Bacillus cereusgroup species are widespread, Gram-positive, spore-forming environmental bacteria.B. cereus sensu strictois one of the major causes of food poisoning worldwide. In high-risk individuals, such as preterm neonates,B. cereusinfections can cause fatal infections. It is important to note that the phenotypic identification methods commonly used in clinical microbiology laboratories make no distinction betweenB. cereus sensu strictoand the other members of the group (Bacillus anthracisexcluded).

MALDI-TOF Mass Spectrometry is not widely used to identify bacteria directly from positive blood culture bottles (BCBs) because of overlong protocols. The objective of this work was to develop and evaluate a simple extraction protocol for reliable identification from BCBs. The 10-minute protocol was applied over a five-month period. Direct identifications on Day0 were compared with those obtained from colonies on Day1 (log(score) ≥ 2). We evaluated a range of seven log(score) thresholds on Day0 from 1.4 to 2.0 to find the lower confidence score that provides the higher percentage of direct identifications without loss of accuracy. With a log(score) threshold ≥ 1.5 at Day0, our protocol allowed us to identify 80% of bacteria in 632 BCBs (96% of Enterobacteriaceae, 95% of Staphylococcus aureus, 92% of enterococci and 62% of streptococci). At least one bacterial species of the mixture was identified in 77% of the polymicrobial samples. The rapidity and reliability of the protocol were factors in its adoption for routine use, allowing us to save up to 24 hours in identifying 80% of the bacteria in the BCBs and thus to supply useful information to adapt antibiotic therapy when necessary. We currently provide reliable daily direct identifications of staphylococci, enterococci, Enterobacteriaceae, Pseudomonas aeruginosa and beta-hemolytic streptococci.

Pandoraea spp. are recently discovered bacteria, mainly recovered from cystic fibrosis (CF) patients, but their epidemiology and clinical significance are not well known. We describe an epidemic spread of Pandoraea pulmonicola from 2009 in our CF center, involving 6 out of 243 CF patients. Bacterial identification used amplified ribosomal DNA restriction analysis (ARDRA), MALDI-TOF mass spectrometry (MALDI-TOF MS) and 16S rDNA gene sequencing. The clonal link between strains was assessed with pulsed field gel electrophoresis (PFGE) using XbaI. Clinical data were gathered for all patients. The index case was chronically colonized since 2000. The main hypothesis for this bacterial spread was a droplet cross-transmission, due to preventive measures not being strictly followed. Antibiotic susceptibility testing revealed resistance to beta-lactams, ciprofloxacin and colistin. However, there was susceptibility to trimethoprim-sulfamethoxazole. All patients were chronically colonized with Pseudomonas aeruginosa, and the acquisition of P. pulmonicola resulted in chronic colonization in all patients. Three patients died, and two patients remained clinically stable, whereas one patient had a decline in lung function. This study, which is the first to describe an epidemic spread of P. pulmonicola, notes the potential transmissibility of this bacterial species and the need for infection control measures.

The E3 ubiquitin ligase HACE1 is a potent tumor suppressor that controls cell proliferation and ubiquitylates the small GTPase Rac1 to target it to proteasomal degradation. Whether and how the activity of HACE1 is regulated by the N-terminal ankyrin (ANK) and the middle (MID) domains is ill defined. Here, we identified in the version 64 of the Catalogue of Somatic Mutations in Cancer (COSMIC) 13 missense mutations of hace1 located outside the HECT domain, and found that all lead to defective control of cell proliferation. In addition, several mutations located in the ankyrin domain displayed a dramatic reduction in Rac1 ubiquitylation associated with a decrease of colony formation in soft agar. 3D structure modelling of the 7 ankyrin-repeats coupled to functional analysis identified a surface epitope centered on one of the mutated residue, Gly-175, which is critical for controlling Rac1 binding and ubiquitylation. We also identified a role for the MID domain in conferring the specificity of association of HACE1 to the active form of Rac1. Our study of the functional interplay between HACE1 and Rac1 in cancer thus sheds a new light on the molecular mechanism of Rac1 ubiquitylation by HACE1 and the impact of its cancer-associated mutations in cell proliferation.