Recurrence of Gram-negative Bacterial Blood Stream Infections due to relapse not reinfection

A recent investigation has revealed that relapse was the most common cause of recurrent Gram-negative bacteria bloodstream infections (GNB-BSI). The study was published in the journal, "Clinical Infectious Diseases."  

As there is not much understanding of the causes and clinical characteristics of recurrent gram-negative bacterial bloodstream infections (GNB-BSI), researchers from the U.S.A. conducted a study to understand the recurrence pattern of the GNB-BSI. A prospective study was conducted on patients with GNB-BSI to identify clinical characteristics, microbiology, and risk factors associated with these recurrent infections. Bacterial genotyping which included both pulsed-field gel electrophoresis [PFGE] and whole genome sequencing [WGS] was used to define whether these episodes were due to relapse or reinfection. Multivariable logistic regression was used to identify risk factors associated with recurrence. 

Results: 

1423 patients with GNB-BSI met the criteria for inclusion in this study. 

Of these 60 (4%) had recurrent GNB-BSI.

Non-white race, admission to a surgical service, and presence of an indwelling cardiac device were associated with increased risk for recurrent GNB-BSI.

63% were due to relapse (30/48) and 38% were due to reinfection (18/48) based on WGS, among the 48 patients with recurrent GNB-BSI whose paired bloodstream isolates underwent genotyping, 

PFGE correctly differentiated relapse and reinfection in 98% (47/48) of cases compared with WGS.

The median time to relapse and reinfection was similar (113 days vs. 174 days).

The presence of a cardiac device was associated with relapse. 

Thus, the researchers concluded that relapse was the most common cause of recurrent GNB-BSI, and the presence of a cardiac device was a risk factor for relapse. They also found that PFGE was more accurate in differentiating relapse from reinfection when compared with WGS. 

To read the full article, click here: https://doi.org/10.1093/cid/ciac638

 Bock A, Hanson BM, Ruffin F, et al. Clinical and Molecular Analysis of Recurrent Gram-Negative Bloodstream Infections [published online ahead of print, 2022 Aug 5]. Clin Infect Dis. 2022;ciac638.