Articulo 8

An investigation of the frequency of bacteraemia

following dental extraction, tooth brushing and chewing

BREMINAND MAHARAJ, YACOOB COOVADIA, AHMED C VAYEJ

Abstract

We conducted a study to determine the frequency of bacteraemias

following dental extraction and common oral procedures,

namely tooth brushing and chewing, and the relationship

between bacteraemia and oral health in black patients.

Positive blood cultures were detected in 29.6% of patients

after dental extraction, in 10.8% of patients after tooth

brushing and in no patients after chewing. No relationship

between the state of oral health, which was assessed using

the plaque and gingival indices, and the incidence of bacteraemia

was found. The duration of bacteraemia was less than

15 minutes. One patient had a positive blood culture prior to

dental extraction; his oral health status was poor. Our study

confirmed that bacteraemia occurs after tooth brushing.

Keywords: bacteraemia following dental procedures

Submitted 30/11/11, accepted 24/2/12

Cardiovasc J Afr 2012; 23: 340–344 www.cvja.co.za

DOI: 10.5830/CVJA-2012-016

Dental treatment has been regarded as a major cause of

infective endocarditis, mainly because of the high frequency of

bacteraemia after various oral procedures and the high recovery

rate of viridans streptococci from the blood of patients with

infective endocarditis.1-3 Awareness of the relationship between

infective endocarditis and dental extraction dates back to 1909,

when Horder noted the association between Streptococcus

viridans in the oral cavity and infective endocarditis in patients

with heart disease.4

Bacteria may invade the bloodstream after a wide variety of

clinical procedures.5 Lewis and Grant postulated that healthy

persons frequently have innocuous, transient bacteraemia

and that the defective heart valve may trap and retain these

organisms, resulting in infective endocarditis.6 Okell and Elliot

noted streptococcal bacteraemia following dental extraction in

61% of their patients.7

Many investigators have assessed the incidence of transient

bacteraemia following various oral procedures. The frequency

of positive blood cultures has ranged from zero to 85% (mean:

40%) for dental extraction, from eight to 79% (mean: 35%) for

dental scaling, from 36 to 88% (mean: 58%) for periodontal

surgery, from seven to 50% (mean: 25%) for tooth brushing or

irrigation, and from zero to 51% (mean: 38%) for chewing.5,8

Bacteraemia has been detected following flossing,9 procedures

used for conservative dentistry,2 intra-oral suture removal,10 and

endodontic treatment.11

Although viridans streptococci are the micro-organisms most

frequently isolated in these studies, considerable differences in

frequency, type and magnitude (colony counts per millimetre

of blood) of post-procedure bacteraemia have been reported.

This is mainly the result of diversities in the type of surgical

procedures (e.g. single vs multiple dental extraction), time of

blood sampling, volume of blood cultured, and the methods used

to isolate and identify the micro-organisms, which hinder the

interpretation and comparison of results. The reports published

before the 1960s may also have underestimated the incidence

of transient bacteraemia, since no refined anaerobic culture

techniques were available.12

Because some of the earlier investigations on antibiotic

prophylaxis had failed to show eradication of bacteria, and the

state of oral health had not been controlled in these studies,13,14

we decided that it would be important to rule out the possible

influence of oral health on post-extraction bacteraemia. Also,

the frequency of bacteraemia following other common oral

procedures, which have been recorded to produce bacteraemia,

had not been evaluated in black patients.

This study was designed to determine:

• the relative frequency of bacteraemia following tooth extraction,

tooth brushing and chewing in black patients

• whether the state of oral health influenced the occurrence of

bacteraemia after these procedures

• the duration of bacteraemia after these procedures.

Methods

Adult black patients attending the Dassenhoek Dental Clinic

in Marianhill near Durban were included in the study, after

informed consent had been obtained. They were healthy, had no

history of cardiovascular disease and had not received antibiotics

in the previous two weeks.

Any patient found to have a dental abscess was excluded.

In addition, in the extraction part of the study, any patient

who needed more than one tooth extracted or required general

anaesthesia was excluded.

The age and gender of each patient was recorded. The

oral health status was evaluated by clinical examination and

calculation of the plaque and gingival index scores, and rated as

excellent, good, average and poor in each patient.15,16 One dental

surgeon performed the oral health status evaluation throughout

the study.

This study was approved by the Ethics Committee of the

Nelson R Mandela School of Medicine, University of Natal.

Department of Therapeutics and Medicines Management,

University of KwaZulu-Natal, Durban, South Africa

BREMINAND MAHARAJ, MB ChB, FCP (SA), MD, PhD, FRCP

(London), maharajb4@ukzn.ac.za

Department of Medical Microbiology, University of KwaZulu-

Natal, Durban, South Africa

YACOOB COOVADIA, MB ChB, FCPath (Micro)

Programme: Oral Health, Department of Health, KwaZulu-

Natal, Durban, South Africa

AHMED C VAYEJ, BDS

AFRICA CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 6, July 2012 341

The frequency of bacteraemia following dental

extraction

In this part of the study, only one tooth was extracted per patient.

The same dental surgeon performed the procedure using dental

forceps; no surgical procedures were used in any patient.

The skin at the site of the venepuncture was prepared using

0.5% chlorhexidine in 70% alcohol. Using standard aseptic

techniques, 8–10 ml of blood was drawn immediately prior to and

at two, five, 15 and 30 minutes after the extraction in each patient.

Three to 5 ml of blood was injected directly into BACTEC

(Becton Dickinson, Maryland, USA) blood culture vials type 6b

(aerobic) and 7d (anaerobic), respectively, after the used needle

was replaced with a new, sterile needle and the rubber septum on

the BACTEC vials was disinfected with alcohol.

The blood culture bottles were transported to the Microbiology

Department, King Edward VIII Hospital, Durban within two

hours of collection and were immediately incubated at 37°C. In

the case of the aerobic bottles, this also included agitation on

BACTEC shakers for the first 24 hours.

The blood culture vials were tested on days one, three, five

and seven, and positive vials were sub-cultured and Gram-stained

smears were prepared. The aerobic vials were sub-cultured onto

chocolate, blood and MacConkey agar plates, which were

incubated for 48 hours in air plus 10% CO2. The anaerobic vials

were sub-cultured onto 10% blood agar plates with and without

amikacin, which were incubated for 48 to 72 hours in anaerobic

gas pak (Becton Dickinson, USA) jars with appropriate controls.

The organisms isolated were further identified using

conventional laboratory methods and the identity of streptococcal

isolates was confirmed using the API Strep 20 (API, France)

system.17

The frequency of bacteraemia following tooth

brushing

In this part of the study, patients were instructed on the proper

technique of tooth brushing by the dental surgeon. Thereafter

they brushed their teeth for about five minutes using a new soft

toothbrush and toothpaste.

The skin preparation and the techniques for blood collection

and blood culture were similar to the first part of the study.

The timing of the blood sampling was immediately prior

to, immediately after, and at five and 15 minutes after tooth

brushing.

The frequency of bacteraemia following chewing

In this part of the study, patients were asked to chew an apple.

The skin preparation and the techniques for blood collection

and blood culture were similar to the first part of the study.

The timing of the blood sampling was immediately prior to

commencement of chewing, when half the apple had been eaten,

when the whole apple had been eaten, and five minutes later.

Statistical analysis

In each part of the study, the patients with plaque and gingival

index scores rated as excellent, good, average and poor were

placed in their respective groups and the number of patients

with positive blood cultures in each group was compared using

the Chi-square test. A p-value < 0.05 was chosen as the level of

significance.

Results

...