168. Closing Time: A Quasi-experiment Comparing Time to Optimal Therapy using Traditional Identification and Susceptibility Methods, Rapid Identification, or Rapid Identification with Phenotype for Gram-negative Bloodstream Infections

Background

Bloodstream infections (BSI) are a major cause of morbidity and mortality. Compared to traditional microbiology methods, rapid diagnostic testing (RDT) provides prompt organism identification and antibiotic susceptibility results. This leads to earlier opportunities to optimize therapy, which may improve patient outcomes.

Methods

This was a single center quasi-experimental study of hospitalized adults with Gram-negative (GN) BSI, comparing the management and outcomes across three periods: pre-RDT (traditional identification and susceptibilities with BD Phoenix®, December 2014 to September 2016), RDT1 (Nanosphere Verigene®, December 2016 to December 2019), and RDT2 (Accelerate Pheno™, February 2020 to September 2021). The primary outcome was time to optimal therapy (TTOT). Secondary outcomes included time to oral antibiotic step-down, hospital length of stay (LOS), incidence of Clostridioides difficile infection, and 30-day inpatient mortality. Chi-squared and Kruskal-Wallis tests were used to compare categorical and continuous variables. Significance values for the primary endpoint were adjusted with Bonferroni correction to account for multiple pairwise comparisons.

Results

Of 296 included patients, 100 were in the pre-RDT, 98 in the RDT1, and 98 in the RDT2 arms. The most common organisms were Escherichia coli (64.5%) and Klebsiella species (20.3%). The TTOT (median, interquartile range) in the pre-RDT, RDT1, and RDT2 groups were 46 (7-61), 30 (0-53), and 12 (0-28) hours (P< 0.001), respectively. The time to oral antibiotic step-down and hospital LOS was similar between groups. There was no difference in C. difficile infection or 30-day inpatient mortality (Table 1). Table 1.

Limited Clinical Utility of Follow-up Blood Cultures in Patients With Streptococcal Bacteremia: An Opportunity for Blood Culture Stewardship

Background

The value of positive follow-up blood cultures (FUBCs) in streptococcal bacteremia has not been well defined. Therefore, we explored the frequency of and risk factors for positive FUBC in a retrospective cohort of patients with streptococcal bacteremia.

Methods

Adults ≥18 years of age, admitted with at least 1 positive blood culture for Streptococcus spp between 2013 and 2018 followed by at least 1 FUBC, were potentially eligible. Positive FUBCs were defined as cultures positive for the same streptococcal species drawn >24 hours after the index culture. We excluded patients with polymicrobial bacteremia. We compared the characteristics of patients with and without a positive FUBC.

Results

In our single-center cohort, we identified 590 patients with streptococcal bacteremia, and 314 patients met inclusion criteria. Ten patients had FUBC with Streptococcus spp (3.2%), 4 (1.3%) had a contaminant identified, and 3 (1.0%) had a new pathogen isolated. Endocarditis (5 of 10 [50.0%] vs 35 of 304 [11.5%]), epidural abscess (2 of 10 [20%] vs 4 of 304 [1.3%]), and discitis or vertebral osteomyelitis (3 of 10 [30.0%] vs 14 of 304 [4.6%]) were associated with positive FUBC. Patients with positive FUBC had a longer median length of stay (12.9 vs 7.1 days, P = .004) and longer duration of antibiotic treatment (14.9 vs 43.2 days, P = .03).

Conclusions

Follow-up blood cultures among patients with streptococcal BSI are rarely positive. Clinicians could consider limiting follow-up blood cultures in patients at low risk for deep-seated streptococcal infections, persistent bacteremia, or endovascular infection.

Antimicrobial Stewardship Programs as a Means to Optimize Antimicrobial Use

Each year, approximately 2 million people in the United States contract an infection during a hospital stay. An increasing percentage of these institutionally acquired infections are attributed to antimicrobial-resistant organisms. At the same time, studies and surveys suggest that as much as half of all antimicrobial use is inappropriate. Recommendations for preventing and reducing antimicrobial resistance in hospitals stress the importance of improving antimicrobial use, referred to as antimicrobial stewardship, at the institutional level. Antimicrobial stewardship programs have served as wake-up calls to both clinicians and health care administrators. We review the more recent literature concerning the impact of antimicrobial stewardship programs on costs, outcomes, and resistance and summarize important considerations for implementation of these programs.

Antibiotic optimization. An evaluation of patient safety and economic outcomes

BACKGROUND

Although numerous reports have described interventions designed to influence antibiotic utilization, to our knowledge none have been evaluated in a randomized study.

METHODS

Adult inpatients receiving 1 or more of 10 designated parenteral antibiotics for 3 or more days during a 3-month period were randomized to an intervention (n = 141) and a control (n = 111) group using an unblocked, computer-generated random number table. Obstetric patients and those seen in infectious disease consultation were excluded. The intervention group received antibiotic-related suggestions from a team consisting of an infectious disease fellow and a clinical pharmacist. Both groups were evaluated for clinical and microbiological outcomes as well as antibiotic utilization via prospective chart reviews and analysis of the hospital's administrative database.

RESULTS

Sixty-two (49%) of the intervention group patients received a total of 74 suggestions. Sixty-three (84%) of these suggestions were implemented; the majority involved changes in antibiotic choice, dosing regimen, or route of administration. Per patient antibiotic charges were nearly $400 less in the intervention group vs controls (P = .05). Almost all the savings were related to lower intravenous antibiotic charges. Clinical and microbiological response, antibiotic-associated toxic effects, in-hospital mortality, and readmission rates were similar for both groups. Multiple linear regression analysis identified randomization to the intervention group and female sex as the sole predictors of lower antibiotic charges. There was a trend toward a shorter length of stay for the intervention group (20 vs 24.7 days, P = .11).

CONCLUSIONS

This is the first randomized study to evaluate whether antibiotic choices can be influenced in a cost-effective fashion without sacrificing patient safety. We demonstrate that 50% of patients initially treated with expensive parenteral antibiotics can have their regimens refined after 3 days of therapy and that these modifications result in good clinical outcomes with a substantial reduction in antibiotic expense.

Intestinal capillary filtration in acute and chronic portal hypertension

The impact of acute and chronic portal hypertension on the dynamics of intestinal microvascular fluid exchange was examined in anesthetized, fasted, sham-operated control rats with normal portal pressures (CON), during acute elevations in portal pressure (APH) in control rats, and in rats in which chronic portal hypertension (CPH) was produced by calibrated stenosis of the portal vein 10 days prior to the experiments. Although intestinal blood flow and vascular resistance were not altered by APH in control rats, CPH was associated with an increased intestinal blood flow and reduced intestinal vascular resistance when compared with CON and APH. Intestinal capillary pressure and lymph flow were elevated in APH and CPH relative to control values. However, the increase in both variables was greater in CPH. The capillary filtration coefficient was elevated only in CPH. The transcapillary oncotic pressure gradient was not altered by APH or CPH. Interstitial fluid pressure was increased from -1.1 mmHg in CON to 3.9 mmHg during APH and to 5.0 mmHg in CPH. The results of this study indicate that chronic elevations in portal venous pressure produce larger increments in intestinal capillary pressure and filtration rate than do acute elevations in portal venous pressure of the same magnitude. However, the potential edemagenic effects of elevated capillary pressure in both acute and chronic portal hypertension are opposed by increases in lymph flow and interstitial fluid pressure.

Fine-morphology of chief cells in human gastric mucosa after secretin

Quantitative ultrastructural studies of human gastric mucosal chief cells during secretory stimulation have not been reported previously. In five healthy subjects we studied the effect of intravenous administration of 2 CU/kg of GIH secretin on gastric chief-cell ultrastructure. Gastric biopsies for quantitative ultrastructural analysis were obtained before and 15 and 30 min after secretin administration. Electron micrographs of 150 chief cells were analyzed by the Loud quantitative method. After secretin administration the percentage area occupied by zymogen granules decreased significantly at 15 and 30 min. At corresponding times membrane profile concentration (rough endoplasmic reticulum) increased significantly over basal values. This study provides morphological evidence of increased activity of chief cells after secretin administration.