Upload
andrew-tung-nguyen
View
218
Download
0
Embed Size (px)
Citation preview
8/3/2019 Legion Ella and Dental Water Lines
http://slidepdf.com/reader/full/legion-ella-and-dental-water-lines 1/28
Legionnaires’ Disease Outbreak
June 21 to July 4, 2011
6 cases of Legionnaires’ Disease reported
Sent letters to guests who stayed at the Ariaduring this 2-week period
High levels of Legionella bacteria detected
in water supplying several guest rooms
Follow-up testing did not detect the bacteriashould you be tested, did you develop symptom, who is at risk, could you be infected, could you transmit.
8/3/2019 Legion Ella and Dental Water Lines
http://slidepdf.com/reader/full/legion-ella-and-dental-water-lines 2/28
Legionnaires’ Disease
Epidemic of pneumonia at the Pennsylvania State
American Legion convention 1976
221 people affected, 34 died
An upscale hotel , the Bellevue-Stratford, closed due to
the publicity
Causative mo not identified until 1977 (6 months
later) – fastidious gram-negative bacillus
Prior outbreaks (1940s, 1950s, 1960s)
Unsolved epidemic of nonpneumonic febrile illness
in Pontiac, Michigan (1960s)
pontiac fever
8/3/2019 Legion Ella and Dental Water Lines
http://slidepdf.com/reader/full/legion-ella-and-dental-water-lines 3/28
2010 Selfridge Air National
Guard Base Outbreak July 12-24 – at least 31 people with an URT
illness
6 people diagnosed with Legionnaires’disease
8/3/2019 Legion Ella and Dental Water Lines
http://slidepdf.com/reader/full/legion-ella-and-dental-water-lines 4/28
Legionella pneumophila
Gram negative aerobic bacillus
Single polar flagellum, multiple pili
Nutritionally fastidiousMedium: charcoal yeast extract pH 6.9
Usually find as intracellular organisms
In nature, found inside protozoa
In vivo replicates inside macrophages
8/3/2019 Legion Ella and Dental Water Lines
http://slidepdf.com/reader/full/legion-ella-and-dental-water-lines 5/28
Ecology: Legionella pneumophila
Natural habitat: rivers, lakes, streams,
thermally polluted waters
Survives water treatment process
Chlorine tolerant
Proliferate in man-made habitats
Cooling towers, water distribution systems
8/3/2019 Legion Ella and Dental Water Lines
http://slidepdf.com/reader/full/legion-ella-and-dental-water-lines 6/28
Transmission: Legionella pneumophila
Aerosolization
Aspiration
Instillation into lung
Not transmissible person to person
8/3/2019 Legion Ella and Dental Water Lines
http://slidepdf.com/reader/full/legion-ella-and-dental-water-lines 7/28
Diseases
Legionnaires’ disease
Non-specific clinical presentation
Early flu-like symptoms
Mild cough early, slightly productive
Pontiac fever
Acute self-limiting flu-like illness
Common
8/3/2019 Legion Ella and Dental Water Lines
http://slidepdf.com/reader/full/legion-ella-and-dental-water-lines 8/28
Pontiac Fever
>90% exposed develop symptoms
acute, self-limiting flu-like illness
IP = 24-48 hrs
malaise, myalgia, fever, chills, headache
only symptomatic tx necessary
complete recovery within 1 week
8/3/2019 Legion Ella and Dental Water Lines
http://slidepdf.com/reader/full/legion-ella-and-dental-water-lines 9/28
Legionnaires’ Disease
Pneumonia is most prominent finding
Spectrum of illness from mild cough to
stupor with multi-system failure
IP = 2-10 days
L. pneumophila one of 3 most common
etiologic agents of community-acquired
pneumonia
8/3/2019 Legion Ella and Dental Water Lines
http://slidepdf.com/reader/full/legion-ella-and-dental-water-lines 10/28
Legionnaires’ Disease
Risk factors
Cigarette smoking
Chronic lung disease
Advanced age
Immunosuppression
Treatment: erythromycin, doxycycline,
azithromycin
8/3/2019 Legion Ella and Dental Water Lines
http://slidepdf.com/reader/full/legion-ella-and-dental-water-lines 11/28
Outbreak of legionellosis in
Wayne Co., Michigan in 1985
Early May of 1985
14 cases of pneumonia with high fever
occurred in 380 persons who attended a
church banquet at a hotel on April 27
3 cases fatal
Washings from the cooling coils of the A/C
units supplying the banquet hall positive for Legionella pneumophila
8/3/2019 Legion Ella and Dental Water Lines
http://slidepdf.com/reader/full/legion-ella-and-dental-water-lines 12/28
Outbreak in Ohio automotive
plant, 2001
March 12-15, 2001
4 cases of Legionnaires’ disease
Exposure to aerosol-producing devicesFinishing area
8/3/2019 Legion Ella and Dental Water Lines
http://slidepdf.com/reader/full/legion-ella-and-dental-water-lines 13/28
L. pneumophila and dentistry
Legionella associated with biofilms in
dental unit water lines (DUWLs)
Also Pseudomonas
DCWs shown to have an increased level of
antibodies to Legionella
DUWLs require treatment procedures to
control biofilm and reduce #s of mo’s
8/3/2019 Legion Ella and Dental Water Lines
http://slidepdf.com/reader/full/legion-ella-and-dental-water-lines 14/28
Dental Unit Waterlines (DUWL)
Bacteria in DUWL first noted in 1963 byDr. G.C. Blake
Large numbers of bacteria present in water
and aerosols associated with dental watersystems.
Biofilms form in DUWLs and can harbor a
variety of microorganisms.
Most of the microbes recovered from dental
water systems are gram-negative noncoliform
bacteria.
8/3/2019 Legion Ella and Dental Water Lines
http://slidepdf.com/reader/full/legion-ella-and-dental-water-lines 15/28
Safe Drinking Water Act
Sets standard for noncoliform bacteria in
drinking and recreational water at 500
CFU/ml.
DUWL contamination in untreated systems
often exceeds 1000 CFU/ml
Range of 10,000 to 100,000 CFU/ ml
commonplace ADA in 1996 established a goal for dental
water to contain no more than 200 CFU/ml
8/3/2019 Legion Ella and Dental Water Lines
http://slidepdf.com/reader/full/legion-ella-and-dental-water-lines 16/28
Why the high numbers in DUWL?
Surface colonization
Materials commonly used to deliver water to
dental handpieces, etc., provide excellent
substrates for colonization.Minerals in water, esp. calcium carbonate,
deposited.
Organic molecules attach & promote adhesion of
bacteria suspended in water Individual cells multiply to form microcolonies
Ultimately these coalesce and form a mature biofilm
8/3/2019 Legion Ella and Dental Water Lines
http://slidepdf.com/reader/full/legion-ella-and-dental-water-lines 17/28
Why the high numbers?
Laminar flow
Fluids moving through narrow-bore tubing
assume a hydrodynamic pattern known as
laminar flow.Frictional forces slow the movement of fluids at the
tubing surface, creating an environment conducive
to formation of biofilm
Flushing can eliminate suspended microbes butnot biofilm.
8/3/2019 Legion Ella and Dental Water Lines
http://slidepdf.com/reader/full/legion-ella-and-dental-water-lines 18/28
Why the high numbers? continued
Surface:volume ratio
As the diameter of a cylinder (waterline)
decreases, an increasingly larger surface area
becomes available for colonization.This is the biggest factor. Water moves from a
10 inch water main to a 0.5 inch pipe in the
dental office to dental water system tubing that
is 1/16 in. in diameter.
8/3/2019 Legion Ella and Dental Water Lines
http://slidepdf.com/reader/full/legion-ella-and-dental-water-lines 19/28
Water retraction
Older dental units designed to retract water
(to prevent water dripping from handpieces
and air/water syringes)
Could also retract oral fluids
Anti-retraction valves installed to prevent
retraction of oral fluids
8/3/2019 Legion Ella and Dental Water Lines
http://slidepdf.com/reader/full/legion-ella-and-dental-water-lines 20/28
What organisms present?
Biofilm is hospitable environment for fungi,
protozoa, and other organisms
Legionella pneumophila
Pseudomonas aeruginosa
Nontubercular Mycobacterium spp.
Mostly noncoliform gram-negatives but
coliforms have been isolated — especiallywith careless handling of bottles and feeder
tubes.
8/3/2019 Legion Ella and Dental Water Lines
http://slidepdf.com/reader/full/legion-ella-and-dental-water-lines 21/28
Improving the quality of dental
water
Waterline flushing
Efficacy not established as a stand alone tx
Does not remove biofilm but can remove
suspended organisms
Independent reservoirs
Allows control of water quality
Also best combined with chemical agents
8/3/2019 Legion Ella and Dental Water Lines
http://slidepdf.com/reader/full/legion-ella-and-dental-water-lines 22/28
Improving the quality of dental
water Chemical treatment – no ideal agent
Intermittent or continuous chemical release
Intermittent usually uses biocidal concentrations of
germicides that also remove biofilm
• Active agent purged prior to patient care
Continuous tx uses lower concentrations of
chemicals
Chlorine cpds (sodium hypochlorite)
Several dental unit manufacturers recommendweekly tx of DUWL with 1:10 dilution of
household bleach
8/3/2019 Legion Ella and Dental Water Lines
http://slidepdf.com/reader/full/legion-ella-and-dental-water-lines 23/28
Improving the quality of dental
water
Other chemical agents proposed or
evaluated:
Chlorhexidine gluconate
Hydrogen peroxide
Iodophors
Commercial mouthrinses
8/3/2019 Legion Ella and Dental Water Lines
http://slidepdf.com/reader/full/legion-ella-and-dental-water-lines 24/28
Improving the quality of dental
water Automated treatment devices
Ozone and silver germicide
Sterisil straw/cartridge contains a cation exchange
resin and silver (highest concentration 3 ppm) as a
germicide
Periodic treatment regimens
Several of these including DentaPure iodinated resin
cartridges which release 2-6 ppm free iodine into
treatment water to control biofilm
Water source controls - reservoirs
8/3/2019 Legion Ella and Dental Water Lines
http://slidepdf.com/reader/full/legion-ella-and-dental-water-lines 25/28
Improving the quality of dental
water
Filtration
Remove suspended bacteria but no effect on
biofilm formation in pretreatment areas of lines
DentaPure filter includes 0.22 m filter
8/3/2019 Legion Ella and Dental Water Lines
http://slidepdf.com/reader/full/legion-ella-and-dental-water-lines 26/28
Bottom Line – Infection control
dilemma
Potential source of infection of
immunocompromised patients
CDC recommendations:
Sterile irrigating solutions should be used when
surgical procedures involve cutting of bone.
All dental instruments that use water should be
run 20-30 seconds after each patient and for
several minutes before the start of each clinic
day.
8/3/2019 Legion Ella and Dental Water Lines
http://slidepdf.com/reader/full/legion-ella-and-dental-water-lines 27/28
UDMSD Procedures 1
Before first patient:
Fill water reservoir and attach to dental unit.
Turn on master switch, wait a few seconds for
system to pressurize.
Flush waterlines for at least 1 minute.
Between patients:
Flush lines 20-30 seconds.
8/3/2019 Legion Ella and Dental Water Lines
http://slidepdf.com/reader/full/legion-ella-and-dental-water-lines 28/28
UDMSD Procedures 2
At the end of the day:
Flush lines for 30 seconds.
Turn off master switch.
Remove all handpieces.
Remove and empty water bottle and place on
bracket tray.