Current Opinion in Infectious Diseases

We reviewed recent data about epidemiology of Acinetobacter baumannii, resistance mechanisms, and therapeutic options for severe infections caused by multidrug-resistant strains.

A. baumannii is a major cause of nosocomial infections affecting mainly to debilitating patients in the ICU, although the spread to regular wards and to long-term care facilities is increasing. It is characterized by its great persistence in the environment and to have an extraordinary capability to develop resistance to all antimicrobials.

Carbapenems may not be considered the treatment of choice in areas with high rates of carbapenem-resistant A. baumannii. Nowadays, polymyxins are the antimicrobials with the greatest level of in-vitro activity against A. baumannii. Colistin is the most widely used in clinical practice although polymyxin B seems to be associated with less renal toxicity. Colistin is administered intravenously as its inactive prodrug colistimethate. A loading dose of 9 million IU and subsequently high, extended-interval maintenance doses (4.5 million IU/12 h) are recommended. Combination therapy instead of monotherapy increases the rates of microbiological eradication although no clinical study has demonstrated a reduction in clinical outcomes (mortality or length of stay).

The optimal treatment for multidrug-resistant A. baumannii nosocomial infections has not been established. There are no compelling data to recommend combination therapy for severe A. baumannii infections.

Whilst many guidelines recommend limiting the use of antibiotics because of the increase in antimicrobial resistance (AMR), this strategy becomes challenging when dealing with severe infections in critically ill patients. Moreover, some Gram-negative bacilli (GNB) can exhibit mechanisms of resistance that make the patient more vulnerable to recurrence of infections. We reviewed recent data on the optimal duration of antibiotic therapy in these patients.

Apart from having no additional clinical benefit at a certain point after initiation, antibiotics might have negative effects. Prolonged antibiotic exposure has been associated to development of AMR and represents a strong reason to avoid long courses of antibiotic therapy in GNB infections. Recent data suggest that also patients with severe infections, in whom source control is adequate, can be managed with short-course antibiotic therapy.

The optimal duration of antibiotic therapy depends on many factors, but overall, many infections in the critically ill can be treated with short-course antibiotic therapy (7 days or less). The integration of signs of resolution, biomarkers, clinical judgment, and microbiologic eradication might help to define this optimal duration in patients with life-threatening infections caused by GNB.

The aim of this study was to review recent data evaluating the management of central venous catheter-related bloodstream infection due to Gram-negative bacilli (GNB).

The incidence of GNB catheter-related bloodstream infection (CRBSI) has been increasing considerably in the last years, and this has raised a concern due to the high reported rate of multidrug-resistant in these infections what poses a considerable challenge for effective treatment. However, there are no specific guidelines for the management of GNB-CRBSI and optimal treatment duration has not been clearly defined. Recent studies have shown that the risk for complications is clearly different to what is stablished for Staphylococcus aureus. Therefore, a short course of antibiotic therapy might be effective once the central venous catheter (CVC) has been removed and the monitoring complications through control blood cultures or echocardiography seem to be less helpful in GNB CRBSI.

The incidence of GNB CRBSI has been increasing considerably in the last years; this has raised a concern due to the high reported rate of MDR in these infections what poses a considerable challenge for effective treatment. However, there are no specific guidelines for the management of GNB-CRBSI and optimal treatment duration has not been clearly defined. Recent studies have shown that the risk for complications is clearly different to what is stablished for S. aureus. Therefore, a short course of antibiotic therapy might be effective once the CVC has been removed and the monitoring complications through control blood cultures or echocardiography seem to be less helpful in GNB-CRBSI.