Multicenter evaluation of the VITEK MS matrix-assisted laser desorption/ionization-time of flight mass spectrometry system for identification of bacteria, including Brucella, and yeasts.

The use of matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry has proven to be rapid and accurate for the majority of clinical isolates. Some gaps remain concerning rare, emerging, or highly pathogenic species, showing the need to continuously expand the databases. In this multicenter study, we evaluated the accuracy of the VITEK MS v3.2 database in identifying 1172 unique isolates compared to identification by DNA sequence analysis. A total of 93.6% of the isolates were identified to species or group/complex level. A remaining 5.2% of the isolates were identified to the genus level. Forty tests gave a result of no identification (0.9%) and 12 tests (0.3%) gave a discordant identification compared to the reference identification. VITEK MS is also the first MALDI-TOF MS system that is able to delineate the four members of the Acinetobacter baumannii complex at species level without any specific protocol or special analysis method. These findings demonstrate that the VITEK MS v3.2 database is highly accurate for the identification of bacteria and fungi encountered in the clinical laboratory as well as emerging species like Candida auris and the highly pathogenic Brucella species.

Development and application of MALDI-TOF MS for identification of food spoilage fungi.

Filamentous fungi are frequently involved in food spoilage and cause important food losses and substantial economic damage. Their rapid and accurate identification is a key step to better manage food safety and quality. In recent years, MALDI-TOF MS has emerged as a powerful tool to identify microorganisms and has successfully been applied to the identification of filamentous fungi especially in the clinical context. The aim of this study was to implement a spectral database representative of food spoilage molds. To this end, after application of a standardized extraction protocol, 6477 spectra were acquired from 618 fungal strains belonging to 136 species and integrated in the VITEK MS database. The performances of this database were then evaluated by cross-validation and ∼95% of correct identification to the species level was achieved, independently of the cultivation medium and incubation time. The database was also challenged with external isolates belonging to 52 species claimed in the database and 90% were correctly identified to the species level. To our best knowledge, this is the most comprehensive database of food-relevant filamentous fungi developed to date. This study demonstrates that MALDI-TOF MS could be an alternative to conventional techniques for the rapid and reliable identification of spoilage fungi in food and industrial environments.

A MALDI-TOF MS database with broad genus coverage for species-level identification of Brucella.

Brucella are highly infectious bacterial pathogens responsible for a severely debilitating zoonosis called brucellosis. Half of the human population worldwide is considered to live at risk of exposure, mostly in the poorest rural areas of the world. Prompt diagnosis of brucellosis is essential to prevent complications and to control epidemiology outbreaks, but identification of Brucella isolates may be hampered by the lack of rapid and cost-effective methods. Nowadays, many clinical microbiology laboratories use Matrix-Assisted Laser Desorption Ionization-Time Of Flight mass spectrometry (MALDI-TOF MS) for routine identification. However, lack of reference spectra in the currently commercialized databases does not allow the identification of Brucella isolates. In this work, we constructed a Brucella MALDI-TOF MS reference database using VITEK MS. We generated 590 spectra from 84 different strains (including rare or atypical isolates) to cover this bacterial genus. We then applied a novel biomathematical approach to discriminate different species. This allowed accurate identification of Brucella isolates at the genus level with no misidentifications, in particular as the closely related and less pathogenic Ochrobactrum genus. The main zoonotic species (B. melitensis, B. abortus and B. suis) could also be identified at the species level with an accuracy of 100%, 92.9% and 100%, respectively. This MALDI-TOF reference database will be the first Brucella database validated for diagnostic and accessible to all VITEK MS users in routine. This will improve the diagnosis and control of brucellosis by allowing a rapid identification of these pathogens.

Limits of intravascular contrast extravasation on computed tomography scan to define the need for pelvic angioembolization in pelvic blunt trauma: a specific assessment on the risk of false positives.

BACKGROUND: The objective was to assess the predictive performance of different intravascular contrast extravasation (ICE) characteristics for need for pelvic transarterial embolization (TAE) to determine the risk factors of false positives. METHODS: A retrospective study was performed in our trauma center between 2010 and 2015. All severe trauma patients with pelvic fracture were included. Pelvic ICE characteristics on computed tomography (CT) scan were studied: arterial (aSICE), portal surface (pSICE), and extension (exSICE) anatomic relationships. The overall predictive performance of ICE surfaces for pelvic TAE was analyzed using receiver operating characteristic curves. The analysis focused on risk factors for false positives. RESULTS: Among 311 severe trauma patients with pelvic ring fracture (mean age, 42 ± 19 years; mean Injury Severity Score, 27 ± 19), 94 (30%) had at least one pelvic ICE on the initial CT scan. Patients requiring pelvic TAE had significantly larger aSICE and pSICE than others (p = 0.001 and p = 0.035, respectively). The overall ability of ICE surfaces to predict pelvic TAE was modest (aSICE area under the receiver operating characteristic curve, 0.76 [95% confidence interval, 0.64-0.90]; p = 0.011) or nonsignificant (pSICE and exSICE). The high-sensitivity threshold was defined as aSICE 20 mm or more. Using this threshold, 76% of patients were false positives. Risk factors for false positives were admission systolic blood pressure of 90 mm Hg or greater (63% vs 20%; p = 0.03) and low transfusion needs (63% vs 10%; p = 0.009), extravasation in contact with complex bone fracture (78% vs 30%; p = 0.008), or the absence of a direct relationship between extravasation and a large retroperitoneal hematoma (100% vs 38%; p < 0.001). CONCLUSION: A significant pelvic ICE during the arterial phase does not guarantee the need for pelvic TAE. Three quarters of patients with aSICE of 20 mm or more did not need pelvic TAE. Several complementary CT scan criteria will help to identify this risk of false positives to determine adequate hemostatic pelvic procedures. LEVEL OF EVIDENCE: Therapeutic study, level IV.

Renal graft intolerance syndrome in late graft failure patients: efficacy and safety of embolization as first-line treatment compared to surgical removal.

Although renal graft percutaneous embolization was introduced to avoid the risk associated with graft nephrectomy, there is no universal consensus about its indications and results. In order to evaluate the efficacy of graft embolization in the treatment of graft intolerance syndrome as well as its safety compared to surgical removal with respect to complications and other morbidity measures, We performed a retrospective observational study comparing two groups of patients treated for graft intolerance syndrome: Group 1: patients who had embolization as first-line treatment and Group 2: patients directly treated by surgical removal. 72 patients were included, (32 in Group 1 and 40 in Group 2); the postintervention follow-up continued for 12 months. Patients in Group 1 are older than those in Group 2. Otherwise, the two groups are similar concerning sex, manifestations of graft intolerance syndrome, diabetes and nutritional and functional status. The overall success rate of embolization in complete resolution of graft intolerance syndrome and ultimately avoidance of surgical removal was 84.37%. The surgical removal group had more serious complications, a longer hospital stay and needed more blood transfusions. We conclude that embolization of symptomatic renal grafts has considerable efficacy with less morbidity, and no serious complications compared to the standard surgical graft removal.

Routine identification of Nocardia species by MALDI-TOF mass spectrometry.

We here show adequate species identification for bacterial isolates of the genus Nocardia spp. through VITEK mass spectrometry. Application of a specific sample preparation method in combination with a robust matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) database leads to 94% accurate identification to the species level on a set of 164 isolates. The possibility to identify Nocardia spp. using MALDI-TOF MS will be available in the next release of VITEK MS update (IVD Version 3.0).

A Simple and Safe Protocol for Preparing Brucella Samples for Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry Analysis.

We describe a simple protocol to inactivate the biosafety level 3 (BSL3) pathogens Brucella prior to their analysis by matrix-assisted laser desorption ionization-time of flight mass spectrometry. This method is also effective for several other bacterial pathogens and allows storage, and eventually shipping, of inactivated samples; therefore, it might be routinely applied to unidentified bacteria, for the safety of laboratory workers.

Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry using the Vitek MS system for rapid and accurate identification of dermatophytes on solid cultures.

The objective of this research was to extend the Vitek MS fungal knowledge base version 2.0.0 to allow the robust identification of clinically relevant dermatophytes, using a variety of strains, incubation times, and growth conditions. First, we established a quick and reliable method for sample preparation to obtain a reliable and reproducible identification independently of the growth conditions. The Vitek MS V2.0.0 fungal knowledge base was then expanded using 134 well-characterized strains belonging to 17 species in the genera Epidermophyton, Microsporum, and Trichophyton. Cluster analysis based on mass spectrum similarity indicated good species discrimination independently of the culture conditions. We achieved a good separation of the subpopulations of the Trichophyton anamorph of Arthroderma benhamiae and of anthropophilic and zoophilic strains of Trichophyton interdigitale. Overall, the 1,130 mass spectra obtained for dermatophytes gave an estimated identification performance of 98.4%. The expanded fungal knowledge base was then validated using 131 clinical isolates of dermatophytes belonging to 13 taxa. For 8 taxa all strains were correctly identified, and for 3 the rate of successful identification was >90%; 75% (6/8) of the M. gypseum strains were correctly identified, whereas only 47% (18/38) of the African T. rubrum population (also called T. soudanense) were recognized accurately, with a large quantity of strains misidentified as T. violaceum, demonstrating the close relationship of these two taxa. The method of sample preparation was fast and efficient and the expanded Vitek MS fungal knowledge base reliable and robust, allowing reproducible dermatophyte identifications in the routine laboratory.

Automatic identification of mixed bacterial species fingerprints in a MALDI-TOF mass-spectrum.

MOTIVATION: Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry has been broadly adopted by routine clinical microbiology laboratories for bacterial species identification. An isolated colony of the targeted microorganism is the single prerequisite. Currently, MS-based microbial identification directly from clinical specimens can not be routinely performed, as it raises two main challenges: (i) the nature of the sample itself may increase the level of technical variability and bring heterogeneity with respect to the reference database and (ii) the possibility of encountering polymicrobial samples that will yield a 'mixed' MS fingerprint. In this article, we introduce a new method to infer the composition of polymicrobial samples on the basis of a single mass spectrum. Our approach relies on a penalized non-negative linear regression framework making use of species-specific prototypes, which can be derived directly from the routine reference database of pure spectra. RESULTS: A large spectral dataset obtained from in vitro mono- and bi-microbial samples allowed us to evaluate the performance of the method in a comprehensive way. Provided that the reference matrix-assisted laser desorption/ionization time-of-flight mass spectrometry fingerprints were sufficiently distinct for the individual species, the method automatically predicted which bacterial species were present in the sample. Only few samples (5.3%) were misidentified, and bi-microbial samples were correctly identified in up to 61.2% of the cases. This method could be used in routine clinical microbiology practice.

Hepatic arterial embolization in the management of blunt hepatic trauma: indications and complications.

BACKGROUND: The objective was to clarify the role of hepatic arterial embolization (AE) in the management of blunt hepatic trauma. METHODS: Retrospective observational study of 183 patients with blunt hepatic trauma admitted to a trauma referral center over a 9-year period. The charts of 29 patients (16%) who underwent hepatic angiography were reviewed for demographics, injury specific data, management strategy, angiographic indication, efficacy and complications of embolization, and outcome. RESULTS: AE was performed in 23 (79%) of the patients requiring angiography. Thirteen patients managed conservatively underwent emergency embolization after preliminary computed tomography scan. Six had postoperative embolization after damage control laparotomy and four had delayed embolization. Arterial bleeding was controlled in all the cases. Sixteen patients (70%) had one or more liver-related complications; temporary biliary leak (n=11), intra-abdominal hypertension (n=14), inflammatory peritonitis (n=3), hepatic necrosis (n=3), gallbladder infarction (n=2), and compressive subcapsular hematoma (n=1). Unrecognized hepatic necrosis could have contributed to the late posttraumatic death of one patient. CONCLUSION: AE is a key element in modern management of high-grade liver injuries. Two principal indications exist in the acute postinjury phase: primary hemostatic control in hemodynamically stable or stabilized patients with radiologic computed tomography evidence of active arterial bleeding and adjunctive hemostatic control in patients with uncontrolled suspected arterial bleeding despite emergency laparotomy. Successful management of injuries of grade III upward often entails a combined angiographic and surgical approach. Awareness of the ischemic complications due to angioembolization is important.

Place of arterial embolization in severe blunt hepatic trauma: a multidisciplinary approach.

This study evaluates the efficacy of arterial embolization (AE) for blunt hepatic traumas (BHT) as part of a combined management strategy based on the hemodynamic status of patients and CT findings. From 2000 to 2005, 84 patients were admitted to our hospital for BHT. Of these, 14 patients who had high-grade injuries (grade III [n = 2], grade IV [n = 9], grade V [n = 3]) underwent AE because of arterial bleeding and were included in the study. They were classified into three groups according to their hemodynamic status: (1) unresponsive shock, (2) shock improved with resuscitation, and (3) hemodynamic stability. Four patients (group 1) underwent, first, laparotomy with packing and, then, AE for persistent bleeding. Ten patients who were hemodynamically stable (group 1) or even unstable (group 2) underwent AE first, based on CT findings. AE was successful in all cases. The mortality rate was 7% (1/14). Only two angiography-related complications (gallbladder infarction) were reported. Liver-related complications (abdominal compartment syndrome and biliary complications) were frequent and often required secondary interventions. Our multidisciplinary approach for the management of BHT gives a main role to embolization, even for hemodynamically unstable patients. In this strategy AE is very efficient and has a low complication rate.