Journal Club

In this feature, a panel of IDSA members identifies and critiques important new studies in the current literature that have a significant impact on the practice of infectious diseases medicine

• Using Lock Therapy to Treat Long-Term Catheter-Related Infections
• Eosinopenia as a Marker for C. difficile Severity

Click here for the previous edition of Journal Club. For a review of other recent research in the infectious diseases literature, see “In the Literature,”  by Stanley Deresinski, MD, FIDSA, in each issue of Clinical Infectious Diseases.

Using Lock Therapy to Treat Long-Term Catheter-Related Infections

Reviewed by Zeina A. Kanafani, MD, MS, FIDSA

A recent study in Antimicrobial Agents and Chemotherapy evaluated the efficacy of antibiotic lock therapy (ALT) in the treatment of long-term catheter-related infections caused by multidrug-resistant (MDR) pathogens.

All patients with long-term central venous catheters (LTCVC) were followed prospectively and those who developed infections were included in the analysis. The investigators followed an institutional protocol that dictates that bloodstream infections (BSI) caused by Gram-negative bacilli (GNB) or coagulase-negative staphylococci are treated using ALT in addition to systemic antimicrobial therapy. Such patients must not have evidence of tunnel infection, pocket infection, severe sepsis, septic shock, endocarditis, septic thrombophlebitis, osteomyelitis, or another complicated infection. ALT uses vancomycin at 5 mg/ml and amikacin at 2 mg/ml, which are introduced into all CVC lumens and changed every 24 hours.

The analysis included 296 LTCVC infections in 275 patients, with 62 patients receiving ALT. The population of ALT-treated patients included 12 patients with MDR infections (five with extended-spectrum β-lactamase producing E. coli, three with carbapenem-resistant A. baumannii, two with vancomycin-resistant E. faecium, one with methicillin-resistant S. aureus, and one with carbapenem-resistant P. aeruginosa).

The overall treatment failure or recurrence rate was 35.4 percent. In the ALT group, 22 patients required LTCVC removal, and the proportion of treatment failure or recurrence was 24.1 percent. When looking at risk factors for treatment failure or relapse, ALT use as initial therapy was a protective factor on multivariable analysis (odds ratio [OR] 0.44; 95 percent confidence interval [CI] 0.21-0.94; P = 0.03). The 30-day mortality in the overall patient population was 23.6 percent. Independent predictors of death included being in palliative care, having an infection with an MDR pathogen, and having a high sequential organ failure assessment (SOFA) score. Conversely, factors associated with a lower risk of death were having a hematologic malignancy, adherence to treatment protocol, and receiving ALT (OR 0.29; 95 percent CI 0.09-0.94; P = 0.04).

The authors conclude that adjunctive ALT may improve treatment outcome and survival in patients with LTCVC-associated infections.

(Freire et al. Antimicrob Agents Chemother. 2018;62(9):e00569-18.)

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Eosinopenia as a Marker for C. difficile Severity

Reviewed by Manie Beheshti, MD

The Centers for Disease Control and Prevention highlights the immense burden of Clostridioides (formerly Clostridium) difficile infection (CDI) by citing an annual estimated incidence of nearly 500,000 infections, with 29,000 deaths, and a 9 percent 30-day mortality amongst those 65 years or older. While defining disease severity has largely been based on expert opinion, there are multiple scoring systems that may aid in identifying those at highest risk for the worst outcomes.

In a recent study published in JAMA Surgery, researchers reported on the development and validation of a predictive model for CDI mortality based on an inexpensive, ubiquitous laboratory test: the admission peripheral eosinophil count. This retrospective study analyzed a training cohort of 1,064 patients at a Pennsylvania State University medical center. Using multivariable logistic regression, an admission eosinophil count of zero was noted to be a significant predictor of mortality (odds ratio [OR]: 2.01) and morbidity (need for vasopressors, OR: 2.08; emergency total colectomy, OR: 2.56; admission to monitored care setting, OR: 1.40).

This predictive model developed based on the training cohort was then validated at the University of Virginia Health System with comparable results (mortality OR: 2.26). Interestingly, when eosinophil counts above zero were stratified to assess for a possible critical cutoff value in the subgroup analysis, only eosinophil values of zero exhibited significant associations with mortality. Further subgroup analysis of patients without tachycardia or hypotension noted a higher mortality in the zero eosinophil group (OR: 5.76) compared to those with a white blood cell count of 15,000/microliter (OR: 1.62).

Although this was a retrospective study, the research group plans on a prospective study and development of a calculable admission prognostic score to guide treatment decisions on hospital admission with the aim of decreasing mortality. A model predictive of CDI morbidity and mortality based on a simple admission eosinophil count could have enticing implications that may impact patient care, adding to the armamentarium of existing CDI scoring systems.

(Kulaylat et al. JAMA Surg. Published online: September 12, 2018.)

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