Comparison of Real-Time Aspergillus PCR with Platelia™AspergillusEIA in broncho-alveolar lavage fluids for the diagnosis of invasive aspergillosis in neutropenic and non-neutropenic patients

Poster (2013, April 27)

Objectives. Because of low sensitivity of fungal cultures and lack of standardization of Aspergillus PCR, laboratory diagnosis of invasive aspergillosis still relies on galactomannan (GM) detection in ... [more ▼]

Objectives. Because of low sensitivity of fungal cultures and lack of standardization of Aspergillus PCR, laboratory diagnosis of invasive aspergillosis still relies on galactomannan (GM) detection in broncho-alveolar lavage (BAL) fluids and serum. The aim of this study was double: first, to assess the place of a 18S rRNA Aspergillus real-time PCR test performed in BAL fluid for the diagnosis of invasive aspergillosis (IA) in neutro- and non-neutropenic patients in comparison with GM detection; secondly, to evaluate the use of three different GM cut-off values. Materials and methods. A total of 111 neutropenic and non-neutropenic patients hospitalized at the University hospital of Liège from March to October 2012 with suspicion of IA were included in the study. A total of 138 broncho-alveolar lavage fluids were evaluated by three laboratory diagnostic methods: 1/ culture on Sabouraud agar slants with antibiotics (bioMérieux, France) incubated at 28°C for 28 days; 2/ GM detection (Platelia ™Aspergillus EIA, Biorad) using GM index cut-off values at 0.5, 0.8 and 1, performed three times a week; 3/ a real-time Aspergillus PCR assay performed daily and targeting the 18S rRNA genes by using an in-house method. Clinical, radiological and microbiological data were reviewed for classification of patients. Results. Nine patients developed probable or possible IA. The sensitivity/specificity/positive (VPP) and negative (NPV) predictive values (%) for culture, PCR, and GM using 0,5 as cut-off value were respectively 41/100/100/94, 58/97/70/96, and 91/83/34/99. The use of 0,8 and 1 as GM index cut-off values increased the specificity to 89 and 92% respectively, and the VPP to 44 and 54%. PCR had a better turn-around time and allowed the detection of Aspergillus colonisation. Conclusion: GM detection in BAL fluids using a cut-off value of 1 was the most efficient laboratory test for the diagnosis of IA in neutropenic and non-neutropenic patients. Despite a lower sensitivity, PCR had a better VPP, and allowed the detection of culture-negative Aspergillus colonisations. A shorter turnaround time (TAT) due to daily practice of PCR tests may reduce the time-to-treatment up to 24 hours. [less ▲]

Direct identification of bacteria from BacT/ALERT anaerobic positive blood cultures by MALDI-TOF MS: MALDI Sepsityper kit versus an in-house saponin method for bacterial extraction.

in Journal of Medical Microbiology (2012), 61

In cases of bacteraemia, a rapid species identification of the causal agent directly from positive blood culture broths could assist clinicians in the timely targeting of empirical antimicrobial therapy ... [more ▼]

In cases of bacteraemia, a rapid species identification of the causal agent directly from positive blood culture broths could assist clinicians in the timely targeting of empirical antimicrobial therapy. For this purpose, we evaluated the direct identification of micro-organisms from BacT/ALERT (bioMérieux) anaerobic positive blood cultures without charcoal using the Microflex matrix-assisted laser desorption/ionization (MALDI) time of flight MS (Bruker), after bacterial extraction by using two different methods: the MALDI Sepsityper kit (Bruker) and an in-house saponin lysis method. Bruker's recommended criteria for identification were expanded in this study, with acceptance of the species identification when the first three results with the best matches with the MALDI Biotyper database were identical, whatever the scores were. In total, 107 monobacterial cultures and six polymicrobial cultures from 77 different patients were included in this study. Among monomicrobial cultures, we identified up to the species level 67 and 66 % of bacteria with the MALDI Sepsityper kit and the saponin method, respectively. There was no significant difference between the two extraction methods. The direct species identification was particularly inconclusive for Gram-positive bacteria, as only 58 and 52 % of them were identified to the species level with the MALDI Sepsityper kit and the saponin method, respectively. Results for Gram-negative bacilli were better, with 82.5 and 90 % of correct identification to the species level with the MALDI Sepsityper kit and the saponin method, respectively. No misidentifications were given by the direct procedures when compared with identifications provided by the conventional method. Concerning the six polymicrobial blood cultures, whatever the extraction method used, a correct direct identification was only provided for one of the isolated bacteria on solid medium in all cases. The analysis of the time-to-result demonstrated a reduction in the turnaround time for identification ranging from 1 h 06 min to 24 h 44 min, when performing the blood culture direct identification in comparison with the conventional method, whatever the extraction method. [less ▲]

Acute cholecystitis with Listeria monocytogenes

in Acta Clinica Belgica (2012), 67(4), 295-297

Listeriosis, an opportunistic food-borne disease caused by Listeria monocytogenes, is infrequent and occurs preferentially in patients at the extremes of age, during pregnancy or in immunocompromised ... [more ▼]

Listeriosis, an opportunistic food-borne disease caused by Listeria monocytogenes, is infrequent and occurs preferentially in patients at the extremes of age, during pregnancy or in immunocompromised hosts. Most common manifestations are maternofoetal and neonatal infections, severe invasive presentations such as bacteraemia with or without central nervous system symptoms occuring preferentially in immunosuppressed patients and self-limited gastro-enteritis affecting healthy individuals. Exceptionally, focal infections such as cholecystitis are described. We report here a case of acute cholecystitis caused by Listeria monocytogenes in an 82-year-old woman. Thanks to a successful treatment: cholecystectomy and antimicrobial therapy (amoxicillin plus clavulanic acid), the patient soon recovered. This case-report provides an opportunity to review the current literature concerning the association of Listeria monocytogenes and cholecystitis. [less ▲]

Critical difference: from results to interpretation and its impact on patient care

Poster (2008, May)