Rb Gore

High-frequency Triazole Resistance Found In Nonculturable Aspergillus fumigatus from Lungs of Patients with Chronic Fungal Disease

BACKGROUND Oral triazole therapy is well established for the treatment of invasive (IPA), allergic (ABPA), and chronic pulmonary (CPA) aspergillosis, and is often long-term. Triazole resistance rates are rising internationally. Microbiological diagnosis of aspergillosis is limited by poor culture yield, leading to uncertainty about the frequency of triazole resistance. METHODS Using an ultrasensitive real-time polymerase chain reaction (PCR) assay for Aspergillus spp., we assessed respiratory fungal load in bronchoalveolar lavage (BAL) and sputum specimens. In a subset of PCR-positive, culture negative samples, we further amplified the CYP51A gene to detect key single-nucleotide polymorphisms (SNPs) associated with triazole resistance. RESULTS Aspergillus DNA was detected in BAL from normal volunteers (4/11, 36.4%) and patients with culture or microscopy confirmed IPA (21/22, 95%). Aspergillus DNA was detected in sputum in 15 of 19 (78.9%) and 30 of 42 (71.4%) patients with ABPA and CPA, compared with 0% and 16.7% by culture, respectively. In culture-negative, PCR-positive samples, we detected triazole-resistance mutations (L98H with tandem repeat [TR] and M220) within the drug target CYP51A in 55.1% of samples. Six of 8 (75%) of those with ABPA and 12 of 24 (50%) with CPA had resistance markers present, some without prior triazole treatment, and in most despite adequate plasma drug concentrations around the time of sampling. CONCLUSIONS The very low organism burdens of fungi causing infection have previously prevented direct culture and detection of antifungal resistance in clinical samples. These findings have major implications for the sustainability of triazoles for human antifungal therapy.

Novel immunologic classification of aspergillosis in adult cystic fibrosis

BACKGROUND Patients with cystic fibrosis (CF) demonstrate a wide range of hypersensitivity responses to Aspergillus, beyond allergic bronchopulmonary aspergillosis, which require classification. OBJECTIVE This study integrated 2 new methods of Aspergillus detection-sputum galactomannan (GM) and real-time PCR-alongside established serologic markers, to reclassify aspergillosis in CF. METHODS A total of 146 adult patients with CF had serologic tests (ImmunoCap total IgE, specific Aspergillus fumigatus IgE, and specific A fumigatus IgG), sputum real-time Aspergillus PCR, and sputum GM. Patients were classified by using latent class analysis. RESULTS Both RT-PCR and GM were more sensitive than culture in detecting Aspergillus in sputum (culture 37%, RT-PCR 74%, and GM 46%). Intraassay and interassay reproducibility of PCR and GM was excellent. Latent class analysis of triazole-naive patients identified a nondiseased group and 3 disease classes: class 1 (n = 49, 37.7%) represented patients with or without positive RT-PCR but no immunologic response to A fumigatus and negative GM (nondiseased); class 2 (n = 23, 17.7%) represented patients with positive RT-PCR, elevated total and specific A fumigatus IgE/IgG, and positive GM (serologic allergic bronchopulmonary aspergillosis); class 3 (n = 19, 14.6%) represented patients with or without positive RT-PCR, elevated A fumigatus IgE (not IgG), and negative GM (Aspergillus sensitized); and class 4 (n = 39, 30%) represented patients with positive RT-PCR, elevated A fumigatus IgG (not IgE), and positive GM (Aspergillus bronchitis). CONCLUSIONS Three distinct classes of aspergillosis in CF were identified by latent class analysis by using serologic, RT-PCR, and GM data. This novel classification will facilitate improved phenotyping, pathogenesis studies, and management evaluations.

Controlling indoor allergens

OBJECTIVES Reading of this article reinforces the readers knowledge of the role of allergen exposure in relation to asthma and its severity, as well as the relevance of allergen avoidance in the treatment of asthma. DATA SOURCES Initial literature search for existing evidence-based guidelines, reviews, and meta-analyses was carried out, and further literature searches were performed to review individual randomized controlled trials. Evidence level was graded according to the Scottish Intercollegiate Guidelines Network recommendations. RESULTS There is good evidence for the link between mite and cockroach allergen exposure and sensitization, and between sensitization and asthma. For pet allergens, some studies found that exposure to pets in early life was associated with specific immunoglobulin E sensitization and allergic disease later in childhood, whereas others reported a protective effect. The effectiveness of allergen reduction in the treatment of asthma is suggested by studies in which the patients improve substantially when moved into the low-allergen environment of hospitals or high-altitude sanatoria. Because of limitations in the design of the most clinical of studies, we do not yet have a conclusive answer on the effectiveness of domestic aeroallergen avoidance. CONCLUSIONS Minimizing the impact of identified environmental risk factors is an important first step to reduce the severity of asthma. Although environmental control is difficult, it should be an integral part of the overall management of sensitized patients. However, what is unclear is which patients would benefit and by how much, and whether the intervention is cost-effective. These questions will be answered satisfactorily only by large randomized trials.

Air filtration units in homes with cats: can they reduce personal exposure to cat allergen?

Background Domestic air filtration units have previously been shown to cause a dramatic fall in airborne pet allergen levels in homes with pets. Clinical trials of air filtration units, however, have failed to reveal a significant beneficial effect. Personal pet allergen exposure during air filtration unit use has never been measured.

Personal exposure to house dust mite allergen in bed: nasal air sampling and reservoir allergen levels

Background Assessment of personal exposure to dust mite allergen has relied on proxy measures. Only recently has a means to directly measure inhaled allergen particle number become available (the intra‐nasal air sampler).

High-efficiency vacuum cleaners increase personal mite allergen exposure, but only slightly

Background:  High‐efficiency particulate‐arrest‐filter vacuum cleaners are recommended to allergy sufferers although their use increases personal cat allergen exposure. We aimed to measure personal mite allergen exposure during vacuum cleaning by nasal air sampling and to compare exposures while vacuuming and emptying the vacuum cleaner bag.

Isoelectrophoretic patterns of Der p 2 isoforms in house dust from different homes

Abstract Rationale Relative environmental exposures to different allergen isoforms are unknown. We aimed to determine the prevalence of different isoforms of the mite allergen Dermatophagoides pteronyssinus Der p 2 in house dust from different homes. Methods Mattress reservoir dust from 10 different homes was extracted. Eluates were concentrated by spin-filtration, separated by polyacrylamide gel (PAGE) isoelectric focusing and immunoblotted. Der p 2 isoforms were detected by the monoclonal antibody alphaDpX and a chemiluminescence-based reporter system. Radiographs were scanned, analyzed by standard densitometry software and the number and relative motilities of bands were compared between samples. Band molecular mass was estimated by PAGE. Recombinant isoforms rDer p 2.0101, rDer p 2.0102 and rDer p 2.0103 were used as standards, run on PAGE-isoelectric focusing and then analyzed by denaturing gel isoelectric focusing. Results Isoelectric focusing and immunoblotting: Multiple bands were detectable in house dust samples (range 3-8 bands). Relative band motility was similar; up to 5 different bands were common to samples from different homes. Native gel electrophoresis: Der p 2 had a tendency to form dimers and trimers. Denaturing gel electrophoresis of Der p 2 recombinant isoforms: Each isoform demonstrated a tendency to form 2 or 3 bands which could not easily be resolved under stringent conditions (6M urea). Conclusions Polyacrylamide gel isoelectric focusing indicates the presence of multiple Der p 2 isoforms in dust extracts. Some of the observed bands may represent multimeric complexes of Der p 2. Future studies to determine environmental exposure to different isoforms should take this into account.

HEPA air filtration units in homes with cats: Can they reduce personal exposure to cat allergen?

BACKGROUND Domestic air filtration units have previously been shown to cause a dramatic fall in airborne pet allergen levels in homes with pets. Clinical trials of air filtration units, however, have failed to reveal a significant beneficial effect. Personal pet allergen exposure during air filtration unit use has never been measured. OBJECTIVE To determine the effect of air filtration on inhaled cat allergen exposure in homes with cats. METHODS Nasal air samplers were worn to measure personal cat allergen exposure. The study was carried out in five homes with cats on 4 separate days examining four experimental conditions (cat absent or present, air filtration off or on). The two operators collected four baseline samples and two 15-min samples/h over three consecutive hours. Cat allergen-bearing particles were detected by immunoblotting and allergen concentrations measured by amplified enzyme-linked immunosorbent assay (ELISA). RESULTS There was a significant reduction in the quantity of the inhaled Fel d 1 when the air cleaner was used with the cat in the room. Fel d 1 halo counts (detransformed means) were 29.3 at baseline, 11.8 after 1 h, 10.0 after 2 h and 14.1 after 3 h, with no change on control days (P = 1.00). With the cat elsewhere in the house, a marginal, but statistically significant reduction was observed only after 3 h with the use of air cleaner (Fel d 1 halo count: baseline 12.4; 3 h 5.5; P = 0.01). CONCLUSIONS The use of air filtration units appears to result in a much smaller reduction of inhaled cat allergen exposure than suggested by previous studies using standard air samplers. Cat removal remains the best advice to cat-allergic patients who experience symptoms upon exposure.