Making medical devices safer: impact of plastic and silicone oil on microbial biofilm formation.

BACKGROUND: Medical devices face the challenge of microbial biofilm attached to the surface. Ultimately, this may jeopardize the function of the device and increase the patient's risk of infection. However, reliable methods to prevent biofilm are lacking. AIM: To investigate the effect of silicone oil-coated polypropylene plastic, used in a new automatic urinometer, on biofilm formation; furthermore, to explore the impact of silicone oil viscosity and compare polypropylene with polystyrene, another common medical plastic. METHODS: Common pathogens, including extended-spectrum beta lactamase (ESBL) -producing and multi-drug-resistant bacteria, as well as Candida albicans, were investigated. Isogenic Escherichia coli strains deficient in the important biofilm forming factors curli, cellulose and type 1 fimbriae (fim D) were used to determine the possible mode of action by silicone oil. Clear flat-bottomed polypropylene or polystyrene wells were pretreated with either low- or medium-viscosity silicone oil and microbes were added. After 72 h, biofilm formation was quantified using crystal violet assay. FINDINGS: Silicone oil-coated polypropylene plastic surfaces, regardless of the oil viscosity, significantly inhibited biofilm formation of all tested Gram-negative and Gram-positive bacteria, including ESBL-producing and multi-drug resistant strains, as well as C. albicans. Silicone oil did not affect bacterial or candida growth and curli fimbriae were found to be the main target of silicone oil. Polypropylene plastic itself without oil had a better effect in preventing biofilm formation than polystyrene. CONCLUSION: These findings suggest a new strategy to decrease microbial biofilm formation, which may reduce hospital-acquired infections and prevent dysfunction of medical devices.

Association between vitamin D, antimicrobial peptides and urinary tract infection in infants and young children.

AIM: Vitamin D stimulates production of the endogenous antimicrobial peptides cathelicidin and ß-defensin-2, which are expressed in the urinary tract. We investigated vitamin D status and levels of cathelicidin and ß-defensin-2 and their association with urinary tract infection (UTI). METHODS: The study included 120 children under three years of age: 76 children with UTIs and 44 otherwise healthy children with congenital hydronephrosis. Serum 25-hydroxycholecalciferol levels were measured by direct competitive electro-chemiluminescence immunoassay, and plasma cathelicidin and ß-defensin-2 concentrations were analysed by enzyme-linked immunosorbent assay. RESULTS: We found that vitamin D insufficiency and deficiency are prevalent in young children (21%). Serum vitamin D levels negatively correlated with age and were significantly lower in girls. Levels of vitamin D positively correlated with levels of cathelicidin but not with ß-defensin-2. Low concentrations of vitamin D were associated with UTIs in girls, but we did not see any correlation with the recurrence of infection at one-year follow-up. CONCLUSION: Vitamin D deficiency is common and may prove to be a risk factor for UTIs especially in girls. We hypothesise that adequate supplementation with vitamin D may become a way to prevent first-time UTIs.

Statins influence epithelial expression of the anti-microbial peptide LL-37/hCAP-18 independently of the mevalonate pathway.

Anti-microbial resistance increases among bacterial pathogens and new therapeutic avenues needs to be explored. Boosting innate immune mechanisms could be one attractive alternative in the defence against infectious diseases. The cholesterol-lowering drugs, statins, have been demonstrated to also affect the immune system. Here we investigate the effect of statins on the expression of the human cathelicidin anti-microbial peptide (CAMP) LL-37/hCAP-18 [encoded by the CAMP gene] and explore the underlying mechanisms in four epithelial cell lines of different origin. Simvastatin induced CAMP expression in bladder epithelial cells telomerase-immortalized uroepithelial cells (TERT-NHUCs), intestinal cells HT-29 and keratinocytes HEKa, but not in airway epithelial cells A549. Gene induction in HEKa cells was reversible by mevalonate, while this effect was independent of the cholesterol biosynthesis pathway in TERT-NHUCs. Instead, inhibition of histone deacetylases by simvastatin seems to be involved. For HT-29 cells, both mechanisms may contribute. In addition, simvastatin increased transcription of the vitamin D-activating enzyme CYP27B1 which, in turn, may activate LL-37/hCAP-18 production. Taken together, simvastatin is able to promote the expression of LL-37/hCAP-18, but cell line-specific differences in efficacy and the involved signalling pathways exist.

Evaluation of a new chromogenic medium, chromID OXA-48, for recovery of carbapenemase-producing Enterobacteriaceae from patients at a university hospital in Turkey.

The purpose of this study was to evaluate a new chromogenic medium, chromID OXA-48, for the isolation of carbapenemase-producing Enterobacteriaceae (CPE) directly from rectal swabs. chromID CARBA and chromID OXA-48 are two chromogenic media that have been commercialized for the isolation of CPE directly from clinical samples. Both media were evaluated alongside a broth enrichment method recommended by the CDC for isolation of CPE, with rectal swabs from 302 unique hospitalized patients at the Hacettepe University Hospital, Ankara, Turkey. A total of 33 patients (11 %) were found to be colonized with CPE using a combination of all methods, and all CPE produced OXA-48 carbapenemase. Klebsiella pneumoniae was by far the most dominant species of CPE and was isolated from 31 patients. Culture on chromID OXA-48 offered the highest sensitivity (75.8 %) for detection of CPE compared with the other two methods (sensitivity for both other methods was 57.6 %) and also offered the highest specificity (99.3 %). However, a combination of methods (either chromID OXA-48 plus CDC method or chromID OXA-48 plus chromID CARBA) was necessary to achieve an acceptable sensitivity (90.9 %). For isolation of CPE, in a setting where OXA-48 carbapenemase is the dominant type of carbapenemase, chromID OXA-48 is a highly useful medium but using a combination of methods is optimal for adequate detection. The combined use of two chromogenic media offered acceptable sensitivity (90.9 %) and the highest specificity (98.5 %) and also allowed for isolation of CPE within 18-20 h.