Phenotypic and genotypic evaluation of slime production by conventional and molecular microbiological techniques.
Twenty-nine staphylococcal isolates from different clinical samples were tested for slime production: phenotypic characterization was carried out using Christensen test (tube test) and Congo red agar plate test (CRA plate test), while the presence and expression of icaA and icaD genes were evaluated by real-time PCR. In 79.3% of studied strains there was a concordance between slime production and presence of icaA and icaD genes, and between lack of slime production and absence of both or only one of the tested genes. In four of five strains where positive phenotype was not associated with the presence of ica genes, gene co-expression (evaluated by mRNA determination) was lacking, while in only a case out of five, there was the presence of transcripts without phenotype. Our study, for the first time, introduces real-time PCR for the detection of both icaA and icaD genes and their mRNA and, furthermore, addresses the relationship between slime phenotype absence and mRNA expression, in clinical isolates of coagulase-negative staphylococci.
Liberto
Maria Carla
MC
Department of Medical Sciences, Institute of Microbiology, University Magna Graecia, Catanzaro, Italy.
Matera
Giovanni
G
Quirino
Angela
A
Lamberti
Angelo Giuseppe
AG
Capicotto
Renata
R
Puccio
Rossana
R
Barreca
Giorgio Settimo
GS
Focà
Emanuele
E
Cascio
Antonio
A
Focà
Alfredo
A
D016667:Bacterial Capsules / Q000737:chemistry / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001431:Bacteriological Techniques / Q000379:methods*; D005838:Genotype; D006801:Humans; D010641:Phenotype; D016133:Polymerase Chain Reaction / Q000379:methods*; D013194:Staining and Labeling / Q000379:methods; D013203:Staphylococcal Infections / Q000382:microbiology*; D013210:Staphylococcus / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*
D001426:Bacterial Proteins