• Béatrice La Combe, Anne-Claire Mahérault, Jonathan Messika, Typhaine Billard-Pomares, Catherine Branger, Luce Landraud, Didier Dreyfuss, Fadia Dib, Laurent Massias, and Jean-Damien Ricard.
• From Assistance Publique Hôpitaux de Paris Louis Mourier Hospital, Medico-surgical Intensive Care Unit, Colombes, France (B.L.C., J.M., D.D., J.-D.R.) National Institute of Health and Medical Research, Infection Antimicrobials Modelling Evolution, Joint Research Unit 1137, Paris, France (B.L.C., A.-C.M., J.M., T.B.-P., C.B., L.L., D.D., L.M., J.-D.R.) Université Paris Diderot, Infection Antimicrobials Modelling Evolution, Joint Research Unit 1137, Sorbonne Paris Cité, Paris, France (B.L.C., A.-C.M., J.M., T.B.-P., C.B., L.L., D.D., L.M., J.-D.R.) Assistance Publique Hôpitaux de Paris, Louis Mourier Hospital, Microbiology Laboratory, Colombes, France (A.-C.M., T.B.-P., C.B., L.L.,) Assistance Publique Hôpitaux de Paris, Hôpital Bichat, Clinical Research Unit Paris Nord, Paris, France (F.D.) National Institute of Health and Medical Research, Clinical Epidemiology and Economic Evaluation Applied to Vulnerable Populations, Joint Research Unit 1123, Paris, France (F.D.) Université Paris Diderot, Clinical Epidemiology and Economic Evaluation Applied to Vulnerable Populations, Joint Research Unit 1123, Sorbonne Paris Cité, Paris, France (F.D.) Assistance Publique Hôpitaux de Paris, Hôpital Bichat, Clinical Pharmacology and Toxicology, Paris, France (L.M.).
• Anesthesiology. 2018 Dec 1; 129 (6): 1140-1148.

What We Already Know About This TopicWHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Oropharyngeal care with chlorhexidine to prevent ventilator-associated pneumonia is currently questioned, and exhaustive microbiologic data assessing its efficacy are lacking. The authors therefore aimed to study the effect of chlorhexidine mouthwash on oropharyngeal bacterial growth, to determine chlorhexidine susceptibility of these bacteria, and to measure chlorhexidine salivary concentration after an oropharyngeal care.MethodsThis observational, prospective, single-center study enrolled 30 critically ill patients under mechanical ventilation for over 48 h. Oropharyngeal contamination was assessed by swabbing the gingivobuccal sulcus immediately before applying 0.12% chlorhexidine with soaked swabs, and subsequently at 15, 60, 120, 240, and 360 min after. Bacterial growth and identification were performed, and chlorhexidine minimal inhibitory concentration of recovered pathogens was determined. Saliva was collected in 10 patients, at every timepoint, with an additional timepoint after 30 min, to measure chlorhexidine concentration.ResultsTwo hundred fifty bacterial samples were analyzed and identified 48 pathogens including Streptococci (27.1%) and Enterobacteriaceae (20.8%). Oropharyngeal contamination before chlorhexidine mouthwash ranged from 10 to 10 colony-forming units (CFU)/ml in the 30 patients (median contamination level: 2.5·10 CFU/ml), and remained between 8·10 (lowest) and 3·10 CFU/ml (highest count) after chlorhexidine exposure. These bacterial counts did not decrease overtime after chlorhexidine mouthwash (each minute increase in time resulted in a multiplication of bacterial count by a coefficient of 1.001, P = 0.83). Viridans group streptococci isolates had the lowest chlorhexidine minimal inhibitory concentration (4 [4 to 8] mg/l); Enterobacteriaceae isolates had the highest ones (32 [16 to 32] mg/l). Chlorhexidine salivary concentration rapidly decreased, reaching 7.6 [1.8 to 31] mg/l as early as 60 min after mouthwash.ConclusionsChlorhexidine oropharyngeal care does not seem to reduce bacterial oropharyngeal colonization in critically ill ventilated patients. Variable chlorhexidine minimal inhibitory concentrations along with low chlorhexidine salivary concentrations after mouthwash could explain this ineffectiveness, and thus question the use of chlorhexidine for ventilator-associated pneumonia prevention.

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