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Anaerobic bacteria in oral infections
Anaerobic bacteria in oral infections Charles B. Sabiston, JT., B.S., D.D.S., Ph.D.,* ad W . A . G&l, D.D.S.,** IOWU. City, Iowa, atid Richmond, VIRGINIA
COMMONWFALTH
UNIVERSITY
AND
IJNIVERSITY
Va. OF IOWA
A research project to assess the value of clinical bacteriology in a dental school has been initiated. The project stresses techniques which should result in routine isolation of obligate anaerobes from oral specimens. A series of acute flu&ant abscesses in the mouth has been studied with the use of anaerobic techniques of isolation and culture combined with current methods for characterization and taxonomy of obligate anaerobes. The data indicate that oral abscesses contain a variety of obligate anaerobes. Information presently available indicating the prevalence of staphylococcus and streptococcus might well be reassessed. A number of the organisms isolated were resistant to a wide variety of antibiotics, including penicillin.
I
t is difficult to assess the value of antibiotic therapy in the temporary management of acute abscesses of endodontic and periodontic origin. In most cases of oral abscess surgical drainage is indicated as the principal method of temporary management, with the use of antibiotics relegated to an adjunctive position in the over-all treatment. Since abscesses may respond well to surgical drainage alone, one can rarely determine with any certainty that an antibiotic contributed significantly to the patientis recovery. Since sensitivity testing is rarely done, the selection of antibiotics as adjunctive therapy for oral abscesses is empirical. In an effort to expand our knowledge of the bacteriology of oral infections we have initiated a study of the types of bacteria present in abscesses and their antibiotic-sensitivity patterns. The literature contains surprisingly little information on bacteriology of dental abscesses that have extended beyond the alveolus to cause fluctuant swelling. The standard textbooks on oral surgery refer to bacteria in general but provide few particulars regarding specific bacterial isolants from oral abscesses. Goldberg” described cultures from ninety-three This investigation was supported by Research Grant DE 03662 from the National of Dental Research. “Presently Associate Professor of Periodontics, University of lowa. “*Resident in Oral Surgery, Virginia Commonmealth TJniversit,y.
Institute
187
188
SaGston
a?ld Gold
Oral August,
Rurg$. 1974
patients who had acute dentoalveolar infections which were periapical or periodontal in origin and had spread beyond the alveolus to cause obvious erythematous fluctuant swelling in the buccal, palatal, subgingival, or submandibular areas. I)etails of culture procedures were not provided except to mention the use of blood agar. Specimens were taken, following incision and drainage, with sterile swabs which were placed in transport broth. Staphylococci were isolated from fifty-three of the specimens; twenty-two of these were S. aweus. Fifteen cultures were mixtures of alpha-streptococci and staphylococci. Ten cultures were pure alpha-streptococci, six were Pseudomonas, and two were Proteus. The conclusion is that bacteriologic infection of dentoalveolar origin is now primarily staph,vlococcal. Very different results were obtained by Feldman and Large,l whose sampling technique stressed exclusion of normal oral flora when sampling and whose culture techniques included use of the anaerobic jar. Of seventy-three abscesses sampled in their series, only 3 per cent contained S. aureus. In agreement with numerous other studies, they found streptococci of the viridans group most frequently. We began studying abscesses with anaerobic techniques as a result of several studies, including our work in periodontal disease bacteriology.” Several studies by Crawford and co-workers2, 3, 7 on root canal culturing and postoperative bacteremia indicated the likelihood of anaerobes being a significant part of oral infections. In addition, Moore’s group” at Virginia Polytechnic Institute and State University has clearly shown the prominent position which anaerobes occupy in abscesses throughout the body. The data WC have obtained to date are predictable on the basis of these previous studies with the use of good anaerobic technology. METHODS An abscess has a very low oxidation-reduction potential and, accordingly, anaerobic techniques and cultures are indicated. Our techniques of culture and identification are those developed by the staff of the Anaerobe Laboratory at Virginia Polytechnic Institute and State University. Methods are described in detail in the manual published by the Anaerobe Laboratory.‘z Obtaining adequate specimens without gross contamination by the oral flora and maintaining the specimen in good condition are the pa,ramount problems in bacteriologic investigation of oral lesions. Accordingly, our cases were carefully selected by the Department of Oral Surgery, and were limited to acute fluctuant abscesses of the oral cavity which lent themselves to aspiration of 1 ml. or more of pus with a minimal probability of any significant contamination. The disposable syringe containing the aspirated specimen was placed in a test tube and picked up by one of our staff within 15 minutes. In less than 30 minutes from time of aspiration the specimen was placed under oxygen-free gas. The specimen was grossly examined, a wet preparation was made for phase-contrast. microscopy, a (iram preparation was made, and the following media were inoculated : a brain-heart infusion (prercduced) agar roll tube (supplemented with hcmo. menatlione, and Feast extract) ; a blood agar plate freshly poured from
Volume Number
38 2
Anaerobic
bacteria
in od
infections
189
Table I. Occurrence of organisms in eight alveolar abscesses Fusobaderium nuclentwm Fusobaeterium sp. Fxcultative streptococcus Rxcteroides sp. Peptostreptococcus sp. Laetohacillus sp. (anaerobic) Actinomyees sp. Gram-positive facultative rod S. epidermidis
Occwrence 7/g l/8 c/8 W 2/8
2/8 l/8
l/8 l/8
/
Major
component
5/8 W3 M3 3/8
2/8 V3 W3
prereduced media and reduced in an anaerobe jar; a stock blood agar plate incubated in a CO, jar; and a stock blood agar plate incubated aerobically. All media were incubated at 37O C. Representative colonies were picked in 3 to 5 days and an estimate was made of the relative proportions of the different morphotypes present. The blood media were further incubated for 10 days to detect Bacteroides melaninogenicus. Methods of identification were those of Holdernan and Moore6 and relied on morphology, Gram reaction, a battery of biochemical tests, and gas chromatographic analysis of fatty acids and alcohols produced in culture media, Antibiotic sensitivity testing of obligate anaerobes was by disc diffusion with high-potency discs as described by Wilkins and associates.lO Testing for facultative organisms (Staphylococcus epidermidis) was by standard Kirby-Bauer procedures .I Zone interpretations for cephalothin, penicillin, and tetracycline were according to Wilkins. Zone interpretations for other antibiotics were according to Blair and col1eagues.l RESULTS Table I presents a summary of the organisms identified from eight cases of acute alveolar abscess. The proportion of cases in which the organism was present is listed in the first column. The second column lists the proportion of cases in which the organism was found to constitute at least a third of the isolants present. Fusobacterium nucleafum (F. fusifonne) was present in seven of the eight abscessessampled and was a major constituent of five. Species of Bacteroides were isolated from four of eight cases and were major isolants in three of these. Facultative streptococci were isolated from six of the eight cases but were a major component of only one. Species of Peptostreptococcus, TJactobacillus, Actinomyces, and a gram-positive facultative rod occurred in two or fewer eases.S. epidermidis occurred as a minor component in only one case of our series. Two of the eight cases have been selected for detailed presentation. Both of these patients had infections which had not responded to penicillin therapy. Specimen 6C was taken from a submandibular infection 1 week following a closed reduction of a mandibular fracture. The patient had been receiving penicillin for 3 week before the specimen was taken. Table II presents the isolants from each of four different culture media with an estimation of the proportions which each isolant constituted. The species of lactobacillus were all
190
Sabiston
and
Oral Rurg.
Gold
August,
1974
Table II. Isolants from specimen 6C Medium Roll tube; preredzlced medium; anaerobic: -6C3 Lactobacillws (catenaforme) 6C4 L. bred 6C5 Pusobacterium nucleatwn m00a agar plate; preredzlced mediwm; anaerobic jar: WI0 Bacteroides (ruminicola) 6Cll F. nwleatum 6C12 Facultative streptococcus 6C13 B. melatinogenicus Blood agar plate; CO, jar: 60 Facultative streptococcus 6C8 Facultative streptococcus 6C9 Fncultative streptococcus Blood agar plate; aerobic incubation: 6Cl Facultative streptococrus 6C2 Facultative streptococcus
Per cent of isolants 30
50 20 93 i 1 70 25 5 15
85
anaerobic. The organism designated Bacteroides (ruminicoh) has characteristics resembling this species as well as B. oralis. The number of isolants on the stock blood agar plates (CO, and aerobic incubation) was an estimated several logs lower than anaerobic media, which would indicate that the facultative streptococci were numerically less important than other isolants. The difference in the kinds and proportions of organisms isolated from the different media argues for a variety of media and cultural conditions in studies of this type. As would be expected, Bacteroides required blood and anaerobic conditions. Gram-positive anaerobic rods were favored by the strictly anaerobic roll tube technique. Stock plates without special anaerobic incubation were selective for the facultative organisms present in the specimen. Table III presents the isolants from specimen 7C. In this case a submandibular abscesswas drained and penicillin prescribed 2 days after swelling began. The specimen was taken 6 days after the penicillin therapy was begun when it was noted that the clinical response had not been satisfactory. Once again the numbers of organisms isolated from the stock blood agar plates were several logs lower than the two anaerobic media, indicating lower numbers of the facultat.ire streptococci and S. epidermidis. In this case the numerically significant isolants were F. nucleatum, B. melaninogenicus, B. (ruminicola), and a strain that was lost before identification could be made. Table IV presents antibiotic sensitivity patterns of selected strains from these two cases. The strains designated as B. (ruminicola) were found to be resistant not only to penicillin but to several other antibiotics commonly used in oral infections. CONCLUSIONS The number of casespresented is quite small, and accordingly the information should not be used as a basis for generalizations regardihg the bacterial cause of oral abscessesor the antibiotic of choice in adjunctive therapy. The
Volume Number
Table
Anaerobic
38 2
bacteria
in oral infections
191
III. Isolants from specimen 7C .Mediwm
Per cent of isol4m~s
Roll
tube; preredwed me&hm; anaerobic: 7C4 Fmobadeti nzlcleatzlm 7c5 Bacterooides melaninogeniczls 7C6 Lost Blood agar plate; prmaucca medium; anaerobic 7c7 F. nuoleatwm 7C8 B. melantinogenious 7c9 Lactobacillus sp. 7ClO Bacterdes (rum&cola) Blood agar plate; CO, jar: 7C2 S. epidwmidis 7c3 Facultative streptococcus Blood agar plate; aerobic incubation: 7Cl S. epidermidis
Table
IV. Antibiotic
*Penicillin ery. ; cephalothin,
jar: 15 10 20 55 20 80 100
sensitivity patterns 1Pen.*
Laotobtillus brevis, 6C4 Bacteroicles (rumimwola), S. epidertiti, 7Cl B. m&znhogenicus, 7C8 Lactobacillus 8p., 7c9 B. (rzmtinicola), 7ClO
33 33 33
6ClO
G, pen.; ampicillin, cep. ; tetracycline,
s R R I I R
( Amp.
1 Oxa.
( CU.
1 Ery.
1 Cep.
amp.; oxacillin, tet. ; vancomycin,
1 Van.
/ LC.
S
I nR S I R
1 l’et.
R s R
:::SRS s S
R
i
s i R
s s :
oxa. ; chloramphenicol, van. ; lincomyein, lin.
s s ; chl.;
ii
S s
:
s
erythromycin,
findings do point out the need for extensive study of such infections with the use of good anaerobic technology and extreme care in sampling. Further, when faced with an oral infection which is clinically refractory to penicillin, one should keep in mind the possibility or organisms possessingmultiple antibioticresistance patterns. The Gram stain and sensitivity testing with anaerobic techniques may be extremely helpful. Clindamycin was not used in this series but is now routinely included in our testing. This antibiotic has been demonstrated to be useful in treating infections caused by penicillin-resistant strains of Bacteroides as well as anaerobic infections in general and may be useful in oral infections which prove resistant to penicillin. REFERENCES
1. Blair, J. E., Lennette, E. H., and Truant, J. P., editors: Manual of Clinical Microbiology, Bethesda, 1970, American Society for Microbiology, pp. 299-310. 2. Crawford, J. J., and Shankle, R. J.: Application of Newer Method8 to Study the Importance of Root Canal and Oral Microbiota in Endodontics, ORAL Sum. 14: 1109-1123, 1961. 3. Crawford, J. J., Sconyers, J. R., and Moriarity, J. D.: Use of Prereduced Culture Media to Study Postsurgical Bacteremia, I.A.D.R. Prog. Abst. No. 490, 1971. 4. Feldmann, G., and Large, 0. : The Bacterial,Flora of Submucous Abscesses Originating from Chronic Exacerbating Osteitis, Aeta Odontol. &and. 24: 129-145, 1966. 5. Goldberg, M. H.: The Changing Biologic Nature of Acute Dental Infection, J. Am. Dent. Assoc. 80: 1048-1051, 1970. 6. Holdeman, L. V., and Moore, W. E. C.: Anaerobe Laboratory Manual, Blacksburg, Va., 1972, V. P. I. Anaerobe ‘Laboratory. 7. McMinn, M. T., and Crawford, J. J.: Recovery of Anaerobic Microorganisms from Clinical
192
Sabisto?~ and Gold
Oral August,
Surg. 197-l
Specimens in Prereduced Media Versus Recovery by Routiue Clinical Laboratory Methods, Microbial. 19: 207-213. 1970. 8. M%re, W. E. C., Cato, E. P., and Holdeman L. V.: Anaerobic Bacteria of the Gastrointestinal Flora and Their Occurrence in Cl&al Infections, J. Infect. Dis. 119: 641649, 1969. Bacteria from the Advanceod Peri9. Sabiston, C. B., Jr., and Grigsby, W. R.: Anaerobic odontal Lesion, J. Periodontal. 43: 199-201, 1972. 10. Wilkins, T. D., Holdeman, L. V., Abramson, I. J., and Moore, W. E. C.: Standardized Single-Disc Method for Antibiotic Suscentibi1it.y Testing of Anaerobic Bacteria, Antimicrob. Agents Chemother. 1: 451-459, 1972. ” . ADDI.
Reprint requests to : Dr. C. B. Sabiston, Jr. Department of Periodontology College of Dentistry University of Iowa lawn (‘ity, lowa 52242
COMMONWFALTH
UNIVERSITY
AND
IJNIVERSITY
Va. OF IOWA
A research project to assess the value of clinical bacteriology in a dental school has been initiated. The project stresses techniques which should result in routine isolation of obligate anaerobes from oral specimens. A series of acute flu&ant abscesses in the mouth has been studied with the use of anaerobic techniques of isolation and culture combined with current methods for characterization and taxonomy of obligate anaerobes. The data indicate that oral abscesses contain a variety of obligate anaerobes. Information presently available indicating the prevalence of staphylococcus and streptococcus might well be reassessed. A number of the organisms isolated were resistant to a wide variety of antibiotics, including penicillin.
I
t is difficult to assess the value of antibiotic therapy in the temporary management of acute abscesses of endodontic and periodontic origin. In most cases of oral abscess surgical drainage is indicated as the principal method of temporary management, with the use of antibiotics relegated to an adjunctive position in the over-all treatment. Since abscesses may respond well to surgical drainage alone, one can rarely determine with any certainty that an antibiotic contributed significantly to the patientis recovery. Since sensitivity testing is rarely done, the selection of antibiotics as adjunctive therapy for oral abscesses is empirical. In an effort to expand our knowledge of the bacteriology of oral infections we have initiated a study of the types of bacteria present in abscesses and their antibiotic-sensitivity patterns. The literature contains surprisingly little information on bacteriology of dental abscesses that have extended beyond the alveolus to cause fluctuant swelling. The standard textbooks on oral surgery refer to bacteria in general but provide few particulars regarding specific bacterial isolants from oral abscesses. Goldberg” described cultures from ninety-three This investigation was supported by Research Grant DE 03662 from the National of Dental Research. “Presently Associate Professor of Periodontics, University of lowa. “*Resident in Oral Surgery, Virginia Commonmealth TJniversit,y.
Institute
187
188
SaGston
a?ld Gold
Oral August,
Rurg$. 1974
patients who had acute dentoalveolar infections which were periapical or periodontal in origin and had spread beyond the alveolus to cause obvious erythematous fluctuant swelling in the buccal, palatal, subgingival, or submandibular areas. I)etails of culture procedures were not provided except to mention the use of blood agar. Specimens were taken, following incision and drainage, with sterile swabs which were placed in transport broth. Staphylococci were isolated from fifty-three of the specimens; twenty-two of these were S. aweus. Fifteen cultures were mixtures of alpha-streptococci and staphylococci. Ten cultures were pure alpha-streptococci, six were Pseudomonas, and two were Proteus. The conclusion is that bacteriologic infection of dentoalveolar origin is now primarily staph,vlococcal. Very different results were obtained by Feldman and Large,l whose sampling technique stressed exclusion of normal oral flora when sampling and whose culture techniques included use of the anaerobic jar. Of seventy-three abscesses sampled in their series, only 3 per cent contained S. aureus. In agreement with numerous other studies, they found streptococci of the viridans group most frequently. We began studying abscesses with anaerobic techniques as a result of several studies, including our work in periodontal disease bacteriology.” Several studies by Crawford and co-workers2, 3, 7 on root canal culturing and postoperative bacteremia indicated the likelihood of anaerobes being a significant part of oral infections. In addition, Moore’s group” at Virginia Polytechnic Institute and State University has clearly shown the prominent position which anaerobes occupy in abscesses throughout the body. The data WC have obtained to date are predictable on the basis of these previous studies with the use of good anaerobic technology. METHODS An abscess has a very low oxidation-reduction potential and, accordingly, anaerobic techniques and cultures are indicated. Our techniques of culture and identification are those developed by the staff of the Anaerobe Laboratory at Virginia Polytechnic Institute and State University. Methods are described in detail in the manual published by the Anaerobe Laboratory.‘z Obtaining adequate specimens without gross contamination by the oral flora and maintaining the specimen in good condition are the pa,ramount problems in bacteriologic investigation of oral lesions. Accordingly, our cases were carefully selected by the Department of Oral Surgery, and were limited to acute fluctuant abscesses of the oral cavity which lent themselves to aspiration of 1 ml. or more of pus with a minimal probability of any significant contamination. The disposable syringe containing the aspirated specimen was placed in a test tube and picked up by one of our staff within 15 minutes. In less than 30 minutes from time of aspiration the specimen was placed under oxygen-free gas. The specimen was grossly examined, a wet preparation was made for phase-contrast. microscopy, a (iram preparation was made, and the following media were inoculated : a brain-heart infusion (prercduced) agar roll tube (supplemented with hcmo. menatlione, and Feast extract) ; a blood agar plate freshly poured from
Volume Number
38 2
Anaerobic
bacteria
in od
infections
189
Table I. Occurrence of organisms in eight alveolar abscesses Fusobaderium nuclentwm Fusobaeterium sp. Fxcultative streptococcus Rxcteroides sp. Peptostreptococcus sp. Laetohacillus sp. (anaerobic) Actinomyees sp. Gram-positive facultative rod S. epidermidis
Occwrence 7/g l/8 c/8 W 2/8
2/8 l/8
l/8 l/8
/
Major
component
5/8 W3 M3 3/8
2/8 V3 W3
prereduced media and reduced in an anaerobe jar; a stock blood agar plate incubated in a CO, jar; and a stock blood agar plate incubated aerobically. All media were incubated at 37O C. Representative colonies were picked in 3 to 5 days and an estimate was made of the relative proportions of the different morphotypes present. The blood media were further incubated for 10 days to detect Bacteroides melaninogenicus. Methods of identification were those of Holdernan and Moore6 and relied on morphology, Gram reaction, a battery of biochemical tests, and gas chromatographic analysis of fatty acids and alcohols produced in culture media, Antibiotic sensitivity testing of obligate anaerobes was by disc diffusion with high-potency discs as described by Wilkins and associates.lO Testing for facultative organisms (Staphylococcus epidermidis) was by standard Kirby-Bauer procedures .I Zone interpretations for cephalothin, penicillin, and tetracycline were according to Wilkins. Zone interpretations for other antibiotics were according to Blair and col1eagues.l RESULTS Table I presents a summary of the organisms identified from eight cases of acute alveolar abscess. The proportion of cases in which the organism was present is listed in the first column. The second column lists the proportion of cases in which the organism was found to constitute at least a third of the isolants present. Fusobacterium nucleafum (F. fusifonne) was present in seven of the eight abscessessampled and was a major constituent of five. Species of Bacteroides were isolated from four of eight cases and were major isolants in three of these. Facultative streptococci were isolated from six of the eight cases but were a major component of only one. Species of Peptostreptococcus, TJactobacillus, Actinomyces, and a gram-positive facultative rod occurred in two or fewer eases.S. epidermidis occurred as a minor component in only one case of our series. Two of the eight cases have been selected for detailed presentation. Both of these patients had infections which had not responded to penicillin therapy. Specimen 6C was taken from a submandibular infection 1 week following a closed reduction of a mandibular fracture. The patient had been receiving penicillin for 3 week before the specimen was taken. Table II presents the isolants from each of four different culture media with an estimation of the proportions which each isolant constituted. The species of lactobacillus were all
190
Sabiston
and
Oral Rurg.
Gold
August,
1974
Table II. Isolants from specimen 6C Medium Roll tube; preredzlced medium; anaerobic: -6C3 Lactobacillws (catenaforme) 6C4 L. bred 6C5 Pusobacterium nucleatwn m00a agar plate; preredzlced mediwm; anaerobic jar: WI0 Bacteroides (ruminicola) 6Cll F. nwleatum 6C12 Facultative streptococcus 6C13 B. melatinogenicus Blood agar plate; CO, jar: 60 Facultative streptococcus 6C8 Facultative streptococcus 6C9 Fncultative streptococcus Blood agar plate; aerobic incubation: 6Cl Facultative streptococrus 6C2 Facultative streptococcus
Per cent of isolants 30
50 20 93 i 1 70 25 5 15
85
anaerobic. The organism designated Bacteroides (ruminicoh) has characteristics resembling this species as well as B. oralis. The number of isolants on the stock blood agar plates (CO, and aerobic incubation) was an estimated several logs lower than anaerobic media, which would indicate that the facultative streptococci were numerically less important than other isolants. The difference in the kinds and proportions of organisms isolated from the different media argues for a variety of media and cultural conditions in studies of this type. As would be expected, Bacteroides required blood and anaerobic conditions. Gram-positive anaerobic rods were favored by the strictly anaerobic roll tube technique. Stock plates without special anaerobic incubation were selective for the facultative organisms present in the specimen. Table III presents the isolants from specimen 7C. In this case a submandibular abscesswas drained and penicillin prescribed 2 days after swelling began. The specimen was taken 6 days after the penicillin therapy was begun when it was noted that the clinical response had not been satisfactory. Once again the numbers of organisms isolated from the stock blood agar plates were several logs lower than the two anaerobic media, indicating lower numbers of the facultat.ire streptococci and S. epidermidis. In this case the numerically significant isolants were F. nucleatum, B. melaninogenicus, B. (ruminicola), and a strain that was lost before identification could be made. Table IV presents antibiotic sensitivity patterns of selected strains from these two cases. The strains designated as B. (ruminicola) were found to be resistant not only to penicillin but to several other antibiotics commonly used in oral infections. CONCLUSIONS The number of casespresented is quite small, and accordingly the information should not be used as a basis for generalizations regardihg the bacterial cause of oral abscessesor the antibiotic of choice in adjunctive therapy. The
Volume Number
Table
Anaerobic
38 2
bacteria
in oral infections
191
III. Isolants from specimen 7C .Mediwm
Per cent of isol4m~s
Roll
tube; preredwed me&hm; anaerobic: 7C4 Fmobadeti nzlcleatzlm 7c5 Bacterooides melaninogeniczls 7C6 Lost Blood agar plate; prmaucca medium; anaerobic 7c7 F. nuoleatwm 7C8 B. melantinogenious 7c9 Lactobacillus sp. 7ClO Bacterdes (rum&cola) Blood agar plate; CO, jar: 7C2 S. epidwmidis 7c3 Facultative streptococcus Blood agar plate; aerobic incubation: 7Cl S. epidermidis
Table
IV. Antibiotic
*Penicillin ery. ; cephalothin,
jar: 15 10 20 55 20 80 100
sensitivity patterns 1Pen.*
Laotobtillus brevis, 6C4 Bacteroicles (rumimwola), S. epidertiti, 7Cl B. m&znhogenicus, 7C8 Lactobacillus 8p., 7c9 B. (rzmtinicola), 7ClO
33 33 33
6ClO
G, pen.; ampicillin, cep. ; tetracycline,
s R R I I R
( Amp.
1 Oxa.
( CU.
1 Ery.
1 Cep.
amp.; oxacillin, tet. ; vancomycin,
1 Van.
/ LC.
S
I nR S I R
1 l’et.
R s R
:::SRS s S
R
i
s i R
s s :
oxa. ; chloramphenicol, van. ; lincomyein, lin.
s s ; chl.;
ii
S s
:
s
erythromycin,
findings do point out the need for extensive study of such infections with the use of good anaerobic technology and extreme care in sampling. Further, when faced with an oral infection which is clinically refractory to penicillin, one should keep in mind the possibility or organisms possessingmultiple antibioticresistance patterns. The Gram stain and sensitivity testing with anaerobic techniques may be extremely helpful. Clindamycin was not used in this series but is now routinely included in our testing. This antibiotic has been demonstrated to be useful in treating infections caused by penicillin-resistant strains of Bacteroides as well as anaerobic infections in general and may be useful in oral infections which prove resistant to penicillin. REFERENCES
1. Blair, J. E., Lennette, E. H., and Truant, J. P., editors: Manual of Clinical Microbiology, Bethesda, 1970, American Society for Microbiology, pp. 299-310. 2. Crawford, J. J., and Shankle, R. J.: Application of Newer Method8 to Study the Importance of Root Canal and Oral Microbiota in Endodontics, ORAL Sum. 14: 1109-1123, 1961. 3. Crawford, J. J., Sconyers, J. R., and Moriarity, J. D.: Use of Prereduced Culture Media to Study Postsurgical Bacteremia, I.A.D.R. Prog. Abst. No. 490, 1971. 4. Feldmann, G., and Large, 0. : The Bacterial,Flora of Submucous Abscesses Originating from Chronic Exacerbating Osteitis, Aeta Odontol. &and. 24: 129-145, 1966. 5. Goldberg, M. H.: The Changing Biologic Nature of Acute Dental Infection, J. Am. Dent. Assoc. 80: 1048-1051, 1970. 6. Holdeman, L. V., and Moore, W. E. C.: Anaerobe Laboratory Manual, Blacksburg, Va., 1972, V. P. I. Anaerobe ‘Laboratory. 7. McMinn, M. T., and Crawford, J. J.: Recovery of Anaerobic Microorganisms from Clinical
192
Sabisto?~ and Gold
Oral August,
Surg. 197-l
Specimens in Prereduced Media Versus Recovery by Routiue Clinical Laboratory Methods, Microbial. 19: 207-213. 1970. 8. M%re, W. E. C., Cato, E. P., and Holdeman L. V.: Anaerobic Bacteria of the Gastrointestinal Flora and Their Occurrence in Cl&al Infections, J. Infect. Dis. 119: 641649, 1969. Bacteria from the Advanceod Peri9. Sabiston, C. B., Jr., and Grigsby, W. R.: Anaerobic odontal Lesion, J. Periodontal. 43: 199-201, 1972. 10. Wilkins, T. D., Holdeman, L. V., Abramson, I. J., and Moore, W. E. C.: Standardized Single-Disc Method for Antibiotic Suscentibi1it.y Testing of Anaerobic Bacteria, Antimicrob. Agents Chemother. 1: 451-459, 1972. ” . ADDI.
Reprint requests to : Dr. C. B. Sabiston, Jr. Department of Periodontology College of Dentistry University of Iowa lawn (‘ity, lowa 52242