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Diagnostic Microbiology and Infectious Disease

Melisa M Shah, Eric I Hsiao, Carl M Kirsch, Amit Gohil, Supriya Narasimhan, David A Stevens
Invasive pulmonary aspergillosis (IPA) is classically considered an illness of severely immunocompromised patients with limited host defenses. However, IPA has been reported in immunocompetent but critically ill patients. This report describes two fatal cases of pathologically confirmed IPA in patients with influenza in the intensive care unit. One patient had influenza B infection, whereas the other had influenza A H1N1. Both patients died despite broad-spectrum antimicrobials, mechanical ventilation, and vasopressor support...
February 2, 2018: Diagnostic Microbiology and Infectious Disease
Otto Henrique May Feuerschuette, Sheila Koettker Silveira, Ana Carolina Labor Cancelier, Rosemeri Maurici da Silva, Daisson José Trevisol, Jefferson Ricardo Pereira
Group B Streptococcus is the leading etiologic factor of neonatal sepsis. Intrapartum real-time polymerase chain reaction (RT-PCR) may allow faster and more accurate detection of maternal colonization. The aim of this study was to determine the sensitivity and specificity of RT-PCR when compared to the reference standard culture in selective broth media collected from rectovaginal tract from laboring women. We selected 15 studies that included 6368 women. Papers selection, data extraction, and quality assessment were carried out by two independent researchers...
February 2, 2018: Diagnostic Microbiology and Infectious Disease
Paul M Luethy, Adrian M Zelazny
Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) has revolutionized fungal identification. Previously, we developed a MALDI-TOF MS mold extraction procedure and comprehensive database. While MALDI-TOF MS has become routine in a few laboratories, it has not yet become widespread. A major obstacle is the lack of a simple, reproducible and uniform protein extraction procedure. In this study, we developed and validated a rapid one-step protein extraction protocol for filamentous fungi...
February 2, 2018: Diagnostic Microbiology and Infectious Disease
Kimberly C Claeys, Emily L Heil, Jason M Pogue, Paul R Lephart, J Kristie Johnson
Verigene Blood-Culture Gram-Negative (GN) results in rapid identification of key GNs in bloodstream infections. Its use clinically is limited by low sensitivity in polymicrobial GN infections and concerns for inappropriate antibiotic modification. In a retrospective review of 1003 blood culture sets, the incidence of missed GNs was infrequent, <4%, with the potential to negatively impact the management of GN BSIs in <2% of cases.
February 2, 2018: Diagnostic Microbiology and Infectious Disease
Dixie Huntley, Anna Mollar, Javier Buesa, Silvia Rodríguez, Estela Giménez, Juan Sanchis, Julio Núñez, David Navarro
It has been reported that patients with chronic heart failure exhibit an intestinal overgrowth of primary gut bacterial pathogens, such as Shigella spp., Salmonella spp., Campylobacter spp., and Yersinia enterocolitica. We failed to reproduce these findings in a cohort of 39 patients admitted to the hospital with decompensated heart failure by means of conventional stool bacterial cultures and a multiplexed polymerase chain reaction assay.
February 2, 2018: Diagnostic Microbiology and Infectious Disease
James A Karlowsky, Heather J Adam, Tyler Kosowan, Melanie R Baxter, Kim A Nichol, Nancy M Laing, George Golding, George G Zhanel
Clostridium difficile toxin-positive diarrheal stool specimens submitted to eight Canadian hospital laboratories from 2013 to 2015 were cultured. Polymerase chain reaction ribotyping of isolates was performed using an internationally standardized, high-resolution capillary gel-based electrophoresis protocol and antimicrobial susceptibility testing conducted by CLSI-defined agar dilution (M11-A8, 2012). Among the 1310 isolates of C. difficile cultured, 141 different ribotypes were identified; the most common ribotypes were 027 (24...
January 31, 2018: Diagnostic Microbiology and Infectious Disease
Gunnar T R Hischebeth, Sascha Gravius, Ernst Molitor, Hendrik Kohlhof, Achim Hoerauf, Caecilia Hilgers, Thomas M Randau
Antibiotic therapy is essential in foreign body associated infections. The treatment regime should aim at high tissue concentrations, high bioavailability, high biofilm penetration and good tolerance. We investigated whether the new cephalosporin ceftobiprole is active against clinical isolates from musculoskeletal foreign body associated infections. One hundred ninety-six staphylococci isolates (coagulase negative staphylococci and Staphylococcus aureus) derived from foreign body associated infections were tested towards susceptibility to ceftobiprole, using a test strip assay and broth microdilution...
January 31, 2018: Diagnostic Microbiology and Infectious Disease
Uthaibhorn Singkham-In, Tanittha Chatsuwan
Carbapenem-resistant Acinetobacter baumannii clinical isolates (n=23) were investigated for carbapenem resistance mechanisms and in vitro activities of carbapenems in combination with amikacin, colistin, or fosfomycin. Major carbapenem resistance mechanism was OXA-23 production. The vast majority of these isolates were OXA-23-producing A. baumannii ST195 and ST542, followed by novel STs, ST1417, and ST1423. The interuption of carO by a novel insertion sequence, ISAba40, was found in two isolates. The combinations of imipenem and fosfomycin, meropenem and amikacin, imipenem and amikacin, and imipenem and colistin were synergistic against carbapenem-resistant A...
January 31, 2018: Diagnostic Microbiology and Infectious Disease
Siddharth Sridhar, Cyril C Y Yip, Jasper F W Chan, Kelvin K W To, Vincent C C Cheng, Kwok-Yung Yuen
The Abbott RealTime HCV Genotype II assay (Abbott-RT-HCV assay) is a real-time PCR based genotyping method for hepatitis C virus (HCV). This study measured the impact of inter-genotypic recombination and probe cross-reactivity on the performance of the Abbott-RT-HCV assay. 517 samples were genotyped using the Abbott-RT-HCV assay over a one-year period, 34 (6.6%) were identified as HCV genotype 1 without further subtype designation raising the possibility of inaccurate genotyping. These samples were subjected to confirmatory sequencing...
January 11, 2018: Diagnostic Microbiology and Infectious Disease
Pierre Delpech, Muna ALeryan, Brian Jones, Curtis Gemmell, Sue Lang
Skin and soft tissue infections (SSTI) are among the most commonly occurring infections and evidence suggests that these are increasing world-wide. The aetiology is diverse, but Staphylococcus aureus predominate and these are often resistant to antimicrobials that were previously effective. Tedizolid is a new oxazolidinone-class antibacterial indicated for the treatment of adults with SSTI caused by Gram-positive pathogens, including S. aureus. The aim of this study was to evaluate the in vitro efficacy of tedizolid in comparison to other clinically used antibacterials against antibiotic sensitive- and resistant-staphylococci, grown in planktonic cultures and as biofilms reflecting the growth of the microorganism during episodes of SSTI...
January 10, 2018: Diagnostic Microbiology and Infectious Disease
Sandra S Richter, James Karichu, Joshua Otiso, Hillary Van Heule, George Keller, Eric Cober, Laura J Rojas, Andrea M Hujer, Kristine M Hujer, Steve Marshall, Frederico Perez, Susan D Rudin, T Nicholas Domitrovic, Keith S Kaye, Robert Salata, David van Duin, Robert A Bonomo
Colistin and polymyxin B MICs were determined for 106 carbapenem-resistant Klebsiella pneumoniae (CR-Kp) isolates using Sensititre Research Use Only GNX2F plates (Thermo Fisher) and compared to CLSI broth macrodilution (BMD) as the reference method. For colistin, EUCAST breakpoints were applied and testing of isolates with very major (VM) errors was repeated in duplicate by both methods to determine a majority result. Essential agreement (MIC ± one dilution) of GNX2F with the reference method was 97.1% for polymyxin B and 92...
January 9, 2018: Diagnostic Microbiology and Infectious Disease
Lidya Chaidir, Jessi Annisa, Sofiati Dian, Ida Parwati, Arlisa Alisjahbana, Feby Purnama, Adri van der Zanden, Ahmad Rizal Ganiem, Reinout van Crevel
We evaluated microbiological diagnosis of tuberculous (TB) meningitis in a referral hospital in Indonesia. Over a ten-year period, we examined cerebrospinal fluid (CSF) samples of 1180 adult meningitis suspects. Sensitivity of different methods was compared, and results were stratified for HIV status, disease severity, and CSF volume. TB meningitis was bacteriologically confirmed in 501 patients. Using clinical diagnosis as reference standard (n = 713), sensitivity of different methods was 12.2% (86/703) for microscopy, 42% (73/174) for Xpert MTB/RIF, 46...
January 9, 2018: Diagnostic Microbiology and Infectious Disease
Evgeny A Idelevich, Uwe Groß, Karsten Becker, Oliver Bader
Gradient diffusion assays Etest and MIC Test Strip for itraconazole, posaconazole and voriconazole as well as isavuconazole (MIC Test Strip) were evaluated for Aspergillus fumigatus against EUCAST broth microdilution. Both assays demonstrated generally good performance; however, posaconazole MIC Test Strip showed low agreement with broth microdilution due to MIC overestimation.
January 9, 2018: Diagnostic Microbiology and Infectious Disease
Yothin Teethaisong, Glyn Hobbs, Ismini Nakouti, Katie Evans, Griangsak Eumkeb
Reliable, simple and rapid methods for laboratory detection of carbapenemases are important for an appropriate antibiotic administration. A nitrocefin disc containing ertapenem for rapid screening of carbapenemase production among Enterobacteriaceae is developed in the present study. A total of 87 molecularly-confirmed Enterobacteriaceae including 31 carbapenemase producers and 56 non-carbapenemase producers, were tested with nitrocefin discs supplemented with and without ertapenem (20 μg/disc). Nitrocefin discs with ertapenem successfully discriminated all 31 carbapenemase and all non-carbapenemase producers within 30 minutes...
January 6, 2018: Diagnostic Microbiology and Infectious Disease
Isabella W Martin, Kim Dionne, Sharon M Deml, Nancy L Wengenack, Nicole M Parrish
We examined categorical agreement between automated mycobacterial susceptibility testing methods (Mycobacterial Growth Indicator Tube [MGIT] 960 System and the VersaTREK Mycobacteria Detection and Susceptibility System) which are based on single critical concentration (CC) "breakpoints" and a commercial microbroth dilution method (Sensititre Mycobacterium tuberculosis MIC Plate [MYCOTB]) which provides an MIC value. Mycobacterium tuberculosis isolates (n=355) were tested against three first-line antimycobacterial agents (ethambutol [EMB], isoniazid [INH], rifampin [RIF]) using the MYCOTB plate and either the MGIT 960 (site 1, n=142) or VersaTREK (site 2, n=213) systems...
January 6, 2018: Diagnostic Microbiology and Infectious Disease
Iain D Page, Caroline Baxter, Christophe Hennequin, Malcolm D Richardson, Erna van Hoeyveld, Albert W van Toorenenbergen, David W Denning
Measurement of Aspergillus-specific IgG is central to the diagnosis of chronic pulmonary aspergillosis (CPA), but manufacturers' guidance on test interpretation is based on unpublished data. We performed the first receiver operating characteristic (ROC) area under the curve (AUC) analysis to identify optimal cut-offs for this test in relation to European controls. Aspergillus-specific IgG levels were measured in sera from British adults with CPA and European healthy controls by ImmunoCAP, Immulite, Serion and Bio-Rad assays...
January 6, 2018: Diagnostic Microbiology and Infectious Disease
Lucyna Holec-Gąsior, Bartłomiej Ferra, Justyna Czechowska, Illia E Serdiuk, Karol Krzymiński
Toxoplasma gondii infection is one of the most common human zoonosis. Laboratory diagnosis of this disease is mainly based on the results of serological methods detecting specific antibodies in the patient's sera. In this study we aimed to evaluate the performance of a chemiluminescence immunoassay (CLIA) based on the use of a novel immunochemical reagent in the form of the conjugate of original acridinium label (AL) attached to secondary antibody (IgG-AL) and SAG2-GRA1-ROP1L chimeric antigen for T. gondii specific antibodies detection...
January 6, 2018: Diagnostic Microbiology and Infectious Disease
Adam J Caulfield, Catherine M Bolster LaSalle, Yu-Hui H Chang, Thomas E Grys
Detection of Clostridium difficile infection is important for clinical laboratories, owing to debilitating disease, severe outcomes, patient awareness, and public reporting of hospital data. This study evaluated the performance of 4 nucleic acid amplification test (NAAT) assays as part of a 2-step algorithm that involves reflexive NAAT following enzyme immunoassay (EIA) testing that is indeterminate for glutamate dehydrogenase (GDH) antigen and toxin A/B (GDH+/toxin- or GDH-/toxin+). A total of 500 stool specimens from consecutive patients were tested by each of the 5 methods and also evaluated as part of a 2-step algorithm...
January 3, 2018: Diagnostic Microbiology and Infectious Disease
M A Pfaller, R K Flamm, L R Duncan, J M Streit, M Castanheira, H S Sader
Susceptibility testing of ceftobiprole and comparators against 12,240 isolates was performed following CLSI/EUCAST guidelines. The percentage of susceptible MRSA isolates was higher for ceftobiprole (96.5% susceptible) than for ceftaroline (86.2% susceptible). Both ceftobiprole (MIC50/90, 0.5/2 mg/L) and ceftaroline (MIC50/90, 0.25/1 mg/L) demonstrated potent activity against coagulase-negative staphylococci. Ceftobiprole demonstrated good potency against Enterococcus faecalis (MIC50/90 values of 0.5/2 mg/L); ceftaroline (MIC50/90, 2/8 mg/L) was 4-fold less active against these strains...
January 3, 2018: Diagnostic Microbiology and Infectious Disease
Phillip J Bergen, Jürgen B Bulitta, Fekade B Sime, Jeffrey Lipman, Megan J McGregor, Nada Millen, David L Paterson, Carl M J Kirkpatrick, Jason A Roberts, Cornelia B Landersdorfer
We described bacterial killing and resistance emergence at various fixed concentrations of meropenem and piperacillin/tazobactam against Pseudomonas aeruginosa and Escherichia coli. Time-kill studies were conducted utilizing nine isolates and a large range of concentrations. Within each strain and antibiotic, initial killing was similar, with concentrations ≥2×MIC. At many (strain-specific) concentrations causing substantial initial killing, regrowth occurred at 24-48h. For remaining concentrations, growth typically remained suppressed (<5-log10 cfu/mL)...
January 3, 2018: Diagnostic Microbiology and Infectious Disease
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