Search

Group B Streptococcus (GBS) is a major human and animal pathogen that threatens public health and food security. Spill-over and spill-back between host species is possible due to adaptation and amplification of GBS in new niches but the evolutionary and functional mechanisms underpinning those phenomena are poorly known. Based on analysis of 1,254 curated genomes from all major GBS host species and six continents, we found that the global GBS population comprises host-generalist, host-adapted and host-restricted sublineages, which are found across host groups, preferentially within one host group, or exclusively within one host group, respectively, and show distinct levels of recombination. Strikingly, the association of GBS genomes with the three major host groups (humans, cattle, fish) is driven by a single accessory gene cluster per host, regardless of sublineage or the breadth of host spectrum. Moreover, those gene clusters are shared with other streptococcal species occupying the same niche and are functionally relevant for host tropism. Our findings demonstrate (1) the heterogeneity of genome plasticity within a bacterial species of public health importance, enabling the identification of high-risk clones; (2) the contribution of inter-species gene transmission to the evolution of GBS; and (3) the importance of considering the role of animal hosts, and the accessory gene pool associated with their microbiota, in the evolution of multi-host bacterial pathogens. Collectively, these phenomena may explain the adaptation and clonal expansion of GBS in animal reservoirs and the risk of spill-over and spill-back between animals and humans. Author summary: Group B Streptococcus (GBS) is a bacterium that represents a health and food security threat in three major host groups: humans (in particular neonates), bovines, and fishes. However, the genomic mechanisms driving adaptation to these hosts remain unclear. Here, we use powerful statistical approaches to compare genomes of GBS from around the world. We found that GBS' ability to exchange genes is a good indicator of how well it can adapt to different hosts. Additionally, three groups of genes appear crucial for GBS to infect either humans, cows, or fishes, regardless of the bacterial strain. These gene groups are also found in other similar bacteria that live in the same hosts or environments. Where a functional role is already known for two gene groups in humans and bovines, respectively, it is shown here for the first time for the third gene group in fishes. Our findings demonstrate the importance of considering the role of animals in the evolution of multi-host bacterial pathogens like GBS. Gene exchange between bacteria infecting multiple hosts represents a high threat to human health, as high-risk types of GBS could adapt and expand in animals, which could then act as reservoirs for highly pathogenic human infections. [ABSTRACT FROM AUTHOR]

Group B Streptococcus sequence type 103 is known primarily as a bovine mastitis pathogen. In Brazil, it has circulated in cattle and humans since the 1990s. It lacks scpB and, in humans, was found only among carriage isolates. Bovine-human interspecies transmission may have contributed to its evolution and spread. [ABSTRACT FROM AUTHOR]

In this study, we report the first isolation of Hanseniaspora opuntiae obtained from four pregnant women in Brazil. Clinical isolates were obtained from four samples taken between 35 and 37 gestational weeks, as part of the routine antenatal care for maternal colonization screening for Streptococcus agalactiae group B. The patients were immunocompetent, with two of them diagnosed with gestational diabetes mellitus. Species identification was performed by MALDI-TOF MS and rDNA sequencing. While Hanseniaspora species have not traditionally been considered a typical opportunist pathogen, our findings emphasize the importance of investigating and screening for Hanseniaspora in pregnant populations, highlighting H. opuntiae as a potential agent of human infections. [ABSTRACT FROM AUTHOR]

Background: Streptococcus pneumoniae (S. pneumoniae) of serogroup 19 are mainly represented by serotypes 19A and 19F, which are associated with antimicrobial resistance and disease. The wzy gene, a component of the pneumococcal capsular locus, is the target to differentiate serotypes 19A and 19F by PCR-based capsular typing. In the last decade, allelic variants of the wzy 19F gene have been described, leading to misinterpretation of capsular typing results., Methods: A collection of 154 serotype 19F S. pneumoniae strains recovered from carriage and disease in Brazil was evaluated to identify and characterize wzy 19F variant isolates., Results: Eleven (7%) wzy 19F variant isolates were detected and identified as belonging to ST810 (n = 10) or ST13673 (n = 1; single-locus variant of ST810). They were mostly recovered from diseased patients, susceptible to the antimicrobial agents tested (except for one multidrug-resistant strain) and did not harbor pili genes. Sequences of the wzy 19F gene of these variants were identical to each other and to those previously described in Brazil, but slightly different from wzy 19F variants identified in other countries., Conclusion: This study indicated that wzy 19F variants present a geographically driven distribution and was the first to uncover phenotypic and genetic features of a wzy 19F variant lineage occurring in Brazil since 1989., (Copyright © 2021 The Authors. Published by Elsevier Ltd.. All rights reserved.)

S. schleiferi is one of the main species isolated from canine otitis externa, pyoderma and from apparently healthy dogs. The species is divided into two subspecies, S. schleiferi schleiferi and S. schleiferi coagulans. MALDI-TOF MS does not distinguish correctly these two subspecies. This study aimed to identify biomarkers that could possibly discriminate Staphylococcus schleiferi subspecies by MALDI-TOF MS. Twelve strains (eight S. schleiferi schleiferi and four S. schleiferi coagulans) were firstly identified. Each isolate was submitted to a protein extraction protocol and subjected to spectrometry on Bruker Microflex LT mass spectrometer. Spectra were analyzed with the BioNumerics software v7.6. Our results showed that spectra clustered according to subspecies, and a set of five MALDI-TOF MS biomarkers were selected to enable the discrimination of S. schleiferi subspecies. In addition, these biomarkers were predicted to represent highly conserved proteins, which could contribute to the identification of subspecies-specific proteins that could be used for improved subspecies identification in clinical samples., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Background: Group B Streptococcus (GBS) remains a major cause of neonatal sepsis and is also associated with invasive and noninvasive infections in pregnant women and non-pregnant adults, elderly and patients with underlying medical conditions. Ten capsular serotypes have been recognized, and determination of their distribution within a specific population or geographical region is important as they are major targets for the development of vaccine strategies. We have evaluated the characteristics of GBS isolates recovered from individuals with infections or colonization by this microorganism, living in different geographic regions of Brazil., Methods: A total of 434 isolates were identified and serotyped by conventional phenotypic tests. The determination of antimicrobial susceptibility was performed by the disk diffusion method. Genes associated with resistance to erythromycin (ermA, ermB, mefA) and tetracycline (tetK, tetL, tetM, tetO) as well as virulence-associated genes (bac, bca, lmb, scpB) were investigated using PCR. Pulsed-field gel electrophoresis (PFGE) was used to examine the genetic diversity of macrolide-resistant and of a number of selected macrolide-susceptible isolates., Results: Overall, serotypes Ia (27.6%), II (19.1%), Ib (18.7%) and V (13.6%) were the most predominant, followed by serotypes IV (8.1%) and III (6.7%). All the isolates were susceptible to the beta-lactam antimicrobials tested and 97% were resistant to tetracycline. Resistance to erythromycin and clindamycin were found in 4.1% and 3% of the isolates, respectively. Among the resistance genes investigated, tetM (99.3%) and tetO (1.8%) were detected among tetracycline-resistant isolates and ermA (39%) and ermB (27.6%) were found among macrolide-resistant isolates. The lmb and scpB virulence genes were detected in all isolates, while bac and bca were detected in 57 (13.1%) and 237 (54.6%) isolates, respectively. Molecular typing by PFGE showed that resistance to erythromycin was associated with a variety of clones., Conclusion: These findings indicate that GBS isolates circulating in Brazil have a variety of phenotypic and genotypic characteristics, and suggest that macrolide-resistant isolates may arise by both clonal spread and independent acquisition of resistance genes.