Adjunctive rifampicin for Staphylococcus aureus bacteraemia (ARREST): a multicentre, randomised, double-blind, placebo-controlled trial.

BACKGROUND: Staphylococcus aureus bacteraemia is a common cause of severe community-acquired and hospital-acquired infection worldwide. We tested the hypothesis that adjunctive rifampicin would reduce bacteriologically confirmed treatment failure or disease recurrence, or death, by enhancing early S aureus killing, sterilising infected foci and blood faster, and reducing risks of dissemination and metastatic infection. METHODS: In this multicentre, randomised, double-blind, placebo-controlled trial, adults (≥18 years) with S aureus bacteraemia who had received ≤96 h of active antibiotic therapy were recruited from 29 UK hospitals. Patients were randomly assigned (1:1) via a computer-generated sequential randomisation list to receive 2 weeks of adjunctive rifampicin (600 mg or 900 mg per day according to weight, oral or intravenous) versus identical placebo, together with standard antibiotic therapy. Randomisation was stratified by centre. Patients, investigators, and those caring for the patients were masked to group allocation. The primary outcome was time to bacteriologically confirmed treatment failure or disease recurrence, or death (all-cause), from randomisation to 12 weeks, adjudicated by an independent review committee masked to the treatment. Analysis was intention to treat. This trial was registered, number ISRCTN37666216, and is closed to new participants. FINDINGS: Between Dec 10, 2012, and Oct 25, 2016, 758 eligible participants were randomly assigned: 370 to rifampicin and 388 to placebo. 485 (64%) participants had community-acquired S aureus infections, and 132 (17%) had nosocomial S aureus infections. 47 (6%) had meticillin-resistant infections. 301 (40%) participants had an initial deep infection focus. Standard antibiotics were given for 29 (IQR 18-45) days; 619 (82%) participants received flucloxacillin. By week 12, 62 (17%) of participants who received rifampicin versus 71 (18%) who received placebo experienced treatment failure or disease recurrence, or died (absolute risk difference -1·4%, 95% CI -7·0 to 4·3; hazard ratio 0·96, 0·68-1·35, p=0·81). From randomisation to 12 weeks, no evidence of differences in serious (p=0·17) or grade 3-4 (p=0·36) adverse events were observed; however, 63 (17%) participants in the rifampicin group versus 39 (10%) in the placebo group had antibiotic or trial drug-modifying adverse events (p=0·004), and 24 (6%) versus six (2%) had drug interactions (p=0·0005). INTERPRETATION: Adjunctive rifampicin provided no overall benefit over standard antibiotic therapy in adults with S aureus bacteraemia. FUNDING: UK National Institute for Health Research Health Technology Assessment

Bacterial pathogens and associated toxins involved in erythrophore cell aggregation

Current detection methods for bacterial contamination rely on structure based detection of proteins and nucleic acids. While these methods are easy to use and reliable, they cannot evaluate the toxicity of a sample and the potential to cause disease. Previously, erythrophore cells derived from Betta splendens had been suggested as a method to detect toxic agents such as chemicals and toxins. The work described here, investigated the potential of erythrophore cells as a detection method for the model food-associated pathogenic bacteria Salmonella enteritidis, Clostridium perfringens, Clostridium botulinum and Bacillus cereus. Erythrophore cell response to each bacterial pathogen was unique and could be distinguished from the bacterial growth medium. These results demonstrate that erythrophore cell response can be used to detect a set of pathogenic bacteria. A second focus of this research effort was to test the hypothesis that erythrophore cells respond to pathogenic bacteria differently then nonpathogenic bacteria. To test this hypothesis, erythrophore cells were exposed to pathogenic and nonpathogenic Bacillus strains. Erythrophore cells failed to respond to Bacillus subtilis and a nonpathogenic Bacillus anthracis vaccine strain. Erythrophore cells responded to members of the B. cereus group including: B. cereus ATCC 10987, B. cereus UW85, B. cereus ATCC 14579, emetic B. cereus NCTC 11143, and Bacillus thuringiensis subsp. kurstaki BGSC 4D1. A third focus of this research effort was to identify the bacterial virulence factor(s) responsible for inducing erythrophore cell response. Random chemical mutagenesis of B. cereus ATCC 49064 resulted in a single amino acid conversion of alanine to threonine at residue 289 of L2 toxin component of HBL. This mutation resulted in a delayed erythrophore cell response which was complemented with the wildtype hbl gene implementing the HBL toxin complex as a factor capable of inducing erythrophore cell response. In conclusion, this study demonstrates that erythrophore cells can be optically monitored to detect several different bacterial pathogens. From this work, the utility of erythrophore cell response can be expanded from function based detection to include studying toxin activity as well as how pathogenic bacteria interact with eukaryotic cells

Potential of the Melanophore Pigment Response for Detection of Bacterial Toxicity ▿

Chromatophore cells have been investigated as potential biodetectors for function-based detection of chemically and biologically toxic substances. Oncorhynchus tshawytscha (chinook salmon) melanophores, a chromatophore cell type containing brown pigment, rapidly detect the salmonid pathogens Aeromonas salmonicida, Yersinia ruckeri, and Flavobacterium psychrophilum and the human pathogen Bacillus cereus

Evaluating Composite Sampling Methods of <i>Bacillus</i> Spores at Low Concentrations

<div><p>Restoring all facility operations after the 2001 Amerithrax attacks took years to complete, highlighting the need to reduce remediation time. Some of the most time intensive tasks were environmental sampling and sample analyses. Composite sampling allows disparate samples to be combined, with only a single analysis needed, making it a promising method to reduce response times. We developed a statistical experimental design to test three different composite sampling methods: 1) single medium single pass composite (SM-SPC): a single cellulose sponge samples multiple coupons with a single pass across each coupon; 2) single medium multi-pass composite: a single cellulose sponge samples multiple coupons with multiple passes across each coupon (SM-MPC); and 3) multi-medium post-sample composite (MM-MPC): a single cellulose sponge samples a single surface, and then multiple sponges are combined during sample extraction. Five spore concentrations of <i>Bacillus atrophaeus</i> Nakamura spores were tested; concentrations ranged from 5 to 100 CFU/coupon (0.00775 to 0.155 CFU/cm²). Study variables included four clean surface materials (stainless steel, vinyl tile, ceramic tile, and painted dry wallboard) and three grime coated/dirty materials (stainless steel, vinyl tile, and ceramic tile). Analysis of variance for the clean study showed two significant factors: composite method (p< 0.0001) and coupon material (p = 0.0006). Recovery efficiency (RE) was higher overall using the MM-MPC method compared to the SM-SPC and SM-MPC methods. RE with the MM-MPC method for concentrations tested (10 to 100 CFU/coupon) was similar for ceramic tile, dry wall, and stainless steel for clean materials. RE was lowest for vinyl tile with both composite methods. Statistical tests for the dirty study showed RE was significantly higher for vinyl and stainless steel materials, but lower for ceramic tile. These results suggest post-sample compositing can be used to reduce sample analysis time when responding to a <i>Bacillus anthracis</i> contamination event of clean or dirty surfaces.</p></div

ANOVA results showing statistical significance for the tested factors and their interactions for clean coupon materials.

<p>ANOVA results showing statistical significance for the tested factors and their interactions for clean coupon materials.</p

The six experimental factors used in the study to evaluate recovery efficiency.

<p>The six experimental factors used in the study to evaluate recovery efficiency.</p

Grime coating on coupons is associated with an increased RE for stainless steel and vinyl coupons, but RE is reduced when grime is present on ceramic coupons.

<p>The presence of grime is an independent significant factor on RE. The interaction between material type and grime presence is also significant for RE.</p

Pictorial overview of the sample process and analysis method for each sampling sponge.

<p>*For sponges used with the multi-medium multi-pass composite (MM-MPC) method, each of the sponges used for sampling were extracted one at a time, in the same 90 mL buffer. ^#The volume following extraction was >90 mL (up to 105 mL) for MM-MPC samples; therefore, the sample was split into three aliquots prior to being combined. ^‡The final target volume for all methods was 6 mL, including the MM-MPC method.</p

ANOVA results for experiments with 16 locations composited using the MM-MPC method.

<p>ANOVA results for experiments with 16 locations composited using the MM-MPC method.</p

Pictorial overview of the sample process and analysis method for each sampling sponge.

<p>*For sponges used with the multi-medium multi-pass composite (MM-MPC) method, each of the sponges used for sampling were extracted one at a time, in the same 90 mL buffer. ^#The volume following extraction was >90 mL (up to 105 mL) for MM-MPC samples; therefore, the sample was split into three aliquots prior to being combined. ^‡The final target volume for all methods was 6 mL, including the MM-MPC method.</p