2024. Factors Affecting Treatment Outcome of Extensively Drug-resistant Acinetobacter baumannii and Pseudomonas aeruginosa Infection under Colistin Combination Therapy
Session: Poster Abstract Session: Antimicrobial Resistant Infections: Treatment
Saturday, October 29, 2016
Room: Poster Hall
  • Factors Associated with Treatment Outcome of Extensively Drug-Resistant-ID week 2016 poster.pdf (710.0 kB)
  • Background: Extensively drug-resistant (XDR) Acinetobacter baumannii and Pseudomonas aeruginosa are generally sensitive to colistin. However colistin combination therapy (CCT) is advocated to avoid emergence of resistant bacteria. However, the factors affecting treatment outcome in XDR bacterial infection under CCT have not often been addressed.

    Methods: A prospective observational study over a 14-day period conducted between October 2014 and January 2016 in inpatients with XDR A. baumannii or P. aeruginosainfection receiving CCT namely imipenem, meropenem, doripenem, ceftazidime, piperacillin/tazobactam, and tigecycline. Patients’ basic clinical data and plasma colistin levels were collected. Blood samples were collected on day 0, day 3, 7 ,and 10. Plasma colistin levels were measured using liquid chromatography coupled to quadruple time-of-flight mass spectrometry.

    Results: Total 34 patients enrolled. Median duration of CCT was 10 days with 61% of patients achieved the target colistin level without any difference between the 2 groups. Imipenem combination therapy had a trend to produce the highest microbiological success rates (6/8 patients, 75%) compared with others. All bacteremic and urinary-tract-infection patients had 100% microbiological success while others did not (p-value <0.0001). There was no significant correlation between treatment outcome, colistin levels, and acute kidney injury (AKI). Prevalence of AKI was 10 folds higher among individuals with age >65 years old (95% CI, 1.05-95.23) and 1.625 folds greater when GFR <60 ml/min (95% CI, 1.19-2.20). Higher APACHE II scores predicted higher mortality (p-value=0.031).

    Conclusion: Firstly, current recommended dosing regimen may not be a consensus in such clinical setting; secondly, plasma colistin level may not be a good indicator for assessing treatment efficacy both in terms of overall clinical response and microbiological success; thirdly, synergistic effect from an appropriate partner antimicrobial agent maybe another consideration in choosing a CCT formulation to ensure optimal clinical response and potentially a lower dosage of colistin; fourthly, CCT is not efficacious equally for all sites of bacterial infection, and lastly APACHE score is still the key determining mortality outcome regardless of treatment regimen.

    Porpon Rotjanapan, MD1, Parinda Kongprasom, M.D.2, Pakwan Bunupuradah, M.Sc. (Clinical pharmacy)3, Saranya Auparakkitanon, Ph.D.4, Jatupon Krongvorakul, M.D.4 and Jetjamnong Sueajai, B.Sc.4, (1)Division of Infectious Disease, Department of Medicine, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand, (2)Medicine, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand, (3)Pharmacy, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand, (4)Pathology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand


    P. Rotjanapan, None

    P. Kongprasom, None

    P. Bunupuradah, None

    S. Auparakkitanon, None

    J. Krongvorakul, None

    J. Sueajai, None

    Findings in the abstracts are embargoed until 12:01 a.m. CDT, Wednesday Oct. 26th with the exception of research findings presented at the IDWeek press conferences.