Topical povidone iodine inhibits bacterial growth in the oral cavity of patients on mechanical ventilation: a randomized controlled study

Abstract

Background: Topical 0.12% chlorhexidine has been used widely to prevent ventilator-associated pneumonia in patients undergoing mechanical ventilation. However, it is not approved for mucosal application in Japan. The aims of this study were to investigate if topical povidone iodine (i) inhibits bacterial growth and (ii) disrupts the balance of the oral microbiota.

Methods: This randomized controlled clinical trial included 23 patients who underwent mechanical ventilation in the intensive care unit. The patients were divided randomly into two groups: the intervention group (n = 16) and the control group (n = 7). All patients received oral cleaning with 3% hydrogen peroxide, followed by irrigation with tap water. The patients in the intervention group received 10% povidone iodine applied topically to the oral cavity. The concentration of total bacteria in the oropharyngeal fluid were determined before, immediately after, 1 h, 2 h, and 3 h after oral care using the Rapid Oral Bacteria Quantification System, which is based on dielectrophoresis and impedance measurements. The number of streptococci, methicillin-resistant Staphylococcus aureus, Streptococcus pneumoniae, Pseudomonas aeruginosa, Porphyromonas gingivalis, and Candida albicans before, immediately after, 1 h, and 3 h after oral care were estimated based on real-time polymerase chain reaction data.

Results: After irrigation of the oral cavity, the number of bacteria decreased, but increased again at 1 h after oral care in the control group; however, in the intervention group, the concentration of bacteria was significantly lower than that in the control group at 1 hour (p = 0.009), 2 h (p = 0.001), and 3 h (p = 0.001) after oral care. The growth of all bacterial species tested was inhibited in the intervention group at 3 h after oral care, suggesting that povidone iodine did not disturb the balance of the oral microbiota.

Conclusions: Topical application of povidone iodine after cleaning and irrigation of the oral cavity inhibited bacterial growth in the oropharyngeal fluid of patients on mechanical ventilation while not disrupting the balance of the oral microbiota.

Trial registration: University Hospitals Medical Information Network Clinical Trials Registry (UMIN-CTR), UMIN000028307. Registered 1 September 2017.

Keywords: Mechanical ventilation; Oral bacteria; Oral care; Povidone iodine; Saliva.

Fig. 1

Oral care method. a Wiping of the oral mucosa with 3% hydrogen peroxide; b irrigation with tap water; c topical application of 10% povidone iodine

Fig. 2

Artificial DNA sequences used in real-time polymerase chain reaction

Fig. 3

Changes in the total bacterial count before and after oral care in the intervention and control groups. There was no significant difference in the total bacterial count between the 2 groups before and after oral care, but at 1, 2, and 3 h after application of iodine povidone, it in the intervention group was significantly lower than that in the control group

Fig. 4

Changes in the count of each microorganism before and after oral care in the intervention and control groups. Each microorganism decreased at 1–3 h after application of povidone iodine, suggesting that this disinfectant does not disturb the oral microbiota or promote the growth of bacteria resistant to antibiotics (e.g., MRSA) or fungi