ORIGINAL ARTICLE Microbiology of Intracranial Abscesses and Their Associated

Itzhak Brook, MD, MSc

Objective: To evaluate the organisms recovered from in- anaerobes were Fusobacterium species (in 5 correspond- fected sinuses and associated intracranial abscesses (IAs). ing sinuses and abscesses, 1 in a sinus only, and 1 in an IA only), Prevotella species (in 3 corresponding sinuses Design: Retrospective review of findings from aspirate of and abscesses), species (in 2 corre- from 10 infected sinuses and their corresponding IAs. sponding sinuses and abscesses, and 4 in a sinus only), , type b, mi- Setting: Academic medical center. croaerophilic streptococci, and Bacteroides ureolyticus (in 1 corresponding sinus and abscess each). Patients: Ten patients diagnosed as having sinusitis (age pneumoniae was recovered 2 times, only from a sinus. range, 7-58 years). ␣-Hemolytic streptococci and ␤-hemolytic streptococci group F were each isolated once from the sinus. Con- Main Outcome Measure: Aerobic and anaerobic bac- cordance in the microbiological findings between the si- teria findings from infected sinuses and IAs. nus and the IA was found in all instances. However, cer- tain organisms were present at only one or the other site. Results: Polymicrobial flora was found in 9 sinuses and 8 IAs. Anaerobes were isolated from all sinuses and 9 IAs. Conclusion: These data illustrate the concordance in the A total of 26 isolates (2.6 isolates per specimen) were re- recovery of organisms from infected sinuses and their as- covered from the sinuses: 19 anaerobic, 6 aerobic or fac- sociated IA and confirm the importance of anaerobic bac- ultative, and 1 microaerophilic; 17 isolates were found teria in sinusitis and IA. in the IAs (1.7 isolates per site): 13 anaerobic, 2 aerobic or facultative, and 2 microaerophilic. The predominant Arch Otolaryngol Head Neck Surg. 2005;131:1017-1019

NTRACRANIAL ABSCESS (IA) IS A METHODS rare but serious complication of 1,2 paranasal sinusitis. Because of its The 10 patients included in the present report life-threatening nature, IA must be were observed between June 1977 and June 2003. managed as a medical and surgi- Their ages ranged from 7 to 58 years, and 6 were calI emergency. Recognition of the poten- male (Table). Antimicrobial agents were given tial and their origin can assist in to 3 patients prior to drainage: to pa- the proper management of the . tients 2 and 14, erythromycin to patient 9. Most studies have investigated the mi- Cultures of sinuses and IAs were obtained crobiology of IA3-5 and sinusitis6-8 separately during surgery using aseptically performed puncture and aspiration prior to surgical drain- and found it to be monomicrobial most of age. The material was collected either by sy- the time and occasionally polymicrobial due ringe that was immediately sealed and trans- to aerobic and anaerobic . However, ported to the laboratory within 30 minutes or the role of anaerobic bacteria in IA has not by a swab that was dipped into the pus and in- been well studied in most reports because troduced into an anaerobic transport system the methods for recovery of anaerobes were (Port-A-Cul; BBL Microbiology Systems, Cock- inadequate or not consistently used.9-11 eysville, Md) and generally transported to the To my knowledge, the unique micro- laboratory within 2 hours. biology of sinusitis associated with IA and Anaerobic bacteria material was plated onto the correlation between the organisms at 1 of the following: (1) prereduced Brucella blood agar enriched with phytonadione (vita- both sites has not been reported. This re- min K1); (2) anaerobic blood agar containing Author Affiliations: port describes my experience during a 26- colistin and nalidixic acid; or (3) enriched thio- Department of Pediatrics, year period studying the aerobic and an- glycolate broth (containing hemin and vita- Georgetown University School aerobic microbiology of 10 IAs and min K1). It was then incubated inside GasPak of Medicine, Washington, DC. corresponding sinusitis. jars (BBL Microbiology Systems) and exam-

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©2005 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/25/2021 Table. Bacteriology and Clinical Features of Sinusitis and Associated Intracranial Abscesses in 10 Patients

Bacteria Isolated Patient No./ Sex/Age, y Diagnoses Sinus Cavity Intracranial Abscess 1/M/33 Ethmoid and frontal sinusitis, brain Prevotella intermedia (␤Lϩ) Prevotella intermedia (␤Lϩ) abscess Prevotella oralis Fusobacterium nucleatum Streptococcus pneumoniae ␣-hemolytic streptococci 2/F/42 Frontal and maxillary sinusitis, subdural Fusobacterium nucleatum (␤Lϩ) Fusobacterium nucleatum (␤Lϩ) empyema Peptostreptococcus anaerobius Peptostreptococcus micros Peptostreptococcus micros 3/M/31 Frontal sinusitis, Prevotella asaccharolytica Prevotella asaccharolytica Peptostreptococcus species Haemophilus influenzae type b (␤Lϩ) Haemophilus influenzae type b (␤Lϩ) 4/F/48 Pansinusitis, brain abscess Fusobacterium nucleatum Fusobacterium nucleatum Peptostreptococcus intermedius Streptococcus pneumoniae 5/F/40 Sphenoid sinusitis, brain abscess Staphylococcus aureus (␤Lϩ) Staphylococcus aureus (␤Lϩ) Peptostreptococcus species 6/M/58 Ethmoid and frontal sinusitis, subdural Fusobacterium nucleatum (␤Lϩ) Fusobacterium nucleatum (␤Lϩ) empyema 7/M/14 Ethmoid and frontal sinusitis, subdural Prevotella melaninogenica (␤Lϩ) Prevotella melaninogenica (␤Lϩ) empyema Prevotella intermedia Peptostreptococcus magnus Peptostreptococcus magnus Veillonella parvula 8/M/13 Maxillary sinusitis, subdural empyema Microaerophilic streptococci Microaerophilic streptococci Fusobacterium mortiferum Fusobacterium necrophorum Fusobacterium necrophorum 9/M/7 Frontal sinusitis, frontal lobe brain Fusobacterium nucleatum Fusobacterium nucleatum abscess, subdural empyema 10/F/15 Frontal sinusitis, subdural empyema Bacteroides ureolyticus Bacteroides ureolyticus ␤-hemolytic streptococci group F Microaerophilic streptococci

Abbreviation: ␤Lϩ, ␤-lactamase producer.

ined at 48 and 96 hours. Plates that showed growth were main- anaerobic isolates were Fusobacterium species (in 5 cor- tained until the organisms were processed and identified. All responding sinuses and abscesses, 1 in a sinus only, and cultures that showed no growth were kept for at least 7 days 1 in an IA only); Prevotella species (in 3 corresponding to verify that no growth occurred. Anaerobes were identified 8 sinuses and abscesses); Peptostreptococcus species (in 2 by techniques described previously. corresponding sinuses and abscesses and 4 in a sinus For aerobic bacteria, sheep blood (5%), chocolate, and MacConkey agar plates were inoculated at 37°C aerobically only); and Staphylococcus aureus, Haemophilus influen- (MacConkey) and under 5% carbon dioxide (blood and choco- zae type b, microaerophilic streptococci, and Bacteroi- late) and examined at 24 and 48 hours. Aerobic bacteria were des ureolyticus (in 1 corresponding sinus and abscess identified by conventional methods.8 ␤-Lactamase activity was each). Streptococcus pneumoniae was recovered 2 times determined by use of the chromogenic cephalosporin analog from a sinus only. ␣-Hemolytic streptococci and ␤-he- 87/312 method.12 molytic streptococci group F were each isolated once from a sinus. RESULTS Twelve ␤-lactamase–producing organisms were present in 6 sinuses and 6 IAs. These were Fusobacte- Polymicrobial flora was found in 9 sinuses and 8 IAs, and rium nucleatum (4 isolates), Prevotella species (4), S au- the number of isolates ranged from 1 to 4. Anaerobic bac- reus (2), and H influenzae type b (2). teria were isolated from all sinuses and 9 IAs (Table). These anaerobes (including microaerophilic strepto- COMMENT cocci) were the sole bacterial isolates in 5 sinuses (pa- tients 2, 6, 7, 8, and 9) and 7 IAs (patients 1, 2, 4, 6, 7, 8, and 9). Concordance in the microbiological findings be- This study illustrates the importance of anaerobic bac- tween the sinus and the IA was found in all instances. teria in IAs and their predominance in the associated si- However, certain organisms were present only at one site nusitis-affected sinus.2 Our findings confirm the obser- and not at the other sites. vation of Herrmann and Forsen,13 who recovered aerobic A total of 26 isolates (2.6 isolates per specimen) were and anaerobic polymicrobial flora from 2 infected si- recovered from the sinuses: 19 anaerobic, 6 aerobic or nuses and their associated intracranial complication sites. facultative, and 1 microaerophilic; 17 isolates were found Anaerobic bacteria were previously recovered from chroni- in the IAs (1.7 isolates per site): 13 anaerobic, 2 aerobic cally infected sinuses.7,8 Although several aerobic bacte- or facultative, and 2 microaerophilic. The predominant ria such as Streptococcus species, S aureus, and H influ-

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©2005 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/25/2021 enzae were isolated in several instances, the recovery of Submitted for Publication: June 10, 2005; accepted July mainly anaerobic bacteria from all of our patients sug- 13, 2005. gests the chronic nature of their infection. Correspondence: Itzhak Brook, MD, MSc, 4431 Albe- Anaerobic and microaerophilic cocci and gram-negative marle St NW, Washington, DC 20016 (ib6@georgetown and gram-positive anaerobic are the most impor- .edu). tant isolates recovered from brain abscesses. These include Financial Disclosure: None. Bacteroides, Prevotella, Fusobacterium, and species.3-5,13-16 The variations in collection techniques, cul- turing for strict anaerobes, and improper specimen han- REFERENCES dling to prevent contamination may account for differences 1. Skau NK, Nielsen KO, Osgaard O, Molgaard IL, Peitersen E. Intracranial and or- between studies in the final organism identification. bital complications of frontal and ethmoidal sinusitis. Acta Otolaryngol Stockh. Certain organisms such as S pneumoniae and Pepto- 1984;412(suppl):91-94. streptococcus species were only or mainly present at the 2. Brook I, Friedman E, Rodriguez WJ, Controni G. Complications of sinusitis in sinus and not the IA. The lower number of organisms children. Pediatrics. 1980;66:568-572. per specimen recovered from IAs than from sinuses (1.7 3. Yogev R, Bar-Meir M. Management of brain abscesses in children. Pediatr In- fect Dis J. 2004;23:157-159. vs 2.6 isolates per specimen) suggests that not all the bac- 4. Calfee DP, Wispelwey B. Brain abscess. Semin Neurol. 2000;20:353-360. teria present in the sinus cavity are able to reach the in- 5. Brook I. Microbiology and management of brain abscess in children. J Pediatr tracranial space or participate in the IA. Neurol. 2004;2:125-130. Past studies have not found significant correlation be- 6. Wald ER, Milmore GJ, Bowen AD, Ledema-Medina J, Salamon N, Bluestone CD. 9-11 Acute maxillary sinusitis in children. N Engl J Med. 1981;304:749-754. tween sinus cultures and IAs. However, most of the 7. Nord CE. The role of anaerobic bacteria in recurrent episodes of sinusitis and sinus cultures were done using an endoscopic method, . Clin Infect Dis. 1995;20:1512-1524. which can lead to contamination of specimens, and meth- 8. Brook I. Bacteriology of chronic maxillary sinusitis in adults. Ann Otol Rhinol ods adequate for the recovery of anaerobic bacteria were Laryngol. 1989;98:426-428. not used. 9. Gallagher RM, Gross CW, Phillips CD. Suppurative intracranial complications of sinusitis. Laryngoscope. 1998;108:1635-1642. Although surgical drainage is of primary impor- 10. Giannoni CM, Stewart MG, Alford EL. Intracranial complications of sinusitis. tance, administration of antimicrobial therapy is an es- Laryngoscope. 1997;107:863-867. sential part of the treatment of patients with sinusitis and 11. Giannoni C, Sulek M, Friedman EM. Intracranial complications of sinusitis: a pe- IA and other related complications. A growing number diatric series. Am J Rhinol. 1998;12:173-178. 12. O’Callaghan CH, Morris A, Kirby SM, Shingler AH. Novel method for detection of of anaerobic gram-negative bacilli (eg, pigmented Pre- beta-lactamase by using a chromogenic cephalosporin substrate. Antimicrob votella and Fusobacterium species) have acquired resis- Agents Chemother. 1972;1:283-288. tance to through the production of the en- 13. Herrmann BW, Forsen JW Jr. Simultaneous intracranial and orbital complica- zyme ␤-lactamase.17 This has also been observed in the tions of acute rhinosinusitis in children. Int J Pediatr Otorhinolaryngol. 2004; present report, where 6 each of the sinuses and IAs con- 68:619-625. 14. Ayyagari A, Pancholi VK, Kak VK, et al. Bacteriological spectrum of brain ab- tained such organisms. scess with special reference to anaerobic bacteria. Indian J Med Res. 1983; The isolation of polymicrobial aerobic and anaerobic 77:182-186. flora in most of our patients suggests their important role 15. Chun CH, Johnson JD, Hofstetter M, Raff M. Brain abscess: a study of 45 con- in sinusitis and the associated IA. However, further pro- secutive cases. Medicine (Baltimore). 1986;65:415-431. 16. Aebi C, Kaufman F, Schaad UB. Brain abscess in childhood—long-term experience. spective studies are warranted that include larger num- Eur J Pediatr. 1991;150:282-286. bers of patients to evaluate the concurrent of 17. Brook I, Calhoun L, Yocum P. Beta-lactamase–producing isolates of Bacteroi- these organisms in sinusitis and the associated IAs. des species from children. Antimicrob Agents Chemother. 1980;18:164-166.

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