657. Evaluating Clinical Outcomes of Bacteremic Patients Treated with AmpC-Inducing Versus -Stable Agents

Background

AmpC enzymes are β-lactamases that can rapidly hydrolyze penicillins, cephalosporins, and monobactams. When in the presence of β-lactams, inducible pathogens can become derepressed and lead to an overproduction of AmpC. Because of this induction potential, agents that appear susceptible may quickly become resistant, complicating the treatment choices for these infections. The purpose of this study is to assess clinical outcomes in bacteremic patients with an AmpC producing organism based on the antimicrobial agent used.

Methods

This retrospective chart review is approved by Northwell Health IRB and evaluated patients admitted with a positive blood culture from July 2017 to January 2022. The primary objective is outcome of infection (treatment success or failure). Secondary objectives include 30-day readmission related to infection, microbiologic relapse, and in-hospital mortality. Patients were included if they had a positive blood culture demonstrating E. cloacae, E. aerogenes, or C. freundii, cefoxitin resistance, and were treated with a β-lactam antibiotic for at least 72 hours. Patients were excluded if they had polymicrobial cultures or if a resistance gene was detected.

Results

A total of 71 patients were included in analysis, with 40 patients in the carbapenem or cefepime group (Group A), 18 patients in the piperacillin/tazobactam group (Group B), and 13 patients in the ceftriaxone or aztreonam group (Group C). The most frequently isolated pathogen was E. cloacae and the most common source of infection was genitourinary. Treatment failure was seen in 16.7% of Group B patients, 15.4% of Group C patients, and 12.5% of Group A patients (p=0.901). Microbiologic relapse was experienced in 5.6% of patients in Group B and 2.5% of patients in Group A (p=0.686). In Group C, 15.4% of patients were readmitted within 30 days related to infection, compared to 11.1% in Group B and 2.5% in the Group A (p=0.23). In-hospital mortality was 16.7% in Group B, compared to 15% in Group A (p=0.341).

Conclusion

Although not statistically significant, patients who received piperacillin/tazobactam had numerically more treatment failure, microbiologic relapse, and 30-day readmission related to infection when compared to the patients who received a carbapenem or cefepime.

Disclosures

All Authors: No reported disclosures.

Metformin Use Is Inversely Associated with Prevalent, but Not Incident Colorectal Adenomas

BACKGROUND

Chemoprevention for colorectal neoplasia has attracted growing interest, with multiple medications investigated. Metformin may decrease the overall incidence of cancer in patients with diabetes and may decrease the incidence of colorectal cancer.

AIMS

We aimed to determine the impact of metformin use on the behavior of colorectal adenomas in a US veteran population.

METHODS

All patients with at least two high-quality colonoscopies between January 1997 and December 2013 at Veterans Affairs New York Harbor Healthcare System were identified. Outpatient prescription records were used to determine metformin exposure, and colonoscopy findings were recorded. Multivariable logistic regression was used to determine factors associated with adenoma detection on baseline and interval colonoscopy.

RESULTS

In total, 1869 patients with two successive colonoscopies (median 4.5 years) were included. Four hundred and sixty patients had metformin exposure prior to baseline and/or interval colonoscopy. Overall adenoma detection rate was 59.7% at baseline and 45.9% at interval colonoscopy. On multivariable analysis, metformin use was associated with decreased adenoma prevalence at baseline (OR 0.68; 95% CI 0.51-0.92; p = 0.015). Metformin did not impact adenoma incidence at interval colonoscopy whether prescribed before baseline (OR 1.26; 95% CI 0.60-2.67), after baseline (OR 1.25; 95% CI 0.91-1.72), or before and after baseline (OR 1.14; 95% CI 0.82-1.58).

CONCLUSIONS

In this retrospective analysis of an average-risk cohort, metformin use was associated with a decreased prevalence of colorectal adenomas at baseline colonoscopy. This inverse association did not persist on interval colonoscopy. Prospective studies are needed to evaluate potential chemoprotective effects of metformin over time.

Passive transfer of SARS-CoV-2 antibodies with platelet transfusions

Background

Although over 5000 platelet transfusions occur daily in the United States, the presence of SARS‐CoV‐2 antibodies in platelet units is not commonly evaluated for. The effects of platelet transfusions with SARS‐CoV‐2 antibodies remain largely unknown. We evaluated single‐donor (apheresis) platelet units for SARS‐CoV‐2 antibodies and determined if platelet transfusions passively transferred antibodies to seronegative recipients.

Study Design and Methods

We conducted a retrospective analysis as part of a quality assurance initiative during February to March 2021 at a tertiary referral academic center in suburban New York. Platelet units and platelet recipients were evaluated for the presence of SARS‐CoV‐2 antibodies using the DiaSorin LIASON SARS‐CoV‐2 S1/S2 IgG assay. There were 47 platelet recipients eligible for study inclusion. The primary outcome was the presence of SARS‐CoV‐2 spike protein IgG antibodies in the recipient's blood after platelet transfusion.

Results

Twenty‐three patients received platelets with SARS‐CoV‐2 spike protein IgG antibodies; 13 recipients had detection of SARS‐COV‐2 antibodies (56.5%), and 10 recipients did not. The median antibody titer in the platelet units given to the group with passive antibodies detected was significantly higher compared to the median antibody titer in the platelet units given to the group without antibodies detected (median [interquartile range]: 306 AU/ml [132, 400] vs. 96.1 AU/ml [30.6, 186], p = .027).

Conclusions

Our study demonstrated a significant rate of passive transfer of SARS‐CoV‐2 spike protein IgG antibodies through platelet transfusions. Considering the volume of daily platelet transfusions, this is something all clinicians should be aware of.

Salmonella Septic Arthritis and Bacteremia in a Patient With Poorly Controlled Diabetes

Salmonella belongs to the Enterobacteriaceae family and is a frequent gastroenteritis pathogen when the food is not well handled. We present a case of indolent septic arthritis of the knee secondary to Salmonella bacteremia and uncontrolled diabetes. The knee effusion analysis showed a total nucleated cell count of 9206 cells/uL and no organism was seen under Gram stain. Both blood culture and synovial fluid culture later grew Salmonella enterica serovar Enteritidis. Meticulous workups revealed his previously undiagnosed and uncontrolled diabetes as the sole risk factor for developing severe salmonellosis. Serious non-typhoidal Salmonella infections often occur in immunocompromising states such as extreme age, HIV, malignancy, corticosteroid use, and rheumatologic disorders. Extraintestinal salmonellosis warrants surveillance for the aforementioned conditions. This case was unique in that septic arthritis and bacteremia due to Salmonella in a healthy man led to a diagnosis of uncontrolled diabetes. Like other bacterial septic arthritis, antimicrobial agents and proper drainage are the keys to treatment success. At least two weeks of antimicrobial therapy is needed for the treatment of Salmonella soft-tissue infection; however, therapy for four-six weeks might be necessary given the known persistence of Salmonella species at compromised sites.