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RS Microbiology
Respiratory System Microbiology - Virology of LRTI
Question | Answer |
---|---|
Important viral causes of LRTI: | Influenza Para-influenza Respiratory syncytial virus SARS MERS Human metapneumovirus (2001) common in comprised children and elderly persons |
Para influenza Viruses cause: | Croup (Acute Laryngotracheobronchitis),pneumonia in children, and common cold – like disease in adults |
5 subtypes for Para Influenza viruses: | 1, 2, 3, 4a and 4b |
Surface spikes on para influenza viruses consist of: | H, N and fusion proteins |
Transmission of Parainfluenza via: | Respiratory droplets |
Clinical findings of infection with parainfluenza: | Croup – Harsh cough – Inspiratory stridor – Hoarse voice Patients are usually afebrile. About 80% of patients exhibit runny nose |
Which other viruses can induce croup? | Influenza viruses RSV Measles and chickenpox |
Lab diagnosis: | Clinically for croup Cell culture isolation Immunoflurescence Antibody rising titre using HAI or ELISA |
Treatment for parainfluenza: | Nursing in plastic tents supplied with cool, moistened oxygen Severe respiratory obstruction may require endotracheal intubation followed by a tracheotomy |
RSV infections cause: | Pneumonia Bronchiolitis in infants |
RSV is a major nosocomial pathogen in: | Pediatric wards |
Transmission of RSV | Respiratory droplets and direct contact of contaminated hands with the nose or eye |
Incubation period is: | 3-6 days |
Syncytia form in which organ, in the case of RSV? | The lungs |
RSV is the most common cause of: | Severe lower respiratory disease in young infants 50-90% bronchiolitis 5-40% pneumonias |
In young children, RSV may cause: | Otitis media |
In older children and adults, RSV may cause: | Common cold like disease |
What is the effect of RSV infections in infants? | Febrile URTI Lower respiratory tract involvement Worsening cough Tachypnoea and dyspnoea Hyperinflation of lungs Cyanosis |
Risk groups for RSV infections: | Infants with congenital heart disease Infants with pulmonary disease Immunocompromised infants Nephrotic syndrome and cystic fibrosis |
Complications of RSV infections: | 1) Apnea 2) Alterations in pulmonary functions which may lead to chronic lung diseases later in life |
Laboratory diagnosis of RSV infection is done with: | Immunoflurescence on smears of respiratory secretions ELISA for detection of RSV antigens Isolation in cell culture (multinucleated giant cells or syncytia) Rise of antibody titer |
Characteristics of SARS-causing virus: | Enveloped virus, Replicates in cytoplasm of animal cells Single-strand 30 kb RNA genome First identified in Guangdong Province, China in 2002 Associated Coronavirus SARS-HCoV Replication in cytoplasm rather than nuclei |
Symptoms for SARS: | Initially: High fever of 38оC or higher, head and body aches, and malaise. Week Later: dry cough, difficulty breathing and severe diarrhea. Recovery: after 5 to 6 days |
Diagnostic tests for SARS: | Antivirals and steroids used for atypical pneumonia Lab tests: RT-PCR EIA ELISA |
Prevention: | Isolation Sterilization of area 3 possible Vaccines (whole-killed, adenovirus vector, or recombination spike protein |
What is MERS? | Middle East respiratory syndrome coronavirus |
MERS was first reported in: | Saudi Arabia |
Characteristics of MERS: | Positive-sense, single-stranded RNA virus of the genus Betacoronavirus |
MERS-CoV is distinct from | SARS coronavirus Common-cold coronavirus Betacoronaviruses (HCoV-OC43 and HCoV-HKU1) |
How does transmission of MERS occur? | Via respiratory secretions |
Metapneumovirus was first isolated in: | Nasophargyngeal aspirates from 28 children over a 20 year period |