Citations

Whole-genome sequencing (WGS) is rapidly replacing traditional typing methods for the investigation of infectious disease outbreaks. Additionally, WGS data are being used to predict phenotypic antimicrobial susceptibility. Acinetobacter baumannii , which is often multidrug-resistant, is a significant culprit in outbreaks in health care settings.

Abstract Background Population-based studies of Staphylococcus aureus bacteremia (SAB) in the United States are limited. We provide a contemporary evaluation of SAB incidence in Olmsted County, Minnesota, from 2006 to 2020. Methods This was a retrospective population-based study of all adult patients with SAB residing in Olmsted County from 1 January 2006 through 31 December 2020. Initial episodes of SAB were identified using the microbiology laboratory databases at both Olmsted Medical Center and Mayo Clinic Rochester. Results Overall, 541 incident SAB cases were identified with a median age of 66.8 (interquartile range, 54.4–78.5) years, and 60.4% were male. Among these cases, 298 (56.2%) were due to methicillin-susceptible S aureus (MSSA) and 232 (43.8%) cases of methicillin-resistant S aureus (MRSA). The overall age- and sex-adjusted SAB incidence rate (IR) was 33.9 (95% confidence interval [CI], 31.0–36.8) cases/100 000 person-years (PY). Males had a higher age-adjusted IR of 46.0 (95% CI, 41.0–51.0) cases/100 000 PY compared to females (IR, 24.4 [95% CI, 21.1–27.7] cases/100 000 PY). Age- and sex-adjusted SAB IRs due to MSSA and MRSA were 18.7 and 14.6 cases/100 000 PY, respectively, and the percentage of incident SAB cases due to MRSA fluctuated across the study period. There was no apparent temporal trend in SAB incidence over the study period (P = .093). Conclusions Our investigation represents the only contemporary population-based study in the United States. Despite the impression that SAB incidence may have increased based on Centers for Disease Control and Prevention surveillance data, our finding of no change in SAB incidence was somewhat unanticipated.

Abstract Background Cardiovascular implantable electronic device (CIED) implantation has markedly increased over the past two decades. Staphylococcus aureus bacteremia (SAB) occurs in patients with CIED and determination of device infection among patients without clinical findings of pocket site infection is often difficult. Our study examines the characteristics, management, and outcomes of SAB in patients living with CIED using 2019 international criteria to define CIED infection. Methods We conducted a retrospective study of patients with CIED who were hospitalized at Mayo Clinic, Rochester, with SAB from January 1, 2012 to December 31, 2019. Patients who met CIED infection criteria following SAB based on the 2019 European Heart Rhythm Association International Concensus Document were identified. A time-to-event analysis was used to determine the impact, if any, of complete device extraction on outcomes. Results Overall, 110 patients with CIED developed SAB and 92 (83.6%) of them underwent transesophageal echocardiogram (TEE). Eighty-eight (80%) had CIED infection with 57 (51.8%) and 31 (28.2%) patients meeeting criteria for definite and possible CIED infections, respectively. Forty-three (75.4%) patients with definite CIED infection underwent complete device extraction. For possible and rejected CIED infection, the rates of complete device extraction were 35.5% and 27.3%, respectively (p< .001 for each). The primary endpoint of a composite of one-year mortality and SAB relapse had a rate that was significantly lower in patients with CIED infection who underwent complete device extraction as compared to that of patients who did not undergo device extraction (25.9% vs. 76.5%, p< .001). No significant difference in outcomes was seen in the rejected CIED infection group (33.3% vs. 62.5%, p =.27). Conclusion The rate of CIED infections following SAB was higher than that reported previously. Increased use of TEE and a novel case definition with broader diagnostic criteria were likely operative, in part, in accounting for the the higher rate of CIED infections complicating SAB. Complete device removal is critical in patients with either definite or possible CIED infection as defined by the 2019 consensus document to improve one-year mortality and SAB relapse rates. Disclosures Larry M. Baddour, MD, Boston Scientific (Individual(s) Involved: Self): Consultant; Botanix Pharmaceuticals (Individual(s) Involved: Self): Consultant; Roivant Sciences (Individual(s) Involved: Self): Consultant Muhammad R. Sohail, MD, Medtronic (Consultant)Philips (Consultant)

Abstract Background Conventional blood cultures were compared to plasma cell-free DNA–based 16S ribosomal RNA (rRNA) gene polymerase chain reaction (PCR)/next-generation sequencing (NGS) for detection and identification of potential pathogens in patients with sepsis. Methods Plasma was prospectively collected from 60 adult patients with sepsis presenting to the Mayo Clinic (Minnesota) Emergency Department from March through August 2019. Results of routine clinical blood cultures were compared to those of 16S rRNA gene NGS. Results Nineteen (32%) subjects had positive blood cultures, of which 13 yielded gram-negative bacilli, 5 gram-positive cocci, and 1 both gram-negative bacilli and gram-positive cocci. 16S rRNA gene NGS findings were concordant in 11. For the remaining 8, 16S rRNA gene NGS results yielded discordant detections (n = 5) or were negative (n = 3). Interestingly, Clostridium species were additionally detected by 16S rRNA gene NGS in 3 of the 6 subjects with gastrointestinal sources of gram-negative bacteremia and none of the 3 subjects with urinary sources of gram-negative bacteremia. In the 41 remaining subjects, 16S rRNA gene NGS detected at least 1 potentially pathogenic organism in 17. In 15, the detected microorganism clinically correlated with the patient’s syndrome. In 17 subjects with a clinically defined infectious syndrome, neither test was positive; in the remaining 7 subjects, a noninfectious cause of clinical presentation was identified. Conclusions 16S rRNA gene NGS may be useful for detecting bacteria in plasma of septic patients. In some cases of gram-negative sepsis, it may be possible to pinpoint a gastrointestinal or urinary source of sepsis based on the profile of bacteria detected in plasma.

Abstract Background Accurate microbiologic diagnosis is important for appropriate management of infectious diseases. Sequencing-based molecular diagnostics are increasingly used for precision diagnosis of infections. However, their clinical utility is unclear. Methods We conducted a retrospective analysis of specimens that underwent 16S ribosomal RNA (rRNA) gene polymerase chain reaction (PCR) followed by Sanger sequencing at our institution from April 2017 through March 2019. Results A total of 566 specimens obtained from 460 patients were studied. Patients were considered clinically infected or noninfected based on final diagnosis and management. In 17% of patients, 16S rRNA PCR/sequencing was positive and in 5% of patients, this test led to an impact on clinical care. In comparison, bacterial cultures were positive in 21% of patients. Specimens with a positive Gram stain had 12 times greater odds of having a positive molecular result than those with a negative Gram stain (95% confidence interval for odds ratio, 5.2–31.4). Overall, PCR positivity was higher in cardiovascular specimens (37%) obtained from clinically infected patients, with bacterial cultures being more likely to be positive for musculoskeletal specimens (P < .001). 16S rRNA PCR/sequencing identified a probable pathogen in 10% culture-negative specimens. Conclusion 16S rRNA PCR/sequencing can play a role in the diagnostic evaluation of patients with culture-negative infections, especially those with cardiovascular infections.

Abstract Background Infective endocarditis (IE) is the most feared complication of Staphylococcus aureus bacteremia (SAB). Transesophageal echocardiogram (TEE) is generally recommended for all patients with SAB; however, supporting data for this are limited. We previously developed a scoring system, “PREDICT,” that quantifies the risk of IE and identifies patients who would most benefit most from undergoing TEE. The current prospective investigation aims to validate this score. Methods We prospectively screened all consecutive adults (≥18 years) hospitalized with SAB at 3 Mayo Clinic sites between January 2015 and March 2017. Results Of 220 patients screened, 199 with SAB met study criteria and were included in the investigation. Of them, 23 (11.6%) patients were diagnosed with definite IE within 12 weeks of initial presentation based on modified Duke’s criteria. Using the previously derived PREDICT model, the day 1 score of ≥4 had a sensitivity of 30.4% and a specificity of 93.8%, whereas a day 5 score of ≤2 had a sensitivity and negative-predictive value of 100%. Additional factors including surgery or invasive procedure in the past 30 days, prosthetic heart valve, and higher number of positive blood culture bottles in the first set of cultures were associated with increased risk of IE independent of the day 5 risk score. Conclusions We validated the previously developed PREDICT scoring tools for stratifying risk of IE, and the need for undergoing a TEE, among cases of SAB. We also identified other factors with predictive potential, although larger prospective studies are needed to further evaluate possible enhancements to the current scoring system.

Abstract Background Stenotrophomonas maltophilia is a gram-negative, opportunistic infection that is usually hospital-acquired and associated with high morbidity and mortality. The reported increase in S. maltophilia infections is presumed to be due to an increase in the population at risk. Methods We retrospectively reviewed 10-year data for S. maltophilia bacteremia in hospitalized adults at our institution to determine the population at risk, sources of infection, common complications, antimicrobial susceptibility profiles, and clinical outcome trends over the past decade. Results Among the 98 patients analyzed, the most common source of infection was catheter-related (62, 63.3%). Most isolates (61, 65%) were resistant to ceftazidime; fewer were resistant to trimethoprim-sulfamethoxazole (TMP-SMX; 2, 2.1%) and levofloxacin (22, 23.4%). All-cause in-hospital mortality was 29.6% (29 patients). The highest mortality, 53.8%, was observed in pulmonary sources of bacteremia. Conclusions Although TMP-SMX continues to have reliable activity in our cohort, we noted resistance to TMP-SMX in patients with recent TMP-SMX exposure, including a case with developing resistance to TMP-SMX while on therapy.

AbstractBackgroundMycobacterium marinum is a common but underreported mycobacterial infection. We conducted a large retrospective study to determine risk factors and describe the therapeutic interventions and outcomes in patients with uncomplicated and complicated M. marinum infection.MethodsCulture-confirmed M. marinum infection cases were identified from the Mayo Clinic Clinical Mycology Laboratory from January 1998 to December 2018. Complicated M. marinum infection was defined as the presence of tenosynovitis, septic arthritis, or osteomyelitis. Differences in complicated vs uncomplicated M. marinum infections were analyzed using statistical comparisons.ResultsTwelve cases had a complicated M. marinum infection. Patients with a complicated infection were older (64.3 ± 11.1 vs 55.8 ± 14.5; P = .03), had longer duration of symptoms (5 vs 3 months; P = .011), and had more surgical debridements (1 vs 0; P < .001). Length of treatment and number of drugs used were not statistically significant. Complicated M. marinum cases received more medications (2 vs 1; P = .263) and were treated longer (5.7 vs 3.5 months; P = .067). Antibiotic susceptibilities were performed in 59% of the patients. All isolates were susceptible to clarithromycin. From the tetracyclines, doxycycline had a better susceptibility pattern.ConclusionsM. marinum infection is an important cause of skin and soft tissue infection. Poor water exposure documentation, unusual clinical presentation, and empiric antibiotic treatment before definitive M. marinum diagnosis often contribute to a delayed diagnosis. Complicated M. marinum cases had longer duration of symptoms and more surgical debridements. No difference in the number of drugs used or clinical outcome was observed.

Nocardia species are found worldwide and are opportunistic pathogens of both immunocompromised and immunocompetent hosts. Recent updates to the taxonomy of this genus have indicated that there are more than 90 recognized species of Nocardia with 54 species reported to be clinically relevant.

Abstract Background Ocular syphilis is an infrequent presentation of Treponema pallidum infection. It is often seen in association with neurosyphilis but can occur in isolation as well. Here we describe a case series of 10 patients with ocular syphilis seen at our institution. Methods Patients with a diagnosis of ocular syphilis at the three sites of Mayo Clinic were identified from June 2006 to February 2019. Patient’s baseline characteristics, clinical presentation, diagnostic testing, and treatment were abstracted from Electronic Medical Records. Results We identified 10 patients (17 eyes) during the study period, half being diagnosed in the last 5 years. The median age was 51 years (IQR 21–66), and the majority were males (7/10). Characteristics of the patients are outlined in Table 1. Common presenting symptoms included vision loss (8/10), photophobia (4/10), and irritation (5/10). Seven of 10 patients had bilateral involvement. Of the 17 eyes, 59% had pan-uveitis and 82% had disc edema (Table 2). Rapid Plasma Reagin (RPR) was positive in 9 patients and median serum RPR was 1:128 (IQR 1:2-1:1024). One patient was diagnosed with a positive TP-PA, and characteristic ocular findings. One patients had positive 16S Ribosomal RNA Gene PCR/Sanger Sequencing on vitreous humor specimen for Treponema species. The majority of patients had isolated ocular symptoms at presentation; two patients also had an associated skin rash. All patients underwent a lumbar puncture (LP). Half had pleocytosis (TNC > 5) and elevated protein elevated (mean 63.6 mg/dL), although not significantly high. 3/10 patients had VDRL positive in the CSF. Protein levels were much higher in those with positive VDRL. Each patient was treated with intravenous (IV) penicillin for at least 2 weeks. Nine patients received ocular steroids as well. At last available follow-up, 8 had complete and 1 had partial resolution. One had worsened eye findings with eventual scarring. Conclusion Our findings are congruent with increasing incidence of ocular syphilis nationwide. Bilateral eye involvement and pan-uveitis were the most common ocular findings. Although only 3 patients had a positive VDRL in the CSF, pleocytosis and elevated protein were found in a large number of patients. Majority of the patients had clinical resolution with appropriate treatment. Disclosures All authors: No reported disclosures.