Effects of repeated infections with non-typeable Haemophilus influenzae on lung in vitamin D deficient and smoking mice.

BACKGROUND: In chronic obstructive pulmonary disease (COPD), exacerbations cause acute inflammatory flare-ups and increase the risk for hospitalization and mortality. Exacerbations are common in all disease stages and are often caused by bacterial infections e.g., non-typeable Heamophilus influenzae (NTHi). Accumulating evidence also associates vitamin D deficiency with the severity of COPD and exacerbation frequency. However, it is still unclear whether vitamin D deficiency when combined with cigarette smoking would worsen and prolong exacerbations caused by repeated infections with the same bacterial strain. METHODS: Vitamin D sufficient (VDS) and deficient (VDD) mice were exposed to nose-only cigarette smoke (CS) for 14 weeks and oropharyngeally instilled with NTHi at week 6, 10 and 14. Three days after the last instillation, mice were assessed for lung function, tissue remodeling, inflammation and immunity. The impact of VDD and CS on inflammatory cells and immunoglobulin (Ig) production was also assessed in non-infected animals while serum Ig production against NTHi and dsDNA was measured in COPD patients before and 1 year after supplementation with Vitamin D3. RESULTS: VDD enhanced NTHi eradication, independently of CS and complete eradication was reflected by decreased anti-NTHi Ig's within the lung. In addition, VDD led to an increase in total lung capacity (TLC), lung compliance (Cchord), MMP12/TIMP1 ratio with a rise in serum Ig titers and anti-dsDNA Ig's. Interestingly, in non-infected animals, VDD exacerbated the CS-induced anti-NTHi Ig's, anti-dsDNA Ig's and inflammatory cells within the lung. In COPD patients, serum Ig production was not affected by vitamin D status but anti-NTHi IgG increased after vitamin D3 supplementation in patients who were Vitamin D insufficient before treatment. CONCLUSION: During repeated infections, VDD facilitated NTHi eradication and resolution of local lung inflammation through production of anti-NTHi Ig, independently of CS whilst it also promoted autoantibodies. In COPD patients, vitamin D supplementation could be protective against NTHi infections in vitamin D insufficient patients. Future research is needed to decipher the determinants of dual effects of VDD on adaptive immunity. TRAIL REGISTRATION: ClinicalTrials, NCT00666367. Registered 23 April 2008, https://www.clinicaltrials.gov/ct2/show/study/NCT00666367 .

Preoperative joint aspiration culture results and causative pathogens in total hip and knee prosthesis infections: mind the gap.

OBJECTIVES: In prosthetic joint infections (PJIs), there is no consensus about the utility of the preoperative joint aspiration culture to guide antimicrobial treatment. The main objective of this retrospective study was to investigate the value of these preoperative samples to narrow immediate postoperative empirical antimicrobial treatment in patients with a knee or hip PJI. METHODS: Adult patients admitted for an exchange procedure between June 2007 and July 2016 for whom a preoperative joint aspiration within 6 months prior to the procedure was available and with an antibiotic-free interval before sampling, were eligible. Per PJI, taking both preoperative joint aspiration and intraoperative deep samples into account, causative pathogen(s) were assessed by the current Infectious Diseases Society of America (IDSA) guidelines. Per PJI, agreement of preoperative joint aspiration cultures corresponding to the causative pathogen(s) was investigated both on species and on Gram/fungi level. RESULTS: From the 85 PJIs, on species level, the total agreement was found in 58 (68%) PJIs. On Gram/fungi level, when preoperative joint aspiration cultures yielded exclusively Gram-positive microorganisms (n = 61), a 100% predictive value for Gram positive causing pathogens was attained. Insufficient predictive value was observed in PJIs with preoperative joint aspiration yielding Gram-negative microorganisms (n = 4), a fungus (n = 1) or with sterile results (n = 19). CONCLUSION: In the immediate postoperative setting, the treating team might consider a broad spectrum empirical antibiotic regime, guided by the local epidemiology and susceptibility, which can be narrowed to Gram-positive coverage if preoperative joint aspiration cultures yield exclusively Gram-positive microorganisms.

Targeting Coagulase Activity in Staphylococcus aureus Bacteraemia: A Randomized Controlled Single-Centre Trial of Staphylothrombin Inhibition.

BACKGROUND: Staphylococcus aureus (S. aureus) bacteraemia is frequent and carries a high morbidity and mortality. Coagulases secreted by S. aureus initiate blood coagulation by directly activating prothrombin. This pathogen-activated coagulation is insensitive to most antithrombotic drugs, with the exception of small molecule direct thrombin inhibitors (DTIs). DTIs inhibit the coagulase-prothrombin complex, or staphylothrombin, and improve outcome in preclinical models of S. aureus infection. OBJECTIVE: A single-centre, randomized, controlled feasibility and safety trial of staphylothrombin inhibition with DTIs in patients with S. aureus bacteraemia. PATIENTS AND METHODS: Consecutive eligible adult patients with S. aureus positive blood cultures in the University Hospitals Leuven (Belgium) were randomized 1:1 to DTI (oral dabigatran 110 mg twice daily or intravenous argatroban according to activated partial thromboplastin time [aPTT]) for 7 to 10 days, or subcutaneous enoxaparin 40 mg once daily. Primary outcomes were feasibility and safety of DTI in patients with S. aureus bacteraemia. Secondary outcomes include D-dimer evolution (day 0-4) as marker of coagulation activation; inflammatory and microbiological parameters; and clinical outcomes including metastatic infections. RESULTS: Thirty-one percent (94/303) of screened patients were enrolled. Dabigatran plasma levels inhibited staphylothrombin. Clinically relevant bleeding (5/47 vs. 5/47) and thrombotic (7/47 vs. 7/47) complications were similar in both groups. Coagulase inhibition with DTIs was associated with a trend towards faster D-dimer decrease at day 4 (-662 ± 249 ng/mL vs. -40 ± 213 ng/mL for DTI-treated patients vs. control; p = 0.06) and a numerically lower number of persistently positive blood cultures. No differences in inflammatory parameters or other clinical outcomes were observed. CONCLUSION: Targeting staphylothrombin with DTIs is feasible in a subset of S. aureus bacteraemic patients, with comparable safety to standard thromboprophylaxis. In future studies of staphylothrombin inhibition, feasibility can be further improved by rapid diagnostics and by strategies without concomitant anticoagulant effect.

Specific members of the predominant gut microbiota predict pouchitis following colectomy and IPAA in UC.

OBJECTIVE: Pouchitis is the most common complication after colectomy with ileal pouch-anal anastomosis (IPAA) for UC and the risk is the highest within the 1st year after surgery. The pathogenesis is not completely understood but clinical response to antibiotics suggests a role for gut microbiota. We hypothesised that the risk for pouchitis can be predicted based on the faecal microbial composition before colectomy. DESIGN: Faecal samples from 21 patients with UC undergoing IPAA were prospectively collected before colectomy and at predefined clinical visits at 1 month, 3 months, 6 months and 12 months after IPAA. The predominant microbiota was analysed using community profiling with denaturing gradient gel electrophoresis followed by quantitative real-time PCR validation. RESULTS: Cluster analysis before colectomy distinguished patients with pouchitis from those with normal pouch during the 1st year of follow-up. In patients developing pouchitis, an increase of Ruminococcus gnavus (p<0.001), Bacteroides vulgatus (p=0.043), Clostridium perfringens (p=0.011) and a reduction of two Lachnospiraceae genera (Blautia (p=0.04), Roseburia (p=0.008)) was observed. A score combining these five bacterial risk factors was calculated and presence of at least two risk factors showed a sensitivity and specificity of 100% and 63.6%, respectively. CONCLUSIONS: Presence of R. gnavus, B. vulgatus and C. perfringens and absence of Blautia and Roseburia in faecal samples of patients with UC before surgery is associated with a higher risk of pouchitis after IPAA. Our findings suggest new predictive and therapeutic strategies in patients undergoing colectomy with IPAA.

Psychological comorbidity increases the risk for postinfectious IBS partly by enhanced susceptibility to develop infectious gastroenteritis.

OBJECTIVE: Psychological factors increase the risk to develop postinfectious IBS (PI-IBS), but the mechanisms involved are unclear. As stress affects the immune system, we investigated the potential interaction between psychological factors, the immune response against infectious gastroenteritis (IGE) and the development of IGE and PI-IBS in a large cohort exposed to contaminated drinking water. DESIGN: 18 620 people exposed to contaminated drinking water (norovirus, Giardia lamblia, Campylobacter jejuni) were invited to participate in a prospective controlled cohort study. They were asked to complete questionnaires assessing demographic, psychological and clinical data during the outbreak and 1 year later. At both time points, in-depth immune function (peripheral blood and rectal biopsies) was studied in a subgroup of subjects. RESULTS: 1379 subjects completed the questionnaires during the outbreak, of which 271 developed IGE. Risk factors for IGE included younger age, pre-existing dyspepsia-like symptoms, anxiety and drinking contaminated tap water. Anxiety scores before the outbreak inversely correlated with interleukin-2-expressing CD4+ T cells (r=0.6, p=0.01, n=23). At follow-up, 34 of 172 (20%) IGE subjects developed IBS compared with 24/366 exposed participants (7%, p<0.0001, χ(2) test). A Th2 cytokine phenotype at time of infection was associated with increased risk for PI-IBS 1 year later. Except for increased B cell numbers, no evidence for systemic or rectal mucosal immune activation in PI-IBS was demonstrated at follow-up. CONCLUSIONS: Our study shows that the increased risk of patients with psychological comorbidity to develop PI-IBS may partly result from an increased susceptibility to develop IGE, possibly resulting from a Th2-immune bias. TRIAL REGISTRATION NUMBER: (ClinicalTrials.gov NCT01497847).

Characterisation of a collection of Streptococcus pneumoniae isolates from patients suffering from acute exacerbations of chronic bronchitis: in vitro susceptibility to antibiotics and biofilm formation in relation to antibiotic efflux and serotypes/serogroups.

The correlation between Streptococcus pneumoniae serotypes, biofilm production, antibiotic susceptibility and drug efflux in isolates from patients suffering from acute exacerbations of chronic bronchitis (AECB) remains largely unexplored. Using 101 isolates collected from AECB patients for whom partial (n=51) or full (n=50) medical details were available, we determined serotypes (ST)/serogroups (SG) (Quellung reaction), antibiotic susceptibility patterns [MIC (microdilution) using EUCAST and CLSI criteria] and ability to produce biofilm in vitro (10-day model; crystal violet staining). The majority of patients were 55-75 years old and <5% were vaccinated against S. pneumoniae. Moreover, 54% showed high severity scores (GOLD 3-4), and comorbidities were frequent including hypertension (60%), cancer (24%) and diabetes (20%). Alcohol and/or tobacco dependence was >30%. Isolates of SG6-11-15-23, known for large biofilm production and causing chronic infections, were the most prevalent (>15% each), but other isolates also produced biofilm (SG9-18-22-27 and ST8-20 being most productive), except SG7, SG29 and ST5 (<2% of isolates each). Resistance (EUCAST breakpoints) was 8-13% for amoxicillin and cefuroxime, 35-39% for macrolides, 2-8% for fluoroquinolones and 2% for telithromycin. ST19A isolates showed resistance to all antibiotics, ST14 to all except moxifloxacin, and SG9 and SG19 to all except telithromycin, moxifloxacin and ceftriaxone (SG19 only). Solithromycin and telithromycin MICs were similar. No correlation was observed between biofilm production and MIC or efflux (macrolides, fluoroquinolones). S. pneumoniae serotyping may improve AECB treatment by avoiding antibiotics with predictable low activity, but it is not predictive of biofilm production.

Clinical outcome of parapneumonic empyema in children treated according to a standardized medical treatment.

UNLABELLED: Treatment of parapneumonic empyema (PE) consists of intravenous antibiotics and, in case of large effusions and persisting fever, pleural chest drain (±intrapleural fibrinolytics) or video-assisted surgical intervention. We standardized the treatment for PE in our tertiary care center choosing a first-step nonsurgical approach. The aim was to evaluate the need for surgery and to collect data on disease course, outcome, and microbiology. For all children treated for PE between 2006 and 2013, data were prospectively collected concerning treatment, length of stay, duration of fever, complications, and causative agent. Of 132 children treated for PE, 20 % needed surgical intervention. Analyzed per year, the need for surgery decreased from almost 40 % in 2007 to 0 % in 2010 again increasing to 40 % although this did not reach statistical significance (p = 0.115). Median duration of "in-hospital fever" was 5 days (IQR, 3-8). The duration of fever correlated with pleural LDH (r = 0.324; p = 0.002) and pleural glucose (r = -0.248; p = 0.021) and was inversely correlated with pleural pH (r = -0.249; p = 0.046). Based on pleural PCR data, 85 % of PE were caused by Streptococcus pneumoniae (40 % serotype 1). CONCLUSION: After introduction of a standardized primary medical approach (chest drain ± fibrinolysis) for PE in our institution, the need for surgical rescue interventions overall remained at 20 %, which is higher than in some other reports. Difference in microbiology or disease severity could not be proven.

The role of staphylothrombin-mediated fibrin deposition in catheter-related Staphylococcus aureus infections.

Staphylococcus aureus (S. aureus) is a frequent cause of catheter-related infections. S. aureus secretes the coagulases staphylocoagulase and von Willebrand factor-binding protein, both of which form a staphylothrombin complex upon binding to prothrombin. Although fibrinogen and fibrin facilitate the adhesion of S. aureus to catheters, the contribution of staphylothrombin-mediated fibrin has not been examined. In this study, we use a S. aureus mutant lacking both coagulases (Δcoa/vwb) and dabigatran, a pharmacological inhibitor of both staphylothrombin and thrombin, to address this question. Genetic absence or chemical inhibition of pathogen-driven coagulation reduced both fibrin deposition and the retention of S. aureus on catheters in vitro. In a mouse model of jugular vein catheter infection, dabigatran reduced bacterial load on jugular vein catheters, as well as metastatic kidney infection. Importantly, inhibition of staphylothrombin improved the efficacy of vancomycin treatment both in vitro and in the mouse model.

In young children, persistent wheezing is associated with bronchial bacterial infection: a retrospective analysis.

BACKGROUND: Young children with persistent wheezing pose a diagnostic and therapeutical challenge to the pediatrician.We aimed to evaluate bacterial bronchial infection as a possible reason for non response to conventional asthma therapy, and to identify and characterise the predominant pathogens involved. METHODS: We retrospectively analysed microbiological and cytological findings in a selected population of young wheezers with symptoms unresponsive to inhaled corticosteroid (ICS) therapy, who underwent flexible bronchoscopy with bronchoalveolar lavage (BAL). Procedural measures were taken to limit contamination risk and quantitative bacterial culture of BAL fluid (significance cut-off ≥ 104 colony-forming units/ml) was used. Modern microbiological methods were used for detection of a wide panel of pathogens and for characterisation of the bacterial isolates. RESULTS: 33 children aged between 4 and 38 months, without structural anomalies of the conductive airways were evaluated. Significant bacterial BAL cultures were found in 48,5 % of patients. Haemophilus influenzae was isolated in 30,3 %, Streptococcus pneumoniae in 12,1 % and Moraxella catarrhalis in 12,1 %. All H. influenzae isolates were non-encapsulated strains and definitely distinguished from non-haemolytic H. haemolyticus. Respiratory viruses were detected in 21,9 % of cases with mixed bacterial-viral infection in 12,1 %. Cytology revealed a marked neutrophilic inflammation. CONCLUSIONS: Bacterial infection of the bronchial tree is common in persistent preschool wheezers and provides a possible explanation for non response to ICS therapy. Non-typeable H. influenzae seems to be the predominant pathogen involved, followed by S. pneumoniae and M. catarrhalis.

Screening femoral heads from living donors: a prospective study comparing swab-agar versus bone fragment-broth culture.

Femoral heads are an important source of allograft bone used in reconstructive orthopaedic surgery. The sterility of donor material is of major importance for the recipient. Femoral heads intraoperatively retrieved during hip arthroplasty from medically screened living donors are routinely checked with a surface swab to exclude microbiological contamination. There is, however, evidence that swab cultures have limited sensitivity. We therefore prospectively compared two ways of screening femoral heads. Bacterial recovery from swabs in Amies transport medium taken intraoperatively, subsequently transported to the microbiology laboratory and inoculated on agar and in broth was compared with the recovery from a bone fragment also taken intraoperatively but immediately inoculated into Wilkins Chalgren broth. Forty femoral heads were tested with both methods. Bacteria were cultured neither from the femoral surface swabs nor from the femoral fragments. Consequently no distinct conclusions regarding the sensitivity of both techniques could be drawn. In addition the bacterial yield of two swabs in Amies transport medium streaked on a variety of culture media other than the conventional agar plates was also studied. Culturing of these swabs resulted in the detection of bacteria that are predominantly considered contaminants.

Serum (1-3)-beta-D-glucan as a tool for diagnosis of Pneumocystis jirovecii pneumonia in patients with human immunodeficiency virus infection or hematological malignancy.

(1-3)-Beta-D-Glucan (BG) reactivity was tested in serum samples from 28 patients with human immunodeficiency virus infection or a hematological malignancy and Pneumocystis jirovecii pneumonia (PCP) and 28 control patients. The sensitivity and specificity of BG detection with the Fungitell assay for PCP were 100 and 96.4%, respectively, using a cutoff value of 100 pg/ml. Serum BG testing looks promising for the noninvasive diagnosis of PCP. Our data suggest that a higher cutoff value for the diagnosis of PCP than for the diagnosis of invasive aspergillosis or candidiasis could be used safely and will improve the specificity of the test.

Comparison of microbiological culture methods in screening allograft tissue. Swab versus nutrient broth.

In order to reduce the risk of transmission of infectious diseases through transplantation of tissue allografts, one should examine tissues for the presence of microorganisms. However, there are no detailed tissue banking guidelines describing the culture method or incubation time to be used. Therefore, we compared two culture methods--blood agar plate versus Wilkins Chalgren broth--and three incubation times--2, 7 or 14 days for their performance. The ultimate aim is to use the optimal setting as standard operating procedure (SOP) for tissue allograft cultures. From 70 consecutive donors, 919 tissue samples were taken. All 919 tissue samples were incubated on blood agar as well as in Wilkins Chalgren broth for 7 days. 567 of these 919 tissue samples were left to incubate up to 14 days. Wilkins Chalgren broth yielded 24.5% (139/567) positive cultures after 14 days of incubation. This was slightly more than the growth on blood agar after 14 days (22.9%--130/567) (p=n.s.) and significantly more than the growth in Wilkins Chalgren broth after 7 days of incubation (21.9%--124/567) (p<0.05). Based on these results, Wilkins Chalgren broth has been implemented as the SOP. Since the yield of positive cultures increased from 2 to 7 days of incubation in broth (1.8 times) and the variability of species cultured from 7 to 14 days of incubation shifted towards mostly microorganisms known to be common contaminants, we established the cut-off at 7 days of incubation in Wilkins Chalgren broth.

Antimicrobial susceptibility of coagulase-negative staphylococci on tissue allografts and isolates from orthopedic patients.

Allograft infection occurs at a rate not different from that of similar procedures with large allografts or sterilized prosthetic devices and is usually caused by coagulase-negative staphylococci (CNS). CNS are feared for their limited antimicrobial susceptibility. We aimed at investigating this risk. CNS were isolated from 260 of 1461 allograft tissue grafts and compared with 384 consecutive clinical isolates from a general orthopedic population (258 patients). The CNS were identified and examined for their susceptibility to nine antibiotics used in routine practice. Staphylococcus epidermidis was the most commonly identified (35%) and the most resistant species of the allograft isolates. Comparing the overall antibiotic susceptibility patterns, clinical pathogens were significantly more resistant to six of the nine antibiotics (p < 0.01), namely penicillin, oxacillin, erythromycin, clindamycin, ofloxacin, and gentamicin. In conclusion, massive allograft infection is a well-known life-threatening surgical risk. However, we did demonstrate that allograft-related in contrast to orthopedic clinics-related CNS, are susceptible to commonly used first and second line antibiotics.

Prospective clinical evaluation of lower cut-offs for galactomannan detection in adult neutropenic cancer patients and haematological stem cell transplant recipients.

The recent advent of an improved commercial serum enzyme-linked immunosorbent assay (ELISA) for the detection of circulating galactomannan (GM), a major constituent of Aspergillus cell walls, has contributed to the diagnosis of invasive aspergillosis (IA) in many haematology and transplant centres. However, the optimal threshold for positivity remains a matter of debate. We prospectively evaluated the impact of lowering the cut-off in 124 neutropenic episodes with a high pretest probability for IA. Two new cut-off points, lower than previously accepted, are proposed: (a) a 'static' cut-off at 0.8 and (b) a 'dynamic' cut-off at 0.5. A single assay with an optical density (OD) index > or = 0.8 warrants the initiation of anti-Aspergillus therapy. A further lowering of the 'static' threshold seems not clinically feasible given the drop in positive predictive value (PPV). However, the demonstration of at least two sequential sera with an OD > or = 0.5 ('dynamic' threshold) increased the specificity and the PPV to 98.6% and the efficiency to 98%. Applying both cut-offs to a subgroup of 21 'possible' fungal infections further identified and upgraded six cases of IA. However, the clinical benefit of lower cut-offs (particularly for earlier diagnosis) depends upon the kinetics of antigenaemia and the intensity of serum sampling.

Use of circulating galactomannan screening for early diagnosis of invasive aspergillosis in allogeneic stem cell transplant recipients.

Screening for galactomannan (GM) has been adopted by many European centers as part of the management plan for allogeneic stem cell transplant recipients. However, the temporal onset of GM antigenemia remains unknown. A series of allogeneic stem cell transplant recipients were monitored prospectively, and the relationship between antigenemia and other diagnostic triggers for initiation of antifungal therapy was analyzed. GM detection had a sensitivity of 94.4% and a specificity of 98.8%. Positive and negative predictive values were 94.4% and 98.8%, respectively. This statistical profile was better than that of other triggers, including unexplained fever, new pulmonary infiltrates, isolation of Aspergillus species, and abnormalities seen on computed tomography. Antigenemia preceded diagnosis on the basis of radiologic examination or Aspergillus isolation by 8 and 9 days in 80% and 88.8% of patients, respectively. Antigenemia preceded therapy in 83.3% of patients. Detection of GM was especially useful when patients were receiving steroid treatment or when coexisting conditions masked the diagnosis of invasive aspergillosis. Prospective screening for GM allows earlier diagnosis of aspergillosis than do conventional diagnostic criteria.