Biology subjects

Manning, S. D.

Publications and source records attributed to Manning, S. D..

5 recordsLinked to original sources

bioRxiv2024

Intrapartum antibiotic prophylaxis selects for mutators in group B streptococci among persistently colonized patients

Through vaginal colonization, GBS causes severe outcomes including neonatal sepsis and meningitis. Although intrapartum antibiotic prophylaxis (IAP) has reduced neonatal disease rates, persistent GBS colonization has been observed in patients following prophylaxis. To determine whether IAP selects for genomic signatures that enhance GBS survival and persistence, a pangenome analysis was performed on 97 isolates from 58 participants before (prenatal) and after (postpartum) IAP/childbirth. Thirty-one of the 34 paired strains from participants with persistent colonization clustered together in the core gene phylogeny, suggesting that the strains recovered at the postpartum sampling were highly similar to those recovered at the prenatal visit. A core-gene mutation analysis identified mutations in 74% (n=23) of the 31 postpartum genomes when compared to the prenatal strains of the same multilocus sequence type recovered from the same individuals. Several strains had acquired mutations in the same colonization-associated genes, though two postpartum strains accounted for most of the mutations. These two outliers were classified as mutators based on high mutation rates and mutations within DNA repair system genes. Increased biofilm production was observed in half of the postpartum strains relative to the prenatal strains, which is supported by the presence of point mutations in genes associated with adherence. Together, these findings suggest that antibiotics may impose a selective pressure on GBS that selects for mutations and phenotypes that promote adaptation and survival in vivo. Enhanced survival in the genitourinary tract can lead to persistent colonization, increasing the likelihood of invasive disease in subsequent pregnancies and in newborns following IAP.

evolutionary biology↗

bioRxiv2023

Persistent effects of intramammary ceftiofur treatment on the gut microbiome and antibiotic resistance in dairy cattle

Intramammary (IMM) ceftiofur treatment is commonly used in dairy farms to prevent mastitis, though its impact on the cattle gut microbiome and selection of antibiotic-resistant bacteria has not been elucidated. Herein, we enrolled 40 healthy dairy cows after lactation: 20 were treated with IMM ceftiofur (Spectramast(R)DC) and a non-antibiotic internal teat sealant (bismuth subnitrate) and 20 (controls) received only bismuth subnitrate. Fecal samples were collected before (day -1) and after treatment (weeks 1, 2, 3, 5, 7, and 9) for bacterial quantification and metagenomic next-generation sequencing. Overall, 90% and 24% of the 278 samples had Gram-negative bacteria with resistance to ampicillin and ceftiofur, respectively. Most of the cows treated with ceftiofur did not have an increase in the number of resistant bacteria; however, a subset (25%) shed higher levels of ceftiofur-resistant bacteria for up to 2 weeks post-treatment. At week 5, the antibiotic-treated cows had lower microbiome abundance and richness, whereas a greater abundance of genes encoding extended-spectrum {beta}-lactamases (ESBLs), CfxA, ACI-1, and CMY, was observed at weeks 1, 5 and 9. Moreover, the contig and network analyses detected associations between {beta}-lactam resistance genes and phages, mobile genetic elements, and specific genera. Commensal bacterial populations belonging to Bacteroidetes most often possessed ESBL genes followed by members of Enterobacteriaceae. This study highlights variable, persistent effects of IMM ceftiofur treatment on the gut microbiome and resistome in dairy cattle. Antibiotic-treated cattle had an increased abundance of specific taxa and genes encoding ESBL production that persisted for 9 weeks, while fecal shedding of ESBL-producing Enterobacteriaceae varied across animals. Together, these findings highlight the need for additional studies that identify factors linked to shedding levels and the dissemination and persistence of resistance determinants on dairy farms in different geographic locations.

microbiology↗

bioRxiv2023

Recovery of the gut microbiome following enteric infection and persistence of antimicrobial resistance genes in specific microbial hosts

Enteric pathogens cause widespread foodborne illness and are increasingly found to harbor antimicrobial resistance. The ecological impact of these pathogens on the human gut microbiome and resistome, however, has yet to be fully elucidated. This study applied shotgun metagenome sequencing to stools from 60 patients (cases) with enteric bacterial infections for comparison to stools collected from the same patients post-recovery (follow-ups). Overall, the case samples harbored more antimicrobial resistance genes (ARGs) and had greater resistome diversity than the follow-up samples (p<0.001), while follow-ups had much more diverse microbiomes (p<0.001). Although cases were primarily defined by genera Escherichia, Salmonella, and Shigella along with ARGs for multi-compound and multidrug resistance, follow-ups had a greater abundance of Bacteroidetes and Firmicutes phyla and genes for tetracycline, macrolides, lincosamides, and streptogramins (MLS), and aminoglycoside resistance. A host-tracking analysis revealed that Escherichia was the primary carrier of ARGs in both cases and follow-ups, with a greater abundance occurring during infection. Eleven distinct extended spectrum beta-lactamases (ESBLs) were identified during infection, some of which appear to be lost or transferred to different microbial hosts upon recovery. The increasing incidence of disease caused by foodborne pathogens, coupled with their evolving role in harboring and transferring antimicrobial resistance determinants within communities, justifies further examination of the repercussions of enteric infection on human gut ecology.

microbiology↗

bioRxiv2022

Group B streptococcal membrane vesicles induce proinflammatory cytokine production and are sensed in an NLRP3 inflammasome-dependent mechanism in human macrophages

Group B Streptococcus (GBS) is a major cause of fetal and neonatal mortality worldwide. Many of the adverse effects associated with invasive GBS are associated with inflammation that leads to chorioamnionitis, preterm birth, sepsis, and meningitis; therefore, understanding bacterial factors that promote inflammation is of critical importance. Membrane vesicles (MVs), which are produced by many pathogenic and non-pathogenic bacteria, may modulate host inflammatory responses. In mice, GBS MVs injected intra-amniotically can induce preterm birth and fetal death. Although it is known that GBS MVs induce large-scale leukocyte recruitment into infected tissues, the immune effectors driving these responses are unclear. Here, we hypothesized that macrophages respond to GBS-derived MVs by producing proinflammatory cytokines and are recognized through one or more pattern recognition receptors. We show that THP-1 macrophage-like cells produce high levels of neutrophil- and monocyte-specific chemokines in response to MVs derived from different clinical isolates of GBS. Interleukin (IL)-1{beta} was significantly upregulated in response to MVs, which was independent of NF-kB signaling but dependent on both caspase-1 and NLRP3. These data indicate that MVs contain one or more pathogen-associated molecular patterns that can be sensed by the immune system. Furthermore, this study identifies the NLRP3 inflammasome as a novel sensor of GBS MVs. Our data additionally indicate that MVs may serve as immune effectors that can be targeted for immunotherapeutics, particularly given that similar responses were observed across this subset of GBS isolates.

immunology↗

bioRxiv2021

Production and composition of group B streptococcal membrane vesicles varies across diverse lineages

Although the neonatal and fetal pathogen Group B Streptococcus (GBS) asymptomatically colonizes the vaginal tract of [~]30% of pregnant women, only a fraction of their offspring develops invasive disease. We and others have postulated that these dimorphic clinical phenotypes are driven by strain variability; however, the bacterial factors that promote these divergent clinical phenotypes remain unclear. It was previously shown that GBS produces membrane vesicles (MVs) that contain active virulence factors capable of inducing adverse pregnancy outcomes. Because the relationship between strain variation and vesicle composition or production is unknown, we sought to quantify MV production and examine the protein composition, using label-free proteomics on MVs produced by diverse clinical GBS strains representing three phylogenetically distinct lineages. We found that MV production varied across strains, with certain strains displaying nearly two-fold increases in production relative to others. Hierarchical clustering and principal component analysis of the proteomes revealed that MV composition is lineage-dependent but independent of clinical phenotype. Multiple proteins that contribute to virulence or immunomodulation, including hyaluronidase, C5a peptidase, and sialidases, were differentially abundant in MVs, and were partially responsible for this divergence. Together, these data indicate that production and composition of GBS MVs vary in a strain-dependent manner, suggesting that MVs have lineage-specific functions relating to virulence. Such differences may contribute to variation in clinical phenotypes observed among individuals infected with GBS strains representing distinct lineages.

microbiology↗