1 Antibiotics and Antibiotic prophylaxis in Special Care Dentistry History of Antibiotics Antibiotic is a drug used to treat bacterial infections

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Antibiotics and Antibiotic prophylaxis in Special Care Dentistry

History of Antibiotics
Antibiotic is a drug used to treat bacterial infections. It is very powerful medicines that fight
certain infections and can save lives when used properly. Antibiotics can stop bacteria from
reproducing and can also destroys them. Normally before bacteria can multiply to cause any
symptoms, the body’s immune system will usually kill them. The white blood cells in our
system attack the harmful bacteria and, even if symptoms occur, our immune system can
usually cope and fight off the infection.
There are sometimes when it is all too much, and some help is needed; this is where antibiotics
are useful. Antibiotics will not have any effect on viral infections. Antibiotic was a substance
produced by a particular microorganism that selectively will inhibits the growth of another
microorganism. The synthetic antibiotics, they are the chemically related to natural antibiotics,
have since been produced that accomplish comparable tasks.
In year 1926, Alexander Fleming discovered penicillin, it is a substance produced by fungi that
appeared to be able to inhibit bacterial growth. In 1939, Edward Chain and Howard Florey
further did more studies about penicillin and later carried out trials of penicillin on humans
(with what were deemed fatal bacterial infections). Fleming, Florey and Chain shared the Nobel
Prize in 1945 for their work which ushered in the era of antibiotics.
Antibiotic prophylaxis refers to the prevention of infection complications using antimicrobial
therapy (most commonly antibiotics). Antibiotic prophylaxis is most commonly used prior to
surgery. Antibiotics can be effective in reducing the formation of infections. Patients selection
is important and a right antibiotic prophylaxis should be selected if the medical condition or
the surgical procedure is associated with a development of risk of infection or if the

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postoperative infection would cause a serious complication to the patient’s recovery and well-
being.
People with special needs sometimes need antibiotic prophylaxis due to any medical issues or
due to compromised immune system. The antibiotic prophylaxis has been used in dentistry for
patients at risk of infective endocarditis or prosthetic joint infection. The scientific rationale for
prophylaxis was to eliminate or reduce transient bacteraemia caused by invasive dental
procedures. Despite a long history of use and multiple guidelines for prophylaxis, there remains
uncertainty about its effectiveness. In the last 10 years, there have been significant changes to
the guidelines for antibiotic prophylaxis. These changes have been driven partly by global
concerns about antimicrobial resistance (WHO) and subsequent recommendations that any
prescription of antibiotics should be appropriate and judicious (Commonwealth of Australia
2016).
Another factor that has driven the changes has been the recognition that the incidence of
transient bacteraemia caused by oral hygiene procedures is often the same as the incidence
caused by many dental treatments for which prophylaxis has traditionally been given. Regular
toothbrushing and flossing pose a greater risk in relation to both infective endocarditis
(Lockhart PB et al 2008) and prosthetic joint infection (Berbari EF et al 2010) than episodic
dental treatment.

Toothbrushing (Silver JG 1977), flossing (Wank HA 1976), pulsating water irrigators (Berger
SA 1974) and interdental wood sticks (Lineberger LT 1973) can all produce bacteraemia.
Gingival inflammation has been significantly associated with an increased incidence of
bacteraemia caused by toothbrushing (Lockhart PB 2009). However, the incidence of
bacteraemia with flossing does not differ significantly between people with special needs with

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or without periodontal disease (Crasta K 2009). The incidence and magnitude of bacteraemia
caused by flossing are the same as that caused by deep scaling/root planning within the same
patients (Zhang W 2013) yet deep scaling/root planning is considered an ‘invasive dental
procedure’ that has traditionally required antibiotic prophylaxis.

Pharmacology, Chemistry and properties
Penicillin was the first antibiotic to be used clinically in 1941. It is a miracle that the least
toxic drug of its kind was the first to be discovered.
The penicillin nucleus consists of fused thiazolidine and ?-lactam rings to which side chains
are attached through an amide linkage (Fig 1)

Figure 1

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Mechanism of action Antibiotic
Different antibiotics have different modes of action, owing to the nature of their structure and
degree of affinity to certain target sites within bacterial cells.

Classifications of Antibiotics
There are several ways of classifying antibiotics but the most common classification schemes
are based on their molecular structures, mode of action and spectrum of activity (Calderon and
Sabundayo, 2007). Others include route of administration (injectable, oral and topical).
Antibiotics within the same structural class will generally show similar pattern of effectiveness,
toxicity and allergic potential side effects. Some common classes of antibiotics based on
chemical or molecular structures include Beta-lactams, Macrolides, Tetracyclines, Quinolones,
Aminoglycosides, Sulphonamides, Glycopeptides and Oxazolidinones (Adzitey 2015).

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Class Example
Beta Lactam
-Penicillin
-Cephalosporin
First Generation
Second Generation
Third Generation
Fourth Generation

Penicillin G, Penicillin V, Cloxacillin, ampicillin, amoxycillin

Cefazolin, Cephapirin
Cefuroxime, Cephalexin
Ceftriaxone, Cefdinir
Cefepime, Cefpirome
Beta Lactamase inhibitor Clavulanate, Salbactam
Aminoglycosides Gentamicin, Streptomycin, Neomycin
Tetracyclines Tetracyclines, Chlortetracyclines, Doxycyclines
Rifamycins Rifamycins
Macrolides Erythromycin, Azithromycin, Clarithromycin
Lincosamides Clindamycin, Lincomycin
Glycopeptides Vancomycin
Sulphonamides Sulfamethoxazole
Quinolones Norfloxacin, Ciprofloxacin
Others Metronidazole, Trimethoprin

Narrow Spectrum Antibiotics – Penicillin V, Clindamycin and Metronidazole
Broad Spectrum Antibiotics – Tetracycline, Chlorphenicol, Amoxycillin, Amoxycillin with
Clavulanic Acid, Cefazolin and Azithromycin
Bactericidal – Penicillin, Cephalosporins, Rifampin, Vancomycin, Cotrimaxazole,
Metronidazole, Ciprofloxacin

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Bacteriostatic – Sulfonamides, Tetracyclines, Erythromycin, Clindamycin
Gram +ve – Penicillin, Macrolides
Gram -ve – Steptromycin and others
Gram +ve and -ve – Ampicillin, Amoxycillin and Cephalosporin

Antibiotic resistance
Antibiotics are extremely important in medicine, but unfortunately bacteria are capable of
developing resistance to them. Antibiotic-resistant bacteria are bacteria that are not killed
effectively by antibiotics. When bacteria are exposed to the same medication over and over,
the bacteria change and are no longer affected by the drug.
There are several ways how bacteria become antibiotic-resistant. For example, they have an
internal mechanism of changing their structure so the antibiotic no longer works, they develop
ways to inactivate or neutralize the antibiotic. Also, bacteria can transfer the genes coding for
antibiotic resistance between them, making it possible for bacteria never exposed to an
antibiotic to acquire resistance. The problem of antibiotic resistance becomes more serious
when antibiotics are used to treat disorders for which they are ineffective.
Resistance to antibiotics represents a serious and growing problem, because some infectious
diseases are becoming hard to treat. Resistant bacteria do not respond to the antibiotics and
continue to cause the illness. Some resistant bacteria can be treated with more powerful
medicines, but some infections are difficult to cure even with novel drugs.

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Antibiotic Prophylaxis
Antibiotic prophylaxis refers to the prevention of infection complications by using
antimicrobial therapy or drugs (most commonly antibiotics). Antibiotic prophylaxis remains a
controversial topic in the dental community, even though new guidelines have been released
in recent years.
Amongst dentists there has been a ‘tradition’ to prescribe antibiotics as a prophylactic weapon
to prevent post-surgical infections or distant-site infections.
Antibiotics are routinely prescribed in dental practice for either prophylactic or therapeutic use.
Prophylactic antibiotics are prescribed to prevent diseases caused by the introduction of
members of the oral flora to distant sites or to a local, compromised, site in a host at risk (Dajani
AS 1997). In most cases, prophylaxis is used to prevent endocarditis, whereas therapeutic
antibiotics are prescribed mostly to treat diseases of the hard and soft tissues in the oral cavity
after local debridement has failed (Fine DH 1998).
Dentists’ use of antibiotics is characterised by a number of particularities. In effect, antibiotic
prescription is empirical; the clinician does not know what microorganism is responsible for
the infection because cultures are not commonly grown from the patient’s pus or exudate. Based
on clinical and bacterial epidemiological data, the types of microorganisms responsible for the
infectious process are suspected, and treatment is decided on a presumptive basis, fundamental
on probabilistic reasoning (Vallano A 2006).

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Prosthetic Replacement
Prosthetic replacement of large joints such as the hip, knee, elbow and the shoulder are a
common and highly successful orthopaedic surgical procedure. Mechanical failure (loosening
or fracture) is the most common complication affecting prosthetic joints followed by joint
infection (Uckay I 2008). The infection at the joint can occur as early as less than 3 months
immediately after the surgery, or later even up to 24 months after the joint replacement surgery
(Uckay I 2008). Infection to the replaced prosthetic joint can be serious and can leads to loss
of the prosthetic joint and can cause serious morbidity for the patient. When there is late
prosthetic joint infection due to streptococcal is more manageable with debridement and a
course of antibiotic then with infection by staphylococcal (Uckay I 2008). It is said that risk of
oral organisms from dental procedure induced bacteraemia, infection a prosthetic joint
(Jacobsen JJ 1980). The prophylactic antibiotics before invasive dental care have been
recommended to reduce the risk of a prosthetic joint infection occurring. Joint replacement is
becoming more common in people with special needs. Up until 2012, antibiotics were
recommended for two years after surgery or for a lifetime.

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In 2012, a panel of experts representing the American Academy of Orthopaedic Surgeons
(AAOS) and the American Dental Association (ADA) (the 2012 Panel) published a systematic
review and accompanying clinical practice guideline (CPG) entitled “Prevention of
Orthopaedic Implant Infection in Patients Undergoing Dental Procedures: Evidence-based
Guideline and Evidence Report” (Watters W 2013). The 2014 Panel considered the direct
evidence linking a Prosthetic Joint Infection with a dental procedure but did not re-evaluate
intermediate outcomes, including bacteraemia (Lockhart PB 2008) from manipulation of oral
mucosa. In their systematic review (ADA 2012) the 2012 Panel identified 1 study that provided
direct evidence about dental procedures as risk factors for developing prosthetic hip and knee
implant infections. The authors reviewed and abstracted information from dental records to
determine the association between the dental procedures (exposure) and hip and knee
infections. Exposure was measured within the previous 6 months and 2 years before hospital
admission and classified as low-risk dental procedures (fluoride treatment, restorative
dentistry, and endodontic treatment) and high-risk dental procedures (periodontal treatment,
extractions, treatment of a dental abscess, oral surgery, and dental hygiene), as defined by
Berbari and colleagues (Berbari EF 2010). Comprehensive reviews of the literature have failed
to demonstrate substantive credible evidence of haematogenous infection of prosthetic joints
by oral organisms following dental procedures.
Effectiveness of prophylactic antibiotics prior to dental procedures may reduce the risk and
intensity of any bacteraemia. However, there is no evidence that antibiotic prophylaxis reduces
or eliminates the risk of late prosthetic joint infection.

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Consideration regarding use of prophylactic antibiotic
The following considerations contribute to the argument against antibiotic prophylaxis.
Antibiotic resistance. There is a long-standing and increasing concern that repeated exposure
to antibiotics is a risk factor for the development of resistant bacterial species (for example,
penicillin-resistant streptococci)
Adverse drug reactions. Although there are no data regarding the risk of developing a drug
reaction from 1 dose of amoxicillin prescribed to prevent a distant site infection such as
Prosthetic Joint Infection, older data involving prophylaxis regimens that included
intramuscular injections and multiple oral doses suggest that more people who are given
antibiotic prophylaxis would experience drug reactions from penicillin-type drugs, some of
which may be fatal, than would be prevented from developing Prosthetic Joint Infection. Of all
allergens, penicillin is the most frequent medication-related cause of anaphylaxis in humans.
Other potential antibiotic-associated adverse reactions include nausea, vomiting, and diarrhoea.
There also is an increased risk of experiencing adverse reactions with increasing patient age.
Prolonged treatment with antibiotics is associated with infections secondary to changes in the
gastrointestinal microbial flora, which includes that involved in the development of oral thrush.
For example, Clostridium difficile infection potentially can cause pseudomembranous colitis
after patients are prescribed antibiotics to treat other infections (Bartlett JG 2006). Recognizing
that a single dose of antibiotics for prophylaxis of Prosthetic Joint Infection is unlikely to cause
an infection, comprehensive dental care for people with special needs often involves multiple
appointments over a short period. In addition, people with special needs may have taken
antibiotics for other medical conditions in the past, increasing their risk of experiencing
changes in the gastrointestinal flora. Investigators have identified clindamycin, cephalosporins,
and fluoroquinolones as the inducing agent (Bartlett JG 2006).

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CONCLUSIONS
Evidence fails to demonstrate an association between dental procedures and Prosthetic Joint
Infection or any effectiveness for antibiotic prophylaxis. Given this information in conjunction
with the potential harm from antibiotic use, using antibiotics before dental procedures is not
recommended to prevent Prosthetic Joint Infection. Additional case control studies are needed
to increase the level of certainty in the evidence to a level higher than moderate.
In patients with a history of complications associated with their joint replacement surgery who
are undergoing dental procedures that include gingival manipulation or mucosal incision,
prophylactic antibiotics should only be considered after consultation with the patient and
orthopaedic surgeon (ADA 2017).
The 2015 ADA clinical practice guideline states that “In general, for patients with prosthetic
joint implants, prophylactic antibiotics are NOT recommended prior to dental procedures to
prevent prosthetic joint infection” (Sollecito TP 2015).

Management of people with special needs with prosthetic joints undergoing dental
procedures
Clinical Recommendation:
In general, for people with special needs with prosthetic joint implants, prophylactic antibiotics
are not recommended prior to dental procedures to prevent prosthetic joint infection. For
patients with a history of complications associated with their joint replacement surgery who
are undergoing dental procedures that include gingival manipulation or mucosal incision,
prophylactic antibiotics should only be considered after consultation with the patient and
orthopaedic surgeon. In cases where antibiotics are deemed necessary, it is most appropriate

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that the orthopaedic surgeon recommend the appropriate antibiotic regimen and when
reasonable write the prescription (Sollecito TP 2015). To assess a patient’s medical status, a
complete health history is always recommended when making final decisions regarding the
need for antibiotic prophylaxis.

Clinical Reasoning for the Recommendation:
• There is evidence that dental procedures are not associated with prosthetic joint implant
infections.
• There is evidence that antibiotics provided before oral care do not prevent prosthetic joint
implant infections.
• There are potential harms of antibiotics including risk for anaphylaxis, antibiotic resistance,
and opportunistic infections like Clostridium difficile.
• The benefits of antibiotic prophylaxis may not exceed the harms for most patients.
• The individual patient’s circumstances and preferences should be considered when deciding
whether to prescribe prophylactic antibiotics prior to dental procedures (ADA 2017).
However, the New Zealand Orthopaedic Association has adopted the American Dental
Association / American Association of Orthopaedic Surgeons guidelines for antimicrobial
prophylaxis for patients with prosthetic hip and /or knee joints undergoing invasive dental
procedures within 2 years of the joint prosthesis being placed. After 2 years antimicrobial
prophylaxis is not required unless the patient has a history of the following:
• Inflammatory arthropathy including Rheumatoid Arthritis and Systemic Lupus
Erythematous
• Malnourishment or very elderly

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• Haemophilia
• Immunosuppression including medication induced, diabetes or radiation
• Previous joint infection
The standard regimen of pre-operative 2g amoxicillin orally one hour prior to procedure is
recommended or clindamycin 600mg orally one hour prior to procedure (School of
Dentistry memorandum 2010).

Infective Endocarditis

Endocarditis is an inflammation of the endocardium, the membrane lining the chambers of the
heart and covering the cusps of the heart valves (Pierce D 2012). More commonly, endocarditis
refers to infection of the heart valves by various microorganisms. Although it typically affects
native valves, it also may involve nonvalvular areas or implanted mechanical devices (e.g.,
mechanical heart valves). Bacteria primarily cause endocarditis, but fungi and other atypical
microorganisms can lead to the disease. Hence, the more encompassing term infective
endocarditis is preferred (Pierce D 2012). Endocarditis is often referred to as acute or subacute
depending on the pace and severity of the clinical presentation. The acute, fulminating form is

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associated with high fevers and systemic toxicity. Virulent bacteria, such as Staphylococcus
aureus, frequently cause this syndrome, and if untreated, death may occur within days to weeks.
On the other hand, subacute infective endocarditis is more indolent, and it is caused by less
invasive organisms, such as viridans streptococci, usually occurring in pre-existing valvular
heart disease. Although infective endocarditis is often referred to as acute or subacute, it is best
classified based on the etiologic organism, the anatomic site of infection, and pathogenic risk
factors (Qui Y 2011). Infection also may follow surgical insertion of a prosthetic heart valve,
resulting in prosthetic valve endocarditis (PVE), or insertion of a cardiac implantable electronic
device, resulting in cardiac device infective endocarditis (CDIE) (Nishimura RA 2008).

Pathophysiology
The development of infective endocarditis via hematogenous spread, the most common route,
requires the sequential occurrence of several factors.
i) The endothelial surface of the heart is damaged. This injury occurs with turbulent
blood flow associated with the valvular lesions previously described.
ii) Platelet and fibrin deposition occurs on the abnormal epithelial surface. These
platelet–fibrin deposits are referred to as nonbacterial thrombotic endocarditis.
iii) Bacteraemia gives organisms access to and results in colonization of the endocardial
surface. Bacteraemia is the result of trauma to a mucosal surface with a high
concentration of resident bacteria, such as the oral cavity and GI tract. Transient
bacteraemia commonly follows certain dental, GI, urologic, and gynaecologic
procedures. Staphylococci, viridans streptococci, and enterococci are most likely to
adhere to nonbacterial thrombotic endocarditis, probably because of production of
specific adherence factors, such as dextran by some oral streptococci and

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glycocalyx for staphylococci. Gram-negative bacteria rarely adhere to heart valves
and are uncommon causes of infective endocarditis.
iv) After colonization of the endothelial surface, a “vegetation” of fibrin, platelets, and
bacteria forms. The protective cover of fibrin and platelets allows unimpeded
bacterial growth to a very high concentrations.

Prevention
Antimicrobial prophylaxis is used as an attempt to prevent infective endocarditis for patients
who are at the highest risk (Nishimura RA 2008).
The use of antimicrobials for this purpose requires consideration of
(a) cardiac conditions associated with endocarditis
(b) procedures causing bacteraemia
(c) organisms likely to cause endocarditis
(d) pharmacokinetics, spectrum, cost, adverse effects, and ease of administration of available
antimicrobial agents.
The objective of prophylaxis is to diminish the likelihood of infective endocarditis in high-risk
individuals from procedures that result in bacteraemia. Although there are no prospective,
controlled human trials demonstrating that prophylaxis in high-risk individuals protects against
the development of endocarditis during bacteraemia-induced procedures, animal studies
suggest possible benefit (Wilson W 2008). Many causes of infective endocarditis, however,
appear not to be secondary to an invasive procedure. Bacteraemia as a consequence of daily
activities may, in fact, be the major culprit, and the value of antibiotic prophylaxis before
bacteraemia-causing procedures has been questioned (Roberts GJ 1999). Retrospective human

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studies, though, support that a reduction of endocarditis occurs for select patients following
dental surgery where prophylaxis is employed (Wilson W 2008). The common practice of
using antimicrobial therapy in this setting remains controversial. The mechanism of a beneficial
effect in humans is unclear, but antibiotics may decrease the number of bacteria at the surgical
site, kill bacteria after they are introduced into the blood, and prevent adhesion of bacteria to
the valve. Prophylaxis does not reduce the frequency of bacteraemia immediately following
tooth extraction as compared with a control group, suggesting that a reduction in adhesion or
effects after the bacteria adhere to the endocardium are more likely mechanisms (Hall G 1993).
Regardless of the controversy about whether prophylactic antibiotics should be used, infective
endocarditis prophylaxis is recommended in select situations, specifically dental procedures,
in those with underlying high-risk cardiac conditions. The AHA released updated guidelines
that better define who should and should not receive infective endocarditis prophylaxis (Wilson
W 2007). This update is important as data show overuse of infective endocarditis prophylaxis
occurs in low-risk patients and underuse occurs in those at greater risk (Seto TB 2000).
Some studies shows only a small number of cases of infective endocarditis might be prevented
with antibiotic prophylaxis for dental procedures, even if 100% effective, infective
endocarditis prophylaxis for dental procedures should be recommended only for patients with
underlying cardiac conditions associated with the highest risk, for those with high-risk
underlying cardiac conditions, prophylaxis is recommended for all dental procedures involving
manipulation of gingival tissue or the periapical region of teeth or perforation of the oral
mucosa, prophylaxis is not recommended based solely on an increased lifetime risk of
acquisition of infective endocarditis, and administration of antibiotics solely to prevent
endocarditis is not recommended for patients who undergo a genitourinary or GI tract
procedure. To determine whether a patient should receive prophylactic antibiotics, one needs
to assess the patient’s risk and whether he or she is undergoing a procedure resulting in

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bacteraemia. When antibiotic prophylaxis is appropriate, a single 2 g dose of amoxicillin is
recommended for adult patients at risk, given 30 to 60 minutes before undergoing procedures
associated with bacteraemia. Because the duration of antimicrobial prophylaxis appears to be
relatively short, guidelines do not advocate a second oral dose of amoxicillin, which was
recommended previously. Alternative prophylaxis regimens for patients allergic to penicillin
or those unable to take oral medications are also provided.

Clinical Controversy
The common practice of administering antibiotics to high-risk individuals before a
bacteraemia-causing procedure is controversial. Despite limited data supporting this approach
and the fact that 100% compliance with AHA preventative guidelines would have only a
modest benefit, the use of single-dose antibiotics for the prevention of endocarditis remains a
standard of care.

Dental Procedures and Infective Endocarditis
In the past, patients with nearly every type of congenital heart defect needed to receive
antibiotics one hour before dental procedures or operations on the mouth, throat,
gastrointestinal genital, or urinary tract. However, in 2007 the American Heart Association
simplified its recommendations. Today, antibiotics before dental procedures are only
recommended for patients with the highest risk of IE, those who have:
• A prosthetic heart valve or who have had a heart valve repaired with prosthetic material.
• A history of endocarditis.
• A heart transplant with abnormal heart valve function

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• Certain congenital heart defects including:
-Cyanotic congenital heart disease (birth defects with oxygen levels lower than
normal), that has not been fully repaired, including children who have had a surgical
shunts and conduits.
-A congenital heart defect that’s been completely repaired with prosthetic material or a
device for the first six months after the repair procedure.
-Repaired congenital heart disease with residual defects, such as persisting leaks or
abnormal flow at or adjacent to a prosthetic patch or prosthetic device (AHA)

Numerous scientific evidence concluded that the risk of adverse reactions to antibiotics
generally outweighs the benefits of prophylaxis for many patients who would have been
considered eligible for prophylaxis in previous guidelines. Concern about the development of
drug-resistant bacteria also was a factor for the simplified guidelines.
The 2014 ADA/ACC (American College of Cardiology) guidelines add that optimal oral health
is maintained through regular professional dental care and the use of appropriate dental
products, such as manual, powered, and ultrasonic toothbrushes, dental floss, and other plaque-
removal devices (Nishimura RA 2014)

Prophylaxis guidelines
Since the 1950s there has been a progressive reduction in the use of antibiotics in the prevention
of endocarditis following dental therapy. Different countries have made different

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recommendations. The changes in the USA in 2007 limited prophylaxis to patients with
conditions including prosthetic cardiac valves or valves repaired with prosthetic material,
previous infective endocarditis, unrepaired and repaired congenital cardiac defects and cardiac
transplants with subsequent valvopathy. Patients with mitral valve prolapse, even with severe
regurgitation, no longer required prophylaxis (Wilson W 2007)

Evolution of guidelines for endocarditis prophylaxis
Year Organisation Recommendation for patients without
penicillin hypersensitivity
1955 American Heart Association Intramuscular benzylpenicillin for all patients
at risk
1982 British Society for Antimicrobial
Chemotherapy
Oral amoxicillin, 3 g one hour before treatment,
1.5 g six hours after treatment
1997 American Heart Association Oral amoxicillin, 2 g one hour before treatment
2007 American Heart Association Prophylaxis limited to high-risk patients
2008 National Institute for Health and
Clinical Excellence (UK)
No antibiotic prophylaxis

In 2008 the abolition of antibiotic prophylaxis for all patients in the UK was a radical change
in practice. It resulted in considerable controversy including claims from UK cardiologists that
patient safety would be compromised (NICE 2016). Following these changes in the USA and

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UK, revised infective endocarditis prophylaxis guidelines were soon introduced in Australia,
New Zealand and Europe. The reason for differing opinions on prophylaxis is the lack of
evidence on which to base conclusions. Cochrane review found no randomised controlled trials
that had studied the efficacy of antibiotic prophylaxis for preventing infective endocarditis due
to dental treatment (Glenny AM 2013). This review identified only one case-control study
which found no significant effect of penicillin prophylaxis. The review therefore concluded
that there was no evidence that antibiotic prophylaxis was effective or ineffective in preventing
infective endocarditis in at-risk individuals undergoing invasive dental procedures (Glenny
AM 2013).

Current guidelines
Expert committees around the world have recently issued updated guidelines. In the UK, NICE
concluded that there was insufficient evidence to change its existing guidelines and it continues
to recommend no routine antibiotic prophylaxis for dental treatment for patients at risk of
infective endocarditis (NICE 2016). In contrast, expert committees in Europe, the USA and
Australia, despite assessing the same evidence as NICE, continue to recommend antibiotic
prophylaxis in selected patients.
From the New Zealand Heart Foundation Guidelines 2008, the number of cardiac conditions
for which prophylaxis is recommended are
• Prosthetic heart valves (bio or mechanical)
• Rheumatic valvular heart disease
• Previous endocarditis
• Unrepaired cyanotic congenital heart disease (including palliative shunts and conduits)

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• Surgical or catheter repair of congenital heart disease within 6 months of repair
procedure.
This condition has been selected because of a high lifetime risk of endocarditis and a high
risk of mortality or major morbidity resulting from bacterial endocarditis.
The main difference from other national recommendations is the retention of rheumatic
heart disease in the list of conditions requiring prophylaxis. This shows that high lifetime
risk of endocarditis in the populations and the potential for significant adverse outcome
after endocarditis. Rheumatic heart disease remains a major cause of morbidity and
mortality in New Zealand and the recommendations take into account this difference from
other developed countries. Although it is possible that the risk of endocarditis may differ
with the severity of rheumatic valvular involvement, there is no clear evidence to this effect
and prophylaxis is therefore recommended regardless of severity. Prophylaxis is not
recommended for those who have had previous rheumatic fever without cardiac
involvement.
The New Zealand Heart Foundation highlights the imperative that at-risk patients should
remain free of dental disease. This requires emphasis on improved access to dental care and
improved oral health in patients with underlying cardiac risk factors for infective
endocarditis, rather than sole focus on dental procedures and antibacterial prophylaxis.
Optimal oral health is maintained through regular professional care and the use of
appropriate products such as manual and powered toothbrush, floss and other plaque
control devices such as antibacterial mouthwashes. Patient need to be strongly advised to
comply with a continuing oral and dental care regime.
Antibiotic prophylaxis needed to be prescribed for dental procedures:
• Removal of impacted teeth and unerupted teeth

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• Treatment of all teeth with periapical disease by endodontic debridement and root
filling or apical surgery or extraction
• Removal of all carious teeth that cannot be restored
• Treatment of other abnormalities such as cysts or intra-bony lesions associated with
the dentition and related structure
• Treatment of oral ulcers including those caused by ill fitting or irritating dental
appliances
• Treatment of inflammatory periodontal disease
• Oral hygiene instructions for the patient to ensure maintenance of ideal oral health
Under the New Zealand Heart Foundation guidelines, dental procedures (plus
tonsillectomy/ adenoidectomy) for which endocarditis prophylaxis is recommended.

The dental procedure where the antibiotic prophylaxis is not indicated:
• Routine anaesthetic injections through non infected tissue
• Taking dental radiographs
• Placement or removable prosthodontic or orthodontic appliances
• Adjustment of orthodontic appliances
• Placement of orthodontic brackets
• Shedding of deciduous teeth
• Bleeding from trauma to the lips or oral mucosa
Both bactericidal (e.g. amoxycillin) and bacteriostatic or non-killing regimens (e.g.
clindamycin or clarithromycin) are very effective so long as the antibacterial agent is present

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in the blood stream for long enough. This can be achieved with a single dose of the agents,
provided in the correct dosage is given.
The antibiotic prophylactic regime: (New Zealand Heart Foundation 2008)
Amoxycillin 2g (child: 50mg/kg up to 2g), administered
• Orally, 1 hour before the procedure, or
• IV, just before the procedure, or
• IM, 30 minutes before the procedure.
Administer parenterally if unable to take medication orally; administer IV if IV
access is readily available.
For penicillin allergy or if a penicillin or cephalosporin-group antibiotic is taken
more than once in the previous month
(including those on long-term penicillin prophylaxis for rheumatic fever):
Clindamycin 600mg (child: 15mg/kg up to 600mg), administered
• Orally, 1 hour before the procedure, or
• IV, over at least 20 minutes, just before the procedure, or
• IM, 30 minutes before the procedure.
Or
Clarithromycin 500mg (child: 15mg/kg up to 500mg) orally, 1 hour before the
procedure.
Clindamycin is not available in syrup form in New Zealand.
Potential interactions between clarithromycin and other medications

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If the antibacterial agent is inadvertently not administered before the procedure, it may be
administered up to 2 hours after the procedure.

Patients with compromised immunity
Patients with a compromised immune system may not be able to tolerate a transient
bacteraemia following invasive dental procedures. These non-cardiac factors can place a
patient with compromised immunity at risk for distant-site infection from a dental procedure.
This category includes, but is not limited to, patients with the following medical conditions:
(Lockhart PB 2007)
1. Immunosuppression secondary to:
a. human immunodeficiency virus (HIV)
b. severe combined immunodeficiency (SCIDS)
c. neutropenia
d. cancer chemotherapy
e. hematopoietic stem cell or solid organ transplantation.
2. Head and neck radiotherapy.
3. Autoimmune disease (e.g., juvenile arthritis, systemic lupus erythematosus).
4. Sickle cell anaemia.
5. Status post splenectomy.
6. Chronic steroid usage.
7. Diabetes.

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8. Bisphosphonate therapy.
Consultation with the physician is recommended for management of patients with a
compromised immune system. Discussion of antibiotic prophylaxis for patients undergoing
chemotherapy, irradiation, and hematopoietic cell transplantation appears in a separate AAPD
guideline.

Patients with shunts, indwelling vascular catheters, or medical devices.
The AHA recommends that antibiotic prophylaxis for nonvalvular devices, including
indwelling vascular catheters (e.g., central lines) and cardiovascular implantable electronic
devices (CIED), is indicated only at the time of placement of these devices in order to prevent
surgical site infection (Lockhart PB 2007). The AHA found no convincing evidence that
microorganisms associated with dental procedures cause infection of CIED and nonvalvular
devices at any time after implantation (Lockhart PB 2007). The infections occurring after
device implantation most often are caused by Staphylococcus aureus and coagulase negative
staphylococci or other microorganisms that are non-oral in origin but are associated with
surgical implantation or other active infections. The AHA further states that
immunosuppression is not an independent risk factor for nonvalvular device infections,
immunocompromised hosts who have those devices should receive antibiotic prophylaxis as
advocated for immunocompetent hosts (Lockhart PB 2007). Consultation with the physician is
recommended for management of patients with nonvalvular devices. Ventriculoatrial (VA),
ventriculocardiac (VC), or ventriculovenus (VV) shunts for hydrocephalus are at risk of
bacteraemia-induced infections due to their vascular access (Lockhart PB 2007). In contrast,
ventriculoperitoneal (VP) shunts do not involve any vascular structures and, consequently, do

26

not require antibiotic prophylaxis (Lockhart PB 2007). Consultation with the physician is
recommended for management of patients with vascular shunts.

STENTS

A stent is a tiny wire mesh tube that helps keep the coronary arteries open, which in turn reduces
the chance of a heart attack. It is placed with the use of a balloon catheter that expands and
locks the wire mesh. The stent is left permanently. Antibiotic prophylaxis for dental procedures
is NOT recommended for patients with coronary artery stents (Wilson W 2007)
Primary prophylaxis for stent placement is not routinely advocated because the overall
infection risk is extremely low. In addition, dental, respiratory, gastrointestinal, or
genitourinary procedures have not been implicated as causes of bacteraemia that have
accounted for stent infections (Baddour LM 2003). However, the latest AHA guidelines
recommend antimicrobial cover for cardiac stents within one month of placement. After 28
days it is assumed that epithelisation of the stent has occurred and that antimicrobial cover is
no longer required.

27

Medication Related Osteonecrosis of Jaw (MRONJ)
Antibiotic prophylaxis and or antibiotic therapy protocols have been established as an effective
therapeutic tool in the prevention or conservative management of certain diseases. One such
disease is chemotherapy associated osteonecrosis of the jaw caused by bisphosphonates (or
other drugs), described by Marx in 2003 as an exposure of necrotic bone with more than eight
weeks of evolution, associated with bisphosphonates and no prior radiation therapy. These
lesions can progress and become infected or even suffer other complications, making them
difficult to manage and with a wide range of therapies providing inconsistent results.
Antibiotic prophylaxis can be beneficial in avoiding the onset of medication related
osteonecrosis of jaw (MRONJ) in patients who are set to undergo oral surgery (extraction) and
are currently being treated with oral and intravenous bisphosphonates. If MRONJ has already
developed and is under control, antibiotic treatment prophylaxis can prevent its recurrence.
Moreover, antibiotic prophylaxis can help reduce the symptoms of osteonecrosis of the jaw,
aiding in a conservative management regimen. However, despite the many studies found in the
literature, there is no consensus on which the most used antibiotic and its dosage is.
In conclusion, it is clear that in patients being treated with oral and intravenous bisphosphonates
who have not had prior chemotherapy associated osteonecrosis of the jaw, the use of antibiotic
prophylaxis prior to oral surgery is an important tool in avoiding osteonecrosis and in
promoting proper healing of the affected area. If a patient previously had chemotherapy
associated osteonecrosis after a tooth extraction, antibiotic prophylaxis will be indicated to
prevent the recurrence of osteonecrosis and to promote healing of the extraction site. If
chemotherapy associated osteonecrosis is already present, antibiotic therapy is a vital part of
conservative management to reduce the symptomatology of MRONJ and keep it from
worsening.

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Drug Interactions
When a patient takes two or more drugs concurrently, an effect other than what is achieved
with each single drug may result. Drug–drug interactions may be pharmacokinetic or
pharmacodynamic. Pharmacokinetic interactions relate to drug absorption, distribution,
metabolism, and excretion. Pharmacodynamic interactions refer to the relationship between
drug concentration at the site of action and the resulting effect on the body. The presence of
food in the stomach can increase or decrease drug absorption. Prescribed medicines and
recreational drugs or natural products may interact, though these are often poorly researched.

29

30

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