Atividade de biocidas e produção de biofilme em Corynebacterium striatum

Abstract

Corynebacterium striatum has been linked to a number of cases of nosocomial infections, sometimes fatal, mainly in immunocompromised patients that use invasive devices. The occurrence of outbreaks in nosocomial environments caused by clones multi-resistant to antimicrobial agents (MDR) may include C. striatum among pathogens responsible for infections related to the health service (IRAS). Until now, studies focused on the investigation of virulence factors that may contribute to IRAS caused by C. striatum were not found in the literature. Accordingly, we investigated the biofilm production on inert solid surfaces and the susceptibility to biocidal products by planktonic and sessile forms of 14 strains of C. striatum of pulsotypes I-IV that were isolated during an nosocomial outbreak in the metropolitan region of Rio de Janeiro. Micro-organisms showed the ability to adhere to abiotic, hydrophilic, hydrophobic and metallic surfaces at different intensities. The epidemic clone (PFGE I-MDR) demonstrated a greater capacity to adhere to glass, plastic and metal surfaces. The scanning electron microscopy assays confirmed the ability to produce mature biofilms on polyurethane catheters by C. striatum of pulsotypes I, II, III e IV. The susceptibility to biocides was assessed by the disk diffusion and Time Kill methods. Results of the disk-diffusion screening test showed zones of inhibition with reduced diameters for C. striatum strains that remained viable in the presence of biocides when evaluated by the Time Kill test. Susceptibility profiles of planktonic forms to glutaraldehyde 2%, peracetic acid 1%, Virkon 1%, sodium hypochlorite 1%, chlorhexidine 2%, benzalkonium chloride sodium sulphate 2%, ethyl alcohol 70% and iodized alcohol (70/1%) were assessed by the Time Kill test at incubation times of 5, 10, 15 and 30 minutes. C. striatum showed tolerance to biocides for reduced periods of time (0,5< t <4 min) when compared to the tolerance (30 minutes) observed with glutaraldehyde 2% solution. C. striatum 1961/III MDS was the one that presented tolerant planktonic forms for the longest period of time for all the tested biocides, including glutaraldehyde 2% and ethyl alcohol 70% for 30 minutes. The lowest tolerance registered was for sodium hypochlorite and Virkon, especially of 2369/II-MDR and 1954/IV-MDS strains . The majority of the C. striatum samples also presented resistance to the antiseptics alcohol 70% and iodized alcohol (70/1%). The sample 1954/IV - MDS presented tolerance to all the disinfectants and antiseptics tested. C. striatum (pulsotypes I, II, III e IV) remained capable of producing biofilm on the surface of different abiotic substrates in the presence of glutaraldehyde 2% (30 min) and alcohol (30 min), indicating that planktonic and sessile forms of C. striatum were capable of surviving the treatments with different biocidal products. The presence of bovine serum albumin 2% enhanced the tolerance to biocides of both planktonic and sessile forms of C. striatum. In conclusion, biofilm production together with the tolerance to biocides used in nosocomial environment can contribute to the establishment and dissemination of IRAS caused by C. striatum, independent of antibiotics susceptibility profiles