The bacterial replication origin BUS promotes nucleobase capture.

Genome duplication is essential for the proliferation of cellular life and this process is generally initiated by dedicated replication proteins at chromosome origins. In bacteria, DNA replication is initiated by the ubiquitous DnaA protein, which assembles into an oligomeric complex at the chromosome origin (oriC) that engages both double-stranded DNA (dsDNA) and single-stranded DNA (ssDNA) to promote DNA duplex opening. However, the mechanism of DnaA specifically opening a replication origin was unknown. Here we show that Bacillus subtilis DnaAATP assembles into a continuous oligomer at the site of DNA melting, extending from a dsDNA anchor to engage a single DNA strand. Within this complex, two nucleobases of each ssDNA binding motif (DnaA-trio) are captured within a dinucleotide binding pocket created by adjacent DnaA proteins. These results provide a molecular basis for DnaA specifically engaging the conserved sequence elements within the bacterial chromosome origin basal unwinding system (BUS).

Defining standard and high dosages for ß-lactam agents administered by intermittent, prolonged or continuous infusion: a PK/PD simulation study.

BACKGROUND: The new definitions of antimicrobial susceptibility categories proposed by EUCAST in 2020 require the definition of standard and high dosages of antibiotic. For injectable ß-lactams, standard and high dosages have been proposed for short-infusion regimens only. OBJECTIVES: To evaluate dosages for ß-lactams administered by prolonged infusion (PI) and continuous infusion (CI). METHODS: Monte Carlo simulations were performed for seven injectable ß-lactams: aztreonam, cefepime, cefotaxime, cefoxitin, ceftazidime, piperacillin and temocillin. Various dosage regimens based on short infusion, PI or CI were simulated in virtual patients. Pharmacokinetic (PK) profiles and PTAs were obtained based on reference population PK models, as well as PK/pharmacodynamic targets and MIC breakpoints proposed by EUCAST. Alternative dosage regimens associated with PTA values similar to those of recommended dosages up to the breakpoints were considered acceptable. RESULTS: Adequate PTAs were confirmed for most EUCAST short-infusion dosage regimens. A total of 9 standard and 14 high dosages based on PI (3 to 4 h) or CI were identified as alternatives. For cefepime and aztreonam, only PI and CI regimens could achieve acceptable PTAs for infections caused by Pseudomonas spp.: 2 g q8h as PI of 4 h or 6 g/24 h CI for cefepime; 2 g q6h as PI of 3 h or 6 g/24 h CI for aztreonam. CONCLUSIONS: These alternative standard and high dosage regimens are expected to provide antibiotic exposure compatible with new EUCAST definitions of susceptibility categories and associated MIC breakpoints. However, further clinical evaluation is necessary.

[Lyme borreliosis]. / Borréliose de Lyme.

LYME BORRELIOSIS. Lyme borreliosis (LB) is the most common vector-borne disease in the Northern Hemisphere, caused by the bacterium Borrelia burgdorferi sensu lato, transmitted to humans by a bite of ticks Ixodes. Prevention is based on simple measures to evict ticks, and on their rapid extractionin the event of a bite. The diagnosis of LB is based on 3 arguments: an exposure to tick bites; clinically compatible symptoms (cutaneous, neurological or rheumatological manifestations, +/- functional symptoms such as fatigue or polyarthromyalgia), evolving in 3 stages (early localized or erythema migrans, early or late disseminated LB); a positive two-tier serological test (ELISA +/- Western-Blot). Serology can be negative for the first 6 weeks, without excluding the diagnosis. Since serology can remain positive for life, evolution is only evaluated clinically. LB treatment is mainly based on doxycycline for 14 to 28 days, depending on the clinical stage and manifestations, without demonstrated interest in prolonging it, even if symptoms persist. Nonetheless their management is crucial as often responsible for medical wandering. Attentive listening to the patient is essential. The prognosis of LB in the medium-term is favorable, especially if they beneficiate of an early management.

BORRÉLIOSE DE LYME. La borréliose de Lyme (BL) est la maladie vectorielle la plus fréquente de l'hémisphère Nord. Elle est due à la bactérie Borrelia burgdorferi sensu lato, transmise à l'homme lors d'une piqûre de tique infectée du genre Ixodes. La prévention repose sur des mesures simples d'éviction des tiques, et sur leur extraction rapide en cas de piqûre. Le diagnostic de la BL est basé sur un trépied : une exposition aux piqûres de tiques ; une clinique compatible (manifestations cutanées, neurologiques ou articulaires, éventuellement accompagnées de symptômes fonctionnels comme une fatigue, des polyarthromyalgies…), évoluant en trois phases (localisée précoce ou érythème migrant, disséminée précoce et tardive) ; une sérologie positive en deux temps (ELISA +/- western-blot). La sérologie peut être négative les 6 premières semaines, sans exclure le diagnostic. La sérologie pouvant rester positive à vie, l'évolution est uniquement évaluée cliniquement. Le traitement de la BL repose principalement sur la doxycycline, pendant 14 à 28 jours selon le stade clinique et le type d'atteinte. Il n'y a pas d'intérêt démontré à prolonger l'antibiothérapie, même en cas de persistance de symptômes. Néanmoins la prise en charge de ceux-ci (réadaptation physique, thérapies brèves, etc.) est fondamentale car ils sont souvent à l'origine d'une errance médicale. Une écoute attentive du patient est essentielle. Le pronostic des BL à moyen terme est favorable, ce d'autant que leur prise en charge est précoce.

HU Knew? Bacillus subtilis HBsu Is Required for DNA Replication Initiation.

The prokaryotic nucleoid-associated protein (NAP) HU is both highly conserved and ubiquitous. Deletion of HU causes pleiotropic phenotypes, making it difficult to uncover the critical functions of HU within a bacterial cell. In their recent work, Karaboja and Wang (J Bacteriol 204:e00119-22, 2022, https://doi.org/10.1128/JB.00119-22) show that one essential function of Bacillus subtilis HU (HBsu) is to drive the DnaA-dependent initiation of DNA replication at the chromosome origin. We discuss the possible roles of HBsu in replication initiation and other essential cellular functions.

Molecular detection of isoniazid monoresistance improves tuberculosis treatment: A retrospective cohort in France.

OBJECTIVES: Isoniazid-monoresistant tuberculosis (HR-TB) requires early diagnosis and adapted treatment to achieve optimal outcomes. The primary aim of the study was to assess the impact of the implementation of rapid diagnostic tests on HR-TB treatment in France. METHODS: We designed a retrospective multicentre study including consecutive HR-TB patients diagnosed in 2016 and 2017. Implementation of a molecular assay detecting isoniazid resistance directly on a clinical sample was recorded. The association between early implementation of such assays and adequate treatment was assessed by a multivariable Cox proportional hazards model. RESULTS: Overall, 99 HR-TB patients were included from 20 University Hospitals. Among all smear-positive HR-TB patients, only 26% beneficiated from early molecular HR detection. This detection was independently associated with shorter time to adequate treatment (HR = 2.0 [1.1-3.8], p = 0.03). CONCLUSION: In our study, molecular detection of HR on an initial sample was independently associated with earlier treatment adaptation.

Management of patients with pulmonary mycobacteriosis in France: a multicenter retrospective cohort study.

BACKGROUND: Recent studies report very low adherence of practitioners to ATS/IDSA recommendations for the treatment of nontuberculous mycobacteria pulmonary disease (NTM-PD), as well as a great variability of practices. Type of management could impact prognosis. METHODS: To evaluate management and prognosis of patients with NTM-PD cases with respect to ATS recommendations, we conducted a multicenter retrospective cohort study (18 sentinel sites distributed throughout France), over a period of six years. We collected clinical, radiological, microbiological characteristics, management and outcome of the patients (especially death or not). RESULTS: 477 patients with NTM-PD were included. Respiratory comorbidities were found in 68% of cases, tuberculosis sequelae in 31.4% of patients, and immunosuppression in 16.8% of cases. The three most common NTM species were Mycobacterium avium complex (60%), M. xenopi (20%) and M. kansasii (5.7%). Smear-positive was found in one third of NTM-PD. Nodulobronchiectatic forms were observed in 54.3% of cases, and cavitary forms in 19.1% of patients. Sixty-three percent of patients were treated, 72.4% of patients with smear-positive samples, and 57.5% of patients with smear-negative samples. Treatment was in adequacy with ATS guidelines in 73.5%. The 2-year mortality was 14.4%. In the Cox regression, treatment (HR = 0.51), age (HR = 1.02), and M. abscessus (3.19) appeared as the 3 significant independent prognostic factors. CONCLUSION: These findings highlight the adequacy between French practices and the ATS/IDSA guidelines. Treatment was associated with a better survival.

Case Report: Acquired Disseminated BCG in the Context of a Delayed Immune Reconstitution After Hematological Malignancy.

Context: Disseminated infections due to Mycobacterium bovis Bacillus Calmette-Guérin (BCG) are unusual and occur mostly in patients with inborn error of immunity (IEI) or acquired immunodeficiency. However, cases of secondary BCGosis due to intravesical BCG instillation have been described. Herein, we present a case of severe BCGosis occurring in an unusual situation. Case Description: We report one case of severe disseminated BCG disease occurring after hematological malignancy in a 48-year-old man without BCG instillation and previously vaccinated in infancy with no complication. Laboratory investigations demonstrated that he was not affected by any known or candidate gene of IEI or intrinsic cellular defect involving IFNγ pathway. Whole genome sequencing of the BCG strain showed that it was most closely related to the M. bovis BCG Tice strain, suggesting an unexpected relationship between the secondary immunodeficiency of the patient and the acquired BCG infection. Conclusion: This case highlights the fact that, in addition to the IEI, physicians, as well as microbiologists and pharmacists should be aware of possible acquired disseminated BCG disease in secondary immunocompromised patients treated in centers that administrate BCG for bladder cancers.

Isoniazid-monoresistant tuberculosis in France: Risk factors, treatment outcomes and adverse events.

OBJECTIVES: Isoniazid-monoresistant tuberculosis (HR-TB) is the most prevalent form of drug-resistant TB worldwide and in France and is associated with poorer treatment outcomes compared with drug-susceptible TB (DS-TB). The objective of this study was to determine the characteristics of HR-TB patients in France and to compare outcomes and safety of treatment for HR-TB and DS-TB. METHODS: We performed a case-control multicenter study to identify risk factors associated with HR-TB and compare treatment outcomes and safety between HR-TB patients and DS-TB patients. RESULTS: Characteristics of 99 HR-TB patients diagnosed and treated in the university hospitals of Paris, Lille, Caen and Strasbourg were compared with 99 DS-TB patients. Female sex (OR = 2.2; 1.0-4.7), birth in the West-Pacific World Health Organization region (OR = 4.6; 1.1-18.7) and resistance to streptomycin (OR = 77.5; 10.1-594.4) were found to be independently associated with HR-TB. Rates of treatment success did not differ significantly between HR-TB and DS-TB. CONCLUSIONS: Factors associated with HR-TB are not significant enough to efficiently screen TB patients at risk of HR-TB. The systematic implementation of rapid molecular testing on clinical samples remains the only effective way to make the early diagnosis of HR-TB and adapt treatment.

Volcanism and palaeoclimate change drive diversification of the world's largest whip spider (Amblypygi).

The tropics contain many of the most biodiverse regions on Earth but the processes responsible for generating this diversity remain poorly understood. This study investigated the drivers of diversification in arthropods with stenotopic ecological requirements and limited dispersal capability using as a model the monotypic whip spider (Amblypygi) genus Acanthophrynus, widespread in the tropical deciduous forests of Mexico. We hypothesized that for these organisms, the tropical deciduous forests serve as a conduit for dispersal, with their disappearance imposing barriers. Given that these forests are located in a region of complex geological history and that they fluctuated in extent during the Pliocene-Pleistocene glacial/interglacial cycles we combine molecular divergence dating, palaeoclimatic niche modelling and ancestral area reconstruction to test if and when habitat fragmentation promoted diversification in Acanthophrynus. Concomitant with the expected role of landscape change, we demonstrate that orogeny of the Trans-Mexican Volcanic Belt, in the Late Miocene or Early Pliocene (6.95-5.21 million years ago), drove the earliest divergence of Acanthophrynus by vicariance. Similarly, as expected, the later onset of glaciations strongly impacted diversification. Whereas a more stable climate in the southern part of the distribution enabled further diversification, a marked loss of suitable habitat during the glaciations only allowed dispersal and diversification in the north to occur later, resulting in a lower overall diversity in this region. Barriers and diversification patterns identified in Acanthophrynus are reflected in the phylogeography of codistributed vertebrates and arthropods, emphasizing the profound impact of Trans-Mexican Volcanic Belt orogeny and glacial/interglacial cycles as drivers of diversification in the Mexican Neotropics.

Revised version (INFD-D-20-00242): impact of 16S rDNA sequencing on clinical treatment decisions: a single center retrospective study.

BACKGROUND: PCRs targeting 16S ribosomal DNA (16S PCR) followed by Sanger's sequencing can identify bacteria from normally sterile sites and complement standard analyzes, but they are expensive. We conducted a retrospective study in the Strasbourg University Hospital to assess the clinical impact of 16S PCR sequencing on patients' treatments according to different sample types. METHODS: From 2014 to 2018, 806 16S PCR samples were processed, and 191 of those were positive. RESULTS: Overall, the test impacted the treatment of 62 of the 191 patients (32%). The antibiotic treatment was rationalized in 31 patients (50%) and extended in 24 patients (39%), and an invasive procedure was chosen for 7 patients (11%) due to the 16S PCR sequencing results. Positive 16S PCR sequencing results on cerebrospinal fluid (CSF) had a greater impact on patients' management than positive ones on cardiac valves (p = 0.044). The clinical impact of positive 16S PCR sequencing results were significantly higher when blood cultures were negative (p < 0.001), and this difference appeared larger when both blood and sample cultures were negative (p < 0.001). The diagnostic contribution of 16S PCR was higher in patients with previous antibiotic treatment (p < 0.001). CONCLUSION: In all, 16S PCR analysis has a significant clinical impact on patient management, particularly for suspected CSF infections, for patients with culture-negative samples and for those with previous antibiotic treatments.

Protein aggregation in bacteria.

Protein aggregation occurs as a consequence of perturbations in protein homeostasis that can be triggered by environmental and cellular stresses. The accumulation of protein aggregates has been associated with aging and other pathologies in eukaryotes, and in bacteria with changes in growth rate, stress resistance and virulence. Numerous past studies, mostly performed in Escherichia coli, have led to a detailed understanding of the functions of the bacterial protein quality control machinery in preventing and reversing protein aggregation. However, more recent research points toward unexpected diversity in how phylogenetically different bacteria utilize components of this machinery to cope with protein aggregation. Furthermore, how persistent protein aggregates localize and are passed on to progeny during cell division and how their presence impacts reproduction and the fitness of bacterial populations remains a controversial field of research. Finally, although protein aggregation is generally seen as a symptom of stress, recent work suggests that aggregation of specific proteins under certain conditions can regulate gene expression and cellular resource allocation. This review discusses recent advances in understanding the consequences of protein aggregation and how this process is dealt with in bacteria, with focus on highlighting the differences and similarities observed between phylogenetically different groups of bacteria.

Growth-driven displacement of protein aggregates along the cell length ensures partitioning to both daughter cells in Caulobacter crescentus.

All living cells must cope with protein aggregation, which occurs as a result of experiencing stress. In previously studied bacteria, aggregated protein is collected at the cell poles and is retained throughout consecutive cell divisions only in old pole-inheriting daughter cells, resulting in aggregation-free progeny within a few generations. In this study, we describe the in vivo kinetics of aggregate formation and elimination following heat and antibiotic stress in the asymmetrically dividing bacterium Caulobacter crescentus. Unexpectedly, in this bacterium, protein aggregates form as multiple distributed foci located throughout the cell volume. Time-lapse microscopy revealed that under moderate stress, the majority of these protein aggregates are short-lived and rapidly dissolved by the major chaperone DnaK and the disaggregase ClpB. Severe stress or genetic perturbation of the protein quality control machinery induces the formation of long-lived aggregates. Importantly, the majority of persistent aggregates neither collect at the cell poles nor are they partitioned to only one daughter cell type. Instead, we show that aggregates are distributed to both daughter cells in the same ratio at each division, which is driven by the continuous elongation of the growing mother cell. Therefore, our study has revealed a new pattern of protein aggregate inheritance in bacteria.

Dissociating effect of salivary gland extract from Ixodes ricinus on human fibroblasts: Potential impact on Borrelia transmission.

Understanding the mechanism of pathogen transmission is essential for the development of strategies to reduce arthropod-borne diseases. The pharmaco- and immunomodulatory properties of insect and acarine saliva play an essential role in the efficiency of pathogen transmission. The skin as the site where arthropod saliva and pathogens are inoculated - represents the key interface in vector-borne diseases. We identified tick molecules potentially involved in pathogen transmission, using micro-HPLC and mass spectrometry, followed by in vitro assays on human skin cells. Histone H4 isolated from Ixodes ricinus salivary gland extract was identified as a molecule with a dissociating effect on human primary fibroblasts. This histone might be involved in the formation of the feeding pool formed around the tick mouthparts and responsible of tissue necrosis in the vertebrate host. Thanks to its selective antimicrobial activity, it may also sterilize the feeding pool and facilitate transmission of pathogens such as Borrelia burgdorferi sensu lato.

Description of a new Charinus species (Amblypygi: Charinidae) from the Monseñor Nouel province, Dominican Republic.

A new species of Charinus Simon, 1892 from the Dominican Republic is described. With the addition of Charinus magua sp. nov. from the Monseñor Nouel province, the number of known members of the genus Charinus occurring on the island Hispaniola is increased to three. The frontal process, the trichobothria on leg IV, the number and shape of the articles of leg I and the shape of the tarsomers of legs II-IV are often included in taxonomical descriptions of Charinus species. We present these characters in the detailed description of C. magua sp. nov. and illustrate these for the first time for the two other known Charinus from Hispaniola, Charinus dominicanus and Charinus bahoruco. Furthermore, we present and discuss the cerotegument ultrastructure of all three species.