Lactobacillus Species Identification, H ₂ O ₂ Production, and Antibiotic Resistance and Correlation with Human Clinical Status

Abstract

Lactobacilli recovered from the blood, cerebrospinal fluid, respiratory tract, and gut of 20 hospitalized immunocompromised septic patients were analyzed. Biochemical carbohydrate fermentation and total soluble cell protein profiles were used to identify the species. Hydrogen peroxide production was measured. Susceptibility to 19 antibiotics was tested by a diffusion method, and the MICs of benzylpenicillin, amoxicillin, imipenem, erythromycin, vancomycin, gentamicin, and levofloxacin were determined. A small number of species produced H2O2, and antibiotic susceptibilities were species related. Eighteen (90%) of the isolates wereL. rhamnosus, one was L. paracasei subsp. paracasei, and one was L. crispatus. L. rhamnosus, L. paracasei subsp. paracasei isolates, and the type strains were neither H2O2 producers nor vancomycin susceptible (MICs, ≥256 μg/ml). L. crispatus, as well as most of the type strains of lactobacilli which belong to the L. acidophilus group, was an H2O2 producer and vancomycin susceptible (MICs, <4 μg/ml).

Identification of lactic acid bacteria isolated from human blood cultures

“…This method, which has been used for reliable identification of different LAB species (e.g. Felten et al, 1999;Arpi et al, 2003) confirmed all the identifications obtained with biotyping as well as (GTG) 5 -PCR fingerprinting, and assigned the unknown strain CCM 7270 as representing Ln. pseudomesenteroides.…”

Safety of probiotics: translocation and infection

“…29 Of all the lactobacilli, L. rhamnosus strains have been isolated most frequently in cases of human sepsis (Table 2), raising the postulation that this Lactobacillus species may have a higher potential to translocate and can be more pathogenic than other species. 45,46 L. rhamnosus has been found to exacerbate intestinal inflammation and to translocate to different extraintestinal organs under conditions of extensive mucosal damage. 47 When L. rhamnosus PHLS A103/70, which had been isolated from patients with infective endocarditis, was injected into rabbits, lactobacilli were found in most of the rabbits tested at levels less than 10 3 cfu/ml of peripheral blood.…”

Incidence and antibiotic susceptibility of bacteriocin‐producing lactic acid bacteria from dairy products

“…According to the qualitative method of Felten et al (1999), LAB isolated were streaked on to a 20-mL MRS agar plate containing 5 mg of 3,39,5,59tetramethylbenzidine (TMB; Sigma Aldrich), a benzidine-like chromogenic substrate of peroxidase, and 0.20 mg of horseradish peroxidase (Sigma Aldrich). Peroxidase generates O 2 from any H 2 O 2 produced by the LAB, and the TMB stains the colonies blue in the presence of O 2 .…”

“…All strains were tested in triplicate. The Lactobacillus acidophilus ATCC4356 type strain was used as quality controls (Felten et al 1999).…”