Evaluation of Three Rapid Diagnostic Methods for Direct Identification of Microorganisms in Positive Blood Cultures

Martínez, Raquel; Bauerle, Elizabeth; Fang, Ferric C.; Butler-Wu, Susan M.

doi:10.1128/jcm.00529-14

Cited by 92 publications

(69 citation statements)

References 49 publications

(75 reference statements)

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“…The incorporation of this methodology in clinical laboratories has been an important improvement in the etiologic diagnosis of all types of infections, as its speed and relatively low cost have displaced the classical biochemical identification. Previous studies have evaluated the ability of MALDI-TOF MS to identify microorganisms in positive blood cultures (10,(15)(16)(17)(18)(19). The next step was the identification of microorganisms from direct samples, without prior culture.…”

Section: Discussionmentioning

confidence: 99%

Direct Identification of Urinary Tract Pathogens from Urine Samples, Combining Urine Screening Methods and Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

et al. 2016

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Early diagnosis of urinary tract infections (UTIs) is essential to avoid inadequate or unnecessary empirical antibiotic therapy. Microbiological confirmation takes 24 to 48 h. The use of screening methods, such as cytometry and automated microscopic analysis of urine sediment, allows the rapid prediction of negative samples. In addition, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is a widely established technique in clinical microbiology laboratories used to identify microorganisms. We evaluated the ability of MALDI-TOF MS to identify microorganisms from direct urine samples and the predictive value of automated analyzers for the identification of microorganisms in urine by MALDI-TOF MS. A total of 451 urine samples from patients with suspected UTIs were first analyzed using the Sysmex UF-1000i flow cytometer, an automatic sediment analyzer with microscopy (SediMax), culture, and then processed by MALDI-TOF MS with a simple triplecentrifuged procedure to obtain a pellet that was washed and centrifuged and finally applied directly to the MALDI-TOF MS plate. The organisms in 336 samples were correctly identified, mainly those with Gram-negative bacteria (86.10%). No microorganisms were misidentified, and no Candida spp. were correctly identified. Regarding the data from autoanalyzers, the best bacteriuria cutoffs were 1,000 and 200 U/l for UF-1000i and SediMax, respectively. It was concluded that the combination of a urine screening method and MALDI-TOF MS provided a reliable identification from urine samples, especially in those containing Gram-negative bacteria. U rinary tract infections (UTIs) are among the most common nosocomial and community-acquired bacterial infections (1). The etiology is varied, but in approximately 90% of cases, enteric bacteria are implicated, especially Escherichia coli, which produces Ͼ70% of these infections. Other urinary tract pathogens are Klebsiella spp., Enterobacter spp., Proteus spp., Pseudomonas spp., Enterococcus spp., and Staphylococcus saprophyticus (2).A rapid diagnosis of UTIs has a significant beneficial impact on patient health, since it reduces unnecessary or inadequate empirical antimicrobial therapy (3). Urine culture is still the gold standard for the microbiological confirmation of UTIs; however, it takes 24 to 48 h to provide results. The use of screening methods, such as traditional Gram staining or other methods for counting urine particles, like flow cytometry or automated microscopic urine sediment analysis, allow the prompt prediction of negative samples and a preliminary identification of microorganisms in positive samples (4-7). Nevertheless, this information obtained from these methods is insufficient and requires culture and other biochemical tests.In recent years, proteomic techniques have achieved a relevant role in the identification of microorganisms in the field of clinical microbiology. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has been suggested as a...

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Section: Discussionmentioning

confidence: 99%

Direct Identification of Urinary Tract Pathogens from Urine Samples, Combining Urine Screening Methods and Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

et al. 2016

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“…Our method was able to identify at least one organism present in all three polymicrobial specimens without any incorrect identifications. Other molecular methods for rapidly identifying organisms present in positive blood cultures have all been limited in their ability to detect all of the organisms present in polymicrobial specimens (13).…”

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confidence: 99%

Rapid Identification of Positive Blood Cultures by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry Using Prewarmed Agar Plates

et al. 2014

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bThis study describes an inexpensive and straightforward method for identifying bacteria by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) directly from positive blood cultures using prewarmed agar plates. Different inoculation methods and incubation times were evaluated to determine the optimal conditions. The two methods using pelleted material from positive culture bottles performed best. In particular, the pellet streak method correctly identified 94% of the Gram negatives following 4 h of incubation and 98% of the Gram positives following 6 h of incubation.

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“…The identification of microorganisms from bottles with polymicrobial growth is demanding for both conventional and rapid identification methods (12,14,16). Certain specimens in this study demonstrated that conventional identification methods may initially fail to identify microorganisms in bottles with polymicrobial growth.…”

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confidence: 98%

“…However, the identification of microorganisms from positive bottles with conventional methods may still take up to 48 h for many microorganisms and even longer for others, such as slow-growing bacteria and yeasts (11). Several methods have been evaluated for rapid identification of microorganisms directly from positive blood cultures (12)(13)(14). In contrast, the data on the performance of rapid microbiological methods in diagnostics of SBF are scarce.…”

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confidence: 99%

“…However, Micrococcus species, Corynebacterium species, and Bacillus cereus are usually considered contaminants, as they are part of normal skin microbiota, while Actinomyces species and Aeromonas species may be clinically significant findings in certain patient populations. This is a common limitation with similar rapid methods that are directed toward identifying the most common clinically significant microorganisms (12,14,15).…”

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Rapid Identification of Microorganisms from Sterile Body Fluids by Use of FilmArray

et al. 2015

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Early detection and rapid identification of microorganisms are crucial the for appropriate management of infections of normally sterile body fluids (SBF) (1-3). Previously, SBF other than blood were cultured on solid medium (4). Larger volumes were processed through centrifugation and filtration in order to concentrate and improve the detection of microorganisms. Nonetheless, the microorganism recovery from SBF was unsatisfactory until the introduction of blood culture (BC) bottles. The introduction of BC bottles resulted in increased microorganism recovery in addition to decreased time to detection (5-10). However, the identification of microorganisms from positive bottles with conventional methods may still take up to 48 h for many microorganisms and even longer for others, such as slow-growing bacteria and yeasts (11). Several methods have been evaluated for rapid identification of microorganisms directly from positive blood cultures (12)(13)(14). In contrast, the data on the performance of rapid microbiological methods in diagnostics of SBF are scarce. The aim of the present study was to evaluate the performance of the FilmArray blood culture identification (BCID) panel in the identification of microorganisms directly from positive blood culture bottles inoculated with clinical SBF specimens.This study was performed at Karolinska University Hospital, Huddinge, Sweden. SBF specimens were collected in the clinical wards using standard protocols. Specimen volumes of 1 to 2 ml were inoculated in BacT/Alert pediatric/PF plus (bioMérieux, Durham, NC, USA), and volumes of Ͼ2 ml in BacT/Alert aerobic/FA plus and anaerobic/FN plus bottles (bioMérieux). All bottles were incubated in the BacT/Alert 3D blood culture system (bioMérieux) until they gave a positive signal or for a maximum incubation time of 5 days.Positive BC bottles with SBF were processed as follows. Gram staining was performed immediately after bottles signaled positivity. All positive bottles were subcultured onto a Columbia blood agar plate (aerobic and anaerobic), a cystinelactose-electrolyte-deficient plate (CLED) agar, and a chocolate agar plate. After an incubation time of 48 h, we analyzed the growth morphology on the agar plates. Identification of microorganisms was done by conventional methods, including matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS; Bruker Daltonics, Bremen, Germany) and Vitek2 XL (bioMérieux). Susceptibility testing was performed by the disc diffusion method according to EUCAST guidelines (http://www.eucast.org/). Methicillin resistance in Staphylococcus spp. was evaluated by the cefoxitin disc diffusion method. Similarly, imipenem and meropenem disc diffusion methods were used in order to determine/confirm the absence of Klebsiella pneumoniae carbapenemase (KPC). FilmArray (FA; bioFire, Salt Lake City, UT) analyses were performed as previously described (13). Results that were discrepant between the reference method and the FilmArray were evaluated further. According to the discre...

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Evaluation of Three Rapid Diagnostic Methods for Direct Identification of Microorganisms in Positive Blood Cultures

Cited by 92 publications

References 49 publications

Direct Identification of Urinary Tract Pathogens from Urine Samples, Combining Urine Screening Methods and Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

Direct Identification of Urinary Tract Pathogens from Urine Samples, Combining Urine Screening Methods and Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

Rapid Identification of Positive Blood Cultures by Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry Using Prewarmed Agar Plates

Rapid Identification of Microorganisms from Sterile Body Fluids by Use of FilmArray

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