Intestinal Bacteria Translocate Into Experimental Intra-abdominal Abscesses

Experimental intra-abdominal abscesses were initiated by surgical implantation of a fibrin clot contaminated with either Bacteroides fragilis, Bacteroides thetaiotaomicron, or B fragilis—Escherichia coli. Seven days after surgery the numbers of bacteroides (per gram) in B fragilis and B thetaiotaomicron abscesses were typically log₁₀ 8.4 ± 0.5 (n = 6) and log₁₀ 6.4 ± 0.6 (n=4), respectively; B fragilis—E coli abscesses typically contained log₁₀ 8.9 ± 0.5 B fragilis and l og₁₀ 7.6 ± 0.6 E coli (n = 5). Of 38 B fragilis abscesses, 14 B fragilis—E coli abscesses, and nine B thetaiotaomicron abscesses, additional intestinal bacteria were recovered from 21 (55%), 13 (93%), and seven (89%) abscesses, respectively. The additional organisms, in decreasing order of frequency, were enterococci, E coli, staphylococci, α-streptococci, lactobacilli, and Proteus species in numbers ranging from 2.5 log₁₀ to 7.9 log₁₀ per gram of abscess. Histologic sections of contaminated abscesses adherent to the intestine, liver, or spleen revealed normal tissue histology and no breakdown of the abscess wall. Thus, intestinal bacteria translocated into intra-abdominal abscesses by a mechanism that did not appear to be surgical soilage.