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Sulaiman IM, Miranda N, Hook W, Mendoza J, Kumfert Q, Barnes T, Sung K, Khan S, Nawaz M, Banerjee P, Simpson S, Karem K. A Single-Laboratory Performance Evaluation of MALDI-TOF MS in Rapid Identification of Staphylococcus aureus, Cronobacter sakazakii, Vibrio parahaemolyticus, and Some Closely Related Bacterial Species of Public Health Importance. J AOAC Int 2023; 106:1574-1588. [PMID: 37725340 DOI: 10.1093/jaoacint/qsad109] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 08/21/2023] [Accepted: 09/10/2023] [Indexed: 09/21/2023]
Abstract
BACKGROUND Staphylococcus is a genus of Gram-positive bacteria, known to cause food poisoning and gastrointestinal illness in humans. Additionally, the emergence of methicillin-resistant S. aureus (MRSA) strains has caused a major health care burden worldwide. Cronobacter is a group of Gram-negative bacteria that can survive in extreme dry conditions. Cronobacter sakazakii is known to contaminate powdered infant formula and cause life-threatening infections in neonates. Vibrio is a genus of human-pathogenic Gram-negative bacteria that can cause foodborne illness by consuming undercooked or raw seafood. Vibrio parahaemolyticus can cause serious gastrointestinal disease in humans. Thus, rapid identification of Staphylococcus spp., Cronobacter spp., and Vibrio spp. is crucial for the source tracking of contaminated food, as well as to measure the transmission dynamics of these bacterial pathogens causing foodborne diseases and outbreaks. OBJECTIVE This single-laboratory performance evaluation study used the VITEK MS system to evaluate the potential of MALDI-TOF MS technology for rapid identification of S. aureus-like, C. sakazakii-like, and V. parahaemolyticus-like isolates of public health importance. METHOD A total of 226 isolates recovered from various food, environmental surveillance samples, and other sources were identified by bioMérieux VITEK 2 and VITEK MS systems as Staphylococcus spp., Cronobacter spp., and Vibrio spp. Five American Type Culture Collection (ATCC) reference Gram-positive and Gram-negative bacterial isolates were also tested to complete the study. In addition, for some Staphylococcus spp. isolates, whole genome sequencing (WGS) and DNA sequencing of 16S rRNA partial region were also performed for species identification. RESULTS The VITEK MS system was able to provide species identification to all 96 isolates of Staphylococcus spp. and to all 29 isolates of Vibrio spp. examined with a high confidence value (99.9%). Similarly, species identification was observed for the majority of spots (245 of 303) for the 101 Cronobacter spp. isolates (∼82.0%) with a high confidence value (99.9%), and genus level identification was noticed for the rest of the Cronobacter spp. isolates (18.0%; 58 of the 303 spots) analyzed. Species identification data generated by VITEK 2 system were comparable to data obtained by the VITEK MS system. CONCLUSIONS The VITEK MS system is a reliable high-throughput platform that can rapidly identify Staphylococcus, Vibrio, and Cronobacter to the genus level, as well as S. aureus, C. sakazakii, V. parahaemolyticus, and other closely related foodborne isolates and bacterial isolates from additional sources, in most cases. HIGHLIGHTS The VITEK MS system can be used in the rapid genus and species identification of human-pathogenic Staphylococcus spp., Cronobacter spp., and Vibrio spp. isolates.
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Affiliation(s)
- Irshad M Sulaiman
- Microbiological Sciences Branch, Atlanta Human and Animal Food Laboratory, Office of Regulatory Science, Office of Regulatory Affairs, U.S. Food and Drug Administration, 60 Eighth Street NE, Atlanta, GA 30309, USA
| | - Nancy Miranda
- Microbiological Sciences Branch, Atlanta Human and Animal Food Laboratory, Office of Regulatory Science, Office of Regulatory Affairs, U.S. Food and Drug Administration, 60 Eighth Street NE, Atlanta, GA 30309, USA
| | - Whitney Hook
- Microbiological Sciences Branch, Atlanta Human and Animal Food Laboratory, Office of Regulatory Science, Office of Regulatory Affairs, U.S. Food and Drug Administration, 60 Eighth Street NE, Atlanta, GA 30309, USA
| | - Joseph Mendoza
- Microbiological Sciences Branch, Atlanta Human and Animal Food Laboratory, Office of Regulatory Science, Office of Regulatory Affairs, U.S. Food and Drug Administration, 60 Eighth Street NE, Atlanta, GA 30309, USA
| | - Quincy Kumfert
- University of California, 1 Shields Avenue, Davis, CA 95616, USA
| | - Tamayo Barnes
- Microbiological Sciences Branch, Atlanta Human and Animal Food Laboratory, Office of Regulatory Science, Office of Regulatory Affairs, U.S. Food and Drug Administration, 60 Eighth Street NE, Atlanta, GA 30309, USA
| | - Kidon Sung
- Division of Microbiology, National Center for Toxicological Research, U.S. Food and Drug Administration, 3900 NCTR Road, Jefferson, AR 72079, USA
| | - Saeed Khan
- Division of Microbiology, National Center for Toxicological Research, U.S. Food and Drug Administration, 3900 NCTR Road, Jefferson, AR 72079, USA
| | - Mohamed Nawaz
- Division of Microbiology, National Center for Toxicological Research, U.S. Food and Drug Administration, 3900 NCTR Road, Jefferson, AR 72079, USA
| | - Pratik Banerjee
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, 1302 W. Pennsylvania Avenue, Urbana, IL 61801, USA
| | - Steven Simpson
- Microbiological Sciences Branch, Atlanta Human and Animal Food Laboratory, Office of Regulatory Science, Office of Regulatory Affairs, U.S. Food and Drug Administration, 60 Eighth Street NE, Atlanta, GA 30309, USA
| | - Kevin Karem
- Microbiological Sciences Branch, Atlanta Human and Animal Food Laboratory, Office of Regulatory Science, Office of Regulatory Affairs, U.S. Food and Drug Administration, 60 Eighth Street NE, Atlanta, GA 30309, USA
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Voellmy IK, Lang C, Gasser M, Kronenberg A. Antibiotic resistance surveillance of Klebsiella pneumoniae complex is affected by refined MALDI-TOF identification, Swiss data, 2017 to 2022. Euro Surveill 2022; 27. [PMID: 36367012 PMCID: PMC9650708 DOI: 10.2807/1560-7917.es.2022.27.45.2200104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Background Modern laboratory methods such as next generation sequencing and MALDI-TOF allow identification of novel bacterial species. This can affect surveillance of infections and antimicrobial resistance. From 2017, increasing numbers of medical microbiology laboratories in Switzerland differentiated Klebsiella variicola from Klebsiella pneumoniae complex using updated MALDI-TOF databases, whereas many laboratories still report them as K. pneumoniae or K. pneumoniae complex. Aim Our study explored whether separate reporting of K. variicola and the Klebsiella pneumoniae complex affected the ANRESIS surveillance database. Methods We analysed antibiotic susceptibility rates and specimen types of K. variicola and non-K. variicola-K. pneumoniae complex isolates reported by Swiss medical laboratories to the ANRESIS database (Swiss Centre for Antibiotic Resistance) from January 2017 to June 2022. Results Analysis of Swiss antimicrobial resistance data revealed increased susceptibility rates of K. variicola compared with species of the K. pneumoniae complex other than K. variicola in all six antibiotic classes tested. This can lead to underestimated resistance rates of K. pneumoniae complex in laboratories that do not specifically identify K. variicola. Furthermore, K. variicola strains were significantly more often reported from blood and primarily sterile specimens than isolates of the K. pneumoniae complex other than K. variicola, indicating increased invasiveness of K. variicola. Conclusion Our data suggest that refined differentiation of the K. pneumoniae complex can improve our understanding of its taxonomy, susceptibility, epidemiology and clinical significance, thus providing more precise information to clinicians and epidemiologists.
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Affiliation(s)
- Irene Katharina Voellmy
- Swiss Centre for Antibiotic Resistance ANRESIS, Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | | | - Michael Gasser
- Swiss Centre for Antibiotic Resistance ANRESIS, Institute for Infectious Diseases, University of Bern, Bern, Switzerland
| | - Andreas Kronenberg
- Swiss Centre for Antibiotic Resistance ANRESIS, Institute for Infectious Diseases, University of Bern, Bern, Switzerland
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Kim JM, Chung SH, Kim I, Kim JS. Comparison of peaks in the matrix-assisted laser desorption ionization time-of-flight mass spectrometry spectra of Staphylococcus aureus grown on various blood agar plates. J Microbiol Methods 2022; 196:106471. [PMID: 35460710 DOI: 10.1016/j.mimet.2022.106471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 04/14/2022] [Accepted: 04/14/2022] [Indexed: 12/27/2022]
Abstract
Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) is routinely used for bacterial identification in clinical laboratories. Bacterial protein expression may differ according to their growth conditions, especially the culture medium composition. We aimed to study the peak variations of Staphylococcus aureus grown on various blood agar plates (BAP), especially phenol-soluble modulin-mec (PSM-mec) peak (m/z 2409) associated with mecA gene conferring methicillin resistance. Methicillin-resistant S. aureus (MRSA) ATCC 43300 and eight clinical MRSA isolates were cultured on various commercial BAPs including tryptic soy agar-based BAPs, Columbia agar-based BAP and in-house BAPs with the addition of yeast extract. Analysis of the MALDI-TOF peaks of S. aureus, cultured on various BAPs, revealed the peak intensities of low-molecular weight proteins to vary depending on the composition of BAPs, especially the presence or absence of yeast extract. Especially, the PSM-mec and delta-toxin peaks showed low intensity for S. aureus ATCC 43300 and clinical isolates. No significant differences were found in the number of peaks, but some peaks had lower intensity, corresponding to the medium containing yeast extract, in low-mass region (<m/z 4000). BAPs based on tryptic soy agar rather than Columbia agar seems to be appropriate for the detection of PSM-mec, a methicillin resistance marker of S. aureus and delta-toxin, an agr function indicator.
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Affiliation(s)
- Jung-Min Kim
- Department of Laboratory Medicine, Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Republic of Korea
| | - Sung Hee Chung
- Department of Laboratory Medicine, Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Republic of Korea
| | - Inhee Kim
- Department of Laboratory Medicine, Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Republic of Korea
| | - Jae-Seok Kim
- Department of Laboratory Medicine, Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Republic of Korea.
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Investigation of MALDI-TOF Mass Spectrometry for Assessing the Molecular Diversity of Campylobacter jejuni and Comparison with MLST and cgMLST: A Luxembourg One-Health Study. Diagnostics (Basel) 2021; 11:diagnostics11111949. [PMID: 34829296 PMCID: PMC8621691 DOI: 10.3390/diagnostics11111949] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 10/15/2021] [Accepted: 10/17/2021] [Indexed: 11/17/2022] Open
Abstract
There is a need for active molecular surveillance of human and veterinary Campylobacter infections. However, sequencing of all isolates is associated with high costs and a considerable workload. Thus, there is a need for a straightforward complementary tool to prioritize isolates to sequence. In this study, we proposed to investigate the ability of MALDI-TOF MS to pre-screen C. jejuni genetic diversity in comparison to MLST and cgMLST. A panel of 126 isolates, with 10 clonal complexes (CC), 21 sequence types (ST) and 42 different complex types (CT) determined by the SeqSphere+ cgMLST, were analysed by a MALDI Biotyper, resulting into one average spectra per isolate. Concordance and discriminating ability were evaluated based on protein profiles and different cut-offs. A random forest algorithm was trained to predict STs. With a 94% similarity cut-off, an AWC of 1.000, 0.933 and 0.851 was obtained for MLSTCC, MLSTST and cgMLST profile, respectively. The random forest classifier showed a sensitivity and specificity up to 97.5% to predict four different STs. Protein profiles allowed to predict C. jejuni CCs, STs and CTs at 100%, 93% and 85%, respectively. Machine learning and MALDI-TOF MS could be a fast and inexpensive complementary tool to give an early signal of recurrent C. jejuni on a routine basis.
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