[Phenotypic methods for detection of methicillin-resistant Staphylococcus aureus]

BACKGROUND

Cefoxitin is a potent inducer of the mecA gene. It is currently as a screening recommended method for presumptive identification of isolates of methicillin resistant Staphylococcus aureus (MRSA). The aim of the study was to compare the sensitivity and specificity of the cefoxitin disc diffusion (30 μg) to oxacillin agar screening from detection of the mecA gene by PCR.

METHODS

Three hundred thirty-one strains of S. aureus isolated from blood cultures of patients from hospitals in Lima were used in the study. The following tests were performed: oxacillin screening agar (plates were inoculated with 4% NaCl and 6 mg/L of oxacillin), cefoxitin disc diffusion test (30 ug) and PCR to amplify the mecA gene.

RESULTS

The mecA gene was detected in 165 out of 331 S. aureus isolates. Thus, the frequency of detection of MRSA was 50%. The evaluation of the cefoxitin disc diffusion test showed a 96.3% and 90.9% of sensitivity and specificity, respectively.

CONCLUSION

Cefoxitin disc diffusion test correlated well with detection of the mecA gene by PCR. Therefore, this test can be an alternative to PCR for detection of MRSA in limited resources settings.

Validation of an apicoplast genome target for the detection of Plasmodium species using polymerase chain reaction and loop mediated isothermal amplification

The genome of the Plasmodium apicoplast, which has a higher copy number compared with current targets for molecular diagnosis of malaria, appears to be a suitable target for detection of submicroscopic infections that are capable of sustaining transmission. Novel primers targeting a conserved segment of the apicoplast (PFC10_AP|0010:rRNA) were designed and used in a number of different high throughput platforms such as single-step PCR (ssPCR), nested PCR (nPCR) and loop-mediated isothermal amplification (LAMP) for parasite detection. Replicates of ten-fold serial dilutions of Plasmodium falciparum 3D7 DNA, with equivalent parasite density ranges of 200,000 to 0.2 parasites/μL, were used to determine the limit of detection and repeatability of each assay. A panel of 184 archived DNA samples extracted from either EDTA whole blood or dried blood spots, from across West Africa and South East Asia was used to determine the diagnostic performance of the assays. All assays amplified the 2 parasites/μL dilution except the ssPCR, which amplified two of the three replicates. Using an 18S rRNA PCR as reference, the sensitivity was 98% (95% CI 93-100%) for the LAMP assay, 87% (95% CI 79-93%) for ssPCR and 100% (95% CI 97-100%) for nPCR. Specificity was 91% (95% CI 83-96%) for LAMP, 82% (95% CI 72-90%) for ssPCR and 66% (95% CI 54-76%) for nPCR. The apicoplast genome-based nPCR detected more positive samples overall than the reference method. Discrepant samples were confirmed as true positives using a probe-based real-time quantitative PCR assay. The results show that the apicoplast genome is a suitable target for molecular diagnosis of malaria.

Amphiphilic glycosylated block copolypeptides as macromolecular surfactants in the emulsion polymerization of styrene

Bio-inspired amphiphilic block copolymer surfactants fully derived from amino acids and sugars are synthesised. The materials are successfully employed in the synthesis of polystyrene latexes by emulsion polymerization.

Assessment of readiness for clinical decision support to aid laboratory monitoring of immunosuppressive care at U.S. liver transplant centers

BACKGROUND

Following liver transplantation, patients require lifelong immunosuppressive care and monitoring. Computerized clinical decision support (CDS) has been shown to improve post-transplant immunosuppressive care processes and outcomes. The readiness of transplant information systems to implement computerized CDS to support post-transplant care is unknown.

OBJECTIVES

a) Describe the current clinical information system functionality and manual and automated processes for laboratory monitoring of immunosuppressive care, b) describe the use of guidelines that may be used to produce computable logic and the use of computerized alerts to support guideline adherence, and c) explore barriers to implementation of CDS in U.S. liver transplant centers.

METHODS

We developed a web-based survey using cognitive interviewing techniques. We surveyed 119 U.S. transplant programs that performed at least five liver transplantations per year during 2010-2012. Responses were summarized using descriptive analyses; barriers were identified using qualitative methods.

RESULTS

Respondents from 80 programs (67% response rate) completed the survey. While 98% of programs reported having an electronic health record (EHR), all programs used paper-based manual processes to receive or track immunosuppressive laboratory results. Most programs (85%) reported that 30% or more of their patients used external laboratories for routine testing. Few programs (19%) received most external laboratory results as discrete data via electronic interfaces while most (80%) manually entered laboratory results into the EHR; less than half (42%) could integrate internal and external laboratory results. Nearly all programs had guidelines regarding pre-specified target ranges (92%) or testing schedules (97%) for managing immunosuppressive care. Few programs used computerized alerting to notify transplant coordinators of out-of-range (27%) or overdue laboratory results (20%).

CONCLUSIONS

Use of EHRs is common, yet all liver transplant programs were largely dependent on manual paper-based processes to monitor immunosuppression for post-liver transplant patients. Similar immunosuppression guidelines provide opportunities for sharing CDS once integrated laboratory data are available.

Fatal Chromobacterium violaceum bacteraemia in rural Bandundu, Democratic Republic of the Congo

We describe the first case of bacteraemia caused by Chromobacterium violaceum in the Democratic Republic of the Congo. This diagnosis was made in an apparently healthy adult who was admitted to a rural hospital of the province of Bandundu with severe community-acquired sepsis. The patient developed multi-organ failure and died; to our knowledge, this is the first reported fatal case in an adult in Africa.

Abcc10 status affects mammary tumour growth, metastasis, and docetaxel treatment response

Background:

Resistance to chemotherapeutic agents is a major obstacle to cancer treatment. A group of ABC efflux pumps, the Multidrug Resistance Proteins, is a source of resistance. Herein, we investigated the role of ABCC10 in mammary tumours, given the important role we have defined for ABCC10 in transporting taxanes, and the recognition that some ABCC proteins have roles in tumour growth.

Methods:

ABCC10 expression was correlated to human breast cancer subtype using breast tissue microarrays. Real-time quantitative PCR and western blot analysis were used to examine ABCC10 expression in human breast cancer lines. Abcc10^−/− mice were crossed to MMTV-PyVmT mice to produce Abcc10^−/−vs Abcc10^+/+ mammary tumours and derivative cell lines. We used allograft and cellular assays to perform baseline and drug sensitization analysis of tumours and cell lines.

Results:

Clinical sample analyses indicated that ABCC10 was more highly expressed in Her2+ and ER+ than in Her2−, ER−, and triple-negative breast cancer. Unexpectedly, PyVmT; Abcc10^−/− tumours grew more rapidly than PyVmT; Abcc10^+/+ tumours and were associated with significantly reduced apoptosis and metastasis. PyVmT; Abcc10^−/− lines were less migratory than PyVmT; Abcc10^+/+ lines. Finally, we showed increased survival of docetaxel-treated MMTV-PyVmT; Abcc10^−/− mice compared with wild-type mice.

Conclusions:

These data identify roles for Abcc10 in breast cancer pathogenesis and in vivo docetaxel resistance.

Species distribution and antifungal susceptibility profile of Candida isolates from bloodstream infections in Lima, Peru

Yeast identification and in vitro susceptibility testing provide helpful information for appropriate administration of antifungal treatments; however, few reports from the Latin American region have been published. The aim of this study was to identify the species present in isolates from bloodstream infections diagnosed in nine hospitals in Lima, Peru and to determine their in vitro susceptibility to four antifungal drugs. We tested and identified 153 isolates collected between October 2009 and August 2011 using standard methods. PCR and PCR-RFLP assays were performed to distinguish Candida albicans from Candida dubliniensis and to identify species of the Candida parapsilosis and Candida glabrata complexes. Antifungal susceptibility testing for fluconazole, anidulafungin and voriconazole was performed using the CSLI M27-A3 method, and amphotericin B susceptibility was determined using the Etest method. The most frequently isolated species were: C. albicans (61; 39.9 %), C. parapsilosis (43; 28.1 %), C. tropicalis (36; 23.5%) and C. glabrata (8; 5.2 %). The overall susceptibility rates were 98.0 %, 98.7 %, 98.0 % and 97.4 % for amphotericin B, fluconazole, voriconazole and anidulafungin, respectively. No isolate was resistant to more than one drug. These results showed that the rate of resistance to four antifungal drugs was low among Candida bloodstream isolates in Lima, Peru.

Methods for implantation of micro-wire bundles and optimization of single/multi-unit recordings from human mesial temporal lobe

OBJECTIVE

The authors report methods developed for the implantation of micro-wire bundles into mesial temporal lobe structures and subsequent single neuron recording in epileptic patients undergoing in-patient diagnostic monitoring. This is done with the intention of lowering the perceived barriers to routine single neuron recording from deep brain structures in the clinical setting.

APPROACH

Over a 15 month period, 11 patients were implanted with platinum micro-wire bundles into mesial temporal structures. Protocols were developed for (A) monitoring electrode integrity through impedance testing, (B) ensuring continuous 24-7 recording, (C) localizing micro-wire position and 'splay' pattern and (D) monitoring grounding and referencing to maintain the quality of recordings.

MAIN RESULTS

Five common modes of failure were identified: (1) broken micro-wires from acute tensile force, (2) broken micro-wires from cyclic fatigue at stress points, (3) poor in vivo micro-electrode separation, (4) motion artifact and (5) deteriorating ground connection and subsequent drop in common mode noise rejection. Single neurons have been observed up to 14 days post-implantation and on 40% of micro-wires.

SIGNIFICANCE

Long-term success requires detailed review of each implant by both the clinical and research teams to identify failure modes, and appropriate refinement of techniques while moving forward. This approach leads to reliable unit recordings without prolonging operative times, which will help increase the availability and clinical viability of human single neuron data.

Dietary practices in pyridoxine non-responsive homocystinuria: a European survey

BACKGROUND

Within Europe, the management of pyridoxine (B6) non-responsive homocystinuria (HCU) may vary but there is limited knowledge about treatment practice.

AIM

A comparison of dietetic management practices of patients with B6 non-responsive HCU in European centres.

METHODS

A cross-sectional audit by questionnaire was completed by 29 inherited metabolic disorder (IMD) centres: (14 UK, 5 Germany, 3 Netherlands, 2 Switzerland, 2 Portugal, 1 France, 1 Norway, 1 Belgium).

RESULTS

181 patients (73% >16 years of age) with HCU were identified. The majority (66%; n=119) were on dietary treatment (1-10 years, 90%; 11-16 years, 82%; and >16 years, 58%) with or without betaine and 34% (n=62) were on betaine alone. The median natural protein intake (g/day) on diet only was, by age: 1-10 years, 12 g; 11-16 years, 11 g; and >16 years, 45 g. With diet and betaine, median natural protein intake (g/day) by age was: 1-10 years, 13 g; 11-16 years, 20 g; and >16 years, 38 g. Fifty-two percent (n=15) of centres allocated natural protein by calculating methionine rather than a protein exchange system. A methionine-free l-amino acid supplement was prescribed for 86% of diet treated patients. Fifty-two percent of centres recommended cystine supplements for low plasma concentrations. Target treatment concentrations for homocystine/homocysteine (free/total) and frequency of biochemical monitoring varied.

CONCLUSION

In B6 non-responsive HCU the prescription of dietary restriction by IMD centres declined with age, potentially associated with poor adherence in older patients. Inconsistencies in biochemical monitoring and treatment indicate the need for international consensus guidelines.