Australian Dental Journal. February, 1978

Volume 23, No. 1 .

Pyogenic dental infections: a ten year review

Robin Woods

ABSTRACT-A review is presented of 140 cases of acute dental pyogenic infections. The types of bacteria asscxiated with these infections and their antibiotic sensitivity patterns are dis- cussed and related to earlier reports. The incidence of antibiotic allergy, the principal contra- indication to the use of certain antibiotics, has been assessed and appropriate alternative antibiotics are considered.

Introduction Antibiotics are prescribed by dentists more fre-

quently than they prescribe any other group of drugsl. Because of this dentists need to know and understand the nature and antibiotic sensitivity patterns of the bacteria responsible for the in- fections they treat. On two other occasions2J bacteria associated

with dental pyogenic infections and their antibiotic sensitivities have been reported. The purpose of this paper is to review the current antibiotic sen- sitivity patterns of bacteria isolated from dental infections and the type of bacteria that are associ- ated with these infections; and further, to evaluate several new chemotherapeutic prepara- tions. The need to evaluate these new preparations has arisen from a number of questions asked during the course of a series of lectures presented throughout Australia on this subject.

The question of choice of an antibiotic has been raised and reviewed previously2.3. A relevant question that has arisen is how often a dentist

Therapeutics Advisory Committee. Report on prescribing drugs by dentists-Sydney, Australian Dental Associa- tion, April, 1975.

Woods, Robin-Antibiotic treatment of pyogenic infec- tions of dental origin. Austral. D. J.. 1 3 2 , 151-153 (Apr.) 1968.

Woods, Robin-An assessment of antibiotics for the treat- ment of pyogenic dental infections. Austral. D. J., 20:1, 10-13 (Feb.) 1975,

107

needs to consider an alternative antibody. Firstly, his choice will be influenced by the nature of the bacteria causing the infection and secondly, some antibiotics may be contraindicated for certain patients, usually because of allergy. To assess the magnitude of this latter problem the relevant in- formation on antibiotic allergy from a survey of patients' medical histories is also presented.

Method Samples of pus were collected on a sterile paper

point or platinum wire, placed in dextrose pep- tone broth' and incubated at 37'C for 24 hours. All the lesions examined were acute periapical infections drained through root canals. The incu- bated broth was examined using a Gram's stain, the broth was then spread on a plate of Diagnostic Sensitivity Test Agar* to which ten per cent de- fibrinated horse blood had been added. A Multo- disk S1* was placed on the inoculated agar which was incubated for 24 hours at 37OC. The zones of inhibition of bacterial growth were observed and the sensitivity pattern of the particular microorganism noted.

Where staphylococci or Gram negative rods were identified in the preliminary broth examina- tion, the culture was also plated on mannitol salt agar* or litmus lactose agar* for further identifica- tion and subculturing.

* Oxoid

108 Australian Dental Journal, February, 1978

TABLE 1

Antibiotics tested

Antibiotic Strength Cases tested

Penicillin Ampicillin Sulphafurazole Erythromycin Lincomycin” Tetracycline Cloxacillin Streptomycin Co-trimoxazolei CephalothinS

1.5 units 2 mcg

100 mcg 10 mcg 10 mcg I0 mcg 5 mcg

10 mcg 25 mcg 30 mcg

140 140 140 140 140 140 89 89 51 5 1

“Courtesy of The Upjohn Co. Pty. Ltd. ?Courtesy of Ro,che, Products Pty. Ltd. $Courtesy of Eli Lilly (Australia) and Company.

TABLE 2 Percentage incidence of pyogenic bacteria 1977,

1974. 1967

1977 1974 1967

Strep. pyogenesr 27.1 28.7 17.9 Strep. mitis - - Strep. salivarius) * 45.0 Strep. viridans - 46.2 38.0 Strep. faecalist 7.9 6.3 25.0 Staphylococci 13.6 10.0 4.8 E. coli 4.3 5.0 10.7 Pseudomonas 0.7 2.5 - Klebsiella 1.4 1.3 2.4 - 1.2 Gaffkya - *Classified Streptococcus Division I. ?Classified Streptococcus Div!sion 11. $Classified Streptococcus Division 111.

Classification in bacteria The classification employed in the eighth edition

of Bergey’s Manual4 was used in which there are some changes from the classification used pre- viously. In this study streptococci were classified as Streptococcus pyogenes, Streptococcus faecalis, Streptococcus mitis, or Streptococcus salivarius. Strep. mitis and Strep. salivarius are grouped, as currently they are both classified in Division 11; previously, they were classified in the Viridans groups. It is convenient to adopt this grouping as they exhibit similar antibiotic profiles. Strepto- cocci are no longer designated in the physiological divisions, pyogenic viridans, lactic, or enterococcus.

Recognition of Staphylococcus aurcus was made on the basis of mannitol fermentations and the Gram negative rods were identified as Eschericliia coli or as being members of the genera Pseudo- monas or Klebsiella7M’. Antibiotics tested

One hundred and forty cases of acute pyogenic infections were examined. The antibiotics tested, their strengths and the number of tests made of each antibiotic are set out in Table 1.

Tests using cloxacillin and streptomycin were discontinued after 89 cases to facilitate the testing of cephalothin, a representative of the cephalo-

4 Deibel R H and Seeley Jnr.-In Bergey’s manual of dedrmkat&e bacterioldgy. Edits:, Buchanan, R. E., and Gibbons, N. E. Baltimore. Williams and Wilkins Co.. 8th ed.. 1974 (D. 490).

5 Bergey’s Manual of diterrninative bacteriology. Edits., Breed R S. Murray E. G. D. and Smith N. R. BaltAore: W;lliams aGd Wilkins ko., 7th ed.,’ 1957.

0 Baird-Parker A. C.-In Bergey’s manual of determina- tive bactiriology 8th ’ed. Op cif . , p. 485.

Cowan, S. T.-Zn, Bergey’s manual of determinative bact- eriology 8th ed. Op. cit.,, p. 295.

9 Doudoroff M. and Palleroni, N. J.-In, Bergey’s manual of detehnat ive bacteriology, 8th ed. Op. cif., p. 217.

!‘Cowan, S. T and Orskov, Ida-In, Bergey’s manual of determinasve bacteriology, 8th ed. O p . d., pp. 321- 324.

Australian Dental Journal, February, 1978 I09

TABLE 3

Incidence arid antibiotic serisitivity patterns of bacteria isolated from 140 cases of pyogcnic dental infections*

Cephalosporin

Eryt hrom ycin

Lincomycin

Ampicillin

Penicillin

Co-trimoxazole

Cloxacillin

Tetracycline

Sulphafurazole

Streptomycin

11/11 (100) 38/38 (100) 36/38 (100) 38/38 (100) 38/38 (100) 8/11 (73 1

25/27 (93)

25/38 (66)

26/38 (69) 3/27 (11)

23/23 (100) 61/63 (97)

61/63 (97)

63/63 (100) 63/63 (100) 16/23

29/40 (73)

20/63 (32) 8/63 (13) 2/40 ( 5 )

(70)

37/40 (93 1

109/112 (97)

102/ 1 12 (91)

105/ 112 (94)

102/112 (91)

27/40 (68)

56/72 (78)

48/112 (43)

35/12 (31) 5/72 (7)

10/11 47/51 (91) (92)

0/28 102/140 (0) (73)

10/11 37/51 (91) (73)

11/28 39/140

The numerator of each fraction is the number of cases sensitive to antibiotic, the denominator is the total number of cases tested, percentage sensitivity is in parenthesis.

sporins and co-trimoxazole, a trimethoprim- sulphamethoxazole combination.

Results Pyogenic bacteria

In dentistry the most frequently isolated bac- teria from pyogenic lesions are streptococci, in fact they appear to account for 80 per cent of the bacteria isolated from these lesions. There were also a substantial number of staphylococci, 13.6 per cent, and Gram negative bacteria, 6.4 per cent, isolated. Table 2 sets out these findings in detail, for convenience the results of the two previous reports2J are also included.

Antibiotic sensitivity patterns The results of the sensitivity tests for the various

groups of bacteria are set out in Table 3. The percentage incidence of sensitivity to the various antibiotics tested has been calculated.

The results presented in Table 3 are grouped

to be consistent with clinical diagnosis, all the streptococci including Sfrep. faecalis, have been placed together, the results from staphylococci and Gram negative bacteria have also been grouped. This has been done as it is often pos- sible to clinically differentiate streptococcal in- fections, the criteria, associated with cellulitis, have been described elsewhere3. Allergies to antibiotics

From the medical histories of 2,839 patients taken prior to treatment, 203 patients (7.2 per cent) had a history of antibiotic allergy. The com- monest allergy was to penicillin, 5.7 per cent, then sulphonamides, 1.6 per cent. Only 0.35 per cent of the patients were allergic to the tetracyclines and 0.21 per cent to erythromycin. Multiple allergies were reported in 18 cases (0.63 per cent) and included allergies to both penicillin and sulphonamides, penicillin and erythromycin, peni- cillin and tetracycline, and tetracycline and erythromycin.

I10 Australian Dental Journal, February, 1978

Discussion organisms to approximately 40 per cent. Although

Pyogenic bacteria in dentistry Considered with the earlier reports2.3 the type

of bacteria responsible for acute dental infections is remarkably constant. There is some minor varia- tion and there is evidence that small epidemics occur from time to time, for instance, in the course of six weeks in August and September, 1976, Strep. faecalis was isolated from dental lesions on five occasions.

Eighty per cent of the bacteria encountered have been streptococci, with very little variation in the three reports. Staphylococcal infections have increased from 4.8 per cent in 19682 to 13.6 per cent in the present study although Gram nega- tive bacteria have been isolated less frequently. Sensitivity to antibiotics

During the ten year period reviewed both peni- cillin and erythromycin have remained effective and reliable for treatment of dental infections. Penicillin remains the first choice for treatment of streptococcal infections and for those for whom penicillin is contraindicated, erythromycin is the alternative. Where it is not possible to differenti- ate clinically the cause of the infection erythromy- cin is the first choice being effective in over 90 per cent of all cases.

Ampicillin appears less effective in this report than in the previous survey3. Amoxycillin, a well absorbed oral preparation which provides high blood levels and a similar antibiotic spectrum to ampicillin has almost replaced oral ampicillin. The reduced effectiveness noted may be a result of the greater use of these preparations and may presage the emergence of some resistant strains. Neither ampicillin nor amoxycillin is sufficiently more effective, compared with penicillin, to justify routine use. The especially good absorption of orally administered amoxycillin with its bacterici- dal properties makes it worth considering for prophylaxis against bacterial endocarditis when indicated.

The penicillinase resistant penicillin cloxacillin may have a place in the treatment of staphylo- coccal infections, although co-trimoxazole appears to be more effective. For dental treatment cloxa- cillin appears to be insufficiently reliable to recom- mend its regular use.

Of the antibiotics reviewed during the last ten years the effectiveness of the tetracyclines has shown the greatest change. Resistant strains of all types of bacteria have emerged during this period. In 1968 over 90 per cent of the bacteria tested were sensitive to the tetracvclinesz, in 1975 this

there is still a place in dentistry for the use of the tetracyclines, for instance, as a mouth wash for the treatment of some oral ulcerations, they can no longer be considered reliable.

Lincomycin, because of its wide spectrum of activity, appears promising, however, the serious gastrointestinal complications that have been as- sociated with its use and the use of clindamycinlo, a similar antibiotic, have placed marked limita- tions on its use in dentistry.

The availability of cephalexin (Keflex, Ceporex), has directed attention to the possible use of cephalosporins and also to the need to define their place in dentistry. Cephalosporins have many properties similar to the penicillins although they are derived from a different source. They are bactericidal, effective against a wide range of bac- teria encountered in dentistry and a preparation suitable for oral administration, cephalexin, is available. Patients who are allergic to penicillin may also be allergic to the cephalosporins although this is not always the case.

Of the antibiotics tested the cephalosporins were the most effective against the total range of bacteria encountered. For the treatment of streptococcal infections cephalosporins offer no great advantage over penicillin and are more costly. As an alterna- tive for patients who are allergic to pencillin they would have to be employed with the utmost caution, used in these circumstances I believe that the patient would have to be treated in a hospital where adequate means are available to treat an acute allergy should it occur.

Cephalosporins are effective against staphylo- cocci and Gram negative bacteria as well as most of the streptococci encountered in dentistry. Although their range of activity is impressive and they appear to be almost free of serious side ef- fects, as satisfactory alternative antibiotics are available the cephalosporins should, I believe, be reserved for cases of special need.

The synergistic combination of trimethoprim and sulphamethoxazole in the ratio of one to five has brought a b u t a renascence of the sulphona- mides. This combination is much more effective than the sulphonamides alone, and is known by the non proprietary name co-trimoxazole, several proprietary preparations are available (Bactrirn, Septrin, and Trib).

Co-trimoxazole is bactericidal in concentrations where its components are usually bacteriostatic. Adverse reactions which occur are similar to those that would occur with a low toxicity sulphonamide. The most common toxic effects of the sulphon-

had been reduced to 75 per cent3 and the present study shows a further decline in sensitive micro- ’” Australian Drug Evaluation Committee-Australian Reg-

istry of Adverse Reactions. Canberra, 1977.

Australian Dental Journal, February, 1978 111

amides are listed by Tolhurst, Buckle and Williamsll as headache, mental depression, general malaise, photosensitization, drug rash, fever, and haematuria or renal pain. An extract from The Australian Registry of Adverse Reactionslo, re- garding co-trimoxazole would support this infor- mation although allergy reactions of various types are the most frequently reported. Patients who are allergic to the sulphonamides will also be allergic to co-trimoxatole.

Although co-trimoxazole is not recommended for the treatment of streptococcal infections being effective in 67 per cent of cases only, it appears to be very effective against staphylococci and Gram negative infections (over 90 per cent) and would be the first choice for treatment of these infections. Effect of allergy on antibiotic choice

The main contraindications to the use of peni- cillin is patient allergy which occurs in 5.7 per cent of cases. Because penicillin is the first choice of antibiotic in many cases the relatively high in- cidence of patient allergy is a real problem to the practising dentist. For this reason alternatives must be considered. Fortunately the incidence of allergy to the main alternative, erythromycin, is not high (0.21 per cent) although the fact that such allergy has been reported makes careful screening of patients a necessity.

Patients who have multiple antibiotic allergies are a special group and deserve great care and consideration. In their treatment plan emphasis and priority should be given to preventive dentistry as the use of any antibiotic could be hazardous.

Conclusions The types of bacteria giving rise to acute dental

infections have been defined in surveys extending

1 1 Tolhurst J C. Buckle G and Williams, S. W.- ChemAthkrapy’ with aniibioiics and allied drugs. Can- berra, National Health and Medical Research Council, 3rd ed., 1972 (p. 13).

over ten years. Streptococci account for 80 per cent of these infections while staphylococci and Gram negative bacteria are responsible for the balance. It is convenient to divide acute dental infections in this way as it lends itself to clinical differentia- tion as well as conveniently dividing antibiotics into two groups for consideration, those effective against streptococci and those effective against the staphylococci and Gram negative bacteria.

For streptococcal infections penicillin remains the first choice and erythromycin the alternative. For staphylococcal and Gram negative infections co-trimoxazole is the first choice with either erythromycin or a cephalosporin as an alternative. Where no differentiation is possible erythromycin remains the first choice.

These recommendations are made as a guide, there are a number of satisfactory antibiotics available and there is nothing that can replace experience and sound clinical judgement in the choice of an appropriate preparation.

Summary The bacterial flora associated with acute dental

pyogenic infections for a ten year period has been reviewed, the choice of antibiotic for the treat- ment of these infections has been discussed in the light of the results of the three surveys presented and the place in the treatment of these infections of co-trimoxazole and the cephalosporins has been defined, A marked increase in strains of bacteria encountered which are resistant to tetra- cyclines has been noted. The nature of the prob- lem of antibiotic allergy, its influence on the choice of, and the need for, alternative antibiotics have been discussed.

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