The minor pilin PilV provides a conserved adhesion site throughout the antigenically variable meningococcal type IV pilus.

Neisseria meningitidis utilizes type IV pili (T4P) to adhere to and colonize host endothelial cells, a process at the heart of meningococcal invasive diseases leading to meningitis and sepsis. T4P are polymers of an antigenically variable major pilin building block, PilE, plus several core minor pilins that initiate pilus assembly and are thought to be located at the pilus tip. Adhesion of N. meningitidis to human endothelial cells requires both PilE and a conserved noncore minor pilin PilV, but the localization of PilV and its precise role in this process remains to be clarified. Here, we show that both PilE and PilV promote adhesion to endothelial vessels in vivo. The substantial adhesion defect observed for pilV mutants suggests it is the main adhesin. Consistent with this observation, superresolution microscopy showed the abundant distribution of PilV throughout the pilus. We determined the crystal structure of PilV and modeled it within the pilus filament. The small size of PilV causes it to be recessed relative to adjacent PilE subunits, which are dominated by a prominent hypervariable loop. Nonetheless, we identified a conserved surface-exposed adhesive loop on PilV by alanine scanning mutagenesis. Critically, antibodies directed against PilV inhibit N. meningitidis colonization of human skin grafts. These findings explain how N. meningitidis T4P undergo antigenic variation to evade the humoral immune response while maintaining their adhesive function and establish the potential of this highly conserved minor pilin as a vaccine and therapeutic target for the prevention and treatment of N. meningitidis infections.

Surgical site infection after pelvic bone and soft tissue sarcoma resection: Risk factors, microbiology, and impact of extended postoperative antibiotic prophylaxis.

BACKGROUND: Pelvic bone and/or soft tissue sarcoma removal surgeries are associated with a high rate of surgical site infection (SSI). The recommended antibiotic prophylaxis (ABP) duration is 24-48 h. We aimed to assess the impact of extended ABP (5 days) on the SSI rate and describe the microbiology of SSI in bone and/or soft tissue pelvic sarcomas. METHODS: We retrospectively included all consecutive patients who underwent pelvic bone and/or soft tissue sarcoma removal surgery between January 2010 and June 2020. RESULTS: We analyzed 146 patients with pelvic bone (45, 31%) or soft tissue (101, 69%). Sixty patients (41%) developed SSI. SSI occurred in 13/28 (46.4%) in the extended ABP group versus 47/118 (39.8%) in the standard group (p = 0.53). In multivariable analysis, risk factors for SSI were surgery duration (OR: 1.94 [1.41-2.92] per h), stay in postoperative ICU for more than 2 days (12.0 [2.8-61.3]), and shred or autologous skin flap (39.3 [5.8-409.5]). Extended ABP was not associated with SSI. SSI were mainly polymicrobial with Enterobacterales (57.4%) and Enterococcus (45%). CONCLUSIONS AND DISCUSSION: Pelvic bone and/or soft tissue sarcoma removal surgery is highly prone to postoperative infection. Extending the ABP to 5 days does not reduce the level of SSI.

Oral levofloxacin: population pharmacokinetics model and pharmacodynamics study in bone and joint infections.

OBJECTIVES: This study aimed at characterizing the pharmacokinetics (PK) of oral levofloxacin in adult patients in order to optimize dosing scheme and explore the PK/pharmacodynamics (PD) of levofloxacin in bone and joint infections (BJIs). METHODS: From November 2015 to December 2019, all patients hospitalized in Cochin Hospital, treated with levofloxacin and who had at least one dosage for therapeutic drug monitoring were included. PK was described using non-linear mixed-effect modelling. In a subgroup of patients with BJIs, the association between PK, MIC for the isolated pathogen and clinical outcome was investigated. Monte Carlo simulations investigated dosing regimens to achieve the PK/PD target (AUC/MIC ratio >100). RESULTS: One hundred and two patients were included (199 measurements), including 32 treated for BJI. A one-compartment model with first-order absorption and elimination best described the data. Effects of estimated creatinine clearance (eCLCR) and age were significant on levofloxacin clearance. In BJI patients, no significant association was found between levofloxacin PK/microbiological parameters and either clinical outcome or adverse events. Based on our model, we proposed optimized oral levofloxacin dosing regimens according to renal function, to reach the PK/PD target AUC/MIC ratio >100 for three frequent causative pathogens (Staphylococcus aureus, Enterobacterales and Pseudomonas aeruginosa). CONCLUSIONS: Our results reinforce the need of determining the MIC and using therapeutic drug monitoring in complex infections caused by P. aeruginosa.

Capnocytophaga zoonotic infections: a 10-year retrospective study (the French CANCAN study).

Zoonotic species of Capnocytophaga genus belong to the oral microbiota of dogs and cats. They may be responsible for serious human infections, mainly after animal bites, with a high mortality rate. In France, only few cases have been reported and no multicenter study has been conducted. Our aim was to describe the French epidemiology of Capnocytophaga zoonosis. We conducted a multicenter (21 centers) retrospective non-interventional, observational study in France describing the epidemiology of Capnocytophaga zoonosis (C. canimorsus, C. cynodegmi, C. canis) over 10 years with regard to clinical and bacteriological data. From 2009 to 2018, 44 cases of Capnocytophaga zoonotic infections were described (C. canimorsus, n = 41; C. cynodegmi, n = 3). We observed an increase (2.5 times) in the number of cases over the study period (from the first to the last 5 years of the study). The most frequent clinical presentations were sepsis (n = 37), skin and soft tissue infections (n = 12), meningitis (n = 8), osteoarticular infections (n = 6), and endocarditis (n = 2). About one-third of patients with sepsis went into septic shock. Mortality rate was 11%. Mortality and meningitis rates were significantly higher for alcoholic patients (p = 0.044 and p = 0.006, respectively). Other comorbidities included smoking, splenectomy, diabetes mellitus, and immunosuppressive therapy are associated to zoonotic Capnocytophaga infection. Eighty-two percent of cases involved contact with dogs, mostly included bites (63%). Despite all isolates were susceptible to the amoxicillin-clavulanic acid combination, three of them were resistant to amoxicillin.

The Impact of Surgical Strategy and Rifampin on Treatment Outcome in Cutibacterium Periprosthetic Joint Infections.

BACKGROUND: Cutibacterium species are common pathogens in periprosthetic joint infections (PJI). These infections are often treated with ß-lactams or clindamycin as monotherapy, or in combination with rifampin. Clinical evidence supporting the value of adding rifampin for treatment of Cutibacterium PJI is lacking. METHODS: In this multicenter retrospective study, we evaluated patients with Cutibacterium PJI and a minimal follow-up of 12 months. The primary endpoint was clinical success, defined by the absence of infection relapse or new infection. We used Fisher's exact tests and Cox proportional hazards models to analyze the effect of rifampin and other factors on clinical success after PJI. RESULTS: We included 187 patients (72.2% male, median age 67 years) with a median follow-up of 36 months. The surgical intervention was a 2-stage exchange in 95 (50.8%), 1-stage exchange in 51 (27.3%), debridement and implant retention (DAIR) in 34 (18.2%), and explantation without reimplantation in 7 (3.7%) patients. Rifampin was included in the antibiotic regimen in 81 (43.3%) cases. Infection relapse occurred in 28 (15.0%), and new infection in 13 (7.0%) cases. In the time-to-event analysis, DAIR (adjusted hazard ratio [HR] = 2.15, P = .03) and antibiotic treatment over 6 weeks (adjusted HR = 0.29, P = .0002) significantly influenced treatment failure. We observed a tentative evidence for a beneficial effect of adding rifampin to the antibiotic treatment-though not statistically significant for treatment failure (adjusted HR = 0.5, P = .07) and not for relapses (adjusted HR = 0.5, P = .10). CONCLUSIONS: We conclude that a rifampin combination is not markedly superior in Cutibacterium PJI, but a dedicated prospective multicenter study is needed.

Meningococcal disease: A paradigm of type-IV pilus dependent pathogenesis.

Neisseria meningitidis (meningococcus) is a Gram-negative bacterium responsible for two devastating forms of invasive diseases: purpura fulminans and meningitis. Interaction with both peripheral and cerebral microvascular endothelial cells is at the heart of meningococcal pathogenesis. During the last two decades, an essential role for meningococcal type IV pili in vascular colonisation and disease progression has been unravelled. This review summarises 20 years of research on meningococcal type IV pilus-dependent virulence mechanisms, up to the identification of promising anti-virulence compounds that target type IV pili.

In Vitro Activity of Ceftolozane-Tazobactam against Multidrug-Resistant Nonfermenting Gram-Negative Bacilli Isolated from Patients with Cystic Fibrosis.

Ceftolozane-tazobactam was tested against 58 multidrug-resistant nonfermenting Gram-negative bacilli (35 Pseudomonas aeruginosa, 11 Achromobacter xylosoxydans, and 12 Stenotrophomonas maltophilia isolates) isolated from cystic fibrosis patients and was compared to ceftolozane alone, ceftazidime, meropenem, and piperacillin-tazobactam. Ceftolozane-tazobactam was the most active agent against P. aeruginosa but was inactive against A. xylosoxydans and S. maltophilia In time-kill experiments, ceftolozane-tazobactam had complete bactericidal activity against 2/6 clinical isolates (33%).

Cluster-dependent colistin hetero-resistance in Enterobacter cloacae complex.

OBJECTIVES: Aims of this study were to: (i) evaluate whether the cluster membership could have an impact on hetero-resistance phenotype to colistin in the Enterobacter cloacae complex (ECC); and (ii) determine the genetic mechanism of colistin hetero-resistance in ECC. METHODS: A collection of 124 clinical isolates belonging to 13 clusters were used to analyse the hetero-resistance phenotype (MICs were determined using the broth microdilution method, Etest and population analysis profiling). Different mutants (ΔphoP, ΔphoQ, ΔphoPQ, ΔpmrA, ΔpmrB, ΔpmrAB, ΔarnE, ΔarnF and ΔarnBCADTEF) were constructed and tested for their colistin hetero-resistance phenotype. RESULTS: Based on broth microdilution and Etest results, it was shown that the hetero-resistance to colistin depended on the cluster: strains from clusters I, II, IV, VII, IX, X, XI and XII were usually hetero-resistant, whereas those from clusters III, V, VI, VIII and XIII were categorized as susceptible. However, for some cluster V and VIII strains, a small proportion (<10-7) of cells appeared resistant when tested by population analysis profiling. From a mechanistic point of view, analysis of mutants revealed that the mechanism of hetero-resistance was mainly due to the expression of the arn operon and the phoP/phoQ two-component regulatory system. CONCLUSIONS: Because the colistin hetero-resistance appeared cluster-dependent in the ECC, it should be advocated to determine the cluster of the strain associated with the infection in parallel with the MIC of colistin. The resistance mechanism may not be similar to other Enterobacteriaceae since only the two-component regulatory system PhoP/PhoQ (and not PmrA/PmrB) seemed to play a role in resistance regulation.

Pharmacokinetic variability of clindamycin and influence of rifampicin on clindamycin concentration in patients with bone and joint infections.

PURPOSE: Clindamycin, a lincosamide antibiotic with a good penetration into bone, is widely used for treating bone and joint infections by Gram-positive pathogens. To be active against Staphylococcus spp, its concentration at the infection site, C, must be higher than 2× the minimal inhibitory concentration (MIC). The aims of the work were to study the determinants of plasma clindamycin trough concentration, C min, especially the effect of co-treatment with rifampicin, and the consequences on clinical outcome. METHODS: An observational study was performed, involving patients hospitalized for a bone and joint infection who received clindamycin as part of their antibiotic treatment. Target C min was 1.7 mg/L, to reach the desired bone concentration/MIC >2, assuming a 30% diffusion into bone and MIC = 2.5 mg/L. RESULTS: Sixty one patients (mean age: 56.8 years, 57.4% male) were included between 2007 and 2011. 72.1% underwent a surgery on a foreign material, and 91.1% were infected by at least a Gram-positive micro-organism. Median C min value was 1.39 mg/L, with 58% of the values below the threshold value of 1.7 mg/L. Median C min was significantly lower for patients taking rifampicin (0.46 vs 1.52 mg/L, p = 0.034). No patient with rifampicin co-administration reached the target concentration (maximal C min: 0.85 mg/L). After a median follow-up of 17 months (1.5-38 months), 4 patients relapsed, 2 died and 47 (88.7% of the patients with known outcome) were cured, independently of association with rifampicin. CONCLUSIONS: This study shows the high inter-variability of plasma clindamycin concentration and confirms that co-treatment with rifampicin significantly decreases clindamycin trough concentrations.

Flagellin concentrations in expectorations from cystic fibrosis patients.

BACKGROUND: The aim was to measure flagellin concentrations in the expectorations of CF patients and to examine whether there are correlations with the level of respiratory insufficiency and inflammation. METHODS: Sputum samples from 31 adult patients chronically colonized with P. aeruginosa were collected and analysed for their content of flagellin and IL-8. Clinical data were extracted from patient files. RESULTS: Regardless of whether patients are colonized with mucoid strains or not, they carry clones of P. aeruginosa that express flagellin. While flagellin was present in airways of all of our CF patients, it is difficult to ascertain its contribution to inflammation (IL-8) and lung function deterioration. CONCLUSIONS: This is the first demonstration that flagellin is present in the sputum of patients. Thus, attempts to down regulate inflammation by the use of TLR5 (flagellin receptor) antagonists remain a possibility. However, this result needs to be extended to a larger number of patients to validate it for future research on this subject.

Clinical features and treatment outcomes of bone and joint nontuberculous mycobacterial infections according to immune status: a 9-year retrospective observational cohort.

OBJECTIVES: Nontuberculous mycobacteria (NTM) bone and joint infections (BJIs) are uncommon. We evaluated the characteristics of BJIs and identified differences according to immune status. METHODS: We performed a multicenter retrospective study in France involving patients with documented NTM BJI over a 9-year period. We collected the clinical and microbiological characteristics, management, and clinical outcomes of the patients. RESULTS: Overall, 95 patients were included, of whom 50.5% (48/95) were immunosuppressed. Tenosynovitis was more frequent in the immunocompetent group, and native arthritis more common in the immunosuppressed group. Mycobacerium marinum and M. abscessus complex were significantly more frequent in the immunocompetent group, and M. avium and M. xenopi were significantly more frequent in the immunosuppressed group. The combination of antibiotherapy with surgery tended to be more frequent in the immunocompetent than the immunosuppressed group (63.8% (30/47) vs 47.8% (22/46), respectively); of the latter, 45.7% (21/46) received antimicrobial therapy alone, a higher frequency than in the immunocompetent group (23.4%, 11/47). The median duration of antimicrobial treatment was similar in the two groups (11 months). Mortality was significantly higher in the immunosuppressed group. CONCLUSIONS: Although the clinical presentations and the NTM species involved in BJI differed according to immune status, most recovered completely after treatment.

Rapid emergence of resistance to linezolid and mutator phenotypes in Staphylococcus aureus isolates from an adult cystic fibrosis patient.

Linezolid has emerged as an important therapeutic option for the treatment of Staphylococcus aureus in patients with cystic fibrosis. We report the rapid emergence, upon treatment with linezolid, of linezolid-resistant S. aureus clinical isolates through the accumulation of resistance-associated 23S rRNA mutations, together with acquisition of an altered mutator phenotype.

Mycobacterium canettii Tuberculosis Lymphadenopathy in a 3-Year-old Child.

A 3-year-old male originating from Djibouti presented with a cervical mass evolving for 2 months. Tuberculous lymphadenopathy was suspected based on biopsy results, and he improved quickly on standard antituberculous quadritherapy. Subsequently some features of the mycobacterium that grew in culture were unusual. The isolate was eventually identified as Mycobacterium canettii , a peculiar species of the Mycobacterium tuberculosis complex.

Chronic meningococcemia cutaneous lesions involve meningococcal perivascular invasion through the remodeling of endothelial barriers.

Chronic meningococcemia is a form of sepsis with frequent polymorphous skin lesions. Both in vivo and in vitro data suggest that, in these lesions, meningococci gain access from the capillary lumen to the peripheral extravascular compartment, in the absence of vascular dislocation, through a paraendothelial route.

Antimicrobial Resistance in Enterobacterales Recovered from Urinary Tract Infections in France.

In the context of increasing antimicrobial resistance in Enterobacterales, the management of these UTIs has become challenging. We retrospectively assess the prevalence of antimicrobial resistance in Enterobacterales isolates recovered from urinary tract samples in France, between 1 September 2017, to 31 August 2018. Twenty-six French clinical laboratories provided the susceptibility of 134,162 Enterobacterales isolates to 17 antimicrobials. The most frequent species were E. coli (72.0%), Klebsiella pneumoniae (9.7%), Proteus mirabilis (5.8%), and Enterobacter cloacae complex (2.9%). The overall rate of ESBL-producing Enterobacterales was 6.7%, and ranged from 1.0% in P. mirabilis to 19.5% in K. pneumoniae, and from 3.1% in outpatients to 13.6% in long-term care facilities. Overall, 4.1%, 9.3% and 10.5% of the isolates were resistant to cefoxitin, temocillin and pivmecillinam. Cotrimoxazole was the less active compound with 23.4% resistance. Conversely, 4.4%, 12.9%, and 14.3% of the strains were resistant to fosfomycin, nitrofurantoin, and ciprofloxacin. However, less than 1% of E. coli was resistant to fosfomycin and nitrofurantoin. We identified several trends in antibiotics resistances among Enterobacterales isolates recovered from the urinary tract samples in France. Carbapenem-sparing drugs, such as temocillin, mecillinam, fosfomycin, cefoxitin, and nitrofurantoin, remained highly active, including towards ESBL-E.

Clinical Features and Outcome of Multidrug-Resistant Osteoarticular Tuberculosis: A 12-Year Case Series from France.

The optimal treatment for osteoarticular infection due to multidrug-resistant tuberculosis strains (MDR-OATB) remains unclear. This study aims to evaluate the diagnosis, management and outcome of MDR-OATB in France. We present a case series of MDR-OATB patients reviewed at the French National Reference Center for Mycobacteria between 2007 and 2018. Medical history and clinical, microbiological, treatment and outcome data were collected. Twenty-three MDR-OATB cases were reported, representing 3% of all concurrent MDR-TB cases in France. Overall, 17 were male, and the median age was 32 years. Six patients were previously treated for TB, including four with first-line drugs. The most frequently affected site was the spine (n = 16). Bone and joint surgery were required in 12 patients. Twenty-one patients (91%) successfully completed the treatment with a regimen containing a mean of four drugs (range, 2-6) for a mean duration of 20 months (range, 13-27). Overall, high rates of treatment success were achieved following WHO MDR-TB treatment guidelines and individualized patient management recommendations by the French National TB Consilium. However, the optimal combination of drugs, duration of treatment and role of surgery in the management of MDR-OATB remains to be determined.

Mediastinal tuberculosis in an adult patient with cystic fibrosis.

Tuberculosis (TB) is rarely observed in cystic fibrosis (CF) patients. We report the first case of mediastinal TB, associated with leg pain and skin rash, in an adult patient with CF, and discuss factors suggestive of TB in the course of CF.

Extracellular bacterial pathogen induces host cell surface reorganization to resist shear stress.

Bacterial infections targeting the bloodstream lead to a wide array of devastating diseases such as septic shock and meningitis. To study this crucial type of infection, its specific environment needs to be taken into account, in particular the mechanical forces generated by the blood flow. In a previous study using Neisseria meningitidis as a model, we observed that bacterial microcolonies forming on the endothelial cell surface in the vessel lumen are remarkably resistant to mechanical stress. The present study aims to identify the molecular basis of this resistance. N. meningitidis forms aggregates independently of host cells, yet we demonstrate here that cohesive forces involved in these bacterial aggregates are not sufficient to explain the stability of colonies on cell surfaces. Results imply that host cell attributes enhance microcolony cohesion. Microcolonies on the cell surface induce a cellular response consisting of numerous cellular protrusions similar to filopodia that come in close contact with all the bacteria in the microcolony. Consistent with a role of this cellular response, host cell lipid microdomain disruption simultaneously inhibited this response and rendered microcolonies sensitive to blood flow-generated drag forces. We then identified, by a genetic approach, the type IV pili component PilV as a triggering factor of plasma membrane reorganization, and consistently found that microcolonies formed by a pilV mutant are highly sensitive to shear stress. Our study shows that bacteria manipulate host cell functions to reorganize the host cell surface to form filopodia-like structures that enhance the cohesion of the microcolonies and therefore blood vessel colonization under the harsh conditions of the bloodstream.

Design of an integrated piggery system with recycled water, biomass production and water purification by vermiculture, macrophyte ponds and constructed wetlands.

Since 2001 the swine experimental station of Guernévez has studied biological treatment plants for nutrient recovery and water recycling, suited to the fresh liquid manure coming out of flushing systems. An integrated system with continuous recycling was set up in 2007, associated with a piggery of 30 pregnant sows. It includes a screen, a vermifilter, and macrophyte ponds alternating with constructed wetlands. The screen and the vermifilter had a lower removal efficiency than in previous studies on finishing pigs. A settling tank was then added between the vermifilter and the first lagoon to collect the worm casts. A second vermifilter was added to recover this particulate organic matter. A storage lagoon was added to compensate for evaporative losses and complete pollution abatement, with goldfish as a bioindicator of water quality. The removal efficiency of the whole system was over 90% for COD and nitrogen, over 70% for phosphorus and potassium, and more than 4 logarithmic units for pathogens (E. coli, enterococci, C perfringens). Plant production was about 20 T DM ha(-1) y(-1). Floating macrophytes (Azolla caroliniana, Eichhornia crassipes, Hydrocotyle vulgaris) were more concentrated in nutrients than helophytes (Phragmites australis, Glyceria aquatica,…). Azolla caroliniana was successfully added to feed finishing pigs.