Prospective, comparative clinical study between high-dose colistin monotherapy and colistin-meropenem combination therapy for treatment of hospital-acquired pneumonia and ventilator-associated pneumonia caused by multidrug-resistant Klebsiella pneumoniae.

OBJECTIVES: In clinical practice, colistin is used as combination therapy to improve its antibacterial activity, despite the consequent increase in toxicity. This prospective, comparative study evaluated the effectiveness and adverse effects of using colistin alone at a loading dose of 9 million international units (MIU) followed by 3 MIU every 8h (q8h) versus colistin+meropenem 1g q8h in treating multidrug-resistant (MDR) Klebsiella pneumoniae-induced hospital-acquired pneumonia (HAP) or ventilator-associated pneumonia (VAP). The primary outcome measure was in-hospital mortality. The secondary measure was the occurrence of colistin toxicity.

METHODS: A total of 60 patients were divided into two groups (30 patients each); the first group received intravenous colistin at a mean daily dose of 8.304 MIU and the second group received colistin 8.58 MIU combined with meropenem (mean daily dose of 2.88g for 15 days).

RESULTS: The colistin-meropenem combination group showed a significant decrease in mortality versus colistin alone [16.7% (5/30) vs. 43.3% (13/30); P=0.047]. The improved clinical response mediated by combination therapy was not associated with any significant nephrotoxicity, hepatotoxicity or neurotoxicity. Moreover, the 42 surviving patients showed normal procalcitonin values associated with a decrease in SOFA score, whilst 12 of them showed significantly elevated C-reactive protein (CRP) (P=0.0002).

CONCLUSIONS: This study revealed the superiority of colistin-meropenem combination therapy over colistin monotherapy in the treatment of MDR K. pneumoniae-induced HAP or VAP and highlights the advantage of procalcitonin over CRP as a marker for eradication of sepsis and suspension of therapy.