Dengue Virus IgM Serotyping by ELISA with Recombinant Mutant Envelope Proteins.

We developed an IgM-based ELISA that identifies the dengue virus serotype of recent infections. Dominant serotypes were detectable in 91.1% of samples from travelers and 86.5% of samples from residents of endemic regions; 97.1% corresponded to the serotype identified by PCR. This ELISA enables more accurate reporting of epidemiologic findings.

The relationship between the exposure to healthcare settings and colonization with methicillin-resistant Staphylococcus aureus among medical students.

INTRODUCTION: Medical students who engage in clinical learning in healthcare settings can be potential methicillin-resistant Staphylococcus aureus (MRSA) carriers. METHODS: This is a descriptive cross-sectional study having a follow-up approach. Three batches of medical students who were studying at the Faculty of Medicine and Allied Sciences, Rajarata University of Sri Lanka (1st, 3rd and 5th study years of MBBS course) were screened for nasal and axillary MRSA colonization. The first-year students were screened before and 6 months after clinical learning. The knowledge of the students about infection control was scored (percentage) using a questionnaire in the one week before and later one year after the hospital exposure. Data was compared using two-sample t test. RESULTS: The percentage of MRSA colonization was 6.36% (7/110) and 49.57% (59/119) before clinical exposure and after 2.5 years of exposure, respectively (p<0.012). The percentage of correct responses obtained by the students for the questionnaire about infection control was 28% and 66.9% one week before the exposure to the hospitals and one year after the exposure to the hospitals, consecutively. CONCLUSIONS: MRSA carriage was significantly associated with the time duration of the clinical training of the medical students. The knowledge of students about infection control was significantly inadequate one week before the hospital exposure and they have gained the knowledge only after being exposed to the hospitals.

Specific detection of dengue and Zika virus antibodies using envelope proteins with mutations in the conserved fusion loop.

Detection of antibodies is widely used for the diagnosis of infections with arthropod-borne flaviviruses including dengue (DENV) and Zika virus (ZIKV). Due to the emergence of ZIKV in areas endemic for DENV, massive co-circulation is observed and methods to specifically diagnose these infections and differentiate them from each other are mandatory. However, serological assays for flaviviruses in general, and for DENV and ZIKV in particular, are compromised by the high degree of similarities in their proteins which can lead to cross-reacting antibodies and false-positive test results. Cross-reacting flavivirus antibodies mainly target the highly conserved fusion loop (FL) domain in the viral envelope (E-) protein, and we and others have shown previously that recombinant E-proteins bearing FL-mutations strongly reduce cross-reactivity. Here we investigate whether such mutant E-proteins can be used to specifically detect antibodies against DENV and ZIKV in an ELISA-format. IgM antibodies against DENV and ZIKV virus were detected with 100% and 94.2% specificity and 90.7% and 87.5% sensitivity, respectively. For IgG the mutant E-proteins showed cross-reactivity, which was overcome by pre-incubation of the sera with the heterologous antigen. This resulted in specificities of 97.1% and 97.9% and in sensitivities of 100% and 100% for the DENV and ZIKV antigens, respectively. Our results suggest that E-proteins bearing mutations in the FL-domain have a high potential for the development of serological DENV and ZIKV tests with high specificity.

Anti-methicillin resistant Staphylococcus aureus activity, synergism with oxacillin and molecular docking studies of metronidazole-triazole hybrids.

MRSA causes 60-70% of Staphylococcus aureus infection in hospitals and it has developed resistance against the currently available drugs. Interestingly, a series of 35 metronidazole-triazole hybrids on screening against MRSA were found to be active. Compound 22 was found to be effective at 4 µg/mL concentration against nine strains of MRSA. The inhibitory activity was further enhanced upto 1 µg/mL when this compound was used in combination with oxacillin in 1:1 ratio. All the compounds were found to be non-toxic in THP-1 cell line upto a concentration of 50 µM. The time-kill kinetics studies suggested bacteriostatic nature of the compounds. In silico studies show that these compounds interact with Thr600, Ser598, Asn464, His583 and Tyr446 in the active site of PBP2a crystal structure from MRSA.