Relative resistance index (RRI) - a scoring system for antibiotic resistance in Pseudomonas aeruginosa

Joanne C. Ewing, J McCaughan, J Moore, D Fairley, B Sutherland, A Reid, D Downey

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Abstract

BACKGROUND

 There is a need to measure antibiotic resistance of Pseudomonas aeruginosa (PA) in cystic fibrosis (CF), either qualitatively or quantitatively, to inform patient management. The aim of this study was to develop a simple method by which resistance can be quantified by calculating a relative resistance index (RRI), and to assess correlation of RRIs with clinical variables.

METHODS

In our model, RRIs were calculated based on resistance to aztreonam, ceftazidime, ciprofloxacin, colistin, meropenem, tazocin, temicillin and tobramycin. Eighty-five adults with CF and chronic PA colonisation were identified. For each, all PA cultures were allocated a score of 0 for susceptible, 0.5 for intermediate resistance or 1 for resistance for each antibiotic listed above, and the RRI calculated by dividing the sum of these by the number of antibiotics, giving a maximum score of 1. The mean RRIs for all cultures were correlated with key clinical variables monitored in CF patients (including age, FEV1, IV antibiotic days and BMI).

RESULTS

 RRIs for non-mucoid PA exhibited moderate positive correlation with total number of IV days (r = 0.405; p < 0.001) and moderate negative correlation with FEV1 % predicted (r = -0.437; p < 0.001). RRIs were not significantly correlated with duration of colonisation, typing (clonal vs other strain) or BMI. Median RRIs were significantly higher for females (0.26, IQR 0.13-0.54) than males (0.18, IQR 0.07-0.37) for non-mucoid PA only (p = 0.03).

CONCLUSIONS

RRI is an easily calculated measure that correlates with other clinical variables in CF patients and enables quantitative monitoring of resistance.

Original languageEnglish
Number of pages5
JournalBritish Journal of Biomedical Science
Early online date26 Jul 2017
DOIs
Publication statusEarly online date - 26 Jul 2017

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Microbial Drug Resistance
Pseudomonas aeruginosa
Cystic Fibrosis
Anti-Bacterial Agents
meropenem
Aztreonam
Colistin
Tobramycin
Ceftazidime
Ciprofloxacin
Monitoring

Keywords

  • Journal Article

Cite this

@article{bc623492f5274cdf93ad70498488748f,
title = "Relative resistance index (RRI) - a scoring system for antibiotic resistance in Pseudomonas aeruginosa",
abstract = "BACKGROUND There is a need to measure antibiotic resistance of Pseudomonas aeruginosa (PA) in cystic fibrosis (CF), either qualitatively or quantitatively, to inform patient management. The aim of this study was to develop a simple method by which resistance can be quantified by calculating a relative resistance index (RRI), and to assess correlation of RRIs with clinical variables.METHODSIn our model, RRIs were calculated based on resistance to aztreonam, ceftazidime, ciprofloxacin, colistin, meropenem, tazocin, temicillin and tobramycin. Eighty-five adults with CF and chronic PA colonisation were identified. For each, all PA cultures were allocated a score of 0 for susceptible, 0.5 for intermediate resistance or 1 for resistance for each antibiotic listed above, and the RRI calculated by dividing the sum of these by the number of antibiotics, giving a maximum score of 1. The mean RRIs for all cultures were correlated with key clinical variables monitored in CF patients (including age, FEV1, IV antibiotic days and BMI).RESULTS RRIs for non-mucoid PA exhibited moderate positive correlation with total number of IV days (r = 0.405; p < 0.001) and moderate negative correlation with FEV1 {\%} predicted (r = -0.437; p < 0.001). RRIs were not significantly correlated with duration of colonisation, typing (clonal vs other strain) or BMI. Median RRIs were significantly higher for females (0.26, IQR 0.13-0.54) than males (0.18, IQR 0.07-0.37) for non-mucoid PA only (p = 0.03).CONCLUSIONSRRI is an easily calculated measure that correlates with other clinical variables in CF patients and enables quantitative monitoring of resistance.",
keywords = "Journal Article",
author = "Ewing, {Joanne C.} and J McCaughan and J Moore and D Fairley and B Sutherland and A Reid and D Downey",
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month = "7",
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Relative resistance index (RRI) - a scoring system for antibiotic resistance in Pseudomonas aeruginosa. / Ewing, Joanne C.; McCaughan, J; Moore, J; Fairley, D; Sutherland, B; Reid, A; Downey, D.

In: British Journal of Biomedical Science, 26.07.2017.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Relative resistance index (RRI) - a scoring system for antibiotic resistance in Pseudomonas aeruginosa

AU - Ewing, Joanne C.

AU - McCaughan, J

AU - Moore, J

AU - Fairley, D

AU - Sutherland, B

AU - Reid, A

AU - Downey, D

PY - 2017/7/26

Y1 - 2017/7/26

N2 - BACKGROUND There is a need to measure antibiotic resistance of Pseudomonas aeruginosa (PA) in cystic fibrosis (CF), either qualitatively or quantitatively, to inform patient management. The aim of this study was to develop a simple method by which resistance can be quantified by calculating a relative resistance index (RRI), and to assess correlation of RRIs with clinical variables.METHODSIn our model, RRIs were calculated based on resistance to aztreonam, ceftazidime, ciprofloxacin, colistin, meropenem, tazocin, temicillin and tobramycin. Eighty-five adults with CF and chronic PA colonisation were identified. For each, all PA cultures were allocated a score of 0 for susceptible, 0.5 for intermediate resistance or 1 for resistance for each antibiotic listed above, and the RRI calculated by dividing the sum of these by the number of antibiotics, giving a maximum score of 1. The mean RRIs for all cultures were correlated with key clinical variables monitored in CF patients (including age, FEV1, IV antibiotic days and BMI).RESULTS RRIs for non-mucoid PA exhibited moderate positive correlation with total number of IV days (r = 0.405; p < 0.001) and moderate negative correlation with FEV1 % predicted (r = -0.437; p < 0.001). RRIs were not significantly correlated with duration of colonisation, typing (clonal vs other strain) or BMI. Median RRIs were significantly higher for females (0.26, IQR 0.13-0.54) than males (0.18, IQR 0.07-0.37) for non-mucoid PA only (p = 0.03).CONCLUSIONSRRI is an easily calculated measure that correlates with other clinical variables in CF patients and enables quantitative monitoring of resistance.

AB - BACKGROUND There is a need to measure antibiotic resistance of Pseudomonas aeruginosa (PA) in cystic fibrosis (CF), either qualitatively or quantitatively, to inform patient management. The aim of this study was to develop a simple method by which resistance can be quantified by calculating a relative resistance index (RRI), and to assess correlation of RRIs with clinical variables.METHODSIn our model, RRIs were calculated based on resistance to aztreonam, ceftazidime, ciprofloxacin, colistin, meropenem, tazocin, temicillin and tobramycin. Eighty-five adults with CF and chronic PA colonisation were identified. For each, all PA cultures were allocated a score of 0 for susceptible, 0.5 for intermediate resistance or 1 for resistance for each antibiotic listed above, and the RRI calculated by dividing the sum of these by the number of antibiotics, giving a maximum score of 1. The mean RRIs for all cultures were correlated with key clinical variables monitored in CF patients (including age, FEV1, IV antibiotic days and BMI).RESULTS RRIs for non-mucoid PA exhibited moderate positive correlation with total number of IV days (r = 0.405; p < 0.001) and moderate negative correlation with FEV1 % predicted (r = -0.437; p < 0.001). RRIs were not significantly correlated with duration of colonisation, typing (clonal vs other strain) or BMI. Median RRIs were significantly higher for females (0.26, IQR 0.13-0.54) than males (0.18, IQR 0.07-0.37) for non-mucoid PA only (p = 0.03).CONCLUSIONSRRI is an easily calculated measure that correlates with other clinical variables in CF patients and enables quantitative monitoring of resistance.

KW - Journal Article

U2 - 10.1080/09674845.2017.1338500

DO - 10.1080/09674845.2017.1338500

M3 - Article

C2 - 28745144

JO - British Journal of Biomedical Science

JF - British Journal of Biomedical Science

SN - 0967-4845

ER -