Triple combination therapy with high-dose ampicillin/sulbactam, high-dose tigecycline and colistin in the treatment of ventilator-associated pneumonia caused by pan-drug resistant Acinetobacter baumannii: a case series study

Acinetobacter baumannii has evolved in recent decades as a major problem in carbapenem-resistant gram-negative nosocomial infections, associated with high mortality rates especially in intensive care units (ICUs). Recent reports highlight the increasing prevalence of resistance to colistin, a last resort therapeutic option for carbapenem-resistant A. baumannii. We retrospectively evaluated the potential efficacy, in terms of clinical and microbiological cure and mortality, of a combination of intravenous colistin and high-dose ampicillin/sulbactam and high-dose tigecycline, concurrently administered with inhaled colistin, in 10 ICU patients with ventilator-associated pneumonia (VAP) caused by carbapenem- and colistin-resistant A. baumannii strains, with high tigecycline MICs > 2μg/mL. Nine patients (90%) exhibited a successful clinical outcome, accompanied by microbiological eradication in seven of them. All clinically cured patients survived at 14 and 28 days. Acute kidney injury (AKI) was observed in one patient. In view of the increasing prevalence of pan-drug resistant A. baumannii infections in ICUs, its associated high rates of mortality and the lack of effective treatment options, we feel that there is an emerging need for our results to be further validated in larger prospective studies.