Evaluation of Mannitol Salt Agar for Detection of Oxacillin Resistance in Staphylococcus aureus by Disk Diffusion and Agar Screening

Mannitol salt agar was evaluated for detection of oxacillin resistance in 136 Staphylococcus aureus isolates. All mecA-positive isolates (n = 54) were correctly categorized as oxacillin resistant by the disk diffusion test (1-μg disk; zone diameter, <16 mm); the specificity was 97.6%. Agar screening (2 μg of oxacillin per ml) revealed a sensitivity of 98.1% and a specificity of 95.1%.     

Dextran sulphate sodium induces acute colitis and alters hepatic function in hamsters

Dextran sulphate sodium (DSS)-induced colitis in rodents is an experimental model for human inflammatory bowel disease (IBD). The aim of this study was to characterize the effect of DSS in hamster colon and liver. DSS (2-5%) was administrated in the drinking water for 4-6 days. Clinical symptoms were recorded daily, inflammatory and fatty acid-related metabolic markers were assessed in plasma, colon and liver. Six days of 3 or 5% DSS induced a severe wasting disease, whereas 2.5% DSS induced a colonic inflammation without severe systemic adverse effects. The systemic inflammatory response was characterized by an inverse production of albumin and the acute phase protein haptoglobin. The colonic inflammatory response was confined to the proximal colon, manifested by a high macroscopic inflammatory score, increased colon weight and expression of IL-1beta, IL-6 and iNOS, infiltration of inflammatory cells and epithelial disruption. In contrast, only a low/mild inflammatory response was observed in the distal colon of DSS-exposed hamsters. Significant hepatic-related metabolic alterations were also observed, with elevation of plasma triglycerides and increased liver expression of lipoprotein lipase and reduced expression of acyl-CoA oxidase and cytochrome P450A. Although liver weight was significantly reduced, no histopathological signs of inflammation or tissue damage were observed. In summary, hamsters exposed to 2.5% DSS for 6 days develop acute colitis resembling murine DSS-induced colitis. In addition, DSS-exposed hamster showed alterations in hepatic fatty acids metabolism resembling human IBD, suggesting that the model can potentially be used for target discovery and validation of hepatic-related metabolic alterations.     

Evaluation of the BBL Crystal MRSA ID System for detection of oxacillin resistance in Staphylococcus aureus.

AIMS: To evaluate the BBL Crystal MRSA ID System for detection of oxacillin resistance in Staphylococcus aureus. METHODS: 52 methicillin resistant S aureus (MRSA) from five different countries and 85 methicillin susceptible S aureus (MSSA) were included. The species was confirmed by tube coagulation and detection of the clumping factor using the Staphaurex Plus. Clonal non-identity of the MRSA isolates was shown by pulsed field gel electrophoresis. MIC values (oxacillin) were determined using the Etest. Polymerase chain reaction was carried out to detect the mecA gene. The BBL Crystal MRSA ID System was carried out according to the manufacturer's instructions. RESULTS: The BBL Crystal MRSA ID System showed fluorescence in 45 of 52 MRSA (sensitivity 86.5%; negative predicitive value 92.2%), and the specificity was 97.6% (positive predicitive value 95.7%). Two of seven MRSA that failed to show fluorescence had MIC values (oxacillin) of 4 mg/litre. CONCLUSIONS: The BBL Crystal MRSA ID System is a valuable test for detecting oxacillin resistance in S aureus. Its major advantage is the short time (4-5 hours) required to perform the test when organisms are grown on tryptic soy agar or sheep blood agar. Difficulties may arise in borderline resistant isolates.     

A 15-yr longitudinal study of xerostomia in a Swedish population of 50-yr-old subjects

The aim of this study was to determine the changes in prevalence of xerostomia in subjects from 50 to 65 yr of age. Questionnaires were sent to all subjects who were born in 1942 and were living in two Swedish counties in 1992, 1997, 2002, and 2007. The analyses focused on those who answered the questionnaires both in 1992 and in 2007. The response rate was 71.4% ( n  = 6,346) in 1992 and 73.1% ( n  =   6,078) in 2007. Of those who answered the questionnaire in 1992, 74.3% ( n  =   4,714) also responded in 2007. There was an almost linear increase in the prevalence of xerostomia at the four study time-points (i.e. when the subjects were 50, 55, 60, and 65 yr of age). Xerostomia was more prevalent at night than during the day. The pooled prevalence of night-time and daytime xerostomia was 6% at 50 yr of age and 15% at 65 yr of age, and it was higher in women than in men on both occasions. Logistic regression analyses showed that impaired health and smoking were significantly associated with daytime xerostomia but not with night-time xerostomia. Despite the increase in prevalence of xerostomia from 50 to 65 yr of age, there was considerable variation during the observation period. The incidence rate was 13% (507/4,015) and the disappearance rate was 42% (104/250) (dichotomized answers).     

Comparison of factors potentially related to the occurrence of dental erosion in high- and low-erosion groups

Soft drink intake, method of drinking, pH variations, plaque topography, and various salivary, microbial and clinical factors were compared in Saudi men with high (n = 10, mean = 20.5 yr) and low (n = 9, mean = 20.3 yr) dental erosion. pH-measurements were carried out with a microtouch electrode at six different intraoral locations after the subjects had consumed 330 ml of regular cola-type drink in their customary manner. The results showed that higher intake of cola-type drinks was more common in the high- (253 l yr(-1)) than in the low-erosion group (140 l yr(-1)). High erosion was associated with a method of drinking whereby the drink was kept in the mouth for a longer period (71 s vs. 40 s). pH after drinking did not differ between the groups for any of the six measuring sites. Plaque accumulation on the palatal surfaces of maxillary anterior teeth and urea concentration in unstimulated saliva were lower in high-erosion subjects. Aside from these, there were no differences in salivary and microbial factors between the groups. First molar cuppings, buccal cervical defects, and mouth breathing were more common in the high- than in the low-erosion group. In summary, consumption of cola-type drink, method of drinking, amount of palatal plaque on anterior teeth, and salivary urea concentration are factors associated with dental erosion.