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Author(s): Jérôme Legoff [1, 2]; Matthieu Resche-Rigon [3]; Jerome Bouquet [2, 4]; Marie Robin [5]; Samia N Naccache [2, 4]; Séverine Mercier-Delarue [1]; Scot Federman [2, 4]; Erik Samayoa [2, [...]

In order to adapt to changing environments, bacteria have evolved two-component systems (TCSs) that are able to sense and respond to environmental stimuli. The signal perception relies on a sensor protein whose activation allows rapid adaptation through transcriptional regulation achieved by the regulatory protein. The ability to adhere to and grow on the surface of human host cells is an absolute requirement for many pathogens, including Neisseria meningitidis, in order to colonize new hosts and to disseminate inside their host. Among the four TCSs encoded in the meningococcus genome, only the PhoQ (MisS)/PhoP (MisR) system has been shown to constitute a functional signal transduction circuit. To investigate the involvement of this TCS in the adaptation process requisite for host cell colonization, we have tested the ability to grow on host cells of a mutant inactivated for the sensor of the TCS. Our results demonstrate the involvement of the TCS in the adaptation of the meningococcus to growth on host cells. We show that the expression of the PhoQ (MisS)/PhoP (MisR) TCS is cell-contact controlled. Furthermore, this TCS controls the regulation of a group of genes, the REP2 regulon, previously shown to be cellcontact regulated and to encode functions crucial for the adaptation of the bacterium to host cell colonization. Thus, we provide evidence that one of the four TCSs existing in N. meningitidis contributes to the adaptation of the pathogen to growth on host cells.

Background Mycoplasma genitalium (MG) is an emerging pathogen among men who have sex with men (MSM) with raising rates of antibiotic resistance. This study assessed the prevalence and incidence of MG infection in MSM enrolled in the open-label phase of the ANRS IPERGAY trial with on-demand tenofovir disoproxil fumarate/emtricitabine for human immunodeficiency virus prevention and the impact of doxycycline post-exposure prophylaxis (PEP). Methods 210 subjects were tested at baseline and at 6 months by real-time PCR assays for MG detection in urine samples and oropharyngeal and anal swabs. Resistance to azithromycin (AZM), to fluoroquinolones (FQs), and to doxycycline was investigated in the French National Reference Center of Bacterial Sexually Transmitted Infections (STIs). Results The all-site prevalence of MG at baseline was 10.5% (6.3% in urine samples, 4.3% in anal swabs, 0.5% in throat swabs) and remained unchanged at 6 months whether or not PEP was used: 9.9% overall, 10.2% with PEP, 9.6% without. The overall rate of MG resistance (prevalent and incident cases) to AZM and FQs was 67.6% and 9.1%, respectively, with no difference between arms. An in vivo mutation of the MG 16S rRNA, which could be associated with tetracycline resistance, was observed in 12.5% of specimens tested. Conclusions The prevalence of MG infection among MSM on pre-exposure prophylaxis was high and its incidence was not decreased by doxycycline prophylaxis with a similar high rate of AZM and FQ resistance, raising challenging issues for the treatment of this STI and supporting current recommendations to avoid testing or treatment of asymptomatic MG infection. [ABSTRACT FROM AUTHOR]

Aim: Very preterm birth is associated with a high risk of enteropathies. Diagnosis is challenging, especially in mild forms, leading to unnecessary periods of cessation of enteral feeding. This study aimed at establishing a prognosis score of enteropathy combining clinical parameters and faecal calprotectin concentration. Methods: This prospective multicentric study included preterm neonates born at a gestational age of 33 weeks or less. Stools were collected weekly until hospital discharge, and daily in case of digestive events for calprotectin measurement (ELISA and immunochromatography) and microbiota analyses (16S rRNA gene sequencing). Results: Among the 121 neonates included, 21 experienced at least one episode of enteropathy, mainly mild forms. By ELISA testing, median faecal calprotectin was 88 (8‐798) µg/g faeces. No statistically significant association was found between the outset of enteropathy and maternal and neonatal characteristics, and calprotectin levels. The agreement between ELISA and immunochromatography assay was moderate (intra‐class correlation coefficient 0.58, 95%CI [0.47‐0.66]). Comparison of species diversity and relative bacterial abundance profiles between infants with or without enteropathy revealed no specific alterations associated with enteropathy. Conclusion: The study failed to propose a prognostic score of enteropathy, probably due the large inter‐ and intra‐individual variability of faecal calprotectin in very preterm neonates. [ABSTRACT FROM AUTHOR]

Folliculitis decalvans (FD) is a chronic inflammatory disease of unknown aetiology. Although Staphylococcus aureus, frequently found on lesional skin, is thought to play a causal role, the importance of its involvement remains controversial. To examine the role of S aureus, we compared superficial and subepidermal microbiota in 20 FD patients who had S aureus on lesional skin and in 20 healthy controls using culture techniques and genomic identification, before and after an anti‐staphylococcal treatment; we also screened for S aureus virulence factors. When present on lesional skin, S aureus colonized non‐lesional and subepidermal skin in 80% of cases. These data imply a break in the epidermal barrier integrity and that an abnormal non‐lesional skin microbiota persists in FD. S aureus had no superantigenic toxin in 31% of cases and no toxin specificity. Clinical improvement obtained in most cases upon treatment was associated with the disappearance of S aureus in all studied areas, with an incomplete restoration of normal microbiota and a significant increase in negative bacterial samples. This persistent unbalanced, subepidermal microbiota may act as a reservoir of abnormal flora and explain the chronicity of FD, suggesting new avenues of research to restore normal microbiota. [ABSTRACT FROM AUTHOR]

Type IV pili are crucial for the virulence of Neisseria meningitidis. PilC proteins belong to the complex protein machinery required for pili biosynthesis. The expression of the pilC1 gene is known to be induced during host cell contact and to be tightly controlled through four promoters, two transcription factors and a two-component signal transduction system. By screening of an insertional-mutant library, we identified a novel regulatory protein, i.e. NMA1805, involved in the pilC1 complex regulation. Increased transcription of gene NMA1805 was shown to result in augmented expression of the pilC1 gene, whereas abrogated expression of gene NMA1805 was associated with an absence of pilC1 induction upon contact with host cells. Moreover, we demonstrated that the NMA1805 gene displayed two promoters. The NMA1805 regulatory protein was evidenced to interact with one of them. [ABSTRACT FROM AUTHOR]

We report the first case of chancroid seen at our clinic in 14 years. It was diagnosed by nuclear acid amplification test in a male patient returning from Madagascar. Although the disease is considered on the verge of disappearance even in tropical countries, its real potential for reemergence - due to new strains of Haemophilus ducreyi, underreporting and a lack of widespread use of molecular testing - could be underestimated. [ABSTRACT FROM AUTHOR]