Treatment of bone and joint infections by ceftazidime/avibactam and ceftolozane/tazobactam: a cohort study.

OBJECTIVES: Ceftazidime/avibactam (C/A) and ceftolozane/tazobactam (C/T) are two novel antibacterials with known efficacy against Gram-negative bacteria (GNB). We aimed to describe the efficacy and safety of surgical management combined with C/A or C/T treatment for bone and joint infections (BJIs). METHODS: We conducted an observational, bicentric study of patients treated with C/A or C/T for a BJI between May 2016 and June 2019. Failure was defined as the need for unplanned additional antibiotic treatment or orthopaedic surgery, or death due to the BJI up to the patient's latest visit. RESULTS: Overall, 15 patients were included. Nine patients were treated with C/A, mainly for polymicrobial BJI due to multidrug-resistant (MDR) bacteria (Enterobacteriaceae, n = 7). Six patients were male, the median age was 66 years and the median Charlson comorbidity index (CCI) was 5. It was the first septic episode at the site in 3/9 patients. The cure rate was 7/9 (median follow-up, 272 days). Two patients showed C/A-related confusion. Five patients were treated with C/T for BJI involving MDR Pseudomonas aeruginosa. Four patients were male, the median age was 53 years and the median CCI was 2. All patients had previous septic episodes at the infection site. The cure rate was 3/5 (median follow-up, 350 days). One patient was successfully treated by C/T then C/A for multistage spondylodiscitis. CONCLUSION: In our experience, C/A and C/T are two effective and safe options, even as salvage treatment for BJI due to MDR-GNB despite the absence of label, however more data are warranted.

Bloodstream infections in older population: epidemiology, outcome, and impact of multidrug resistance.

Bloodstream infections (BSIs) among older patients are frequent with high rate of mortality. Infections with multidrug-resistant organisms (MDRO) are associated with higher mortality than with susceptible microorganisms. We aimed to evaluate the prevalence of MDRO infection during BSI in older population and the factors associated with unfavorable outcome. This study is a retrospective cohort of all BSI episodes occurring among older patients (> 65yo), from April 1, 2010, to December 31, 2016, in a French university hospital for geriatric medicine. A total of 255 BSI episodes were analyzed. Mean age was 86.3±6.5 years, and sex ratio (M/F) was 0.96. Main comorbidities were orthopedic device (26.7%), active neoplasia (24.3%), and diabetes mellitus (18.4%). Main primary sites of infection were urinary tract infections (56.9%), respiratory tract infections (10.6%), intra-abdominal infections (7.1%), and skin and soft tissue infections (4.7%). Main bacteria identified were Escherichia coli (45.1%), Staphylococcus aureus (14.1%), enterococci (10.7%), coagulase-negative staphylococci (CoNS) (5.5%), and streptococci (5.1%). MDROs were involved in 17.2% of BSI (gram-negative bacilli: 9.0%; CoNS: 4.3%; and methicillin-resistant S. aureus (MRSA): 3.9%). The main factor associated with MDRO BSI was colonization with MDRO (OR=6.29; 95%CI=2.9-14.32). Total mortality was 18.4% and significantly higher in case of initial severity (OR=3.83; 95%CI=1.75-8.38), healthcare-associated infection (OR=5.29; 95%CI=1.11-25.30), and MRSA BSI (OR=9.16; 95%CI=1.67-50.16). BSI due to MDRO is frequent in older population and is strongly associated with carriage of MDRO. Healthcare-associated BSI, severe episodes, and BSI due to MRSA are associated with unfavorable outcome. In these cases, a broad-spectrum antibiotic should be promptly initiated.

[Leptospirosis]. / Leptospirose.

Leptospirosis. Leptospirosis is the first worldwide anthropozoonosis with an incidence of 1 000 000 cases per year. It is more frequently encountered in tropical areas but also can be diagnosed in tempered places. In France, the most exposed people are athletes in fresh water (canoeing, rafting, caving...) and agricultural workers. The peak incidence occurs in late summer. After transcutaneous or mucosal penetration, Leptospira can cause direct tissue injury by invasion, or indirect injury by toxinic and/or immunological mechanism. Also called summer flu, the clinical presentation is variable: it ranges from simple flu-like illness to septic shock with multiple organ dysfunction syndrome, with varying degrees of fever, headache or myalgia. Conjunctival suffusion is also very evocative. Biology can show thrombocytopenia, lymphopenia, cholestasis, elevated liver enzymes, renal failure, hematuria and proteinuria. Mortality occurs very rarely if organ failures (renal failure, pulmonary edema lesions ...) are undertaken by adequate therapy. The diagnosis is usually based on serology (micro-agglutination test), repeated 15 days after the first test. A first negative serology is not sufficient to rule out the diagnosis. PCR detection is also available and can facilitate the diagnosis of leptospirosis. A vaccine is available but it only protects against serogroup Icterohaemorrhagiae. It is recommended for professional expositions, but there is no consensus for leisure activities.

Leptospirose. La leptospirose est la première anthropozoonose de répartition mondiale, avec une incidence estimée à 1 million de cas par an. Elle est cependant plus fréquente dans les pays tropicaux. En France métropolitaine, les personnes les plus exposées sont les sportifs en eau douce (canoë- kayak, rafting, spéléologie…) et les travailleurs agricoles. Le pic d'incidence a lieu à la fin de l'été. Après pénétration cutanée ou muqueuse, les leptospires peuvent entraîner des lésions directes par envahissement tissulaire et indirectes par mécanisme toxinique et/ou immunologique. Le tableau clinique de la leptospirose, aussi appelée « grippe d'été ¼, est protéiforme : il va du simple syndrome grippal au sepsis sévère avec défaillance multiviscérale, avec à des degrés divers de la fièvre, des céphalées, des myalgies et une suffusion conjonctivale très évocatrice. La biologie peut montrer une thrombopénie, une lymphopénie, une cholestase, une cytolyse hépatique, une insuffisance rénale, une hématurie et une protéinurie. La mortalité est en règle quasi nulle si les éventuelles défaillances d'organes (insuffisance rénale, oedème pulmonaire lésionnel…) sont suppléées par une réanimation adéquate. Habituellement, le diagnostic repose sur la sérologie (test de micro-agglutination) répétée à 15 jours d'intervalle. Une première sérologie négative ne suffit pas à écarter le diagnostic. La recherche par polymerase chain reaction (PCR) facilite aujourd'hui le diagnostic de la leptospirose. Un vaccin est disponible mais ne protège que contre le sérogroupe Icterohaemorrhagiae. Il est recommandé pour les professionnels exposés, mais il n'y a pas de consensus concernant son utilisation lors des activités de loisirs.

Optical extinction in a single layer of nanorods.

We demonstrate that almost 100% of incident photons can interact with a monolayer of scatterers in a symmetrical environment. Nearly perfect optical extinction through free-standing transparent nanorod arrays has been measured. The sharp spectral opacity window, in the form of a characteristic Fano resonance, arises from the coherent multiple scattering in the array. In addition, we show that nanorods made of absorbing material exhibit a 25-fold absorption enhancement per unit volume compared to unstructured thin film. These results open new perspectives for light management in high-Q, low volume dielectric nanostructures, with potential applications in optical systems, spectroscopy, and optomechanics.

Efficient white light emission by upconversion in Yb(3+)-, Er(3+)- and Tm(3+)-doped Y2BaZnO5.

We report efficient white upconversion luminescence in Yb(3+)-, Er(3+)- and Tm(3+)-doped monophasic and biphasic Y(2)BaZnO(5) phosphors under 977 nm near-infrared excitation and at low excitation power densities (down to ∼25 mW mm(-2)).

Impedance of a nanoantenna and a single quantum emitter.

Antennas are widely used by electrical engineers to enhance the coupling between propagating waves and electric sources or detectors. It is thus tempting to develop an optical analog to tailor visible light emission or absorption by an atom or a molecule. This idea has been put forward recently and it has been demonstrated that both the radiative rate and the emission pattern of optical emitters can be modified by metallic nanostructures. In this Letter, we introduce the concept of impedance for a nanoantenna and for two-level systems or nanoparticles described by electric dipole moments. We show how these concepts can be used to reconcile different descriptions and also to optimize nanoantennas.

Scattering forces from the curl of the spin angular momentum of a light field.

Light forces on small (Rayleigh) particles are usually described as the sum of two terms: the dipolar or gradient force and the scattering or radiation pressure force. The scattering force is traditionally considered proportional to the Poynting vector, which gives the direction and magnitude of the momentum flow. However, as we will show, there is an additional nonconservative contribution to the scattering force arising in a light field with nonuniform helicity. This force is shown to be proportional to the curl of the spin angular momentum of the light field. The relevance of the spin force is illustrated in the simple case of a 2D field geometry arising in the intersection region of two standing waves.

Quantum thermal bath for molecular dynamics simulation.

Molecular dynamics (MD) is a numerical simulation technique based on classical mechanics. It has been taken for granted that its use is limited to a large temperature regime where classical statistics is valid. To overcome this limitation, the authors introduce in a universal way a quantum thermal bath that accounts for quantum statistics while using standard MD. The efficiency of the new technique is illustrated by reproducing several experimental data at low temperatures in a regime where quantum statistical effects cannot be neglected.

Optical resonances in one-dimensional dielectric nanorod arrays: field-induced fluorescence enhancement.

Arrays of transparent dielectric nanorods are shown to produce very large local field enhancements at specific resonant conditions. These structures would lead to enhancement of molecular fluorescence signals without quenching. The resonant angular width and field enhancements are analytically derived as a function of wavelength, grating period, rod radius, and dielectric constant.

Extraordinary optical reflection from sub-wavelength cylinder arrays.

A multiple scattering analysis of the reflectance of a periodic array of sub-wavelength cylinders is presented. The optical properties and their dependence on wavelength, geometrical parameters and cylinder dielectric constant are analytically derived for both s- and p-polarized waves. In absence of Mie resonances and surface (plasmon) modes, and for positive cylinder polarizabilities, the reflectance presents sharp peaks close to the onset of new diffraction modes (Rayleigh frequencies). At the lowest resonance frequency, and in the absence of absorption, the wave is perfectly reflected even for vanishingly small cylinder radii.