Initial Specimen Diversion Device® reduces blood culture contamination and vancomycin use in academic medical centre.

BACKGROUND: In suspected bloodstream infections, accurate blood culture results are critical to timely diagnoses and appropriate antibiotic administration. AIM: An Initial Specimen Diversion Device®, Steripath® (Magnolia Medical Technologies, Seattle, WA, USA) was evaluated for efficacy in reducing blood culture contamination at Brooke Army Medical Center (6.8% six-month contamination rate prior to intervention) in a six-month quality improvement project. METHODS: Blood cultures in the emergency department were collected using either Steripath or the standard method. Blood samples of 20 mL were cultured into an aerobic and anaerobic medium and incubated for five days using an automated microbial detection system immediately after collection. Positive bottles were Gram-stained and plated. Rapid molecular polymerase chain reaction identification was performed on all first positive bottles within a blood culture set for each admission or ED visit. Speciation was deduced during antimicrobial sensitivity testing using the Vitek-2 instrument. FINDINGS: Seven out of 1016 (0.69%) contamination events occurred when using Steripath vs 53 out of 800 (6.6%) contamination events when using the standard method. Steripath use was associated with a 90% lower incidence of blood culture contamination vs the standard method. Post study, Steripath use was implemented as standard practice hospital-wide, and a retrospective data analysis attributed a 31.4% decrease in vancomycin days of therapy to Steripath adoption. CONCLUSION: Using Steripath significantly decreased blood culture contamination events for bacterial bloodstream infections compared to the standard method. Subsequent adoption of Steripath reduced overall vancomycin usage. With widescale implementation Steripath could bolster antibiotic stewardship, mitigating antibiotic resistance caused by unnecessary antibacterial treatments.

An 11,000-isolate same plate/same day comparison of the 3 most widely used platforms for analyzing multidrug-resistant clinical pathogens.

Stewardship of the dwindling number of effective antibiotics relies on accurate phenotyping. We sought to conduct the first large-scale, same plate and day comparison of the 3 most widely used bacterial analyzers. A total of 11,020 multidrug-resistant clinical isolates corresponding to more than 485,000 data points were used to compare the 3 major identification and antibiotic susceptibility testing (AST) platforms. Bacterial suspensions, prepared from a single plate, were simultaneously tested on all platforms in the same laboratory. Discrepancies were derived from MIC values using 2014 interpretive guidelines. Molecular methods and manual microbroth dilution were reference standards. Most discrepancies were due to drug-organism-AST platform combination instead of individual factors. MicroScan misidentified Acinetobacter baumannii (P<0.001) and underestimated carbapenem susceptibility in Klebsiella pneumoniae. Vitek-2 and Phoenix had higher discrepancies for blaKPC-containing Enterobacteriaceae (P<0.05) and reported false susceptibilities more often. While all platforms performed according to standards, each had strengths and weaknesses for organism identification, assaying specific drug-organism combinations and inferring carbapenemase production.

Patients with ovarian cancer have elevated (51)Cr-EDTA plasma clearance early post-operatively.

Plasma clearance of (51)Cr-EDTA (Clp(EDTA)) is widely used to determine glomerular filtration rate prior to carboplatin based chemotherapy. We have observed that many patients with ovarian cancer have elevated Clp in the early post-operative phase compared to later phases. The purpose of this study was to examine whether this observation reflects a systematic difference. We retrospectively analysed data from 53 patients who had undergone surgery for ovarian cancer. Twenty-six patients had Clp(EDTA) measured early after the operation (mean, 8 days (range, 3-16 days)) (early group), and 27 patients had Clp(EDTA) measured late post-operatively (mean, 32 days (range, 19-48 days)) (late group). Clp(EDTA) values was measured before the first, third and fifth course of chemotherapy. Additionally, age, height, weight, cancer stage, ascites and tumour histology were noted. Mean Clp(EDTA) in the early group was significantly higher than in the late group (104+/-4.4 vs 89+/-3.5 ml.min(-1) per 1.73 m(2); P =0.005). Clp(EDTA) declined significantly in the early group from the first measurement after the operation until measurement before the third course of chemotherapy but remained constant in the late group. Clp(EDTA) was not correlated to ascites, cancer stage or tumour histology. It is concluded that patients with ovarian cancer have significantly higher Clp(EDTA) in the early post-operative phase than similar patients with Clp(EDTA) measured late post-operatively.

Protein binding of 99Tcm-DTPA compared with other GFR tracers.

99Tcm-Diethylenetriaminepentaacetic acid (99Tcm-DTPA) has been postulated to be more bound to plasma proteins than are other radiopharmaceuticals used for measurement of glomerular filtration rate (GFR). The results of protein binding experiments are, however, highly related to methodology. The aim of the present study was to compare the protein binding of the 99Tcm-DTPA preparation we use in our daily routine with that of the other five 99Tcm-DTPA preparations available and with other GFR tracers by using the same ultrafiltration method. Protein binding was studied in vitro after incubation in donor plasma and in vivo after single injection in patients. A correction for the uneven distribution of ultrafiltrable ions ('Donnan effect') was included. Quality control of six 99Tcm-DTPA preparations performed with thin layer chromatography showed a high labelling efficiency (96.2-99.9%). The in vitro protein binding ranged from 9.25% to 11.12%. The in vitro protein binding of 99Tcm-DTPA was not significantly different from that of 51Cr-ethylenediaminetetraacetic acid (51Cr-EDTA) and 125I-iothalamate (10.99% vs 12.15%, and 9.55%). There was no difference in the in vivo protein binding of 99Tcm-DTPA 5 and 40 min after injection (13.28% vs 12.58%), and there was no difference in the protein binding of 99Tcm-DTPA and 51Cr-EDTA (12.93% vs 12.54%). In conclusion, in vitro and in vivo protein binding of 99Tcm-DTPA was 10-13%. The protein binding was not different from the binding of 51Cr-EDTA and 125I-iothalamate.

Plasma clearance of 99Tcm-MAG3: accuracy of five single-sample methods.

The aim of this study was to compare the accuracy of five single-injection, single-sample methods for the assessment of plasma clearance of 99Tcm-MAG3 in adults. In 51 patients, a reference plasma clearance was determined on the basis of 16 blood samples. It ranged from 13 to 313 ml.min-1. In patients with a plasma clearance less than 75 ml.min-1, there was a large difference between the clearance obtained by a single-sample method and the reference method. Thus single-sample methods should not be used with these patients. In patients with a plasma clearance higher than 75 ml.min-1, the relative difference was (mean +/- s): 6.07 +/- 9.96% (Russell et al., 1989), 14.22 +/- 8.08% (Müller-Suur et al., 1991), 7.29 +/- 6.21% (Bubeck et al., 1992), 6.64 +/- 7.71% (Russell et al., 1996) and 17.39 +/- 7.39% (Piera et al., 1997). Reference clearance was overestimated by all five single-sample methods, especially by the methods of Müller-Suur et al. and Piera et al. The smallest standard deviation was obtained using the method of Bubeck et al. This method is recommended for use in patients with a plasma clearance greater than 75 ml.min-1.

Clearance and renal extraction of technetium-99m-L,L-ethylenedicysteine, I-131-ortho-iodohippurate and I-125-iothalamate in pigs.

99mTc-L,L-ethylenedicysteine (99mTc-EC) has been proposed as a 99mTc-labelled alternative to radio-iodinated ortho-iodohippurate (OIH) for renal imaging and evaluation of renal function. The kinetics of this new renal function agent were studied by a single-injection plasma clearance technique in pigs. 99mTc-EC, 131I-OIH and 125I-iothalamate were injected and the plasma concentration of the three tracers was followed for 240 min. Renal, hepatic and total plasma clearance were calculated. There was no difference between the renal plasma clearance of 99mTc-EC and 131I-OIH (175 +/- 9 versus 178 +/- 8 ml min-1, P = 0.43), whereas the difference between the total plasma clearance of 99mTc-EC and 131I-OIH was highly significant (268 +/- 16 versus 185 +/- 9 ml min-1, P = 0.0001). 99mTc-EC had a significant hepatic clearance of 83 +/- 10 ml min-1 whereas the hepatic clearance of 131I-OIH was negligible. Renal plasma extraction of both 99mTc-EC and 131I-OIH decreased significantly between 2 and 240 min post-injection from 0.85 to 0.45% for 99mTc-EC and from 0.93 to 0.57% for 131I-OIH. Red blood cell binding of 99mTc-EC and 131I-OIH was 6.1% and 20%, respectively. The protein binding of 99mTc-EC and 131I-OIH was 32% for both tracers. We conclude that 99mTc-EC is not a suitable tracer for measuring renal function by the single-injection plasma clearance technique in pigs. This is due to a decreasing renal extraction and a significant hepatic clearance.

Renal and extrarenal clearance of 99mTc-MAG3: a comparison with 125I-OIH and 51Cr-EDTA in patients representing all levels of glomerular filtration rate.

. This investigation was undertaken in order to determine whether the clearance of technetium-99m mercaptoacetyltriglycine (99mTc-MAG3) is more closely correlated to the clearance of iodine-125 orthoiodohippurate (125I-OIH) than to the clearance of chromium-51 ethylene diamine tetra-acetate (51Cr-EDTA) and whether there is a clinically significant extrarenal clearance of 99mTc-MAG3 . Fifty-one patients with a glomerular filtration rate (GFR) of 4-132ml/min were studied. After a simultaneous single injection of the three tracers, plasma clearance was measured from blood samples 0-5h post injection (p.i.) (0-24h in patients with GFR<15ml/min). Renal plasma clearance was measured 0-5h p.i. The ratio between the renal plasma clearance of 99mTc-MAG3 and 125I-OIH was 0.57. The ratio between the renal plasma clearance of 99mTc-MAG3 and 51Cr-EDTA was 2.57. The coefficient of variation (CV) of the 99mTc-MAG3/125I-OIH ratio was significantly smaller than the CV of the 99mTc-MAG3/51Cr-EDTA ratio (13.4% versus 31.2%). The corresponding plasma clearance ratios were 0.59 (CV=14.8%) and 2.48 (CV=27.0%). Plasma clearance overestimated renal plasma clearance by 7.0ml/min (5.4%) for 99mTc-MAG3 and by 4.1ml/min (8.4%) for 51Cr-EDTA. The difference in plasma and renal plasma clearance of 125I-OIH of 5.5ml/min did not reach statistical significance. Red blood cell binding of 99mTc-MAG3, 125I-OIH and 51Cr-EDTA was 2.0%, 14.6% and 0.2%, respectively. Protein binding of 99mTc-MAG3, 125I-OIH and 51Cr-EDTA was 86.3%, 61.1% and 5.9%, respectively. The volume of distribution of 99mTc-MAG3, 125I-OIH and 51Cr-EDTA was 16.3%, 27.0% and 19.4% of body weight. In conclusion, the clearances of 99mTc-MAG3 and 125I-OIH are more closely correlated than is the clearance of 99mTc-MAG3 with GFR. Extrarenal clearance of 99mTc-MAG3 is relatively smaller than extrarenal clearance of 51Cr-EDTA. Thus, plasma clearance of 99mTc-MAG3 can be used as a measure of renal tubular function.

Extensive thrombus formation with heparin resistance during extracorporeal circulation. A new presentation of familial antithrombin III deficiency.

Extensive thrombus formation during extracorporeal circulation despite the administration of heparin sodium prompted investigation of a 15-year-old boy with a calcified right ventricular thrombus and a history of subacute bacterial endocarditis. In vitro studies confirmed the failure of heparin in standard doses to have an anticoagulant effect. Antithrombin III concentrations were low. The patient's mother, who had no history of thromboembolic disease, was also antithrombin III deficient. Resistance to heparin is a theoretical, but inconsistently documented, feature of antithrombin III deficiency. This deficiency state should be considered whenever heparin resistance is encountered, even in the absence of a personal and family history of thromboses.

Temperature effects upon the time course of contraction and re-extension in Stentor coeruleus.

A double-flash microphotographic technique has been used to follow the variation with temperature of the following kinetic parameters related to the contraction and re-extension of the ciliate Stentor coeruleus, namely the rate of contraction, the initiation time before contraction, the rate of re-extension and the initiation time before re-extension, all described by first order kinetics. Activation enthalpies, entropies and free energies related to the above mentioned parameters were calculated from the variation of the rate constants with temperature. The enthalpies and entropies appear to be of minor interest compared to the free energies. For the contraction and the initiation of contraction the delta G transition state values obtained were 14 and 15 kcal/mole, respectively, while the re-extension and the initiation of re-extension both were represented by a value of delta G transition state about 19 kcal/mole. These results are compared to activation parameters for different motile systems and for the formation and breakdown of ATP-myosin complexes. A model for the contraction and re-extension processes is proposed in accordance with the results measured.

The effect of charatoxin, 4-methylthio-1,2-dithiolane, on the frog sartorius neuromuscular junction.

The insecticide 4-methylthio-1,2-dithiolane, named charatoxin, blocks the frog muscular twitches elicited through the neuromuscular junction. The activity level and the course of inhibition is comparable to that of 4-dimethyl-amino-1,2-dithiolane, nereistoxin.