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Using MALDI-TOF-MS to test Staphylococcus aureus-infected vitreous
Zhenyu Song1, Xiuping Liu1, Minyu Zhu1
1Zhongshan Ophthalmic Center, State Key Laboratory of Ophthalmology, the Key Lab of Ophthalmology and Visual Science of Guangdong, Sun Yat-sen University, Guangzhou, China.
Molecular Vision
|July 27, 2017
Summary
This study presents a rapid method for detecting Staphylococcus aureus in endophthalmitis vitreous samples using matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS). This technique aids in faster diagnosis and earlier treatment for patients.
Area of Science:
- Microbiology
- Ophthalmology
- Analytical Chemistry
Background:
- Endophthalmitis is a severe intraocular infection often caused by Staphylococcus aureus.
- Accurate and rapid identification of the causative pathogen is crucial for effective treatment.
- Conventional diagnostic methods for vitreous samples can be time-consuming.
Purpose of the Study:
- To develop and validate a simple, fast, and sensitive method for detecting Staphylococcus aureus in endophthalmitis vitreous samples.
- To utilize matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) for direct pathogen identification.
Main Methods:
- Staphylococcus aureus was inoculated into porcine eyes or mixed with homogenized vitreous samples.
- Vitreous samples underwent homogenization, with or without centrifugation, followed by Gram staining and Coomassie Blue staining.
- Pellets from homogenized vitreous were analyzed using MALDI-TOF-MS.
Main Results:
- The minimum detectable level of Staphylococcus aureus in homogenized vitreous pellets was 1.0 × 10^4 CFU/μl with a 100% positive rate for inoculated samples.
- MALDI-TOF-MS successfully identified Staphylococcus aureus in vitreous pellets when the inoculated number was 1.0 × 10^4 CFU/μl or higher.
- Gram staining showed traces of bacteria in the supernatant, while blood agar cultures yielded few colonies from the supernatant and intensive colonies from the pellet.
Conclusions:
- A reliable method combining simple extraction with MALDI-TOF-MS for direct Staphylococcus aureus testing from vitreous samples was established.
- This rapid identification technique is adaptable for clinical routine, potentially reducing diagnostic delays.
- Early therapeutic intervention in endophthalmitis patients can be facilitated by this faster diagnostic approach.
