Rhodococcus Bacteremia in Cancer Patients Is Mostly Catheter Related and Associated with Biofilm Formation

Abstract

Rhodococcus is an emerging cause of opportunistic infection in immunocompromised patients, most commonly causing cavitary pneumonia. It has rarely been reported as a cause of isolated bacteremia. However, the relationship between bacteremia and central venous catheter is unknown. Between 2002 and 2010, the characteristics and outcomes of seventeen cancer patients with Rhodococcus bacteremia and indwelling central venous catheters were evaluated. Rhodococcus bacteremias were for the most part (94%) central line-associated bloodstream infection (CLABSI). Most of the bacteremia isolates were Rhodococcus equi (82%). Rhodococcus isolates formed heavy microbial biofilm on the surface of polyurethane catheters, which was reduced completely or partially by antimicrobial lock solution. All CLABSI patients had successful response to catheter removal and antimicrobial therapy. Rhodococcus species should be added to the list of biofilm forming organisms in immunocompromised hosts and most of the Rhodococcus bacteremias in cancer patients are central line associated.

Biofilm formation by Rhodococcus equi and putative association with macrolide resistance

“…To the best of our knowledge, there are three studies regarding R. equi biofilm formation that together evaluated only ten isolates, six clinical (associated to chronic infection in humans) (Akhrass et al 2012, Remuzgo-Martínez et al 2013) and four from soil (Mart`yanov et al 2014). Akhrass et al (2012) found three strains positive for biofilm formation, while Remuzgo-Martínez et al (2013) verified only one.…”

“…In the present study, R. equi in established biofilms were recovered even after exposure to high ATM concentrations, however, CFU amount reduction was statically significant (Table 3). Two studies concerning antimicrobial susceptibility of clinical and environmental R. equi producing biofilm were performed by Akhrass et al (2012) and Mart`yanov et al (2014). The first study found R. equi biofilm reduced completely or partially by antimicrobial solutions.…”

“…In this respect, the ability to form biofilm has been evaluated in R. equi isolates from humans showing bacteremia after prolonged treatment (Akhrass et al 2012, Remuzgo-Martínez et al 2013. The currently therapy of equine rhodococcosis consist of macrolide associated to rifampin, for which there is emergence of resistance (Giguère et al 2010).…”

Conjugal Transfer of a Virulence Plasmid in the Opportunistic Intracellular Actinomycete Rhodococcus equi

“…Biofilms are multicellular structures which are relevant clinically because of their extreme resistance to antibiotic therapy and are thus difficult to treat, even if the identical sessile cells are antibiotic susceptible (38). Significantly, biofilm formation by R. equi was recently reported, where biofilms formed on catheters were found to be the source of Rhodococcus bacteremia in cancer patients (2). Studies are under way in our laboratory to investigate the possible relationship between conjugation and biofilm formation in R. equi.…”

Stability and compatibility of antimicrobial lock solutions

“…Methylene blue (0.05-0.15%) has been used for ALT in combination with 0.15% methyl paraben, 0.015% propyl paraben, and TSC 70 mg/mL or heparin sodium 10 units/mL, with no incompatibilities noted. 10,[98][99][100][101] The use of methylene blue in ALT has not become widespread due to a relative lack of supportive data and logistical issues.…”