Lactobacillus species identification, H2O2 production, and antibiotic resistance and correlation with human clinical status

Lactobacilli recovered from the blood, cerebrospinal fluid, respiratory tra ct, and gut of 20 hospitalized immunocompromised septic patients were analy zed. Biochemical carbohydrate fermentation and total soluble cell protein p rofiles were used to identify the species. Hydrogen peroxide production was measured. Susceptibility to 19 antibiotics was tested by a diffusion metho d, and the MICs of benzylpenicillin, amoxicillin, imipenem, erythromycin, v ancomycin, gentamicin, and levofloxacin were determined. A small number of species produced H2O2 and antibiotic susceptibilities were species related. Eighteen (90%) of the isolates were L. rhamnosus, one was L. paracasei sub sp. paracasei, and one was L. crispatus. L. rhamnosus, L. paracasei subsp. paracasei isolates, and the type strains were neither H2O2 producers nor va ncomycin susceptible (MICs, greater than or equal to 256 mu g/ml). L. crisp atus, as well as most of the type strains of lactobacilli which belong to t he L. acidophilus group, was an H2O2 producer and vancomycin susceptible (M ICs, <4 mu g/ml).