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This review describes the microbiology, diagnosis and management of bacteremia caused by …
Biology Articles » Microbiology » Clinical review: Bacteremia caused by anaerobic bacteria in children » Microbiology
Anaerobic bacteremia has rarely been described in pediatric patients [13,14]. Sanders and Stevenson  in a review of the literature in 1968 summarized 11 cases of Bacteroides bacteremias in children. In one study, anaerobic organisms were recovered from 6 of 34 children who required general anesthesia and nasotracheal intubation for dental repair . Another study documented bacteremia in 28 children who were undergoing dental manipulations . Among the 28 isolates recovered, 21 were anaerobes (Propionibacterium sp., nine; Veillonella alcalescens, five; Prevotella melaninogenica, three; Peptostreptococcus sp., two; and Eubacterium sp. and Fusobacterium sp., one each).
Brook et al.  reviewed their experience in recovery of anaerobes in the blood over a 12-month period. A total of 13 blood cultures were positive and contained 14 anaerobic agents: five were Bacteroides fragilis, three others were Bacteroides sp., two were Fusobacterium sp., three were Propi-onibacterium sp., and one was Peptostreptococcus sp. In one instance two organisms were isolated from a blood culture: Peptostreptococcus sp. and Fusobacterium sp.
Dunkle et al.  recovered 14 anaerobes from blood cultures over a 1-year study. The dominant anaerobes rec overed were Clostridium sp. (four), Fusobacterium nucleatus (three species), Gram-positive cocci (three species), and B. fragilis (two species). Although 27 isolates of Propionibacterium acnes were recovered, only three were associated with clinical infection.
Thirmuoothi et al.  reviewed their experience over a period of 18 months, and reported 35 anaerobic isolates from 34 blood cultures. The predominant isolates were four each of Gram-positive cocci and Bacteroides sp. and two isolates each of Fusobacterium sp., Bifidobacterium sp., and Clostridium sp. Although Propionibacterium sp. were recovered in 18 instances, there was no apparent relationship between their recovery from the blood and the 18 patients' clinical illness.
Brook and colleagues  summarized their experience in the diagnosis of anaerobic bacteremia noted in 28 children. Twenty-nine anaerobic isolates were recovered from 28 patients ranging in age from 1 week to 15 years. Of these isolates, 14 were Bacteroides sp. (11 of which belonged to the B. fragilis group); four were Clostridium sp.; four were anaerobic Gram-positive cocci; four were P. acnes; and three were Fusobacterium sp. Although the predominant isolate from blood cultures (56–65%) is P. acnes [2,3], a normal inhabitant of the skin, many of these isolates may reflect contamination of the blood cultures by the skin flora. Propionibacterium acnes can cause bacteremia, however, especially in association with shunt infections . All of the patients with P. acnes bacteremia included in the study by Brook et al.  had clinical infection, and all but one responded to antimicrobial therapy. Furthermore, two patients had meningitis caused by this organism after installation of cardiovascular shunts.
An important aspect of anaerobic bacteremia is that anaerobes frequently are present in cases of polymicrobial bacteremia , reflecting the fact that localized anaerobic infections are usually polymicrobial. Polymicrobial bacteremia involving anaerobic bacteria were reported by several authors. Frommell and Todd  reported 56 children with bacteremia with multiple bacterial isolates. Five anaerobes were isolated: two Bacteroides sp., two Peptostreptococci and one Clostridium perfringens. Rosenfeld and Jameson  reported a 15-year-old child with polymicrobial bacteremia involving seven isolates (including four Bacteroides sp. and an anaerobic cocci) associated with pharyngotonsilli-tis. Seidenfeld et al.  reported an adolescent with a fatal bacteremia caused by Fusobacterium necrophorum and Pep-tostreptococcus sp. associated with peritonsillar abscess. Givner et al.  recovered Bacteroides capillosus with Corynebacterium hemolyticum from the blood of a child with primary Epstein–Barr virus infection who developed sinusitis.
Caya and Truant summarized 65 cases of non-infant pediatric clostridial bacteremia . The predominant isolates were Clostridium septicum (25 isolates), Clostridium perfringens (21 isolates) and Clostridium tertium (six isolates). Of the 63 children analyzed, 29 (46%) survived their episode of clostridial bacteremia. Three clinical indices were shown to have a statistically significant negative impact on survival: hypotension, hemolysis and lack of antibiotic therapy. Of the 36 patients with known underlying neoplastic disease, 27 had acute leukemia, five had sarcoma, three had a malignant lymphoproliferative disorder and one had glioblastoma multiforme. Of the 23 patients with no underlying neoplasia, three of them had cyclic neutropenia, two were in sickle cell disease crisis, two had neutropenia associated with aplastic anemia, and one was mildly immunocompromised as a result of renal transplantation.
Brook reported the microbiology of 101 specimens obtained from 95 children with malignancy . A total of 17 patients had bacteremia. Four had Escherichia coli, in one instance mixed with B. fragilis. Bacteroides fragilis group isolates were recovered in three instances (two in patients with leukemia who had a perirectal abscess), Staphylococcus aureus in three patients, Clostridium spp. in two (one C. perfringens and one C. septicum) and two Proteus spp.
Brook summarized clinical and microbiological data of 296 adults with anaerobic bacteremia . Anaerobes were isolated with aerobic or facultative bacteremia in 23 instances. The B. fragilis group accounted for 148 (70%) of 212 isolates of anaerobic Gram-negative bacilli. Bacteroides fragilis accounted for 78% and B. thetaiotaomicron for 14%. Among other species, there were 20 (6%) Fusobacterium organisms, 63 (18%) Clostridium isolates, and 53 (15%) anaerobic cocci. Seventy-five patients died: 40 of these had B. fragilis group isolates (including B. fragilis, 28, and B. thetaiotaomicron, 8) and 21 had Clostridium organisms isolated.
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