An outbreak of livestock-associated meticillin-resistant Staphylococcus aureus (LA-MRSA) clonal complex 398 in a regional burns centre.

BACKGROUND: Meticillin-resistant Staphylococcus aureus (MRSA) outbreaks have been reported previously in burns centres with resulting mortality and morbidity. This article describes the first human-associated outbreak in the UK caused by a strain of mupirocin-resistant (MuR) livestock-associated MRSA clonal complex 398 (LA-MRSA CC398) in an adult burns centre. The centre historically had a very low prevalence of MRSA infections. AIM: To describe the clinical and epidemiological context of how the outbreak was identified and contained using a range of infection prevention and control (IPC) measures guided by both traditional and genetic methods. METHODS: A cluster of MuR-MRSA led to an outbreak investigation. Cases were detected via retrospective search and real-time laboratory surveillance. Isolates were sent continuously for whole-genome sequencing (WGS). A live timeline of cases and interventions was produced throughout the period. FINDINGS: The outbreak consisted of 12 cases (seven males and five females) aged between 22 and 70 years. Patients were identified between May and October 2020. All patients were colonized rather than infected. The strain acquired the plasmid bearing MupA while colonizing the index case before dissemination. The index case was found to be a chicken farmer. This outbreak was eventually controlled using IPC measures, audits, and blind staff decolonization guided by insight from WGS. CONCLUSION: It was not possible to determine how the strain entered the centre, or if a staff carrier was involved. The outbreak demonstrated the potential for continued transmissions for months despite active surveillance and stringent control measures.

The burden of healthcare-associated Clostridium difficile infection in a non-metropolitan setting.

OBJECTIVE: Healthcare-associated Clostridium difficile infection (HCA-CDI) remains a major cause of morbidity and mortality in industrialized countries. However, few data exist on the burden of HCA-CDI in multi-site non-metropolitan settings. This study examined the introduction of an antimicrobial stewardship programme (ASP) in relation to HCA-CDI rates, and the effect of HCA-CDI on length of stay (LOS) and hospital costs. METHODS: A comparative before-and-after intervention study of patients aged ≥16 years with HCA-CDI from December 2010 to April 2016 across the nine hospitals of a non-metropolitan health district in New South Wales, Australia was undertaken. The intervention comprised a multi-site ASP supported by a clinical decision support system, with subsequent introduction of email feedback of HCA-CDI cases to admitting medical officers. MAIN OUTCOME MEASURES: HCA-CDI rates, comparative LOS and hospital costs, prior use of antimicrobials and proton pump inhibitors, and appropriateness of CDI treatment. RESULTS: HCA-CDI rates rose from 3.07 to 4.60 cases per 10,000 occupied bed-days pre-intervention, and remained stable at 4 cases per 10,000 occupied bed-days post-intervention (P=0.24). Median LOS (17 vs six days; P<0.01) and hospital costs (AU$19,222 vs $7861; P<0.01) were significantly greater for HCA-CDI cases (N=91) than for matched controls (N=172). Half of the patients with severe HCA-CDI (4/8) did not receive initial appropriate treatment (oral vancomycin). CONCLUSIONS: HCA-CDI placed a significant burden on the regional and rural health service through increased LOS and hospital costs. Interventions targeting HCA-CDI could be employed to consolidate the effects of ASPs.

Reconstruction of the temporomandibular joint by the transfer of the free vascularised second metatarsal.

We present our experience of a series of patients who presented for salvage reconstruction of the temporomandibular joint (TMJ) for relief of pain. Reconstruction was achieved by transfer of the free vascularised second metatarsal. This technique has been used for a total of seven TMJ reconstructions in five patients. We describe the surgical anatomy, technique and results during the last 18 years. One joint failed but the other six surviving joints continue to provide adequate pain-free function. We advocate this technique for autogenous salvage reconstruction in joints that have been previously operated on unsuccessfully.

Castleman's disease presenting as a midline neck mass.

We report the case of a 13-year-old girl who presented with a painless midline submental mass. Excision biopsy confirmed Castleman's disease of the hyaline-vascular type. This unusual condition needs to be considered in the differential diagnosis of masses arising in the neck.

Multiple aneurysms associated with congenital rubella.

We describe the case of a woman with congenital rubella who presented with backache. Plain abdominal X-ray revealed calcification of a superior mesenteric artery aneurysm. Intra-arterial digital subtraction angiography demonstrated multiple aneurysms of the arteries to the upper and lower limbs and the viscera. We have not found another report in the literature of the association of congenital rubella with multiple aneurysms.

Repair of secondary aortoesophageal fistula by endoluminal stent-grafting.

PURPOSE: To describe a case of secondary aortoesophageal fistula that was treated with an endoluminal stent-graft. CASE REPORT: A 58-year-old woman presented with hematemesis and melena. In 1974 she had an interposition graft repair of an aortic transection sustained during a traffic accident. At the examination in 1998, angiography demonstrated a mechanical disruption of the proximal anastomosis forming an aortoesophageal fistula. A 28-mm x 3.75-cm AneuRx stent-graft was introduced via a right femoral arteriotomy and deployed across the defect. Follow-up CT scans at 18 months showed exclusion of the false aneurysm with no evidence of infection; the patient remains well at >2 years after stent-graft implantation. CONCLUSIONS: Endoluminal repair can be successful in achieving a satisfactory midterm outcome in cases of secondary aortoesophageal fistula.

A phase I/II study of vinorelbine, doxorubicin, and methotrexate with leucovorin rescue as first-line treatment for metastatic breast cancer.

PURPOSE: This study was performed to determine the maximum tolerated dose (MTD) and toxicity of vinorelbine when used in combination with doxorubicin and methotrexate with leucovorin rescue in women with metastatic breast cancer. METHODS: Enrolled in the study were 23 women with metastatic breast cancer who had not received prior chemotherapy for metastatic disease. Patients treated at the first dose level received vinorelbine 20 mg/m2 on day 1, doxorubicin 40 mg/m2 on day 1, methotrexate 100 mg/m2 on day 1 and leucovorin 20 mg orally every 6 h for six doses beginning on day 2. Treatment was repeated every 21 days. The vinorelbine dose was escalated by 5 mg/m2 for patients treated at subsequent dose levels. The MTD was defined as the dose level at which fewer than one-third of patients enrolled experienced dose-limiting toxicity (DLT). When the MTD of vinorelbine had been determined, the doxorubicin dose was then escalated by 10 mg/m2 with the vinorelbine dose held at its MTD. RESULTS: total of 98 courses of treatment (median of 4 per patient, range 2-8) were administered. The MTD of this regimen was found to be vinorelbine 25 mg/m2, doxorubicin 40 mg/m2, and methotrexate 100 mg/m2 with leucovorin rescue. At higher doses of vinorelbine, neutropenia, fatigue, arm pain, malaise, nausea and vomiting were dose-limiting. Higher doses of doxorubicin resulted in universal dose limiting neutropenia, and frequent nonhematologic DLT consisting of arm pain, malaise, stomatitis, nausea and vomiting. Amongst the 20 patients with measurable disease, there were 3 complete responses (15%, 95% confidence interval 3%-38%), 5 partial responses (25%, 95% confidence interval 9%-49%) and an overall response rate of 40% (95% confidence interval 19%-64%). The median survival was estimated to be 25 months from the start of chemotherapy. CONCLUSIONS: Vinorelbine at 25 mg/m2 can be safely administered with doxorubicin at 40 mg/m2 and methotrexate at 100 mg/m2 with leucovorin rescue. Response rates observed with this regimen suggest that this combination of chemotherapeutic agents may not be more effective than the combination of vinorelbine and doxorubicin.

Inhibition of PAF-induced human platelet aggregation by antithrombotic nipecotomides.

Nipecotamides (piperidine-3-carboxamides) are potent inhibitors of platelet aggregation induced by a variety of agonists in vitro and in vivo. The inhibitory effects of six structural types of nipecotamides on human platelet aggregation induced by platelet-activating factor (PAF) in vitro, are studied. Evaluation of 15 racemates and stereoisomers of two nipecotamides showed that bis-nipecotoyl alkanes were more active than their mono congeners. Mono- and bis-nipecotoyl decanes were more potent than the corresponding hexanes. Lipophilicity was found to play a significant role in the antiplatelet activity of these compounds. The stereoselectivity in the PAF-antagonist potential of nipecotamides was less pronounced than that resulting from their action on ADP- or collagen-induced aggregation. Oxidation of the two benzylic carbon atoms of alpha, alpha'-bis[3-(N,N-diethylcarbamoyl)piperidino]-p-xylene.2HBr (A-1) to form 1,4-bis[3-N,N-diethylcarbamoyl) piperidino]benzenedicarboxamide (A-40K), which has a second set of carbonyl oxygens but lacks basic N atoms, resulted in a remarkable loss of ADP-antagonist potency while retaining PAF-antagonist activity. It is suggested that in addition to their membrane effects, nipecotamides act at other sites, including the PAF receptor. Double reciprocal plots of PAF binding to gel-filtered platelets (GFP) in the presence and absence of a typical nipecotamide (A-1C) were indicative of competitive inhibition (Ki = 19.28 microM). Scatchard analysis of 3H-PAF binding to GFP suggested the presence of high, intermediate (I) and low affinity binding sites, of which the I site gave a KD/app of 0.332 nM with an estimated 564 sites/platelet. Key interactions of nipecotamides with the PAF receptor appear to be the following (i) electrostatic interactions of the two amide oxygens with a primary set of electropositive areas spaced at 5-7 A, (ii) in the case of appropriate compounds, electrostatic interactions of the two amide oxygens spaced at 10-12 A with corresponding secondary receptor sites carrying positive electrostatic potential, (iii) a hydrophobic moiety fitting into a hydrophobic pocket in the receptor, and (iv) the cationic piperidine N+ (at pH 7.4) interacting with a counterion, probably aspartic acid.

Design and synthesis of piperidine-3-carboxamides as human platelet aggregation inhibitors.

A detailed structure-activity analysis was carried out using eight 1-alkyl(aralkyl)nipecotamides (type 5), 33 bis-nipecotamidoalkanes and aralkanes (type 6), and 7 N,N'-bis(nipecotoyl)-piperazines (type 7) as inhibitors of human platelet aggregation. Steric factors played an important role in determining the activity of type 5 compounds possessing an an appropriate degree of hydrophobic character. Types 6 and 7 compounds were more potent than the corresponding type 5 molecules. Hydrophobic character appeared to influence the activity of type 6 compounds. A 3-substituent on the piperidine ring was necessary for antiplatelet activity; the substituent should be preferably an amide with its C attached directly to the ring. 3,5-Disubstitution and 2-substitution led to a decline in activity. Optimal activity was attained when the two nipecotoyl ring N atoms were connected by an aralkyl group, and separated by approximately 7 A. It is suggested that van der Waals forces and pi interactions may govern the inhibitor-platelet interaction. The most potent type 6 inhibitor was alpha,alpha'-bis[3-(N-ethyl-N-butylcarbamoyl)piperidino]-p-xylene (6i). The most potent type 5 compound was 1-decyl-3-(N,N-diethylcarbamoyl)piperidine (5a). Any substitution on the piperazine ring of type 7 compounds led to a decline in activity, the most active analog being N,N'-bis(1-decylnipecotoyl)piperazine (7a). It is suggested that nipecotamides interact with anionic platelet sites located 7 A from each other and connected by a hydrophobic well.

Synergistic antiplatelet effects of a nipecotamide A-1C and low dose aspirin.

1. The effects of an antithrombotic nipecotamide, A-1, and aspirin were examined separately and in combination, on human platelet aggregation in vitro and on collagen+epinephrine-induced thromboembolic death of mice in vivo. 2. Concurrent addition of the two agents to a platelet suspension resulted in a supraadditive inhibition. Racemic A-1 and its meso diastereomer A-1C behaved similarly in this respect. The IC50 value of rac. A-1 declined from 46.25 to 18.4 microM in the presence of aspirin. 3. In vivo, concurrent administration of A-1C and aspirin produced significant potentiation of antithrombotic activity. A 2-fold reduction in the ED50 of A-1C occurred when it was coadministered with aspirin to mice; also, the toxicity reduced slightly, increasing the therapeutic index by a factor of 2.2. 4. The design and synthesis of new compounds possessing the structural features of the two molecules appears to provide superior antithrombotic agents.

Inhibition of agonist-induced rise in platelet Ca2+ by antithrombotic nipecotamides.

The effects of three structural types of nipecotamides and their stereoisomers on collagen-induced aggregation and intraplatelet ionized calcium ([Ca2+]i) rise in human platelets were evaluated using aequorin as the [Ca2+]i indicator. The orders of potencies of racemic nipecotamides were different when collagen was the agonist compared with those obtained using ADP. It is suggested that in addition to their earlier hypothesized interactions with platelet anionic phospholipids of the plasma and organelle membranes, nipecotamides may, in addition, act at other receptor sites. In general, the inhibition of collagen-induced aggregation paralleled their inhibitory effects on the rise of [Ca2+]i. The compounds were stereoselective in inhibiting aggregation as well as [Ca2+]i rise. The meso diastereomers of I and II were more potent than the corresponding enantiomeric pairs. A single [Ca2+]i peak was noticed when the incubate contained 1.0 mM extracellular calcium [Ca2+]o. On the other hand a biphasic [Ca2+]i rise was noticed when the nominally Ca(2+)-free buffer contained 75 microM ethylene glycol tetraacetate (EGTA). The first peak corresponded with platelet shape change, suggesting Ca2+ discharge from internal stores, and the second, with aggregation. The second peak may reflect either Ca2+ flux across the plasma membrane or aequorin leak from internal cellular locations or from the canicular system. Inhibition of the rise in intraplatelet Ca2+ appears to be associated with the platelet aggregation-inhibitory actions of nipecotamides.

Enantioselective antiplatelet actions of nipecotamides.

Two synthetic racemic nipecotamides, 1-decyl-3-(N,N- diethylcarbamoyl)piperidine hydrobromide (1) and alpha, alpha'-bis[3-(N-benzyl-N-methylcarbamoyl)piperidino]-p-xylene dihydrobromide (2) were resolved on a chiral alpha 1-acid glycoprotein semipreparative HPLC column. Thus, rac.1 was resolved into two enantiomers 1A-(+) and 1B-(-); rac.2 was separated into the optical antipodes 2A-(-) and 2C-(+), and the meso diastereomer 2B-(0). Also on a preparative scale, 97% pure 2C was obtained via diastereomeric salt formation using dibenzoyl-L-(-)-tartaric acid. The individual isomers were evaluated for their platelet aggregation inhibitory potency. In inhibiting ADP-induced aggregation of human platelets in vitro, 1B-(-) was 4 times more potent than its optical antipode 1A-(+), and 2C-(+) was 6 times as active as 2A-(-); the meso diastereomer 2B-(0) had intermediate activity. With collagen as the 1B-(-) was twice as active as 1A-(+), and 2C-(+), the most active compound in this series (IC50 = 0.96 microM), was 10 times more potent than its antipode 2A-(-). Again, the meso diastereomer 2B-(0) had intermediate activity. These results demonstrate the enantioselective antiplatelet actions of mono- and bis- nipecotamide derivatives.

In vitro and in vivo activities of the novel antiplatelet agent alpha,alpha'-bis[3-(N,N-diethylcarbamoyl)piperidino]-p-xylene dihydrobromide.

In an effort to develop compounds with high antithrombotic activity and minimal toxicity, our laboratory has synthesized a number of nipecotamides. The effectiveness of one of these compounds, alpha,alpha'-bis[3-(N,N-diethylcarbamoyl)piperidino]-p-xylene dihydrobromide (A-1), in inhibiting both in vitro and in vivo platelet aggregation is reported here, along with its acute toxicity. The IC50 of A-1 in in vitro ADP- and PAF-induced platelet aggregation was 44.5 microM and 21.2 microM, respectively. Suppression of intraplatelet [Ca2+] is suggested as a likely mediator of the aggregation-inhibitory properties of A-1, since both the release of cytosolic Ca2+ and the influx of extracellular Ca2+ were decreased. The ED50 of A-1 in protecting mice against thromboembolism induced by a collagen-epinephrine challenge was 164 mumol/kg. The measurement of the acute toxicity of this compound as the LD50 was 691 mumol/kg, with the therapeutic index being 4.2. These data indicate that compounds in this family hold promise as clinically effective antithrombotic agents.

Molecular determinants of the platelet aggregation inhibitory activity of carbamoylpiperidines.

A series of alpha,alpha'-bis[3-(N,N-dialkylcarbamoyl)piperidino]-p- xylenes were synthesized and tested for their inhibitory activity on ADP-induced aggregation of human platelets. A parabolic curve was obtained when log 1/C (activity) was plotted against log P (octanol/water partition coefficient). Using this as a model, a new analogue, alpha,alpha'-bis-[3-(N-methyl-N-butylcarbamoyl)piperidino]-p-xylen e (3g), was synthesized with a predicted IC50 of 25 microM. When this compound was subsequently evaluated, the IC50 was 22.1 +/- 5.5 microM, demonstrating the applicability of this model. The amide oxygen of the carbamoyl substituent appeared necessary for activity. Thus, for example, when the amide carbonyl group of 3a (IC50 = 44.5 microM) was reduced to CH2, the resulting compound 4 had a dramatically reduced activity, IC50 = 1565 microM. Compound 3a was resolved into (+) and (-) enantiomers and a meso (0) diastereomer using fractional crystallization, diastereomeric tartrate formation, and chiral HPLC. Compared to (-)-3a, the (+) isomer was 15 times more potent when ADP was the agonist and 19 times more active when collagen was used as the agonist. Molecular modeling of R,R- and S,S-3a using the SYBYL program was used to examine their interactions with phosphatidylinositol (PI). There was a better fit between PI and the R,R-3a with the energy of interaction being 17.6 kcal/mol less than that of the S,S-3a/PI complex. Although the absolute stereochemistry of individual enantiomers is not known, this study shows that R,R-3a interacts more favorably with PI than does S,S-3a and that (+)-3a is a more potent inhibitor of human platelet aggregation than (-)-3a. It is postulated that because of their lipophilicity, these compounds penetrate the platelet membrane and are then protonated at the pH of the cytosol. The protonated N then neutralizes the anionic charge on the membrane phosphoinositides, thereby rendering them less susceptible to hydrolysis by phospholipase C. Thus, the determinant parameters for optimum antiplatelet activity in 3-carbamoylpiperidines are (1) the amide carbonyl, (2) appropriate stereochemistry of the 3-substituent and (3) a log P value of about 4.5.

Cytosolic ionized calcium in human platelets: the influence of collagen and a novel antiplatelet agent.

Two phases of calcium mobilization were observed when aequorin-loaded human platelets, suspended in a nominally calcium-free medium containing 0.1 mM EGTA, were stimulated with collagen. The first phase coincided with platelet shape change, and the second phase corresponded to aggregation. On the other hand, only one [Ca2+]i peak was found in systems containing 1.0 mM Ca, or 1.0 or 2.0 mM EGTA. A novel antiplatelet compound alpha,alpha'-bis [3-(N,N-diethylcarbamoyl)piperidino]-p-xylene dihydrobromide, inhibited both [Ca2+]i peaks. It is suggested that inhibition of the mobilization of intraplatelet calcium stores as well as the blocking of transmembrane calcium flux may be responsible for the platelet aggregation-inhibitory action of this compound.

The effect of carbamoylpiperidine and nipecotoylpiperazine analogs on ADP-stimulated human thrombocyte aggregation and platelet factor 3 availability.

There is a striking congruence between the inhibitory effects of three synthetic entities on ADP-induced (i) human blood platelet aggregation and (ii) platelet factor 3 availability as evidenced by prolonged 'Stypven time'. The pronounced parallel between each compound's potency in inhibiting aggregation (e.g. IA 48.9 +/- 1.3, S.E., %; n = 16) and in impeding platelet factor 3 availability (e.g. IPF-3av 42.3 +/- 2.5, S.E., %; n = 12), determined concurrently in platelet-rich plasma of four different donors, further substantiates that the antiplatelet activity of our carbamoylpiperidine and nipecotoylpiperazine congeners is exerted through their interaction with anionic phospholipids.

Some novel inhibitors of platelet aggregation: acute toxicity in mice and its relationship to in vitro efficacy and toxicity. II. Nipecotoylaminoalkane and nipecotoylpiperazine congeners.

Four closely related nipecotoyl congeners are employed as molecular probes to evaluate the effects of systematic molecular changes upon lethal potency of the compounds. The in vivo toxicities, effected by changes in molecular structure, are compared to their in vitro concentrations inhibiting ADP-induced aggregation and epinephrine-induced primary aggregation of human blood platelets and their toxicities to mouse fibroblasts (L-929 cells) in culture. To assist in the selection of compounds which offer the greatest promise as therapeutic agents for further evaluation and to guide future development of optimal molecular structures, a ratio of acute ip LD50 (mumol/kg) [Tm] to concentration inhibiting 50% ADP-induced platelet aggregation (mumol/liter) [A] is calculated for each compound. These ratios range from 2.41 to 24.92 for the four compounds included in this study.

Relationships between chemical structure and inhibition of epinephrine-induced human blood platelet aggregation.

The effect of structural features in a series of carbamoylpiperidine and nipecotoylpiperazine congeners on epinephrine-induced aggregation of human blood platelets is examined. Epinephrine-induced primary aggregation is effectively inhibited by the nipecotoylpiperazine derivatives (culminating at an IPA50 of 11.9 microM). While among nipecotoylpiperazine as well as carbamoylpiperidine congeners there are potent inhibitors of ADP-stimulated platelet function (cresting at an IA50 of 12.4 and 11.4 microM, respectively), the carbamoylpiperidine analogs are much less active (e.g., IPA50 of 298.1), or practically inactive, in impeding epinephrine-induced primary aggregation (PA).

Relationships between chemical structure and inhibition of ADP-stimulated human thrombocyte release of serotonin and platelet factor 4.

The inhibitory potencies of carbamoylpiperidinoalkane and N-alkylnipecotoylpiperazine derivatives on ADP-stimulated human blood platelet aggregation, serotonin (5-HT) release and platelet factor 4 (PF-4) release were evaluated. The procedure was designed to allow concurrent determination of all three sets of values. Most compounds were more than twice as potent in blocking PF-4 (X = 91 +/- 1 (S.E., n = 7)%) compared to their inhibition of 5-HT (X = 38 +/- 1(S.E., n = 6)%) release; the one compound which failed to meet these criteria was still decidedly more powerful in impeding PF-4 than 5-HT release. Since the compounds' platelet aggregation-inhibitory values were within the same range as their 5-HT release-blocking potencies, but had a strikingly greater impact in arresting PF-4 release, it is suggested that the platelet plasma membrane and the lining enveloping the dense bodies may share certain commonalities, while the sheathing encasing the alpha-granules may differ from both in a tangible manner.