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. 2022 Jul 22;9(7):ofac347.
doi: 10.1093/ofid/ofac347. eCollection 2022 Jul.

Impact of a Laboratory-Developed Phenotypic Rapid Susceptibility Test Directly From Positive Blood Cultures on Time to Narrowest Effective Therapy in Patients With Gram-Negative Bacteremia: A Prospective Randomized Trial

Alyssa B Christensen  1 , Brent Footer  2 , Tobias Pusch  3 , Kim Heath  4 , Maha Iqbal  4 , Lian Wang  5 , Gregory Tallman  1 , Cameron Cover  3 , Jennifer Marfori  3 , Brian Kendall  6 , Nick Stucky  6 , Meagan Greckel  1 , Ivor L Thomas  4 , Katelynn Tran  1 , Salena Yip  1 , Margret Oethinger  4
Affiliations

Impact of a Laboratory-Developed Phenotypic Rapid Susceptibility Test Directly From Positive Blood Cultures on Time to Narrowest Effective Therapy in Patients With Gram-Negative Bacteremia: A Prospective Randomized Trial

Alyssa B Christensen et al. Open Forum Infect Dis. .

Abstract

Background: Antimicrobial susceptibility testing (AST) is often needed prior to antimicrobial optimization for patients with gram-negative bloodstream infections (GN-BSIs). Rapid AST (rAST) in combination with antimicrobial stewardship (AS) may decrease time to administration of narrower antibiotics.

Methods: This was a prospective, nonblinded, randomized trial evaluating the impact of a phenotypic rAST method vs conventional AST (cAST) in hospitalized patients with GN-BSI and source control. The primary outcome was time to narrowest effective therapy.

Results: Two hundred seventy-four patients were randomized and 205 underwent analysis (97 cAST, 108 rAST). Median (interquartile range [IQR]) time to susceptibility results was 23 hours shorter in the rAST group (cAST: 62 [59-67] hours vs rAST: 39 [IQR, 35-46] hours; P < .001). Median (IQR) time to narrowest effective therapy was similar between groups (cAST: 73 [44-138] hours vs rAST: 64 [42-92] hours; P = .10). Median (IQR) time to narrowest effective therapy was significantly shorter in a prespecified subgroup of patients not initially on narrowest therapy and during AS working hours (cAST: 93 [56-154] hours vs rAST: 62 [43-164] hours; P = .004). Significant decreases were observed in median (IQR) time to oral therapy (cAST: 126 [76-209] hours vs rAST: 91 [66-154] hours; P = .02) and median (IQR) length of hospital stay (cAST: 7 [4-13] days vs rAST: 5 [4-8] days; P = .04).

Conclusions: In patients with GN-BSI, rAST did not significantly decrease time to narrowest effective therapy but did decrease time to oral antibiotics and length of hospital stay. Rapid AST using existing microbiology platforms has potential to optimize patient outcomes.

Keywords: antimicrobial stewardship; antimicrobial susceptibility testing; bloodstream infection; gram negative; rapid diagnostic testing.

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Figures

Figure 1.
Figure 1.
Participant screening and randomization. Abbreviation: AST, antimicrobial susceptibility testing.
Figure 2.
Figure 2.
Time course of patient outcomes between rapid antimicrobial susceptibility testing (rAST) and conventional antimicrobial susceptibility testing (cAST). Outcomes from the full cohort as reported in Table 2. Time points are reported as median values.
See this image and copyright information in PMC

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References

    1. Goto M, Al-Hasan MN. Overall burden of bloodstream infection and nosocomial bloodstream infection in North America and Europe. Clin Microbiol Infect 2013; 19:501–9. doi:10.1111/1469-0691.12195 - DOI - PubMed
    1. Kang C-I, Kim S-H, Kim H-B, et al. . Pseudomonas aeruginosa bacteremia: risk factors for mortality and influence of delayed receipt of effective antimicrobial therapy on clinical outcome. Clin Infect Dis 2003; 37:745–51. doi:10.1086/377200 - DOI - PubMed
    1. Kang C-I, Kim S-H, Park WB, et al. . Bloodstream infections caused by antibiotic-resistant gram-negative bacilli: risk factors for mortality and impact of inappropriate initial antimicrobial therapy on outcome. Antimicrob Agents Chemother 2005; 49:760–6. doi:10.1128/AAC.49.2.760-766.2005 - DOI - PMC - PubMed
    1. Diekema DJ, Beekmann SE, Chapin KC, Morel KA, Munson E, Doern GV. Epidemiology and outcome of nosocomial and community-onset bloodstream infection. J Clin Microbiol 2003; 41:3655–60. doi:10.1128/JCM.41.8.3655-3660.2003 - DOI - PMC - PubMed
    1. Lodise TP, Kanakamedala H, Hsu WC, Cai B. Impact of incremental delays in appropriate therapy on the outcomes of hospitalized adult patients with gram-negative bloodstream infections: “Every day matters.” Pharmacotherapy 2020; 40:889–901. - PubMed