Participation of interferon type I during canine parvovirus infection.

Canine parvovirus (CPV) is a single-stranded DNA virus that causes severe and fatal gastrointestinal diseases in dogs. CPV has developed several strategies to evade innate immune response mediated by type I interferons (IFN-I) to achieve a successful infection. The aim of this work was to evaluate the capability of CVP-2c to evade the IFN-I mediated response in infected cells. To establish the role of this response, the gene expression of interferon ß (IFNß), IFIT1, IFIT3, MAVS, and STING were estimated in MDCK cells infected with CPV-2c. Viral replication and gene expression was evaluated by quantitative PCR, also, a treatment with IFN-I (interferon omega) was included to confirm the role of IFN-I during CPV infection. The results revealed that CPV-2c infection stimulates the expression of IFNß moderately, in these cells. Due to low IFNß induction, the IFIT1 and IFIT3 expression were also low, and therefore CPV-2c was able to replicate in these cells. However, when the cells were treated with exogenous IFN-I, the IFNß expression was higher, leading to an increased gene expression of IFIT1 and IFIT3, responsible for antiviral control. The overexpression of these proteins reduced the expression of NS1 and VP2 viral genes and hence viral replication. MAVS and STING expression on infected cells showed a mild increase compared to IFNß, suggesting that the viral infection could partially modify its expression. All results obtained in this study showed that during CPV-2c infection in MDCK cells, the IFNß expression was altered since this cytokine is one of the most critical factors for the control and inhibition of viral replication.

Higher prevalence of meticillin-resistant Staphylococcus aureus among dental students.

In order to test the hypothesis that more dental students are meticillin-resistant Staphylococcus aureus (MRSA) carriers than non-dental students, 100 dental students with five to six years of exposure to patients and 81 non-dental students were tested for nasal and pharyngeal MRSA carriage by polymerase chain reaction. All 181 students were clinically healthy and none had taken antibiotics. Significantly more dental students (20/100) carried MRSA than non-dental students (5/81) (odds ratio: 4.04; 95% confidence interval: 1.6-12.6; P = 0.0033). Also, more dental students' mobile phones (8/100) carried MRSA. All MRSA isolates were distinguished by pulsed-field gel electrophoresis from epidemiologically significant strains. The results suggest that dental students are occupationally exposed to MRSA.

Performance of culture media for the isolation and identification of Staphylococcus aureus from bovine mastitis.

Rapid isolation and identification of pathogens is a major goal of diagnostic microbiology. In order to isolate and identify Staphylococcus aureus, a number of authors have used a variety of selective and/or differential culture media. However, to date, there are no reports comparing the efficacy of selective and differential culture media for S. aureus isolation from bovine mastitis cases using the 16S rRNA (rrs) gene sequence as a gold standard test. In the present study, we evaluated the efficacy of four selective and/or differential culture media for the isolation of S. aureus from milk samples collected from cows suffering from bovine mastitis. Four hundred and forty isolates were obtained using salt-mannitol agar (SMA, Bioxon), Staphylococcus-110 agar (S110, Bioxon), CHROMAgar Staph aureus (CSA, BD-BBL) and sheep's blood agar (SBA, BD-BBL). All bacterial isolates were identified by their typical colony morphology in the respective media, by secondary tests (for coagulase and ß-haemolysis) and by partial 16S rRNA (rrs) gene sequencing as a gold standard test. Sensitivity, positive predictive and negative predictive values were higher for SMA (86.96, 52.63 and 95.95%, respectively) compared with S110 (70.00, 23.73 and 90.91%, respectively), CSA (69.23, 28.13 and 95.74%, respectively) and SBA (68.75, 37.93 and 89.58%, respectively) while specificity values were similar for all media. Data indicated that the use of culture media for S. aureus isolation combined with determination of coagulase activity and haemolysis as secondary tests improved accuracy of the identification and was in accordance with rrs gene sequence-analysis compared with the use of the culture media alone.

Frequency of IS1-mediated molecular events in different members of the family Enterobacteriaceae.

The numbers of chromosomal copies of the insertion sequence IS1 in strains of Salmonella typhimurium (0 to 8 copies), Shigella sonnei (56 copies), and Shigella flexneri (41 copies) isolated in Mexico City, Mexico, were similar to those reported for these genera isolated in other countries. Of the 11 Shigella strains studied, all carried several small plasmids; however, in only one of these strains did a small plasmid contain IS1, IS1 recombination, cointegrate formation mediated by IS1 or by the IS1-flanked transposon Tn9, and transposition of Tn9 occurred at a higher frequency in S. typhimurium than in either Escherichia coli or S. sonnei strains. The frequencies of IS1 recombination in S. typhimurium strains containing either zero or eight copies of IS1 were similar.