a new trial conducted by the canadian critical care trials group investigated the impact of different diagnostic approaches on outcomes of patients suspected of having ventilator - associated pneumonia ( vap ) .
immediate administration of adequate antibiotic therapy is critical to improving survival in patients with vap . at the same time , appropriate antimicrobial stewardship includes not only limiting the use of inappropriate agents in patients with vap , but also improving our ability to diagnose and exclude infection in the intensive care unit ( icu ) setting in order to avoid administering antibiotics to patients without bacterial infection .
this recent published randomized trial   comparing the quantitative culture of bronchoalveolar lavage ( bal ) fluid and the culture of endotracheal aspirate in critically ill patients with suspected vap adds to the information presented by four previous trials [ 5 - 8 ] .
the canadian critical care trials group found that the two diagnostic techniques were associated with similar clinical outcomes and similar overall use of antibiotics ( table 1 ) .
several considerations should be taken into account , however , to appropriately evaluate the possible impact of diagnostic techniques on the individual ( patient morbidity and mortality ) and on the collective ( emergence and dissemination of antibiotic - resistant strains ) outcomes .
outcomes and antibiotics in the canadian critical care trials group study   no differences were statistically significant .
first , as clearly underlined by kollef in his related editorial , the exclusion of patients previously colonized or infected with methicillin - resistant staphylococcus aureus or pseudomonas species and the exclusion of those patients having previously received the ' study drugs ' ( that is , meropenem and/or ciprofloxacin ) resulted in a low rate of studied patients with ' high - risk ' pathogens responsible for vap .
a proportion of less than 12% of difficult - to - treat pathogens , such as p. aeruginosa , acinetobacter spp .
, stenotrophomonas maltophilia , and/or methicillin - resistant s. aureus , as compared with more than 30% in the french study , diminishes the usefulness of the results of this study in real life .
second , 29% of patients managed using bal had new antibiotics initiated within 3 days before randomization , probably after the onset of the first signs in relation to vap , which is problematic when using quantitative culture techniques . in this case , a negative finding or a result below the usual threshold of 10colony - forming units / ml could indicate either that the patient has been successfully treated for pneumonia and the bacteria are eradicated , or that there was no lung infection to begin with .
these authors did not give any information on how decisions regarding antibiotic treatment were taken in this group of patients .
third , the authors report a relatively high rate ( 14% ) of inappropriate initial empirical therapy in the bal group . as indicated above , the low frequency of high - risk , difficult - to - treat pathogens responsible for pneumonia can not explain such a disappointing result , when compared with the 0.5% rate of inappropriate initial therapy reported by fagon and coworkers in the invasive strategy group .
the most probable explanation is that all patients included in this study were also randomized to receive a fixed combination therapy or monotherapy as initial treatment : meropenem plus ciprofloxacin or meropenem alone .
several studies have clearly established that initial antimicrobial therapy in patients with vap should be customized to local epidemiology at the icu level .
fourth , even on day 6 the rate of targeted therapy was only 74.2% in the bal arm , underlining the fact that , in many patients managed using this diagnostic technique , early de - escalation was not performed although clearly indicated .
unfortunately , information on how decision algorithms were followed in the two study arms once cultures were available ( as soon as day 2 or day 3 ) was not given .
obviously , the potential benefit of using a diagnostic tool such as bal for safely restricting unnecessary antimicrobial therapy in such a setting can only be obtained when decisions regarding antibiotics are closely linked to bacteriological  both direct examination and cultures  results . in the current study ,
bal was not used for identifying patients with vap who needed antimicrobial therapy ; this decision was essentially left to the icu physicians in charge of the included patients on the basis of their clinical judgment , even when bal culture results were < 10colony - forming units / ml .
interestingly , the proportion of ' confirmed pneumonia ' was 86% in the bal group and 83% in the endotracheal aspirate group .
in contrast to previous recommendations concerning the use of quantitative bal , therefore , many patients with quantitative culture results below the cut - off point of 10colony - forming units / ml continued to receive antibiotics , even after day 3 .
this could entirely explain why there was a similar use of antibiotics in the two study arms .
finally , a major benefit of a negative bal specimen may be to direct attention away from the lungs as the source of fever and , in the absence of antibiotic interference , to more readily diagnose other potential sites of infection .
delaying diagnosis or definitive treatment of the true site of infection may lead to prolonged antibiotic therapy and to induction of additional dysfunction . in the current trial ,
we are left with uncertainties regarding the numbers of extrapulmonary infection in the two arms of the trial , as well as how long the recommended duration of therapy in patients with vap should be and the how patients were managed in case of a second episode . in summary , even if the results of the canadian study are consistent with those of the three spanish trials ( table 2 ) in which antimicrobial treatment was also initiated in all suspected patients and rarely withheld in patients with negative cultures , our own bias is that additional studies will be needed before one can conclude that a strategy based on the systematic collection of distal pulmonary secretions prior to the introduction of new antibiotics and quantitative culture techniques is useless . in real life ,
the key issue is to be able to adhere to a de - escalation strategy , which is the only way to curb the unnecessary use of antibiotics in the icu .
the predominant impact of pretest opinion and the absence of clear bacteriological - based decision algorithms in the current study may unfortunately encourage physicians to pursue antibiotics in most patients after 2 days , even once results of bacterial cultures are available .
ruiz et al .   reported the total duration of antibiotic treatment ; p = 0.48 .
the canadian critical care trials group   reported antibiotic - free days ; p = 0.86 .
bal = bronchoalveolar lavage ; icu = intensive care unit ; vap = ventilator - associated pneumonia .
 the results of a recently published canadian study suggest that bronchoalveolar lavage and endotracheal aspiration are associated with similar clinical outcomes and similar overall use of antibiotics in critically ill patients with suspected ventilator - associated pneumonia ( vap ) . 
 the study , however , does not provide convincing information on the best strategy to diagnose vap , to accurately choose initial treatment and to exclude vap in order to avoid administering antibiotics to patients without bacterial infection . 
 in fact , this trial has several limitations or drawbacks : patients at risk for developing vap due to pseudomonas aeruginosa or methicillin - resistant staphylococcus aureus were excluded , far from the real - life scenario ; a significant number of patients were receiving recent antimicrobial therapy at the time of sampling , with , consequently , difficult - to - interpret culture results ; randomization of included patients for initial treatment  meropenem plus ciprofloxacin or meropenem alone  resulted in a high rate of inappropriate initial empirical therapy due to the absence of customization to local epidemiology ; and the initial decision to treat and the re - evaluation at day 3 were , in fact , based on clinical judgment and not on direct examination and quantitative culture results . in summary , because antimicrobial treatment was initiated in all suspected patients and was rarely withheld in patients with negative cultures , the study does not suggest an appropriate strategy for improving the use of antibiotics in intensive care unit patients . such a strategy has two requirements : immediate administration of adequate therapy in patients with true vap , and avoidance of administering antibiotics in patients without bacterial infection . 
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