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Objectives: We undertook to evaluate the microbiology of acute exacerbation of chronic sinusitis (AECS)., Methods: Repeated aspirations of maxillary sinus secretions by endoscopy were performed in 7 patients over a period of 125 to 242 days., Results: Bacteria were recovered for all 22 aspirates, and the number of isolates was between 2 and 4. A total of 54 isolates were isolated: 16 aerobic and facultative bacteria and 38 anaerobic bacteria. The aerobic bacteria were Haemophilus influenzae (7 isolates), Streptococcus pneumoniae (3), Moraxella catarrhalis (3), Staphylococcus aureus (2), and Klebsiella pneumoniae (1). The anaerobic bacteria included pigmented Prevotella and Porphyromonas spp (19), Peptostreptococcus spp (9), Fusobacterium spp (8), and Propionibacterium acnes (2). A change in the types of isolates was noted in all consecutive cultures obtained from the same patients as different organisms emerged and previously isolated bacteria were no longer recovered. An increase in antimicrobial resistance was noted in 6 instances., Conclusions: This study illustrates the microbial dynamics of AECS in which anaerobic and aerobic bacteria prevail, and highlights the importance of obtaining cultures from patients with AECS for guidance in selection of proper antimicrobial therapy.

Aspirates from 48 chronically inflamed maxillary sinuses from patients who had nasal polyposis were processed for aerobic and anaerobic bacteria. Bacterial growth was present in 46 (96%) specimens. Aerobic or facultative bacteria were present in 6 (13%) specimens, anaerobic bacteria alone in 18 (39%), and mixed aerobic and anaerobic bacteria in 22 (48%). There were 110 bacterial isolates (2.4 per specimen). Thirty-nine of the isolates were aerobic or facultative organisms (0.85 per specimen). The predominant aerobic or facultative organisms were: Staphylococcus aureus, microaerophilic streptococci, Haemophilus influenzae and Moraxella catarrhalis. Seventy-one anaerobes were isolated (1.5 per specimen), Peptostreptococcus spp., Prevotella spp., Porphyromonas asaccharolytica and Fusobacterium spp. being predominant. These findings illustrate for the first time the presence of polymicrobial aerobic-anaerobic flora in patients with chronic maxillary sinusitis who had nasal polyposis.

Objective: To assess the role of anaerobic bacteria in acute exacerbation of chronic bronchitis (AECB)., Methods: The level of the Ig-A class to two organisms (Fusobacterium nucleatum and Prevotella intermedia) was determined in the sputum of 25 patients with AECB and 25 control patients. The presence and level of these antibodies were investigated by enzyme-linked immunosorbent assay., Results: The median sputum antibody level for F nucleatum and P intermedia were significantly higher in patients with AECB as compared to control patients (p < 0.05). The IgA levels for F nucleatum was 3.5 times higher in patients with AECB and 3.8 times greater for P intermedia., Conclusions: This study demonstrates for the first time an elevated sputum antibody titers in patients with AECB to F nucleatum and P intermedia.

Aspirates of 108 chronically inflamed maxillary sinuses were processed for aerobic and anaerobic bacteria. There were 295 bacterial isolates: 109 aerobic and facultative, and 186 anaerobic. The predominant aerobic isolates were Staphylococcus aureus (17 isolates), alpha-hemolytic streptococci (14), Pseudomonas aeruginosa (12), Moraxella catarrhalis (10), and Haemophilus spp (8). The predominant anaerobes were Peptostreptococcus spp (61), Prevotella spp (45), Fusobacterium spp (15), and Propionibacterium acnes (14). Analysis of the medical histories revealed a correlation only between the microbial results and previous sinus surgery. Pseudomonas aeruginosa and gram-negative aerobic bacilli (GNAB) were more often isolated in patients who had surgery (9 of 33 patients had P aeruginosa and 17 had GNAB) than in patients who did not have surgery (3 of 75 had P aeruginosa and 7 had GNAB; p < .001). Anaerobes were isolated more often in patients who did not have surgery (69 of 75 patients) than in those who had previous surgery (21 of 33 patients; p < .001). These findings illustrate the unique microbiological features of chronic maxillary sinusitis that persist after sinus surgery.

Objectives: To assess the bacteriology of beta-lactamase (BL) enzyme activity in sputum of 40 patients with acute exacerbation of chronic bronchitis (AECB)., Methods: The microbiology, BL production by the different isolates, and BL contents in the sputum were determined., Results: Eighty-four isolates were recovered (2.1 isolates per specimen), 44 aerobic and facultative (1.1 isolates per specimen), and 40 anaerobic (1.0 isolate per specimen). Aerobic bacteria were recovered in only 9 (22.5%) specimens, anaerobic bacteria in 9 (22.5%), and mixed aerobic and anaerobic bacteria were found in 22 (55%). The predominant aerobic isolates were Streptococcus pneumoniae (15 isolates), Haemophilus influenzae (11), Moraxella catarrhalis and Klebsiella pneumoniae (4 each). The predominant anaerobes were Peptostreptococcus sp. (19), Prevotella sp. (11), and Fusobacterium sp.(6). Mixed flora were present in 25 (62.5%) specimens, and the number of isolates varied from 2 to 5 per specimen. Thirty-nine beta-lactamase-producing bacteria (BLPB) were isolated in 33 (82.5%) of the 40 cases. The predominant aerobic BLPB were H. influenzae, M. catarrhalis, K. pneumoniae, Staphylococcus aureus, and Escherichia coli. The predominant anaerobic BLPB were Prevotella sp. and Fusobacterium sp. Beta-lactamase activity was detected in 26 (79%) of 33 of specimens in which BLPB were isolated, and in none of the seven specimens that did not harbor BLPB., Conclusions: The rapid detection of BL activity in sputum specimens may have implications for the antimicrobial management with AECB.

The aerobic and anaerobic microbiology of intra-abdominal infections associated with diverticulitis was studied in 110 specimens from the peritoneal cavity after intestinal perforation and in 22 specimens from abdominal abscesses. Anaerobic bacteria only were isolated from 17 (15%) of the peritoneal specimens, aerobic bacteria only from 12 (11%) and mixed aerobic and anaerobic flora from 81 (74%). A total of 339 bacterial isolates was detected in peritoneal cultures (3.1 per specimen), comprising 155 aerobes (1.4 per specimen) and 184 anaerobes (1.7 per specimen). Anaerobic bacteria only were isolated in 4 (18%) abscesses, aerobes alone in one (5%) and mixed aerobic and anaerobic flora in 17 (77%). A total of 72 bacterial isolates (3.3 per specimen) was detected in abdominal abscesses - 35 aerobes (1.6 per specimen) and 37 aerobes (1.7 per specimen). The predominant aerobic and facultative bacteria in abdominal infections were Escherichia coli and Streptococcus spp. The most frequently isolated anaerobes were Bacteroides spp. (B. fragilis group), Peptostreptococcus, Clostridium and Fusobacterium spp.

We report the aerobic and anaerobic microbiology of secondarily infected poison ivy dermatitis. The study involved retrospective review of clinical and microbiology laboratory records of patients with secondarily infected poison ivy lesions. Bacterial growth was noted in 33 specimens. Aerobic or facultative anaerobic bacteria only were present in 18 (55%) patients, anaerobic bacteria only in seven (21%), and mixed anaerobic-aerobic bacteria in eight (24%). Forty-five isolates were recovered (1.4 per specimen): 27 aerobic or facultative anaerobic bacteria, and 18 strict anaerobes. The predominant aerobic and facultative anaerobic bacteria were Staphylococcus aureus (13 isolates) and group A beta-haemolytic streptococci (six). The predominant anaerobes were Peptostreptococcus spp. (seven isolates), pigmented Prevotella and Porphyromonas spp. (four) and Fusobacterium spp. (two). Single bacterial isolates were recovered in 18 (55%) patients, eight of which were S. aureus. Nineteen of the organisms isolated from 16 (48%) patients produced the enzyme beta-lactamase. Organisms that resided in the mucous membranes close to the lesions predominated in those infections. Enteric gram-negative rods and Bacteroides fragilis group predominated in leg and buttock lesions. Group A beta-haemolytic streptococci, pigmented Prevotella and Porphyromonas and Fusobacterium spp. were most frequently recovered from lesions of the finger, face and neck. The polymicrobial aetiology of secondarily infected poison ivy lesions, and the association of bacterial flora with the anatomical site of the lesions, are demonstrated.

Objective: To study the aerobic and anaerobic microbiology of wound infections following spinal fusion in children., Methods: Retrospective review of clinical and microbiological records., Results: Aspirates of pus from 18 infection sites showed bacterial growth. Anaerobic bacteria only were recovered in 3 (17%) specimens, aerobic bacteria only in 3 (17%) and mixed aerobic and anaerobic bacteria in 12 (67%). Forty-two isolates were recovered: 18 anaerobes (1.0 isolates per specimen) and 24 aerobes (1.3 per specimen). The predominant anaerobes were Bacteroides sp. (9 isolates, including 8 Bacteroides fragilis group) and 5 Peptostreptococcus sp. The predominant aerobes were Escherichia coli (6) and Proteus sp. (5). An increase in recovery of E. coli and B. fragilis was noted in children with bowel or bladder incontinence., Conclusions: This study highlights the polymicrobial nature and predominance of anaerobic bacteria in wound infections following spinal fusion in children., (Copyright 2000 S. Karger AG, Basel)

The objective of the review was to study the aerobic and anaerobic microbiology of subphrenic abscesses in relation with predisposing conditions. A retrospective review of clinical and laboratory data of 52 patients treated between 1974 and 1988 was conducted. Forty-three (83%) patients developed the abscesses after an operative procedure. These included 11 patients after colonic, 9 patients after gastric or duodenal, 7 patients after abdominal trauma, 7 patients after biliary, and 6 patients after appendix surgery. A total of 194 organisms (3.7 isolates/specimen), 83 aerobic (1.6/specimen), and 111 anaerobes (2.1/specimen) were recovered. Aerobic bacteria only were recovered in 7 (13%) abscesses, anaerobic bacteria only in 11 (21%), and mixed aerobic and anaerobic bacteria in 34 (65%). Polymicrobial infection was present in 47 (90%). The predominant aerobic isolates were Escherichia coli (28 isolates), Enterococcus group D(9), and Staphylococcus aureus (9). The predominant anaerobes were Peptostreptococcus species (33 isolates), Bacteroides fragilis group (25), Clostridium species (13), and Prevotella species (6). The number of isolates/site varied. The number of anaerobic bacteria/site outnumbered or was equal to the number of aerobic or facultatives in all instances, except in abscesses after biliary surgery. Their number/site was especially high in abscesses after appendectomy, and the number of aerobic and anaerobic bacteria was the lowest after gastric or duodenal surgery. S. aureus predominated after gastric, duodenal and posttrauma surgery; B. fragilis predominated after colonic, appendix, and postabdominal trauma surgery; Enterococcus group D predominated after biliary surgery; Fusobacterium and Prevotella species predominated after gastric or duodenal surgery; and Clostridium species predominated after colonic or appendix surgery. These data highlight the polymicrobial aerobic-anaerobic nature of subphrenic abscesses and their correlation with predisposing surgery.

Background: Bacterial infections can occur in lesions of pustular psoriasis (PP). The objective of this study was to establish the aerobic and anaerobic microbiology of secondarily infected PP., Methods: A retrospective 10-year review was carried out of clinical and microbiology laboratory records from patients with secondarily infected PP lesions, whose specimens of infected sites were processed for the presence of aerobic and anaerobic bacteria., Results: Bacterial growth was noted in 23 specimens. Aerobic or facultative anaerobic bacteria only were present in 12 patients (52%), anaerobic bacteria only in four (17%), and mixed anaerobic-aerobic flora was present in seven (30%). Thirty-six isolates were recovered (1.6 per specimen), 23 aerobic or facultative bacteria and 13 strict anaerobes. The predominant aerobic and facultative bacteria were Staphylococcus aureus (15 isolates), Group D Enterococcus (two isolates), and Escherichia coli (two isolates). The predominant anaerobes were Peptostreptococcus spp. (six isolates) and Bacteroides fragilis group, Propionibacterium acnes, and pigmented Prevotella spp. in two each. Single bacterial isolates were recovered in 14 patients (61%), 11 of which were S. aureus. Nineteen of the organisms isolated from 18 patients (78%) produced the enzyme beta-lactamase. S. aureus was isolated from all body sites. Organisms that resided in the mucous membranes close to the lesions predominated in these infections. Enteric Gram-negative rods and Bacteroides fragilis group predominated in lesions on the legs and buttocks. Group A beta-hemolytic streptococci, pigmented Prevotella, and Fusobacterium spp. were most frequently recovered in lesions of the hand., Conclusions: The polymicrobial etiology of secondarily infected PP lesions and the association of bacterial flora with the anatomic site of the lesions were demonstrated.

The aerobic and anaerobic microbiology of surgical-site infections (SSI) following spinal fusion was retrospectively studied. This was done by reviewing the clinical and microbiological records at the Naval Hospital in Bethesda, Md., from 1980 to 1992. Aspirates of pus from 25 infection sites showed bacterial growth. Aerobic bacteria only were recovered from 9 (36%) specimens, anaerobic bacteria only were recovered from 4 (16%), and mixed aerobic and anaerobic bacteria were recovered from 12 (48%). Sixty isolates were recovered: 38 aerobes (1.5 isolates per specimen) and 22 anaerobes (0.9 isolate per specimen). The predominant aerobes were Escherichia coli (n = 8) and Proteus sp. (n = 7). The predominant anaerobes were Bacteroides fragilis group (n = 9) and Peptostreptococcus sp. (n = 6) isolates. An increase in recovery of E. coli and B. fragilis was noted in patients with bowel or bladder incontinence. This study highlights the polymicrobial nature of SSI and the importance of anaerobic bacteria in SSI following spinal fusion.

A retrospective review of the microbiological and clinical data of 17 specimens obtained from axillary hidradenitis suppurativa (HS) over a period of 6 years was undertaken to study the aerobic and anaerobic microbiology of this condition. A total of 42 bacterial isolates (2.5 per specimen) were obtained, 12 aerobic or facultative (0.7 per specimen) and 30 anaerobic or micro-aerophilic (1.8 per specimen). Aerobic and facultative bacteria only were isolated in six (35%) cases, anaerobic bacteria only in seven (41%) and mixed aerobic and anaerobic bacteria in four (24%). The predominant aerobic bacteria were Staphylococcus aureus (six isolates), Streptococcus pyogenes (three) and Pseudomonas aeruginosa (two). The most frequently isolated anaerobes were Peptostreptococcus spp. (10), Prevotella spp. (seven), micro-aerophilic streptococci (four), Fusobacterium spp. (three) and Bacteroides spp. sensu stricto (three). This study highlights the polymicrobial nature and predominance of anaerobic bacteria in axillary HS and the need for antimicrobial thereby to reflect this.

To study the aerobic and anaerobic microbiology of liver and spleen abscesses and correlate the results with predisposing factors, potential causes and routes of infection, clinical and laboratory data of 48 patients with liver abscesses and 29 with spleen abscesses treated between 1970 and 1990 were reviewed retrospectively. In liver abscesses, a total of 116 isolates (2.4 isolates/specimen) was obtained; 43 were aerobic and facultative species (0.9 isolates/specimen) and 73 were anaerobic species or microaerophilic streptococci (1.5 isolates/specimen). Aerobic bacteria only were isolated from 12 (25%) abscesses, anaerobic bacteria only from eight (17%), and mixed aerobic and anaerobic bacteria from 28 (58%); polymicrobial infection was present in 38 (79%). The predominant aerobic and facultative isolates were Escherichia coli (11 isolates), Streptococcus group D (8), Klebsiella pneumoniae (5) and Staphylococcus aureus (4). The predominant anaerobes were Peptostreptococcus spp. (18 isolates), Bacteroides spp. (13), Fusobacterium spp. (10), Clostridium spp. (10) and Prevotella spp. (4). There were 12 isolates of micro-aerophilic streptococci. S. aureus and beta-haemolytic streptococci were associated with trauma; Streptococcus group D, K. pneumoniae and Clostridium spp. with biliary disease; and Bacteroides spp. and Clostridium spp. with colonic disease. In splenic abscesses, a total of 56 isolates (1.9 isolates/specimen) was obtained; 23 were aerobic and facultative species (0.8 isolates/specimen), 31 were anaerobic species or micro-aerophilic streptococci (1.1 isolates/specimen) and two were Candida albicans. Aerobic bacteria only were isolated from nine (31%) abscesses, anaerobic bacteria from eight (28%), mixed aerobic and anaerobic bacteria from 10 (34%) and C. albicans in two (7%); polymicrobial infection was present in 16 (55%). The predominant aerobic and facultative isolates were E. coli (5 isolates), Proteus mirabilis (3), Streptococcus group D (3), K. pneumoniae (3) and S. aureus (4). The predominant anaerobes were Peptostreptococcus spp. (11 isolates), Bacteroides spp. (5), Fusobacterium spp. (3) and Clostridium spp. (3). S. aureus, K. pneumoniae and Streptococcus group D were associated with endocarditis, E. coli with urinary tract and abdominal infection, Bacteroides spp. and Clostridium spp. with abdominal infection and Fusobacterium spp. with respiratory infection.

Clinical and laboratory data from 1973 to 1988 were retrospectively reviewed to study the microbiology of infection following trauma. A total of 368 specimens obtained from 340 trauma patients showed bacterial growth. The traumas included lacerations (163), blunt trauma (76), penetrating trauma (65), bites (20), and open fractures (10). Anaerobic bacteria only were isolated in 119 (32%) specimens, aerobic bacteria only in 58 (16%), and mixed aerobic-anaerobic flora in 191 (52%). A total of 444 anaerobic (1.2 isolates per specimen) and 267 aerobic or facultative (0.7 per specimen) were recovered. The predominant anaerobic bacteria included Bacteroides fragilis group (119 isolates), Peptostreptococcus spp (113), Clostridium spp (78), Prevotella spp (58), and Fusobacterium spp (23). The predominant aerobic bacteria included Escherichia coli (83), Staphylococcus aureus (61), Streptococcus pyogenes (27), Streptococcus group D (16), and Klebsiella pneumoniae (16). The types of infections included abscesses (109), bacteremia (32), bites (13), empyema (10), osteomyelitis (21), peritonitis (52), thrombophlebitis (12), and wounds (116, including posttraumatic wounds, cellulitis, stump wound, decubitus ulcers, myositis, and fasciitis). S. aureus was isolated at all sites. However, organisms of the oropharyngeal flora predominated in infections that originated from that location (ie, head and neck wounds, and abscesses or bites), and those of the gastrointestinal flora predominated in infections that originated from that site (ie, peritonitis, abdominal abscesses, decubitus ulcers). This study showed the polymicrobial nature of many infections that follow trauma.

Background: The role of bacteria in the pathogenesis of chronic venous leg ulcers (CVLU) is unclear. The objective of the study was to establish the aerobic and anaerobic bacteriology of CVLU., Methods: A retrospective review was carried out of the clinical and microbiological laboratory records obtained from patients with CVLU. Microorganisms were grown from 43 specimens obtained from 41 patients., Results: Aerobic or facultative bacteria alone were present in 18 (42%) specimens, anaerobic bacteria only in three (7%), and mixed aerobic-anaerobic flora in 22 (51%). In total, there were 97 isolates, 64 aerobic or facultative and 33 anaerobic, an average of 2.3 isolates per specimen (1.5 aerobes and 0.8 anaerobes). The predominant aerobic organisms were Staphylococcus aureus (26 isolates), group D streptococci (5), and Escherichia coli(5). The predominant anaerobes were Peptostreptococcus spp. (15), Bacteroides fragilis group (6), Propionibacterium acnes (4), and Prevotella spp. (3)., Conclusions: CVLU have a polymicrobial aerobic-anaerobic flora.

The microbiology of needle aspirates from 40 inflamed cervical lymph glands was studied for aerobic and anaerobic bacteria, fungi and mycobacteria. Forty-two bacterial, 11 mycobacterial and six fungal isolates were isolated. Aerobic bacteria only were recovered in 11 (27.5%), anaerobes alone in five (12.5%) and mixed aerobic and anaerobic bacteria in seven (17.5%). Mycobacterium sp. were recovered in 11 (27.5%) and fungi in six (15%). The recovery of anaerobes was associated with dental infection. Eighteen aerobic bacteria were isolated and the predominant ones were Staphylococcus aureus (eight isolates) and group A streptococci (four). Twenty-four anaerobic bacteria were recovered and the predominant ones were: Prevotella sp. (six), Peptostreptococcus sp. (five), Propionibacterium acnes (four) and Fusobacterium sp. (three). These findings demonstrate the role of anaerobic organisms in cervical lymphadenitis and the need to culture aspirated material from the glands for both aerobic and anaerobic microorganisms.

Purpose: To investigate the aerobic and anaerobic microbiology of dacryocystitis., Method: Retrospective review of the 62 clinical and microbiologic records collected between 1980 and 1990., Results: Aerobic or facultative bacteria were recovered in 32 cases (52%), anaerobic bacteria only in 20 cases (32%), mixed aerobic and anaerobic bacteria in seven cases (11%), and fungi in three cases (5%). A total of 94 organisms (1.5 per specimen), which included 56 aerobic or facultative anaerobic organisms, 35 anaerobic organisms, and three fungi, were recovered. The predominant aerobic and facultative bacteria were Staphylococcus aureus (15 isolates), Staphylococcus epidermidis (13 isolates), and Pseudomonas species (seven isolates). The most frequently recovered anaerobes were Peptostreptococcus species (13 isolates), Propionibacterium species (12 isolates), Prevotella species (four isolates), and Fusobacterium species (three isolates). The predominant fungus was Candida albicans (two isolates). Polymicrobial infection was present in 28 cases (45%)., Conclusion: These data highlight the potential importance of anaerobic bacteria in dacryocystitis.

The aerobic and anaerobic microbiology of various types of retroperitoneal abscesses was studied by review of the clinical and laboratory data for 161 patients treated between 1974 and 1990 for such abscesses. These included 109 anterior, 8 posterior, 21 retrofascial, and 23 pelvic retroperitoneal abscesses. A total of 472 organisms (2.9 isolates/specimen)--204 aerobic and facultative (1.3/specimen), and 268 anaerobic (1.7/specimen)--were recovered. Aerobes only were recovered from 34 abscesses (21%), anaerobes only from 34 (21%), and mixed aerobic and anaerobic bacteria from 93 (58%). Polymicrobial infection was present in 132 patients (82%). The predominant aerobic and facultative isolates were Escherichia coli (60 isolates), Klebsiella pneumoniae (20), Streptococcus group D (19), and Staphylococcus aureus (11). The predominant anaerobes were Peptostreptococcus species (95 isolates), Bacteroides fragilis group (66), Prevotella species (22), and Clostridium species (22). The number of anaerobes per site always was greater than the number of aerobic or facultative organisms and was especially high in pelvic abscesses. The number of aerobic and facultative organisms was especially high in pancreatic abscesses. These data highlight the polymicrobial aerobic-anaerobic nature of retroperitoneal abscesses.

The goal of this work was to study the microbiology and clinical characteristics of patients with infections associated with malignancy treated over a period of 17 years. A total of 668 specimens were obtained from 605 patients. The malignancies include 224 hematological malignancies and 381 nonhematogenic malignancies. Anaerobic bacteria only were isolated in 201 (30%) specimens, aerobic bacteria in 226 (34%), mixed aerobic-anaerobic bacteria in 231 (35%) and Candida spp. in 10 (1%). A total of 683 anaerobic (1.0 isolates per specimens) and 592 aerobic or facultative (0.9 per specimen) organisms were recovered. The predominant anaerobic bacteria included Bacteroides fragilis group isolates (181), Peptostreptococcus spp. (166), Prevotella spp. (106), Clostridium spp. (70), and Fusobacterium spp. (43). The predominant aerobic bacteria included Escherichia coli (133), Staphylococcus aureus (100), Klebsiella pneumoniae (48), and Pseudomonas aeroginosa (45). The type of infections included abscesses (221), bacteremia (198), wounds (175), including 61 cellulitis, 24 post-surgical wounds and 23 decubitus ulcers), peritonitis (48), empyema (12), cholecystitis (6) and thrombophlebitis (5). S. aureus and Peptostreptococcus spp. were isolated from all sites. However, organisms of the oropharyngeal flora (Prevotella and Fusobacterium spp.) predominated in local infections and bacteremia that originated from this site (head and neck wounds and abscesses and pulmonary infections), and organisms of the gastrointestinal tract flora predominated in infections that originated from this site (peritonitis, abdominal abscesses and decubitus ulcers). This retrospective study demonstrates polymicrobial features of many infections associated with malignancies.

The microbiology of perirectal abscesses in 144 patients was studied. Aerobic or facultative bacteria only were isolated in 13 (9%) instances, anaerobic bacteria only were isolated in 27 (19%) instances, and mixed aerobic and anaerobic flora were isolated in 104 (72%) instances. A total of 325 anaerobic and 131 aerobic or facultative isolates were recovered (2.2 anaerobic isolates and 0.9 aerobic isolates per specimen). The predominant anaerobes were as follows: Bacteroides fragilis group (85 isolates), Peptostreptococcus spp. (72 isolates), Prevotella spp. (71 isolates), Fusobacterium spp. (21 isolates), Porphyromonas spp. (20 isolates), and Clostridium spp. (15 isolates). The predominant aerobic and facultative bacteria were as follows: Staphylococcus aureus (34 isolates), Streptococcus spp. (28 isolates), and Escherichia coli (19 isolates). These data illustrate the polymicrobial aerobic and anaerobic microbiology of perirectal abscesses.

Our objective was to establish the aerobic and anaerobic microbiology of nonbullous impetigo (NI) in children. We used a retrospective review of clinical microbiology laboratory and patients' records. Specimens were obtained from 40 patients with NI lesions and showed bacterial growth. Aerobic or facultative anaerobic bacteria only were present in 24 patients (60%), strict anaerobic bacteria only in 5 patients (12.5%), and mixed anaerobic-aerobic flora was present in 11 patients (27.5%). Sixty-four isolates were recovered (1.6 per specimen): 43 aerobic or facultative, and 21 anaerobic. The predominant aerobic and facultative bacteria were Staphylococcus aureus (29 isolates), Group A beta hemolytic streptococcus (GABHS) (13 isolates), and Escherichia coli (1 isolate). The predominant anaerobes were Peptostreptococcus spp. (12), pigmented Prevotella spp. (5), Fusobacterium spp. (2), and Bacteroides fragilis (1). Single bacterial isolates were recovered in 17 patients (42.5%), 13 of which were S. aureus. S. aureus alone or mixed with GABHS or Peptostreptococcus spp. were isolated from all body sites. Mixed flora of Peptostreptococcus spp. with Prevotella spp. or Fusobacterium spp. was mostly found in infections of the head and neck, while E. coli mixed with B. fragilis and Peptostreptococcus spp. were isolated from one infection of the buttocks area. Thirty-three organisms isolated from 32 patients (80%) produced the enzyme beta-lactamase. This study demonstrates the polymicrobial aerobic-anaerobic microbiology of NI lesions.

The aerobic and anaerobic microbiology of sinus aspirates obtained during surgery was compared with culture of samples obtained by endoscopy. Six patients with chronic maxillary sinusitis were evaluated. Polymicrobial flora was found in all specimens (two-to-five isolates/sample). A total of 24 isolates (18 anaerobic, five aerobic and one micro-aerophilic) was obtained from sinus aspirates, and 25 isolates (16 anaerobic and nine aerobic) were found in endoscopic specimens. The predominant organisms were Prevotella spp., Fusobacterium nucleatum, Peptostreptococcus spp. and Staphylococcus spp. Concordance in the type and concentration of organisms was found in all cases. Sixteen of the 18 anaerobes isolated from sinus aspirates were also found in the concomitant endoscopic sample. Five aerobic isolates were found in both sinus aspirates and endoscopic samples and their concentration was similar. However, four aerobic gram-positive bacteria (<10(4) cfu/sample) were found only in endoscopy samples. This pilot study demonstrates the usefulness of endoscopic aspiration in the isolation of bacteria from chronically infected maxillary sinuses.

Background: Bacterial infections occur frequently in lesions of atopic dermatitis (AD). The objectives of the study were to establish the aerobic and anaerobic microbiology of secondarily infected AD., Methods: A retrospective review was carried out of clinical and microbiology laboratory records and of data obtained from patients with secondarily infected AD lesions, whose specimens of infected sites were processed for the presence of aerobic and anaerobic bacteria., Results: Bacterial growth was noted in 41 specimens. Aerobic or facultative anaerobic bacteria only were present in 15 patients (36%), anaerobic bacteria only in eight (20%), and mixed anaerobic-aerobic flora was present in 18 (44%). Seventy-two isolates were recovered (1.8 per specimen), 34 aerobic or facultative bacteria, 35 strict anaerobes, and three Candida sp. The predominant aerobic and facultative bacteria were Staphylococcus aureus (12 isolates), Group A beta hemolytic streptococcus in five isolates, and Escherichia coli in four. The predominant anaerobes were Peptostreptococcus spp. (13 isolates), pigmented Prevotella and Porphyromonas spp. in eight, and Fusobacterium spp. in four isolates. Single bacterial isolates were recovered in 14 patients (34%), seven of which were S. aureus. Twenty-one of the organisms isolated from 16 patients (39%) produced the enzyme beta-lactamase. Organisms that resided in the mucous membranes close to the lesions predominated in these infections. Enteric gram-negative rods and Bacteroides fragilis group predominated in lesions on legs and buttocks. Group A beta-hemolytic streptococci, pigmented Prevotella, and Porphyromonas and Fusobacterium spp. were most frequently recovered in lesions of the finger, scalp, face, and neck., Conclusions: The polymicrobial etiology of secondarily infected AD lesions and the association of bacterial flora with the anatomic site of the lesions are demonstrated.

Repeated aspirations of sinus secretions by endoscopy was performed in five patients over a period of 34-50 days and, ultimately, surgical drainage was done in three who presented with acute maxillary sinusitis that did not respond to antimicrobial therapy and became chronic. The aspirates were cultured for aerobic and anaerobic bacteria. Most of the bacteria isolated from the first culture were aerobic or facultative bacteria: Streptococcus pneumoniae (three isolates), Haemophilus influenzae non-type-b (two) and Moraxella catarrhalis (one). Three of these cultures yielded bacteria that were resistant to the antimicrobial agents prescribed for treatment. Failure to respond to therapy was associated with the emergence of resistant aerobic and anaerobic bacteria in subsequent aspirates. These organisms included Fusobacterium nucleatum, pigmented Prevotella and Porphyromonas spp. and Peptostreptococcus spp. Eradication of the infection was achieved in all instances following the administration of antimicrobial agents effective against these bacteria, and in three instances by surgical drainage. This study illustrates the microbial dynamics of maxillary sinusitis that did not respond to antimicrobial therapy.

Aspirate of pus from eight subperiosteal orbital abscesses (SPOAs) and their corresponding infected sinuses were studied for aerobic and anaerobic bacteria. Polymicrobial flora was found in all instances, and the number of isolates varied from two to five. Anaerobes were recovered from all specimens. The predominant isolates were Peptostreptococcus spp, Prevotella spp, Fusobacterium spp, Staphylococcus aureus, and microaerophilic streptococci. Concordance in the microbiological findings between SPOA and the infected sinus was found in all instances. However, certain organisms were only present at one site and not the other. Fourteen beta-lactamase-producing organisms were present in nine specimens. These data confirm the importance of anaerobic bacteria in sinusitis and demonstrate their predominance in the associated SPOA.

Aspirate of pus from 5 periapical abscesses of the upper jaw and their corresponding maxillary sinusitis were studied for aerobic and anaerobic bacteria. Polymicrobial flora were found in all instances, where the number of isolates varied from 2 to 5. Anaerobes were recovered from all specimens. The predominant isolates were Prevotella sp., Porphyromonas sp., Fusobacterium nucleatum, and Peptostreptococcus sp. Concordance in the microbiological findings between periapical abscess and the maxillary sinus flora was found in all instances. However, certain organisms were only present at one site and not the other. Five beta-lactamase-producing organisms were present in the five specimens. These data confirm the importance of anaerobic bacteria in periapical abscesses and demonstrate their predominance in maxillary sinusitis that is associated with them.

Objective: To assess the bacteriology and beta-lactamase enzyme activity in aspirates of 10 acutely and 13 chronically inflamed maxillary sinuses., Results: The predominant organisms isolated in acute sinusitis were Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis, and those found in chronic sinusitis were Prevotella species, Fusobacterium species, and Peptostreptococcus species. Four beta-lactamase-producing organisms (BLPOs) were isolated in four specimens (40%) obtained from acutely inflamed sinuses, and 14 BLPOs were recovered from 10 chronically inflamed sinuses (77%). The predominant BLPOs in acute sinusitis were H influenzae, and M catarrhalis; those in chronic sinusitis were Staphylococcus aureus, Prevotella species, Fusobacterium species, and Bacteroides fragilis., Conclusions: Beta-lactamase activity was detected in 12 (three in acute and nine in chronic sinusitis) of the 14 aspirates that contained BLPOs. The detection of beta-lactamase activity in sinus aspirates provides support for the role of BLPOs in the failure of penicillin therapy in sinusitis.

Repeated aspirations (for a period of 36 to 55 days) of the exudate through an open perforation were performed in seven children with acute otitis media that did not respond to antimicrobial therapy. Penicillin-resistant organisms were present in all but one of the first two aspirates. Failure to respond to antimicrobial therapy was associated with the emergence of resistant anaerobic and aerobic bacteria in the third and fourth cultures. The infection was cured in all instances after administration of antimicrobial agents effective against these bacteria.

Objectives: To study the aerobic and anaerobic microbiology of infected hemorrhoids., Methods: Retrospective review of the clinical microbiology records., Results: Aspirates of pus from infected hemorrhoids in 19 patients showed bacterial growth. Anaerobic bacteria only were recovered in six (32%) specimens, aerobic bacteria only in one (5%), and mixed aerobic and anaerobic bacteria in 12 (63%). Sixty-eight isolates were recovered: 39 anaerobes (2.1 isolates per specimen) and 29 aerobes (1.5 per specimen). The predominant anaerobes were Bacteroides sp. (13 isolates, including 10 Bacteroides fragilis groups) and 13 Peptostreptococcus sp. The predominant aerobes were Escherichia coli (7), Proteus sp. (5), group D streptococci (4), and Pseudomonas sp. (3)., Conclusions: This study highlights the polymicrobial nature and predominance of anaerobic bacteria in infected hemorrhoids.

Objective: To study the aerobic and anaerobic microbiologic characteristics of superficial suppurative thrombophlebitis., Design: Retrospective review of microbiologic and clinical data., Setting: Navy Hospital in Bethesda, Md., Results: Sixty-one isolates, 36 aerobic and 25 anaerobic, were isolated from samples obtained from 42 patients. Aerobic bacteria only were found in 26 (62%) patients; anaerobic only, in 11 (26%); and mixed aerobic and anaerobic bacteria, in five (12%). The predominant aerobic bacteria were Staphylococcus aureus (n = 9), Escherichia coli (n = 7), Pseudomonas aeruginosa (n = 4), and Klebsiella sp (n = 3). The most frequently recovered anaerobic bacteria were Peptostreptococcus sp (n = 8), Propionibacterium acnes (n = 6), Bacteroides fragilis group (n = 5), Prevotella intermedia (n = 3), and Fusobacterium nucleatum (n = 3). Propionibacterium acnes and Peptostreptococcus sp were associated with cannula-related superficial suppurative thrombophlebitis; B fragilis and Enterobacteriaceae, with abdominal surgery or pathology; and S aureus and P aeruginosa and Citrobacter sp, with burns., Conclusion: These data illustrate the importance of anaerobic bacteria in superficial suppurative thrombophlebitis.

Specimens from 32 pustular acne lesions that were inoculated on media supportive for the growth of aerobic and anaerobic bacteria showed bacterial growth. Only aerobic or facultative bacteria were recovered in 15 (47%) specimens, only anaerobic bacteria in 11 (34%) specimens, and mixed aerobic and anaerobic bacteria in 6 (18%) specimens. A total of 57 isolates, 31 anaerobes (1.0 per specimen) and 26 aerobes (0.8 per specimen) were recovered. The predominant isolates were Staphylococcus sp. (19 isolates), Peptostreptococcus sp. (15), and Propionibacterium sp. (10). Twelve (37.5%) of the comedones yielded only one organism. This retrospective study highlighted the polymicrobial nature of over two-thirds of culture positive pustular acne lesions and suggests the potential for pathogenic role of aerobic and anaerobic organisms other than P. acnes and Staphylococcus sp. in acne vulgaris.

The microbiological and clinical characteristics of 83 patients with necrotizing fasciitis (NF) treated over a period of 17 years are presented. Bacterial growth was noted in 81 of 83 (98%) of specimens from patients with NF. Aerobic or facultative bacteria only were recovered in 8 (10%) specimens, anaerobic bacteria only were recovered in 18 (22%) specimens, and mixed-aerobic-anaerobic floras were recovered in 55 (68%) specimens. In total, there were 375 isolates, 105 aerobic or facultative bacteria and 270 anaerobic bacteria, for an average of 4.6 isolates per specimen. The recovery of certain bacteria from different anatomical locations correlated with their distribution in the normal flora adjacent to the infected site. Anaerobic bacteria outnumbered aerobic bacteria at all body sites, but the highest recovery rate of anaerobes was in the buttocks, trunk, neck, external genitalia, and inguinal areas. The predominant aerobes were Staphylococcus aureus (n = 14 isolates), Escherichia coli (n = 12), and group A streptococci (n = 8). The predominant anaerobes were Peptostreptococcus spp. (n = 101), Prevotella and Porphyromonas spp. (n = 40), Bacteroides fragilis group (n = 36), and Clostridium spp. (n = 23). Certain clinical findings correlated with some bacteria: edema with B. fragilis group, Clostridium spp., S. aureus, Prevotella spp. and group A streptococci; gas and crepitation in tissues with members of the family Enterobacteriaceae and Clostridium spp.; and foul odor with Bacteroides spp. Certain predisposing conditions correlated with some organisms: trauma with Clostridium spp.; diabetes with Bacteroides spp., members of the family Enterobacteriaceae, and S. aureus; and immunosuppression and malignancy with Pseudomonas spp. and members of the family Enterobacteriaceae. These data highlight the polymicrobial nature of NF.

Objectives: To investigate the aerobic and anaerobic microbiological characteristics of cellulitis and correlate them with the infection site., Design: Of 342 specimens, 64 obtained using needle aspiration and 278 using swabs were studied over 10 years., Results: Bacterial growth was noted in 15 (23%) of the 64 needle aspirates and 259 (93%) of the 278 swab aspirates. The microbial results of the 15 specimens obtained through needle aspiration are separately presented. Aerobic or facultative bacteria only were present in 138 (53%) of swab samples, anaerobic bacteria only in 69 (27%), and mixed aerobic-anaerobic flora in 52 (20%). In total, there were 582 isolates, 247 aerobic or facultative and 335 anaerobic bacteria, with an average of 2.2 isolates per specimen. The predominance of certain isolates in different anatomical sites correlated with their distribution in the normal flora adjacent to the infected site. The highest recovery rates of anaerobes was from the neck, trunk, groin, external genitalia, and leg areas. Aerobes outnumbered anaerobes in the arm and hand. The predominant aerobes were Staphylococcus aureus, group A streptococci, and Escherichia coli. The predominant anaerobes were Peptostreptococcus sp, Bacteroides fragilis group, Prevotella and Porphyromonas sp, and Clostridium sp. Certain clinical findings correlated with the following organisms: swelling and tenderness with Clostridium sp, Prevotella sp, S aureus, and group A streptococci; regional adenopathy with B fragilis group; bulbous lesions with Enterobacteriaceae; gangrene and necrosis with Peptostreptococcus sp, B fragilis group, Clostridium sp, and Enterobacteriaceae; foul odor with Bacteroides sp; and gas in tissues with Peptostreptococcus sp, B fragilis group and Clostridium sp. Certain predisposing conditions correlated with the following organisms: trauma with Clostridium sp; diabetes with Bacteroides sp, Enterobacteriaceae, and S aureus; and burn with Pseudomonas aeruginosa., Conclusion: These data highlight the polymicrobial nature of cellulitis.

Objective: Assessment of the microbiology and management of patients who suffered from chronic maxillary sinusitis was studied retrospectively., Design: Retrospective analysis of microbiology and antimicrobial therapy of 68 patients who underwent the Caldwell-Luc procedure for chronic sinusitis had not received antimicrobials before surgery and whose cultures showed bacterial growth., Setting: This study was performed at the Naval Hospital in Bethesda, Md., Intervention: Amoxicillin-clavulanic acid was given to 18 patients, amoxicillin or ampicillin to 25, cefaclor to 17, and erythromycin to eight., Results: A total of 183 isolates (123 anaerobic and 60 aerobic) were recovered. Anaerobic organisms only were recovered from 35 (51%), specimens, and aerobic or facultative bacteria only in 12 (18%), and mixed aerobic and anaerobic flora in 21 (31%). Thirty-four aerobic and anaerobic beta-lactamase-producing bacteria were isolated from 28 patients. The 18 patients who received amoxicillin-clavulanic acid had the most rapid and complete response to therapy, none required a change in therapy, and surgical drainage was required in one case. Of 25 patients who received amoxicillin or ampicillin, eight required a change of therapy due to clinical failure (32%), including three who also had surgical drainage. Of 17 that received cefaclor, five had an antibiotic change (29%), one with surgical drainage. Of the eight who were treated with erythromycin, three needed antibiotic change (38%), two with surgical drainage. Resistant organisms were recovered from most of the patients that required therapeutic change., Conclusions: These findings indicate the major role of aerobic and anaerobic beta-lactamase-producing bacteria organisms in the polymicrobial etiology of chronic maxillary sinusitis and illustrate the superiority of therapy effective against these bacteria.

One hundred twenty three microaerophilic streptococci (MS) were isolated from 4,603 specimens submitted for the identification of anaerobic bacteria over the course of 12 years. The MS included 16 Streptococcus constellatus, 43 Streptococcus intermedius and 21 Gemella morbillorum. A total of 81 MS isolates (66%) identified from 75 patients were considered to cause infection. Predisposing or underlying conditions were noted in 48 (64%) patients. The most common conditions were previous surgery (15 instances), trauma (10), diabetes (9), immunodeficiency (6), malignancy, and prosthetic device (5 each). MS were the only bacterial isolates in 23 instances. Mixed infection was encountered in 52 (69%) patients, where the number of isolates varied between two and five (average 2.7). The organisms most commonly isolated with MS were anaerobic cocci, Bacteroides sp. and Enterobacteriaceae; their recovery varied at different sites. Significant infections caused by MS were associated with abscess (29 instances), sinuses (7), obstetrical and gynecological (OBG), chest and wounds (6 each), abdominal (5), and biliary infection (4). Antimicrobial therapy as administered to 71 patients; for 43 patients, in conjunction with surgical drainage or correction. Surgical drainage alone was performed in three patients. Four patients (5%) died. These data illustrate that MS can occasionally be associated with serious infection.

The microbiology and clinical features of empyema were studied retrospectively in 197 patients whose specimens yielded bacterial growth after inoculation for aerobic and anaerobic bacteria. Three hundred forty-three organisms (216 aerobic or facultative and 127 anaerobic organisms) were isolated. Aerobic bacteria were isolated in 127 (64 percent) patients, anaerobic bacteria in 25 (13 percent), and mixed aerobic and anaerobic bacteria in 45 (23 percent). The predominant aerobic or facultative organisms were Streptococcus pneumoniae (70 isolates), Staphylococcus aureus (58), Escherichia coli (17), Klebsiella pneumoniae (16), and Haemophilus influenzae (12). The predominant anaerobes were pigmented Prevotella and Porphyromonas species (24), Bacteroides fragilis group (22), anaerobic cocci (36), and Fusobacterium species (20). beta-Lactamase-producing organisms were recovered in 49 (38 percent) of 128 tested specimens. These included all 42 tested S aureus and 15 B fragilis group, 4 of 9 K pneumoniae, 3 of 9 H influenzae, 3 of 8 pigmented Prevotella and Porphyromonas species, and 2 of 6 E coli. Most patients from whom S pneumoniae and H influenzae were recovered had pneumonia, and most patients with S aureus had pneumonia, aspiration pneumonia, and lung abscesses. The recovery of anaerobic bacteria was mostly associated with the concomitant diagnosis of aspiration pneumonia, and lung, subdiaphragmatic, dental, and oropharyngeal abscesses. These data highlight the importance of anaerobic bacteria in selected cases of empyema.

Eighteen isolates of Bifidobacterium species, 99 of Eubacterium species, and 38 of anaerobic Lactobacillus species were recovered from 3,971 clinical specimens submitted to the anaerobic microbiology laboratory at the National Naval Medical Center over a period of 10 years (June 1978 to June 1988). Clinically significant infection was documented in association with 53 isolates recovered from 52 patients: 8 (44%) of the 18 Bifidobacterium isolates, 30 (30%) of the 99 Eubacterium isolates, and 15 (39%) of the 38 Lactobacillus isolates. The rest of the isolates were considered to be contaminants or to be of uncertain pathogenic significance. The significant infections that were documented mostly involved abdominal abscesses, obstetric and gynecologic sites, and wounds. Predisposing conditions (primarily prior surgery, immunodeficiency, malignancy, presence of a foreign body, or diabetes) were apparent in 7 (87.5%) of the 8 patients infected with Bifidobacterium species, in 23 (85%) of the 27 patients infected with Eubacterium species for whom clinical records were available, and in 8 (67%) of the 12 patients infected with Lactobacillus species for whom clinical records were available. Antimicrobial therapy was administered to 40 (85%) of the 47 patients for whom clinical records were available; such treatment was given in conjunction with surgical drainage or correction for 31 of these 47 patients (66%). No patient died of infection due to anaerobic, nonsporulating, gram-positive rods. These data illustrate that, although Bifidobacterium, Eubacterium, and Lactobacillus species are infrequently associated with infections, they occasionally do cause serious illness.

Purpose: The methods of collecting, transporting, cultivating, and identifying aerobic bacteria in bone and joint infections have improved markedly since the early 1980s. In addition, many of the anaerobes have been reclassified and renamed. The purpose of this study was to provide more current information regarding the incidence of recovery of anaerobic bacteria from clinical specimens of infected bone and joint., Materials and Methods: Specimens from 73 infected bone specimens and 65 infected joints inoculated on media supportive for aerobic and anaerobic bacteria showed bacterial growth., Results: One hundred fifty-seven organisms (2.2 isolates/specimen), consisting of 122 anaerobic bacteria (1.7 isolates/specimen) and 35 facultative or aerobic bacteria (0.5 isolate/specimen), were recovered from the 73 bone specimens. Anaerobic bacteria were recovered with aerobe or facultative bacteria in 24 (33%) instances. The predominant anaerobes were Bacteroides species (49 isolates), anaerobic cocci (45), Fusobacterium species (11), Propionibacterium acnes (7), and Clostridium species (6). Conditions predisposing to bone infections were vascular disease, bites, contiguous infection, peripheral neuropathy, hematogenous spread, and trauma. Pigmented Prevotella and Porphyromonas species were mostly isolated in skull and bite infections (7 of 19), members of the Bacteroides fragilis group in hand and feet infection (12 of 16), and Fusobacterium species in skull, bite, and hematogenous long bone infections. Seventy-four organisms (1.1 isolates/specimen), consisting of 67 anaerobic bacteria (1.0 isolate/specimen) and 7 facultative or aerobic bacteria (0.1 isolate/specimen), were isolated from 65 joint specimens. The predominant anaerobes were P. acnes (24 isolates), anaerobic cocci (17), Bacteroides species (10), and Clostridium species (5). Predisposing conditions to joint infection were trauma, prior surgery, presence of a prosthetic joint, and contiguous infection. P. acnes isolates were associated with prosthetic joints, members of the B. fragilis group with hematogenous spread, and Clostridium species with trauma. The clinical presentation of these cases is discussed., Conclusion: These data highlight the importance of anaerobic bacteria in bone and joint infection.

Specimens from 52 patients with stump wound infection (SWI) were studied for aerobic and anaerobic bacteria. Bacterial growth was present in 44 specimens. Only aerobic or facultative bacteria were recovered in 19 specimens, only aerobic bacteria in 12 and mixed aerobic, facultative and anaerobic bacteria in 13. One hundred and three isolates were recovered (2.3 per specimen)-58 aerobic or facultative (1.3 per specimen) and 45 anaerobic (1.0 per specimen). The predominant isolates were anaerobic cocci (17), Bacteroides species (13 isolates), Staphylococcus aureus (12) and Escherichia coli (11). Polymicrobial infection occurred in 36 instances. S. aureus was more commonly isolated and anaerobic bacteria were less commonly isolated in SWI of the arms, compared with legs. These data highlight the polymicrobial aerobic-anaerobic cause of SWI.

Microbiological and clinical data from 46 patients with external otitis were retrospectively evaluated. Specimens were processed for isolation of aerobic and anaerobic bacteria. A total of 42 aerobic bacteria, 22 anaerobic bacteria, and 3 Candida albicans organisms were recovered. Aerobic bacteria only were isolated from 31 patients (67%), anaerobic bacteria only were isolated from 8 (17%), and mixed aerobic and anaerobic bacteria were isolated from 4 (9%). C. albicans alone was recovered from two patients (4%), and the organism was mixed with aerobic bacteria in one case (2%). The most common isolates were Pseudomonas aeruginosa (19 instances), Peptostreptococcus species (11), Staphylococcus aureus (7), and Bacteroides species (5). One isolate was recovered from 30 patients (65%), 2 isolates were recovered from 11 (24%), and 3 isolates were recovered from 5 (11%). beta-Lactamase activity was detected in 32 isolates recovered from 27 specimens (59%). These data illustrate the polymicrobial nature of external otitis in one-third of the patients and the role of anaerobic bacteria in one-quarter of them. Further prospective studies are warranted for evaluating the role of anaerobic bacteria in this infection and the therapeutic implications of these findings.