Rapid pathogen identification and antimicrobial susceptibility testing in in vitro endophthalmitis with matrix assisted laser desorption-ionization Time-of-Flight Mass Spectrometry and VITEK 2 without prior culture

Autoři: Lindsay Y. Chun aff001;  Laura Dolle-Molle aff002;  Cindy Bethel aff002;  Rose C. Dimitroyannis aff001;  Blake L. Williams aff001;  Sidney A. Schechet aff001;  Seenu M. Hariprasad aff001;  Dominique Missiakas aff003;  Olaf Schneewind aff003;  Kathleen G. Beavis aff002;  Dimitra Skondra aff001
Působiště autorů: Department of Ophthalmology and Visual Science, The University of Chicago Hospitals and Health System, Chicago, Illinois, United States of America aff001;  Clinical Microbiology Laboratory, The University of Chicago Hospitals and Health System, Chicago, Illinois, United States of America aff002;  Department of Microbiology, The University of Chicago, Chicago, Illinois, United States of America aff003;  Department of Pathology, The University of Chicago Hospitals and Health System, Chicago, Illinois, United States of America aff004
Vyšlo v časopise: PLoS ONE 14(12)
Kategorie: Research Article
doi: https://doi.org/10.1371/journal.pone.0227071



Prompt clinical diagnosis and initiation of treatment are critical in the management of infectious endophthalmitis. Current methods used to identify causative agents of infectious endophthalmitis are mostly inefficient, owing to suboptimal sensitivity, length, and cost. Matrix Assisted Laser Desorption-Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) can be used to rapidly identity pathogens without a need for culture. Similarly, automated antimicrobial susceptibility test systems (AST, VITEK 2) provide accurate antimicrobial susceptibility profiles. In this proof-of-concept study, we apply these technologies for the direct identification and characterization of pathogens in vitreous samples, without culture, as an in vitro model of infectious endophthalmitis.


Vitreous humor aspirated from freshly enucleated porcine eyes was inoculated with different inocula of Staphylococcus aureus (S. aureus) and incubated at 37°C. Vitreous endophthalmitis samples were centrifuged and pellets were directly analyzed with MALDI-TOF MS and VITEK 2 without prior culture. S. aureus colonies that were conventionally grown on culture medium were used as control samples. Time-to-identification, minimum concentration of bacteria required for identification, and accuracy of results compared to standard methods were determined.


MALDI-TOF MS achieved accurate pathogen identification from direct analysis of intraocular samples with confidence values of up to 99.9%. Time from sample processing to pathogen identification was <30 minutes. The minimum number of bacteria needed for positive identification was 7.889x106 colony forming units (cfu/μl). Direct analysis of intraocular samples with VITEK 2 gave AST profiles that were up to 94.4% identical to the positive control S. aureus analyzed per standard protocol.


Our findings demonstrate that the direct analysis of vitreous samples with MALDI-TOF MS and VITEK 2 without prior culture could serve as new, improved methods for rapid, accurate pathogen identification and targeted treatment design in infectious endophthalmitis. In vivo models and standardized comparisons against other microbiological methods are needed to determine the value of direct analysis of intraocular samples from infectious endophthalmitis with MALDI-TOF MS and VITEK 2.

Klíčová slova:

Antibiotics – Antimicrobial resistance – Bacterial pathogens – Cataract surgery – Eyes – Matrix-assisted laser desorption ionization time-of-flight mass spectrometry – Pathogens – Staphylococcus aureus


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2019 Číslo 12
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