Phylogenomics of Leptospira santarosai, a prevalent pathogenic species in the Americas.

BACKGROUND: Leptospirosis is a complex zoonotic disease mostly caused by a group of eight pathogenic species (L. interrogans, L. borgpetersenii, L. kirschneri, L. mayottensis, L. noguchii, L. santarosai, L. weilii, L. alexanderi), with a wide spectrum of animal reservoirs and patient outcomes. Leptospira interrogans is considered as the leading causative agent of leptospirosis worldwide and it is the most studied species. However, the genomic features and phylogeography of other Leptospira pathogenic species remain to be determined. METHODOLOGY/PRINCIPAL FINDINGS: Here we investigated the genome diversity of the main pathogenic Leptospira species based on a collection of 914 genomes from strains isolated around the world. Genome analyses revealed species-specific genome size and GC content, and an open pangenome in the pathogenic species, except for L. mayottensis. Taking advantage of a new set of genomes of L. santarosai strains isolated from patients in Costa Rica, we took a closer look at this species. L. santarosai strains are largely distributed in America, including the Caribbean islands, with over 96% of the available genomes originating from this continent. Phylogenetic analysis showed high genetic diversity within L. santarosai, and the clonal groups identified by cgMLST were strongly associated with geographical areas. Serotype identification based on serogrouping and/or analysis of the O-antigen biosynthesis gene loci further confirmed the great diversity of strains within the species. CONCLUSIONS/SIGNIFICANCE: In conclusion, we report a comprehensive genome analysis of pathogenic Leptospira species with a focus on L. santarosai. Our study sheds new light onto the genomic diversity, evolutionary history, and epidemiology of leptospirosis in America and globally. Our findings also expand our knowledge of the genes driving O-antigen diversity. In addition, our work provides a framework for understanding the virulence and spread of L. santarosai and for improving its surveillance in both humans and animals.

Haemophilus influenzae type b invasive infections in children hospitalized between 2000 and 2017 in a Pediatric Reference Hospital (PRH).

BACKGROUND: Uruguay incorporated the conjugate vaccine against Haemophilus influenzae b (Hib) in 1994. In 2008, the vaccine was changed from one with natural conjugated capsular polysaccharide to one with a synthetic polysaccharide component. We describe the frequency and characteristics of invasive Hib infections in children hospitalized in a Pediatric Reference Hospital (PRH) between January 1st, 2000 and December 31st, 2017. METHODS: Sterile site Hib isolations from hospitalized children were included. Clinical and microbiological characteristics were analyzed. Favorable conditions for the infection were considered: incomplete immunization, immunodeficiencies and associated pathologies. Two periods are described: 1, prior to vaccine change (1/1 st/2000- 12/31/08) and 2, post-change (1/1 st/09- 12/31st/17). RESULTS: 45 children were hospitalized: 5 in the first period and 40 in the second. The hospitalization rate per 10,000 discharges was 0.41 (95% CI 0.05-0.77) and 4.2/10,000 (95% CI 2.89-5.48), respectively (p < 0.01). The diagnoses at discharge were: meningitis/ventriculitis (20), pneumonia (16), bacteremia (3), epiglottitis (1), arthritis (1), cellulitis (3) and obstruction of the upper airway (1). Four children presented comorbidities. Twenty seven received less than 3 doses of anti-Hib vaccination and 18 were properly vaccinated (2 were immunodeficient). The median hospitalization was 14 days, 18 children required intensive therapy. CONCLUSIONS: Observed change may be due to: incomplete primary series, inhomogeneous vaccine coverage and immunogenicity of the synthetic polysaccharide. To reduce this public health problem, epidemiological surveillance.

Draft Genome Sequences of 40 Pathogenic Leptospira Strains Isolated from Cattle in Uruguay.

Pathogenic Leptospira species represent a major concern for livestock but also for human health, as they cause zoonotic infections. Forty strains representing L. interrogans, L. borgpetersenii, and L. noguchii were isolated from naturally infected cattle in Uruguay. Here, we report the whole-genome sequences for these strains.

Leptospira interrogans serogroup Pomona serovar Kennewicki infection in two sheep flocks with acute leptospirosis in Uruguay.

Acute leptospirosis is an infrequent disease in sheep that can cause jaundice, haemolysis, haemoglobinuria, hepatitis and nephritis. In most reports the diagnoses have been made by clinical, pathological or serological evidence without isolation or direct identification of the agent. Here, we report one confirmed and one presumptive outbreak of acute leptospirosis in suckling lambs from two unrelated sheep farms in Uruguay with mortalities of 9/60 (15%) and 9/163 (5.5%) lambs. Both outbreaks occurred in Sep-Oct 2017 after heavy rainfall and flooding events. The main gross and histologic pathological findings in two autopsied lambs, one from each farm, included severe diffuse jaundice, haemoglobinuria, acute necrotizing hepatitis with cholestasis and interstitial nephritis. Leptospira interrogans serogroup Pomona serovar Kennewicki was isolated from sheep in both flocks and the same genotype was identified directly in clinical samples from infected animals, including one of the deceased lambs subjected to autopsy, by amplification and partial sequencing of rrs and secY genes. This serovar has recently been identified in infected cattle and humans in Uruguay. The impact of Leptospira spp. infection in ovine health, and the epidemiologic role of sheep as reservoirs of leptospirosis for humans and animals need further investigation.

Isolation of pathogenic Leptospira strains from naturally infected cattle in Uruguay reveals high serovar diversity, and uncovers a relevant risk for human leptospirosis.

Leptospirosis is a neglected zoonosis with worldwide distribution. The causative agents are spirochete bacteria of the Leptospira genus, displaying huge diversity of serovars, the identity of which is critical for effective diagnosis and vaccination purposes. Among many other mammalian species, Leptospira infects cattle, eliciting acute signs in calves, and chronic disease in adult animals often leading to abortions. In South America, and including in Uruguay, beef and dairy export are leading sources of national income. Despite the importance of bovine health, food safety, and bovine-related dissemination of leptospirosis to humans, extremely limited information is available as to the identity of Leptospira species and serovars infecting cattle in Uruguay and the South American subcontinent. Here we report a multicentric 3-year study resulting in the isolation and detailed characterization of 40 strains of Leptospira spp. obtained from infected cattle. Combined serologic and molecular typing identified these isolates as L. interrogans serogroup Pomona serovar Kennewicki (20 strains), L. interrogans serogroup Canicola serovar Canicola (1 strain), L. borgpetersenii serogroup Sejroe serovar Hardjo (10 strains) and L. noguchii (9 strains). The latter showed remarkable phenotypic and genetic variability, belonging to 6 distinct serogroups, including 3 that did not react with a large panel of reference serogrouping antisera. Approximately 20% of cattle sampled in the field were found to be shedding pathogenic Leptospira in their urine, uncovering a threat for public health that is being largely neglected. The two L. interrogans serovars that we isolated from cattle displayed identical genetic signatures to those of human isolates that had previously been obtained from leptospirosis patients. This report of local Leptospira strains shall improve diagnostic tools and the understanding of leptospirosis epidemiology in South America. These strains could also be used as new components within bacterin vaccines to protect against the pathogenic Leptospira strains that are actually circulating, a direct measure to reduce the risk of human leptospirosis.

String test: A new tool for tuberculosis diagnosis and drug-resistance detection in children.

Background: There is a critical need to improve the diagnostic accuracy of tuberculosis (TB) in children. Several techniques have been developed to improve the quality of sputum samples; however, these procedures are very unpleasant and invasive and require hospitalization and trained personnel. This study aims to explore the potential use of a new and noninvasive tool, "string test," for TB diagnosis in children and in adults not able to render sputum samples and at risk of developing multidrug-resistant TB (MDR-TB). Methods: Children with clinical suspicion of TB attending the pediatric consultation at the Cetrangolo or Cordero Hospitals and adults suspected of MDR-TB and unable to produce sputum attending the Infectious Disease Unit of Cetrangolo Hospital were included in this study. Subjects and Methods: The "string test" is a string that is swallowed by the patients and exposed to gastrointestinal secretions that were late analyzed for TB diagnosis and drug-resistance detection by GenoType MTBDRplus. MedCalc software was used to perform statistical analysis. Results: This technique could be applied on 62.1% of selected children. About 11 (30.6%) children were diagnosed as TB cases, 8 (22.2%) from gastric aspirate and using the "string test." Six out of 19 adults were also diagnosed. Genotype directly on the string specimen detected two MDR-TB in adults and two isoniazid-resistant cases before obtaining the isolate. Conclusion: This test was safe, cheap, and easily implemented without requiring hospitalization. This research could represent a significant step forward to diagnose and rapidly detect drug-resistant TB in children.

Catalytic Thr or Ser Residue Modulates Structural Switches in 2-Cys Peroxiredoxin by Distinct Mechanisms.

Typical 2-Cys Peroxiredoxins (2-Cys Prxs) reduce hydroperoxides with extraordinary rates due to an active site composed of a catalytic triad, containing a peroxidatic cysteine (CP), an Arg, and a Thr (or Ser). 2-Cys Prx are involved in processes such as cancer; neurodegeneration and host-pathogen interactions. During catalysis, 2-Cys Prxs switch between decamers and dimers. Analysis of 2-Cys Prx structures in the fully folded (but not locally unfolded) form revealed a highly conserved, non-conventional hydrogen bond (CH-π) between the catalytic triad Thr of a dimer with an aromatic residue of an adjacent dimer. In contrast, structures of 2-Cys Prxs with a Ser in place of the Thr do not display this CH-π bond. Chromatographic and structural data indicate that the Thr (but not Ser) destabilizes the decamer structure in the oxidized state probably through steric hindrance. As a general trend, mutations in a yeast 2-Cys Prx (Tsa1) favoring the dimeric state also displayed a decreased catalytic activity. Remarkably, yeast naturally contains Thr-Ser variants (Tsa1 and Tsa2, respectively) with distinct oligomeric stabilities in their disulfide states.