EEF2-inactivating toxins engage the NLRP1 inflammasome and promote epithelial barrier disruption

Human airway and corneal epithelial cells, which are critically altered during chronic infections mediated by Pseudomonas aeruginosa, specifically express the inflammasome sensor NLRP1. Here, together with a companion study, we report that the NLRP1 inflammasome detects exotoxin A (EXOA), a ribotoxin released by P. aeruginosa type 2 secretion system (T2SS), during chronic infection. Mechanistically, EXOA-driven eukaryotic elongation factor 2 (EEF2) ribosylation and covalent inactivation promote ribotoxic stress and subsequent NLRP1 inflammasome activation, a process shared with other EEF2-inactivating toxins, diphtheria toxin and cholix toxin. Biochemically, irreversible EEF2 inactivation triggers ribosome stress-associated kinases ZAKα- and P38-dependent NLRP1 phosphorylation and subsequent proteasome-driven functional degradation. Finally, cystic fibrosis cells from patients exhibit exacerbated P38 activity and hypersensitivity to EXOA-induced ribotoxic stress-dependent NLRP1 inflammasome activation, a process inhibited by the use of ZAKα inhibitors. Altogether, our results show the importance of P. aeruginosa virulence factor EXOA at promoting NLRP1-dependent epithelial damage and identify ZAKα as a critical sensor of virulence-inactivated EEF2.

Genetic Diversity and Population Structure of Mycobacterium bovis at the Human-Animal-Ecosystem Interface in France: “A One Health Approach”

Mycobacterium bovis infects cattle and wildlife, and also causes a small proportion of tuberculosis cases in humans. In most European countries, M. bovis infections in cattle have been drastically reduced, but not eradicated. Here, to determine the M. bovis circulation within and between the human, cattle, and wildlife compartments, we characterized by spoligotyping and mycobacterial interspersed repetitive unit-variable number tandem repeat (MIRU-VNTR) typing the genetic diversity of M. bovis isolates collected from humans, cattle, and wildlife in France from 2000 to 2010. We also assessed their genetic structure within and among the different host groups, and across time and space. The M. bovis genetic structure and its spatiotemporal variations showed different dynamics in the human and animal compartments. Most genotypes detected in human isolates were absent in cattle and wildlife isolates, possibly because in patients, M. bovis infection was contracted abroad or was the reactivation of an old lesion. Therefore, they did not match the genetic pool present in France during the study period. However, some human-cattle exchanges occurred because some genotypes were common to both compartments. This study provides new elements for understanding M. bovis epidemiology in France, and calls for increased efforts to control this pathogen worldwide.

Rifampin-moxifloxacin-metronidazole combination therapy for severe Hurley stage 1 hidradenitis suppurativa: prospective short-term trial and 1-year follow-up in 28 consecutive patients

BACKGROUND

Severe Hurley stage 1 hidradenitis suppurativa (HS1) is a difficult-to-treat form of the disease.

OBJECTIVE

To assess the efficacy and tolerance of the oral combination of rifampin (10 mg/kg once daily)/moxifloxacin (400 mg once daily)/metronidazole (250-500 mg 3 times daily) (RMoM) treatment strategy in patients with severe HS1.

METHODS

Prospective, open-label, noncomparative cohort study in 28 consecutive patients. Nineteen patients were treated for 6 weeks by RMoM, followed by 4 weeks of rifampin/moxifloxacin alone, then by cotrimoxazole after remission. Moxifloxacin was replaced by pristinamycin (1 g 3 times daily) in 9 patients because of contraindications or intolerance. The primary endpoint was a Sartorius score of 0 (clinical remission) at week 12.

RESULTS

The median Sartorius score dropped from 14 to 0 (P = 6 × 10^-6) at week 12, with 75% of patients reaching clinical remission. A low initial Sartorius score was a prognosis factor for clinical remission (P = .049). The main adverse effects were mild gastrointestinal discomfort, mucosal candidiasis, and asthenia. At 1 year of follow-up, the median number of flares dropped from 21/year to 1 (P = 1 × 10^-5).

LIMITATIONS

Small, monocentric, noncontrolled study.

CONCLUSIONS

Complete and prolonged remission can be obtained in severe HS1 by using targeted antimicrobial treatments.

In Vitro Antimicrobial Susceptibility Profiles of Gram-Positive Anaerobic Cocci Responsible for Human Invasive Infections

The aim of this multicentre study was to determine the in vitro susceptibility to anti-anaerobic antibiotics of Gram-positive anaerobic cocci (GPAC) isolates responsible for invasive infections in humans. A total of 133 GPAC isolates were collected in nine French hospitals from 2016 to 2020. All strains were identified to the species level (MALDI-TOF mass spectrometry, 16S rRNA sequencing). Minimum inhibitory concentrations (MICs) of amoxicillin, piperacillin, cefotaxime, imipenem, clindamycin, vancomycin, linezolid, moxifloxacin, rifampicin, and metronidazole were determined by the reference agar dilution method. Main erm-like genes were detected by PCR. The 133 GPAC isolates were identified as follows: 10 Anaerococcus spp., 49 Finegoldia magna, 33 Parvimonas micra, 30 Peptoniphilus spp., and 11 Peptostreptococcus anaerobius. All isolates were susceptible to imipenem, vancomycin (except 3 P. micra), linezolid and metronidazole. All isolates were susceptible to amoxicillin and piperacillin, except for P. anaerobius (54% and 45% susceptibility only, respectively). MICs of cefotaxime widely varied while activity of rifampicin, and moxifloxacin was also variable. Concerning clindamycin, 31 were categorized as resistant (22 erm(A) subclass erm(TR), 7 erm(B), 1 both genes and 1 negative for tested erm genes) with MICs from 8 to >32 mg/L. Although GPACs are usually susceptible to drugs commonly used for the treatment of anaerobic infections, antimicrobial susceptibility should be evaluated in vitro.

Management of initial colonisations with Burkholderia species in France, with retrospective analysis in five cystic fibrosis Centres: a pilot study

Background

Whereas Burkholderia infections are recognized to impair prognosis in cystic fibrosis (CF) patients, there is no recommendation to date for early eradication therapy. The aim of our study was to analyse the current management of initial colonisations with Burkholderia cepacia complex (BCC) or B. gladioli in French CF Centres and its impact on bacterial clearance and clinical outcome.

Methods

We performed a retrospective review of the primary colonisations (PC), defined as newly positive sputum cultures, observed between 2010 and 2018 in five CF Centres. Treatment regimens, microbiological and clinical data were collected.

Results

Seventeen patients (14 with BCC, and 3 with B. gladioli) were included. Eradication therapy, using heterogeneous combinations of intravenous, oral or nebulised antibiotics, was attempted in 11 patients. Six out of the 11 treated patients, and 4 out of the 6 untreated patients cleared the bacterium. Though not statistically significant, higher forced expiratory volume in 1 second and forced vital capacity at PC and consistency of treatment with in vitro antibiotic susceptibility tended to be associated with eradication. The management of PC was shown to be heterogeneous, thus impairing the statistical power of our study. Large prospective studies are needed to define whom to treat, when, and how.

Conclusions

Pending these studies, we propose, due to possible spontaneous clearance, to check the presence of Burkholderia 1 month after PC before starting antibiotics, at least in the milder cases, and to evaluate a combination of intravenous beta-lactam + oral or intravenous fluoroquinolone + inhaled aminoglycoside.

Safety of Pyrazinamide for the Treatment of Tuberculosis in Older Patients Over 75 Years of Age: A Retrospective Monocentric Cohort Study

OBJECTIVES

Pyrazinamide (PZA) has a controversial safety profile in older patients. We aimed to assess the frequency and risk factors for adverse drug reactions (ADRs) in patients over 75 years of age treated for tuberculosis with or without PZA.

METHODS

We conducted a retrospective monocentric study including patients aged over 75 years treated for active tuberculosis between 2008 and 2018. The frequency, type, seriousness, and causality assessment of ADRs to anti-tuberculosis treatment were compared between patients receiving PZA or not. Risk factors for ADRs were investigated using univariable and multivariable analyses by logistic regression.

RESULTS

Among the 110 patients included, 54 (49.1%) received PZA (group 1) and 56 (50.9%) did not (group 2). ADRs to anti-tuberculosis drugs occurred in 31 patients (57.4%) in groups 1 and 15 (26.8%) in group 2 (p = 0.003). PZA-related ADRs occurred in 40.7% of exposed patients. Frequency of renal ADRs was higher in group 1 (9.3% vs 0%; p = 0.026). Rates of hepatic (18.5% vs 12.5%; p = 0.38), digestive (22.2% vs 8.9%; p = 0.054), and allergic (14.8% vs 5.4%; p = 0.12) ADRs were numerically higher in group 1 although the differences were not statistically significant. Serious ADRs occurred more frequently in group 1 (24.1% vs 8.9%; p = 0.03). The use of PZA was the only independent risk factor for ADRs to anti-tuberculosis drugs (odds ratio 3.75, 95% CI 1.5-9.6; p = 0.0056). No risk factors for PZA-related ADRs were identified.

CONCLUSION

In older French patients, the use of PZA was associated with more frequent ADRs to anti-tuberculosis drugs.

Evaluation of the GenoType NTM-DR assay performance for the identification and molecular detection of antibiotic resistance in Mycobacterium abscessus complex

The first objective of this study was to determine the GenoType NTM-DR assay performance for subspecies identification in Mycobacterium abscessus complex isolates. The second objective was to evaluate the GenoType NTM-DR assay ability to detect clarithromycin and amikacin resistance in M. abscessus complex isolates compared with drug susceptibility testing (DST) and PCR sequencing of the erm(41), rrl and rrs genes. The concordance between the GenoType NTM-DR and MLST results concerning subspecies identification was 100%. The wild type and mutated alleles of the rrl and rrs genes were detected by the GenoType NTM-DR assay and PCR sequencing with 100% (115/115) agreement. Similarly, 100% concordance between GenoType NTM-DR and DST was observed for clarithromycin and amikacin testing. Sensitivity for the detection of clarithromycin and amikacin resistance was 100%. The GenoType NTM-DR assay provides a robust and complementary tool to the gold standard methods (MLST and broth microdilution) for subspecies identification and drug resistance detection.

[Skin microbiome: role in human health and skin inflammatory diseases]

Skin microbiome: role in human health and skin inflammatory diseases. The skin barrier is a major interface between the human host and its environment. It is colonized by more than 1000 different bacterial species which live at the skin surface or within skin appendages but also of by fungi, virus and mites. In adults, the most abundant bacterial genera are Cutibacterium, Corynebacterium and coagulase negative staphylococci. The composition of the skin microbiome mostly varies according to localization, reflecting different physical, chemical and environmental conditions. Despite constant environmental exposure, the skin microbiome of adults is stable over time. Coagulase negative staphylococci play an important role in skin defense by preventing colonization by pathogens such as Staphylococcus aureus and Streptococcus pyogenes, demonstrating mutualistic relationships with the human host. Skin inflammatory diseases are associated with specific dysbiotic features that probably play an important role in their pathophysiology and may be treatment targets in the future.

Nontuberculous lymphadenitis in children: What management strategy?

OBJECTIVES

Nontuberculous mycobacterial (NTM) lymphadenitis is a rare disease of children under 5 years. Its treatment is not standardized, even a "wait-and-see" approach is shown to be effective in the literature. Here, we discuss the diagnostic and therapeutic strategies employed in our departments.

METHODS

Records of pediatric patients treated for NTM cervical lymphadenitis from 2010 to 2015 in our tertiary center were retrospectively reviewed. Patients underwent cervical echotomography and/or CT scan. Every patient but one had microbiological explorations (NTM polymerase chain reaction [PCR] and culture) on fine needle aspiration of pus and/or adenitis biopsy. Differential diagnoses (tuberculosis, cat scratch disease) were excluded with serologies, chest X-Ray, and PCR on adenitis samples. Patients were classified as "proven diagnosis" (NTM detected), "highly probable" (suggestive clinical and anatomopathological aspect) or "possible" infection (suggestive adenitis alone). Treatments, follow-up and adverse events were reviewed.

RESULTS

Thirty-one patients were treated for NTM, median age 2.40 years (Interquartile Range IQR = [1.85-3.16]). Twenty-nine patients (96.77%) had an isolated cervico-facial localization. Median follow-up was 8.00 months (IQR = [4.20-13.43]). We found 17 "proven diagnosis" (58.62%), 5 "highly probable" (17.24%) and 7 "possible" infections (24.14%). "Proven" infections were due to: Mycobacterium avium (n = 12, 66.67%) and M. intracellulare (n = 5, 27.78%). All 29 patients received antibiotics, which were effective for 10 (34.48%, group 1); 10 underwent surgical excision for a poor outcome with antibiotics (34.48%, group 2); spontaneous or surgical drainage occurred in 9 on antibiotics (31.03%, group 3). The median times to resolution for group 1, 2 and 3 were respectively 6.33 months, 6.22 months and 9.53 months. Antibiotics treatment was mostly clarithromycin (n = 27, 93.10%) and/or rifampicin (n = 19, 65.52%); 18 patients (62.07%) received both. Median antibiotics duration was 6.23 months (IQR = [5.17-7.46]), with good compliance (79.31%). The observed adverse effects were 3 (13.04%) isolated transient transaminase elevations, 1 case (4.35%) of minor creatinine elevation, and 1 case (4.35%) of transient diarrhea. Surgical drainage caused 1 transient marginal mandibular nerve palsy, resolutive after 1 month.

CONCLUSION

Antibiotics in NTM adenitis lead to resolution in 7 months, with good tolerance and compliance. The efficacy of "wait-and-see" attitude in the literature make excision surgery a second line treatment.

The Microbiological Landscape of Anaerobic Infections in Hidradenitis Suppurativa: A Prospective Metagenomic Study

Background

Hidradenitis suppurativa (HS) is a frequent and severe disease of the skin, characterized by recurrent or chronic skinfold suppurative lesions with a high impact on quality of life. Although considered inflammatory, antimicrobial treatments can improve or lead to clinical remission of HS, suggesting triggering microbial factors. Indeed, mixed anaerobic microbiota are associated with a majority of HS lesions. Our aim in this study was to characterize the landscape of anaerobic infections in HS using high-throughput sequencing.

Methods

We sampled and cultured 149 lesions and 175 unaffected control skinfold areas from 65 adult HS patients. The microbiome of 80 anaerobic lesions was compared to that of 88 control samples by 454 high-throughput sequencing after construction of 16S ribosomal RNA gene libraries.

Results

Bacterial cultures detected anaerobes in 83% of lesions vs 53% of control samples, combined with milleri group streptococci and actinomycetes in 33% and 26% of cases, respectively. High-throughput sequencing identified 43 taxa associated with HS lesions. Two gram-negative anaerobic rod taxa, Prevotella and Porphyromonas, predominated, contrasting with a reduced abundance of aerobic commensals. These rare taxa of normal skinfold microbiota were associated with lesions independently of gender, duration and familial history of HS, body mass index, and location. Two main additional taxa, Fusobacterium and Parvimonas, correlated with the clinical severity of HS.

Conclusions

In this study we reveal the high prevalence and particular landscape of mixed anaerobic infection in HS, paving the way for rationale targeted antimicrobial treatments.

Enhanced culture recovery of Campylobacter with modified Cary-Blair medium: A practical field experience

Modified Cary-Blair medium derived devices have been implemented in many laboratories to optimize culture recovery of common bacterial enteric pathogens. Our analysis constitutes the first report of routine laboratory experience supporting the idea that the use of such devices enhances Campylobacter recovery from stools.

Bacterial pathogens associated with hidradenitis suppurativa, France

Hidradenitis suppurativa (HS) is a skin disease characterized by recurrent nodules or abscesses and chronic suppurating lesions. In the absence of clear pathophysiology, HS is considered to be an inflammatory disease and has no satisfactory medical treatment. Recently, prolonged antimicrobial treatments were shown to improve or resolve HS lesions. We prospectively studied the microbiology of 102 HS lesions sampled from 82 patients using prolonged bacterial cultures and bacterial metagenomics on 6 samples. Staphylococcus lugdunensis was cultured as a unique or predominant isolate from 58% of HS nodules and abscesses, and a polymicrobial anaerobic microflora comprising strict anaerobes, milleri group streptococci, and actinomycetes was found in 24% of abscesses or nodules and in 87% of chronic suppurating lesions. These data show that bacteria known to cause soft tissue and skin infections are associated with HS lesions. Whether these pathogens are the cause of the lesions or are secondary infectious agents, these findings support targeted antimicrobial treatment of HS.

Bacteriology of hidradenitis suppurativa/acne inversa: A review

Given that follicular papules and pustules, as well as nodules and abscesses, are the clinical hallmarks of hidradenitis suppurativa (HS), an infectious, bacterial pathway has been suspected in the pathogenesis of this chronic, inflammatory condition. Elucidating the behavior and role of bacterial species in HS and their interaction with cutaneous innate immunity will provide more insight into the pathophysiology of this condition. This review of prospective investigations suggests a synergistic relationship between impaired innate immunity and microbial factors in the etiology of HS.

Efficacy of ertapenem in severe hidradenitis suppurativa: a pilot study in a cohort of 30 consecutive patients

OBJECTIVES

Hidradenitis suppurativa (HS) is an inflammatory skin disease typically localized in the axillae and inguinal and perineal areas. In the absence of standardized medical treatment, severe HS patients present chronic suppurative lesions with polymicrobial anaerobic abscesses. Wide surgery is the cornerstone treatment of severe HS, but surgical indications are limited by the extent of lesions. Intravenous broad-spectrum antibiotics may help control HS, but their efficacy is not documented. This study was designed to assess the efficacy of a 6 week course of ertapenem (1 g daily) and of antibiotic consolidation treatments for 6 months (M6) in severe HS.

PATIENTS AND METHODS

Thirty consecutive patients with severe HS were retrospectively included in this study. The clinical severity of HS was assessed using the Sartorius score, which takes into account the number and severity of lesions.

RESULTS

The median (IQR) Sartorius score dropped from 49.5 (28-62) at baseline to 19.0 (12-28) after ertapenem (P < 10(-4)). Five patients were lost to follow-up thereafter. At M6 the Sartorius score further decreased for the 16 patients who received continuous consolidation treatments, since 59% of HS areas reached clinical remission at M6 (i.e. absence of any inflammatory symptoms, P < 10(-4)). Nine patients interrupted or received intermittent consolidation treatments due to poor observance or irregular follow-up. Their Sartorius score stopped improving or returned to baseline. No major adverse event occurred.

CONCLUSIONS

Ertapenem can dramatically improve severe HS. Consolidation treatments are needed to further improve HS and are mandatory to prevent relapses. Combined with surgery, optimized antibiotic treatments may be promising in severe HS.

Efficacy of rifampin-moxifloxacin-metronidazole combination therapy in hidradenitis suppurativa

BACKGROUND

Antibiotics have been shown to improve hidradenitis suppurativa (HS) patients but complete remission is rare using these treatments.

OBJECTIVE

To assess the efficacy and safety of a combination of oral rifampin, moxifloxacin and metronidazole in long-lasting refractory HS.

METHODS

We retrospectively studied 28 consecutive HS patients including 6, 10 and 12 Hurley stage 1, 2 and 3 patients, respectively. Complete remission, defined as a clearance of all inflammatory lesions including hypertrophic scars, was the main outcome criterion of the study.

RESULTS

Complete remission was obtained in 16 patients, including 6/6, 8/10 and 2/12 patients with Hurley stage 1, 2 and 3, respectively (p=0.0004). The median duration of treatment to obtain complete remission was 2.4 (range 0.9-6.5) and 3.8 months (range 1.6-7.4) in stage 1 and 2 patients, respectively, and 6.2 and 12 months in the 2 stage 3 patients. Main adverse events of the treatments were gastrointestinal disorders (64% of patients) and vaginal candidiasis (35% of females). Reversible tendinopathy and hepatitis occurred in 4 and 1 patient, respectively.

CONCLUSIONS

Complete remission of refractory HS can be obtained using broad-spectrum antibiotics and Hurley staging is a prognostic factor of response to the treatment.

The Listeria transcriptional landscape from saprophytism to virulence

The bacterium Listeria monocytogenes is ubiquitous in the environment and can lead to severe food-borne infections. It has recently emerged as a multifaceted model in pathogenesis. However, how this bacterium switches from a saprophyte to a pathogen is largely unknown. Here, using tiling arrays and RNAs from wild-type and mutant bacteria grown in vitro, ex vivo and in vivo, we have analysed the transcription of its entire genome. We provide the complete Listeria operon map and have uncovered far more diverse types of RNAs than expected: in addition to 50 small RNAs (<500 nucleotides), at least two of which are involved in virulence in mice, we have identified antisense RNAs covering several open-reading frames and long overlapping 5' and 3' untranslated regions. We discovered that riboswitches can act as terminators for upstream genes. When Listeria reaches the host intestinal lumen, an extensive transcriptional reshaping occurs with a SigB-mediated activation of virulence genes. In contrast, in the blood, PrfA controls transcription of virulence genes. Remarkably, several non-coding RNAs absent in the non-pathogenic species Listeria innocua exhibit the same expression patterns as the virulence genes. Together, our data unravel successive and coordinated global transcriptional changes during infection and point to previously unknown regulatory mechanisms in bacteria.