Analysis of the autoagglutination phenomenon, serogroup and hydrophobicity as virulence markers in mesophilic aeromonads isolated from stool cultures.

The autoagglutination phenomenon (AA) was studied in 71 strains of mesophilic aeromonads isolated from stool cultures of patients with acute diarrhea (28 Aeromonas hydrophila, 20 Aeromonas sobria, and 23 Aeromonas caviae). Two phenotypes were considered in the AA+ strains: SP+ (self-pelleting) and PAB+ (precipitation after boiling). Serogrouping of the strains was performed only with the 0:11 serum. Other properties studied were agglutination with acriflavine (Acr) and crystal violet uptake (CVB). Phenotype AA+ was found in 29.5% of the strains; 7% of these AA+ strains exhibited the SP+ PAB+ pattern and 22.5% the SP- PAB+ pattern. The species Aeromonas hydrophila comprised the highest proportion (28.5%), and Aeromonas caviae the lowest (13%). Fifty percent of the PAB+ strains of Aeromonas hydrophila and Aeromonas sobria belonged to serotype 0:11. None of the PAB+ strains of Aeromonas caviae belonged to this serotype. 8.4% of the strains were Acr+ and 23.9% CVB+.