Evaluation of QuickFISH and maldi Sepsityper for identification of bacteria in bloodstream infection

Abstract

Background: Early detection of bacteria and their antibiotic susceptibility patterns are critical to guide therapeutic decision-making for optimal care of septic patients. The current gold standard, blood culturing followed by subculture on agar plates for subsequent identification, is too slow leading to excessive use of broad-spectrum antibiotic with harmful consequences for the patient and, in the long run, the public health. The aim of the present study was to assess the performance of two commercial assays, QuickFISHV R (OpGen) and Maldi Sepsityper TM (Bruker Daltonics) for early and accurate identification of microorganisms directly from positive blood cultures. Materials and methods: During two substudies of positive blood cultures, the two commercial assays were assessed against the routine method used at the clinical microbiology laboratory, Unilabs AB, at Skaraborg Hospital, Sweden. Results: The Maldi Sepsityper TM assay enabled earlier microorganism identification. Using the cutoff for definite species identification according to the reference method (>2.0), sufficiently accurate species identification was achieved, but only among Gram-negative bacteria. The QuickFISH V R assay was time-saving and showed high concordance with the reference method, 94.8% (95% CI 88.4-98.3), when the causative agent was covered by the QuickFISH V R assay. Conclusions: The use of the commercial assays may shorten the time to identification of causative agents in bloodstream infections and can be a good complement to the current clinical routine diagnostics. Nevertheless, the performance of the commercial assays is considerably affected by the characteristics of the causative agents.

Evaluation of Rapid Sepsityper® protocol and specific MBT-Sepsityper module (Bruker Daltonics) for the rapid diagnosis of bacteremia and fungemia by MALDI-TOF-MS

“…Formic acid use was mandatory to increase identification rate of GP bacteria which otherwise dropped from 20% between RS + FA and RS protocols but remained lower than for GN bacteria, as already experienced in other studies [30,35]. It may be explained by the adherence of GP bacteria to the red blood cells and their removal with the serum (P. Murray, Becton Dickinson, personal communication), by a more robust cell wall which decreases protein extraction yields or by a smaller pellet after extraction due to a slower growth or lower biomass of GP bacteria in positive blood cultures [30,52].…”

“…While blood culture remains the reference method for BSI diagnosis, new rapid methods have emerged to reduce the delay to identify bacterial and fungal pathogens. They may be realized directly from whole blood (multiplex PCR; T2 magnetic resonance) [61][62][63][64][65] but are mainly performed on positive blood culture bottles using either MALDI-TOF-MS-based techniques (direct identification after purification of bacterial or fungal pellets; identification after short-term incubation on a solid medium) [30][31][32][33]45] or molecular-based techniques (multiplex-PCR, PNA-FISH) [31,[35][36][37]39].…”

“…In particular, despite their low cost, the important handson-time of MALDI-TOF-MS assays still prevents many laboratories to perform rapid identification on positive blood cultures, which results in a loss of opportunity for the patients. In-house and commercial protocols such as the Sepsityper ® kit (Bruker Daltonics GmbH, Bremen, Germany) usually take between 20 to 40 min of turnaround time [22,28,[30][31][32][33][34][35][36][37][38][39][40][41][42][43]. A comprehensive overview of current performances and estimated hands-on time of the different rapid identification methods using MALDI-TOF-MS on positive blood cultures has been gathered in Table 1.…”

Genotypic Characterization of Clinical Klebsiella spp. Isolates Collected From Patients With Suspected Community-Onset Sepsis, Sweden

“…Species identification of isolates was performed with MALDI-TOF MS in the clinical laboratory Unilabs at Skaraborg Hospital on a MicroFlex LT mass spectrometer (Bruker Daltonics, Germany) with BioTyper software v2.0 using default parameter settings as part of the routine clinical practice as described elsewhere (Ljungstrom et al, 2015;Enroth et al, 2019). Spectral scores above 2.0 were used as cut-off for correct identification.…”

Modern Tools for Rapid Diagnostics of Antimicrobial Resistance

“…The PNA-FISH technology applies peptide nucleic acid probes which allow more rapid and specific binding than DNA or RNA probes (Perry-O'Keefe et al, 2001 ; Almeida et al, 2009 ; Cerqueira et al, 2011 ). It is applied in the commercial QuickFish technology (OpGen, USA) which performs ID by targeting 16S rRNA (Enroth et al, 2019 ). XpressFish specifically detects the mecA gene in Staphylococcus , allowing, when used subsequent to QuickFish-based identification, diagnosis of methicillin resistance already 2 h after the blood culture turns positive (Salimnia et al, 2014 ).…”