Improved Standardization of the Bio-Rad Platelia Aspergillus Galactomannan Antigen Sandwich Enzyme Immunoassay Using the DS2 (Dynex) Enzyme-Linked Immunosorbent Assay (ELISA) Processing System.

The galactomannan enzyme immunoassay (GM-EIA) is widely utilized for the diagnosis of invasive aspergillosis (IA). There is inconsistent reproducibility of results between centers when the assay is processed manually. Automation of EIAs can reduce variation. This study investigated the semiautomation of the GM-EIA on the DS2 (Dynex) platform in the following three stages: (i) DS2 GM-EIA method validation with experimental samples, (ii) DS2 retesting of case-defined clinical samples, and (iii) a 12-month audit of DS2 GM-EIA performance. In stage i, Bland-Altman analysis demonstrated a reduced variance between optical density index (ODI) values for samples processed on two DS2 platforms (mean difference, -0.02; limits of agreement [LOA], -0.19 to 0.14) compared with the variance between samples processed manually and on a DS2 platform (mean difference, 0.02; LOA, -0.25 to 0.3). In stage ii, 100% (14/14 samples) qualitative agreement was observed for serum samples from patients with IA, with no significant change in the ODI values when samples were processed on the DS2 platform. A significant decrease in ODI values was observed for control serum samples on the DS2 platform (difference, 0.01; P = 0.042). In stage iii, a significant reduction in the frequency of equivocal results, from 5.56% (136/2,443 samples) to 1.56% (15/961 samples), was observed after DS2 automation (difference, 4.0%; 95% confidence interval [CI], 2.7 to 5.2%; P < 0.01), with an equivalent increase in negative results. This study demonstrates that GM-EIA automation may reduce intersite variability. Automation does not have an impact on the repeatability of truly positive results but contributes to a reduction in false-positive (equivocal) GM-EIA results, reducing the need to retest a significant proportion of samples.

Comparative analysis of Gram's stain, PNA-FISH and Sepsityper with MALDI-TOF MS for the identification of yeast direct from positive blood cultures.

Fungaemia diagnosis could be improved by reducing the time to identification of yeast from blood cultures. This study aimed to evaluate three rapid methods for the identification of yeast direct from blood cultures; Gram's stain analysis, the AdvanDX Peptide Nucleic Acid in Situ Hybridisation Yeast Traffic Light system (PNA-FISH YTL) and Bruker Sepsityper alongside matrix-assisted laser desorption ionisation time of flight mass spectrometry (MALDI-TOF MS). Fifty blood cultures spiked with a known single yeast strain were analysed by blinded operators experienced in each method. Identifications were compared with MALDI-TOF MS CHROMagar Candida culture and ITS rRNA sequence-based identifications. On first attempt, success rates of 96% (48/50) and 76% (36/50) were achieved using PNA-FISH YTL and Gram's stain respectively. MALDI-TOF MS demonstrated a success rate of 56% (28/50) when applying manufacturer's species log score thresholds and 76% (38/50) using in-house parameters, including lowering the species log score threshold to >1.5. In conclusion, PNA-FISH YTL demonstrated a high success rate successfully identifying yeast commonly encountered in fungaemia. Sepsityper(™) with MALDI-TOF MS was accurate but increased sensitivity is required. Due to the misidentification of commonly encountered yeast Gram's stain analysis demonstrated limited utility in this setting.

Evaluation of PNA-FISH yeast traffic light for rapid identification of yeast directly from positive blood cultures and assessment of clinical impact.

The PNA-FISH Yeast Traffic Light assay was performed on 54 clinical isolates of yeasts inoculated into blood culture bottles. The assay showed high sensitivity (Candida albicans/C. parapsilosis, 100%; C. glabrata/C. krusei, 92.3%; C. tropicalis, 100%) and specificity (C. albicans/C. parapsilosis, 100%; C. glabrata/C. krusei, 94.8%; C. tropicalis, 100%). Case note review estimated a change in therapy in 29% of cases had the PNA-FISH result been available to the clinician.

Diagnosis and management of Aspergillus diseases: executive summary of the 2017 ESCMID-ECMM-ERS guideline.

The European Society for Clinical Microbiology and Infectious Diseases, the European Confederation of Medical Mycology and the European Respiratory Society Joint Clinical Guidelines focus on diagnosis and management of aspergillosis. Of the numerous recommendations, a few are summarized here. Chest computed tomography as well as bronchoscopy with bronchoalveolar lavage (BAL) in patients with suspicion of pulmonary invasive aspergillosis (IA) are strongly recommended. For diagnosis, direct microscopy, preferably using optical brighteners, histopathology and culture are strongly recommended. Serum and BAL galactomannan measures are recommended as markers for the diagnosis of IA. PCR should be considered in conjunction with other diagnostic tests. Pathogen identification to species complex level is strongly recommended for all clinically relevant Aspergillus isolates; antifungal susceptibility testing should be performed in patients with invasive disease in regions with resistance found in contemporary surveillance programmes. Isavuconazole and voriconazole are the preferred agents for first-line treatment of pulmonary IA, whereas liposomal amphotericin B is moderately supported. Combinations of antifungals as primary treatment options are not recommended. Therapeutic drug monitoring is strongly recommended for patients receiving posaconazole suspension or any form of voriconazole for IA treatment, and in refractory disease, where a personalized approach considering reversal of predisposing factors, switching drug class and surgical intervention is also strongly recommended. Primary prophylaxis with posaconazole is strongly recommended in patients with acute myelogenous leukaemia or myelodysplastic syndrome receiving induction chemotherapy. Secondary prophylaxis is strongly recommended in high-risk patients. We strongly recommend treatment duration based on clinical improvement, degree of immunosuppression and response on imaging.

Validation and clinical application of molecular methods for the identification of molds in tissue.

BACKGROUND: Invasive fungal infections due to less-common molds are an increasing problem, and accurate diagnosis is difficult. METHODS: We used our previously established molecular method, which allows species identification of molds in histological tissue sections, to test sequential specimens from 56 patients with invasive fungal infections who were treated at our institution from 1982 to 2000. RESULTS: The validity of the method was demonstrated with the establishment of a molecular diagnosis in 52 cases (93%). Confirmation of the causative organism was made in all cases in which a mold had been cultured from the tissue specimen. Less-common molds were identified in 7% of cases and appear to be an increasing problem. CONCLUSIONS: Our previously established method has proven to be of value in determining the incidence of invasive infection caused by less-common molds. Institutions should continue to pursue diagnosis of invasive fungal infections by means of tissue culture and microbiologic analysis.

Early invasive fungal infections and colonization in patients with cirrhosis admitted to the intensive care unit.

Bacterial infections in cirrhosis are common and associated with increased mortality, but little is known about fungal infections. The aim of this study, a sub-analysis of the Fungal Infection Risk Evaluation study, was to assess the incidence and implications of early invasive fungal disease (IFD) in patients with cirrhosis admitted to intensive care units (ICU). Clinical and laboratory parameters collected in the first 3 days of ICU stay for 782 patients with cirrhosis and/or portal hypertension were analysed and compared with those of 273 patients with very severe cardiovascular disease (CVD). The CVD patients had more co-morbidities and higher APACHE II scores. The overall incidence of IFD was similar in the two groups, but the incidence of IFD in ICU was higher in liver patients (1% versus 0.4%; p 0.025) as was fungal colonization (23.8% versus 13.9%; p 0.001). The ICU and in-hospital mortality, and length of stay were similar in the two groups. A higher proportion of liver patients received antifungal therapy (19.2% versus 7%; p <0.0005). There was no difference in mortality between colonized patients who received antifungal therapy and colonized patients who did not. The incidence of IFD in patients with cirrhosis in ICU is higher compared with another high-risk group, although it is still very low. This risk might be higher in patients with advanced liver disease admitted with acute-on-chronic liver failure, and this should be investigated further. Our data do not support prophylactic use of antifungal therapy in cirrhosis.

Toxoplasmosis in bone marrow transplantation: a report of two cases and systematic review of the literature.

Toxoplasma infection represents a rare but often fatal complication in bone marrow transplant (BMT) recipients. We report two cases of toxoplasmosis: one of successfully treated cerebral toxoplasmosis after peripheral blood stem cell transplantation, and a fatal case of pulmonary toxoplasmosis in a BMT recipient. We have systematically reviewed the 110 published cases of toxoplasmosis following BMT. We analyzed the pre-transplant and clinical features of BMT recipients developing toxoplasmosis, together with the diagnostic procedures used and treatment given. By univariate and multivariate statistical analysis we analyzed the risk factors for diagnosis (during life vs post-mortem) and Toxoplasma-related mortality. Ante-mortem diagnosis was made in 47% of cases. Site of infection (P = 0.02; odds ratio 10.8), presence of symptoms at onset (P = 0.01) and conditioning regimen (P = 0.04) were factors influencing whether the diagnosis was made before or after death. Overall mortality rate was 80% and that attributed to toxoplasmosis was 66%. Variables influencing outcome were: site of infection (P = 0.02; odds ratio 5.28), day of onset (P = 0.04) and conditioning regimen (P = 0.04). Underlying disease (P = 0.02; odds ratio 9.45), among patients diagnosed before death, was the most significant factor influencing outcome.

Fusarium dimerum infection in a stem cell transplant recipient treated successfully with voriconazole.

We report the first case, to our knowledge, of a proven Fusarium dimerum soft-tissue infection in a stem cell transplant recipient treated successfully with voriconazole. There is a well-documented increase in the incidence, diversity and antifungal resistance of invasive mould infections in the immunocompromised patient population. The management of these infections is changing as new, more efficacious and less toxic antifungal agents become available. We present the case of a 19-year-old female diagnosed with a proven F. dimerum soft-tissue infection of the foot and possible pulmonary infection with the same organism 10 days following a sibling allogeneic stem cell transplant for severe aplastic anaemia. The infection developed despite treatment with 3 mg/kg AmBisome for a concurrent chest infection. She was treated successfully with voriconazole.

Fatal invasive cerebral Absidia corymbifera infection following bone marrow transplantation.

A 56-year-old dairy farmer received a fully HLA matched unrelated donor marrow transplant for high risk CML in chronic phase. His early post-transplant course was complicated by a series of massive intracerebral bleeds and by sepsis related to a malignant otitis externa. The microbial pathogen isolated from ear swabs was found to be Absidia corymbifera, but CT scan at the time showed no intracerebral extension. Despite neutrophil engraftment and aggressive antifungal management he succumbed. Autopsy revealed invasion of Absidia into the brain from the ear. We speculate that colonisation by Absidia resulted from occupational exposure.

Bacteriological evaluation of a down-draught necropsy table ventilation system.

AIMS: To evaluate the microbiological efficacy of a down-draught necropsy table ventilation system (which surrounds the cadaver with a "curtain" of air under continuous extraction) during post mortem procedures. METHODS: Air sampling was carried out both in the presence and absence of staff and cadaver and during a full post mortem procedure, with functioning and non-functioning table air extraction. The penetration of the air "curtain" was also examined during the use of an oscillating bone saw by means of a tracer organism, Bacillus subtilis var niger, painted on to the skull. RESULTS: There was little difference between bacterial counts obtained in the presence of staff only, staff plus cadaver, or during a post mortem examination. With all counts obtained, however, there was a two to three-fold reduction when the ventilation was in operation compared with when the extract duct was occluded. Using the tracer organism, a two to three log reduction in counts was shown when the "curtain" was in operation during the use of the oscillating bone saw. CONCLUSIONS: These results suggest that the system provides potential protection for post mortem room staff against airborne infections.

Carriage of Candida species and C albicans biotypes in patients undergoing chemotherapy or bone marrow transplantation for haematological disease.

Six hundred and seventy four yeast isolates obtained from routine microbiological screening of 153 patients with haematological disease were identified and Candida albicans isolates biotyped over nine months to determine longitudinal and cross sectional patterns of yeast colonisation. A yeast microflora persisted in many patients despite the routine prophylactic use of oral antifungal agents. Analysis of the yeast species isolated on a cross sectional basis showed that C albicans accounted for 65% of yeasts isolated from the oral cavity but only 45% of the faecal yeast flora. Longitudinal changes in yeast flora occurred significantly more often in faecal samples than in oral samples and significantly less often in sites colonised with C albicans than in sites colonised with other species. No associations were found between the yeasts isolated and the nature of antifungal prophylaxis used, or the extent of a patient's stay in hospital.

Chaetomium pneumonia in patient with acute myeloid leukaemia.

A patient with relapsed refractory acute myeloid leukaemia developed typical fungal lung lesions despite intravenous amphotericin B prophylaxis. Chaetomium globosum was cultured from the resected right lower lobe. Histology showed branching hyphae negative for common Aspergillus species by immunohistochemical staining. Previous reports of invasive disease caused by Chaetomium and some applications of immunohistochemical staining for Aspergillus are discussed.

Iron state and hepatic disease in patients with thalassaemia major, treated with long term subcutaneous desferrioxamine.

Liver biopsies were performed on 51 regularly transfused patients with beta thalassaemia, age range 5-36 (mean 18.6) years, who had received regular subcutaneous desferrioxamine (DFX) treatment for periods between one and eight years (40 for eight years). The biopsy specimens were examined by light microscopy and immunofluorescence for hepatitis B virus surface and core antigens (HBsAg and HBcAg), and the iron content was determined chemically. The results were compared with serum ferritin concentration and aspartate transaminase (AST) activity and with hepatitis B virus serology. Biopsy specimens, in which chemical liver iron had been determined in 12, were also available from 17 patients. Mean serum ferritin (+/- SD) had fallen from 5885 (3245) micrograms/l to 1638 (976) micrograms/l in 36 patients after eight years' chelation, while mean (+/- SD) liver iron concentration had fallen from 2945 (900) micrograms/100 mg dry weight to 857 (435) micrograms/100 mg dry weight in 12 of them. All biopsy specimens examined were negative for HBs and HBc antigens. The presence of histological features of hepatitis was associated with increased liver iron content, increased fibrosis, and with progression of fibrosis between the two biopsies. Procollagen III peptide was assayed in 28 patients but did not correlate with the degree of hepatitis, fibrosis, or with chemical liver iron content. We conclude that with regular subcutaneous DFX, mean concentrations of serum ferritin and liver iron are maintained in these patients at about five and 10 times the normal value, respectively, and that progression of liver damage is more likely to be due to viral hepatitis, presumably related to the parenterally transmitted non-A, non-B agents than to iron overload.

An evaluation of the cost-effectiveness of using CHROMagar for yeast identification in a routine microbiology laboratory.

CHROMagar, a chromogenic differential culture medium, is claimed to facilitate the isolation and presumptive identification of certain clinically important yeast species, e.g., Candida albicans. This study evaluated the cost-effectiveness and time advantage of using it in comparison with Sabouraud dextrose agar (SDA). Three possible pathways, each of which included the use of one or both media, were compared in a routine laboratory. A total of 21 yeast isolates was cultured from 298 clinical samples from neutropenic and AIDS patients. An overall sensitivity of 95.2% was observed for each medium and primary isolation on CHROMagar was found to be 100% sensitive and 100% specific for C. albicans. For identification purposes, after initial culture the use of CHROMagar provided the most economical and least time-consuming method. Direct inoculation on to CHROMagar is recommended for blood cultures when yeast cells are seen on microscopy and where early appropriate therapy is imperative.

Systematic review of isolation policies in the hospital management of methicillin-resistant Staphylococcus aureus: a review of the literature with epidemiological and economic modelling.

OBJECTIVE: To review the evidence for the effectiveness of different isolation policies and screening practices in reducing the incidence of methicillin-resistant Staphylococcus aureus (MRSA) colonisation and infection in hospital in-patients. To develop transmission models to study the effectiveness and cost-effectiveness of isolation policies in controlling MRSA. DATA SOURCES: MEDLINE, EMBASE, CINAHL, The Cochrane Library and SIGLE (1966-2000). Hand-searching key journals. No language restrictions. REVIEW METHODS: Key data were extracted from articles reporting MRSA-related outcomes and describing an isolation policy in a hospital with epidemic or endemic MRSA. No quality restrictions were imposed on studies using isolation wards (IW) or nurse cohorting (NC). Other studies were included if they were prospective or employed planned comparisons of retrospective data. Stochastic and deterministic models investigated long-term transmission dynamics, studying the effect of a fixed capacity IW, producing economic evaluations using local cost data. RESULTS: A total of 46 studies were accepted: 18 IWs, 9 NC, 19 other isolation policies. Most were interrupted time series, with few planned formal prospective studies. All but one reported multiple interventions. Consideration of potential confounders, measures to prevent bias, and appropriate statistical analysis were mostly lacking. No conclusions could be drawn in a third of studies. Most others provided evidence consistent with reduction of MRSA acquisition. Six long interrupted time series provided the strongest evidence. Four of these provided evidence that intensive control measures which included patient isolation were effective in controlling MRSA. In two others IW use failed to prevent endemic MRSA. There was no robust economic evaluation. Models showed that improving the detection rate or ensuring adequate isolation capacity reduced endemic levels, with substantial savings achievable. CONCLUSIONS: Major methodological weaknesses and inadequate reporting in published research mean that many plausible alternative explanations for reductions in MRSA acquisition associated with interventions cannot be excluded. No well-designed studies allow the role of isolation measures alone to be assessed. Nonetheless, there is evidence that concerted efforts that include isolation can reduce MRSA even when endemic. Little evidence was found to suggest that current isolation measures recommended in the UK are ineffective, and these should continue to be applied until further research establishes otherwise. The studies with the strongest evidence, together with the results of the modelling, provide testable hypotheses for future research. Guidelines to facilitate design of future research are produced.

Infections in liver transplantation: risk factors and strategies for prevention.

Infection affects up to 70% of liver transplant recipients and is the second most common complication after rejection and graft dysfunction. Identified risk factors for infection include: previous transplantation; type of biliary anastomosis; transfusion requirements at surgery; surgical complications; duration of operation; duration of postoperative ventilation; serological status of donor and recipient; steroid use and serotherapy for rejection; and pre- and post-transplant antibiotic usage. The majority of symptomatic infections are bacterial and relate to surgery (intra-abdominal, biliary and wound infections), ventilation and intravenous cannulae. Cytomegalovirus infections occur in 45-100% of recipients but are asymptomatic in the majority. Fungal infections are mostly due to Candida albicans but infections due to Aspergillus spp. occur in approximately 6% and carry a high mortality. There are very few prospective comparative trials of antimicrobial prophylaxis in this patient population. The management of these patients needs to be based on such studies.

Endoscopic decontamination: an audit and practical review.

A comprehensive audit of endoscopic decontamination practices throughout a 1200-bedded teaching hospital trust was undertaken, prior to a review of the current policy and consideration of alternative disinfectants. Pharmacy records of glutaraldehyde usage, occupational health staff survey data of glutaraldehyde exposure, discussions with all departments where endoscopy might be conducted and information from all companies supplying endoscopes and allied equipment were reviewed. In total, 56 endoscopes were found to be in use in 16 areas of the Trust. In the main designated endoscopy units, compliance with the established policy was generally good, but in other areas, equipment which could tolerate autoclaving was being disinfected with chemical sterilants; some units were still using endoscopes which were not fully immersible and there was widespread use of disinfectant troughs, rather than automated washer-disinfectors. In most cases, this was because staff were concerned about endoscopy equipment passing to a central processing department with potential delays and losses. An updated Trust-wide endoscopy policy, using glutaraldehyde and incorporating the current British Thoracic Society, British Gastroenterological Society and British Urological Society guidelines, has now been implemented. The issues around this and alternative disinfectants are discussed.

The epidemiology and prevention of invasive aspergillosis.

Over the past two decades, the incidence of invasive aspergillosis (IA) has risen inexorably. This is almost certainly the consequence of the more widespread use of aggressive cancer chemotherapy regimens, the expansion of organ transplant programmes and the advent of the acquired immunodeficiency syndrome (AIDS) epidemic. Despite the development of new approaches to therapy, IA still remains a life-threatening infection in immunocompromised patients and is the most important cause of fungal death in cancer patients. It is clear that the prevention of severe fungal infection by the use of effective infection control measure should be the priority of the teams involved in managing at-risk patients. The evidence from clinical and molecular epidemiological studies is reviewed and current thinking on sources and routes of transmission of the organism are discussed. Our increasing understanding of these has led to the development of a variety of environmental and general strategies for the prevention of IA. It is anticipated that these, coupled with the use of prophylactic antifungal agents active against Aspergillus spp., will have a significant impact upon the morbidity and mortality associated with this infection.

The effect of increased bed numbers on MRSA transmission in acute medical wards.

An 18-month prospective survey was performed to examine the effect of adding a fifth bed to four-bedded bays in three acute medical wards on colonization by methicillin-resistant Staphylococcus aureus (MRSA). Screening procedures were in accordance with the UK national guidelines. All patients newly colonized with MRSA were visited, and their bed location determined. Data from the five-bedded bays were compared with those from four-bedded bays in similar wards. Potential routes of transmission were investigated by observational surveys. The relative risk of colonization in five-bedded medium dependency bays was 3.15 compared with that of similar four-bedded bays (P < 0.005), and in five-bedded low dependency bays was 3.16 (P < 0.005). Increasing the number of beds in a fixed area heightens the risk of cross-infection with MRSA.