Título

DIAGNOSTIC VALUE OF PEDIATRIC BLOOD CULTURE BOTTLE ALLIED TO MALDI-TOF MASS SPECTROMETRY IN INFECTIOUS KERATITIS

Objetivo

To evaluate the microbiological yield of corneal ulcer cultures using pediatric blood culture bottle (PBCB) and conventional culture methods in the era of Matrix-assisted laser desorption ionization time of flight (MALDI-TOF) mass spectrometry (MS).

Método

Prospective study including patients clinically diagnosed with infectious keratitis between 2019 and 2023 at a tertiary referral center in Brazil. Inclusion criteria were corneal ulcers larger than 2 mm in size, centrally located or unresponsive to previous treatment. Corneal scrapes from each patient were cultured in PBCBs (BACTEC Plus Aerobic/F, BD Diagnostics, USA) and in conventional culture media, which included thioglycolate broth, brain heart infusion broth with antibiotics, blood agar, chocolate agar and Sabouraud dextrose agar. Pathogens isolated from positive samples were identified and analyzed using MALDI-TOF MS.

Resultado

A total of 154 patients were included in this study. 49% of the patients were already using antibiotics eyedrops at the time of corneal scrape (Table 1). The growth rates for PBCBs and the conventional media were similar (41% and 43%, respectively, p=0.56). Culture results were similar between PBCBs and conventional media in 76% of the cases. The most common isolated agent was Pseudomonas aeruginosa in both methods (23% and 21%, respectively) – Table 2. The overall growth rate for the two methods combined was 51%.

Conclusão

PBCB allied to MALDI-TOF MS is an alternative diagnostic tool in assessing infectious keratitis. Considering the high percentage of agreement between results, this technique is reliable and could potentially replace the traditional approach. It would save time, reduce the number of corneal scrapes, and potentially lower the risk of contamination. This method is especially suitable for office settings and remote clinics, as there is no need to maintain a supply of fresh agar media, but it can also be useful in hospital setting as it can increase growth rate when used adjunctively.