RapidPresumptive Identification ofCitrobacter diversus as an AidinControlling Infections

During an outbreak ofneonatal meningitis causedbykanamycin-resistant Citrobacter diversus, a field procedure forpresumptive identification ofthe organismwas evaluated, andusing itresulted intheearly recognition ofpatients colonized bytheepidemic strain ofC.diversus. Rectal andnasopharyngeal specimenswere plated andincubated on MacConkey agar containing 10,ugof kanamycin per ml.After18h ofincubation, lactose-nonfermenting colonies present on theselective mediumwere picked andidentified 8hlater withthe following biochemical tests: indole, adonitol, dulcitol, citrate, andtriple sugariron agar.Thispresumptive identification ofC.diversus was later confirmed forall casesbyconventional testing with acomplete setofbiochemicals. In1week, 253 specimensfrompatients were processed withthis technique, and49strains ofC. diversus were identified. Therapid identification ofC.diversus andtransfer of carriers intoappropriate cohorts resulted ina 64%reduction intheprevalence of colonization. During someoutbreaks, laboratory proce- dures mustbedeveloped fortherapid detection oforganisms thatcausenosocomial infections. Thisisparticularly trueinoutbreaks ofrapidly progressive, potentially fatal diseases suchas neonatal meningitis. Someinfants may be asymptomatically infected orcolonized bythe epidemic strain andmayserve asareservoir for continued transmission ofthedisease. Recogniz- ingcolonized patients anddividing theminto cohorts areeffective aidsincontrolling out- breaks ofnosocomial infections. Conventional biochemical methods (4, 5)andmostcommercial ready-to-use kits(6-9) require 48to72h to identify bacterial strains belonging tothefamily Enterobacteriaceae. Presently, theMicro-ID