Increased colonization of indwelling medical devices by quorum-sensing mutants of Staphylococcus epidermidis in vivo.

Infections with the leading nosocomial pathogen Staphylococcus epidermidis are characterized by biofilm development on indwelling medical devices. We demonstrate that the quorum-sensing regulator agr affects the biofilm development of S. epidermidis in an unexpected fashion and is likely involved in promoting biofilm detachment. An isogenic agr mutant showed increased biofilm development and colonization in a rabbit model. In addition, nonfunctional agr occurred more frequently among strains isolated from infections of joint prostheses. Lack of functionality was based on mutations, including insertion of an IS256 element. Relative to other bacterial pathogens, quorum sensing in S. epidermidis thus has a different role during biofilm development and biofilm-associated infection. Our results indicate that disabling agr likely enhances the success of S. epidermidis during infection of indwelling medical devices. The permanent elimination of quorum-sensing regulation used by S. epidermidis represents a surprising and unusual means to adapt to a certain environment and type of infection.

Vuong C ，Kocianova S ，Yao Y ，Carmody AB ，Otto M ... -  《JOURNAL OF INFECTIOUS DISEASES》

Role of the luxS quorum-sensing system in biofilm formation and virulence of Staphylococcus epidermidis.

Xu L ，Li H ，Vuong C ，Vadyvaloo V ，Wang J ，Yao Y ，Otto M ，Gao Q ... -  《-》

Quorum-sensing control of biofilm factors in Staphylococcus epidermidis.

Vuong C ，Gerke C ，Somerville GA ，Fischer ER ，Otto M ... -  《JOURNAL OF INFECTIOUS DISEASES》

Specificity grouping of the accessory gene regulator quorum-sensing system of Staphylococcus epidermidis is linked to infection.

Carmody AB ，Otto M 《ARCHIVES OF MICROBIOLOGY》

Comparison of Staphylococcus epidermidis isolated from prosthetic joint infections and commensal isolates in regard to antibiotic susceptibility, agr type, biofilm production, and epidemiology.

Staphylococcus epidermidis is the predominant bacterial species in the normal flora of the human skin and superficial mucosal membranes. However, it has also emerged as the most important pathogen in infections related to foreign-body materials, such as prosthetic joints and heart valves. The aims of this study were to characterise S. epidermidis isolated from prosthetic joint infections (PJI; n=61) and commensal isolates from healthy individuals (n=24) in regard to antimicrobial sensitivity, agr type, hld gene presence, biofilm production including presence of ica and aap genes involved in the biofilm formation process and epidemiology using both phenotypic (the PhenePlate-system) and genotypic [multilocus sequence typing (MLST)] methods. Among the PJI isolates, the majority (67%) were multidrug-resistant. Two major clusters of PJI isolates could be identified; 44% belonged to MLST sequence type (ST) 2, all but one were of agr type 1, and 31% were assigned ST215 and were of agr type 3. Of the commensal isolates, only one isolate was multidrug-resistant, and they were more molecular epidemiologically diverse with mainly MLST singletons and a maximum of 3 isolates assigned to the identical ST. Biofilm production was detected in 41% of the PJI isolates and 58% of the commensal isolates, with the aap gene (95%) more frequently detected than the ica genes (62%) in the biofilm-positive isolates. In conclusion, S. epidermidis isolated from PJIs and commensal isolates differed regarding antimicrobial sensitivity and molecular epidemiological typing using MLST, but not substantially in the distribution of agr types, biofilm production, or the presence of ica and aap genes.

Hellmark B ，Söderquist B ，Unemo M ，Nilsdotter-Augustinsson Å ... -  《-》