Stenotrophomonas maltophilia isoladas de pacientes com fibrose cística e sem fibrose cística: caracterização molecular da resistência a antimicrobianos

• Autor(a) principal: Braga, Fabrina Seger
• Data de Publicação: 2016
• 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/1/14447
• topic: Stenotrophomonas maltophilia; Antimicrobial resistance; Cystic fibrosis; Stenotrophomonas maltophilia; Resistência a antimicrobianos; Fibrose cística; Fibrose cística; Stenotrophomonas maltophilia; Resistência a antimicrobianos; CNPQ::CIENCIAS BIOLOGICAS::MICROBIOLOGIA

Stenotrophomonas maltophilia is a non-fermentative Gram negative bacillus frequent in respiratory infections, especially in patients assisted in intensive care units (ICU). It is also an important pulmonary pathogen in cystic fibrosis patients (CF). It is often multidrug resistant exhibiting resistance to a broad antimicrobial spectrum. Fluoroquinolone and trimethoprim/sulfamethoxazole (TMP-SXT) are drugs of choice for the treatment of infections caused by S. maltophilia but increasing resistance has been reported. The aim of the study was to evaluate the susceptibility and the molecular mechanisms responsible for antimicrobial resistance in S. maltophilia strains obtained from CF patients assisted in two CF reference centers and hospitalized non-cystic patients (NCF) assisted in a teaching hospital in Rio de Janeiro, Brazil. A total of 226 isolates from different clinical specimens were identified using conventional methods and evaluated by the Kirby-Bauer disk diffusion method (DD) to levofloxacin, minocycline and trimethoprim/sulfamethoxazole (TMP-SXT). The minimal inhibitory concentration (MIC) of ciprofloxacin (CIP), ceftazidime (CAZ) and TMP-SXT was determined by microdilution method according to Clinical and Laboratory Standard Institute. Polymerase Chain Reaction (PCR) analysis was performed to evaluate the expression of the sul1 (190 samples; 54 CF and 138 NCF) and qnr (A. B, S) (39 samples resistant to CIP). The samples were obtained from different specimens from January 2010 to October 2014. Fifty two samples (23%) were obtained from CF patients and most of all isolated from sputum (92.3%). The majority of 174 samples (n=77%) obtained from NCF patients were isolated from secretion/aspirate tracheal (51.5%), sputum (27%) and blood (12.1%). By DD test all samples (n=52) of CF patients were susceptible to all evaluated antimicrobials. Only 8 (4.6%) S. maltophilia strains isolated from NCF patients were resistant to TMP-SXT and levofloxacin. To determine the MIC we selected samples that showed resistance to any antimicrobial in the DD test; samples isolated from blood and one isolate for each CF patients, totaling 55 samples. Using MIC determination, CIP was the antimicrobial with the highest percentage (70,9%) of resistant strains (70,6% from CF and 76,4% from NCF). The sul1 gene was detected in one sample from NCF patient with high MIC for TMP-SXT (32µg/mL). The qnr genes (A, B and S) were not identified in this study. Most strains of S. maltophilia was isolated from patients NCF. The TMP-SXT is still the best drug of choice for the treatment of infections caused by this species. However, continuous monitoring of resistance to important antibiotics and the use of molecular methods are warranted to provide appropriate antimicrobial regimens for treating S. maltophilia infections.