| Congresso Brasileiro de Microbiologia 2023 | Resumo: 406-1 | ||||
Resumo:Corynebacterium striatum, initially considered only as part of the human microbiota, has been recognized as a potentially pathogenic microorganism. In recent decades, an increasing number of invasive infections caused by multidrug-resistant (MDR) and susceptible strains of C. striatum have been observed. The number of cases of C. striatum infection has increased in developed countries, and in developing countries like Brazil. Epidemic outbreaks caused by MDR strains of C. striatum have been documented in patients hospitalized for long periods and/or continuously exposed to antimicrobials. The increase in bacterial resistance to antimicrobials is a global health problem. Several studies have shown increased antimicrobial resistance among corynebacteria. To date, vancomycin, teicoplanin, and linezolid are the most effective against corynebacteria. In 2013, characteristics of C. striatum strains, isolated during an outbreak in 2009, at the Pedro Ernesto University Hospital, Rio de Janeiro, were described. The pathogen was isolated from different sectors of the hospital, in different anatomical sites. Microorganisms deal with different conditions, which lead them to change phenotypically, through gene expression conditioned to each situation. This expression can be altered by oxidative stress, induced by metals such as Fe2+ and Fe3+ that participate in Fenton's reactions and generate reactive oxygen species. Several virulence factors are regulated by iron; however, little is known about the relationship between iron availability and antimicrobial resistance. The aim of the study was to investigate the influence on C. striatum of iron restriction and supplementation conditions in relation to antimicrobial susceptibility. Ten strains were used, isolated during and after the outbreak and classified into ten profiles. Bacterial suspensions were cultured in TSB under conditions of restriction and iron supplementation: (i) addition of aliquots of 2,2'-dipyridyl chelating solution; (ii) addition of FeSO4. For analyzing the sensitivity profiles, suspensions were prepared at a concentration of 0.5 on the McFarland scale. Profiles I, II, V, VI, VII, VIII and IX were identified as MDR, showing sensitivity only to linezolid, vancomycin and tetracycline. Profiles III and IV were identified as sensitive, resistant only to fosfomycin, mupirocin and ticarcillin/clavulanate. Iron limitation altered susceptibility profiles to nine antimicrobials. All strains, under any conditions, were sensitive to vancomycin and linezolid. Five, previously resistant to moxifloxacin, became sensitive after iron supplementation. Five strains that were tetracycline-sensitive became resistant; one strain became tetracycline-sensitive. Regarding rifampicin, iron supplementation changed the profiles of three strains from resistant to sensitive and the profile of one strain from sensitive to resistant, induced sensitivity and resistance to clindamycin in two strains, respectively. Changes in iron levels produced changes in susceptibility profiles, especially to moxifloxacin, which proved to be effective against strains I, II, V, VI and VIII, hither to resistant to its activity, both under limitation and iron supplementation. The X-profile strain, which was resistant to only two antimicrobials, became resistant to nine (iron limitation) and eight antimicrobials (iron supplementation), demonstrating that there is an iron-mediated regulation of sensitivity to antimicrobials. Palavras-chave: Antimicrobials, Corynebacterium striatum, Iron, Multidrug-resistance, Nosocomial outbreak Agência de fomento:CAPES, CNPq, FAPERJ | |||||