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Journal of Global Antimicrobial... Jun 2024Streptococcus agalactiae is a recognized pathogen that primarily affects infants and pregnant women. However, its increasingly important role in causing invasive...
BACKGROUND
Streptococcus agalactiae is a recognized pathogen that primarily affects infants and pregnant women. However, its increasingly important role in causing invasive infections among non-pregnant adults has become a significant health concern due to the severity and variety of its clinical impacts.
METHODS
Nonduplicate S. agalactiae clinical strains associated with clinical infections (n=139) were isolated from non-pregnant adults in Shandong, China. Antibiotic susceptibility testing, whole-genome sequencing, and genomic analyses were conducted to characterize the genome and identify resistance features of these strains.
RESULTS
The strains exhibited universal susceptibility to penicillin, ampicillin, cefotaxime, meropenem, linezolid, and vancomycin. Notably, high resistance rates were observed for erythromycin (91.4%), clindamycin (89.2%), levofloxacin (84.2%), tetracycline (54.0%) and, to a lesser extent, chloramphenicol (12.9%). Serotyping revealed seven serotypes and one non-typeable strain. Serotypes Ia, Ib, III, and V predominated, representing 95.7% of the strains. Nineteen sequence types were categorized into seven clonal complexes, with CC10 being the most prevalent at 48.9%. The resistance genes mreA (100%), ermB (70.5%), and tetM (46.0%) were commonly detected. All the isolates carried at least one pilus backbone determinant and one alpha-like protein gene, with the PI-1+PI-2a and the bca gene being the most frequent at 84.2% and 54.7%, respectively.
CONCLUSIONS
While S. agalactiae strains in non-pregnant adults retain sensitivity to β-lactam antibiotics, the elevated resistance to erythromycin, clindamycin, levofloxacin, and tetracycline is concerning. Given the growing elderly population worldwide, the burden of S. agalactiae infections is significant. Continuous surveillance of serotype distribution and antibiotic resistance patterns is imperative for targeted prevention and therapeutic strategies.
PubMed: 38866137
DOI: 10.1016/j.jgar.2024.06.001 -
BioRxiv : the Preprint Server For... May 2024In nature, organisms experience combinations of stressors. However, laboratory studies typically simplify reality and focus on the effects of an individual stressor....
In nature, organisms experience combinations of stressors. However, laboratory studies typically simplify reality and focus on the effects of an individual stressor. Here, we use a microfluidic approach to simultaneously provide a physical stressor (shear flow) and a chemical stressor (H O ) to the human pathogen . By treating cells with levels of flow and H O that commonly co-occur in nature, we discover that previous reports significantly overestimate the H O levels required to block bacterial growth. Specifically, we establish that flow increases H O effectiveness 50-fold, explaining why previous studies lacking flow required much higher concentrations. Using natural H O levels, we identify the core H O regulon, characterize OxyR-mediated dynamic regulation, and dissect the redundant roles of multiple H O scavenging systems. By examining single-cell behavior, we serendipitously discover that the combined effects of H O and flow block pilus-driven surface migration. Thus, our results counter previous studies and reveal that natural levels of H O and flow synergize to restrict bacterial colonization and survival. By studying two stressors at once, our research highlights the limitations of oversimplifying nature and demonstrates that physical and chemical stress can combine to yield unpredictable effects.
PubMed: 38853869
DOI: 10.1101/2024.05.27.595753 -
Gut Microbes 2024Comensal () and are often linked to gut inflammation. However, the causes for variability of pro-inflammatory surface antigens that affect gut commensal/opportunistic...
Comensal () and are often linked to gut inflammation. However, the causes for variability of pro-inflammatory surface antigens that affect gut commensal/opportunistic dualism in remain unclear. By using the classical lipopolysaccharide/O-antigen ' operon' in as a surface antigen model (5-gene-cluster ), and a recent typing strategy for strain classification, we characterized the integrity and conservancy of the entire operon in . Through exploratory analysis of complete genomes and metagenomes, we discovered that most have the operon fragmented into nonrandom patterns of gene-singlets and doublets/triplets, termed 'gene-clusters', or rfb-'minioperons' if predicted as transcriptional. To reflect global operon integrity, contiguity, duplication, and fragmentation principles, we propose a six-category (infra/supra-numerary) cataloging system and a Global Operon Profiling System for bacteria. Mechanistically, genomic sequence analyses revealed that operon fragmentation is driven by intra-operon insertions of predominantly -DNA () and likely natural selection in gut-wall specific micro-niches or micropathologies. -insertions, also detected in other antigenic operons (fimbriae), but not in operons deemed essential (ribosomal), could explain why have fewer KEGG-pathways despite large genomes. DNA insertions, overrepresenting DNA-exchange-avid () species, impact our interpretation of functional metagenomics data by inflating by inflating gene-based pathway inference and by overestimating 'extra-species' abundance. Of disease relevance, species isolated from cavitating/cavernous fistulous tract (CavFT) microlesions in Crohn's Disease have supra-numerary fragmented operons, stimulate TNF-alpha from macrophages with low potency, and do not induce hyperacute peritonitis in mice compared to CavFT . The impact of 'foreign-DNA' insertions on pro-inflammatory operons, metagenomics, and commensalism/opportunism requires further studies to elucidate their potential for novel diagnostics and therapeutics, and to elucidate the role of co-existing pathobionts in Crohn's disease microlesions.
Topics: Operon; Mice; Gastrointestinal Microbiome; Animals; Humans; Metagenomics; Crohn Disease; Bacteroidetes; Antigens, Bacterial; Genome, Bacterial; Enterobacteriaceae
PubMed: 38841888
DOI: 10.1080/19490976.2024.2350150 -
Current Biology : CB Jun 2024Strain-specific pili enable Vibrio cholerae bacteria to adhere to each other and form aggregates in liquid culture. A new study focuses on strains with less specific,...
Strain-specific pili enable Vibrio cholerae bacteria to adhere to each other and form aggregates in liquid culture. A new study focuses on strains with less specific, promiscuous pili and suggests a role for contact-dependent bacterial killing in shaping the composition of these aggregates.
Topics: Vibrio cholerae; Fimbriae, Bacterial; Bacterial Adhesion
PubMed: 38834027
DOI: 10.1016/j.cub.2024.04.042 -
Nanoscale Jun 2024Type IV pili (TFP) contribute to the ability of microbes such as to engage with and move across surfaces. We reported previously that TFP generate retractive forces of...
Type IV pili (TFP) contribute to the ability of microbes such as to engage with and move across surfaces. We reported previously that TFP generate retractive forces of ∼30 pN and provided indirect evidence that TFP-mediated surface attachment was enhanced in the presence of the Pel polysaccharide. Here, we use different mutants defective in flagellar, Pel production or TFP production - alone or in combination - to decipher the relative contribution of these biofilm-promoting factors for adhesion. By means of atomic force microscopy (AFM), we show that mutating the flagellum (Δ mutant) results in an increase in Pel polysaccharide production, but this increase in Pel does not result in an increase in surface adhesive properties compared to those previously described for the WT strain. By blocking Pel production in the Δ mutant (ΔΔ), we directly show that TFP play a major role in the adhesion of the bacteria to hydrophobic AFM tips, but that the adhesion force is only slightly impaired by the absence of Pel. Inversely, performing single-cell force spectroscopy measurements with the mutant lacking TFP (ΔΔ) reveals that the Pel can modulate the attachment of the bacteria to a hydrophobic substrate in a time-dependent manner. Finally, little adhesion was detected for the ΔΔΔ triple mutant, suggesting that both TFP and Pel polysaccharide make a substantial contribution to bacteria-substratum interaction events. Altogether, our data allow us to decipher the relative contribution of Pel and TFP in the early attachment by .
Topics: Pseudomonas aeruginosa; Microscopy, Atomic Force; Fimbriae, Bacterial; Bacterial Adhesion; Polysaccharides, Bacterial; Biofilms; Flagella; Bacterial Proteins; Mutation
PubMed: 38832761
DOI: 10.1039/d4nr01415d -
Preventive Veterinary Medicine Jul 2024Despite the prevalence of co-infections and the association of over 50 viral and 46 bacterial pathogens with pig diseases, little is known about their simultaneous...
Despite the prevalence of co-infections and the association of over 50 viral and 46 bacterial pathogens with pig diseases, little is known about their simultaneous occurrence, particularly in commercial pig farming environments where health programs are in place. To address this knowledge gap, this study aimed to evaluate the pathogen threshold of respiratory and enteric pathogens in pig herds using the Pork MultiPath™ (PMP1 and PMP2, respiratory and enteric respectively) technology, which detects multiple pathogens simultaneously in a single reaction with high sensitivity and specificity. In this study the most prevalent respiratory pathogens, Mycoplasma hyrohinis, Pasteurella multocida, and Haemophilus parasuis detected by PMP1 were effectively controlled during the nursery stage through strategic treatment with tiamulin. Even though the major respiratory incidences were reduced, the recorded coughing and sneezing rates were associated with the levels of H. parasuis and M. hyrohinis, which were set at 1356 and 1275 copies/reaction, respectively. In addition, one of the identified co-infection patterns indicated a strong relationship between the occurrence of H. parasuis and M. hyorhinis at the sample and pen levels, highlighting the high likelihood of detecting these two pathogens together. Testing with enteric panel PMP2 revealed that the most frequently detected virulence factors during the early nursery stage were Escherichia coli genes for toxins - ST1, ST2, and fimbriae - F4 and F18. Moreover, a co-infection with Rotavirus B and C was often observed during the nursery stage, and a strong positive correlation between these two markers has been identified. Additionally, the levels of several markers, namely E. coli F4, F5, F18, LT, ST1, and ST2, have been associated with a higher likelihood of sickness in pig populations. In addition, the onset of Brachyspira pilosicoli during the nursery and grower stages was found to be associated with an increased risk of diarrhoea, with a set threshold at around 500 copies/reaction. Although simultaneous detection of multiple pathogens is not yet widely used in the pig industry, it offers a significant advantage in capturing the diversity and interactions of co-infections. Testing pooled samples with Pork MultiPath™ is cost-effective and practical to regularly monitor the health status of pig populations.
Topics: Animals; Swine Diseases; Swine; Coinfection; Epidemiological Monitoring
PubMed: 38820832
DOI: 10.1016/j.prevetmed.2024.106237 -
Journal of Bacteriology Jun 2024Many prokaryotes use swimming motility to move toward favorable conditions and escape adverse surroundings. Regulatory mechanisms governing bacterial flagella-driven...
Many prokaryotes use swimming motility to move toward favorable conditions and escape adverse surroundings. Regulatory mechanisms governing bacterial flagella-driven motility are well-established; however, little is yet known about the regulation underlying swimming motility propelled by the archaeal cell surface structure, the archaella. Previous research showed that the deletion of the adhesion pilins (PilA1-6), subunits of the type IV pili cell surface structure, renders the model archaeon non-motile. In this study, we used ethyl methanesulfonate mutagenesis and a motility assay to identify motile suppressors of the ∆[] strain. Of the eight suppressors identified, six contain missense mutations in archaella biosynthesis genes, and expression of and mutant constructs in the respective multi-deletion strains ∆[]∆ and ∆[]∆ confirmed their role in suppressing the ∆[] motility defect. Additionally, three suppressors harbor co-occurring disruptive missense and nonsense mutations in , a gene encoding a proposed regulatory protein. A deletion of resulted in hypermotility, while expression in wild-type cells led to decreased motility. Moreover, quantitative real-time PCR analysis revealed that in wild-type cells, higher expression levels of , , and the archaellin gene were observed in motile early-log phase rod-shaped cells compared to non-motile mid-log phase disk-shaped cells. Conversely, ∆ cells, which form rods during both early- and mid-log phases, exhibited similar expression levels of genes in both growth phases. Our findings contribute to a deeper understanding of the mechanisms governing archaeal motility, highlighting the involvement of ArlI, ArlJ, and CirA in pilin-mediated motility regulation.IMPORTANCEArchaea are close relatives of eukaryotes and play crucial ecological roles. Certain behaviors, such as swimming motility, are thought to be important for archaeal environmental adaptation. Archaella, the archaeal motility appendages, are evolutionarily distinct from bacterial flagella, and the regulatory mechanisms driving archaeal motility are largely unknown. Previous research has linked the loss of type IV pili subunits to archaeal motility suppression. This study reveals three proteins involved in pilin-mediated motility regulation, offering a deeper understanding of motility regulation in this understudied domain while also paving the way for uncovering novel mechanisms that govern archaeal motility. Understanding archaeal cellular processes will help elucidate the ecological roles of archaea as well as the evolution of these processes across domains.
Topics: Haloferax volcanii; Fimbriae Proteins; Archaeal Proteins; Gene Expression Regulation, Archaeal
PubMed: 38819156
DOI: 10.1128/jb.00089-24 -
Antonie Van Leeuwenhoek May 2024Pseudoalteromonas piscicida 2515, isolated from Litopenaeus vannamei culture water, is a potential marine probiotic with broad anti-Vibrio properties. However, genomic...
Pseudoalteromonas piscicida 2515, isolated from Litopenaeus vannamei culture water, is a potential marine probiotic with broad anti-Vibrio properties. However, genomic information on P. piscicida 2515 is scarce. In this study, the general genomic characteristics and probiotic properties of the P. piscicida 2515 strain were analysed. In addition, we determined the antibacterial mechanism of this bacterial strain by scanning electron microscopy (SEM). The results indicated that the whole-genome sequence of P. piscicida 2515 contained one chromosome and one plasmid, including a total length of 5,541,406 bp with a G + C content of 43.24%, and 4679 protein-coding genes were predicted. Various adhesion-related genes, amino acid and vitamin metabolism and biosynthesis genes, and stress-responsive genes were found with genome mining tools. The presence of genes encoding chitin, bromocyclic peptides, lantibiotics, and sactipeptides showed the strong antibacterial activity of the P. piscicida 2515 strain. Moreover, in coculture with Vibrio anguillarum, P. piscicida 2515 displayed vesicle/pilus-like structures located on its surface that possibly participated in its bactericidal activity, representing an antibacterial mechanism. Additionally, 16 haemolytic genes and 3 antibiotic resistance genes, including tetracycline, fluoroquinolone, and carbapenem were annotated, but virulence genes encoding enterotoxin FM (entFM), cereulide (ces), and cytotoxin K were not detected. Further tests should be conducted to confirm the safety characteristics of P. piscicida 2515, including long-term toxicology tests, ecotoxicological assessment, and antibiotic resistance transfer risk assessment. Our results here revealed a new understanding of the probiotic properties and antibacterial mechanism of P. piscicida 2515, in addition to theoretical information for its application in aquaculture.
Topics: Pseudoalteromonas; Vibrio; Whole Genome Sequencing; Genome, Bacterial; Animals; Probiotics; Anti-Bacterial Agents; Penaeidae; Phylogeny; Base Composition
PubMed: 38809302
DOI: 10.1007/s10482-024-01974-w -
European Journal of Clinical... May 2024Corynebacterium striatum is an emerging nosocomial pathogen. This is the first report showing the presence of three distinct multidrug resistant lineages of C. striatum...
Corynebacterium striatum is an emerging nosocomial pathogen. This is the first report showing the presence of three distinct multidrug resistant lineages of C. striatum among patients in a UK hospital. The presence of ErmX, Tet(W), Bla and AmpC proteins, and mutations in gyrA gene are associated with the resistance to clindamycin, doxycycline, penicillin and moxifloxacin, respectively. These strains are equipped with several corynebacterial virulence genes including two SpaDEF-type and a novel pilus gene cluster, which needs further molecular characterisation. This study highlights a need of developing an active surveillance strategy for routine monitoring and preventing potential cross-transmission among susceptible patients.
PubMed: 38801486
DOI: 10.1007/s10096-024-04857-0 -
Emerging Microbes & Infections Dec 2024Ceftazidime-avibactam resistance attributable to the gene mutation is increasingly documented in clinical settings. In this study, we characterized the mechanisms...
Ceftazidime-avibactam resistance attributable to the gene mutation is increasingly documented in clinical settings. In this study, we characterized the mechanisms leading to the development of ceftazidime-avibactam resistance in ST11-K47 hypervirulent that harboured the gene. This strain possessed fimbriae and biofilm, demonstrating pathogenicity. Compared with the wild-type KPC-2 carbapenemase, the novel KPC-135 enzyme exhibited a deletion of Glu168 and Leu169 and a 15-amino acid tandem repeat between Val262 and Ala276. The gene was located within the Tn transposon truncated by IS and carried on an IncFII/IncR-type plasmid. Compared to the -positive cloned strain, only the MIC of ceftazidime increased against -positive and wasn't inhibited by avibactam (MIC 32 μg/mL), while clavulanic acid and vaborbactam demonstrated some inhibition. Kinetic parameters revealed that KPC-135 exhibited a lower and cat/ with ceftazidime and carbapenems, and a higher (∼26-fold) 50% inhibitory concentration with avibactam compared to KPC-2. The KPC-135 enzyme exerted a detrimental effect on fitness relative to the wild-type strain. Furthermore, this strain possessed hypervirulent determinants, which included the IncHI1B/FIB plasmid with and expression of type 1 and 3 fimbriae. In conclusion, we reported a novel KPC variant, KPC-135, in a clinical ST11-K47 hypervirulent strain, which conferred ceftazidime-avibactam resistance, possibly through increased ceftazidime affinity and decreased avibactam susceptibility. This strain simultaneously harboured resistance and virulence genes, posing an elevated challenge in clinical treatment.
Topics: Ceftazidime; Klebsiella pneumoniae; Azabicyclo Compounds; Drug Combinations; Anti-Bacterial Agents; Klebsiella Infections; Microbial Sensitivity Tests; beta-Lactamases; Bacterial Proteins; Humans; Virulence; Biofilms; Drug Resistance, Multiple, Bacterial; Plasmids; Animals
PubMed: 38801099
DOI: 10.1080/22221751.2024.2361007