Bloodstream and catheter-related infections due to different clones of multidrug-resistant and biofilm producer Corynebacterium striatum

Abstract

Background: Corynebacterium striatum is an emerging multidrug-resistant (MDR) pathogen associated with immunocompromised and chronically ill patients, as well as nosocomial outbreaks. In this study, we characterized 23 MDR C. striatum isolated of bloodstream and catheter-related infections from a hospital of Rio de Janeiro.

Methods: C. striatum isolates were identified by 16S rRNA and rpoB genes sequencing. The dissemination of these isolates was accomplished by pulsed-field gel electrophoresis (PFGE). All isolates were submitted to antimicrobial susceptibility testing by disk diffusion and by minimum inhibitory concentration using E-test strips methods. Antimicrobial resistance genes were detected by polymerase chain reaction. Quantitative tests were performed on four different abiotic surfaces and the ability to produce biofilm on the surface of polyurethane and silicone catheter was also demonstrated by scanning electron microscopy.

Results: Eleven PFGE profiles were found. The PFGE profile I was the most frequently observed among isolates. Five different MDR profiles were found and all PFGE profile I isolates presented susceptibility only to tetracycline, vancomycin, linezolid and daptomycin. Only the multidrug-susceptible isolate did not show mutations in the quinolone-resistance determinant region (QRDR) of the gyrA gene and was negative in the search of genes encoding antibiotic resistance. The other 22 isolates were positive to resistance genes to aminoglycoside, macrolides/lincosamides and chloramphenicol and showed mutations in the QRDR of the gyrA gene. Scanning electron microscopy illustrated the ability of MDR blood isolate partaker of the epidemic clone (PFGE profile I) to produce mature biofilm on the surface of polyurethane and silicone catheter.

Conclusions: Genotyping analysis by PFGE revealed the permanence of the MDR PFGE profile I in the nosocomial environment. Other new PFGE profiles emerged as etiologic agents of invasive infections. However, the MDR PFGE profile I was also found predominant among patients with hematogenic infections. The high level of multidrug resistance associated with biofilm formation capacity observed in MDR C. striatum is a case of concern.

Keywords: Antimicrobial multiresistance; Bacteremia; Biofilm; C. striatum; Catheter-related infection; Nosocomial outbreak.

Fig. 1

Dendrogram generated by Dice/UPGMA analysis (Bionumerics, Applied Maths) of SwaI PFGE profiles of C. striatum isolated from bloodstream infection. I- X, PFGE profiles. Previously described non-MDR isolates of PFGE types III and IV were not found in patients with blood and catheter-related infections [12]

Fig. 2

Adhesive levels, biofilm formation and survival on different types of abiotic surfaces of C. striatum (2023/PFGE profile I MDR and 2038/PFGE profile II MDR isolates) isolated from patients with bloodstream infection evaluated by quantitative tests: glass and polyurethane (hydrophilic and positively charged), polystyrene and thermanox (hydrophobic and negatively charged), and metal (catheter’s tips) surfaces. Mean values and standard deviations of three independent experiments and magnifications are shown in the figure

Fig. 3

Biofilm formation (48 h incubation) on the surface of in vitro infected polyurethane and silicone catheters by the two C. striatum isolates from bloodstream infections: (a-d) 2023/PFGE profile I isolate; (e, f) 2038/PFGE profile II isolate. (c) Microcolony formation (a hallmark of biofilm formation) by autoaggregative C. striatum on catheter surface. SEM assays of biofilm formation on (c, d) polyurethane and (e, f) silicone catheters surfaces. (d, e) Presence of hollow voids indicative of mature biofilm formation