Group B Streptococcus (GBS) is the leading cause of invasive infections in newborns. The prevention of GBS neonatal disease relies on the administration of an intrapartum antibiotic prophylaxis to GBS-colonized women. In recent years, rapid intrapartum detection of GBS vaginal colonization using real-time nucleic acid amplification tests (NAATs) emerged as an alternative to antenatal culture screening methods.
ABSTRACT Streptococcus agalactiae is among the few pathogens that have not developed resistance to ß-lactam antibiotics despite decades of clinical use. The molecular basis of this long-lasting susceptibility has not been investigated, and it is not known whether specific mechanisms constrain the emergence of resistance. In this study, we report the conserved role of the signaling nucleotide cyclic-di-AMP in susceptibility to ß-lactams, demonstrating that inactivation of the phosphodiesterase GdpP in S. agalactiae confers ß-lactam tolerance. Characterization of the c-di-AMP signaling pathway reveals antagonistic regulation by the transcriptional factor BusR, which is activated by c-di-AMP and negatively regulates ß-lactam susceptibility through the BusAB transporter and AmaP/Asp23 cell envelope stress complex. Furthermore, we show that the simultaneous inhibition of osmolyte transporters activity and transcription by c-di-AMP has an additive effect, sustaining ß-lactam tolerance. Finally, we expanded the analysis of ß-lactam tolerance using random transposon mutagenesis, uncovering a convergent pattern of mutations involving the KhpAB small RNA chaperone and the S protein immunomodulator. Overall, our results demonstrate that c-di-AMP acts as a turgor pressure rheostat, coordinating an integrated response to cell wall weakening due to ß-lactam activity, and identify mechanisms that may foster antibiotic resistance in S. agalactiae .
Up to 25% of the E. coli strains isolated from the feces of healthy humans harbor the pks genomic island encoding the synthesis of colibactin, a genotoxic metabolite. Evidence is accumulating for an etiologic role of colibactin in colorectal cancer. Little is known about the conditions of expression of colibactin in the gut. The intestine is characterized by a unique oxygenation profile, with a steep gradient between the physiological hypoxic epithelial surface and the anaerobic lumen, which favors the dominance of obligate anaerobes. Here, we report that colibactin production is maximal under anoxic conditions and decreases with increased oxygen concentration. We show that the aerobic respiration control (ArcA) positively regulates colibactin production and genotoxicity of pks+ E. coli in response to oxygen availability. Thus, colibactin synthesis is inhibited by oxygen, indicating that the pks biosynthetic pathway is adapted to the anoxic intestinal lumen and to the hypoxic infected or tumor tissue.
Abstract Bacterial two-component systems (TCSs) are signaling modules that control physiology, adaptation, and host interactions. A typical TCS consists of a histidine kinase (HK) that activates a response regulator via phosphorylation in response to environmental signals. Here, we systematically test the effect of inactivating the conserved phosphatase activity of HKs to activate TCS signaling pathways. Transcriptome analyses of 14 HK mutants in Streptococcus agalactiae , the leading cause of neonatal meningitis, validate the conserved HK phosphatase mechanism and its role in the inhibition of TCS activity in vivo. Constitutive TCS activation, independent of environmental signals, enables high-resolution mapping of the regulons for several TCSs (e.g., SaeRS, BceRS, VncRS, DltRS, HK11030, HK02290) and reveals the functional diversity of TCS signaling pathways, ranging from highly specialized to interconnected global regulatory networks. Targeted analysis shows that the SaeRS-regulated PbsP adhesin acts as a signaling molecule to activate CovRS signaling, thereby linking the major regulators of host-pathogen interactions. Furthermore, constitutive BceRS activation reveals drug-independent activity, suggesting a role in cell envelope homeostasis beyond antimicrobial resistance. This study highlights the versatility of constitutive TCS activation, via phosphatase-deficient HKs, to uncover regulatory networks and biological processes.
Abstract Background The development of chatbot artificial intelligence (AI) has raised major questions about their use in healthcare. We assessed the quality and safety of the management suggested by Chat Generative Pre-training Transformer 4 (ChatGPT-4) in real-life practice for patients with positive blood cultures. Methods Over a 4-week period in a tertiary care hospital, data from consecutive infectious diseases (ID) consultations for a first positive blood culture were prospectively provided to ChatGPT-4. Data were requested to propose a comprehensive management plan (suspected/confirmed diagnosis, workup, antibiotic therapy, source control, follow-up). We compared the management plan suggested by ChatGPT-4 with the plan suggested by ID consultants based on literature and guidelines. Comparisons were performed by 2 ID physicians not involved in patient management. Results Forty-four cases with a first episode of positive blood culture were included. ChatGPT-4 provided detailed and well-written responses in all cases. AI’s diagnoses were identical to those of the consultant in 26 (59%) cases. Suggested diagnostic workups were satisfactory (ie, no missing important diagnostic tests) in 35 (80%) cases; empirical antimicrobial therapies were adequate in 28 (64%) cases and harmful in 1 (2%). Source control plans were inadequate in 4 (9%) cases. Definitive antibiotic therapies were optimal in 16 (36%) patients and harmful in 2 (5%). Overall, management plans were considered optimal in only 1 patient, as satisfactory in 17 (39%), and as harmful in 7 (16%). Conclusions The use of ChatGPT-4 without consultant input remains hazardous when seeking expert medical advice in 2023, especially for severe IDs.
Journal Article High-level expression of chromosomally encoded SHV-1 β-lactamase reduces the susceptibility to cefiderocol of clinical isolates of Klebsiella pneumoniae Get access Rym Charfi, Rym Charfi Hôpitaux Universitaires Paris Centre, Site Cochin, Service de Bactériologie, Assistance Publique Hôpitaux de Paris, Paris, France Search for other works by this author on: Oxford Academic PubMed Google Scholar Asmaa Tazi, Asmaa Tazi Hôpitaux Universitaires Paris Centre, Site Cochin, Service de Bactériologie, Assistance Publique Hôpitaux de Paris, Paris, FranceUniversité de Paris, Institut Cochin, INSERM U1016, CNRS UMR8104, Paris, France https://orcid.org/0000-0001-9531-9177 Search for other works by this author on: Oxford Academic PubMed Google Scholar Youssouf Sereme, Youssouf Sereme Université Paris Cité, INSERM, CNRS, Institut Necker Enfants Malades, Laboratory of Bacteriology, 75015 Paris, France Search for other works by this author on: Oxford Academic PubMed Google Scholar Céline Plainvert, Céline Plainvert Hôpitaux Universitaires Paris Centre, Site Cochin, Service de Bactériologie, Assistance Publique Hôpitaux de Paris, Paris, FranceUniversité de Paris, Institut Cochin, INSERM U1016, CNRS UMR8104, Paris, France Search for other works by this author on: Oxford Academic PubMed Google Scholar Hélène Poupet, Hélène Poupet Hôpitaux Universitaires Paris Centre, Site Cochin, Service de Bactériologie, Assistance Publique Hôpitaux de Paris, Paris, France Search for other works by this author on: Oxford Academic PubMed Google Scholar Alexandra Doloy, Alexandra Doloy Hôpitaux Universitaires Paris Centre, Site Cochin, Service de Bactériologie, Assistance Publique Hôpitaux de Paris, Paris, France Search for other works by this author on: Oxford Academic PubMed Google Scholar Cécile Guyonnet, Cécile Guyonnet Hôpitaux Universitaires Paris Centre, Site Cochin, Service de Bactériologie, Assistance Publique Hôpitaux de Paris, Paris, FranceUniversité de Paris, Institut Cochin, INSERM U1016, CNRS UMR8104, Paris, France Search for other works by this author on: Oxford Academic PubMed Google Scholar Philippe Morand, Philippe Morand Hôpitaux Universitaires Paris Centre, Site Cochin, Service de Bactériologie, Assistance Publique Hôpitaux de Paris, Paris, FranceUniversité de Paris, Institut Cochin, INSERM U1016, CNRS UMR8104, Paris, France Search for other works by this author on: Oxford Academic PubMed Google Scholar Julien Loubinoux, Julien Loubinoux Hôpitaux Universitaires Paris Centre, Site Cochin, Service de Bactériologie, Assistance Publique Hôpitaux de Paris, Paris, France Search for other works by this author on: Oxford Academic PubMed Google Scholar Claire Poyart, Claire Poyart Hôpitaux Universitaires Paris Centre, Site Cochin, Service de Bactériologie, Assistance Publique Hôpitaux de Paris, Paris, FranceUniversité de Paris, Institut Cochin, INSERM U1016, CNRS UMR8104, Paris, France Search for other works by this author on: Oxford Academic PubMed Google Scholar ... Show more Hedi Mammeri Hedi Mammeri Hôpitaux Universitaires Paris Centre, Site Cochin, Service de Bactériologie, Assistance Publique Hôpitaux de Paris, Paris, FranceUniversité Paris Cité, INSERM, CNRS, Institut Necker Enfants Malades, Laboratory of Bacteriology, 75015 Paris, France Corresponding author. E-mail: hedi.mammeri@aphp.fr Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of Antimicrobial Chemotherapy, dkae143, https://doi.org/10.1093/jac/dkae143 Published: 24 May 2024
Abstract Streptococcus agalactiae is among the few pathogens that have not developed resistance to ß-lactam antibiotics despite decades of clinical use. The molecular basis of this long-lasting susceptibility has not been investigated, and it is not known whether specific mechanisms constrain the emergence of resistance. In this study, we first report ß-lactam tolerance due to the inactivation of the c-di-AMP phosphodiesterase GdpP. Mechanistically, tolerance depends on antagonistic regulation by the repressor BusR, which is activated by c-di-AMP and negatively regulates ß-lactam susceptibility through the BusAB osmolyte transporter and the AmaP/Asp23/GlsB cell envelope stress complex. The BusR transcriptional response is synergistic with the simultaneous allosteric inhibition of potassium and osmolyte transporters by c-di-AMP, which individually contribute to low-level ß-lactam tolerance. Genome-wide transposon mutagenesis confirms the role of GdpP and highlights functional interactions between a lysozyme-like hydrolase, the KhpAB RNA chaperone and the protein S immunomodulator in the response of GBS to ß-lactam. Overall, we demonstrate that c-di-AMP acts as a turgor pressure rheostat, coordinating an integrated response at the transcriptional and post-translational levels to cell wall weakening caused by ß-lactam activity, and reveal additional mechanisms that could foster resistance.
ABSTRACT Each bacterial species has specific regulatory systems to control physiology, adaptation, and host interactions. One challenge posed by this diversity is to define the evolving gene regulatory networks. This study aims to characterise two-component systems (TCS) in Streptococcus agalactiae , the main cause of neonatal meningitis. Here we demonstrate signal-independent activation of signalling pathways by systematically targeting the conserved mechanism of phosphatase activity of the 14 histidine kinases of the two main TCS families. Transcriptomic analysis resolves most pathways with high resolution, encompassing specialized, connected, and global regulatory systems. The activated network notably reveals the connection between CovRS and SaeRS signaling through the adhesin PbsP, linking the main regulators of host interactions to balance pathogenicity. Additionally, constitutive activation of the BceRS system reveals its role in cell envelope homeostasis beyond antimicrobial resistance. Overall, this study demonstrates the generalizability and versatility of TCS genetic activation to uncover regulatory logics and biological processes.
