The impact of delayed analysis of positive blood cultures on the performance of short-term culture followed by MALDI-TOF MS

Johnsson, Alexander T A; Wong, Alicia Yoke Wei; Özenci, Volkan

doi:10.1016/j.mimet.2020.106027

Cited by 6 publications

(4 citation statements)

References 15 publications

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“… 6 Therefore, other methods that can be used in most laboratories are under investigation, such as incubating bacteria for a short time to form colonies before their identification, or rapid identification after the direct treatment of the mixtures in a bacterium-positive BC bottle. 7–11 However, the results are not consistent when different processing methods are used. 12–14 …”

Section: Introductionmentioning

confidence: 96%

Direct Identification, Antimicrobial Susceptibility Testing, and Extended-Spectrum β-Lactamase and Carbapenemase Detection in Gram-Negative Bacteria Isolated from Blood Cultures

Wen¹,

Xie²,

Liang³

et al. 2022

IDR

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Purpose To shorten the turnaround time for blood culture (BC) analyses, a rapid method was developed for the direct identification, antimicrobial susceptibility testing (AST), and multidrug resistance testing of bacteria-positive BCs. Materials and Methods The mixtures in BC bottles were treated with the multistep centrifugation method developed here and the conventional culture-based method. The bacterial sediment obtained after centrifugation was analyzed directly with MALDI-TOF MS and Vitek 2 Compact, and AST was performed directly with the Kirby–Bauer (K–B) disk diffusion, VITEK 2 Compact, and E-test methods. Extended spectrum lactamases (ESBLs) were detected with discs containing cefotaxime, cefotaxime/clavulanate, ceftazidime, and ceftazidime/clavulanate, and carbapenemase was detected with the modified carbapenem inactivation method (mCIM) and EDTA-mCIM (eCIM). Results All the results of direct testing were compared to those of the conventional methods, to evaluate the accuracy of the direct methods. The accuracies of the direct Vitek 2 Compact and MALDI-TOF MS methods were 95.5% (214/224) and 90.2% (202/224), respectively. Direct AST with K–B, Vitek 2, and E-test showed category agreement of 96.0% (2611/2721), 96.1% (2614/2721), and 97.4% (2650/2721), respectively, and the major errors and very major errors were < 2% for all three methods. In the direct determination of ESBLs, the results for cefotaxime combined with cefotaxime/clavulanate were completely consistent with those after the standard isolation method. The carbapenemase detection rate with direct mCIM and eCIM was exactly the same as that with the standard method. Conclusion These direct procedures based on multistep centrifugation are not only highly accurate but are appropriate for clinical laboratory use because the turnaround time is shorter.

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Section: Introductionmentioning

confidence: 96%

Direct Identification, Antimicrobial Susceptibility Testing, and Extended-Spectrum β-Lactamase and Carbapenemase Detection in Gram-Negative Bacteria Isolated from Blood Cultures

Wen¹,

Xie²,

Liang³

et al. 2022

IDR

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“…These culture-based methodologies are easy to perform but require the isolation of the pathogen on solid culture media after at least an 18–24 incubation period, and their sensibilities and specificities range from 84 to 100% and 91 to 100%, respectively [ 15 ]. Colorimetric assays to detect carbapenemase activity, along with bacterial identification, have also been tested using short-term cultures (STC) obtained from positive blood culture (BC) bottles showing good results [ 19 , 20 ], but no protocol has been evaluated directly from positive patients’ BC bottles. Additionally, lateral flow immunoassays are available for clinical laboratories, showing a high sensitivity and specificity, but most of them are generally expensive [ 15 ].…”

Section: Introductionmentioning

confidence: 99%

MALDI-TOF MS-Based KPC Direct Detection from Patients’ Positive Blood Culture Bottles, Short-Term Cultures, and Colonies at the Hospital

et al. 2023

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Carbapenemase resistance in Enterobacterales is a global public health problem and rapid and effective methods for detecting these resistance mechanisms are needed urgently. Our aim was to evaluate the performance of a MALDI-TOF MS-based “Klebsiella pneumoniae carbapenemase” (KPC) detection protocol from patients’ positive blood cultures, short-term cultures, and colonies in healthcare settings. Bacterial identification and KPC detection were achieved after protein extraction with organic solvents and target spot loading with suitable organic matrices. The confirmation of KPC production was performed using susceptibility tests and blaKPC amplification using PCR and sequencing. The KPC direct detection (KPC peak at approximately 28.681 Da) from patients’ positive blood cultures, short-term cultures, and colonies, once bacterial identification was achieved, showed an overall sensibility and specificity of 100% (CI95: [95%, 100%] and CI95: [99%, 100%], respectively). The concordance between hospital routine bacterial identification protocol and identification using this new methodology from the same extract used for KPC detection was ≥92%. This study represents the pioneering effort to directly detect KPC using MALDI-TOF MS technology, conducted on patient-derived samples obtained from hospitals for validation purposes, in a multi-resistance global context that requires concrete actions to preserve the available therapeutic options and reduce the spread of antibiotic resistance markers.

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“…Delay to sub-culture can result in autolysis of Streptococcus pneumoniae in the culture media [ 9 ]. One study showed that a delay of 24 h at room temperature after primary incubation had an effect on rapid identification methods with a difference demonstrated between Gram-positive and Gram-negative organisms [ 10 ]. These studies did not look at the impact of different delay times or environmental temperatures.…”

Section: Introductionmentioning

confidence: 99%

Impact of delayed processing of positive blood cultures on organism detection: a prospective multi-centre study

et al. 2022

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Background Blood cultures remain the gold standard investigation for the diagnosis of bloodstream infections. In many locations, quality-assured processing of positive blood cultures is not possible. One solution is to incubate blood cultures locally, and then transport bottles that flag positive to a central reference laboratory for organism identification and antimicrobial susceptibility testing. However, the impact of delay between the bottle flagging positive and subsequent sub-culture on the viability of the isolate has received little attention. Methods This study evaluated the impact of delays to sub-culture (22 h to seven days) in three different temperature conditions (2–8 °C, 22–27 °C and 35 ± 2 °C) for bottles that had flagged positive in automated detection systems using a mixture of spiked and routine clinical specimens. Ninety spiked samples for five common bacterial causes of sepsis (Escherichia coli, Haemophilus influenzae, Staphylococcus aureus, Streptococcus agalactiae and Streptococcus pneumoniae) and 125 consecutive positive clinical blood cultures were evaluated at four laboratories located in Cambodia, Lao PDR and Thailand. In addition, the utility of transport swabs for preserving organism viability was investigated. Results All organisms were recoverable from all sub-cultures in all temperature conditions with the exception of S. pneumoniae, which was less likely to be recoverable after longer delays (> 46–50 h), when stored in hotter temperatures (35 °C), and from BacT/ALERT when compared with BACTEC blood culture bottles. Storage of positive blood culture bottles in cooler temperatures (22–27 °C or below) and the use of Amies bacterial transport swabs helped preserve viability of S. pneumoniae. Conclusions These results have practical implications for the optimal workflow for blood culture bottles that have flagged positive in automated detection systems located remotely from a central processing laboratory, particularly in tropical resource-constrained contexts.

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The impact of delayed analysis of positive blood cultures on the performance of short-term culture followed by MALDI-TOF MS

Cited by 6 publications

References 15 publications

Direct Identification, Antimicrobial Susceptibility Testing, and Extended-Spectrum β-Lactamase and Carbapenemase Detection in Gram-Negative Bacteria Isolated from Blood Cultures

Direct Identification, Antimicrobial Susceptibility Testing, and Extended-Spectrum β-Lactamase and Carbapenemase Detection in Gram-Negative Bacteria Isolated from Blood Cultures

MALDI-TOF MS-Based KPC Direct Detection from Patients’ Positive Blood Culture Bottles, Short-Term Cultures, and Colonies at the Hospital

Impact of delayed processing of positive blood cultures on organism detection: a prospective multi-centre study

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