Tipificação molecular de Staphylococcus aureus resistentes à meticilina isolados de infecção pulmonar crônica em pacientes com fibrose cística

• Autor(a) principal: Rodrigues, Daiana Cristina Silva
• Data de Publicação: 2019
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/14389
• topic: Methicillin-resistant Staphylococcus aureus; Cystic Fibrosis; Chronic; spa typing; Vancomycin.; Staphylococcus aureus resistente à meticilina; Fibrose Cística; Crônico; Tipificação spa; Vancomicina; Staphylococcus aureus resistentes à Meticilina-; Fibrose cística; Estafilococos aureos; Infecções estafilocócicas; Vancomicina; CNPQ::CIENCIAS BIOLOGICAS::MICROBIOLOGIA

The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) isolated from respiratory tract secretions in Cystic Fibrosis (CF) patients has risen dramatically over the past decade. Persistent MRSA infection in these patients has been associated with more rapid decline in lung function, increased hospitalization and mortality. Molecular typing studies of MRSA chronically colonizing/infecting CF patients is still scarce. The aim of this study was to perform molecular typing in MRSA isolates from 12 pediatric patients with CF chronically colonized/infected. From the results of the previous study of our group (antimicrobial resistance profile, SCCmec types, presence/absence of lukS/F genes and PFGE pulses), 80 isolates were selected for the current study. The sequencing of the X region of the protein A gene (spa) was used for molecular typing of the 80 MRSA isolates selected. Vancomycin minimum inhibitory concentration (MIC) were determined by broth microdilution in all selected isolates. The highest rates of resistance were observed to erythromycin (62/80, 77.5%), ciprofloxacin (41/80, 51.25%) and clindamycin (27/80, 33.75%); none of the isolates were resistant to linezolid. Three SCCmec types were detected: II (14/80, 17.5%), III (7/80, 8.75%) and IV (59/80, 73.75%). Only 8.75% (7/80) of the isolates were PVL positive (all SCCmec IV). Thirty-eight PFGE pulsotypes were identified in the 80 MRSA isolates, showing high genetic diversity. The most common spa types were t002 (52.5%), t539 (15%) and t779 (8.8%). We identified a new type of spa (t18066) in three isolates. Characteristically, the spa t002 was the most distributed, detected in 10 of the 12 patients. Multidrug-resistant were observed for all typed isolates as t539, t779 and t8784. Only three spa types were mapped on the ST (Sequence Type) types using SpaServer database: t002 (ST5 or ST231), t021 (ST30, ST33 or ST55) and t318 (ST30), all were positive for SCCmec IV. These results suggest a possible presence of two epidemic clones circulating in these patients: USA800/Pediatric (ST5, SCCmec IV) and Oceania Southwest Pacific Clone - OSPC (ST30, SCCmec IV). The typed isolates showed long repetitive sequences, most with more than eight repeats in the X region of the spa gene. All of the samples were susceptible to vancomycin, and the MIC for 86% of the isolates was of 1 μg/mL. We conclude that a homogeneity of spa types was observed in the isolates per patient, demonstrating a possible persistence capacity of these lineages, which contributes to the chronicity of the colonization/infection. The study of the distribution of MRSA strains in CF patients is important for implement the strategies for dissemination control.