Usefulness of a computerized expert system associated with systematic O-serotyping for the early detection of outbreaks of hospital acquired infections and for the presumptive antibiotic therapy of Pseudomonas aeruginosa infections.

Over a four-year period, the systematic O-serotyping of all Pseudomonas aeruginosa isolated in Hôpital de Rodez associated with the use of a computerized expert system, facilitated the early detection of two outbreaks of nosocomial infections with multiresistant serotype O:11 and multiresistant serotype O:12 P. aeruginosa respectively involving ten patients over 16 months and six patients over six months. Over this four-year period, serotype O:12 represented 14% of 404 clinical isolates of P. aeruginosa, and most isolates of this serotype were resistant to multiple antibiotics. Combination experiments showed that fosfomycin/amikacin together were active against 86% of O:12 isolates. Fosfomycin/amikacin might be considered as a therapeutic alternative to ceftazime/amikacin for the presumptive antipseudomonal therapy of serotype O:12 infections.