Lung Infections In Patients Research Articles

A multicenter clinical analysis of short-term efficacy of laparoscopic radical resection of hilar cholangiocarcinoma

Objective: To investigate the feasibility and safety of laparoscopic radical resection of hilar cholangiocarcinoma at multiple centers in China. Methods: Between December 2015 and August 2019, the clinical data of 143 patients who underwent LRHC in Affiliated Hospital of North Sichuan Medical College, Second Hospital of Hebei Medical University, Affiliated Hospital of Xuzhou Medical University, Affiliated Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Hunan Provincial People's Hospital, the First Hospital Affiliated to Army Medical University, Sir Run Run Shaw Hospital Affiliated to Medical College of Zhejiang University, West China Hospital of Sichuan University, Nanfang Hospital of Southern Medical University and the First Affiliated Hospital of Chongqing Medical University were collected prospectively. There were 92 males and 51 females with age of (64±11) years (range: 53 to 72 years). Bismuth type: type I, 38 cases (26.6%), type Ⅱ, 19 cases (13.3%), type Ⅲa, 15 cases (10.5%), type Ⅲb, 28 cases (19.6%) and type Ⅳ, 43 cases (30.0%). The patients within the first 10 operation cases in each operation time (the first 10 patients in each operation team) were divided into group A (77 cases), and the patients after 10 cases in each operation time were classified as group B (66 cases); the cases with more than 10 cases in the center were further divided into group A(1) (116 cases), and the center with less than 10 cases was set as group A(2) (27 cases). T test or Wilcoxon test was used to compare the measurement data between groups, and the chi square test or Fisher exact probability method was used to compare the counting data between groups. Kaplan Meier curve was used for survival analysis. Results: All patients successfully completed laparoscopic procedure. The mean operation time was (421.3±153.4) minutes (range: 159 to 770 minutes), and the intraoperative blood loss was 100 to 1 500 ml (median was 300 ml) .Recent post-operative complications contained bile leakage, abdominal bleeding, abdominal infection, gastrointestinal bleeding, and delay gastric emptying, pulmonary infection, liver failure, et al.The post-operative hospital stay was (15.9±9.2) days. The operation time in group B was relatively reduced ( (429.5±190.7)minutes vs. (492.3±173.1)minutes, t=2.063, P=0.041) and the blood loss (465 ml vs. 200 ml) was also reduced (Z=2.021, P=0.043) than that in group B. The incidence of postoperative biliary fistula and lung infection in patients in group A was significantly higher than that in group B (χ(2)=4.341, 0.007; P=0.037, 0.047) .Compared with group A(2), the operation time in group A(1) was relatively reduced( (416.3±176.5)minutes vs. (498.1±190.4)minutes, t=2.136, P=0.034) , the incidence of bile leakage and abdominal cavity infection in group A(1) was lower than that in group A(2) (χ(2)=7.537, 3.162; P=0.006, 0.046) . Kaplan Meier survival curve showed that the difference of short-term survival time between group A and group B was statistically significant (P<0.05) . Conclusions: The completion of laparoscopic hilar cholangiocarcinoma radical surgery is based on improved surgical skills, and proficiency in standardized operation procedures.It is feasible for laparoscopic radical resection of hilar cholangiocarcinoma to well experienced surgeon with cases be strictly screened, but it is not recommended for widespread promotion at this exploratory stage.

Pseudomonas Aeruginosa Induced Cell Death in Acute Lung Injury and Acute Respiratory Distress Syndrome.

Pseudomonas aeruginosa is an important opportunistic pathogen responsible for the cause of acute lung injury and acute respiratory distress syndrome. P. aeruginosa isthe leading species isolated from patients with nosocomial infection and is detected in almost all the patients with long term ventilation in critical care units. P. aeruginosa infection is also the leading cause of deleterious chronic lung infections in patients suffering from cystic fibrosis as well as the major reason for morbidity in people with chronic obstructive pulmonary disease. P. aeruginosa infections are linked to diseases with high mortality rates and are challenging for treatment, for which no effective remedies have been developed. Massive lung epithelial cell death is a hallmark of severe acute lung injury and acute respiratory distress syndrome caused by P. aeruginosa infection. Lung epithelial cell death poses serious challenges to air barrier and structural integrity that may lead to edema, cytokine secretion, inflammatory infiltration, and hypoxia. Here we review different types of cell death caused by P. aeruginosa serving as a starting point for the diseases it is responsible for causing. We also review the different mechanisms of cell death and potential therapeutics in countering the serious challenges presented by this deadly bacterium.

Computed tomography of lung infections in patients with lymphoproliferative diseases after chemotherapy

Objective : to determine CT features of pneumonia depending on the etiological agent in patients with LHP after chemotherapy. Materials and methods. 52 patients with LPD, who developed pneumonia, underwent chest CT. In all patients, the causative agent of lower respiratory tract infection was verified by microbiological diagnostic methods. Results . In the first 48 hours from the onset of the viral pneumonia, thickening of the interlobular septa and of peribronchial interstitium, part-solid and solid nodules, and hydropericardium (p < 0.01) were detected. After 48 hours, ground glass opacity, Intralobular septal thickening, “crazy-paving” pattern and hydropericardium were more often detected (p < 0.001). In the first 48 hours from the onset of invasive pulmonary mycosis, a halo sign (p < 0.01) and the prevalence of changes in the upper parts of the lungs (p < 0.05) were detected. After 48 hours, halo sign (p <0.01), a random distribution of nodules and solid nodules (p < 0.05) were detected. Conclusion . Viral or fungal etiology of lower respiratory tract infection can be excluded according to CT data with sufficient certainty, and that is undoubtedly a fundamental reason for changing further treatment tactics in such patients.

Non‐Tuberculous Mycobacteria Infections Increase NOS2 While Decreasing NO Levels

Non‐tuberculous mycobacteria (NTM) are rod‐shaped bacilli that cause lung infections in patients with weakened immune system or underlying lung disease such as cystic fibrosis, COPD, or prior tuberculosis. While it is well‐established that NTM cause lung disease, the host response to infection with NTM has not been well‐characterized. The production of reactive oxygen species (ROS) and reactive nitrogen species (RNS) by innate immune cells is considered a major defense mechanism against mycobacteria. Nitric oxide (NO), a product of inducible nitric oxide synthase (NOS2) in macrophages, plays an essential role in M. tuberculosis (MTb) infection through its bactericidal and anti‐inflammatory characteristics. Therefore, we hypothesized that NTM infection may upregulate NOS2 expression, which in turn may contribute to the host response to NTM infection. RAW 264.7 and MH‐S cells, virus transformed murine macrophages and alveolar macrophages, respectively, were exposed to NTM (M. avium‐intracellulare, or MAI) at a MOI of 25 and NO levels in cell media were monitored 4, 8, 12, 24, and 48 hours after NTM infection using a colorimetric GSNO assay. mRNA expression of NOS isoforms (NOS1, NOS2, and NOS3) in MH‐S and RAW cells were analyzed 24‐ and 48‐hours post‐infection. MH‐S cells were also transfected with siRNA to NOS2 and infected with MAI for 0.5, 4, and 24 hours, and their intracellular NTM were quantified to assess macrophage function. NO levels decreased following 4 hours of NTM exposure and remained decreased for 48 hours (P&lt;0.05). NTM infection increased the expression of NOS2 without affecting levels of other NOS isoforms (P&lt;0.05). siNOS2 transfected cells infected with MAI for more than four hours had significantly greater levels of intracellular MAI compared to scrambled negative control (P&lt;0.05). Our preliminary data are the first to demonstrate that NTM increase NOS2 expression while decreasing NO levels. Furthermore, decreasing NOS2 expression exacerbates NTM infections. Future studies will examine mechanisms whereby NTM decrease NO levels. Therefore, we propose that approaches that restore NO can enhance macrophage host defense against NTMs and improve infection clearance.Support or Funding InformationThis work was supported in part by NIH Grant R01HL102167 (RLS), Merit Review funding from the Department of Veteran’s Affairs, Office of Research and Development (RTS). NTM isolates are Isolates were provided by Emory University Hospital

Evaluation of nasal mucociliary clearance time in children with celiac disease

ObjectivesCeliac disease is an autoimmune disorder that develops because of sensitivity to gluten-containing grains in genetically disposed individuals. Nasal mucociliary clearance is the most important protective factor that protects the upper and lower airways from foreign particulates. This study aimed to investigate the effect of celiac disease on nasal mucociliary clearance. MethodsThe study included patients with celiac disease and healthy children. Nasal mucociliary clearance time was measured using the saccharin test. The children's saccharin taste time was recorded in seconds. ResultsOverall, 65 children were included: 43 patients with celiac disease (66.2%) and 22 healthy children (33.8%). Of all the children, 42 (64.6%) were female, and the average age was 11.8 ± 4 years. Nasal mucociliary clearance time of patients with celiac disease (531 ± 155 s) was significantly prolonged in comparison to that of healthy children (448 ± 80 s) (p = 0.006). No relationships were found between the diagnosis age, celiac type, and histopathological phase and compliance with the gluten-free diet and nasal mucociliary clearance time of patients with celiac disease. ConclusionsThis study showed that nasal mucociliary clearance was prolonged in patients with celiac disease. A defect in nasal mucociliary clearance increases the risk of infection and inflammation in small airways. Studies reported a high prevalence of respiratory tract infection in patients with celiac disease, which was associated with malnutrition, vitamin deficiency, and hyposplenism. The findings of the present study indicated that impairment of nasal mucociliary clearance could play a role in the development of frequent lung infections in patients with celiac disease.

Meta-analysis of risk factors for lung infection in patients with craniocerebral injury after tracheotomy

Objective To analyze the risk factors for lung infection in patients with craniocerebral injury after tracheotomy through Meta-analysis and provide a scientific reference for its prevention. Methods The inclusion and exclusion criteria were determined and the search strategies were designed. Two researchers independently searched both English and Chinese databases such as Cochrane Library, EMBASE, PubMed, CNKI, Wanfang and VIP (taking brain injury, craniocerebral injury, traumatic brain injury, tracheotomy, lung infection, pulmonary infection, risk factor, influencing factor and promotive factor as the key words) for literatures published since the databases were built to April 28th, 2019. RevMan 5.3 was used to analyze the data after the quality of literatures were assessed. Results Totally 9 articles were included, including 2 112 patients with craniocerebral injury. Meta-analysis showed that diabetes [OR=3.36, 95%CI(2.49, 4.54), P 7 d) [OR=2.32, 95%CI (1.42, 3.79); P< 0.01]were the influencing factors for lung infection in patients with craniocerebral injury after tracheotomy. Conclusions Existing evidence shows that combined with diabetes, use of hormones, high GCS score, hypoalbuminemia, occurrence of aspiration, use of non-irrigable tracheal cannula, smoking, tracheotomy time> 7 d were independent risk factors for lung infection in patients with craniocerebral injury. Key words: Craniocerebral injury; Meta-analysis; Tracheotomy; Risk factor; Lung infection

Characterization of Phenotypic and Genotypic Traits of Klebsiella pneumoniae from Lung Cancer Patients with Respiratory Infection.

BackgroundKlebsiella pneumoniae has been a leading healthcare-acquired infection (HAI) agent worldwide for decades. However, the epidemiological characteristics of K. pneumoniae in lung cancer patients with respiratory infection are unclear. Here, we characterized the frequency of K. pneumoniae in lung cancer patients with respiratory infection in a cancer hospital in China and determined the antibiotic resistance profile, virulence phenotype and clonal relationships among these K. pneumoniae strains.MethodsThe clinical data of lung cancer patients with respiratory infection from September 2017 to October 2018 were retrospectively evaluated. Microbiological methods, antimicrobial susceptibility tests, pulsed-field gel electrophoresis (PFGE), polymerase chain reaction (PCR) assays, Sanger sequencing and Galleria mellonella larvae infection model were used in this study.ResultsDuring the study period, a total of 47 lung cancer patients with respiratory infection caused by bacteria were identified, among 27 patients were identified as positive for K. pneumoniae and the positive rate was 57.45%. Among 37 nonduplicate K. pneumoniae strains from these 27 patients, 19 isolates (51.4%) were classified as multidrug resistant (MDR) with high-level resistance to, at least one agent in three or more antibiotic categories, including polymyxin B and tigecycline. Sixteen of the 37 strains (43.2%) were hypermucoviscous isolates. Extended spectrum β-lactamases-producing K. pneumoniae strains consisted of two dominant PFGE types. Furthermore, the assessment of virulence potential using a G. mellonella larvae infection model showed that K. pneumoniae isolated from these patients exhibited a high virulence level.ConclusionOur data showed that K. pneumoniae is the most critical cause of lung infection in patients with lung cancer in this hospital. The various drug resistance and virulence backgrounds of K. pneumoniae may make this clinical center a breeding ground for superbugs. It is paramount to enhance surveillance of K. pneumoniae strains and take control measures.

Gram-negative hospital pathogens at risk of severe bacterial infection

Background. Nosocomial infections remain an urgent problem of modern medicine. Along with bacterial infection of the bloodstream a special danger is posed by ventilation-dependent lung infection (VDLI), the main source which are still at the intensive care unit (ICU).Objectives. Assessment of the spread of bacterial infections in ICU over a five-year period. Analysis of the severity of postoperative complications depending on the infection location.Methods. A retrospective analysis of the frequency and form of blood flow and ventilation-dependent lung infection in patients, operated under cardiopulmonary bypass in the years 2013–2017.Results. The rate of blood contamination in the departments ranged from 8.0 to 9.8 %; against the ICU — from 17 to 24 % (p &lt; 0,01). Gram-negative associated mortality was significantly higher than gram-positive (p &lt; 0.001). Acinetobacter spp. and Klebsiella spp. are the most common agents. Analysis of the primary detection of the pathogen showed that in 73.6 % of cases, the trachea is the area of the initial localization of combined-form infection.Conclusions. The risk of bacterial complications in the early postoperative period is associated with gram-negative pathogen s (Acinetobacter spp. and Klebsiella spp.). Constant bacteriological monitoring in ICU is an effective prognostic tool of blood flow and ventilation-dependent lung infection.

Study on lung infections of patients with cancer under chemotherapy

The aim of this study is to assess the prevalence of lung infections among a group of hospitalized cancer patients who received chemotherapy as well as to describe a population of these patients. The clinical data and demographic information were collected from the archived files of in-patients referred to hematology center / Baghdad Teaching Hospital / Medical City , ministry of health, Iraq during the period of 2018.&#x0D; This study was carried out on 250 patients with different types of cancer ,they were mostly of age group (40 - 49) 59 / 250 (23.6)% , (14-19) 49 /250 (19.6%) and (60-69) 41/ 250(16.4%) . The patients had two major types of hematological malignancies: leukemia 109/250(43.6%) and lymphoma 105/250(42%), only 36/250 (14.4%) of the patients had other types of cancer which were distributed as : 26/250( 10.4 %) microangiopathic and 10 /250 (4 %) Multiple myelomoa. Statistically , there was significant correlation between age parameter and types of cancer in p&lt;0.05 (p value : 0.000).&#x0D; Patients with positive Lung infections , as recorded on their medical reports, were not in high frequency and found only in 48/250(19.2%) of the cases which were mostly shown in patients with leukemia 28/48( 58.3 %) .In spite of that there was no significant correlation between lung infections and type of cancer .&#x0D; The higher percentage of patients, who admitted to the women wards of Baghdad hospital, came from Baghdad city 132/250(52.8%) and diyala governorate 45/250(18%). The married women were 173 /250(69.2%) and mostly they were housewives 200/250(80%). The illiteracy was in 67/250(26.8% ) of patients.&#x0D; Low frequent lung infections as resulted during this study could be because of the good control of infections by giving suitable antibiotic drugs for the bacterial infections but most of patients with positive cases may be infected with viruses or fungi ,which are difficult to diagnose and treat . These infections occurred due to the immune defects induced by chemotherapy treatments . So the greatest hope for the future is the availability of more targeted anticancer drugs that have fewer side-effects on the immune system.

Burkholderia multivorans Exhibits Antibiotic Collateral Sensitivity.

Burkholderia multivorans is a member of the Burkholderia cepacia complex whose members are inherently resistant to many antibiotics and can cause chronic lung infections in patients with cystic fibrosis. A possible treatment for chronic infections arises from the existence of collateral sensitivity (CS)-acquired resistance to a treatment antibiotic results in a decreased resistance to a nontreatment antibiotic. Determining CS patterns for bacteria involved in chronic infections may lead to sustainable treatment regimens that reduce development of multidrug-resistant bacterial strains. CS has been found to occur in Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. Here, we report that B. multivorans exhibits antibiotic CS, as well as cross-resistance (CR), describe CS and CR networks for six antibiotics (ceftazidime, chloramphenicol, levofloxacin, meropenem, minocycline, and trimethoprim-sulfamethoxazole), and identify candidate genes involved in CS. Characterization of CS and CR patterns allows antibiotics to be separated into two clusters based on the treatment drug to which the evolved strain developed primary resistance, suggesting an antibiotic therapy strategy of switching between members of these two clusters.

Efficacy of Aerosolized Rifaximin versus Tobramycin for Treatment of Pseudomonas aeruginosa Pneumonia in Mice.

Pseudomonas aeruginosa is a Gram-negative opportunistic bacterial pathogen that can cause chronic lung infections in patients with cystic fibrosis (CF). The current preferred treatment for CF lung infections includes inhaled tobramycin (TOB); however, studies suggest TOB cannot effectively inhibit biofilm formation. Using an NIH small compounds drug library approved for safe use in humans, we identified rifaximin (RFX), a semisynthetic, rifamycin family, nonsystemic antibiotic that inhibits alginate production and growth in P. aeruginosa Inhibition of alginate production was further analyzed using the uronic acid carbazole assay and a promoter reporter assay that measures the transcription of the alginate biosynthetic operon. Compared to TOB, RFX significantly reduced alginate production in laboratory and CF sputum isolates of P. aeruginosa In addition, RFX showed a narrow range of MICs when measured with multidrug-resistant bacterial species of clinical relevance, synergistic activities with TOB or amikacin against clinical isolates, as well as reduction toward in vitro preformed biofilms. In C57BL/6 mice, penetration of nebulized TOB into the lungs was shown at a higher level than that of RFX. Further, in vivo assessment using a DBA/2 mouse lung infection model found increased survival rates with a single-dose treatment of nebulized RFX and decreased P. aeruginosa PAO1 bioburden with a multiple-dose treatment of RFX plus TOB. In addition, mice treated with a single exposure to dimethyl sulfoxide (DMSO), a solvent that dissolves RFX, showed no apparent toxicity. In summary, RFX may be used to supplement TOB inhalation therapy to increase efficacy against P. aeruginosa biofilm infections.

Mycobacterium bolletii Lung Disease in Cystic Fibrosis

The cystic fibrosis (CF) pathogen, Mycobacterium abscessus complex, covers three subspecies: M.abscessus, M.massiliense, and M.bolletii. There are no clinical outcome data concerning M.bolletii. Our aim was to characterize M.bolletii lung infections in patients with CF. We included patients with M.bolletii lung infection recorded between 1994 and 2012 in France. Data were collected from the CF registry, medical records, and questionnaires submitted to the CF primary physician. Strains were typed by multilocus sequence typing analysis. Fifteen cases were identified in nine CF centers. Nine patients (60%) presented with nontuberculous mycobacterial pulmonary disease. Follow-up of 13 patients showed a trend to more rapid decline in FEV1 in the first year of colonization (-9.4%; SD 19.3) in comparison with noninfected control subjects (-2.3%; SD 12.1) (P= .16). Twelve patients were treated, and 11 received oral macrolides. Treatment-induced eradication occurred in five patients (41.7%). Four patients died (26.7%), including one patient with fatal nontuberculous mycobacterial pulmonary disease. Inducible macrolide resistance was demonstrated in all strains. Patients always harbored unique strains. Our study reports the largest study cohort of CF patients infected with M.bolletii. M. bolletii infection affects both children and young adults, is most often symptomatic, and may be fatal. Macrolide-based therapies have poor effectiveness. There is no evidence of patient-to-patient transmission.

Genomic and transcriptomic characterization of Pseudomonas aeruginosa small colony variants derived from a chronic infection model.

Phenotypic change is a hallmark of bacterial adaptation during chronic infection. In the case of chronic Pseudomonas aeruginosa lung infection in patients with cystic fibrosis, well-characterized phenotypic variants include mucoid and small colony variants (SCVs). It has previously been shown that SCVs can be reproducibly isolated from the murine lung following the establishment of chronic infection with mucoid P. aeruginosa strain NH57388A. Using a combination of single-molecule real-time (PacBio) and Illumina sequencing we identify a large genomic inversion in the SCV through recombination between homologous regions of two rRNA operons and an associated truncation of one of the 16S rRNA genes and suggest this may be the genetic switch for conversion to the SCV phenotype. This phenotypic conversion is associated with large-scale transcriptional changes distributed throughout the genome. This global rewiring of the cellular transcriptomic output results in changes to normally differentially regulated genes that modulate resistance to oxidative stress, central metabolism and virulence. These changes are of clinical relevance because the appearance of SCVs during chronic infection is associated with declining lung function.

The Effect of PC945 on Aspergillus Fumigatus Lung Infection in Patients With Cystic Fibrosis

The Effect of PC945 on Aspergillus Fumigatus Lung Infection in Patients With Cystic Fibrosis

Tobramycin reduces key virulence determinants in the proteome of Pseudomonas aeruginosa outer membrane vesicles

Tobramycin is commonly used to treat Pseudomonas aeruginosa lung infections in patients with Cystic Fibrosis (CF). Tobramycin treatment leads to increased lung function and fewer clinical exacerbations in CF patients, and modestly reduces the density of P. aeruginosa in the lungs. P. aeruginosa resides primarily in the mucus overlying lung epithelial cells and secretes outer membrane vesicles (OMVs) that diffuse through the mucus and fuse with airway epithelial cells, thus delivering virulence factors into the cytoplasm that modify the innate immune response. The goal of this study was to test the hypothesis that Tobramycin reduces the abundance of virulence factors in OMVs secreted by P. aeruginosa. Characterization of the proteome of OMVs isolated from control or Tobramycin-exposed P. aeruginosa strain PAO1 revealed that Tobramycin reduced several OMV-associated virulence determinants, including AprA, an alkaline protease that enhances P. aeruginosa survival in the lung, and is predicted to contribute to the inhibitory effect of P. aeruginosa on Phe508del-CFTR Cl- secretion by primary human bronchial epithelial cells. Deletion of the gene encoding AprA reduced the inhibitory effect of P. aeruginosa on Phe508del-CFTR Cl- secretion. Moreover, as predicted by our proteomic analysis, OMVs isolated from Tobramycin treated P. aeruginosa had a diminished inhibitory effect on Phe508del-CFTR Cl- secretion compared to OMVs isolated from control P. aeruginosa. Taken together, our proteomic analysis of OMVs and biological validation suggest that Tobramycin may improve lung function in CF patients infected with P. aeruginosa by reducing several key virulence factors in OMVs that reduce CFTR Cl- secretion, which is essential for bacterial clearance from the lungs.

Epidemiological significance of genome variations in Pseudomonas aeruginosa causing chronic lung infection in patients with cystic fibrosis

Objective. To present the data on the main mechanism of molecular variation in P. aeruginosa causing chronic lung infection in patients with cystic fibrosis. Materials and Methods. A total of 1800 throat swabs and sputum samples from cystic fibrosis patients were included in the study over the 10-year period. P. aeruginosa isolates were primarily identified by the biochemical method using the API 20NE test strips (bioMerieux, France). Antimicrobial susceptibility testing was performed by disc diffusion method. Genotyping was conducted by RAPD-PCR and MLST. Whole genome sequencing of three typical P. aeruginosa isolates was performed on an Ion PGM Torrent platform with Ion Sequencing Kit and 316v1 chips (Life Technologies Thermo Fisher, US) according to the manufacturer’s protocol. The RAST web application was used for initial annotation. Results. There were three main variants of the pathogen variability found: population heterogeneity, pathogen microevolution, and replacement by another genotype of the same species. The variation of the pathogen’s genome is due to the acquisition of mobile genetic elements (plasmids), mutations in the chromosomal genes responsible for antibiotic resistance, bacterial viability and survival during persistence in a host, and changes in the prophage regions of the pathogen. Conclusions. Epidemiological significance of the molecular mechanisms of pathogen variation is primarily due to the ability of strains to form epidemiologically significant clone. This requires control measures aimed to limit emergence and distribution of such clones to be developed.

Peptide dendrimers as "lead compounds" for the treatment of chronic lung infections by Pseudomonas aeruginosa in cystic fibrosis patients: in vitro and in vivo studies.

AimIn the present work, the potential of the D-enantiomeric dendrimers dG3KL and dTNS18 was evaluated in relation to tobramycin (Tob), for the development of novel antibacterials to treat Pseudomonas aeruginosa chronic lung infections in patients with cystic fibrosis.ResultsThe activity of dendrimers against planktonic P. aeruginosa cells was less than Tob against three of the four strains tested (median minimum inhibitory concentration [MIC] 8 vs 1 µg/mL, respectively), but 32-fold higher against the PaPh32 strain isolated at posttransplantation stage. Results from comparative minimum bactericidal concentration/MIC evaluation and time–kill assay suggested a bactericidal mechanism for all test agents. Subinhibitory concentrations of both dendrimers and Tob significantly affected biofilm formation by all strains in a dose-dependent manner, although the PaPh26 strain, isolated during the chronic stage of infection, was particularly susceptible to dendrimers. The activity of dendrimers against preformed P. aeruginosa biofilm was generally comparable to Tob, considering both dispersion and viability of biofilm. Particularly, exposure to the test agent at 10 × MIC caused significant biofilm death (>90%, even to eradication), though with strain-specific differences. Single administration of dendrimers or Tob at 10 × MIC was not toxic in Galleria mellonella wax-moth larvae over 96 hours. However, contrarily to Tob, dendrimers were not protective against systemic infection caused by P. aeruginosa in G. mellonella. Kinetics of P. aeruginosa growth in hemolymph showed that bacterial load increased over time in the presence of dendrimers.ConclusionOverall, our findings indicated that dG3KL and dTNS18 peptide dendrimers show in vitro activity comparable to Tob against both P. aeruginosa planktonic and biofilm cells at concentrations not toxic in vivo. Further studies are warranted to explore different dosages and to increase the bioavailability of the peptides to solve the lack of protective effect observed in G. mellonella larvae.

T. marneffei infection complications in an HIV-negative patient with pre-existing pulmonary sarcoidosis: a rare case report

BackgroundTalaromyces marneffei (T. marneffei) is a thermal dimorphic pathogenic fungus that often causes fatal opportunistic infections in human immunodeficiency virus (HIV)-infected patients. Although T. marneffei-infected cases have been increasingly reported among non-HIV-infected patients in recent years, no cases of T. marneffei infection have been reported in pulmonary sarcoidosis patients. In this case, we describe a T. marneffei infection in an HIV-negative patient diagnosed with pulmonary sarcoidosis.Case presentationA 41-year-old Chinese man who had pre-existing pulmonary sarcoidosis presented with daily hyperpyrexia and cough. Following a fungal culture from bronchoalveolar lavage (BAL), the patient was diagnosed with T. marneffei infection. A high-resolution computed tomography (HRCT) chest scan revealed bilateral lung diffuse miliary nodules, multiple patchy exudative shadows in the bilateral superior lobes and right inferior lobes, air bronchogram in the consolidation of the right superior lobe, multiple hilar and mediastinal lymphadenopathies and local pleural thickening. After 3 mos of antifungal therapy, the patient’s pulmonary symptoms rapidly disappeared, and the physical condition improved markedly. A subsequent CT re-examination demonstrated that foci were absorbed remarkably after treatment. The patient is receiving follow-up therapy and assessment for a cure.ConclusionThis case suggested that clinicians should pay more attention to non-HIV-related lung infections in patients with pulmonary sarcoidosis. Early diagnosis and treatment with antifungal therapy can improve the prognosis of T. marneffei infection.

Polymorphonuclear Leukocytes or Hydrogen Peroxide Enhance Biofilm Development of MucoidPseudomonas aeruginosa

Pseudomonas aeruginosa is an opportunistic pathogenic bacterium involved in many human infections, including pneumonia, diabetic foot ulcers, and ventilator-associated pneumonia. P. aeruginosa cells usually undergo mucoid conversion during chronic lung infection in patients with cystic fibrosis (CF) and resist destruction by polymorphonuclear leukocytes (PMNs), which release free oxygen radicals (ROS), such as H2O2. PMNs are the main leucocytes in the CF sputum of patients who are infected with P. aeruginosa, which usually forms biofilms. Here, we report that PMNs or H2O2 can promote biofilm formation by mucoid P. aeruginosa FRD1 with the use of the hanging-peg method. The mucoid strain infecting CF patients overproduces alginate. In this study, PMNs and H2O2 promoted alginate production, and biofilms treated with PMNs or H2O2 exhibited higher expression of alginate genes. Additionally, PMNs increased the activity of GDP-mannose dehydrogenase, which is the key enzyme in alginate biosynthesis. Our results demonstrate that PMNs or H2O2 can enhance mucoid P. aeruginosa biofilms.

Establishment of a Host-to-Host Transmission Model for Mycobacterium avium subsp. hominissuis Using Caenorhabditis elegans and Identification of Colonization-Associated Genes.

Mycobacterium avium subsp. hominissuis (M. avium) is a member of the non-tuberculous mycobacteria (NTM), and is a common cause of lung infection in patients with chronic NTM lung conditions. M. avium is an environmental bacterium believed to be transmitted from environmental sources. In this work we used a recently developed model in Caenorhabditis elegans to ask whether M. avium can be transmitted from host-to-host, and the bacterial genes associated with host colonization. Infection of C. elegans was carried out by placing the nematode in cultured with M. avium. Bacteria eliminated from the intestines of infected C. elegans were used to infect naïve nematodes. In parallel experiments, to identify colonization associated genes, a transposon library of M. avium was screened for the ability to bind to HEp-2 mucosal cells. Thirty clones were identified and five selected clones with impaired adherence to HEp-2 epithelial cells were used to infect C. elegans to determine the degree of colonization. It was determined that M. avium eliminated from infected C. elegans were able to colonize a naïve C. elegans with high efficiency. Thirty of the most adherence-deficient M. avium clones obtained from the HEp-2 cell screening were sequenced to identify the location of the transposon. Many of the genes associated with the bacterial cell wall synthesis were shown to be inactivated in the selected mutants. Five out of the 30 bacterial clones were then used to infect C. elegans. All five mutants had impaired ability to colonize C. elegans compared with the wild type bacteria (decrease of 1.5–2.0 logs, p < 0.05). The limitation of this work is that the model can be used for initial screening, but other more complex systems should be used to confirm the findings. C. elegans can be used as a model to test for M. avium adherence/colonization-associated virulence determinants. All the tested adherence-deficient clones that were examined had impaired ability to colonize the host C. elegans, and some can be potentially used to prevent colonization.