Time-kill and post-antibiotic effect of colistin at different static concentrations in in vitro Acinetobacter baumannii

Rsm Rasidin; Z Suhaili; Afs Mohamed; R Hod; V Neela; S Amin-nordin

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Time-kill and post-antibiotic effect of colistin at different static concentrations in in vitro Acinetobacter baumannii

Author: Rasidin, R.S.M. ¹ ; Suhaili, Z. ² ; Mohamed, A.F.S. ³ ; Hod, R. ⁴ ; Neela, V. ¹ ; Amin-Nordin, S. ¹
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1. Department of Medical Microbiology and Parasitology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
2. School of Animal Sciences, Faculty of Bioresources and Food Industry, Universiti Sultan Zainal Abidin, Besut Campus, 22200 Besut, Terengganu, Malaysia
3. Herbal Medicine Research Centre, Institute for Medical Research, Kuala Lumpur, Malaysia
4. Department of Human Anatomy, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
Publication Type:Journal Article
From:Tropical Biomedicine 2020;37(No.2):471-481
CountryMalaysia
Language:English
Abstract: Nosocomial infection caused by Acinetobacter baumannii is common among immunocompromised patients. Treatment strategy is limited due to rapid resistance development and lack of novel antibiotic. Colistin has been the last line therapy with good in vitro activity against infections caused by multi-drug resistance A. baumannii. However, pharmacological updates are required to support dosing optimisation. This study aimed to determine the time-kill kinetic and resistance development after antibiotic exposure as well as post-antibiotic effect of colistin at different static concentrations in in vitro A. baumannii system. The static in vitro time-kill and post-antibiotic effect experiments were conducted against two clinical isolates as well as one reference isolate ATCC 19606. Time-kill and postantibiotic effect were studied at colistin concentrations ranging from 0.25MIC to 16.0MIC and 0.5MIC to 4.0MIC, respectively. Post-exposure resistance development was examined in time-kill study. Killing activity and post-antibiotic effect were in a concentration-dependent manner. However, delayed killing activity indicates colistin tolerance. Development of resistance after exposure was not detected except for the ATCC 19606 strain. Dosing suggestion based on the observations include administration of supplemental dose 3 MIU at 12 hours after loading dose, administration of maintenance dose 9 MIU in two divided doses and application of extended interval in renal adjustment dose. However, the information is applicable for non-colistin-heteroresistance A. baumannii with colistin MIC < 1.0 mg/L. As for heteroresistance and strain with colistin MIC > 1.0 mg/L, combination therapy would be the more appropriate treatment strategy.
Full text:8.2020my11361.pdf