J. Med Microbiol. Vol. 43 ( 1995). 92-98 0 1995 The Pathological Society of Great Britain and Ireland CLINICAL ANAEROBIC MICROB I0 LOGY Bacteroides infections in children 1. BROOK Department of Pediatrics, Georgetown University School of Medicine, Washington, DC, USA Summary. From 1974 to 1990, 336 Bacteroides isolates were obtained from 312 specimens from 274 patients. They comprised 180 (54%) B. fragilis isolates, 55 (16%) B. theta- iotaomicron, 36 (1 1 %) B. culgatus, 34 (10 %) B. distasonis, 21 (6 %) B. ovatus and 10 (3 %) B. unzformis. Infections in 253 (92 Yo) patients were polymicrobial, but in 21 (8 ”0) children, a Bacteroides sp. was isolated in pure culture. Most Bhcteroides isolates were from peritoneal fluid (1 14)’ abscesses (1 lo), wound infections (20), blood cultures (10) and from patients with pneumonia (14) or chronic otitis media (8). Predisposing conditions were present in 145 (53 %) children ; these were previous surgery (46), trauma (28), malignancy (2 I), prematurity (19), immunodeficiency (18), steroid therapy (12) foreign body (lo), diabetes (9) and sickle cell disease (7). The micro-organisms isolated most commonly mixed with Bacteroides spp. were anaerobic cocci (221), Escherichia coli (122), Fusobacteriurn spp. (38) and Clostridium spp. (30). All patients received antimicrobial therapy in conjunction with surgical drainage or correction of pathology in 197 (72 Oh) cases. All but 12 (5O/O) patients recovered. These data illustrate the importance of Bacteroides spp. in infections in children. Introduction have been published before in articles describing the role of anaerobic bacteria in various paediatric The species of Bacteroidaceae that occur with infections,’ but cases not previously presented are also greatest frequency in anaerobic infections in children, included and the unique nature of bacteroides as they do in adults, belong to the genus Bacteroides. infections in children is emphasised. These micro-organisms are resistant to penicillins by virtue of P-lactamase production and by other un- Patients and methods known mechanisms.’ They were formerly classified as five subspecies of B. .fragilis (ss. fragilis, ss. distasonis, Pa tients ss. oratus, ss. thetaiotaonzicron and ss. culgatus) and were reclassified in 1976 into distinct species on the The children included in this review were studied by basis of DNA homology studies,’ and then became the the author between June 1974 and June 1990. They only species remaining in the genus Bacteroides sensu were seen in the following hospitals: University of stricto in 1990.3 B. -fragilis is the anaerobe most California Medical Center, Los Angeles County Medi- frequently isolated from clinical infections. cal Center and Serra Memorial Hospital in Los Recognition of the role of Bacteroides spp. in Angeles, CA ; Children’s Hospital National Medical paediatric infection has become more important in Center and South-East Medical Center in Washington, recent years because of their increased resistance to DC ; and National Naval Medical Center in Bethesda, some commonly used antimicrobial agents that were MD. Records from the clinical microbiology lab- previously very effective against them,* e.g., clinda- oratory were reviewed to identify patients with mycin. cephalosporins, metronidazole and chloram- bacteroides infections. The available case histories of phenicol.4 all patients from whom Bacteroides spp. had been This retrospective review summarises my experience isolated were reviewed to ascertain the presence and of the isolation of Bacteroides spp. from infections in site of infection, associated micro-organisms, under- children during a period of 16 years. Some of the data lying disease processes, and possible predisposing or associated conditions. Receixed 31 Ma) 1994: revised version received 8 Feb. 1995; accepted 9 Feb. 1995. Microbiological exam in at ion Correspondence should be sent to Professor I. Brook, PO Box 70417. Chev) Chse. MD 20813-0412, USA. Only specimens that were properly collected without 92 BACTEROIDES INFECTIONS IN CHILDREN 93 contamination by the normal skin or mucosal surface Bacteroides isolates flora and submitted in transport media appropriate for anaerobic bacteriological investigation were accepted The 336 Bacteroides isolates comprised 180 (54 "/O) by the microbiology laboratories. These were B. fragilis, 55 (16 %) B. thetaiotaomicron, 36 (1 1 YO)B. specimens obtained during surgery or by aseptic needle vulgatus, 34 (10 YO)B. distasonis, 21 (6 YO)B. ovatus and or biopsy aspiration of abscesses or fluid from body 10 (3 YO)B. uniformis (tables I and 11). Infections were cavities. Lung aspirates were obtained by transtracheal polymicrobial in 253 (92 YO)patients, but in 21 (8 YO) aspiration or biopsy. Urine was collected by supra- children, Bacteroides spp. were isolated in pure culture pubic aspiration. When possible, pus and fluids were (table 111). collected and transported in syringes. Most specimens, There were 749 other bacterial isolates with the except blood, were submitted on a Port-A-Cul trans- Bacteroides spp. in the 290 specimens from mixed port swab or in liquid systems (BBL, Cockeysville, infection; 429 of these were anaerobes and 320 were MD, USA). However, precise records of the transport facultative or aerobic species. The number of isolates media used were not available. Blood was collected in the mixed cultures was 2-7 (average 2-6 isolates/ aseptically from patients suspected of having specimen, 1.5 anaerobes and 1.1 facultative or aerobic). bacteraemia and was inoculated (10 YOv/v) into one The micro-organisms isolated most commonly with bottle each of two commercially produced broth Bacteroides spp. were anaerobic cocci (21 1 isolates), media, both under vacuum and with CO, 5% in the Escherichia coli (122), Fusobacterium spp. (40) and atmosphere. The sources of blood-culture media Clostridium spp. (31). Most E. coli and Clostridium varied during the period of review. spp. were isolated with Bacteroides spp. from intra- Specimens were inoculated on to pre-reduced vit- abdominal infections, and skin and soft tissue amin K1-enriched Brucella Blood Agar (BBL), blood infections around the rectal area. Most pigmented agar with kanamycin (75 mg/L) and vancomycin Prevotella and Porphyromonas isolates were from head (7.5 mg/L), and blood agar with colistin sulphate and neck infections. (0.01 mg/L) and nalidixic acid (50 mg/L), and into Most Bacteroides isolates were from peritoneal fluid an enriched thioglycolate broth containing haemin specimens (1 14 isolates, 34 YO),abscesses (1 10, 33 YO), (5 mg/L) and vitamin K (0.1 mg/L). The cultures were wounds (29,9 YO),pneumonia (14,4 YO),blood cultures incubated in GasPak jars (BBL) and examined after 48 (1 3,4 %), decubitus ulcers (10, 3 %) and chronic otitis and 96 h6. Plates that showed any growth were held media (8, 2%). until the micro-organisms had been identified. All cultures that showed no growth were held for at least Types of infections 5 days. Micro-organisms were identified by the API anaerobic system (Analytab Products, Plainview, NY, Peritonitis. The 114 peritoneal isolates of Bac- USA). When complete identification was not possible teroides spp. were from 108 children and were mixed by this method, other carbohydrate tests (Scott with other bacteria, mostly Peptostreptococcus spp. Laboratories, Fiskeville, RI, USA) and gas-liquid (96 isolates) and E. coli (65), but also Fusobacterium chromatography6 were performed as needed to spp. (23), group D streptococci (1 9), Eubacterium spp. identify the organisms. The criteria for identification (17) and Clostridium spp. (14). In 79 of the children, were according to guidelines published previo~sly.~3' peritonitis was associated with a ruptured appendix, nine cases followed trauma, and 10 rupture of a viscus. Abscesses. Of the 321 specimens from abscesses, 101 Results (32 O/O) yielded a growth of Bacteroides spp. (table 11). The most common abscesses from which the Patients Bacteroides spp. were isolated were abdominal (23 From a total of 1658 specimens examined for isolates), perirectal(14), pilonidal(l2) and subphrenic anaerobic bacteria, 336 Bacteroides strains were iso- (9). The most common other organisms in these lated from 312 (20%) specimens obtained from 274 abscesses were E. coli and Peptostreptococcus spp. patients. Clinical records were not available for review from another 18 patients; these were not included in Wound infections. The 29 isolates from wounds were the final analysis. Patients' ages ranged from one day from post-surgical infection of the abdomen (13 to 17.5 years (mean 7 years 9 months); 164 were male isolates), head and neck (six) and rectal area (five). In and 110 female. Predisposing or underlying conditions all cases, the Bacteroides isolates were mixed with were present in 145 (53%) of the patients. A single other bacteria-E. coli (eight isolates), enterococci underlying condition was noted in 120 cases, and two (four) and Staphylococcus aureus (four). The 10 conditions were recorded in 25 ; these conditions were isolates from decubitus ulcers were from ulcers of the previous surgery (46), trauma (28), malignancy (2 l), buttocks (four isolates), lower extremities (three) and prematurity (19), immunodeficiency (18), steroid head (three); all were mixed with other micro-organ- therapy (12), presence of a foreign body (lo), diabetes isms-Peptostreptococcus spp. (eight isolates), E. coli (9) and sickle cell disease (7). (four), S. aureus (three) and Clostridium spp. (two). 94 LBROOK Table I. Bacteroides isolates from 3 12 specimens from 274 children Number of specimens Number of Bacteroides isolates Type of infection B. B. thetaiota- omicron uniformis Peritoneal fluid 115 108 114 63 5 9 11 16 10 Abscess 321 101 2 110 61 11 13 6 19 Wounds 75 24 29 13 4 2 3 7 Decubitus ulcers 58 9 10 4 2 2 2 Omphalitis 25 6 7 4 1 2 Burn 180 5 5 4 1 Bites, human 18 1 1 1 Blood 334 13 12 13 10 1 2 Ear: mastoiditis 24 3 3 1 2 otitis. chronic 94 8 8 4 3 otitis, cholesteatoma 38 6 6 3 1 1 Pneumonia 80 13 3 14 4 3 7 Empyema 72 7 3 7 3 1 3 Sinusitis, chronic 45 1 1 1 Osteomyelitis 26 3 4 2 1 1 Conjunctivitis 148 1 1 1 1 Urinary tract infection 5 3 1 3 2 1 Total 1658 312 22 336 180 34 36 21 55 10 Table 11.