. We modified the posterior approach during hip resurfacing in 10 patients by dividing the short external rotators 2 cm from their insertion into the femur. The cefuroxime concentrations in bone samples from the femoral heads were compared with results for the extended posterolateral approach from previous published work. There was no difference between the concentration of cefuroxime in bone when using the modified posterior approach (mean 5.6 mg/kg; CI 3.6 - 7.8) compared to the extended posterolateral approach (mean 5.6 mg/kg; CI 3.5 - 7.8; p=0.95). The similarity in femoral head perfusion between approaches suggests that the blood supply may be impaired further by capsulotomy and capsulectomy rather than by damage to the deep branch of the MFCA alone.

Comparison of in vitro safety profiles of vancomycin and cefuroxime on human corneal endothelial cells for intracameral use

To evaluate and compare the cytotoxic and apoptotic properties of cefuroxime and vancomycin on cultured human corneal endothelial cells (HCECs) to determine their safety for intracameral use. Human corneal endothelial cells were harvested from human donor eyes and exposed to various concentrations of cefuroxime and vancomycin (0.15 to 15 mg/mL). For cytotoxicity testing, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test was performed. Annexin V binding combined with propidium iodide (PI) co-staining was used for the distinction of viable, early, and late apoptotic cells. Odds ratios (ORs) and confidence intervals were calculated for the control group (without drug exposure) for 2.75 mg/mL and 15 mg/mL. Cell morphology and immunolocalization of zonula occludens 1 (ZO1) were assessed after 24 hours of drug exposure. Reduction in cell viability was observed in a dose-dependent manner after exposure to both drugs. Cefuroxime concentrations higher than 2.75 mg/mL and vancomycin concentrations higher than 5.0 mg/mL led to significant reduction in cell viability. The mean number of annexin V-positive and PI-positive cells was not significantly increased at 2.75 mg/mL for either antibiotic agent. After exposure to 15.0 mg/mL, however, the late apoptotic/necrotic cells predominated, with higher ORs indicating accelerated cell death. Increasing concentrations of both antibiotic agents resulted in fading immunopositivity for ZO1. These data suggest a dose-dependent toxicity of cefuroxime and vancomycin on HCECs in vitro with a narrow range of safety. Although the clinically used concentrations seem to be safe, slightly higher concentrations might induce irreversible cell death and thus should be avoided.

Intracameral cefuroxime: evaluation of stability in normal saline and balanced salt solutions

Abstract Purpose Intracameral cefuroxime use is an increasing practice to prevent post‐operative bacterial endophthalmitis following cataract surgery. First objective is to test stability of cefuroxime solution up to seven days at +4 °C in normal saline solution (NSS). Second objective is to evaluate if cefuroxime may be stable when prepared and stored in a less described solvent: balanced salt solution (BSS). Methods 0.4 mL syringes containing cefuroxime solution at 10 mg per mL are prepared in a laminar air flow by pharmacists. One set of 18 syringes is prepared with NSS, another set is prepared with BSS and stored in the same conditions (+ 4°C). Three syringes of each solvent are randomly selected every day after preparation (day 1) and tested for their cefuroxime content on day 1, 2, 3, 4, 5, 7. Cefuroxime content is measured by high performance liquid chromatography coupled with UV detection without any modification prior to injection. Results In NSS a concentration of 9.1 mg/mL [8.8 – 9.4] is measured on day 7, that is statistically different from the concentration of 9.9 mg/mL [9.4 – 10.4] measured on day 1. In BSS a concentration of 10.4 mg/mL [10.2 – 10.7] is measured on day 7, that is statistically not different from the concentration of 10.6 mg/mL [10.4 – 10.8] measured on day 1. Conclusion The decrease of cefuroxime concentration observed in NSS is not a subject of major concern due to its limited intensity (&lt; 10%). Moreover, syringes are currently used before day 7 in practice. The good physico‐chemical stability observed in BSS is promising but should be confirmed by microbiological tests.

Cefuroxime-impregnated calcium phosphates as an implantable delivery system in experimental osteomyelitis

The study aimed to investigate the effectiveness of porous calcium phosphates viz., hydroxyapatite (HAp) and a bi-phasic calcium phosphate (BCP) with predominately β-tricalcium phosphate (β-TCP) prepared by aqueous solution combustion method impregnated with cefuroxime axetil for the treatment of experimental osteomyelitis and compared with parenteral treatment. In vitro release of the drug was tested for its sustained elution characteristics for 21 days in PBS (pH 7.2) and measured by HPLC. In the in vivo study, bone infection was induced in tibia of rabbits by inoculation of 1 ml (3 × 10 6) CFU Staphylococcus aureus. On the 21st day, after the development of osteomyelitis, six animals were treated by filling the cavity with cefuroxime-impregnated HAp blocks (Group II), six animals with the same drug-impregnated β-TCP (Group III) and in six others, only cefuroxime (15 mg/kg twice daily) was injected parenterally 6 weeks (Group IV). Group I with six animals was kept untreated. Histologically, the signs of infection were found to subside by 3 and 6 weeks. Radiological evaluation with cefuroxime-impregnated HAp and β-TCP pointed out the disappearance of sequestrum and existence of newly formed bony specules. Concentration of cefuroxime in bone and serum as estimated by HPLC showed highest value on day 21 itself which reduced marginally by day 42 in both the groups and these values were higher than minimum inhibitory concentration (MIC) against S. aureus. Our findings suggest that bi-phasic calcium phosphates with predominately β-TCP content is a very efficient carrier material for antibiotic compounds even for refractory infections by S. aureus.

TISSUE AND PLASMA CONCENTRATIONS OF ANTIBIOTIC DURING CARDIAC SURGERY WITH CARDIOPULMONARY BYPASS - MICRODIALYSIS STUDY

Surgical-site infections are very serious complications of cardiac operations. Use of cardiopulmonary bypass (CPB) is associated with profound physiological changes, which affects the pharmacokinetic behaviour of prophylactic antibiotics. The aim of this study was to monitor tissue concentrations of cefuroxime in peripheral tissue (skeletal muscle) during cardiac surgery using CPB by means of a microdialysis. Eleven adult patients operated on using CPB were included in the study. Cefuroxime was the prophylactic antibiotic and study drug given. Microdialysis was performed by probe CMA 60 inserted into the patient's left deltoid muscle. Samples of dialysates were collected at intervals: before CPB, each 30 minutes of CPB and at the end of CPB. Samples of blood were collected at intervals: incision, start of CPB, each 30 minutes of CPB, at the end of CPB and at the end of surgery. The mean (+/- S.D.) concentrations of cefuroxime in peripheral tissue were 105.4+/-41.1, 81.7+/-32.8, 74.6+/-26.0, 70.4+/-34.7, 60.5+/-27.2, 138.0+/-42.6 (mg l(-1)). Total plasma concentrations of cefuroxime were 154.4+/-41.6, 73.3+/-20.7, 67.1+/-20.4, 59.2+/-21.0, 49.0+/-16.4, 110.9+/-33.6 (mg l(-1)) and concentrations of free plasma fraction were 110.7+/-37.1, 62.2+/-18.8, 58.9+/-18.6, 48.4+/-16.6, 41.7+/-15.6, 97.6+/-28.6 (mg l(-1)). The plasma and tissue concentrations exceed throughout the operation time the minimum inhibitory concentration for most common suspected pathogens in cardiac surgery. Results show that CPB can modify the time course of cefuroxime tissue and plasma concentrations. Microdialysis is suitable for antibiotic tissue measurement in cardiac surgery.

Serum, knee synovial fluid and joint tissue cefuroxime concentration in perioperative use before orthopedic interventions after tourniquet or in the bloodless field

A requirement to be met when administering perioperative prophylactic antibiotics as a standard with many orthopedic surgeons in artificial joint replacement is the achievement of sufficient concentrations of substance in the operative field. Following the i.v. short-infusion of 1.5 mg Cefuroxime-Sodium in 65 cases of knee joint surgery using a mid-thigh tourniquet substance levels were measured in samples of blood serum, synovial fluid and knee joint capsule. The Cefuroxime concentration in synovial fluids was found to be an average of 25.3 +/- 15.4 mcg/ml at the beginning and 14.9 +/- 10.7 mcg/ml at the end of the operations. Samples of joint capsule that had been taken during the operation showed substance levels of 20.6 +/- 11.1 mcg/ml. 13% of these samples showed substance levels below 4.0 mcg/ml which is the estimated breakpoint of full sensitivity of potentially infective bacteria. The relation of Cefuroxime concentrations in the synovial fluid to the length of time between the end of the infusion and the application of the tourniquet proved to be statistically nonsignificant (covariance analysis; p = 0.05). Nevertheless the determined differences showed a tendency which agrees with the findings of other authors who conclude, that a minimum exposure time of ten minutes is essential.

Effect of Severity Disease on the Pharmacokinetics of Cefuroxime in Children with Multiple Organ System Failure

The aim of the present study was to investigate if the severity of illness affected the pharmacokinetics of cefuroxime in 11 children diagnosed with multiple organ system failure. The patients were assigned to a severely ill group (group 1), a very severely ill group (group 2), or a control group (group 0). Blood samples were taken and cefuroxime concentrations were measured in plasma by HPLC after the first intravenous infusion of 100 mg of cefuroxime per kg of body weight. The pharmacokinetic profile of cefuroxime exhibited both one and two compartmental distribution. Statistically significant differences between the pharmacokinetic parameters of the severe (group 1) and the very severe patients (group 2) were found, and significant differences (p<0.05) in the pharmacokinetic parameters between groups 1 and 2 vs. the control group were observed for most of the parameters analyzed. However, there was no statistical difference in clearance between group 1 and the control group. The data indicate that the pharmacokinetic differences determined by severity of disease are useful for establishing an individualized regimen dosage in children with multiple organ system failure.

Serum and Uterine Concentrations of Cefazolin, Cefuroxime, and Ceftriaxone After Intraoperative Prophylactic Administration During Cesarean Section

Antibiotic prophylaxis of surgical site infections after urgent cesarean section is justified by the reduction of endometritis by two-thirds to three-quarters and a decrease in wound infections. However, not all antibiotics show adequate protection. In our study, we compared pharmacokinetic profiles of 3 commonly used antibiotics for prophylaxis: cefazolin, cefuroxime, and ceftriaxone. A total of 60 patients were enrolled in the study, divided in 3 groups, each receiving different antibiotic. Two gm cefazolin, 1.5 gm cefuroxime, or 2 gm ceftriaxone were administered in 1 intravenous dose, immediately after clamping the umbilical cord. Only concentrations of cefazolin measured in serum from the cubital vein and uterine cavum samples were above minimal inhibitory concentrations of all susceptible common pathogens for the whole intraoperative period. Cefazolin concentrations in blood from the uterine cavum were even higher than concentrations measured in blood from the cubital vein in the same time (10 minutes after intravenous injection): 89.0 mg/L versus 78.2 mg/L. The results of our study suggest a more suitable pharmacokinetic profile of cefazolin than that of cefuroxime and ceftriaxone for prophylaxis of surgical site infections after urgent cesarean section.

Spectrophotometric determination of some cephalosporin antibiotics using Prussian blue reaction

A simple, sensitive and accurate spectrophotometric method of analysis of ceftriaxone, cefotaxime and cefuroxime in pharmaceutical dosage forms has been developed and validated. The method is based on the formation of Prussian Blue (PB) complex. The reaction between the acidic hydrolysis product of the antibiotics (T = 70 � C) with the mixture of Fe 3+ and hexacyanoferate (III) ions was evaluated for the spectrophotometric determination of the antibiotics. The maximum absorbance of the coloured complex occurred at � = 700 nm and the molar absorptivity is 3.0 x 10 4 l.mol -1 cm -1 . Reaction conditions have been optimized to obtain PB complex of high sensitivity and longer stability. Under optimum conditions the absorbance of the PB complex were found to increase linearly with increase in concentrations of ceftriaxone, cefotaxime and cefuroxime, which corroborated with the correlation coefficient values. The linear range of the calibration graph was 2 - 20 �g/ml for ceftriaxone and cefotaxime and 2 - 18 �g/ml for cefuroxine. The proposed method was successfully applied to the determination of the selected antibiotics in bulk drugs and pharmaceutical formulations and the results obtained agree well with the labeled contents.

P747 Comparative minimum inhibitory concentration and mutant prevention concentration of azithromycin, cefuroxime, gemifioxacin, moxifioxacin and telithromycin against clinical isolates of Haemophilus infiuenzae

P747 Comparative minimum inhibitory concentration and mutant prevention concentration of azithromycin, cefuroxime, gemifioxacin, moxifioxacin and telithromycin against clinical isolates of Haemophilus infiuenzae

Effects of cefuroxime on human osteoblasts in vitro

The local application of antibiotics in bone cement achieves high local effective antibiotic concentrations. Cefuroxime is widely used for antibiotic prophylaxis in orthopedic surgery, and several reports highlighted a beneficial outcome if cefuroxime-impregnated bone cement was used, but there is a lack of information of direct cefuroxime effects on human bone cells. We, therefore, cultured osteoblasts, previously derived from human trabecular bone specimens and used as a cell-pool further on, with different concentrations of cefuroxime (0-1000 microg/mL) for 24, 48, or 72 h. For reversibility testing, osteoblasts were cultivated for 24 h with cefuroxime followed by 48 h without antibiotics. Cell proliferation (MTT), cytotoxicity (lactate dehydrogenase (LDH)-activity), cell metabolism (alkaline phosphatase (ALP)-activity), and extracellular matrix calcification (Alizarin staining) were assessed after antibiotic treatment. Cefuroxime concentrations of 25-100 microg/mL had little or no effect on cellular proliferation. Proliferation was significantly stimulated at 250 and 1000 microg/mL at each time. LDH-activity significantly increased at the highest concentration of 1000 microg/mL at 72 h. ALP-activity first increased at lower concentrations and then significantly decreased at 1000 microg/mL at 48 and 72 h. Similar to ALP-activity, calcification increased at lower concentrations and was not detectable at 1000 microg/mL. All revealed effects at 24 h were at least partially reversible. In the present study, we demonstrated that cefuroxime at lower concentrations had no inhibiting effects on human osteoblasts. In contrast, higher concentrations significantly altered osteoblastic function. When administered locally in total joint arthroplasty, for example, in antibiotic-impregnated bone cement, cefuroxime might critically impair osteoblastic function and periprosthetic bone metabolism.

Characterization of Klebsiella pneumoniae isolates from New Zealand sea lion ( Phocarctos hookeri) pups during and after the epidemics on Enderby Island, Auckland Islands

The 2001/2002 and 2002/2003 breeding seasons of New Zealand sea lions (NZSLs) on the Auckland Islands were marked by a high pup mortality caused by acute bacterial infections. As part of a health survey from 1998/1999 to 2004/2005, tissues and swabs of lesions had been collected at necropsy to identify the bacteria associated with pup mortality. Klebsiella pneumoniae was grown in pure culture from 83% of various organs and lesions in 2001/2002 and 76% in 2002/2003, and less frequently in the following seasons (56% in 2003/2004 and 49% in 2004/2005). Pup isolates of K. pneumoniae showed identical minimal inhibitory concentrations (MIC) of cefuroxime, neomycin, cephalotin, cephalexin and dihydrostreptomycin, suggesting clonal aetiology of the pathogen. Isolates also tested negative for production of extended-spectrum beta-lactamases (ESBLs), which was not in favour of an anthropogenetic origin of the epidemic strain. Pulsed-field gel electrophoresis (PFGE) of XbaI DNA macrorestriction fragments was performed on isolates of K. pneumoniae and Klebsiella oxytoca from 35 pups, thee NZSL adult females, and from three human patients for comparison. PFGE showed that pup isolates of K. pneumoniae were genetically indistinguishable but were neither related to K. pneumoniae from humans and from NZSL adults, nor to K. oxytoca from NZSLs. It is concluded that the 2001/2002 and 2002/2003 epidemics at Sandy Bay rookery were caused by a single K. pneumoniae clonal lineage, genetically different from the strain carried by adult NZSLs. An anthropogenic origin of the K. pneumoniae clone could not be confirmed, but further investigations are required to rule-out such occurrence.

The effect of surgical approach on blood flow to the femoral head during resurfacing

We determined the effect of the surgical approach on perfusion of the femoral head during hip resurfacing arthroplasty by measuring the concentration of cefuroxime in bone samples from the femoral head. A total of 20 operations were performed through either a transgluteal or an extended posterolateral approach. The concentration of cefuroxime in bone was significantly greater when using the transgluteal approach (mean 15.7 mg/kg; 95% confidence interval 12.3 to 19.1) compared with that using the posterolateral approach (mean 5.6 mg/kg; 95% confidence interval 3.5 to 7.8; p < 0.001). In one patient, who had the operation through a posterolateral approach, cefuroxime was undetectable. Using cefuroxime as an indirect measure of blood flow, the posterolateral approach was found to be associated with a significant reduction in the blood supply to the femoral head during resurfacing arthroplasty compared with the transgluteal approach.