John Turnidge
University of Adelaide
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by John Turnidge.
Antimicrobial Agents and Chemotherapy | 2012
Ana Espinel-Ingroff; A.I. Aller; Emilia Cantón; L.R. Castanon-Olivares; Anuradha Chowdhary; S. Cordoba; Manuel Cuenca-Estrella; A. W. Fothergill; J. Fuller; Nelesh P. Govender; Ferry Hagen; M.T. Illnait-Zaragozi; E. Johnson; Sarah Kidd; Cornelia Lass-Flörl; Shawn R. Lockhart; Marilena dos Anjos Martins; Jacques F. Meis; M.S. Melhem; Luis Ostrosky-Zeichner; Teresa Peláez; M. A. Pfaller; Wiley A. Schell; G. St-Germain; Luciana Trilles; John Turnidge
ABSTRACT Epidemiological cutoff values (ECVs) for the Cryptococcus neoformans-Cryptococcus gattii species complex versus fluconazole, itraconazole, posaconazole, and voriconazole are not available. We established ECVs for these species and agents based on wild-type (WT) MIC distributions. A total of 2,985 to 5,733 CLSI MICs for C. neoformans (including isolates of molecular type VNI [MICs for 759 to 1,137 isolates] and VNII, VNIII, and VNIV [MICs for 24 to 57 isolates]) and 705 to 975 MICs for C. gattii (including 42 to 260 for VGI, VGII, VGIII, and VGIV isolates) were gathered in 15 to 24 laboratories (Europe, United States, Argentina, Australia, Brazil, Canada, Cuba, India, Mexico, and South Africa) and were aggregated for analysis. Additionally, 220 to 359 MICs measured using CLSI yeast nitrogen base (YNB) medium instead of CLSI RPMI medium for C. neoformans were evaluated. CLSI RPMI medium ECVs for distributions originating from at least three laboratories, which included ≥95% of the modeled WT population, were as follows: fluconazole, 8 μg/ml (VNI, C. gattii nontyped, VGI, VGIIa, and VGIII), 16 μg/ml (C. neoformans nontyped, VNIII, and VGIV), and 32 μg/ml (VGII); itraconazole, 0.25 μg/ml (VNI), 0.5 μg/ml (C. neoformans and C. gattii nontyped and VGI to VGIII), and 1 μg/ml (VGIV); posaconazole, 0.25 μg/ml (C. neoformans nontyped and VNI) and 0.5 μg/ml (C. gattii nontyped and VGI); and voriconazole, 0.12 μg/ml (VNIV), 0.25 μg/ml (C. neoformans and C. gattii nontyped, VNI, VNIII, VGII, and VGIIa,), and 0.5 μg/ml (VGI). The number of laboratories contributing data for other molecular types was too low to ascertain that the differences were due to factors other than assay variation. In the absence of clinical breakpoints, our ECVs may aid in the detection of isolates with acquired resistance mechanisms and should be listed in the revised CLSI M27-A3 and CLSI M27-S3 documents.
Lancet Infectious Diseases | 2015
Roger L. Nation; Jian Li; Otto Cars; William Couet; Michael N. Dudley; Keith S. Kaye; Johan W. Mouton; David L. Paterson; Vincent H. Tam; Ursula Theuretzbacher; Brian T. Tsuji; John Turnidge
In the face of diminishing therapeutic options for the treatment of infections caused by multidrug-resistant, Gram-negative bacteria, clinicians are increasingly using colistin and polymyxin B. These antibiotics became available clinically in the 1950s, when understanding of antimicrobial pharmacology and regulatory requirements for approval of drugs was substantially less than today. At the 1st International Conference on Polymyxins in Prato, Italy, 2013, participants discussed a set of key objectives that were developed to explore the factors affecting the safe and effective use of polymyxins, identify the gaps in knowledge, and set priorities for future research. Participants identified several factors that affect the optimum use of polymyxins, including: confusion caused by several different conventions used to describe doses of colistin; an absence of appropriate pharmacopoeial standards for polymyxins; outdated and diverse product information; and uncertainties about susceptibility testing and breakpoints. High-priority areas for research included: better definition of the effectiveness of polymyxin-based combination therapy compared with monotherapy via well designed, randomised controlled trials; examination of the relative merits of colistin versus polymyxin B for various types of infection; investigation of pharmacokinetics in special patient populations; and definition of the role of nebulised polymyxins alone or in combination with intravenous polymyxins for the treatment of pneumonia. The key areas identified provide a roadmap for action regarding the continued use of polymyxins, and are intended to help with the effective and safe use of these important, last-line antibiotics.
Veterinary Medicine International | 2011
J. Scott Weese; Joseph M. Blondeau; Dawn M. Boothe; Edward B. Breitschwerdt; Luca Guardabassi; Andrew Hillier; David Lloyd; Mark G. Papich; Shelley C. Rankin; John Turnidge; Jane E. Sykes
Urinary tract disease is a common reason for use (and likely misuse, improper use, and overuse) of antimicrobials in dogs and cats. There is a lack of comprehensive treatment guidelines such as those that are available for human medicine. Accordingly, guidelines for diagnosis and management of urinary tract infections were created by a Working Group of the International Society for Companion Animal Infectious Diseases. While objective data are currently limited, these guidelines provide information to assist in the diagnosis and management of upper and lower urinary tract infections in dogs and cats.
Antimicrobial Agents and Chemotherapy | 2013
Ana Espinel-Ingroff; Maiken Cavling Arendrup; M. A. Pfaller; L.X. Bonfietti; Beatriz Bustamante; Emilia Cantón; Erja Chryssanthou; Manuel Cuenca-Estrella; Eric Dannaoui; A. W. Fothergill; J. Fuller; Peter Gaustad; Gloria M. González; Josep Guarro; Cornelia Lass-Flörl; Shawn R. Lockhart; Jacques F. Meis; Caroline B. Moore; Luis Ostrosky-Zeichner; Teresa Peláez; S. R B S Pukinskas; G. St-Germain; M. W. Szeszs; John Turnidge
ABSTRACT Although Clinical and Laboratory Standards Institute (CLSI) clinical breakpoints (CBPs) are available for interpreting echinocandin MICs for Candida spp., epidemiologic cutoff values (ECVs) based on collective MIC data from multiple laboratories have not been defined. While collating CLSI caspofungin MICs for 145 to 11,550 Candida isolates from 17 laboratories (Brazil, Canada, Europe, Mexico, Peru, and the United States), we observed an extraordinary amount of modal variability (wide ranges) among laboratories as well as truncated and bimodal MIC distributions. The species-specific modes across different laboratories ranged from 0.016 to 0.5 μg/ml for C. albicans and C. tropicalis, 0.031 to 0.5 μg/ml for C. glabrata, and 0.063 to 1 μg/ml for C. krusei. Variability was also similar among MIC distributions for C. dubliniensis and C. lusitaniae. The exceptions were C. parapsilosis and C. guilliermondii MIC distributions, where most modes were within one 2-fold dilution of each other. These findings were consistent with available data from the European Committee on Antimicrobial Susceptibility Testing (EUCAST) (403 to 2,556 MICs) for C. albicans, C. glabrata, C. krusei, and C. tropicalis. Although many factors (caspofungin powder source, stock solution solvent, powder storage time length and temperature, and MIC determination testing parameters) were examined as a potential cause of such unprecedented variability, a single specific cause was not identified. Therefore, it seems highly likely that the use of the CLSI species-specific caspofungin CBPs could lead to reporting an excessive number of wild-type (WT) isolates (e.g., C. glabrata and C. krusei) as either non-WT or resistant isolates. Until this problem is resolved, routine testing or reporting of CLSI caspofungin MICs for Candida is not recommended; micafungin or anidulafungin data could be used instead.
Antimicrobial Agents and Chemotherapy | 2011
Ana Espinel-Ingroff; Manuel Cuenca-Estrella; A. W. Fothergill; J. Fuller; Mahmoud A. Ghannoum; E. Johnson; Teresa Peláez; M. A. Pfaller; John Turnidge
ABSTRACT Although clinical breakpoints have not been established for mold testing, epidemiological cutoff values (ECVs) are available for Aspergillus spp. versus the triazoles and caspofungin. Wild-type (WT) MIC distributions (organisms in a species-drug combination with no acquired resistance mechanisms) were defined in order to establish ECVs for six Aspergillus spp. and amphotericin B. Two sets (CLSI/EUCAST broth microdilution) of available MICs were evaluated: those for A. fumigatus (3,988/833), A. flavus (793/194), A. nidulans (184/69), A. niger (673/140), A. terreus (545/266), and A. versicolor (135/22). Three sets of data were analyzed: (i) CLSI data gathered in eight independent laboratories in Canada, Europe, and the United States; (ii) EUCAST data from a single laboratory; and (iii) the combined CLSI and EUCAST data. ECVs, expressed in μg/ml, that captured 95%, 97.5%, and 99% of the modeled wild-type population (CLSI and combined data) were as follows: for A. fumigatus, 2, 2, and 4; for A. flavus, 2, 4, and 4; for A. nidulans, 4, 4, and 4; for A. niger, 2, 2, and 2; for A. terreus, 4, 4, and 8; and for A. versicolor, 2, 2, and 2. Similar to the case for the triazoles and caspofungin, amphotericin B ECVs may aid in the detection of strains with acquired mechanisms of resistance to this agent.
Antimicrobial Agents and Chemotherapy | 2014
Ana Espinel-Ingroff; M. A. Pfaller; Beatriz Bustamante; Emilia Cantón; A. W. Fothergill; J. Fuller; Gloria M. González; Cornelia Lass-Flörl; Shawn R. Lockhart; Estrella Martín-Mazuelos; Jacques F. Meis; M.S. Melhem; Luis Ostrosky-Zeichner; Teresa Peláez; M. W. Szeszs; G. St-Germain; L.X. Bonfietti; Josep Guarro; John Turnidge
ABSTRACT Although epidemiological cutoff values (ECVs) have been established for Candida spp. and the triazoles, they are based on MIC data from a single laboratory. We have established ECVs for eight Candida species and fluconazole, posaconazole, and voriconazole based on wild-type (WT) MIC distributions for isolates of C. albicans (n = 11,241 isolates), C. glabrata (7,538), C. parapsilosis (6,023), C. tropicalis (3,748), C. krusei (1,073), C. lusitaniae (574), C. guilliermondii (373), and C. dubliniensis (162). The 24-h CLSI broth microdilution MICs were collated from multiple laboratories (in Canada, Brazil, Europe, Mexico, Peru, and the United States). The ECVs for distributions originating from ≥6 laboratories, which included ≥95% of the modeled WT population, for fluconazole, posaconazole, and voriconazole were, respectively, 0.5, 0.06 and 0.03 μg/ml for C. albicans, 0.5, 0.25, and 0.03 μg/ml for C. dubliniensis, 8, 1, and 0.25 μg/ml for C. glabrata, 8, 0.5, and 0.12 μg/ml for C. guilliermondii, 32, 0.5, and 0.25 μg/ml for C. krusei, 1, 0.06, and 0.06 μg/ml for C. lusitaniae, 1, 0.25, and 0.03 μg/ml for C. parapsilosis, and 1, 0.12, and 0.06 μg/ml for C. tropicalis. The low number of MICs (<100) for other less prevalent species (C. famata, C. kefyr, C. orthopsilosis, C. rugosa) precluded ECV definition, but their MIC distributions are documented. Evaluation of our ECVs for some species/agent combinations using published individual MICs for 136 isolates (harboring mutations in or upregulation of ERG11, MDR1, CDR1, or CDR2) and 64 WT isolates indicated that our ECVs may be useful in distinguishing WT from non-WT isolates.
Clinical Infectious Diseases | 2012
Céline Pulcini; Karen Bush; William A. Craig; Niels Frimodt-Møller; M. Lindsay Grayson; Johan W. Mouton; John Turnidge; Stéphan Juergen Harbarth; Inge C. Gyssens
In view of the alarming spread of antimicrobial resistance in the absence of new antibiotics, this study aimed at assessing the availability of potentially useful older antibiotics. A survey was performed in 38 countries among experts including hospital pharmacists, microbiologists, and infectious disease specialists in Europe, the United States, Canada, and Australia. An international expert panel selected systemic antibacterial drugs for their potential to treat infections caused by resistant bacteria or their unique value for specific criteria. Twenty-two of the 33 selected antibiotics were available in fewer than 20 of 38 countries. Economic motives were the major cause for discontinuation of marketing of these antibiotics. Fourteen of 33 antibiotics are potentially active against either resistant Gram-positive or Gram-negative bacteria. Urgent measures are then needed to ensure better availability of these antibiotics on a global scale.
Antimicrobial Agents and Chemotherapy | 2011
Ching-Lan Lu; Chia-Ying Liu; Yu-Tsung Huang; Chun-Hsing Liao; Lee-Jene Teng; John Turnidge; Po-Ren Hsueh
ABSTRACT We studied the antimicrobial activity of fosfomycin against 960 strains of commonly encountered bacteria associated with urinary tract infection using standard agar dilution and disk diffusion methods. Species studied included 3 common species of Enterobacteriaceae, Pseudomonas aeruginosa, Acinetobacter baumannii, and Stenotrophomonas maltophilia; methicillin-susceptible and -resistant Staphylococcus aureus; and vancomycin-susceptible and resistant Enterococcus faecalis and E. faecium. MICs and inhibition zone diameters were interpreted in accordance with both the currently recommended Clinical and Laboratory Standards Institute (CLSI) criteria for urinary tract isolates of Escherichia coli and Enterococcus faecalis and the European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria for Enterobacteriaceae. Tentative zone diameter interpretive criteria were developed for species not currently published by CLSI or EUCAST. Escherichia coli was uniformly susceptible to fosfomycin, as were most strains of Klebsiella pneumoniae and Enterobacter cloacae. A. baumannii was resistant to fosfomycin, while the prevalence of resistance in P. aeruginosa and S. maltophilia was greatly affected by the choice of MIC breakpoint. New tentative zone diameter criteria for K. pneumoniae, E. cloacae, S. aureus, and E. faecium were able to be set, providing some interim laboratory guidance for disk diffusion until further breakpoint evaluations are undertaken by CLSI and EUCAST.
Journal of Antimicrobial Chemotherapy | 2015
Soon-Ee Cheah; Jiping Wang; Van Thi Thu Nguyen; John Turnidge; Jian Li; Roger L. Nation
OBJECTIVESnThis study investigated the exposure-response relationships between unbound colistin in plasma and antibacterial activity in mouse thigh and lung infections.nnnMETHODSnDose fractionation studies (subcutaneous colistin sulphate at 1.25-160 mg/kg/day) were conducted in neutropenic mice in which infection (three strains of Pseudomonas aeruginosa and three strains of Acinetobacter baumannii) had been produced by intramuscular thigh injection or aerosol lung delivery. Bacterial burden was measured at 24 h after initiation of colistin treatment. Plasma protein binding was measured by rapid equilibrium dialysis and ultracentrifugation. The inhibitory sigmoid dose-effect model and non-linear least squares regression were employed to determine the relationship between exposure to unbound colistin and efficacy.nnnRESULTSnPlasma binding of colistin was constant over the concentration range ∼2-50 mg/L. The averageu200a±u200aSD percentage bound for all concentrations was 92.9u200a±u200a3.3% by ultracentrifugation and 90.4u200a±u200a1.1% by equilibrium dialysis. In the thigh model, across all six strains the antibacterial effect of colistin was well correlated with fAUC/MIC (R(2)u200a=u200a0.82-0.94 for P. aeruginosa and R(2)u200a=u200a0.84-0.95 for A. baumannii). Target values of fAUC/MIC for 2 log10 kill were 7.4-13.7 for P. aeruginosa and 7.4-17.6 for A. baumannii. In the lung model, for only two strains of P. aeruginosa and one strain of A. baumannii was it possible to achieve 2 log10 kill (fAUC/MIC target values 36.8-105), even at the highest colistin dose tolerated by mice. This dose was not able to achieve bacteriostasis for the other two strains of A. baumannii.nnnCONCLUSIONSnColistin was substantially less effective in lung infection. The pharmacokinetic/pharmacodynamic target values will assist in the design of optimized dosage regimens.
Antimicrobial Agents and Chemotherapy | 2013
Ana Espinel-Ingroff; Anuradha Chowdhary; Gloria M. González; Cornelia Lass-Flörl; Estrella Martín-Mazuelos; Jacques F. Meis; Teresa Peláez; M. A. Pfaller; John Turnidge
ABSTRACT Epidemiological cutoff values (ECVs) were established for the new triazole isavuconazole and Aspergillus species wild-type (WT) MIC distributions (organisms in a species-drug combination with no detectable acquired resistance mechanisms) that were defined with 855 Aspergillus fumigatus, 444 A. flavus, 106 A. nidulans, 207 A. niger, 384 A. terreus, and 75 A. versicolor species complex isolates; 22 Aspergillus section Usti isolates were also included. CLSI broth microdilution MIC data gathered in Europe, India, Mexico, and the United States were aggregated to statistically define ECVs. ECVs were 1 μg/ml for the A. fumigatus species complex, 1 μg/ml for the A. flavus species complex, 0.25 μg/ml for the A. nidulans species complex, 4 μg/ml for the A. niger species complex, 1 μg/ml for the A. terreus species complex, and 1 μg/ml for the A. versicolor species complex; due to the small number of isolates, an ECV was not proposed for Aspergillus section Usti. These ECVs may aid in detecting non-WT isolates with reduced susceptibility to isavuconazole due to cyp51A (an A. fumigatus species complex resistance mechanism among the triazoles) or other mutations.