From the Research
Yes, when two isolates of the same bacterial species with different antibiotic susceptibility patterns are found in a urine culture, an antibiotic that is effective against both isolates should be used. This approach ensures complete eradication of the infection and prevents treatment failure. For example, if E. coli isolates show resistance to trimethoprim-sulfamethoxazole in one isolate but susceptibility in the other, while both are susceptible to nitrofurantoin, then nitrofurantoin (typically 100mg orally twice daily for 5-7 days for uncomplicated UTIs) would be the appropriate choice, as supported by the most recent study 1. The presence of different susceptibility patterns within the same species suggests either multiple strains of the bacteria or the emergence of resistance in a subpopulation. Using an antibiotic effective against only one isolate could lead to treatment failure as the resistant population would continue to multiply. In complicated cases or when few antibiotics are effective against both isolates, consultation with an infectious disease specialist may be necessary to determine the optimal treatment regimen, considering the high rates of antibiotic resistance and multi-drug resistance revealed in recent studies 1. This approach helps prevent recurrent infections and reduces the risk of developing further antibiotic resistance. Some key antibiotics that could be considered for coverage against common uropathogens include fosfomycin, cefoperazone/sulbactam, and meropenem for Gram-negative microorganisms, and fosfomycin, cefoperazone/sulbactam, meropenem, and amoxicillin/clavulanate for Gram-positive microorganisms, as indicated by the study 1. However, the choice of antibiotic should always be guided by the specific susceptibility patterns of the isolates and local resistance patterns, emphasizing the importance of urine culture and sensitivity testing 2, 3, 1.