Antimicrobial susceptibility and synergy studies of cystic fibrosis sputum by direct sputum sensitivity testing

Serisier, D.J., Tuck, A., Matley, D., Carroll, M.P. and Jones, G. (2012) Antimicrobial susceptibility and synergy studies of cystic fibrosis sputum by direct sputum sensitivity testing. European Journal of Clinical Microbiology and Infectious Diseases, 31 11: 3211-3216.


Author Serisier, D.J.
Tuck, A.
Matley, D.
Carroll, M.P.
Jones, G.
Title Antimicrobial susceptibility and synergy studies of cystic fibrosis sputum by direct sputum sensitivity testing
Journal name European Journal of Clinical Microbiology and Infectious Diseases  (ERA 2012 Listed)    (ERA 2010 Rank B)   Check publisher's open access policy
Publication date 2012
Sub-type Article
DOI 10.1007/s10096-012-1687-6
Volume number 31
Issue number 11
ISSN 0934-9723;1435-4373
Start page 3211
End page 3216
Total pages 6
Place of publication Heidelberg, Germany
Publisher Springer
Collection year 2013
Language eng
Abstract Standard disc diffusion antimicrobial susceptibility testing (C+S) on individual Pseudomonas aeruginosa colonial morphotypes cultured from cystic fibrosis (CF) sputum has questionable clinical relevance. Direct sputum sensitivity testing (DSST) is a whole-sputum susceptibility test that removes bias associated with selecting individual colonial morphotypes. We sought to determine whether, in principle, the results from DSST support the possibility of improved clinical relevance compared with C+S. Individual (DSSTi) and combination (DSST) susceptibility to gentamicin, tobramycin, ceftazidime and meropenem were determined on 130 sputum samples referred from CF subjects with antibiotic-resistant chronic Gram-negative endobronchial infection. DSSTi and concurrent C+S were compared for categorical susceptibility, synergistic combinations were evaluated and the combination DSST efficacy index (DEI) calculated. Meropenem and tobramycin were the most active individual antibiotics by DSSTi on 89 P. aeruginosa-predominant samples, with 62 % of samples sensitive to each. C+S and DSSTi showed poor agreement (κ ranging from 0.02 to 0.6), discordance ranging from 20 % (meropenem) to 49 % (tobramycin), with DSSTi demonstrating both increased susceptibility and increased resistance. The combination that most frequently had the highest DEI was tobramycin + meropenem, occurring in 76 % of samples. DSSTi appears to be reproducible, yields different antimicrobial susceptibility results from C+S without simply identifying the most resistant isolates and DSST identifies the most effective in vitro antibiotic combinations, providing preliminary proof of concept of the potentially improved clinical relevance of whole-sputum testing. Future studies will determine whether these potential theoretical advantages translate into clinical benefits
Keyword Pseudomonas-aeruginosa
Antibiotic combinations
Infective exacerbation
Airway infection
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article
Collections: Official 2013 Collection
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Created: Mon, 30 Jul 2012, 14:08:32 EST by Matthew Lamb on behalf of School of Medicine