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

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

Second Virtual International Symposium on Cellular and Organismal Stress Responses, September 8–9, 2022 [Meeting Review]

The Second International Symposium on Cellular and Organismal Stress Responses took place virtually on September 8–9, 2022. This meeting was supported by the Cell Stress Society International (CSSI) and organized by Patricija Van Oosten-Hawle and Andrew Truman (University of North Carolina at Charlotte, USA) and Mehdi Mollapour (SUNY Upstate Medical University, USA). The goal of this symposium was to continue the theme from the initial meeting in 2020 by providing a platform for established researchers, new investigators, postdoctoral fellows, and students to present and exchange ideas on various topics on cellular stress and chaperones. We will summarize the highlights of the meeting here and recognize those that received recognition from the CSSI

Effect of the emergence of community acquired methicillin resistant Staphylococcus aureus on microbial resistance patterns seen during a seven year study of minocycline/rifampin catheter use

Background. Health care associated catheter related blood stream infections (CRBSI) represent a significant public health concern in the United States. Several studies have suggested that precautions such as maximum sterile barrier and use of antimicrobial catheters are efficacious at reducing CRBSI, but there is concern within the medical community that the prolonged use of antimicrobial catheters may be associated with increased bacterial resistance. Clinical studies have been done showing no association and a significant decrease in microbial resistance with prolonged minocycline/rifampin (M/R) catheter use. One explanation is the emergence of community acquired methicillin resistant Staphylococcus aureus (MRSA), which is more susceptible to antibiotics, as a cause of CRBSI. Methods. Data from 323 MRSA isolates cultured from cancer patients at The University of Texas MD Anderson Cancer center from 1997-2007 displaying MRSA infection were analyzed to determine whether there is a relationship between resistance to minocycline and rifampin and prolonged wide spread use of minocycline (M/R) catheters. Analysis was also conducted to determine whether there was a significant change in the prevalence community acquired MRSA (CA-MRSA) during this time period and if this emergence act as a confounder masquerading the true relationship between microbial resistance and prolonged M/R catheter use. Results. Our study showed that the significant (p=0.008) change in strain type over time is a confounding variable; the adjusted model showed a significant protective effect (OR 0.000281, 95% CI 1.4x10 -4-5.5x10-4) in the relationship between MRSA resistance to minocycline and prolonged M/R catheter use. The relationship between resistance to rifampin and prolonged M/R catheter use was not significant. Conclusion. The emergence of CA-MRSA is a confounder and in the relationship between resistance to minocycline and rifampin and prolonged M/R catheter use. However, despite the adjustment for the more susceptible CA-MRSA the widespread use of M/R catheters does not promote microbial resistance

Catheter Complications in Cancer Patients Receiving Parenteral Nutrition: Potential for an Effective, Non-Antibiotic, Antimicrobial Catheter Lock Solution Based on Nitroglycerin, Citrate and Ethanol as a Preventative Intervention

Background – Patient receiving parenteral nutrition (PN) are at high risk for catheter complications including catheter related infections, catheter occlusions, and venous thrombosis. Several interventions such as antimicrobial lock therapy (ALT) have been used to prevent catheter related infections. However there are currently no ALTs approved for use in the United States, resulting in off-label use of antibiotics, antifungals, or ethanol as ALT. The aims of this dissertation are to synthesize and evaluate the rates of catheter complications, causative organisms, and risk factors in the current literate and in patients receiving PN at a tertiary cancer center. Additionally, in vitro efficacy of microbial biofilm eradication and anti-thrombogenic properties were evaluated for Nitrogylcerin + Citrate + Ethanol (NiCE) ALT. Methods – Three studies were conducted including 1) a systematic review of literature published in Medline, Embase, and CINAHAL between January 2012 to January 2017 regarding rates, risk factors, and/or prevention strategies via ALT for catheter complications among patients receiving PN; 2) a retrospective cohort study among cancer patients receiving inpatient PN between January 2013 and January 2015 at the University of Texas MD Anderson Cancer Center assessing rates of infectious complications, prevalence and time-to-infection of causative pathogens, and identify risk factors for catheter complications among all cases and a random sample of controls; and 3) an in vitro assessment of NiCE evaluating efficacy of eradication of microbial biofilm formed by pathogens commonly associated with catheter related infections. Anti-thrombogenic properties of NiCE compared to standard of care was also assessed. Results – Thirty-seven studies were included in the systematic review. Studies were grouped by definition infection including catheter-related bloodstream infection (CRBSI) and central line associated blood stream infection (CLABSI). Random effects summary rates per 1000 catheter days were 0.8 CRBSI episodes (95% CI 0.21-3.11) and 3.17 CLABSI episodes (95% CI 1.82-5.51). Use of taurolidine or ethanol ALT were efficacious in reducing infection however, several studies has concerns of adverse mechanical complications. Retrospective analyses showed a total of 46 CLABSI cases in 38 of the 1,762 patients that received PN (1.73 episodes/1000 parenteral nutrition days). Gram-positive (37.8%) and yeast (29.7%) were the most common CLABSI pathogens. Non-infectious catheter complications occurred in 38.6% (n=56) of patients included in the sample. Multivariate analysis identified age, GVHD, and history of occlusion in the same catheter, as well as intestinal failure and long-term PN use as significant risk factors for CLABSI and non-infectious complications, respectively. Finally, NiCE showed significant efficacy by complete eradication of common gram-positive, gram-negative, and yeast pathogens embedded in biofilm. When compared to taruolidine + citrate + heparin ALT, NiCE was significantly superior in eradicating both Staphylococcus aureus and Candida glabrata embedded in biofilm. NiCE also showed equivocal anti-thrombogenic properties when compared to heparin standard of care. Conclusions – Patients receiving PN are at risk for both infectious and non-infectious catheter complications. ALT shows promise for prevention of catheter complications, however risks of microbial resistance and mechanical complications make antibiotic/antifungal and ethanol lock not an ideal candidate for universal prophylaxis. Until candidate ALT with less risks is available, a better understanding of risk factors, pathogens, and source of infections will allow clinicians to weigh risks and benefits of available ALTs for targeted infection prevention in higher risk sub-populations. NiCE ALT demonstrates rapid broad-spectrum biofilm eradication as well as effective anticoagulant activity making NiCE a high-quality ALT candidate for clinical assessment