| Congresso Brasileiro de Microbiologia 2023 | Resumo: 532-1 | ||||
Resumo:Infections caused by Gram-negative bacilli producing carbapenemase, especially Klebsiella pneumoniae carbapenemase (KPC), are a subject of major concern. Rapid detection of KPC affects both patient treatment and infection control measures. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been proposed to assess KPC seeking for a specific peak around 28,700 Da, from cultured bacteria, but also directly from positive blood cultures. We aimed to validate this methodology from positive blood cultures of patients attended in a tertiary hospital in Porto Alegre, Brazil. We evaluated 37 consecutive blood cultures which became positive with Gram-negative bacilli (recovered from March 29 to April 27, 2023), searching for the presence of the KPC peak. To do so, a bacterial pellet was obtained by differential centrifugation process and proteins were extracted using formic acid, isopropyl alcohol and water (17:33:50). Samples were prepared using the double layer of synapinic acid method. Analyzes were performed in triplicate (3 spots per sample) using MALDI Biotyper CA System (Bruker Daltonics). We evaluated relative ions intensity (expressed in arbitrary units [a.u.]) in this mass zone after the spectra were baseline subtracted and smoothed. Isolates with i ≥120 [a.u.] were considered KPC-positive. Isolates were identified by MALDI-TOF MS (Bruker Daltonics) and Multiplex high-resolution melting real-time PCR (HRM-qPCR) was used as the reference for the detection of carbapenemases. Overall, we had 4 blaKPC- positive isolates (3 K. pneumoniae and 1 B. cepacia) and 30 blaKPC-negative (12 E. coli, 6 Acinetobacter spp., 8 K. pneumoniae, 4 E. cloacae complex, 1 B. cepacia and 2 P. aeruginosa). Using MALDI-TOF to detect KPC, we reached sensitivity and specificity of 100% and 97.0%, respectively. Indeed, we observed one false positive result (E. coli; i = 148), with no visible peak, just a background noise in the spectra. The study is still in progress to increase the number of isolates evaluated, however, this methodology already proved to be promising for KPC detection directly from positive blood cultures, reducing considerably the turn-around-time to obtain results, which may improve patient’s outcomes and infection control measures. Palavras-chave: blood culture, carbapenem-resistance, MALDI-TOF MS, KPC Agência de fomento:Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul | |||||