Synergistic effects of meropenem–colistin and amikacin–colistin combinations against MDR UTI isolates in hematological cancer patients in Basrah city | ||||
| Microbes and Infectious Diseases | ||||
| Articles in Press, Accepted Manuscript, Available Online from 26 August 2025 | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/mid.2025.406412.3041 | ||||
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| Authors | ||||
Athar Zaid Majid  1; Eiman Ali Saeed1; Waleed Khalid Ghanim2
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| 1Department of Clinical Laboratory Sciences, College of Pharmacy, University of Basrah, Basrah, Iraq. | ||||
| 2Departement of Pharmacology and Toxicology, College of Pharmacy, University of Basrah, Basrah, Iraq. | ||||
| Abstract | ||||
| Background: The emergence of multidrug-resistant (MDR) Gram-negative bacteria, particularly among immunocompromised patients such as those with hematological malignancies, presents a significant therapeutic challenge. Colistin has re-emerged as a crucial treatment option; however, its limitations in monotherapy—stemming from toxicity and resistance—necessitate the use of combination therapies. Objectives: This study aimed to evaluate synergistic efficacy of colistin when combined with either meropenem or amikacin against MDR uropathogens isolated from patients with hematological malignancies in vitro. Methods: A total of 30 Gram-negative isolates were obtained from urine samples. Identification and susceptibility testing were conducted using the VITEK 2 system. The minimum inhibitory concentrations (MICs) of colistin, meropenem, and amikacin both individually and in combination were determined using the checkerboard assay, and fractional inhibitory concentration index (FICI) values were calculated. The agar well diffusion method was employed for comparative visualization of antibacterial activity. Results: The combination of colistin with amikacin exhibited synergistic effects in 60% of the isolates, while the pairing of colistin with meropenem demonstrated synergy in 43.3%. Significant reductions in MIC values were observed for both combinations (p < 0.05). Agar well diffusion assays confirmed enhanced inhibition zones in most instances of synergy. Notably, E. coli and K. pneumoniae showed a higher prevalence of synergy, whereas Proteus mirabilis and Morganella morganii exhibited resistance to both combinations. Conclusion: Colistin, in combination with either meropenem or amikacin, demonstrates promising synergistic activity against MDR uropathogens. These findings underscore the potential role of combination therapy in optimizing treatment outcomes and reducing drug toxicity in patients with hematological malignancies. | ||||
| Keywords | ||||
| Keywords: Colistin; Meropenem; Amikacin; Synergy; FICI | ||||
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