Visual prognosis in infectious endophthalmitis based on rapid identification of etiologic agent by MALDI-TOF

Abstract

Purpose : To analyze the visual outcome of infectious endophthalmitis based on the etiologic agent identified by MALDI-TOF.

Methods : This prospective study included 37 patients with infectious endophthalmitis attended in a tertiary university hospital in São Paulo, Brazil, from October 2015 to June 2017. Vitreous samples were inoculated in pediatric blood culture bottles (BCBs). Positive BCBs were either seeded in culture plates and then submitted to MALDI-TOF (standard procedure) or directly submitted to MALDI-TOF after a simple in-house protein extraction protocol (direct MALDI-TOF MS). The microorganisms ID and turnaround time (TAT) by standard and direct MALDI-TOF analysis were determined and compared (student t test). Visual acuity at 3 months after diagnosis was analyzed based on the identified etiologic agent. This study was approved by Institutional Ethics Committee and followed the Helsinki declaration.

Results : The median TATs for pathogen ID by standard procedure and direct MALDI-TOF MS analysis were 50.6 h (range, 28.9 to 187.5 h) and 14.4 h (range, 3.1 to 94.0 h), respectively (p <0.0001). ID by direct MALDI-TOF was as fast as 3.1h for microrganism with high virulence, e.g. S. marcencens; for less virulent agent, such as S. epidermidis, ID by direct MALDI-TOF was less than 24 hours (Figure 1). Visual acuity better than 20/200 at month 3 was observed in 72.7% (8 out 11) of patients with S. epidermidis. Endophthalmitis caused by Gram negative agents, S. aureus and S. pneumoniae cases had poor visual prognosis (Figure 2).

Conclusions : Rapid etiologic diagnosis in infectious endophthalmitis can be obtained within 24 hours or less with direct pathogen ID of vitreous-inoculated BCBs by MALDI-TOF MS. The rapid identification of more virulent agent may impact on treatment strategy and therefore visual prognosis.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

 

Figure 1. Turnaround time (TAT) for each identified pathogen from blood culture bottles-inoculated vitreous samples of patients with infectious endophthalmiteis (black square: median TAT by MALDI-TOF; black star: median TAT by conventional culture method).

 

Figure 2. Visual acuity (VA) at 3 month after infectious endophthalmitis diagnosis and initial treatment according to identified pathogen.