Methicillin-resistant Staphylococcus aureus (MRSA) is an important and common pathogen causing community- and healthcare-associated infection. Culture methods were used for identification of MRSA for a long period of time, however it spends a lot of time on incubation and 1 to 2 days is needed to obtain the identification and antibiogram. Molecular tests were developed in the past decades and different genes were used. In this study a Staphylococcus aureus-specific gene, sau gene was designed and accompanied with mecA gene to detect the presence of MRSA in 322 nasal swabs from Tuen Mun Hospital. To evaluate the performance of in-house RT-PCR, samples were run in parallel with LightCycler? MRSA Advanced test and BBLTM CHROMagar? MRSA. 75 (23%) of samples were MRSA positive. The sensitivities and specificities of in-house RT-PCR and LightCycler? MRSA Advanced test were 76.7%/ 89.2% and 87.8%/ 96.6% respectively. The mean processing time for a batch of 32 samples by CHROMagar, in-house RT-PCR and LightCycler? MRSA Advanced test were 48.9 hours, 134.4 mins and 149.8 mins. In-house RT-PCR showed comparable performance and short turnaround time. sau gene can be used with mecA gene for the detection of MRSA in nasal swab. / published_or_final_version / Medicine / Master / Master of Medical Sciences

No description available.

Viable bacteria have been found on environmental surfaces, including washed and unwashed clothing, and places that come into contact with laundry. Under certain conditions, clothing contaminated with pathogenic organisms may present a health risk to the laundry handler. This research project focused on i) evaluating Staphylococcus aureus and MRSA survival using front-load and top-load washing machines; ii) determining relative microbial levels on new, disposable, laundered and unlaundered hospital scrubs; iii) characterizing the relative hygiene of public and apartment laundromat surfaces; and iv) developing a quantitative risk assessment for laundry handlers.Standard microbial evaluation techniques were used to identify and quantify a variety of microorganisms on fabrics and environmental surfaces, including HPC bacteria, S. aureus, MRSA, total coliforms and Escherichia coli. S. aureus and MRSA were exclusively used during evaluation of bacteria reduction levels achieved by front- and top-load washers.Results from this research indicate:i) Washing in either a top- or front-load washer affords a 5 - 6 log10 reduction of S. aureus and MRSA when detergent is used. If complete drying and/or bleach are also employed, a 6 - 7 log10 reduction is achieved and few organisms remain.ii) Bacteria cross-contamination of other fabrics within a laundry load is common for both types of washers and between loads on the interior of top-load washers.iii) Significantly fewer bacteria (p=0.044) were detected on hospital-laundered scrubs than on home-laundered scrubs.iv) Laundromat surfaces can be contaminated with substantial numbers of bacteria and the potential exists for transfer of bacteria from a past user to the next laundromat patron.v) The risk of acquiring a S. aureus infection after handling unwashed laundry contaminated with an initial S. aureus level of 106 CFU/cm2 was estimated to be 0.59 infections per person per year. The estimated risk became negligible if handling washed laundry.

No description available.

Surgical site infections (SSIs) are an emerging cause of increased morbidity, mortality, and treatment cost, in veterinary medicine. Medical records were searched to evaluate for associations that could increase the risk of developing SSIs. Logistic regression was used to analyze the risk factors statistically, to determine their influence on SSI risk. An SSI incidence rate of 3.0% was found in this study for all small animal surgical procedures performed from September 2010 to July 2011, with implants, hypotension and surgical classification associated with increased likelihood of SSI. Active surveillance is crucial for the development of methods to prevent SSI’s. Biofilms contribute to the antimicrobial resistance properties commonly found in bacteria such as methicillin-resistant Staphylococcus pseudintermedius, which is found in canines. An enzyme known as DispersinB was studied to assess its effect on biofilm formation and degradation. DispersinB prevented the formation and eradicated biofilm in vitro. In vivo testing is required to further assess the effects of DispersinB. / Ontario Veterinary College Pet Trust, Canadian Institutes of Health Research, Kane Biotchech

S. aureus 1054. The recombination occurs by a novel method. The data show that pSl or pΔD contribute the site for recombination and that the gene(s) for the protein(s) involved in recombination are encoded on pOX1054 or the 1054 chromosome. Integration of the plasmids into the chromosome of 1054 was not detected.

Staphylococcus aureus protease V8 (SPV8), also known as Endoproteinase Glu-C (EC 3.4.21.19), is an enzyme isolated from the bacteria Staphylococcus aureus. This unusual enzyme has been found to cleave specifically at glutamyl and aspartyl peptide bonds and has been used as a tool in the preparation of protein substrates for amino acid sequence analysis. SPV8 has been reported to show some stability toward various denaturants (Drapeau, G.R. (1977) Methods in Enzymology_, 47:189-191). In order to more adequately assess the denaturant stability of SPV8, the effect of guanidine hydrochloride (HC1), a common protein denaturant, on the proteolytic action of SPV8 was studied. The extent of cleavage of the glutamyl peptide bond in adrenocorticotropic hormone 1-10 (ACTH 1-10) was found to decrease with increasing concentrations of guanidine HC1.At 22°C in the presence of 3.0 M guanidine HCl, only 25% of SPV8's proteolytic activity was retained. In the presence of 4.0, 5.0, or 6.0 M guanidine HC1, virtually all proteolytic activity toward the glutamyl bond of ACTH 1-10 was lost, presumably due to the inactivation of the protease by denaturation or increased autolysis mediated by the guanidine HC1. At temperatures above 22°C, SPV8 was more susceptible to inactivation by guanidine HC1. Thus SPV8 appears to retain some proteolytic activity in the presence of guanidine HC1, but only at concentrations less than 4.0 M. There was no difference in the proteolytic activity of SPV8 toward the glutamyl peptide bond of ACTH 1-10 when incubation was carried out in ammonium bicarbonate buffer (pH 7.80), phosphate buffer (pH 7.80), or Tris-HC1 buffer (pH 7.80). The presence of 1 mM calcium chloride in the 3.0 M guanidine HC1/phosphate buffer solution enhanced the enzymatic action of SPV8. The presence of 1 mM calcium chloride in Tris-HC1 buffer (pH 7.80) does not effect the proteolytic activity of SPV8 at 22°C. However, there was slight reduction in SPV8's enzymatic action toward ACTH 1-10 when the 1 mM calcium chloride was present in the 3.0 M guanidine HC1/ammonium bicarbonate buffer (pH 7.80) solution. / Department of Chemistry

The treatment of Staphylococcus aureus bloodstream infections (SABSI) remains a major challenge. With an emphasis on complicated methicillin–sensitive S. aureus (MSSA), a comprehensive analysis of initial antibiotic treatment was conducted. The influence of treatment gaps on clinical outcomes were examined. Strategies were developed to improve the use of available antibiotics. Patient- and infection-related variables predictive for end-of-treatment failure included higher Charlson Comorbidity Index and healthcare-associated infection. Treatment variables of shorter duration of optimal targeted, shorter duration of optimal or adequate and lower TSE score were also predictive for end-of-treatment failure when tested separately in their own models. Strategies to optimize the treatment of complicated MSSA BSI at minimum should include: 1) Initiating at least an adequate therapy within 24 hours following the index blood culture draw and 2) Maintaining uninterrupted treatment, especially during the initial 7 days including at least 4 days of cloxacillin or cefazolin.

Background: Staphylococcus aureus (SA) infections are common and important within the hospital environment. The case fatality rate of invasive Staphylococcus aureus (SA) infections is between 20-40%. Whether the infection is due to methicillin resistant SA (MRSA) or methicillin sensitive SA (MSSA) may determine outcomes. Literature to date is inconclusive regarding whether antimicrobial resistance in SA affects patient outcomes. Host factors, infection-host interactions, and treatment-related factors may also influence case fatality. Objectives: The purpose of this study was to determine if patients with MRSA invasive infections were more likely to die than those with MSSA invasive infections, and what factors were associated with death. Methods: A retrospective matched case control study was designed, comparing cases of MRSA with controls of MSSA invasive disease from hospitals participating in the Canadian Nosocomial Infection Surveillance Program (CNISP). Two analyses were run: the first, to identify the variables associated with MRSA vs. MSSA infections, and the second, to determine the variables associated with death in invasive Staphylococcal aureus (S. aureus) infections. Backward logistic regression analysis was used for the MRSA vs. MSSA analysis and a hierarchical logistic regression model for assessment of risk factors for death. Results: In the logistic regression MRSA model the variables: recent prior use of antibiotics, Charlson Comorbidity Index score > 2 and not having received appropriate empiric antibiotics were associated with MRSA vs. MSSA infections. The hierarchical model identified older age, higher CCI scores, immunosuppression, bloodstream infection, septic shock, neurological dysfunction and not receiving appropriate empiric antibiotic as associated with death. MRSA infection was not more likely to be associated with increased mortality than MSSA infection. Those with a resistant infection (MRSA) however, were less likely to receive appropriate empiric antibiotic treatment. Conclusions: Appropriate empiric antibiotics are the most important and only modifiable risk factor identified. Elderly patients who are on immunosuppressive drugs and have chronic comorbid conditions need to be monitored and screened more often since they are more at risk for death than others.

Background: Staphylococcus aureus (SA) infections are common and important within the hospital environment. The case fatality rate of invasive Staphylococcus aureus (SA) infections is between 20-40%. Whether the infection is due to methicillin resistant SA (MRSA) or methicillin sensitive SA (MSSA) may determine outcomes. Literature to date is inconclusive regarding whether antimicrobial resistance in SA affects patient outcomes. Host factors, infection-host interactions, and treatment-related factors may also influence case fatality. Objectives: The purpose of this study was to determine if patients with MRSA invasive infections were more likely to die than those with MSSA invasive infections, and what factors were associated with death. Methods: A retrospective matched case control study was designed, comparing cases of MRSA with controls of MSSA invasive disease from hospitals participating in the Canadian Nosocomial Infection Surveillance Program (CNISP). Two analyses were run: the first, to identify the variables associated with MRSA vs. MSSA infections, and the second, to determine the variables associated with death in invasive Staphylococcal aureus (S. aureus) infections. Backward logistic regression analysis was used for the MRSA vs. MSSA analysis and a hierarchical logistic regression model for assessment of risk factors for death. Results: In the logistic regression MRSA model the variables: recent prior use of antibiotics, Charlson Comorbidity Index score > 2 and not having received appropriate empiric antibiotics were associated with MRSA vs. MSSA infections. The hierarchical model identified older age, higher CCI scores, immunosuppression, bloodstream infection, septic shock, neurological dysfunction and not receiving appropriate empiric antibiotic as associated with death. MRSA infection was not more likely to be associated with increased mortality than MSSA infection. Those with a resistant infection (MRSA) however, were less likely to receive appropriate empiric antibiotic treatment. Conclusions: Appropriate empiric antibiotics are the most important and only modifiable risk factor identified. Elderly patients who are on immunosuppressive drugs and have chronic comorbid conditions need to be monitored and screened more often since they are more at risk for death than others.