Rapid identification of Streptococcus pyogenes by flow cytometry.

E Sahar; R Lamed; I Ofek

doi:10.1007/bf02029514

Home/Archive/PubMed

PubMed · 6349986

Rapid identification of Streptococcus pyogenes by flow cytometry.

E Sahar·R Lamed·I Ofek

View original source ↗Export metadata ↓

Abstract

Flow cytometry combined with immunofluorescence of Streptococcus pyogenes was used to assay bacteria suspended in buffer solution and in saliva derived from throat swabs of healthy volunteers. The method allowed the enumeration of as few as 5 X 10(3) and 5 X 10(4) CFU per milliliter of buffer and saliva respectively. Controls including Streptococcus salivarius instead of Streptococcus pyogenes or buffer instead of specific antibodies confirmed the specificity of the detection of Streptococcus pyogenes in the samples. The results suggest that flow cytometry may serve as a basis for an automated reliable method for the diagnosis of streptococcal infections.

Explore related subjects

Culture Media Flow Cytometry Fluorescent Antibody Technique Humans Immune Sera Saliva Streptococcus pyogenes Journal Article

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

E Sahar, R Lamed, I Ofek. 1983. Rapid identification of Streptococcus pyogenes by flow cytometry.. https://doi.org/10.1007/bf02029514

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2007

Daptomycin susceptibility of unusual gram-positive bacteria: comparison of results obtained by the Etest and the broth microdilution method.

MICs of daptomycin, linezolid, and vancomycin against 212 isolates, including Listeria monocytogenes and Pediococcus, Leuconostoc, Rhodococcus, and Nocardia spp., were determined by the broth microdilution method; daptomycin MICs were also determined by the Etest. Except with those for Leuconostoc spp., daptomycin Etest MICs showed >90% agreement with MICs obtained by the broth microdilution method.

Culture Media↗

PubMed2007

A novel ex vivo skin model to study the susceptibility of the dermatophyte Trichophyton rubrum to photodynamic treatment in different growth phases.

BACKGROUND: Dermatophytes are fungi that can cause infections of skin, hair and nails because of their ability to feed on keratin. Superficial mycoses are among the most prevalent infectious diseases worldwide. Two important restrictions of current therapeutic options are the recurrence of the infection and prolonged treatment. This is especially true for infections caused by Trichophyton rubrum, a widely distributed dermatophyte. The application of photosensitizers for treatment of fungal infections is, within the field of photodynamic treatment (PDT), relatively new. Recently, we demonstrated that the porphyrins 5,10,15-tris(4-methylpyridinium)-20-phenyl-[21H,23H]-porphine trichloride (Sylsens B) and deuteroporphyrin monomethylester (DP mme) were excellent photosensitizers towards T. rubrum when using red light. OBJECTIVES AND METHODS: To evaluate the photodynamic effectiveness of the porphyrins in a situation that mimics the clinical situation, we developed an ex vivo model using human stratum corneum. This model offers the possibility of applying PDT at different time points during the germination and subsequent development of T. rubrum microconidia. The model was used for two different incubation media, Dulbecco's modified Eagle medium (DMEM) and distilled water. RESULTS AND CONCLUSIONS: We demonstrated that the PDT susceptibility of T. rubrum depended on the time of PDT application after spore inoculation. A decrease in susceptibility was observed with increasing time of PDT application for both photosensitizers in DMEM. Changing the incubation medium to distilled water resulted in an increased fungicidal effect for Sylsens B and in a decreased effect for DP mme. We conclude that T. rubrum is susceptible to PDT in a situation that mimics the clinical situation. The fungicidal effect of PDT on fungal spores is of particular importance.

Culture Media↗

PubMed2007

Growth of probiotic lactobacilli in the presence of oleic acid enhances subsequent survival in gastric juice.

The effect of inclusion of various C18 fatty acids with 0-2 double bonds in either cis or trans configuration on Lactobacillus rhamnosus GG survival was analysed in simulated gastric juice at pH 2.5. The incorporation of Tween 80 (1 g l-1) in the growth media enhanced subsequent survival of stationary-phase cultures up to 1000-fold following 90 min acid exposure compared with controls grown without Tween 80. There was a significant (P<0.05) increase in bacterial content of oleic acid [C18:1 (9c), up to 55-fold] after growth of bacteria in MRS supplemented with Tween 80. The inclusion of various C18 fatty acids in the growth media revealed that only oleic and vaccenic acids [C18:1 (11t)] had protective effects on the survival of Lb. rhamnosus GG when exposed to the acidic environment. Comparative analysis with other lactobacilli indicated that all strains exhibited increased survival when grown in the presence of Tween 80. Further work with a neomycin-resistant mutant with 48% of the F0F1-ATPase activity of the parent indicated that the Tween 80 effect was independent of the complex. The mechanisms behind the effect of fatty acid protection were investigated and proton permeability assays showed that cultures grown in the presence of Tween 80 had higher extracellular pH than controls. Furthermore, there was a significant reduction of oleic acid and a significant increase in stearic acid (C18:0) (P<0.05) content of bacterial cells following exposure of Tween 80-supplemented cultures to simulated gastric juice. Overall, the data suggest that probiotic lactobacilli can use an exogenous oleic acid source to increase their acid survival and the underlying mechanism most likely involves the ability of increased membrane oleic acid to be reduced by H+ to stearic acid.

Culture Media↗