Search

Objectives: The aim was to study the persistence and characteristics of Staphylococcus warneri strains resistant to quaternary ammonium compounds (QACs), including sequencing and analysis of two plasmids proved to carry the smr gene.Methods: During a 3.5 year period quarter milk samples were collected on three occasions from all lactating cows in a dairy herd. The samples were screened with regard to QAC-resistant bacteria using a selective medium. Thirty randomly selected QAC-resistant S. warneri were typed by PFGE and subjected to plasmid isolation and analysis followed by gene detection using PCR. Two smr-containing plasmids in S. warneri isolates were sequenced.Results: All isolates from the initial collection of quarter milk contained smr residing on a 5.8 kb plasmid (pSW174), which contained regions with high similarities to various plasmids, including pT181, pSK108 and pPI-2. The pT181-like sequence was flanked by 148 bp direct repeats, denoted ISLE49, with high similarity to previously reported sequences of ~148 bp, including ISLE39 flanking the insertion sequence IS257 in methicillin-resistant Staphylococcus aureus. All isolates from subsequent collections of quarter milk harboured a smaller smr-containing plasmid (pSW49). Sequence analyses revealed pSW49 (3552 bp) to be an in-part deleted version of pSW174 (5767 bp).Conclusions: The IS-associated elements found in this study may have a wider role in the integration and excision of DNA sequences in staphylococci than previously reported. The mosaic plasmid structure based on genetic elements of various origins contributes to further knowledge on the flexibility of smr-encoding plasmids. [ABSTRACT FROM AUTHOR]

Background. Chronic morphological changes in the kidney allograft predict long-term graft function, but there are few studies comparing different methods in assessing chronic lesions. In the present study, we evaluated allograft cortical interstitial fibrosis, and compared semiquantitative assessment with computerized image analysis of Sirius red-stained collagen in prediction of graft prognosis.Methods. Sections were obtained from a series of 1-year protocol living donor kidney graft biopsies (n = 33) and their corresponding baseline specimens (n = 32). At light microscopy, the biopsies were scored for interstitial fibrosis as a percentage of involved tubulointerstitium according to the Banff schema. Quantitation of cortical fractional interstitial fibrosis volume (Vint) was performed with computerized image analysis on coded sections stained with Sirius red. The results were correlated with kidney function at 810 years after transplantation, and with late graft loss.Results. There was a significant correlation between the semiquantitative and quantitative methods for measuring cortical interstitial fibrosis in all the biopsies (n = 65, percentage area vs Vint: R = 0.439, P = 0.0003). The correlation further improved when analysing the baseline specimens separately (n = 32, R = 0.704, P<0.0001) and was still significant, but less precise for the 1-year biopsies (n = 33, R = 0.384, P = 0.0274). One-year semiquantitative fibrosis (percentage area) was correlated to serum creatinine at 810 years (P = 0.010) and to late graft loss (P = 0.0445). The 1-year Vint values for interstitial fibrosis showed a similar trend but did not reach statistical significance in prediction of long-term graft function.Conclusions. Image analysis quantitation of interstitial collagen with Sirius red corresponded well to light microscopic semiquantitative assessment of interstitial fibrosis. In prediction of long-term graft function, the semiquantitative method was superior, indicating that accumulation of matrix molecules other than fibrillary collagens, oedema and inflammation are also important in graft prognosis. [ABSTRACT FROM AUTHOR]