Petra Schelstraete

Pseudomonas aeruginosa in the home environment of newly infected cystic fibrosis patients

The source of acquisition of Pseudomonas aeruginosa in cystic fibrosis (CF) patients remains unknown. Patient-to-patient transmission has been well documented but the role of the environment as a source of initial infection is as yet unclear. In the present study, the origin of the first P. aeruginosa isolate in CF patients was investigated by comparing the P. aeruginosa genotype(s) from newly infected patients with genotypes of P. aeruginosa isolates from the home environment and from other patients from the same CF centre. A total of 50 newly infected patients were studied. P. aeruginosa could be cultured from 5.9% of the environmental samples, corresponding to 18 patients. For nine of these, the genotype of the environmental P. aeruginosa isolate was identical to the patients isolate. In total, 72% of the environmental P. aeruginosa isolates were encountered in the bathroom. Patient-to-patient transmission within the CF centre could not be ruled out for three patients. In summary, a low prevalence of Pseudomonas aeruginosa was found in the home environment of the newly infected cystic fibrosis patients. The bathroom should be targeted in any preventive cleaning procedures. An environmental source of the new infection could not be ruled out in nine patients.

Eradication therapy for Pseudomonas aeruginosa colonization episodes in cystic fibrosis patients not chronically colonized by P. aeruginosa.

Pseudomonas aeruginosa (Pa) is one of the most common and clinically important pathogens in patients with cystic fibrosis (CF). Chronic Pa colonization in CF patients is associated with increased morbidity and mortality. Pa strains causing early infection are usually antibiotic sensitive and have low bacterial density in the airways. As a result, the treatment strategy has shifted from suppressive therapy in patients chronically colonized by Pa to attempts at early eradication therapy as soon as Pa is detected. In the literature, different treatment regimens have been studied. However, the optimal treatment regimen and duration of treatment are not yet determined. In this article, an overview on the natural history of early Pa colonization and the history of eradication treatment is given. Moreover, the results of the different eradication treatment trials and directions for future research are discussed.

Polymorphisms in the lectin pathway genes as a possible cause of early chronic Pseudomonas aeruginosa colonization in cystic fibrosis patients.

Genes of innate immunity may be involved in early onset of chronic Pa (Pseudomonas aeruginosa) colonization (cPaC) in cystic fibrosis (CF) patients. We studied 19 single nucleotide polymorphisms (SNPs) in 5 genes coding for proteins of the lectin complement pathway: MBL2 (Mannose binding lectin 2), MASP 1, 2, 3 (MBL-associated serine Protease) and FCN 1, 2 (Ficolin) gene in 96 CF patients. Association survival analysis using different genetic models was performed looking for an association between SNPs and age at onset of cPaC. CF patients who are MBL deficient are earlier chronic Pa colonized compared to MBL sufficient patients. Also patients with MBL2 genotype YO/YO, YO/XA, XA/XA, YA/YO and YA/XA are earlier chronic Pa colonized. CF patients heterozygous or homozygous for mutant alleles of two linked SNPs in the FCN1 gene (rs2989727 and rs1071583) are earlier colonized with Pa. Similarly, earlier onset of Pa colonization is seen in CF patients heterozygous for linked SNPs of FCN2 gene (rs7865453 and rs7851696) and MASP3 gene (rs7851696). Variants in MBL2, FCN1, FCN2 and MASP3 genes are significantly associated with earlier onset of chronic P. aeruginosa colonization.

Neonatal pulmonary interstitial glycogen accumulation disorder

An additional clinicohistopathological observation of neonatal pulmonary interstitial glycogenosis is described, confirming the findings in the original description by Canakis and coworkers [1]. The most striking finding is the presence of glycogen-laden cells within the interstitium of the lung. The outcome is favourable relative to other chronic interstitial lung diseases. We propose an alternative term as ‘‘glycogenosis’’ refers to a group of inborn errors of metabolism that are not related to this disease. A few hours after birth, a term infant developed signs of respiratory distress and was transferred with supplemental oxygen. Congenital heart disease was ruled out. In the hours after admission, the respiratory condition deteriorated and the baby was intubated and treated with surfactant, high frequency oscillation and nitric oxide inhalation for 12 days. Tracheal aspirate showed normal surfactant protein C and B. Chest X-ray films showed progressive hyperinflation and evolution to a mixed interstitial and alveolar pattern. Owing to chronic oxygen dependency and obvious tachypnoea, a high resolution CT scan of the chest was performed on day 55 demonstrating distortion of the lung architecture with the presence of linear opacities, mixed with areas of overinflation/emphysema and ground glass opacity. In the further work-up, cystic fibrosis was excluded and serum alpha-1-antitrypsin was normal. An infectious cause including Chlamydia, adenovirus, coxsackievirus, influenza, parainfluenza, Epstein-Barr virus, cytomegalovirus and Mycoplasma could not be demonstrated. Bacterial cultures remained sterile. A Mantoux test was negative. On day 68, an open lung biopsy was performed. Haematoxylin and eosin stained sections revealed diffuse thickening of the alveolar septae (Fig. 1A,B), while frozen sections showed the presence of abundant glycogen in the cytoplasm of the interstitial cells (Fig. 1C,D). Ultrastructural analysis of lead-contrasted ultrathin sections showed interstitial cells containing intracytoplasmic pools of high contrast granular material compatible with monoparticulate glycogen. Methylprednisolone pulse therapy was initiated at 10 mg/kg per day once daily for 3 days every month. There was no effect on oxygen need after 4 monthly treatments. The child was discharged home on supplemental oxygen at the age of 6 months and steroid therapy was continued monthly. Oxygen requirement decreased gradually and could be stopped at the age of 10 months, as was steroid therapy. He remained well except for a brief hospitalisation at the age of 1 year for a viral respiratory infection and 10 days hospitalisation at the age of 19 months because of bronchiolitis due to respiratory syncytial virus. Canakis and coworkers described seven cases of chronic interstitial lung disease (ILD) presenting with an atypical respiratory disorder during the neonatal period [1]. Most patients were symptomatic within 24 h after birth. Infectious or inflammatory causes of respiratory insufficiency were ruled out. All patients showed uniform histological features: thickened interstitium with immature interstitial cells containing abundant cytoplasmic glycogen. Although cytoplasm of occasional type 2 cells may contain residual aggregates of K. Smets (&) AE P. Vanhaesebrouck Neonatal Intensive Care Unit 1 B1, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium E-mail: koenraad.smets@ugent.be Tel.: +32-9-2403535 Fax: +32-9-2406105

Disseminated Mycobacterium avium Infection in a Patient with a Novel Mutation in the Interleukin-12 Receptor-β1 Chain

A girl with relapsing cervical lymphadenopathy due to Mycobacterium avium subsequently developed abdominal adenopathy and intestinal inflammation. 1 known (c.1623_1624delGCinsTT) and 1 novel mutation (c.65_68delCTGC of exon2) of the Interleukin-12 Receptor-beta1 (IL-12Rbeta1) gene was detected. Unlike reports of a more favorable outcome in these patients, our patient died of severe intestinal involvement.

Genotype based evaluation of Pseudomonas aeruginosa eradication treatment success in cystic fibrosis patients

BACKGROUND Longitudinal data regarding the genotypes of Pseudomonas aeruginosa isolates after eradication treatment are limited. We followed cystic fibrosis patients after a first ever isolation of P. aeruginosa and evaluated the P. aeruginosa-free time period after eradication therapy. METHODS Between January 2003 and December 2008 respiratory samples were cultured prospectively from 41 patients with a first ever P. aeruginosa isolate. Twenty five patients had at least one subsequent isolate. Treatment efficacy was assessed based on the time to a second isolation and on comparison of the RAPD genotypes of the P. aeruginosa isolates. RESULTS Eleven patients became chronically colonized during the study period. For ten of these the second isolate had the same genotype as the first isolate. Moreover, these patients had a significantly shorter P. aeruginosa-free time interval between the first ever and the second isolate compared to the 14 not chronically colonized patients (median 0 months versus 7.5 months, p<0.05). CONCLUSION Our results indicate that the presence of a genotypically identical subsequent P. aeruginosa isolate and/or a short P. aeruginosa-free time interval after treatment are ominous signs and might be useful additional tools to predict impending chronic colonization. Current routine bacteriological methods for the detection of P. aeruginosa may lack the sensitivity to discriminate between true eradication and low bacterial persistence.

Streptococcal pharyngitis in children: to treat or not to treat?

Controversy remains about the need for antibiotic therapy of group A streptococcal (GAS) pharyngitis in high-resource settings. Guidelines on the management of GAS pharyngitis differ considerably, especially in children. We performed a literature search on the diagnosis and treatment of GAS pharyngitis in children and compared different guidelines with current epidemiology and the available evidence on management. Some European guidelines only recommend antibiotic treatment in certain high-risk patients, while many other, including all American, still advise antimicrobial treatment for all children with GAS pharyngitis, given the severity and re-emerging incidence of complications. Empirical antimicrobial treatment in children with sore throat and a high clinical suspicion of GAS pharyngitis will still result in significant overtreatment of nonstreptococcal pharyngitis. This is costly and leads to emerging antibiotic resistance. Early differential diagnosis between viral and GAS pharyngitis, by means of a ‘rapid antigen detection test’ (RADT) and/or a throat culture, is therefore needed if ‘pro treatment’ guidelines are used. Conclusion: Large scale randomized controlled trials are necessary to assess the value of antibiotics for GAS pharyngitis in high-resource countries, in order to achieve uniform and evidence-based guidelines. The severity and the possibly increasing incidence of complications in school-aged children suggests that testing and treating proven GAS pharyngitis can still be beneficial.

Comparison of culture and qPCR for the detection of Pseudomonas aeruginosa in not chronically infected cystic fibrosis patients

BackgroundPseudomonas aeruginosa is the major respiratory pathogen causing severe lung infections among CF patients, leading to high morbidity and mortality. Once infection is established, early antibiotic treatment is able to postpone the transition to chronic lung infection. In order to optimize the early detection, we compared the sensitivity of microbiological culture and quantitative PCR (qPCR) for the detection of P. aeruginosa in respiratory samples of not chronically infected CF patients.ResultsIn this national study, we followed CF patients during periods between 1 to 15 months. For a total of 852 samples, 729 (86%) remained P. aeruginosa negative by both culture and qPCR, whereas 89 samples (10%) were positive by both culture and qPCR.Twenty-six samples were negative by culture but positive by qPCR, and 10 samples were positive by culture but remained negative by qPCR. Five of the 26 patients with a culture negative, qPCR positive sample became later P. aeruginosa positive both by culture and qPCR.ConclusionBased on the results of this study, it can be concluded that qPCR may have a predictive value for impending P. aeruginosa infection for only a limited number of patients.

Sampling and decontamination method for culture of nontuberculous mycobacteria in respiratory samples of cystic fibrosis patients

ABSTRACT We confirmed that chlorhexidine decontamination yielded more nontuberculous mycobacteria than did the N-acetyl-l-cysteine-NaOH-oxalic acid procedure from respiratory samples of cystic fibrosis patients on solid cultures. However, this improved recovery is mostly balanced if the latter is combined with liquid culture. Furthermore, none of the 145 cough swabs, used to sample young children, cultured positive, suggesting that swabs are low-quality samples.

Genetic variations in toll-like receptor pathway and lung function decline in Cystic fibrosis patients

The toll-like receptor (TLR) family maintains pulmonary homeostasis by pathogen recognition, clearance and regulation of inflammation. Genes affecting inflammation response play a key role in modifying Cystic fibrosis (CF) lung disease severity. We assessed the impact of single nucleotide polymorphisms (SNPs) of TLR genes (TLR1 to TLR10, CD14, lipopolyssacharide-binding protein (LBP)) on lung function in CF patients. Each SNP was tested for time-dependent effect on FEV1, using six genetic models. In addition, we investigated associations between SNP genotypes and extreme subject specific slopes of FEV1 decline. Variant alleles of polymorphisms of TLR2 rs1898830, rs5743708, and rs3804100 demonstrated a consistent association with lung disease severity (p = 0.008, p = 0.006 and p = 0.029 respectively). Patients homozygous for variant C allele of TLR5 polymorphism rs5744174 are more frequently associated with extreme fast FEV1 decline (OR: 20 (95% Confidence Interval:1.85-216.18)). Patients homozygous AA for TLR1 polymorphism rs5743551 are more frequently associated with faster decline of FEV1 compared to heterozygous genotype (OR:7.33 (95% CI:1.63-33.11). Our findings indicate that variations in TLR1, TLR2 and TLR5 genes may influence CF lung function decline. Further functional analysis is required to provide new insights into the pathogenesis of TLRs in CF lung disease severity.