Antibiotics to help reduce mortality and respiratory infections in people receiving intensive care in hospital

Infections acquired in intensive care units (ICUs) are important complications of the treatment of patients with very severe diseases who need ventilation (mechanical breathing support). Some people will die because of these infections. Considerable efforts have been made to evaluate methods for reducing this problem; one of these involves the use of antibiotics administered as preventative intervention, usually referred to as selective decontamination of the digestive tract (SDD). This review includes 36 studies involving 6914 patients treated in ICUs to investigate whether the administration of antibiotics prevents the development of infections. Antibiotics were administered in two different ways. In some studies antibiotics were applied both directly to the oropharynx via a nasogastric tube (topical) and intravenously (systemic). In other studies they were applied only topically. Our results show that when patients received the combination of topical plus systemic antibiotics there were less infections and deaths. When patients received only topical treatment there were less infections but the number of deaths was not changed. Although this treatment seems to work it is not widely used in clinical practice because there is concern about the possible development of antibiotic resistance (that is, bacteria become unresponsive to drugs).

Authors' conclusions: 

A combination of topical and systemic prophylactic antibiotics reduces RTIs and overall mortality in adult patients receiving intensive care. Treatment based on the use of topical prophylaxis alone reduces respiratory infections but not mortality. The risk of resistance occurring as a negative consequence of antibiotic use was appropriately explored only in one trial which did not show any such effect.

Read the full abstract...

Pneumonia is an important cause of mortality in intensive care units (ICUs). The incidence of pneumonia in ICU patients ranges between 7% and 40%, and the crude mortality from ventilator-associated pneumonia may exceed 50%. Although not all deaths in patients with this form of pneumonia are directly attributable to pneumonia, it has been shown to contribute to mortality in ICUs independently of other factors that are also strongly associated with such deaths.


To assess the effects of prophylactic antibiotic regimens, such as selective decontamination of the digestive tract (SDD) for the prevention of respiratory tract infections (RTIs) and overall mortality in adults receiving intensive care.

Search strategy: 

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2009, issue 1), which contains the Cochrane Acute Respiratory Infections (ARI) Group's Specialised Register; MEDLINE (January 1966 to March 2009); and EMBASE (January 1990 to March 2009).

Selection criteria: 

Randomised controlled trials (RCTs) of antibiotic prophylaxis for RTIs and deaths among adult ICU patients.

Data collection and analysis: 

At least two review authors independently extracted data and assessed trial quality.

Main results: 

We included 36 trials involving 6914 people. There was variation in the antibiotics used, patient characteristics and risk of RTIs and mortality in the control groups. In trials comparing a combination of topical and systemic antibiotics, there was a significant reduction in both RTIs (number of studies = 16, odds ratio (OR) 0.28, 95% confidence interval (CI) 0.20 to 0.38) and total mortality (number of studies = 17, OR 0.75, 95% CI 0.65 to 0.87) in the treated group. In trials comparing topical antimicrobials alone (or comparing topical plus systemic versus systemic alone) there was a significant reduction in RTIs (number of studies = 17, OR 0.44, 95% CI 0.31 to 0.63) but not in total mortality (number of studies = 19, OR 0.97, 95% CI 0.82 to 1.16) in the treated group.