299S1 DGHM Abstracts

Abstract

To improve the clinical outcome of Staphylococcus aureus septicaemia, early selection of appropriate antibiotic treatment is crucial. Molecular diagnostics represent an attractive approach for rapid identification of S. aureus and determination of its methicillin resistance. In direct comparison with other molecular assays (sa442 and mecA real time PCRs) and standard laboratory procedures, we evaluated the BD GeneOhm TM StaphSR assay for its use in the detection of S. aureus and methicillin-resistant S. aureus (MRSA) staphylococci from spiked blood culture bottles (n=134). In case of detecting S. aureus (n=90; MSSA: n=45, MRSA: n=45), the BD GeneOhm TM StaphSR assay had a sensitivity and a specificity of 100% each [95%-confidence interval (CI): 96.0%-100% and 82.4%-100%, respectively]. For MRSA (n=45), the test was 95.6% (95%-CI: 84.9%-99.5%) sensitive and 95.3% (95%-CI: 86.9%-99.0%) specific. Overall, 5 discrepant results arose with this assay due to the presence of methicillin-susceptible, revertant MRSA strains (3/45) and MRSA strains undetected with the BD GeneOhm TM StaphSR assay (2/45). Compared to other real-time-PCR based molecular approaches and to conventional standard laboratory methods, the BD GeneOhm TM StaphSR turned out to be an appropriate diagnostic tool for a rapid (~1.5 hours), preliminary identification of S. aureus and MRSA from blood cultures.Bacterial contamination is currently the major infectious hazard of platelet transfusion. The detection of bacterial contamination in platelet concentrates (PCs) has been implemented in several blood services as a routine quality control testing, but to date transfusion-transmitted bacterial sepsis has not been completely prevented. In the present study, a novel flow cytometry-based method was developed for the rapid point-of-issue screening of PCs for bacterial contamination. The BactiFlow flow cytometer was used to detect and count bacteria based on esterase activity in viable cells. A protocol for bacterial screening of PCs was established by enzymatic digestion and centrifiltration for the elimination of viable platelets and selective labeling of bacteria with a fluorescent esterase substrate. Results from the BactiFlow (Counts/mL) showed an excellent correlation to plate count results (CFU/mL). The lower detection limit of the assay was determined to 150 CFU/mL, whereas the time-to result was less than 1 hour. We investigated this new application in comparison to incubation (BacT/Alert culture system) and rapid nucleic acid-based or immunoassay detection methods (RT-PCR, Pan Genera Detection Technology). Our study demonstrates that the BactiFlow assay is most suitable for rapid bacterial screening of PCs and fulfils the requirements for a point-of-issuetesting of PCs with acceptable time-to-result, specificity, sensitivity and costs.

Understanding the Role of Host Hemocytes in a Squid/Vibrio Symbiosis Using Transcriptomics and Proteomics

“…Invertebrates, which comprise the vast majority of animals, lack an adaptive immune system and must rely solely on innate immunity to interface with a microbial world. Despite any obvious mechanism to achieve the precision with which the adaptive immune system targets specific pathogens, there are many examples of highly specific associations formed between microorganisms and invertebrates (e.g., as found in insect bacteriocytes, termite hindguts, the trophosomes of hydrothermal vent tubeworms, and the light organs of squids; Nyholm and McFall-Ngai, 2004 ; Stewart and Cavanaugh, 2006 ; Moran et al, 2008 ; Feldhaar and Gross, 2009 ; Watanabe and Tokuda, 2010 ). What are the mechanisms for achieving such specificity?…”

One nutritional symbiosis begat another: Phylogenetic evidence that the ant tribe Camponotini acquired Blochmannia by tending sap-feeding insects

“…An estimated 10-20% of insect species, in several taxonomic orders, depend on intracellular bacterial mutualists for their viability and reproduction [ 1 ]. These obligate associates, called 'primary' (P-) endosymbionts because they are required for host survival and fecundity, often synthesize key nutrients that are lacking in the hosts' unbalanced diet ( e.g ., plant sap or vertebrate blood) [ 2 - 4 ]. In all cases, the bacteria live within specialized host cells called bacteriocytes and undergo maternal transmission to developing eggs or embryos.…”

Attacins: A Promising Class of Insect Antimicrobial Peptides

“…Having colonized nearly every ecological niche, insects can be considered the most successful animal taxon on Earth [ 46 , 47 ]. Their large AMP repertoire may be reasonably related to various environmental threats faced by each species during evolution [ 48 ].…”