A new culture-based method for rapid identification of microorganisms in polymicrobial blood cultures by MALDI-TOF MS

Florio, Walter; Cappellini, Susanna; Giordano, Cesira; Vecchione, Alessandra; Ghelardi, Emilia; Lupetti, Antonella

doi:10.1186/s12866-019-1641-1

Cited by 29 publications

(16 citation statements)

References 37 publications

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“…The results of this study were consistent with that of other recent studies denoting the efficacy and efficiency of MALDI-TOF MS for the identification of Gram-negative bacteria [ 13 , 33 , 34 ]. Moreover, this study indicated that a replacement for the traditional identification method for R. ornithinolytica isolation in the microbiology laboratory was important.…”

Section: Discussionsupporting

confidence: 92%

Emergence of Raoultella ornithinolytica isolated from chicken products in Alexandria, Egypt

El-Shannat¹,

Tawab

Hassan³

2020

Vet World

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Background and Aim: Raoultella ornithinolytica is one of the emerging gram-negative bacteria, which associated with foodborne illness. Researches affirmed that distinguish between R. ornithinolytica and Klebsiella oxytoca are difficult, as they are phylogenetic related. The evolution of multidrug resistance of Raoultella strains gained more concern for recognition of the pathogen which supports in controlling the disease and minify its threat. This study sought to find a reliable tool for the identification of Raoultella ornithinolytica, isolated from chicken product samples, and assessed the resistance profile of R. ornithinolytica using antibiogram sensitivity tests. Materials and Methods: Forty samples of chicken products were collected between January and September 2019 from different markets in Alexandria Governorate, Egypt. The products included nuggets, strips, burgers, luncheon meats, pane, frankfurters, and minced chicken meat. The samples were transferred to the Reference Laboratory. The samples were subjected to isolation, biochemical reaction testing, phenotypic system analytical profile index (API) E20, and a detection of antimicrobial susceptibility test. Phenotypic identification was confirmed through matrix-assisted laser-desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Results: Thirty-three bacterial isolates (82.50%) out of 40 samples were isolated into pure cultures from the chicken samples. Three isolates (9.09%) were positive for R. ornithinolytica, while 30 isolates (90.91%) exhibited growth characters for different pathogens (Escherichia coli, Enterobacter aerogenes, Proteus vulgaris, R. ornithinolytica, and Klebsiella pneumoniae). The isolates of R. ornithinolytica were resistant to five types of antibiotics and sensitive to two types of antibiotics. Conclusion: This study reported the first case of R. ornithinolytica found in chicken products in Egypt. Phenotypic system API 20E and MALDI-TOF MS were found to be reliable tools for confirming the diagnosis of R. ornithinolytica. As it provides rapid identification with high sensitivity and specificity for R. ornithinolytica, which often do not require a molecular procedure for confirmation.

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Section: Discussionsupporting

confidence: 92%

Emergence of Raoultella ornithinolytica isolated from chicken products in Alexandria, Egypt

El-Shannat¹,

Tawab

Hassan³

2020

Vet World

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“…Our results indicated that the M1 method, which eliminated the incubation of blood samples in liquid medium, saved approximately 35 to 43 h compared to the time required for the standard blood culture method. Though MALDI-TOF MS identification directly with positive blood culture has been used more widely in recent years, it is still difficult to analyze positive blood culture with polymicrobial infection (36). Therefore, in this retrospective study, the standard blood culture method still included the time for individual colony formation.…”

Section: Discussionmentioning

confidence: 99%

Direct Blood Culturing of Candida spp. on Solid Medium by a Rapid Enrichment Method with Magnetic Beads Coated with Recombinant Human Mannan-Binding Lectin

Chen

Zheng

et al. 2020

J Clin Microbiol

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A rapid and accurate method to identify the species and antibiotic resistance of Candida spp. in blood is vital to increase the survival rates of patients with bloodstream infections. However, the extremely low levels of Candida spp. in blood make rapid diagnosis by standard blood culture difficult. In this study, we constructed a direct blood culturing method (i.e., the M1 method) by a rapid enrichment method with magnetic beads coated with a recombined human mannan-binding lectin (rhMBL; i.e., M1 protein), which demonstrated much higher Candida sp.-binding capacity than that of full-length MBL expressed in vitro (i.e., M2). With the M1 method, individual colonies were obtained before the standard blood culture method for each species of Candida spp. tested at <1 CFU/ml (an average of 29 h earlier). Additionally, the clinical sensitivity of the M1 method was 90.5% compared with that of the standard blood culture method when detecting frozen plasma from patients. More significantly, the turnaround time of the M1 method for blood culture could be reduced by approximately 37 to 43 h compared with that of the standard blood culture method in clinical sample identification.

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“…The short incubation method has been used for polymicrobial cases as well. Although there is a report indicating that both microorganisms present in 43 (86%) of 50 polymicrobial blood culture bottles were correctly identified after short-term culture [60], it is a general view that short incubation method is not successfully applicable to polymicrobial blood stream infections [19].…”

Section: Id Of Polymicrobial Cultures With Maldi-tof Msmentioning

confidence: 97%

Mass spectrometry-based microbiological testing for blood stream infection

et al. 2020

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Background: The most successful application of mass spectrometry (MS) in laboratory medicine is identification (ID) of microorganisms using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) in blood stream infection. We describe MALDI-TOF MS-based bacterial ID with particular emphasis on the methods so far developed to directly identify microorganisms from positive blood culture bottles with MALDI-TOF MS including our own protocols. We touch upon the increasing roles of Liquid chromatography (LC) coupled with tandem mass spectrometry (MS/MS) as well. Main body: Because blood culture bottles contain a variety of nonbacterial proteins that may interfere with analysis and interpretation, appropriate pretreatments are prerequisites for successful ID. Pretreatments include purification of bacterial pellets and short-term subcultures to form microcolonies prior to MALDI-TOF MS analysis. Three commercial protocols are currently available: the Sepsityper ® kit (Bruker Daltonics), the Vitek MS blood culture kit (bioMerieux, Inc.), and the rapid BACpro ® II kit (Nittobo Medical Co., Tokyo). Because these commercially available kits are costly and bacterial ID rates using these kits are not satisfactory, particularly for Gram-positive bacteria, various home-brew protocols have been developed: 1. Stepwise differential sedimentation of blood cells and microorganisms, 2. Combination of centrifugation and lysis procedures, 3. Lysis-vacuum filtration, and 4. Centrifugation and membrane filtration technique (CMFT). We prospectively evaluated the performance of this CMFT protocol compared with that of Sepsityper ® using 170 monomicrobial positive blood cultures. Although preliminary, the performance of the CMFT was significantly better than that of Sepsityper ® , particularly for Gram-positive isolates. MALDI-TOF MS-based testing of polymicrobial blood specimens, however, is still challenging. Also, its contribution to assessment of susceptibility and resistance to antibiotics is still limited. For this purpose, liquid chromatography (LC) coupled with tandem mass spectrometry (MS/MS) should be more useful because this approach can identify as many as several thousand peptide sequences. Conclusion: MALDI-TOF MS is now an essential tool for rapid bacterial ID of pathogens that cause blood stream infection. For the purpose of assessment of susceptibility and resistance to antibiotics of the pathogens, the roles of liquid chromatography (LC) coupled with tandem mass spectrometry (MS/MS) will increase in the future.

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A new culture-based method for rapid identification of microorganisms in polymicrobial blood cultures by MALDI-TOF MS

Cited by 29 publications

References 37 publications

Emergence of Raoultella ornithinolytica isolated from chicken products in Alexandria, Egypt

Emergence of Raoultella ornithinolytica isolated from chicken products in Alexandria, Egypt

Direct Blood Culturing of Candida spp. on Solid Medium by a Rapid Enrichment Method with Magnetic Beads Coated with Recombinant Human Mannan-Binding Lectin

Mass spectrometry-based microbiological testing for blood stream infection

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