Mycobacterial Outbreak Teaches a Hard Lesson About Infection Control

Richard Gawel


The Orange County Health Care Agency (OCHCA) now reports 48 cases of mycobacterial infection—15 confirmed, 33 probable, with all 48 hospitalized at some point—involving children between the ages of 3 and 9 years receiving pulpotomies at the Children’s Dental Group facility in Anaheim between March 1 and August 5, 2016. More cases may await, however, as symptoms have been appearing between 15 and 85 days after the infection. 

After the initial reports of infection, OCHCA ordered the practice to stop using water in its procedures. The agency then found mycobacteria in 5 water samples taken from the facility. While mycobacteria are common in the environment and generally pose minimal risk, OCHCA believes that the organism multiplied to dangerous levels in the waterlines of the practice’s dental units. Remediation efforts are now underway.

“Mycobacteria is naturally occurring within water. All water that comes from our treatment plants has a recommended number of colony forming units (CFUs) allowable by the federal Environmental Protection Agency (EPA), and that’s 500 CFUs or less,” said Leann Keefer, RDH, MSM, director of education and professional relations with Crosstex, which is now working with Children’s Dental Group to replace its water system.

“Mycobacerium, Legionella, and Pseudomonas are the 3 most common opportunistic pathogens, and you will find them in low numbers,” Keefer said. “The issue comes into the dental unit waterlines because those lines are so narrow, and the flow is relatively low. The water stagnates, and that’s how the biofilm develops. And they multiply into much higher numbers that have the potential for causing disease.”

When dental unit waterlines haven’t been treated, CFU counts could exceed one million as biofilm develops and sticks to the inside walls of those lines. As water flows over that biofilm, it starts to break away from the inside walls and join the stream entering the patient’s mouth. Or, it may enter any aerosol being used as part of that waterline, which then puts the dental professionals at risk as well. 

Not all people who are exposed to these bacteria, even in large quantities, necessarily get sick. Outbreaks such as this one and a similar case in Georgia in 2014 and 2015 may have affected children so significantly because their immune systems are still developing, Keefer said. Even then, only 1% of the pediatric patients who were treated at that Georgia practice came down with the infection. The Children’s Dental Group says that it treated about 500 children with pulpotomies, and only children treated for pulpotomies are at risk in the current outbreak.

“But in my mind, one child is too many. One patient is too many,” said Keefer. “This is something we could easily control.”

OCHCA has approved the Children’s Dental Group’s replacement plan for the infected water system, which will be installed by October 31. The new system will include clean water sources, institutional infection control and water routing devices, and ongoing monitoring of purification levels.

“Some people think that using distilled water in your bottle is treating the water. It’s not. The distilled water is still running through those lines. It could be contaminated,” Keefer said. “So if you’ve not been doing anything, you pretty much know that you’re going to be off the charts with CFUs, so it’s time for you to evaluate which method would be best for your particular practice.”

The ADA says that dental unit water that remains untreated or unfiltered is unlikely to meet the 500-CFU/mL standard, so one or more commercial devices and procedures designed to improve water quality should be employed. Commercially available options include independent water reservoirs, chemical treatment regimens, source water treatment systems, daily draining and air purging regimens, and point of use filters.

The Crosstex DentaPure cartridge, for example, uses a matrix of iodinated resin beads to treat water passing through the dental unit waterline during the course of a year to control bacteria. The isotopic iodine it uses is protein-free, so there is no risk of an allergic reaction. It doesn’t require any tablets or routine shocking, nor does it use any silver or have any special disposal requirements. And, distilled water isn’t required.

“DentaPure is basically a NASA technology that was developed to provide safe water for our astronauts while they are in space, and it’s still being used on the International Space Station today,” said Keefer. “As the water flows into the cartridge and over those iodine beads, the iodine is released at 2 to 4 parts per million, which then actively kills the bacteria that’s found in the dental unit waterlines.”

Also, the ADA recommends strict adherence to maintenance protocols and consultation with dental unit manufacturers before initiating any waterline treatment protocol. Waterline treatment schedules should include water quality monitoring as well via self-contained and easy to use water quality indicators, the ADA says. In-office testing kits are available, and many laboratories provide mail-in testing services.

“Our testing has shown that we not only meet but exceed the EPA recommendations. We can claim 200 CFUs or less with the DentaPure unit for a period of one year after installation,” said Keefer. “That’s another huge advantage because it’s not something that your staff has to do daily, that they have to remember about compliance. Once they put it into the system, it’s there for a year.”

Crosstex will remind users when it’s time to replace their DentaPure unit each year, so practices basically can forget about it until it’s time to swap in a new one. However, the company does provide iodinated test strips for users who want to verify that the cartridge is operating properly and releasing between 2 and 4 parts per million of iodine. Users also can send test samples of water to Crosstex for analysis.

“And that’s a great teaching tool for the staff because when it’s coming back at less than 200 CFUs. That’s positive reinforcement that they’re doing the right thing,” said Keefer.

Furthermore, Keefer urges users to follow all Centers for Disease Control and Prevention guidelines for operation. In between each patient, for instance, dental staff should flush the lines for 20 to 30 seconds. This doesn’t remove the biofilm from the inside of the dental unit waterlines, but it does help remove any free-floating oral bacteria and other contaminants that may have backflowed into the system during dental treatment.

The Organization for Safety, Asepsis, and Prevention offers additional resources on dental unit waterline protection and says that dental healthcare personnel should be trained in water quality, biofilm formation, water treatment methods, and appropriate maintenance protocols. Its online materials also detail self-contained water systems, chemical agents, and filters, sterile water delivery systems, and source water treatments. The most overlooked strategy for preventing infections, though, may be communication.

“We think these incidents are devastating for the patients and their families. But it’s also unfortunate that dental practices are the source of these contaminations because they largely are preventable,” Keefer said. “So we need to get the awareness out there, and patients should be asking ‘What are you doing to treat the dental unit waterlines?’ And the staff should be excited to share, ‘This is what we’re doing to keep the dental unit waterlines safe.’”

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