Campioli, Cristina Corsini

Abstract Background Follow-up blood cultures (FUBCs) for streptococcal bacteremia are infrequently positive and may not provide sufficient clinical impact to justify the time and resources expended for their routine use. We aimed to evaluate the frequency of and risk factors for positive FUBCs in patients with streptococcal bacteremia and to compare clinical outcomes among patients with or without positive FUBCs. Methods We retrospectively reviewed hospitalized patients with streptococcal bacteremia from September 2023 to June 2024 within a multisite health system. Patients ≥18 years old with ≥1 positive blood culture for a Streptococcus species were included. Patients with polymicrobial bacteremia, those who died or were discharged to hospice within 48 hours of their index culture, and Minnesota residents who declined research authorization were excluded. Results We included 454 patients, with 48 (10.6%) having positive FUBCs. The rate of positivity ranged from 0% for Streptococcus pyogenes to 18.5% for Streptococcus anginosus. Endocarditis and osteomyelitis were more common in the positive than in the negative FUBC group (22.9% vs 12.1%, respectively, for endocarditis [P = .04] and 16.7% vs 5.4% [P = .005] for osteomyelitis). Positive FUBCs were associated with a higher incidence of infection relapse (8.5% vs 2.7%; P = .047) and longer duration of antibiotics (30 vs 16 days; P = .01), but no differences in mortality rate, length of stay, or infection-related readmission were observed. Conclusions Positive FUBCs were infrequent for S pyogenes, Streptococcus agalactiae, Streptococcus pneumoniae, and group C and G streptococci. It may be reasonable to forego FUBC for these streptococcal species if endocarditis or osteomyelitis are not clinically suspected.

Abstract Patent foramen ovale (PFO) has a prevalence of approximately 25%. Its association with pyogenic brain abscess (PBA) is unclear. We reviewed adults with PBA and known PFO status from 1 January 2009 through 31 December 2021 at Mayo Clinic. High PFO prevalence (40.5%) was seen. PBA patients with PFO had distinct abscess characteristics but unchanged 1-year, all-cause mortality.

Abstract Background Patent foramen ovale (PFO) can be identified in about 20-25% of the adult population and may result in variable degrees of left-to-right and right-to-left intracardiac shunting. The association between PFO and pyogenic brain abscess remains poorly understood. The current study aimed to compare the clinical characteristics and outcomes of pyogenic brain abscess in patients with and without PFO. Methods All adults with pyogenic brain abscess seen at Mayo Clinic from 1/1/2009-12/31/2021 who underwent either transesophageal echocardiography (TEE) or transthoracic echocardiography (TTE) with agitated saline shunt (bubble) study were included. Results A total of 222 patients developed pyogenic brain abscess during the study period; 148 (66.7%) patients were excluded due to unknown PFO status. Among 74 remaining patients, PFO was detected in 30 (40.5%) patients; 25 by TEE and 5 by TTE with bubble study (Figure 1). The prevalence of cryptogenic brain abscess (unable to identify the source of abscess) was significantly higher in patients with PFO as compared to those without PFO (53.3% versus 18.2%, p=0.002). Patients with PFO had a larger abscess size (25 mm [IQR 15.8-37.5] versus 15.5 mm [IQR 10.0-28.0], p=0.038). However, multiple abscesses were more common in the group without PFO (43.2% versus 20.0%, p=0.038). Additionally, patients with PFO had less documented bloodstream infection. There were no differences between other clinical characteristics and one-year, all-cause mortality between two groups. Conclusion These findings provide critical insights into the likely association between PFO and cryptogenic brain abscess; additional investigation is warranted. Disclosures Larry M. Baddour, MD, Boston Scientific: Advisor/Consultant|Roivant Sciences: Advisor/Consultant

Abstract Background Deep brain stimulator (DBS)–related infection is a recognized complication that may significantly alter the course of DBS therapy. We describe the Mayo Clinic Rochester experience with DBS-related infections. Methods This was a retrospective study of all adults (≥18 years old) who underwent DBS-related procedures between 2000 and 2020 at the Mayo Clinic Rochester. Results There were 1087 patients who underwent 1896 procedures. Infection occurred in 57/1112 (5%) primary DBS implantations and 16/784 (2%) revision surgeries. The median time to infection (interquartile range) was 2.1 (0.9–6.9) months. The odds of infection were higher with longer operative length (P = .002), higher body mass index (BMI; P = .006), male sex (P = .041), and diabetes mellitus (P = .002). The association between infection and higher BMI (P = .002), male sex (P = .016), and diabetes mellitus (P = .003) remained significant in a subgroup analysis of primary implantations but not revision surgeries. Infection was superficial in 17 (23%) and deep in 56 (77%) cases. Commonly identified pathogens were Staphylococcus aureus (65%), coagulase-negative staphylococci (43%), and Cutibacterium acnes (45%). Three device management approaches were identified: 39 (53%) had complete device explantation, 20 (27%) had surgical intervention with device retention, and 14 (19%) had medical management alone. Treatment failure occurred in 16 (23%) patients. Time-to-event analysis showed fewer treatment failures with complete device explantation (P = .015). Only 1 individual had complications with brain abscess at failure. Conclusions Primary DBS implantations had higher rates of infection compared with revision surgeries. Complete device explantation was favored for deep infections. However, device salvage was commonly attempted and is a reasonable approach in select cases given the low rate of complications.

Abstract Although there is a lack of data in trimethoprim-sulfamethoxazole (TMP-SMX) serum monitoring utility for invasive nocardial infections, therapeutic drug monitoring is widely used to optimize dosing and avoid adverse reactions that may cause treatment interruption. We retrospectively reviewed all adults who received TMP-SMX to treat nocardial brain abscess and had SMX serum level testing from 2010 to 2020. Twenty-two patients received treatment with TMP-SMX for Nocardia species brain abscess and 16 (72.7%) had a reported SMX level, with a median patient age of 65.5 years (interquartile range, IQR 59.5–72.5). Compared to those who did not have a documented SMX serum level, patients with SMX levels had a shorter median course of TMP-SMX treatment (322 days [IQR 188–365] vs. 365 [IQR 224–365]; P = .31) and higher therapeutic induction dose (10 [62.5%] vs. 3 [50%]; P = .92). Similarly, they were more frequently on hemodialysis (3 [13.6%] vs. 1 [4.5%]; P = > .99). The median peak level was 158.5 (IQR 120–218) μg/mL, collected at 2 hours (75%) post-administration in the induction phase (81.3%). Patients with documented SMX levels had fewer reported drug toxicity (5 [31.3%] vs. 4 [66.7%]; P = .1) than those without SMX levels. Among the five patients who reported TMP-SMX-related toxicity, 4 (80%) had an SMX peak level >150 μg/mL. There was no difference in the cure, relapse, and death rates among the two groups. While SMX level was not associated with Nocardia species brain abscess cure rates and mortality, most patients with SMX peak >150 μg/mL experienced drug toxicity.

Abstract Clinical significance of a single positive blood culture bottle (SPBCB) with Staphylococcus aureus is unclear. We aimed to assess the significance of an SPBCB by looking at the associated outcomes. We performed a retrospective, multicenter study of patients with an SPBCB with S aureus using data collected from both electronic health records and the clinical microbiology laboratory. Overall, 534 patients with S aureus bacteremia were identified and 118 (22.1%) had an SPBCB. Among cases with an SPBCB, 106 (89.8%) were classified as clinically significant whereas 12 (10.2%) were considered contaminated or of unclear significance. A majority (92.4%) of patients received antibiotic therapy, but patients with clinically significant bacteremia were treated with longer courses (25.9 vs 5.7 days, P < .001). Significant differences in both frequency of echocardiography (65.1% vs 84.6%, P < .001) and infective endocarditis diagnosis (3.8% vs 14.2%, P = .002) were seen in those with an SPBCB compared to those with multiple positive bottles. A longer hospital length of stay and higher 90-day, 6-month, and 1-year mortality rates were seen in patients with multiple positive blood culture bottles. An SPBCB with S aureus was common among our patients. While this syndrome has a more favorable prognosis as compared to those with multiple positive blood cultures, clinicians should remain concerned as it portends a risk of infective endocarditis and mortality.

Abstract Background We describe and compare the clinical, diagnostic evaluation and outcomes of patients who underwent therapeutic management for pyogenic brain abscess. Methods We retrospectively reviewed adults who presented with pyogenic brain abscess from January 1, 2009 through June 30, 2020. Results 231 patients were identified during the study period. Sixty-one (26.4%) patients received antibiotic therapy alone, and 170 (73.6%) had a combination of antibiotic therapy and surgical intervention. The median age for the medical and combined therapy group was 59 years and 58 years, respectively. Patients who received medical treatment had a higher prevalence of infective endocarditis than those who received combined therapy (6.6% vs. 0.6%; P=0.005). The medical therapy group was more likely to have brain MRI and cranial CT than the patients with combined therapy (75.4% vs. 63.5%; P=0.041). Midline shift (11.5% vs. 31.2%; P=0.002), a single (21% vs. 83%; P=0.001) and greater size (1.4 cm vs. 2.5 cm; P=0.007) brain abscess was significant when comparing medical vs. surgically managed abscess. Stereotactic surgical technique was the preferred diagnostic approach for the medical group (65.6% vs. 46.5%; P=0.010), and excision/craniotomy for the combined group (31.1% vs. 53.5%; P=0.002). Streptococcus viridans group was the predominant organism (32.8% and 25.9%; P=0.30). Compared to those who received combined therapy, patients with medical therapy alone were most likely to receive cephalosporin (72.1% vs. 41.2%; P=< 0.0001), vancomycin (23% vs. 12.4%; P=0.047) and metronidazole (27.9% vs. 14.7%; P=0.022). In both groups, median duration of antimicrobial therapy was 42 days (P=0.12). Patients with medical therapy alone had a higher mortality rate (18% vs. 7.1%; p=0.014) but less neurologic sequelae (21.3% vs. 30.6%; P=0.16) compared with combined therapy. Medical Management. Organism isolated in the medical management group Combined Management. Organism isolated in the combined management group Demographic and Clinical Characteristics of Patients with Brain Abscess who Underwent Therapeutic Management Conclusion Most patients with pyogenic brain abscess had no identified risk factors, and brain MRI and cranial CT were the diagnostic imaging modalities of choice. Compared to those who received medical therapy alone, patients with combined treatment had a single and greater size fluid collection with the presence of midline shift. A prompt combined surgical and medical approach with prolonged antimicrobial therapy can cure the infection. Outcomes of Patients with Bacterial Brain Abscess Radiologic and Surgical Diagnosis of Patient with Brain Abscess who Underwent Therapeutic Management Disclosures John C. O’Horo, Sr., MD, MPH, Bates College and Elsevier Inc (Consultant) M. Rizwan Sohail, MD, Medtronic Inc., Philips, and Aziyo Biologics, Inc (Consultant) M. Rizwan Sohail, MD, Aziyo Biologics (Individual(s) Involved: Self): Consultant; Philips (Individual(s) Involved: Self): Consultant

Abstract Background Although trimethoprim-sulfamethoxazole (TMP-SMX) has consistently demonstrated significant interindividual variability, therapeutic drug monitoring is used to optimize dosing and avoid adverse reactions that may contribute to treatment interruption. While data exists on the use of SMX level monitoring in pneumocystis, there is a lack of data in SMX serum monitoring utility for invasive Nocardia infections. Methods We retrospectively reviewed adults who received TMP-SMX to treat nocardial brain abscess (BA) and underwent SMX testing level from January 2010 to December 2020. Results Overall, 24 patients had Nocardia spp. BA; Twenty-two (91.7%) were treated with TMP-SMX, and 16/22 (72.7%) had a documented SMX serum level. The median age was 64 (IQR 58-69) years, and the majority were males (77.3%). Compared to those who did not have a documented SMX serum level, patients with SMX levels had a higher prevalence of hemodialysis (HD, 42.9% vs. 33%; P=.99) and malignancy (50% vs. 33.3%; P=.65). The most common BA location was the frontal lobe (43.8% vs. 33.3%; P=.99), with a single (68.8% vs. 50%; P=.62) and smaller (1.3 vs. 1.9 cm; P=.58) brain fluid collection, and with fewer midline shift (6.3% vs. 16.7%; P=.48), respectively. The median TMP-SMX duration was 350 days (P=.31). The most common dosing was 2-double strength, three times a day (31.8%). The SMX median level was 158.5 (IQR 120-218) mcg/mL, collected at two hours (75%) post-administration in the induction phase (81.3%). The most common recommendation was to continue therapy based on the level results. Eleven (46%) patients had a level >150 mcg/mL, and 5 (45.5%) reported drug toxicity, including nausea in 3, acute kidney injury in 2, and thrombocytopenia in 2 patients. Ninety-four percent of the patients with SMX levels had surgical intervention for therapeutic purposes vs. 83% of those without it (P=.65). A total of 11 (50%) patients were cured, 3 (18.8%) relapsed, and 2 (12.5%) died. Conclusion Patients with SMX serum level monitoring are more likely to be on HD, during the induction phase and among those with higher and more frequent dosing. About half of patients with SMX levels >150 mcg/mL experienced drug toxicity; however, SMX levels did not impact patient outcome and length of treatment. Disclosures All Authors: No reported disclosures