Rautio M. ^1,2, Saxén H. ³, Siitonen A. ², Nikku R. ³, Jousimies-Somer H. ¹
National Public Health Institute, ¹Anaerobe Reference Laboratory and ²Laboratory of Enteric Pathogens; ³Children's Hospital, University of Helsinki, Helsinki, Finland

The most common surgical emergency in childhood is acute appendicitis. The aim of the present investigation was to determine the bacterial composition of inflamed and normal appendices and to assess whether the floras differ according to histopatologic findings.
Tissue samples obtained at surgery from 41 children (16 F, 25 M; median age 12 yrs) with suspected acute appendicitis were examined histologically and in quantitative bacterial culture. The tissue specimens were ground and inoculated onto various selective and nonselective agar media and incubated in conducive atmospheric conditions, anaerobes for up to 14 d. Isolation and identification of organisms was performed by established methods.
The patients were grouped according to histopathological and clinical findings. In group 1(6 patients) appendices showed no inflammation. In group II (19 patients) acute inflammation involved only appendicular mucosa or submucosa. In group III (16 patients) diffuse suppurative gangrenous inflammation throughout the appendicular wall was present. Both aerobic and anaerobic species were isolated from 40/41 (98%) samples. In average, 13.9 different species or groups per specimen (10.4 anaerobes and 3.5 aerobes) were isolated. Bactera belonging to the B. fragills group (B. fragilis predominating; 73%) were the most frequently isolated anaerobic microorganisms (95%); distribution in all histology groups was similar. Other organisms frequently isolated in all groups were P. micros (66%), B. wadsworthia (63%), F. nucleatum (44%) and E. lentum (44%). P.intermedia or P nigrescens were isolated only from inflamed appendices; in group II, 8/19 (42%) and in group III, 9/16 (56%). The most common aerobic isolates were E. coli (88%) and S. milleri group organisms (59%).
Our results clearly demonstrate the presence of mixed aerobic and anaerobic flora in both normal and inflamed appendices in children, a finding in line with earlier reports in adults. The striking difference, however, was the complete lack of P. gingivalis in samples of children in all histology groups.