The Relationship Between IcaA,icaD Gene Expression And Slime Formation In Staphylococcus Epidermidis

Staphylococcus epidermidis (S.E.) is an ordinary flora living in human skin and mucousmembrane. Looked through a microscope, it is a G staining positive coccus cocciresembling grape cluster. In blood agar it appears to be medium-sized moist opaquecolonies, with smooth surface and neat edge, and mostly white. It is opportunistpathogenic, and nonpathogenic under normal circumstances. Since medical implantusage is on the rise for modern medical technology, S.E. has been turning into a vitalnosocomial pathogen. The slime produced by the bacterium is Extracellular SlimeSubstance which may adhere to the host body and make bacteria difficult to be clearedand consequently causes infections or even causes acute exacerbation of chronicinfection or delayed healing. It can also wrap bacteria so that they can be protectedagainst antibiotics, thereby pathogenicity enhances and prone to bacterial drugresistance. Therefore, we attempt to interfere the generation of substrate, block thebacterial signal generation and transmission, and change the inner chemicalenvironment of bacterial biofilm (BBF) as well as effecting gene expression, so as toblock the polysaccharide-intercellular-adhesin (PIA) and slime production, thereby toreduce infection and drug resistance. Herein ica operon is the molecular basis of thesynthesis of PIA and has critical influence on slime production. It is of greatsignificance to study the influential factors on the blocking process of slime productionthereby to provide clinical guide on the effective control of infection and antibioticresistance. ObjectivesTo study the relationship between icaA and icaD gene expression and slime formatio-nin Staphylococcus epidermidis from ICU.MethodsCollect non-recurring separation of62strains of Staphylococcus epidermidis from theIntensive care unit of Anhui Provincial Hospital, from September,2009to December,2010. Among the62strains of Staphylococcus epidermidis,16strains were derivedfrom blood, tracheal secretions (tracheotomy or intubation sucked out sputum)33strains,6strains from venous catheter (tip of subclavian vein catheter), drainage fluid of3strains, urine (middle of clean urine), and wound secretion for2strains each. Andthese were diagnosed as bacteremia, Lower respiratory infections, Catheter-relatedbloodstream infections, severe pancreatitis, Urinary tract infections and skin structureinfections.Slime-forming ability was tested on congo red agar plates and icaA, icaD gene expres-sion were detected by PCR in62strains of S. epidermidis isolated from ICU. It adoptsstatistic solution of SPSS13.0software and chi square test for counting data.Results1. Among62strains of Staphylococcus epidermidis, icaA gene positive expression ratewas46.8%, the icaD gene positive expression rate of50.0%,all positive rate of bothicaA and icaD gene expresstions was37.1%,the negative rate of both icaA and icaDgene expressions was40.3%. Among the36non slime S.E strains, the positive ratesof icaA and icaD gene were19.4%and33.3%; all positive rate of both icaA and icaD gene expression was16.7%, all negative rate of both icaA and icaD geneexpressions was63.9%; among the26strains of slime producing Staphylococcusepidermidis, all positive rate of both icaA and icaD gene expressions was65.4%, allnegative rate of both icaA and icaD genes expressions was7.7%.2. Among the62strains of Staphylococcus epidermidis, there were36strains of nonslime production epidermidis, taking up58.1%; and26strains of slime productionepidermidis, taking up41.9%3. For those Staphylococcus epidermidis producing slimes, positive expression rate oficaA, icaD genes were high, all positive expression rate of icaA and icaD geneswere also high, significantly higher than the non-production slime strains (P <0.01,the difference was statistically significant); the icaA, icaD, negative gene expressionrate was low, significantly lower than non-production slime strains (P <0.01, thedifference was statistically significant); at the same time, not all slime-producingStaphylococcus epidermidis strains of icaA and (or) icaD gene were in positiveexpression, among slime-producing strains, the positive gene expression rate oficaA and icaD was not statistically significant.Conclusion1. icaA, icaD gene expression has an important influence on the slime production ofStaphylococcus epidermidis.2. There is no distinction between the slime production abilities of icaA and icaD geneexpression of Staphylococcus epidermidis.3. icaA, icaD gene expression is not the only factor to influence the slime production.