Burkholderia cepacia-contaminated dentures possibly cause pneumonia

In Japan, dentures are commonly immersed in commercially available storage solutions sold in tablet form and dissolved in tap water for use. These denture storage solutions are often marketed as ‘anti-bacterial’, which often leads to misunderstanding of their proper usage. We report a case in which a patient was suspected of developing pneumonia due to wearing dentures that were immersed in a denture storage solution contaminated by Burkholderia cepacia.

An 84-year-old man was admitted with a ruptured abdominal aortic aneurysm. Open surgical repair was performed immediately. After surgery, open abdomen management was required for 4 days to treat the abdominal compartment syndrome. We extubated the patient on postoperative day (POD) 5 and reintubated him on POD 8 due to hypoxic respiratory failure. We performed a tracheotomy on POD 14 and transverse colon resection on POD 22 for ischemic colitis. After the last surgery, he was on a mechanical ventilator due to hypoxia. He did not require sedative drugs during the day and was in a state where he could communicate. The patient started wearing his dentures on POD 24 for two consecutive days. He had an acute fever higher than 38 °C from the night of the day of putting on his dentures. On the following day, he developed a fever over 39 °C with decreased consciousness. After removal of the dentures, the fever decreased and he regained consciousness. He wore the dentures again during the day on POD 30. The fever returned, climbing up to 38 °C at night. On POD 32, he had an acute fever of 40 °C and fell into septic shock at night after wearing the dentures. He rapidly recovered from shock by fluid resuscitation and the use of catecholamine. He had mucopurulent sputum; a plain chest radiograph showed pneumonia with bilateral infiltrates. C-reactive protein levels in the blood increased up to 24.8 mg/mL. We stopped using the dentures and administrated antimicrobials (meropenem); the patient gradually recovered from pneumonia.

We performed sputum culture at days 2, 3, 4, 5, 8, and 10 after the patient wore his dentures. B. cepacia were isolated from all collected samples. We performed blood culture at days 0, 2, and 8 after wearing the dentures and did not detect any isolates. At a later time, the patient died from persistent bleeding and perforation of the digestive tract 50 days after his initial admission to care.

B. cepacia isolated from sputum of the patient and denture storage solution were subjected to pulsed-field gel electrophoresis using the commercially available B. cenocepacia ATCC BAA-245. The high-molecular-weight chromosomal DNA was prepared according to the method of Murray et al. (1991), and the DNA sample in a small slice of an agarose plug in 200 μL of reaction buffer was digested with 30 U of SpeI (New England Bio Labs, USA). Pulsed-field gel electrophoresis was carried out with the Bio-Rad Gene Path system (Bio-Rad, USA) in 1% agarose gel in 0.5 × TBE buffer at 14 °C with a linear ramp time of 1–23 s over a period of 18.5 h. Thereafter, the gels were stained with ethidium bromide and photographed.

Since the in-use denture storage solution was colonized, the denture storage solution was switched to 0.1% benzalkonium chloride solution containing 8 vol% ethanol. The combination of benzalkonium and diluted ethanol is useful for prevention of microbial growth, as they act synergistically (Oie & Koshiro 1984). After changing to this denture storage solution (replacing the solution every 7 days), a total of 48 samples collected from the first 7 days of use were examined over a 1-year period. These samples were used in 15 patients, and none of the samples were colonized.

It is well known that patients with cystic fibrosis and chronic granulomatous disease are predisposed to B. cepacia infections. These diseases are relatively uncommon in the Japanese population. Additionally, B. cepacia infections have been very rare in our past ICU admissions. We began to carry out an environmental investigation due to increased cases of B. cepacia repeatedly being isolated from the sputum of our patient with pneumonia. Based on this investigation, it is likely that the cause of pneumonia in the patient is due to the denture storage solution that is contaminated with B. cepacia. We observed the patient recovering from pneumonia after stopping the use of dentures and found evidence that B. cepacia isolated from the sputum of the patient and from the denture storage solution have the same DNA fingerprint. These findings suggest the denture storage solution as the main source of infection. It is likely that the contaminated denture solution entered the trachea and caused B. cepacia pneumonia in this patient due to the prolonged supine positioning.

B. cepacia contamination in manufacture-related processes have been reported in various products, such as chlorhexidine mouthwash solution, alcohol-free mouthwash, saline flush syringes, lipid emulsion stoppers, disinfectant solution, ultrasonography gel, and analgesic gel (Berkelman et al. 1981; Anderson et al. 1990; Brook 2002; Doit et al. 2004; Molina-Cabrillana et al. 2006; Song et al. 2018; Brooks et al. 2019; Viderman et al. 2020; Wong et al. 2020; Zou et al. 2020; Bilgin et al. 2021). B. cepacia contamination in pharmacy-related processes have been identified in fentanyl injection preparations and diluted chlorhexidine preparations (Lee et al. 2013; Moehring et al. 2014). B. cepacia contamination has also been detected in products used in patients' rooms, such as Ringer's lactate solution that has been split for use (De Smet et al. 2013). Similarly, we have also reported cases of manufacture-related B. cepacia contamination in commercially available ethacridine lactate (acrinol) products and disinfectant-soaked unwoven cleaning cloth, as well as contamination in products used in patients' rooms such as antiseptics (0.02% benzalkonium chloride) and aerosol solutions containing antibiotics (Oie & Kamiya 1995, 1996; Hakuno et al. 2010). In all our reported cases, 10²–10⁶ cfu/mL of B. cepacia were detected in pure culture. Our findings highlight the risk of B. cepacia contamination in products that are used daily by patients in addition to any pharmaceutical products.

We thank Teruko Nakazawa, an emeritus professor at Yamaguchi University for useful suggestions.

All relevant data are included in the paper or its Supplementary Information.

The authors declare there is no conflict.