Summary
Urinary tract infections caused by ureasplitting bacteria are severe clinical conditions and very difficult to treat due to their association with calculi, and because such bacteria form ammonium hydroxide raising the urinary pH and thereby creating an unfavourable condition for the action of most antimicrobials. We tested ofloxacin, norfloxacin, nalidixic acid, amoxicillin, amoxicillin-clavulanic acid, gentamicin, co-trimoxazole and nitrofurantoin against 143 gram-negative and 99 gram-positive bacteria, all ureasplitting, isolated from patients with urinary tract infections. All drugs were tested using media at two different pHs (pH 7.4 and PH 8.5) and two inoculum sizes (104 and 106 cfu). Although ofloxacin and norfloxacin had a similar spectrum of activity, ofloxacin had somewhat greater intrinsic activity against grampositive organisms. MICs of ofloxacin for 90% ofProteus mirabilis, indole-positiveProteus spp.,Klebsiella pneumoniae, Staphylococcus aureus, coagulase-negative staphylococci and theCorynebacterium group D2 were ≥ 4 mg/l. The activity of the other drugs varied, but there were many strains resistant to these antimicrobials. The pH and inoculum size did not significantly affect the activity of ofloxacin so that this drug should be useful for the treatment of urinary tract infections caused by the commonest urea-splitting bacteria involved in such infections.
Zusammenfassung
Harnwegsinfektionen, die durch harnstoffspaltende Bakterien verursacht sind, stellen eine schwierige klinische Situation dar, da sie mit Steinbildung assoziiert sind und zudem infolge von Ammoniumhydroxydbildung den pH des Urins anheben und somit ungünstige Voraussetzungen für die Wirkung der meisten antimikrobiellen Substanzen schaffen. Wir haben Ofloxacin, Norfloxacin, Nalidixinsäure, Amoxicillin, Amoxicillin-Clavulansäure, Gentamicin, Co-trimoxazol und Nitrofurantoin auf ihre Aktivität gegen 143 gramnegative und 99 grampositive, harnstoffspaltende Bakterien geprüft, die von Patienten mit Harnwegsinfektionen isoliert worden waren. Die Testung aller Antibiotika wurde mit Medien bei zwei verschiedenen pH-Werten (pH 7,4 und pH 8,5) und mit zwei verschiedenen Inokulumgrößen (104 und 106 KBE) vorgenommen. Trotz eines weitgehend ähnlichen Wirkungsspektrums war die intrinsische Aktivität von Ofloxacin gegen grampositive Erreger höher. Die MHK90-Werte von Ofloxacin fürProteus mirabilis, indolpositiveProteus spp.,Klebsiella pneumoniae, Staphylococcus aureus, koagulasenegative Staphylokokken undCorynebacterium Gruppe D2 lagen bei ≤ 4 mg/l. Die übrigen Antibiotika besaßen unterschiedliche Aktivität, doch waren viele der getesteten Stämme gegen diese Substanzen resistent. Die Aktivität von Ofloxacin wurde durch den pH und die Inokulumgröße nicht wesentlich beeinflußt. Es ist daher anzunehmen, daß sich Ofloxacin für die Behandlung von Harnwegsinfektionen durch die häufigsten harnstoffspaltenden Erreger eignet.
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Torres, A., Fernández-Roblas, R., Méndez, B. et al. Comparative activity of ofloxacin and seven other antimicrobials against urea-splitting microorganisms. Infection 14 (Suppl 4), S233–S236 (1986). https://doi.org/10.1007/BF01661279
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DOI: https://doi.org/10.1007/BF01661279