Leptospirosis (caused by pathogenic bacteria in the genus Leptospira) is prevalent worldwide but more common in tropical and subtropical regions. Transmission can occur following direct exposure to infected urine from reservoir hosts, or a urine-contaminated environment, which then can serve as an infection source for additional rats and other mammals, including humans. The brown rat, Rattus norvegicus, is an important reservoir of Leptospira spp. in urban settings. We investigated the presence of Leptospira spp. among brown rats in Boston, Massachusetts and hypothesized that rat population dynamics in this urban setting influence the transportation, persistence, and diversity of Leptospira spp. We analyzed DNA from 328 rat kidney samples collected from 17 sites in Boston over a seven-year period (2016-2022); 59 rats representing 12 of 17 sites were positive for Leptospira spp. We used 21 neutral microsatellite loci to genotype 311 rats and utilized the resulting data to investigate genetic connectivity among sampling sites. We generated whole genome sequences for 28 Leptospira spp. isolates obtained from frozen and fresh tissue from some of the 59 positive rat kidneys. When isolates were not obtained, we attempted genomic DNA capture and enrichment, which yielded 14 additional Leptospira spp. genomes from rats. We also generated an enriched Leptospira spp. genome from a 2018 human case in Boston. We found evidence of high genetic structure among rat populations that is likely influenced by major roads and/or other dispersal barriers, resulting in distinct rat population groups within the city; at certain sites these groups persisted for multiple years. We identified multiple distinct phylogenetic clades of L. interrogans among rats that were tightly linked to distinct rat populations. This pattern suggests L. interrogans persists in local rat populations and its transportation is influenced by rat population dynamics. Finally, our genomic analyses of the Leptospira spp. detected in the 2018 human leptospirosis case in Boston suggests a link to rats as the source. These findings will be useful for guiding rat control and human leptospirosis mitigation efforts in this and other similar urban settings.

BACKGROUND: We investigated hospitalized carbapenem-resistant Enterobacterales (CRE) and extended-spectrum β-lactamase-producing Enterobacterales (ESBL-E) cases with and without COVID-19, as identified through Emerging Infections Program surveillance in 10 sites from 2020 to 2022. METHODS: We defined a CRE case as the first isolation of Escherichia coli, Enterobacter cloacae complex, Klebsiella aerogenes, K oxytoca, K pneumoniae, or K variicola resistant to any carbapenem. We defined an ESBL-E case as the first isolation of E coli, K pneumoniae, or K oxytoca resistant to any third-generation cephalosporin and nonresistant to all carbapenems tested. Specimens were drawn from a normally sterile site or urine among hospitalized residents of the surveillance area in a 30-day period. We defined COVID-19 as a positive SARS-CoV-2 test result (SC2(+)) within 14 days before CRE or ESBL-E specimen collection and performed multivariable logistic regression analyses. RESULTS: Of 1595 CRE and 1866 ESBL-E hospitalized cases, 38 (2.4%) and 60 (3.2%), respectively, had a SC2(+). Among these cases, a SC2(+) was associated with intensive care unit admission (adjusted odds ratio [aOR], 1.69 [95% CI, 1.14-2.50]; aOR, 1.48 [95% CI, 1.03-2.12]) and 30-day mortality (aOR, 1.79 [95% CI, 1.22-2.64]; aOR, 1.94 [95% CI, 1.39-2.70]). CONCLUSIONS: CRE and ESBL-E infections among hospitalized patients with preceding COVID-19 were uncommon but had worse outcomes when compared with cases without COVID-19. COVID-19 prevention in patients at risk of CRE and ESBL-E infections is needed, as well as continued infection control measures and antibiotic stewardship for patients with COVID-19.

BACKGROUND: We described changes in 2016─2020 carbapenem-resistant Enterobacterales (CRE) incidence rates in 7 US sites that conduct population-based CRE surveillance. METHODS: An incident CRE case was defined as the first isolation of Escherichia coli, Klebsiella spp., or Enterobacter spp. resistant to ≥1 carbapenem from a sterile site or urine in a surveillance area resident in a 30-day period. We reviewed medical records and classified cases as hospital-onset (HO), healthcare-associated community-onset (HACO), or community-associated (CA) CRE based on healthcare exposures and location of disease onset. We calculated incidence rates using census data. We used Poisson mixed effects regression models to perform 2016─2020 trend analyses, adjusting for sex, race/ethnicity, and age. We compared adjusted incidence rates between 2016 and subsequent years using incidence rate ratios (RRs) and 95% confidence intervals (CIs). RESULTS: Of 4996 CRE cases, 62% were HACO, 21% CA, and 14% HO. The crude CRE incidence rate per 100 000 was 7.51 in 2016 and 6.08 in 2020 and was highest for HACO, followed by CA and HO. From 2016 to 2020, the adjusted overall CRE incidence rate decreased by 24% (RR, 0.76 [95% CI, .70-.83]). Significant decreases in incidence rates in 2020 were seen for HACO (RR, 0.75 [95% CI, .67-.84]) and CA (0.75 [.61-.92]) but not for HO CRE. CONCLUSIONS: Adjusted CRE incidence rates declined from 2016 to 2020, but changes over time varied by epidemiologic class. Continued surveillance and effective control strategies are needed to prevent CRE in all settings.