P. aeruginosa in the paranasal sinuses and transplanted lungs have similar adaptive mutations as isolates from chronically infected CF lungs

BackgroundPseudomonas aeruginosa cells are present as biofilms in the paranasal sinuses and the lungs of chronically infected cystic fibrosis (CF) patients. Since different inflammatory responses and selective antibiotic pressures are acting in the sinuses compared with the lungs, we compared the adaptive profiles of mucoid and non-mucoid isolates from the two locations.MethodsWe studied the genetic basis of phenotypic diversification and gene expression profiles in sequential lung and sinus P. aeruginosa isolates from four chronically infected CF patients, including pre- and post-lung transplantation isolates.ResultsThe same phenotypes caused by similar mutations and similar gene expression profiles were found in mucoid and non-mucoid isolates from the paranasal sinuses and from the lungs before and after transplantation.ConclusionBilateral exchange of P. aeruginosa isolates between the paranasal sinuses and the lungs occurs in chronically infected patients and extensive sinus surgery before the lung transplantation might prevent infection of the new lung.     

Pharmacokinetics of colistin after nebulization or intravenous administration of colistin methanesulphonate (Colimycin®) to cystic fibrosis patients

ObjectivesColistin, administered as the prodrug colistin methanesulphonate (CMS), is an antibiotic frequently administered as aerosol in cystic fibrosis (CF) patient. Our aim was to assess the plasma PK of colistin in CF patients treated with CMS administered intravenously or as aerosol and to compare these results with those previously reported in healthy volunteers.MethodsSix CF patients were included, CMS and colistin concentrations were measured in plasma, urine and sputum. Either after single intravenous administration of 2 Million International Unit (MIU) or after repeated nebulizations of 2 MIU of CMS. PK of CMS and colistin were assessed by a mixed effect modeling approach.ResultsRenal clearance of CMS was lower in CF patients compared to that previously reported in healthy volunteers (64.3 mL/min (RSE = 15%) vs. 103 mL/min (RSE = 8%)). However, apparent clearance of colistin was higher in CF patients compared to healthy volunteers (124 mL/min (RSE = 13%) vs. 48.7 mL/min (RSE = 15%)), resulting in reduced systemic exposure to colistin (dose normalized AUC (2 MIU) of 7.4 h.mg/L/MIU vs. 11.2 h.mg/L/MIU). After repeated nebulizations, colistin concentrations were very low in plasma (<0.21 mg/L).ConclusionsAlthough our study suggests a lower median dose normalized colistin plasma concentrations in CF patients compared with healthy controls, this difference was not significant and a larger study is needed to substantiate this.     

Epidemiology and resistance of Achromobacter xylosoxidans from cystic fibrosis patients in Dijon,Burgundy: First French data

BackgroundAchromobacter xylosoxidans is an emerging pathogen in cystic fibrosis (CF) patients recognised as causal agent of inflammation. The prevalence of infection or colonisation is variable among CF centres. We report here the first epidemiological data about A. xylosoxidans in a French CF centre: Dijon, Burgundy.MethodsAll isolates recovered from the patients affiliated with our centre in 2010 since their first visit were included. Antimicrobial susceptibility was determined by disk diffusion method and E-test. Molecular epidemiology was performed by Pulsed Field Gel Electrophoresis (PFGE) and compared with repetitive sequence-based PCR (rep-PCR, DiversiLab®). We also sequenced the constitutive bla-_oxa-114 gene.ResultsOut of 120 patients, 21 (17.5%) had at least one positive culture with A. xylosoxidans since they started to receive routine care in our CF centre (447 isolates). Median age at first positive culture was 16 years (range 3–34 years). Most patients were colonised by their own strain, cross-contamination was very rare. We observed two cases of intra-family spread. DiversiLab® is a useful tool as efficient as PFGE to compare isolates recovered simultaneously from different patients when an outbreak is suspected. However, PFGE remains the reference method for long-term survey of chronically colonised patients. We detected new OXA-114 variants and the new oxacillinase OXA-243 (88% amino acid identity with OXA-114). Acquired resistance to ciprofloxacin, ceftazidime and carbapenems was frequent. In 2010, 7 patients harboured strains resistant to ceftazidime, 6 patients strains with decreased susceptibility to carbapenems (especially meropenem) and 12 patients strains resistant to ciprofloxacin.ConclusionsIn our centre, the high prevalence of colonisation is not due to cross-contamination. Our main concern is the high rate of antimicrobial resistance.     

Implementation of European standards of care for cystic fibrosis — Control and treatment of infection

BackgroundSeveral guidelines on infection control and treatment of infection exist for cystic fibrosis (CF) caregivers, although the extent of implementation is variable.MethodsAdherence to European Consensus Guidelines for CF was studied by sending surveys to named healthcare professionals in 487 European CF centres/units. Qualitative data analysis was performed.ResultsA total of 177/547 (32%) surveys were returned. Infection control policies were implemented by most (77%) respondents. Separation of patients with Burkholderia cepacia was more common in adults (95%) than children (9%), and was implemented by 53% of respondents for Pseudomonas aeruginosa. Nebulised colistin plus oral ciprofloxacin was the most common (43%) therapy for P. aeruginosa infection. First infections of P. aeruginosa were usually treated with inhaled tobramycin; 41% of repondents did not intervene until lung function deteriorated. Most exacerbations were treated for less than the recommended period.ConclusionsEuropean Consensus Guidelines are widely adhered to. Areas for improvement include: initiating therapy for exacerbations early, separating infected patients and optimising duration of antibiotic therapy.     

Early aggressive eradication therapy for intermittent Pseudomonas aeruginosa airway colonization in cystic fibrosis patients: 15 years experience

BackgroundSince 1989, CF-patients intermittently colonized with Pseudomonas aeruginosa have been treated with inhaled colistin and oral ciprofloxacin in the Copenhagen CF-centre. The study evaluates 15 years results of this treatment.MethodsAll isolates of P. aeruginosa from CF-patients intermittently colonized with P. aeruginosa from 1989 to 2003 were identified All anti-P. aeruginosa treatments were evaluated for antibiotics used, treatment duration, pseudomonas-free interval and development of chronic infection. All P. aeruginosa isolates were assessed for resistance and for non-mucoid or mucoid phenotype.Results146 CF-patients were included in the study (1106 patient-years). 99 patients had first ever isolate during the study period. Median observation time 7 years (0.1–14.9). 12 patients developed chronic infection. A Kaplan Meyer plot showed protection from chronic infection in up to 80% of patients for up to 15 years. 613 colistin/ciprofloxacin treatments were given. There was no difference in pseudomonas-free interval comparing 3 weeks (5 months) and 3 months (10.4 months) of colistin and ciprofloxacin, but a significant difference compared to no treatment (1.9 months). Patients developing chronic infection had significantly shorter pseudomonas-free interval after treatment of first ever isolate compared to patients remaining intermittently colonized (p < 0.003). Treatment failure (P. aeruginosa-positive culture immediately after ended treatment of first ever isolate) was a strong risk factor for development of chronic infection after 3–4 years, OR 5.8. 1093 pseudomonas-isolates were evaluated (86.6% non-mucoid). No colistin-resistance was found. Ciprofloxacin-resistance was found in 4% of isolates.ConclusionTreatment of intermittent P. aeruginosa colonization in CF-patients using colistin and ciprofloxacin can protect up to 80% of patients from development of chronic infection for up to 15 years. A positive culture immediately after treatment of first ever isolate is a strong risk factor for development of chronic infection. We found no colistin-resistance and minimal ciprofloxacin-resistance.     

Molecular analysis of changes in Pseudomonas aeruginosa load during treatment of a pulmonary exacerbation in cystic fibrosis

BackgroundIntravenous antibiotics for pulmonary exacerbations (PEs) of cystic fibrosis (CF) usually target Pseudomonas aeruginosa. Insights into the CF lung microbiome have questioned this approach. We used RT-qPCR to determine whether intravenous antibiotics reduced P. aeruginosa numbers and whether this correlated with improved lung function. We also investigated antibiotic effects on other common respiratory pathogens in CF.MethodsSputa were collected from patients when stable and again during a PE. Sputa were expectorated into a RNA preservation buffer for RNA extraction and preparation of cDNA. qPCR was used to enumerate viable P. aeruginosa as well as Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, Burkholderia cepacia complex and Aspergillus fumigatus.ResultsFifteen CF patients were followed through 21 PEs. A complete set of serial sputum samples was unavailable for two patients (three separate PEs). P. aeruginosa numbers did not increase immediately prior to a PE, but numbers during intravenous antibiotic treatment were reduced ≥ 4-log in 6/18 and ≥ 1-log in 4/18 PEs. In 7/18 PEs, P. aeruginosa numbers changed very little with intravenous antibiotics and one patient demonstrated a ≥ 2-log increase in P. aeruginosa load. H. influenzae and S. pneumoniae were detected in ten and five PEs respectively, but with antibiotic treatment these bacteria rapidly became undetectable in 6/10 and 4/5 PEs, respectively. There was a negative correlation between P. aeruginosa numbers and FEV₁ during stable phase (r_s = 0.75, p < 0.05), and reductions in P. aeruginosa load with intravenous antibiotic treatment correlated with improved FEV₁ (r_s = 0.52, p < 0.05).ConclusionsExacerbations are not due to increased P. aeruginosa numbers in CF adults. However, lung function improvements correlate with reduced P. aeruginosa burden suggesting that current antibiotic treatment strategies remain appropriate in most patients. Improved understanding of PE characterised by unchanged P. aeruginosa numbers and minimal lung function improvement following treatment may allow better targeted therapies.     

A network meta-analysis of the efficacy of inhaled antibiotics for chronic Pseudomonas infections in cystic fibrosis

BackgroundVarious inhaled antibiotics are currently used for treating chronic Pseudomonas aeruginosa lung infection in cystic fibrosis (CF) patients, however their relative efficacies are unclear. We compared the efficacy of the inhaled antibiotics tobramycin (TIP, TIS-T, TIS-B), colistimethate sodium (colistin) and aztreonam lysine for inhalation (AZLI) based on data from randomised controlled trials.MethodsIn the base case, efficacies of antibiotics were compared using a network meta-analysis of seven trials including change from baseline in forced expiratory volume in 1 second (FEV₁) % predicted, P. aeruginosa sputum density and acute exacerbations.ResultsThe tobramycin preparations, AZLI and colistin, showed comparable improvements in efficacy in terms of FEV1% predicted at 4 weeks; the difference in % change from baseline (95%CrI) for TIP was compared to TIS-T (- 0.55, - 3.5;2.4), TIS-B (- 0.64, - 7.1;5.7), AZLI (3.64, - 1.0;8.3) and colistin (5.77, - 1.2;12.8).ConclusionWe conclude that all studied antibiotics have comparable efficacies for the treatment of chronic P. aeruginosa lung infection in CF.     

Molecular detection of an atypical,highly resistant,clonal Pseudomonas aeruginosa isolate in cystic fibrosis patients

BackgroundThe identification of Pseudomonas aeruginosa (P. aeruginosa) isolates in sputum from cystic fibrosis (CF) patients can be challenging due to the multitude of phenotypic changes isolates undergo during adaptation to the microenvironment of the CF lung.MethodsWe report the occurrence of shared P. aeruginosa isolates which failed identification by phenotypic methodologies and required species specific polymerase chain reaction. P. aeruginosa isolates were genotyped by macrorestriction analysis.ResultsAnalysis of atypical isolates revealed one clonal P. aeruginosa isolate and three smaller clusters. In contrast molecular typing of phenotypically characteristic P. aeruginosa isolates revealed only small clusters. Despite exhibiting higher levels of antimicrobial resistance, acquisition of atypical strains was not associated with significant changes in clinical decline.ConclusionsOur experience highlights the importance of accurate identification of bacterial isolates in CF lung disease to detect clonal spread of atypical isolates.     

Pseudomonas aeruginosa serology and risk for re-isolation in the EPIC trial

BackgroundThe prognostic value of Pseudomonas aeruginosa serology for antibiotic therapy in cystic fibrosis patients is not well understood.MethodsUsing five antigens from two ELISAs, we assessed whether positive serology in CF patients participating in the multi-center Early Pseudomonas Infection in Children (EPIC) trial would predict treatment failure, time to pulmonary exacerbation and risk for recurrent P. aeruginosa isolation post eradication.ResultsBaseline positive P. aeruginosa serology was not significantly associated with failure of initial P. aeruginosa eradication measured at week 10 (adjusted for baseline culture) but seropositivity to the antigens alkaline protease and exotoxin A was significantly associated with increased risk for recurrent P. aeruginosa isolation during the 60 week post eradication follow-up period (p = 0.003 and p = 0.001 respectively). There was no association between baseline seropositivity and time to pulmonary exacerbation.ConclusionP. aeruginosa serology may complement culture results in clinicians' efforts to successfully monitor recurrence of early P. aeruginosa in CF patients.     

Early treatment with inhaled antibiotics postpones next occurrence of Achromobacter in cystic fibrosis

ObjectivesIn this nationwide retrospective study, we analysed species distribution, antimicrobial susceptibility and time to next occurrence of Achromobacter in Danish cystic fibrosis (CF) patients from 2000 to 2011.MethodsThirty-four primary isolates were identified to species level and subjected to antimicrobial susceptibility testing. Effectiveness of early antimicrobial treatment was assessed by a Kaplan–Meier estimation of time to recurrence.ResultsAchromobacter xylosoxidans accounted for 13 (38%) of the isolates, and an unnamed species accounted for 11 (32%) of the isolates. Meropenem, piperacillin–tazobactam and trimethoprim–sulfamethoxazole were highly active against chemotherapy-naïve Achromobacter, while ceftazidime, colistin and tobramycin were judged adequate for inhalation therapy. Fifty-five percent of 25 patients treated with inhaled ceftazidime, colistin, or tobramycin remained free of Achromobacter three years after acquisition, in contrast to 17% of 22 patients who did not receive inhaled antibiotics (P < 0.01).ConclusionsEarly treatment with inhaled antibiotics may prevent or postpone chronic infection with Achromobacter in CF patients.     

Sinonasal persistence of Pseudomonas aeruginosa after lung transplantation

We report on two CF patients who received double lung transplantation (LTX) due to Pseudomonas aeruginosa related pulmonary destruction. Prior to LTX we detected P. aeruginosa in nasal lavages (NL) and sputum cultures from both patients. Donor lungs of patient 1 became colonized within four weeks with P. aeruginosa identical in genotype with isolates from his pre-transplant sputum cultures and pre- and post-transplant NL.In contrast, patient 2 remained P. aeruginosa free in lower airway samples (bronchial lavage/sputum) for now up to 30 months, despite persistent detection of P. aeruginosa that was identical in genotype with pre-transplant NL and sputum isolates in NL and even in throat swabs. For prevention of pulmonary re-colonization patient 2 has continuously inhaled Colomycin 1 MIU once daily during the preceding more than 36 months with the novel Pari Sinus™ nebulizer, which in scintigraphic studies was shown to deliver vibrating aerosols into paranasal sinuses, additional to bronchial antibiotic inhalation.DiscussionPulmonary colonization of transplanted donor lungs with identical clones previously colonizing the explanted lungs has been described previously and the upper airways were postulated as reservoir for descending colonization. However, this remained speculative, as upper airway sampling which does not belong to current standards, was not performed in these studies.Our report demonstrates persistence of identical P. aeruginosa genotypes in CF upper airways prior to and after LTX underlining risks of descending colonization of transplanted lungs with P. aeruginosa, which increases risks of graft dysfunction. Therefore, we recommend regular assessment of sinonasal colonization prior to and after LTX. Sinonasal inhalation with antimicrobials should be investigated in prospective trials.     

A retrospective analysis of biofilm antibiotic susceptibility testing: A better predictor of clinical response in cystic fibrosis exacerbations

BackgroundBacteria grow as biofilms within CF airways. However, antibiotic susceptibility testing is routinely performed on planktonically-growing bacteria. This study assessed whether CF patients infected with multiresistant organisms had improved clinical outcomes if given antibiotics that inhibited their biofilm-grown bacteria.Methods110 patients with pulmonary exacerbations were treated with intravenous antibiotics based on susceptibility testing of planktonically-growing bacteria. A retrospective analysis was done using bacterial isolates grown from their sputum at exacerbation. Each isolate was grown as a biofilm and combination antibiotic susceptibility testing was performed. Clinical outcomes in patients treated with biofilm-susceptible antibiotics were compared to those that were not.Results66 of 110 patients (60%) were treated with antibiotic combinations that inhibited all of their planktonically-grown bacterial isolates, however, when the same isolates were grown as biofilms, only 24 patients (22%) had all of their biofilm-grown isolates remaining susceptible to the antibiotics (P = < 0.001 ). When patients with at least one biofilm-grown susceptible isolate (n = 61) were compared to those with none (n = 49), there was a significant decrease in sputum bacterial density (P = 0.02) and length of stay (P = 0.04) and a non-significant decrease in treatment failure. Survival analyses of time to next exacerbation showed non-significant trends favoring patients treated with biofilm-effective antibiotics.ConclusionsMost patients with CF exacerbations do not receive antibiotics that inhibit all biofilm-grown bacteria from their sputum at exacerbation. Patients treated with biofilm-effective therapy seemed to have improved clinical outcomes.     

Factors influencing the acquisition of Stenotrophomonas maltophilia infection in cystic fibrosis patients

BackgroundStenotrophomonas maltophilia is one of the most common multi-drug resistant organisms causing pulmonary infections in CF patients. It is unknown whether S. maltophilia infection follows the same pattern and shares similar risk factors for acquisition as described for Pseudomonas aeruginosa.MethodsWe examined all clinical events from 1997 to 2008 in the Toronto CF Database to identify risk factors for the acquisition of S. maltophilia and to define distinct patterns of infection.ResultsWe followed 601 patients over 12 years, during which time one quarter of subjects had at least one positive culture for S. maltophilia; the incidence rate was slightly higher in children (11.6/100 person years) compared with adults (10.6/100 person years). Using multi-variable Cox proportional hazards models, steeper rate of FEV₁ decline was a significant risk factor for S. maltophilia acquisition, whereas new infections were less likely to occur with greater oral antibiotic use and a history of Burkholderia cepacia complex infection.ConclusionsThis study illustrates the evolution of S. maltophilia infection over time in a large cohort of adults and children with CF. Younger CF patients, and those with greater lung function decline were at increased risk of S. maltophilia infection. The use of oral antibiotics to maintain lung function may be a way of decreasing the risk of infection. However, the optimal management of CF patients with persistent S. maltophilia infection is not yet known and requires further studies.     

Diversity of β-lactamases produced by imipenem resistant,Pseudomonas aeruginosa isolates from the bloodstream

IntroductionThe emergence of imipenem non-susceptible Pseudomonas aeruginosa isolates is a matter of great concern because these isolates can become resistant to all available antibiotics. This study conducted to characterize β-lactamase genes in imipenem resistant P. aeruginosa isolates from bloodstream.Methods56 non-duplicate clinical isolates of P. aeruginosa were collected in Tehran hospitals. Antibacterial susceptibility was determined by disk diffusion and MIC methods. ESBL and MBL production was confirmed by combined disk. β-Lactamase classes A, B and D genes were identified by PCR.ResultsSeventeen (30.3%) isolates were imipenem resistant for which 16 isolates simultaneously were resistant to all tested antibiotics. While among 39 imipenem susceptible isolates, only two isolates were resistant to all tested antibiotics. In imipenem resistant isolates, bla_TEM, bla_SHV and bla_OXA-10 were found in 41.1% of isolates and bla_VIM, bla_IMP and bla_PER were identified in 47%, 11.7% and 5.8% of isolates respectively, while in imipenem susceptible isolates, bla_TEM, bla_SHV and bla_OXA-10 were determined in 2.5%, 7.6% and 33.3% of isolates, respectively. The imipenem resistant isolates had been recovered mostly (67.7%) from patients in the Burn hospital.ConclusionThe result of this study indicated the emergence of multidrug resistant MBL and non-MBL producing P. aeruginosa, particularly in the Burn hospital and bla_VIM was dominant β-lactamase genes in imipenem resistant isolates. The isolation of carrier patients may lead to prevent a further dissemination.     

Colistin-based Treatment of Multidrug-resistant Gram-negative Bacterial Pulmonary Infections After Lung Transplantation

Background

Lung transplantation (LT) is a viable option for a select group of patients with end-stage lung disease. However, infections are a major complication after LT, accounting for significant morbidity and mortality. Several germs may be responsible; multidrug-resistant Gram-negative (MDR-GN) bacteria are emerging. Colistin is widely used in the treatment of these infections and is administered by inhalation and/or parenterally. At our institution, in patients with tracheostomy, colistin is administered by direct instillation in the airway during bronchoscopy. We reviewed a series of patients who underwent LT complicated by postoperative MDR-GN bacterial pulmonary infection.

Extensive diversification is a common feature of Pseudomonas aeruginosa populations during respiratory infections in cystic fibrosis

BackgroundPopulations of the Liverpool Epidemic Strain (LES) of Pseudomonas aeruginosa undergo extensive diversification in the cystic fibrosis (CF) lung during long-term chronic infections.MethodsWe analyzed sets of 40 isolates from the sputa of five CF patients, each chronically infected with a different non-LES strain of P. aeruginosa. For each sample (two per patient), diversity was assessed by characterizing nine phenotypic traits.ResultsAll P. aeruginosa populations were highly diverse, with the majority of phenotypic variation being due to within-sample diversity.ConclusionsMaintenance of diverse populations in the CF lung is a common feature of P. aeruginosa infections.     

Bacterial contamination of cystic fibrosis clinics

BackgroundRespiratory pathogens from CF patients can contaminate inpatient settings, which may be associated with increased risk of patient-to-patient transmission. Few data are available that assess the rate of bacterial contamination of outpatient settings. We determined the frequency of contamination of CF clinics and the effectiveness of alcohol-based disinfectants in reducing hand carriage of bacterial pathogens.MethodsWe conducted a point prevalence survey and before–after trial in outpatient clinics at 7 CF centers. The study examined CF patients with positive respiratory cultures for Pseudomonas, Staphylococcus, Stenotrophomonas or Burkholderia species. Hand carriage and environmental contamination with respiratory pathogens were assessed during clinic visits (Part I) and the effectiveness of hand hygiene performed by CF patients (Part II) was determined using molecular typing of recovered isolates.ResultsIn Part I (n = 97), the contamination rate was 13.6%. Pseudomonas and S. aureus, including methicillin-resistant strains, were cultured from patients' hands (7%), the exam room air (8%), and less commonly, environmental surfaces (1%). In Part II (n = 100), the hand carriage rate of pathogens was 13.5% and 4 participants without initial detection of pathogens had hand contamination when recultured at the end of the clinic visit.ConclusionsRespiratory pathogens from CF patients can contaminate their hands and the clinic environment, but the actual risk of patient-to-patient transmission in the outpatient setting remains difficult to quantify. These findings support several recommendations CF infection control recommendations including hand hygiene for staff and patients, contact precautions for certain pathogens, and disinfecting equipment and surfaces touched by patients and staff.     

Influenza B outbreak at an adult cystic fibrosis centre - Clinical impact and factors influencing spread

IntroductionAn outbreak of Influenza B occurred at a large United Kingdom (UK) regional adult cystic fibrosis (CF) centre in May 2016. This was late in the UK 2015–2016 influenza season and occurred on a specialist ward with strict infection control procedures. This study investigates the spread of influenza, clinical consequences and potential contributing factors.MethodsPatient records, clinical status and pulmonary function data were reviewed for all inpatients during this period. Respiratory viral PCR results, influenza vaccination status of patients and staff, and environmental factors were also recorded. Affected patients were prospectively monitored for the following three months.Results10 of 21 inpatients developed influenza B between 5th and 12th May 2016, an attack rate of 48%. All those characterised were confirmed as the same strain of influenza B/Victoria-lineage. Influenza infection resulted in a mean FEV₁ reduction of 10.5% (SD 11.3, p = 0.012), which persisted at 3 months post infection (p = 0.003). Nine of the affected cases rooms were in close proximity on the ward while patients in the two isolation rooms with enhanced ventilation did not become infected. Ventilation measurements in affected rooms ranged from 1.75 to 2.10 air changes/hour, below national recommendations. Seventy percent of affected inpatients had received the 2015/16 trivalent seasonal influenza vaccine, which did not contain a B/Victoria-lineage influenza B virus.ConclusionThis influenza B outbreak in CF adults had a high attack rate and a significant clinical impact. Room ventilation and a limited protection from the seasonal influenza vaccine were possible contributory factors.