Mutations in SNF1 complex genes affect yeast cell wall strength.
Eur J Cell Biol. 2014 Jan 10;
Authors: Backhaus K, Rippert D, Heilmann CJ, Sorgo AG, de Koster CG, Klis FM, Rodicio R, Heinisch JJ
The trimeric SNF1 complex from Saccharomyces cerevisiae, a homolog of mammalian AMP-activated kinase, has been primarily implicated in signaling for the utilization of alternative carbon sources to glucose. We here find that snf1 deletion mutants are hypersensitive to different cell wall stresses, such as the presence of Calcofluor white, Congo red, Zymolyase or the glucan synthase inhibitor Caspofungin in the growth medium. They also have a thinner cell wall. Caspofungin treatment triggers the phosphorylation of the catalytic Snf1 kinase subunit at Thr210 and removal of this phosphorylation site by mutagenesis (Snf1-T210A) abolishes the function of Snf1 in cell wall integrity. Deletion of the PFK1 gene encoding the α-subunit of the heterooctameric yeast phosphofructokinase suppresses the cell wall phenotypes of a snf1 deletion, which suggests a compensatory effect of central carbohydrate metabolism. Epistasis analyses with mutants in cell wall integrity (CWI) signaling confirm that the SNF1 complex and the CWI pathway independently affect yeast cell integrity.
PMID: 24486034 [PubMed – as supplied by publisher]
ESCMID/ECMM Joint Clinical Guidelines for the Diagnosis and Management of Systemic Phaeohyphomycosis: Diseases Caused by Black Fungi.
Clin Microbiol Infect. 2014 Jan 31;
Authors: Chowdhary A, Meis JF, Guarro J, de Hoog GS, Kathuria S, Arendrup MC, Arikan-Akdagli S, Akova M, Boekhout T, Caira M, Guinea J, Chakrabarti A, Dannaoui E, van Diepeningen A, Freiberger T, Groll AH, Hope WW, Johnson E, Lackner M, Lagrou K, Lanternier F, Lass-Flörl C, Lortholary O, Meletiadis J, Muñoz P, Pagano L, Petrikkos G, Richardson MD, Roilides E, Skiada A, Tortorano AM, Ullmann AJ, Verweij PE, Cornely OA, Cuenca-Estrella M
The etiologic agents of many invasive fungal infections are saprobes and opportunistic pathogens. Some of these fungi are darkly pigmented due to melanin production and traditionally have been named ‘dematiaceous’. The melanised fungi cause a wide array of clinical syndromes ranging from superficial to deep-seated infections. Diagnosis relies on histopathological examination of clinical specimens and of examination of cultures. Sequencing is recommended for accurate species identification, especially for unusual or newly described pathogens. In cases of mycetoma and chromoblastomycosis, pathognomonic histological findings are very useful and the Fontana-Masson stain, specific for melanin, usually confirms the diagnosis. There are no standardized therapies but voriconazole, posaconazole and itraconazole demonstrate the most consistent in vitro activity against this group of fungi. Oral itraconazole has been considered the drug of choice, given the extensive clinical experience with this drug. However, voriconazole may presumably be superior for central nervous system infections due to its ability to achieve good cerebrospinal fluid levels. Posaconazole is a well-tolerated alternative drug, backed by less clinical experience but with excellent salvage treatment results after failure of other antifungals. Amphotericin B has been useful as alternative therapy in some cases. Combination antifungal therapy is recommended for cerebral abscesses when surgery is not possible and for disseminated infections in immunocompromised patients. This article is protected by copyright. All rights reserved.
PMID: 24483780 [PubMed – as supplied by publisher]
Detection of carbapenemase activities of Bacteroides fragilis strains with Matrix-assisted laser desorption ionization -Time of flight Mass spectrometry (MALDI-TOF MS).
Anaerobe. 2014 Jan 27;
Authors: Johansson A, Nagy E, Sóki J, ESGAI (ESCMID Study Group on Anaerobic Infections)
Today resistance against carbapenems is considered an emerging problem in Bacteroides fragilis. Carbapenemase activities produced by aerobic bacteria have been detected by looking at hydrolysis of carbapenems with MALDI-TOF MS, but this technique was never used for anaerobic bacteria. We have developed a protocol for detection and verification of carbapenemase production in B. fragilis within 2.5 hours. Twenty-eight strains of B. fragilis were tested. Of the sixteen cfiA-positive strains all showed hydrolysis of ertapenem, whereas the twelve cfiA-negative strains showed no hydrolysis. Ertapenem hydrolysis could be inhibited with 2,6-Pyridinecarboxylic acid (DPA) in all cfiA-positive strains, verifying the presence of the metallo-beta-lactamase. Here we show a rapid way to detect carbapenemase activities of B. fragilis strains.
PMID: 24480431 [PubMed – as supplied by publisher]
ESCMID and ECMM Joint Clinical Guidelines for the Diagnosis and Management of Mucormycosis 2013.
Clin Microbiol Infect. 2014 Jan 30;
Authors: Cornely OA, Arikan-Akdagli S, Dannaoui E, Groll AH, Lagrou K, Chakrabarti A, Lanternier F, Pagano L, Skiada A, Akova M, Arendrup MC, Boekhout T, Chowdhary A, Cuenca-Estrella M, Freiberger T, Guinea J, Guarro J, de Hoog S, Hope W, Johnson E, Kathuria S, Lackner M, Lass-Flörl C, Lortholary O, Meis JF, Meletiadis J, Muñoz P, Richardson M, Roilides E, Tortorano AM, Ullmann AJ, van Diepeningen A, Verweij P, Petrikkos G
This ESCMID and ECMM Joint Clinical Guidelines focus on the diagnosis and management of mucormycosis. Only a few of the numerous recommendations can be summarised here. To diagnose mucormycosis, direct microscopy preferably using optical brighteners, histopathology and culture are strongly recommended. Pathogen identification to species level by molecular methods and susceptibility testing are strongly recommended to establish epidemiological knowledge. The recommendation for guiding treatment based on minimal inhibitory concentrations is supported only marginally. Imaging is strongly recommended to determine the extent of disease. To differentiate mucormycosis from aspergillosis in haematological malignancy and stem cell transplantation recipients, identification of the reversed halo sign on computed tomography is advised with moderate strength. For adults and children we strongly recommend surgical debridement in addition to immediate first-line antifungal treatment with liposomal or lipid-complex amphotericin B with a minimum dose of 5 mg/kg/d. Amphotericin B deoxycholate is better avoided due to severe side effects. For salvage treatment we strongly recommend posaconazole 4×200 mg/d. Reversal of predisposing conditions is strongly recommended, i.e. using granulocyte colony stimulating factor in haematologic patients with ongoing neutropaenia, controlling hyperglycaemia and ketoacidosis in diabetic patients, and limiting glucocorticosteroids to the minimum dose required. We recommend against using deferasirox in haematological patients outside of clinical trials, and marginally support a recommendation for deferasirox in diabetic patients. Hyperbaric oxygen is supported with marginal strength only. Finally, we strongly recommend continuing treatment until complete response demonstrated on imaging and permanent reversal of predisposing factors. This article is protected by copyright. All rights reserved.
PMID: 24479848 [PubMed – as supplied by publisher]
Micafungin For The Treatment Of Invasive Aspergillosis.
J Infect. 2014 Jan 27;
Authors: Enoch DA, Idris SF, Aliyu SH, Micallef C, Sule O, Karas JA
Invasive aspergillosis is a major ca…
Transient neutropenia in children with febrile illness and associated infectious agents: 2 years’ follow-up.
Eur J Pediatr. 2013 Jun;172(6):811-9
Authors: Alexandropoulou O, Kossiva L, Haliotis F, Giannaki M, Tsolia M, Panagiotou IP, Karavanaki K
The aim of the study was to identify the relationship of acquired neutropenia with childhood infections and to assess its clinical course, complications, and outcome. Children admitted to two pediatric wards over a 4-year period with febrile neutropenia were prospectively investigated for underlying infections with inflammatory markers, cultures of body fluids, and serological tests. The study included 161 previously healthy children with febrile neutropenia/leukopenia aged (mean ± SD) 3.02 ± 3.86 years (range, 0.1-14). One hundred and thirty-six out of 161 patients (84.5 %) had transient neutropenia (TN), while in 25 patients, neutropenia was chronic (CN) and persisted for ≥180 days. An infectious agent was isolated in 98/161 (60.9 %) cases, in 68.4 % patients with TN, and in 20 % of those with CN (p = 0.001). Among the patients with CN, seven had positive antineutrophil antibodies (autoimmune neutropenia) and four were eventually diagnosed with hematological malignancy. In all age groups, TN was of short duration (<1 month), of mild to moderate severity, and was predominantly associated with viral infections. Two years after diagnosis, 143/161 children (88.8 %) were available for follow-up. One hundred and thirty-seven of 143 (95.8 %) had recovered completely, while the rest remained neutropenic. The latter patients had a benign course despite severe neutropenia. In conclusion, febrile neutropenia during childhood is usually transient, often following viral and common bacterial infections, without serious complications and in the majority of cases it resolves spontaneously. However, in a considerable percentage of patients, neutropenia is discovered incidentally during the course of an infection on the ground of an underlying hematological disease.
PMID: 23408310 [PubMed – indexed for MEDLINE]
Performance of serum biomarkers for the early detection of invasive aspergillosis in febrile, neutropenic patients: a multi-state model.
PLoS One. 2013;8(6):e65776
Authors: Schwarzinger M, Sagaon-Teyssier L, Cabaret O, Bretagne S, Cordonnier C, PREVERT Investigators
BACKGROUND: The performance of serum biomarkers for the early detection of invasive aspergillosis expectedly depends on the timing of test results relative to the empirical administration of antifungal therapy during neutropenia, although a dynamic evaluation framework is lacking.
METHODS: We developed a multi-state model describing simultaneously the likelihood of empirical antifungal therapy and the risk of invasive aspergillosis during neutropenia. We evaluated whether the first positive test result with a biomarker is an independent predictor of invasive aspergillosis when both diagnostic information used to treat and risk factors of developing invasive aspergillosis are taken into account over time. We applied the multi-state model to a homogeneous cohort of 185 high-risk patients with acute myeloid leukemia. Patients were prospectively screened for galactomannan antigenemia twice a week for immediate treatment decision; 2,214 serum samples were collected on the same days and blindly assessed for (1->3)- β-D-glucan antigenemia and a quantitative PCR assay targeting a mitochondrial locus.
RESULTS: The usual evaluation framework of biomarker performance was unable to distinguish clinical benefits of β-glucan or PCR assays. The multi-state model evidenced that the risk of invasive aspergillosis is a complex time function of neutropenia duration and risk management. The quantitative PCR assay accelerated the early detection of invasive aspergillosis (P = .010), independently of other diagnostic information used to treat, while β-glucan assay did not (P = .53).
CONCLUSIONS: The performance of serum biomarkers for the early detection of invasive aspergillosis is better apprehended by the evaluation of time-varying predictors in a multi-state model. Our results provide strong rationale for prospective studies testing a preemptive antifungal therapy, guided by clinical, radiological, and bi-weekly blood screening with galactomannan antigenemia and a standardized quantitative PCR assay.
PMID: 23799048 [PubMed – indexed for MEDLINE]
Aspergillus felis sp. nov., an emerging agent of invasive aspergillosis in humans, cats, and dogs.
PLoS One. 2013;8(6):e64871
Authors: Barrs VR, van Doorn TM, Houbraken J, Kidd SE, Martin P, Pinheiro MD, Richardson M, Varga J, Samson RA
We describe a novel heterothallic species in Aspergillus section Fumigati, namely A. felis (neosartorya-morph) isolated from three host species with invasive aspergillosis including a human patient with chronic invasive pulmonary aspergillosis, domestic cats with invasive fungal rhinosinusitis and a dog with disseminated invasive aspergillosis. Disease in all host species was often refractory to aggressive antifungal therapeutic regimens. Four other human isolates previously reported as A. viridinutans were identified as A. felis on comparative sequence analysis of the partial β-tubulin and/or calmodulin genes. A. felis is a heterothallic mold with a fully functioning reproductive cycle, as confirmed by mating-type analysis, induction of teleomorphs within 7 to 10 days in vitro and ascospore germination. Phenotypic analyses show that A. felis can be distinguished from the related species A. viridinutans by its ability to grow at 45°C and from A. fumigatus by its inability to grow at 50°C. Itraconazole and voriconazole cross-resistance was common in vitro.
PMID: 23798996 [PubMed – indexed for MEDLINE]
USE OF THE PARENTERAL ANTIBIOTIC ERTAPENEM AS SHORT TERM PROPHYLAXIS IN BARIATRIC SURGERY: A PHARMACOKINETICPHARMACODYNAMIC STUDY IN CLASS III OBESE FEMALE PATIENTS.
Minerva Anestesiol. 2014 Jan 30;
Authors: Borracci T, Adembri C, Accetta G, Berti J, Cappellini I, Lucchese M, Biggeri A, De Gaudio AR, Novelli A
Objectives: The objective of this study was to determine the pharmacokineticspharmacodynamics (PK/PD) of Ertapenem in extremely obese female patients (body mass index [BMI] 40 kg/m2) undergoing bariatric surgery. Methods: Ten patients received 1g intravenous Ertapenem 0.5h prior to surgery as short term prophylaxis. Serum Ertapenem concentrations were determined at baseline, at the end of infusion (30 minutes), then at 1,2, 4, 8, 12 and 24 hours postinfusion. In patients in whom a liver biopsy was necessitated by clinical need, Ertapenem liver concentrations were determined through intraoperative biopsies at 1 and 2 h postadministration. Peritoneal Ertapenem concentrations were determined in drainage fluid samples collected during the 48, 812, and 1224 h intervals after Ertapenem administration. A Monte Carlo simulation was performed to estimate the probability of achieving free drug levels above the minimum inhibitory concentration (fT>MIC ) for at least 20% and 40% of the dosing interval as PK/PD targets. Results: Peak drug concentration and 24h area under the concentrationtime curve (AUC) were found to be 191.9±37.4mg/L and 574.3+110.5mg∙h/L, respectively. Ertapenem liver/serum concentration ratios were 6% at 1 h and 5% at 2 h. Drug concentrations in peritoneal fluid were 28.2+6,4 mg/L at 48h, declined to 15.2 + 5.9 at 812h and fell further to 4.79+0.2 mg/L at 1224 h postadministration. The probability to reach the desired PK/PD targets were never reached at any MICs >0.25 μg/ml with a 90% probability. Conclusions: Our data suggest that in extremely obese female patients, the standard dose of 1 g i.v. Ertapenem as short term prophylaxis may not provide optimal clinical levels of free drug for prevention of surgical site infections.
PMID: 24476845 [PubMed – as supplied by publisher]
Evaluation of The Clinical and Laboratory Standards Institute (CLSI) Phenotypic Confirmatory Test to Detect the Presence of Extended-Spectrum Beta-lactamases (ESBL) from 4,005 Escherichia coli, Klebsiella oxytoca, Klebsiella pneumonia and Proteus mirabilis.
J Med Microbiol. 2014 Jan 29;
Authors: Morrissey I, Bouchillon SK, Hackel M, Biedenbach DJ, Hawser SP, Hoban D, Badal RE
A sub-set of Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae and Proteus mirabilis collected for the Study for Monitoring Antimicrobial Resistance Trends (SMART) that were positive for the CLSI extended-spectrum beta-lactamase (ESBL) phenotypic confirmatory test (N=3,245) or had an ertapenem MIC of ≥0.5μg/ml (N=293) or both (N=467) were analyzed for ESBL genes. Most ESBL phenotype E. coli or K. pneumoniae possessed an ESBL gene (95.8% & 88.4%, respectively) or 93.1% if carbapenem non-susceptible K. pneumoniae were removed. This rate was lower for P. mirabilis (73.4%) and K. oxytoca (62.5%). Virtually all ESBL-positive isolates (99.5%) were cefotaxime non-susceptible (CLSI or EUCAST breakpoints). Fewer (82%) were ceftazidime non-susceptible (CLSI breakpoints). Also 21.1% of E. coli, 25% of K. oxytoca and 78.7% of P. mirabilis were ceftazidime-susceptible but ESBL-positive. This suggests CLSI breakpoints for ceftazidime are too high to detect ESBLs. The lower EUCAST breakpoints detected ESBLs in E. coli and K. oxytoca better, but 59.6% of ESBL-positive isolates of P. mirabilis were ceftazidime-susceptible. For isolates with ertapenem MIC ≥ 0.5μg/ml, more accurate ESBL phenotype analysis was observed for E. coli and K. pneumoniae (sensitivity >95% for both, specificity 94.4% and 54.1%, respectively). If carbapenemase-positive K. pneumoniae were excluded specificity increased to 78%. The positive predictive values for the ESBL phenotypic test with E. coli and K. pneumoniae were 97.6% and 81.8%, respectively and negative predictive values were 75.9% and 95.2%, respectively. We therefore suggest it would be prudent to confirm phenotypic ESBL-positive P. mirabilis, K. pneumoniae and K. oxytoca with molecular analysis.
PMID: 24478449 [PubMed – as supplied by publisher]