The normal bacterial flora of the oral cavity includes hundreds of microorganism species that live in the mouth, with the most common being streptococci which can cause infections like dental caries and periodontitis if they enter the bloodstream through procedures like tooth extractions; one such infection is subacute bacterial endocarditis where oral bacteria colonize on heart valves, so antibiotic prophylaxis is recommended for at-risk patients before certain dental work to prevent this.

2. The Normal Bacterial Flora of oral cavity
Flora of the mouth refers to the bacteria and other
microorganisms that can and do live inside the
mouth. There are literally hundreds of different
species of microorganisms that live inside the
mouth. Most are relatively harmless. Others have
been implicated in a variety of health disorders.
The two most common disease states that are
attributed primarily to oral flora are dental caries
(cavities) and periodontitis (gum disease). Other
less common conditions are oral yeast infections
and oral herpes.

3. The presence of nutrients, epithelial debris, and secretions makes the
mouth a favorable habitat for a great variety of bacteria.
The normal flora occupy available colonization sites which makes it
more difficult for other microorganisms (nonindigenous species) to
become established. Also, the oral flora contribute to host nutrition
through the synthesis of vitamins, and they contribute to immunity by
inducing low levels of circulating and secretory antibodies that may
cross react with pathogens. Finally, the oral bacteria exert microbial
antagonism against nonindigenous species by production of inhibitory
substances such as fatty acids, peroxides and bacteriocins.

4. Oral flora are able to live and thrive in the mouth because the
conditions are nearly ideal. The mouth is warm, dark, moist, and
usually provides a good food supply to the flora.
Most microorganisms live in the periodontal sulcus between the teeth
and gums. Others can hide in the small pits and fissures of the teeth
where it is difficult to remove them with a toothbrush.
If oral streptococci are introduced into wounds created by dental
manipulation or treatment, they may adhere to heart valves and initiate
subacute bacterial endocarditis.

5. Subacute Bacterial Endocarditis
Subacute Bacterial Endocarditis (SBE) is a bacterial
infection that produces growths on the endocardium (the
cells lining the inside of the heart). Subacute bacteria
l endocarditis usually (but not always) is caused by a
viridans streptococci (a type of bacteria); it occurs on
damaged valves, and, if untreated, can become fatal
within six weeks to a year.

6. Causes and Risk Factors of Subacute Bacterial
Endocarditis
Subacute bacterial endocarditis (SBE) is usually caused by
streptococcal species (especially viridans streptococci),
and less often by staphylococci.
SBE often develops on abnormal valves after
asymptomatic bacteremias (bacteria traveling through the
bloodstream) from infected gums, or from gastrointestinal,
urinary, or pelvic procedures.

7. Symptoms of Subacute Bacterial Endocarditis
Most patients present with a fever that lasts several days
to 2 weeks. Nonspecific symptoms are common. Cough,
shortness of breath, joint pain, diarrhea, and abdominal or
flank pain may be present,anaemiaand blood in urine.
About 90 percent of patients will have heart murmurs, but
murmurs may be absent in patients with right-sided heart
infections. A changing murmur is common only in acute
endocarditis.

8. Diagnosis of Subacute Bacterial Endocarditis
Endocarditis is suspected in a patient with a heart
murmur and unexplained fever for at least one week, and
in an intravenous drug abuser with a fever, even in the
absence of hearing a murmur.
A definitive clinical diagnosis requires blood cultures that
grow bacteria. Echocardiography (ultrasound study of the
heart) may visualize vegetations (growths) on heart valves.

9. Treatment of Subacute Bacterial Endocarditis
Cure of endocarditis requires eradication of all microorganisms from
the vegetation(s), usually on the heart valve.
Bacterial endocarditis almost always requires hospitalization for
antibiotic therapy, generally given intravenously, at least at the
outset. Most patients respond rapidly to appropriate antibiotic
therapy, with over 70 percent of patients becoming afebrile (without a
fever) within one week. Occasionally, therapy with oral antibiotics at
home will be successful.
Antibiotic therapy must usually continue for at least a month.
In unusual cases, surgery may be necessary to repair or replace a
damaged heart valve.

10. Patients are categorized as:
-High risk patients for bacterial endocarditis
-Moderate risk patients for bacterial -endocarditis
-Negligible risk patients for bacterial endocarditis

11. Patients at high risk for bacterial
endocarditis
• Prosthetic cardiac valves, including
bioprosthetic and homograft valves
• Previous bacterial endocarditis
• Complex cyanotic congenital heart
disease (e.g., Tetralogy of Fallot)
• Surgically constructed systematic
pulmonary shunts or conduits

12. Patients at moderate risk for
bacterial endocarditis
• Acquired valvular dysfunction (e.g.,
rheumatic heart disease)
• Hypertrophic cardiomyopathy
• Mitral valve prolapse with valvular
regurgitation and/or thickened leaflets
• Most other congenital cardiac
malformations (other than those cited as
high or low risk)

13. Patients at negligible risk for
bacterial endocarditis
• Mitral Valve Prolapse without valvar regurgitation
• Rheumatic Heart Disease or Kawasaki Disease without
valvar dysfunction
• Physiologic, functional or innocent heart murmurs
• Previous coronary artery bypass surgery
• Cardiac pacemakers or defibrillators
• Isolated secundum atrial septal defect
• Surgical repair of atrial septal defect, ventricular septal
defect, or patent ductus arteriosus (without
• residua beyond 6 months)

14. Complications
If bacterial endocarditis is not adequately treated, it can be
fatal. This is dependent on the infecting organism. Even
when treated, further damage to a heart valve may can to
heart failure. In addition, blood clots can form and travel
throughout the bloodstream to the brain or lungs.

15. In Adults, the new antibiotic regime recommended for the
prevention of bacterial endocarditis is: Amoxycillin: 2.0
grams, 1 hour prior to the procedure (Four 500 mg tablets)
For those patients allergic to penicillin, Clindamycin: 600
mg, 1 hour to the procedure (Four 150 mg tablets)
The guidelines for Children are: Amoxycillin: 50 mg/kg, 1
hour prior to the procedure.
For those patients allergic to penicillin, Clindamycin: 20
mg/kg, 1 hour prior to the procedure.

16. - Cannot use oral medications
Ampicillin
Adults, 2.0 g IM or IV ;
Children, 50 mg/kg IM or IV
within 30 minutes before
procedure.
Cephalexin or cefadroxil
Adults, 2.0 g;
Children, 50 mg/kg orally
one hour before procedure
- Allergic to penicillin
Azithromycin or
Clarithromycin
Adults, 500 mg;
Children, 15 mg/kg orally
one hour before procedure

17. Clindamycin Adults, 600 mg;
Children, 15 mg/kg IV one
hour before procedure
- Allergic to penicillin and
unable to take oral
medications
Cefazolin Adults, 1.0 g;
Children, 25 mg/kg IM or IV
within 30 minutes before
procedure.
†Cephalosporins should not be used in patients with immediate-
type hypersensitivity
reaction (urticaria, angioedeman or anaphylaxis) to penicillins.
‡Total children’s dose should not exceed adult dose.
§ IM: intramuscular; IV: intravenous

18. Patients at risk requiring antibiotic prophylaxis who are
already receiving an antibiotic for a preexisting condition
should receive an antibiotic for prophylaxis from a different
classification.
For example, a patient at risk already receiving penicillin for
some other condition should receive another antibiotic for
prophylaxis, such as clindamycin.

19. Antibiotic prophylaxis is recommended for patients with total joint
replacements that are considered at increased risk of hematogenous
total joint infection.
They are the following:
• Previous history of prosthetic joint
infection
• Immunosuppressed/immunocompromi
sed patients
• Inflammatory arthorpathies:
Rheumatoid arthritis
• Disease-, drug- or radiation-induced
immunosuppression
• Insulin dependent diabetics; Type 1
• Malnourished patients
• Hemophiliacs

20. Antibiotic prophylaxis is not recommended for patients with pins,
plates, and screws.
In the past, administration of antibiotics prior to dental work was only
recommended during the first two years after surgery. Because of
concerns about the severity of infection of a joint replacement, the
American Academy of Orthopaedic Surgeons now recommends that
antibiotics be given before an invasive dental procedure no matter how
long it has been since the joint replacement procedure.

21. The connection between subacute bacterial
endocarditis and dental treatments
This infection is affected by two major factors;
bacteraemias and cardiac lesions where there is
turbulent blood flow. The main type of bacterium involved
with this infection is Viridans streptococci (found in large
numbers in the mouth, especially abundant with poor oral
hygiene) Strep. Mutans and S.sanguis - causing 50% of
cases, and Staphylococcus aureus.

22. Viridans streptococci can be released into the bloodstream
during dental treatment such as tooth extraction and scale
and polishes. However it can also enter the blood stream
during home oral care such as flossing and brushing. In the
majority of cases this causes no harm and no infection of
the heart occurs however there are a variety of factors that
increase the chances of acquiring infective endocarditis;
-The number of the bacteria that are entering the blood
stream.
-Valvular diseases and cardiovascular diseases that are
suffered.
-How well the bacteria adhere to the endocardium.
-If prosthetic heart valves are present.

23. Antibiotic cover is necessary with any tooth extraction, implant surgery,
probing, scaling, intraligamental local anaesthesia and endodontics
beyond the root apex.
. It is vital that the patient who is at risk of infective endocarditis is told
to report back immediately if they suffer any symptoms which can
appear as late as two months after treatment. If multiple treatments are
required for a susceptible patient, then they should be at intervals of
nine to fourteen days, this is necessary so as the bacteria does not
become resistant to the antibiotics.

24. Dental procedures for which prophylaxis is recommended for high
and moderate risk patients:
•Dental extractions .
•Periodontal procedures including probing, scaling and root planing,
surgery and recall maintenance .
•Dental implant placement and reimplantation of avulsed teeth .
•Endodontic instrumentation or surgery only beyond apex .
•Subgingival placement of antibiotic fibers or strips .
•Initial placement of orthodontic bands (but not brackets).
•Intraligamentary local anesthetic injections .
•Prophylactic cleaning of teeth or implants where bleeding is
anticipated.

25. Dental procedures for which prophylaxis is not
recommended:
• Restorative dentistry (operative and prosthetic) with or without the
use of retraction cord (Clinical
• judgment may indicate use of prophylaxis if significant bleeding is
anticipated)
• Local anesthetic injections (other than intraligamentary)
• Intracanal endodontic or restorative treatments
• Placement of rubber dams
• Postoperative suture removal
• Placement of removable prosthodontic/orthodontic appliances
• Taking of oral impressions
• Fluoride treatments
• Taking of oral radiographs
• Orthodontic appliance adjustment
• Shedding of primary teeth

26. Dental care
The patient should keep his teeth and gums clean and healthy.
This will prevent germs from entering the bblood stream through inflamed
tissue and will prevent the need for most dental repairs or dentalsurgery.