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BackgroundMyeloid cells are key players in the recognition and response of the host against invading viruses. Paradoxically, upon HIV-1 infection, myeloid cells might also promote viral pathogenesis through trans-infection, a mechanism that promotes HIV-1 transmission to target cells via viral capture and storage. The receptor Siglec-1 (CD169) potently enhances HIV-1 trans-infection and is regulated by immune activating signals present throughout the course of HIV-1 infection, such as interferon α (IFNα).ResultsHere we show that IFNα-activated dendritic cells, monocytes and macrophages have an enhanced ability to capture and trans-infect HIV-1 via Siglec-1 recognition of viral membrane gangliosides. Monocytes from untreated HIV-1-infected individuals trans-infect HIV-1 via Siglec-1, but this capacity diminishes after effective antiretroviral treatment. Furthermore, Siglec-1 is expressed on myeloid cells residing in lymphoid tissues, where it can mediate viral trans-infection.ConclusionsSiglec-1 on myeloid cells could fuel novel CD4+ T-cell infections and contribute to HIV-1 dissemination in vivo.Electronic supplementary materialThe online version of this article (doi:10.1186/s12977-015-0160-x) contains supplementary material, which is available to authorized users.

BackgroundPulmonary abnormalities are often present in patients infected with the human immunodeficiency virus (HIV). ObjectivesThe aim of the study was to determine the prevalence and characteristics of, and risk factors for, pulmonary abnormalities in HIV-positive patients. MethodsA total of 275 HIV-positive patients [mean (± standard deviation) age 48.5 ± 6.6 years] were included in the study, of whom 95.6% had been receiving highly active antiretroviral therapy (HAART) for a mean (± standard deviation) duration of 11.9 ± 5.4 years. The median (interquartile range) CD4 lymphocyte count was 541 (392-813) cells/μL, and 92% of the patients had an undetectable viral load. We determined: (1) spirometry, static lung volumes, lung diffusing capacity, pulmonary gas exchange and exercise tolerance, and (2) the amount of emphysema via a computed tomography (CT) scan. ResultsChronic cough and expectoration (47%) and breathlessness during exercise (33.9%) were commonly reported. Airflow limitation (AL) was present in 17.2%, low pulmonary diffusing capacity in 52.2% and emphysema in 10.5−37.7% of patients, depending on the method used for quantification. Most of these abnormalities had not been diagnosed or treated previously. Smoking exposure and previous tuberculosis were the main risk factors for AL, whereas smoking exposure and several variables related to HIV infection appeared to contribute to the risk of emphysema and low diffusing capacity. ConclusionsDespite HAART, pulmonary structural and functional abnormalities are frequent in HIV-positive patients. They are probably attributable to both environmental (smoking and tuberculosis) and HIV-related factors. Most of these abnormalities remain unnoticed and untreated. Given the relatively young age of these patients, these results anticipate a significant health problem in the next few years as, thanks to the efficacy of HAART, patients survive longer and experience the effects of aging.Keywords: airflow limitation, chronic obstructive pulmonary disease, emphysema, HIV, tuberculosis, smoking IntroductionAIDS remains a challenge for health care systems around the world as a consequence of its health and also its social impact [1,2]. During the early years of the pandemic, Pneumocystis jirovecii (formerly Pneumocystis carinii) pneumonia, tuberculosis, bacterial pneumonia and Kaposi's sarcoma were the major causes of morbidity and mortality [3]. The introduction of highly active antiretroviral therapy (HAART) considerably improved the prognosis and quality of life of HIV-infected patients [4,5]. Previous studies have identified a high prevalence of airflow limitation (AL) and pulmonary emphysema in patients infected with HIV [6][7][8][9][10][11][12][13][14][15]. Yet, lung function assessment has not been included in large multicentre studies aimed at characterizing events not directly related to HIV infection in these patients [16,17]. Lung function testing is also not normally considered part of the routine clinical assessment of these patients, despite the availabili...

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The increasing prevalence of advanced chronic respiratory disease, with frequent exposure to broad-spectrum antibiotics for repeated and prolonged hospitalizations, favours the emergence of nosocomial respiratory infection by Gram-positive bacteria, such as outbreaks of Corynebacterium striatum. There is little evidence about patterns of respiratory infection, transmission and adaptive ability of this pathogen. Seventy-two C. striatum isolates from 51 advanced respiratory patients, mainly chronic obstructive pulmonary disease, were studied during 38 months. Patients were 74.8 ± 8.6 years old and 81.9% were men, who had required an average of 2.2 hospitalizations and 63.5 days in the hospital in the previous year. Of 49 isolates from 42 patients we were able to identify 12 clones by multilocus sequence analysis (MLSA), nine phenotypic variants and 22 antibiotic susceptibility patterns, and we determined their clinical and epidemiological determinants. MLSA allows identification of the existence of nosocomial outbreaks by transmission of the same or different clones, the persistence of the same clone in the environment or in patient airways for months. The study showed the high variability and adaptive capacity of the isolates, the antibiotic multidrug-resistance in all of them, and their contribution to a high morbidity and mortality (41%) during the study period.

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BackgroundThe genus Corynebacterium is composed of Gram-positive bacteria that are widely distributed throughout the environment; these bacteria are also part of the normal microbiota of human skin and mucous membranes. Multiple studies have shown that species of this genus, including C. striatum, become pathogenic to humans under special conditions. Our aim was to determine the characteristics of clinical multiresistant strains of C. striatum that were isolated in our geographical region, to determine their diversity, and to compare them with the type strain and with related species. We studied fifty-two strains of C. striatum isolated from different hospitals from Mallorca, Spain, mainly from the Hospital Joan March in Bunyola, Mallorca. Most of the strains were isolated from sputum cultures of respiratory samples from patients with chronic obstructive pulmonary disease. To gain further insight into the genetic diversity of the strains, we analysed several housekeeping genes and other genes associated with antibiotic resistance. Strains were also characterised phenotypically by their antibiotic resistance profiles and by MALDI-TOF mass spectrometry analysis.ResultsThe ITS1 region, gyrA and rpoB were chosen as the appropriate genes in the C. striatum genome to study the genetic diversity of C. striatum species and to discriminate between strains. After analysing these three genes, four sequence types (ST2, ST4, ST1 and ST11) were found to be the most abundant. Splits tree analysis of the strains demonstrated that these clinical isolates did not share any alleles with the type strain of the species. Recombination was detected within all of the C. striatum isolates, and different clonal populations were detected within the samples.ConclusionsOur results demonstrate that the isolates were best identified using gene-based molecular methods; using these methods, the isolated strains were determined to be different from the type strain of C. striatum. The ITS1 region and the gyrA and rpoB genes were selected because of their variability and were the most useful tools for discriminating between strains. The phenotype and antibiotype characteristics of the strains did not seem suitable for typing purposes. MALDI-TOF mass spectrometry can be a useful method for identifying and discriminating between C. striatum strains.