Actinomyces viscosus Infections of the Chest in Humans12 HARAGOPAL THADEPALLI and BHAVANI RAO
SUMMARY Actinomyces viscosus infections of the chest are rare in humans. Two such cases were reported previously. We report the clinical features of 3 additional patients. Two had pneumonia, and one had osteomyelitis of the rib. A. viscosus organisms were isolated in pure culture from all 3 patients.
tress or pain. Her dentition was normal for her age, and there was no evidence of periodontal infection. Actinomyces viscosus is an anaerobic or microaerophilic gram-positive, non-acid-fast, faculta- She had soft, discrete, shotty, and nontender lymph nodes in both axillae and the cervical region. On the tive, filamentous, or diphtheroidal organism. It ninth rib, at the costochondral junction, there were can be mistaken for Corynebacterium or Diph2 nontender ulcers with ragged margins, oozing serotheroides. A. viscosus is catalase-positive, where- purulent material and attached to the deeper strucas other species of Actinomyces are catalase-negtures (figure 1A). Physical examination of the lungs ative, which is a distinguishing feature. A. visco- was unremarkable. Her hemoglobin value was 12.2 g sus is part of the normal mouth flora. Previous per 100 ml; hematocrit, 36.9 per cent; white blood reports of A. viscosus infections include: em- cell count, 12,900 cells per mm3; segments, 68 per pyema, infected branchial cyst, pneumonia with cent; basophils, 2 per cent; lymphocytes, 27 per cent; septicemia due to A. viscosus, mandibular ab- monocytes, 2 per cent; and eosinophils, one per cent. Urinalysis was unremarkable. A chest roentgenoscess, endocarditis, and cervicofacial infection gram showed normal lung fields, but there was bony (1-5). W e encountered three patients with destruction of the ninth rib on the right with soft chest infections caused exclusively by A. visco- tissue swelling, without any new bone formation sus. (figure IB). She was treated with 25 mg of clindamycin per kg of body weight per day, given intraCase Reports venously every 6 hours. One week later, this rib was Case No. 1. After an injury due to a fall, 6 months resected and on histopathologic examination, it before admission, a 7-year-old Mexican girl devel- showed extensive granulomatous reaction and fibrooped a slowly enlarging macular lesion on the right sis. A. viscosus was the only bacterium cultured from lower chest for which she was admitted to hospital pus obtained from the chest wall ulcers and the rib. on March 16, 1977. She was afebrile, her pulse was No other aerobic or anaerobic bacteria were found, 120 beats per min, and her respiratory rate was 20 and cultures were negative for fungi and Mycobacbreaths per min. She was active and was in no dis- terium tuberculosis. The patient received clindamycin intravenously for 3 weeks and by mouth for the (Received in original form February 15, 1979 and in following 2 weeks. No relapses or recurrences were revised form April 12,1979) noted during the one-year follow-up. Case No. 2. An 18-year-old man was admitted to 1 From the Department of Medicine, Charles R. hospital on August 4, 1977 for chest pain associated Drew Postgraduate School of Medicine, the Division with cough, hemoptysis, and fever (temperature of of Infectious Diseases, Martin Luther King, Jr. Gen- 40° C) of 3 days' duration. Clinical and roentgenoeral Hospital, and the University of Southern Cali- graphic examination of the chest suggested right upper lobe pneumonia. Laboratory tests showed hemofornia School of Medicine, Los Angeles, Calif. 2 Requests for reprints should be addressed to H. globin of 13.7 g per 100 ml; hematocrit, 40.3 per Thadepalli, M.D., 12021 S. Wilmington Ave., Los An- cent; white blood cell count, 10,500 cells per mm3; polymorphs, 62 per cent; bands, 17 per cent; lymgeles, Calif. 90059. Introduction
AMERICAN REVIEW OF RESPIRATORY DISEASE, VOLUME 120, 1979
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Fig. 1. Note the seropurulent discharge from the ulcers on the chest wall (left) secondary to osteomyelitis of the ninth rib on the right side; (right) caused by Actinomyces viscosus (for details, see Case No. 1). phocytes, 13 per cent; and monocytes, 8 per cent; electrolytes, blood urea nitrogen, glucose, and serum IgA and IgG were within normal limits. Percutaneous transtracheal aspiration on culture yielded only A. viscosus organisms. The patient received 5 g of ticarcillin disodium intravenously every 6 hours for 3 weeks. The cultures were negative for M. tuberculosis and fungi. The chest roentgenogram showed improvement at the end of therapy, cleared 2 weeks after discharge, and remained clear during the 6month follow-up. Case No. 5. A 49-year-old man, was admitted to hospital on July 1, 1977 for loss of appetite, cough with expectoration, night sweats, chest pain on coughing, and fever of 5 days' duration. In 1974, he had had penectomy for carcinoma of the penis and inguinal lymphadenectomy. On physical and roentgenographic examination, he had left lower lobe pneumonia. In addition, he had foul-smelling purulent hydradenitis of both axillae. A gallium-67 scan showed increased uptake in the left lower lobe of the lung. Laboratory results showed hemoglobin of 10.9 g per 100 ml; white blood cell count, 29,100 cells per mm3; polymorphs, 57 per cent; basophils, 29 per cent; lymphocytes, 5 per cent and monocytes, 9 per cent. Transtracheal aspiration yielded a pure culture of A. viscosus. Culture of pus from hydraden-
itis also contained A. viscosus organisms, in addition to Peptostreptococcus intermedius. The patient was treated with intravenous administration of 20g of ticarcillin disodium per day in 4 divided doses, for a period of 3 weeks. He remained asymptomatic for one year. He was readmitted on August 28, 1978 with relapse of the pneumonia of the left lower lobe. Transtracheal aspirate at this time again yielded A. viscosus in pure culture. He was then treated with 20 million units of penicillin per day in 4 divided doses for 3 weeks and was discharged on 2 g of oral penicillin VK per day for 3 more weeks. The patient has been asymptomatic during the nearly 6 months that he has been followed. The minimal inhibitory concentration of 5 isolates of A. viscosus obtained from these 3 patients was determined by the agar-dilution method; details of this technic were the same as those previously reported (6). The susceptibility of the isolates to various antimicrobial agents tested was as noted in table 1.
Discussion Actinomyces is an anaerobic gram-positive bacillus susceptible to penicillin and resistant to amphotericin B. Because it never produces spores,
A.
VISCOSUS
CHEST
INFECTIONS
205
sters, and type 2 was found in humans. Most A. viscosus infections in humans are caused by serotype 2 (1-5). We did not serotype our isoOF VARIOUS ANTIMICROBIAL AGENTS ON lates. A. viscosus, as demonstrated by Engel and ACTINOMYCES VISCOSUS ISOLATED FROM THE THREE CASES REPORTED associates (10) may cause infection either by direct chemotactic effect on polymorphonuclear Antimicrobial cells or by its ability to stimulate host-immune Agent MIC (ng/ml) cells to release mediators of inflammation. Dav1 Penicillin enport and associates (11) reported 6 cases of Ampicillin 2 canine infections caused by this organism, inCyclacillin 2 Carbenicillin 5 cluding two with empyema. In canine empyema, Ticarcillin 5 A. viscosus was found in association with Clos5 Mezlocillin tridium perfringens in one case, but in anPiperacillin 5 other, A. viscosus was isolated in pure culture. Cephalothin 2 4 Cefazolin Lewis and Gorbach (1) reported the first case 4 Cephradine of empyema caused by A. viscosus in associaCefamandole 2 tion with M. tuberculosis. Association of ac4 Cefaclor tinomycotic infections with tuberculosis has been Cefoxitin 2 observed (12). Like Patient 1 in our study, Lew0.5 Tetracycline 0.5 Doxycycline is and Gorbach's patient also had osteomyelitis 0.5 Minocycline of the rib. He responded well to penicillin Lincomycin 0.5 and antituberculosis therapy. Adeniyi-Jones and 0.2 Clindamycin co-workers (2) reported the second patient Chloramphenicol 1.0 Rifampin 1.0 with A. viscosus infection of a branchial cyst. > 50 Ethambutal Gutschik (4) reported a case of human endo> 50 Isoniazid carditis caused by A. viscosus in which it was the only organism isolated from 9 successive blood cultures. This patient also had an apical abscess does not grow on Sabouraud agar, and its cell wall has no chitin, it is not a fungus. There are of the tooth, which was believed to be the 6 recognized species of Actinomyces: A. bovis, source of infection. He responded to parenteral A. israelii, A. meyeri, A. naeslundii, A. odon- penicillin therapy after dental extraction. Radtolyticus, and A. viscosus. Among them, A. is- ford and Ryan (3) reported 2 patients with A. viscosus infection, of which one had multiple raellii an,d A. naeslundii occur most frequently myeloma and a "chest infection." In this pain humans. A. bovis, as currently classified, has tient, one blood culture was positive for A. visnever been associated with human infections cosus. Larsen and co-workers (5) reported cer(7). Between 1974 and 1978, we encountered 30 patients with actinomycotic infections in our vicofacial infection caused by A. viscosus in an hospital. There were 15 cases due to A. israelii, 8-year-old boy. They suggested that a case of suppurative thyroiditis reported by Leers and 9 cases of A. naeslundii infections, and three co-workers (13), believed to be caused by catacaused by A. odontolyticus, in addition to these lase-positive A. naeslundii, may in fact have 3 cases due to A. viscosus. been due to A. viscosus; by current taxonomic Howell (8) first isolated A. viscosus organcriteria, A. naeslundii is a catalase-negative orisms from periodontal lesions in hamsters. A. ganism. viscosus is a member of human and hamster Our report describes 3 additional patients inperiodontal plaque flora. Ellen (9) reported that A. viscosus was absent in the mouth of preden- fected with A. viscosus. The diagnosis in our tate infants, whereas it was found in more than patients was conclusive because A. viscosus was the only organism isolated by percutaneous 50 per cent of children by age 7. Colonization of the mouth with A. viscosus, therefore, seems to transtracheal aspiration in 2 cases and by rib occupy a unique ecologic niche. Patient 1 in our resection in one case. Furthermore, in one pastudy was 7 years old, and the patient reported tient it was the only organism isolated from the by Larsen and associates was 8 years old; they transtracheal aspirate on 2 occasions, one year are the youngest reported thus far with A. vis- apart. These 3 patients represent the first docucosus infection. Two serotypes of A. viscosus mented cases of human chest infections caused have been described. Type 1 was found in ham- exclusively by A. viscosus. TABLE 1
MINIMAL INHIBITORY CONCENTRATION (MIC)
206
THADEPALLI AND RAO
L e r n e r (7) tested 15 strains of A. viscosus against various antimicrobial agents a n d found that they are susceptible to penicillin G, ampicillin, cephaloridine, cephalothin, cephalexin, minocycline, doxycycline, tetracycline, clindamycin, oxacillin, erythromycin, chloramphenicol, vancomycin, fusidic acid, a n d novobiocin, b u t are relatively resistant to lincomycin a n d dicloxacillin. H e r e p o r t e d that metronidazole, k n o w n to b e effective against a n a e r o b i c bacteria, was ineffective against A. viscosus. I n d e e d , Kornm a n a n d Loesche (14) i n c o r p o r a t e d metronidazole i n t o the m e d i u m for d e n t a l cultures to isolate selectively A. viscosus a n d A. naeslundii from the m o u t h . T h e y e x p l a i n e d t h a t t h e antibacterial activity of metronidazole d e p e n d s o n r e d u c t i o n of a highly negative r e d o x p o t e n t i a l , which is absent from A. viscosus, a facultative organism. Penicillin is the d r u g of choice for the t r e a t m e n t of A. viscosus infections. I n o u r study, we used ticarcillin because we were t h e n studying t h e t h e r a p e u t i c efficacy of this a n t i m i c r o b i a l agent in a n a e r o b i c infections. If the p a t i e n t is allergic to penicillin, then clindamycin or doxycycline, to which this organism is highly susceptible in vitro, may be used.
References 1. Lewis R, Gorbach SL. Actinomyces viscosus in man. Lancet 1972; 1:641-2. 2. Adeniyi-Jones C, Minielly JA, Matthews WR. Actinomyces viscosus in a branchial cyst. Am J Clin Pathol 1973; 69:711-3. 3. Radford BL, Ryan, WJ. Isolation of Actinomyces viscosus from two patients with clinical infections. J Clin Pathol 1977; 30:518-20.
4. Gutschik E. Case report: endocarditis caused by Actinomyces viscosus. Scand J Infect Dis 1976; 8:271-74. 5. Larsen J, Bottone EJ, Dikman S, Saphir R. Cervicofacial Actinomyces viscosus infection. J Pediatr 1978; 93:797-801. 6. Roy I, Bach, VT, Thadepalli H. In vitro activity of ticarcillin against anaerobic bacteria compared to that of carbenicillin and penicillin. Antimicrob Agents Chemother 1977; 11:25861. 7. Lerner PI. Susceptibility of pathogenic actinomycetes to antimicrobial compounds. Antimicrob Agents Chemother 1974; 5:302-9. 8. Howell A, Jr. A filamentous microorganism isolated from periodontal plaque in hamsters. Sabouraudia 1963; 3:81-92, 93-105. 9. Ellen RP. Establishment and distribution of Actinomyces viscosus and Actinomyces naeslundii in the human oral cavity. Infect Immun 1976; 14:1119-24. 10. Engel D, Van Epps D, Clagett J. In vivo and in vitro studies on possible pathogenic mechanisms of Actinomyces viscosus. Infect Immun 1976; 14:548-54. 11. Davenport AA, Carter GR, Schirmer RG. Canine actinomycosis due to Actinomyces viscosus: report of six cases. Vet Med Small Anim Clin 1974; 1:1442-7. 12. Thadepalli H, Rambhatla K, Niden AH. Transtracheal aspiration in diagnosis of sputum-smearnegative tuberculosis. JAMA 1977; 238:1037-40. 13. Leers WD, Dussault J, Mullens JE, Volpe R. Suppurative thyroiditis: an unusual case caused by Actinomyces naeslundi. Can Med Assoc J 1969; 101:56-9. 14. Kornman KS, Loesche WJ. New medium for isolation of Actinomyces viscosus and Actinomyces naeslundii from dental plaque. J Clin Microbiol 1978; 7:514-8.
SUMMARY Actinomyces viscosus infections of the chest are rare in humans. Two such cases were reported previously. We report the clinical features of 3 additional patients. Two had pneumonia, and one had osteomyelitis of the rib. A. viscosus organisms were isolated in pure culture from all 3 patients.
tress or pain. Her dentition was normal for her age, and there was no evidence of periodontal infection. Actinomyces viscosus is an anaerobic or microaerophilic gram-positive, non-acid-fast, faculta- She had soft, discrete, shotty, and nontender lymph nodes in both axillae and the cervical region. On the tive, filamentous, or diphtheroidal organism. It ninth rib, at the costochondral junction, there were can be mistaken for Corynebacterium or Diph2 nontender ulcers with ragged margins, oozing serotheroides. A. viscosus is catalase-positive, where- purulent material and attached to the deeper strucas other species of Actinomyces are catalase-negtures (figure 1A). Physical examination of the lungs ative, which is a distinguishing feature. A. visco- was unremarkable. Her hemoglobin value was 12.2 g sus is part of the normal mouth flora. Previous per 100 ml; hematocrit, 36.9 per cent; white blood reports of A. viscosus infections include: em- cell count, 12,900 cells per mm3; segments, 68 per pyema, infected branchial cyst, pneumonia with cent; basophils, 2 per cent; lymphocytes, 27 per cent; septicemia due to A. viscosus, mandibular ab- monocytes, 2 per cent; and eosinophils, one per cent. Urinalysis was unremarkable. A chest roentgenoscess, endocarditis, and cervicofacial infection gram showed normal lung fields, but there was bony (1-5). W e encountered three patients with destruction of the ninth rib on the right with soft chest infections caused exclusively by A. visco- tissue swelling, without any new bone formation sus. (figure IB). She was treated with 25 mg of clindamycin per kg of body weight per day, given intraCase Reports venously every 6 hours. One week later, this rib was Case No. 1. After an injury due to a fall, 6 months resected and on histopathologic examination, it before admission, a 7-year-old Mexican girl devel- showed extensive granulomatous reaction and fibrooped a slowly enlarging macular lesion on the right sis. A. viscosus was the only bacterium cultured from lower chest for which she was admitted to hospital pus obtained from the chest wall ulcers and the rib. on March 16, 1977. She was afebrile, her pulse was No other aerobic or anaerobic bacteria were found, 120 beats per min, and her respiratory rate was 20 and cultures were negative for fungi and Mycobacbreaths per min. She was active and was in no dis- terium tuberculosis. The patient received clindamycin intravenously for 3 weeks and by mouth for the (Received in original form February 15, 1979 and in following 2 weeks. No relapses or recurrences were revised form April 12,1979) noted during the one-year follow-up. Case No. 2. An 18-year-old man was admitted to 1 From the Department of Medicine, Charles R. hospital on August 4, 1977 for chest pain associated Drew Postgraduate School of Medicine, the Division with cough, hemoptysis, and fever (temperature of of Infectious Diseases, Martin Luther King, Jr. Gen- 40° C) of 3 days' duration. Clinical and roentgenoeral Hospital, and the University of Southern Cali- graphic examination of the chest suggested right upper lobe pneumonia. Laboratory tests showed hemofornia School of Medicine, Los Angeles, Calif. 2 Requests for reprints should be addressed to H. globin of 13.7 g per 100 ml; hematocrit, 40.3 per Thadepalli, M.D., 12021 S. Wilmington Ave., Los An- cent; white blood cell count, 10,500 cells per mm3; polymorphs, 62 per cent; bands, 17 per cent; lymgeles, Calif. 90059. Introduction
AMERICAN REVIEW OF RESPIRATORY DISEASE, VOLUME 120, 1979
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Fig. 1. Note the seropurulent discharge from the ulcers on the chest wall (left) secondary to osteomyelitis of the ninth rib on the right side; (right) caused by Actinomyces viscosus (for details, see Case No. 1). phocytes, 13 per cent; and monocytes, 8 per cent; electrolytes, blood urea nitrogen, glucose, and serum IgA and IgG were within normal limits. Percutaneous transtracheal aspiration on culture yielded only A. viscosus organisms. The patient received 5 g of ticarcillin disodium intravenously every 6 hours for 3 weeks. The cultures were negative for M. tuberculosis and fungi. The chest roentgenogram showed improvement at the end of therapy, cleared 2 weeks after discharge, and remained clear during the 6month follow-up. Case No. 5. A 49-year-old man, was admitted to hospital on July 1, 1977 for loss of appetite, cough with expectoration, night sweats, chest pain on coughing, and fever of 5 days' duration. In 1974, he had had penectomy for carcinoma of the penis and inguinal lymphadenectomy. On physical and roentgenographic examination, he had left lower lobe pneumonia. In addition, he had foul-smelling purulent hydradenitis of both axillae. A gallium-67 scan showed increased uptake in the left lower lobe of the lung. Laboratory results showed hemoglobin of 10.9 g per 100 ml; white blood cell count, 29,100 cells per mm3; polymorphs, 57 per cent; basophils, 29 per cent; lymphocytes, 5 per cent and monocytes, 9 per cent. Transtracheal aspiration yielded a pure culture of A. viscosus. Culture of pus from hydraden-
itis also contained A. viscosus organisms, in addition to Peptostreptococcus intermedius. The patient was treated with intravenous administration of 20g of ticarcillin disodium per day in 4 divided doses, for a period of 3 weeks. He remained asymptomatic for one year. He was readmitted on August 28, 1978 with relapse of the pneumonia of the left lower lobe. Transtracheal aspirate at this time again yielded A. viscosus in pure culture. He was then treated with 20 million units of penicillin per day in 4 divided doses for 3 weeks and was discharged on 2 g of oral penicillin VK per day for 3 more weeks. The patient has been asymptomatic during the nearly 6 months that he has been followed. The minimal inhibitory concentration of 5 isolates of A. viscosus obtained from these 3 patients was determined by the agar-dilution method; details of this technic were the same as those previously reported (6). The susceptibility of the isolates to various antimicrobial agents tested was as noted in table 1.
Discussion Actinomyces is an anaerobic gram-positive bacillus susceptible to penicillin and resistant to amphotericin B. Because it never produces spores,
A.
VISCOSUS
CHEST
INFECTIONS
205
sters, and type 2 was found in humans. Most A. viscosus infections in humans are caused by serotype 2 (1-5). We did not serotype our isoOF VARIOUS ANTIMICROBIAL AGENTS ON lates. A. viscosus, as demonstrated by Engel and ACTINOMYCES VISCOSUS ISOLATED FROM THE THREE CASES REPORTED associates (10) may cause infection either by direct chemotactic effect on polymorphonuclear Antimicrobial cells or by its ability to stimulate host-immune Agent MIC (ng/ml) cells to release mediators of inflammation. Dav1 Penicillin enport and associates (11) reported 6 cases of Ampicillin 2 canine infections caused by this organism, inCyclacillin 2 Carbenicillin 5 cluding two with empyema. In canine empyema, Ticarcillin 5 A. viscosus was found in association with Clos5 Mezlocillin tridium perfringens in one case, but in anPiperacillin 5 other, A. viscosus was isolated in pure culture. Cephalothin 2 4 Cefazolin Lewis and Gorbach (1) reported the first case 4 Cephradine of empyema caused by A. viscosus in associaCefamandole 2 tion with M. tuberculosis. Association of ac4 Cefaclor tinomycotic infections with tuberculosis has been Cefoxitin 2 observed (12). Like Patient 1 in our study, Lew0.5 Tetracycline 0.5 Doxycycline is and Gorbach's patient also had osteomyelitis 0.5 Minocycline of the rib. He responded well to penicillin Lincomycin 0.5 and antituberculosis therapy. Adeniyi-Jones and 0.2 Clindamycin co-workers (2) reported the second patient Chloramphenicol 1.0 Rifampin 1.0 with A. viscosus infection of a branchial cyst. > 50 Ethambutal Gutschik (4) reported a case of human endo> 50 Isoniazid carditis caused by A. viscosus in which it was the only organism isolated from 9 successive blood cultures. This patient also had an apical abscess does not grow on Sabouraud agar, and its cell wall has no chitin, it is not a fungus. There are of the tooth, which was believed to be the 6 recognized species of Actinomyces: A. bovis, source of infection. He responded to parenteral A. israelii, A. meyeri, A. naeslundii, A. odon- penicillin therapy after dental extraction. Radtolyticus, and A. viscosus. Among them, A. is- ford and Ryan (3) reported 2 patients with A. viscosus infection, of which one had multiple raellii an,d A. naeslundii occur most frequently myeloma and a "chest infection." In this pain humans. A. bovis, as currently classified, has tient, one blood culture was positive for A. visnever been associated with human infections cosus. Larsen and co-workers (5) reported cer(7). Between 1974 and 1978, we encountered 30 patients with actinomycotic infections in our vicofacial infection caused by A. viscosus in an hospital. There were 15 cases due to A. israelii, 8-year-old boy. They suggested that a case of suppurative thyroiditis reported by Leers and 9 cases of A. naeslundii infections, and three co-workers (13), believed to be caused by catacaused by A. odontolyticus, in addition to these lase-positive A. naeslundii, may in fact have 3 cases due to A. viscosus. been due to A. viscosus; by current taxonomic Howell (8) first isolated A. viscosus organcriteria, A. naeslundii is a catalase-negative orisms from periodontal lesions in hamsters. A. ganism. viscosus is a member of human and hamster Our report describes 3 additional patients inperiodontal plaque flora. Ellen (9) reported that A. viscosus was absent in the mouth of preden- fected with A. viscosus. The diagnosis in our tate infants, whereas it was found in more than patients was conclusive because A. viscosus was the only organism isolated by percutaneous 50 per cent of children by age 7. Colonization of the mouth with A. viscosus, therefore, seems to transtracheal aspiration in 2 cases and by rib occupy a unique ecologic niche. Patient 1 in our resection in one case. Furthermore, in one pastudy was 7 years old, and the patient reported tient it was the only organism isolated from the by Larsen and associates was 8 years old; they transtracheal aspirate on 2 occasions, one year are the youngest reported thus far with A. vis- apart. These 3 patients represent the first docucosus infection. Two serotypes of A. viscosus mented cases of human chest infections caused have been described. Type 1 was found in ham- exclusively by A. viscosus. TABLE 1
MINIMAL INHIBITORY CONCENTRATION (MIC)
206
THADEPALLI AND RAO
L e r n e r (7) tested 15 strains of A. viscosus against various antimicrobial agents a n d found that they are susceptible to penicillin G, ampicillin, cephaloridine, cephalothin, cephalexin, minocycline, doxycycline, tetracycline, clindamycin, oxacillin, erythromycin, chloramphenicol, vancomycin, fusidic acid, a n d novobiocin, b u t are relatively resistant to lincomycin a n d dicloxacillin. H e r e p o r t e d that metronidazole, k n o w n to b e effective against a n a e r o b i c bacteria, was ineffective against A. viscosus. I n d e e d , Kornm a n a n d Loesche (14) i n c o r p o r a t e d metronidazole i n t o the m e d i u m for d e n t a l cultures to isolate selectively A. viscosus a n d A. naeslundii from the m o u t h . T h e y e x p l a i n e d t h a t t h e antibacterial activity of metronidazole d e p e n d s o n r e d u c t i o n of a highly negative r e d o x p o t e n t i a l , which is absent from A. viscosus, a facultative organism. Penicillin is the d r u g of choice for the t r e a t m e n t of A. viscosus infections. I n o u r study, we used ticarcillin because we were t h e n studying t h e t h e r a p e u t i c efficacy of this a n t i m i c r o b i a l agent in a n a e r o b i c infections. If the p a t i e n t is allergic to penicillin, then clindamycin or doxycycline, to which this organism is highly susceptible in vitro, may be used.
References 1. Lewis R, Gorbach SL. Actinomyces viscosus in man. Lancet 1972; 1:641-2. 2. Adeniyi-Jones C, Minielly JA, Matthews WR. Actinomyces viscosus in a branchial cyst. Am J Clin Pathol 1973; 69:711-3. 3. Radford BL, Ryan, WJ. Isolation of Actinomyces viscosus from two patients with clinical infections. J Clin Pathol 1977; 30:518-20.
4. Gutschik E. Case report: endocarditis caused by Actinomyces viscosus. Scand J Infect Dis 1976; 8:271-74. 5. Larsen J, Bottone EJ, Dikman S, Saphir R. Cervicofacial Actinomyces viscosus infection. J Pediatr 1978; 93:797-801. 6. Roy I, Bach, VT, Thadepalli H. In vitro activity of ticarcillin against anaerobic bacteria compared to that of carbenicillin and penicillin. Antimicrob Agents Chemother 1977; 11:25861. 7. Lerner PI. Susceptibility of pathogenic actinomycetes to antimicrobial compounds. Antimicrob Agents Chemother 1974; 5:302-9. 8. Howell A, Jr. A filamentous microorganism isolated from periodontal plaque in hamsters. Sabouraudia 1963; 3:81-92, 93-105. 9. Ellen RP. Establishment and distribution of Actinomyces viscosus and Actinomyces naeslundii in the human oral cavity. Infect Immun 1976; 14:1119-24. 10. Engel D, Van Epps D, Clagett J. In vivo and in vitro studies on possible pathogenic mechanisms of Actinomyces viscosus. Infect Immun 1976; 14:548-54. 11. Davenport AA, Carter GR, Schirmer RG. Canine actinomycosis due to Actinomyces viscosus: report of six cases. Vet Med Small Anim Clin 1974; 1:1442-7. 12. Thadepalli H, Rambhatla K, Niden AH. Transtracheal aspiration in diagnosis of sputum-smearnegative tuberculosis. JAMA 1977; 238:1037-40. 13. Leers WD, Dussault J, Mullens JE, Volpe R. Suppurative thyroiditis: an unusual case caused by Actinomyces naeslundi. Can Med Assoc J 1969; 101:56-9. 14. Kornman KS, Loesche WJ. New medium for isolation of Actinomyces viscosus and Actinomyces naeslundii from dental plaque. J Clin Microbiol 1978; 7:514-8.
