Lecture 1.1 - Introduction to the Infection Block PDF

Microorganisms causing disease: ◦Bacteria ◦Viruses ◦Fungi ◦Protozoa ◦Helminths (worms) ◦Prions Transmission of infection: ◦Person to person - influenza, SARS-CoV-2, EBV, HIV ◦Water - cholera, Hepatitis A ◦Food - E.coli, salmonella ◦Insects - Mal...

Microorganisms causing disease: ◦Bacteria ◦Viruses ◦Fungi ◦Protozoa ◦Helminths (worms) ◦Prions Transmission of infection: ◦Person to person - influenza, SARS-CoV-2, EBV, HIV ◦Water - cholera, Hepatitis A ◦Food - E.coli, salmonella ◦Insects - Malaria ◦Surface - MRSA History taking: ◦Importance of taking detailed history: ‣ Details of symptoms ‣ Time since first exposure ‣ Contacts (including sexual partners, animals) ‣ Environment (damp building, air conditioner, overcrowding) ‣ Food/drink ‣ Travel Markers of infection: ◦Rise in temperature (in some cases, temperature may go down) ‣ Interleukin 1 tells the brain to increase the temperature ◦General malaise (lethargy, body ache, head ache, loss of appetite, influenza etc) ◦Pain (general muscle pain in number of infections, abdominal pain in hepatitis, abdomen tender to touch etc) ◦Breathlessness (chest infection including pneumonia) ◦Local skin changes: ‣ Impetigo - blisters and sores on the skin ‣ Cellulitis - redness, heat, pain at the site of infection ‣ Necrotising faschilitis - deep skin infection ◦Cough: ‣ Dry cough e.g. whooping cough ‣ Productive cough - purulent sputum e.g. tuberculosis ◦Confusion - meningitis, sepsis etc General tests for infection: ◦White blood cell count - generally increase in infection BUT in some cases may decrease, for example CD4+ cells in HIV ‣ One cytokine is called interleukin 6 ◦C-reactive protein: ‣ Increase in C-reactive protein is a marker of infection and inflammation  Tests for cause of infection: ◦Bacteria: ‣ Direct microscopy after staining Gram stain (gram positive/gram negative bacteria) Acid fast stain (e.g. Mycobacteria tuberculosis) ‣ Blood culture (growth and identification) - looking for microorganisms Widely used to test for sepsis ‣ Swabs Direct staining and microscopy) Growth in appropriate medium ‣ Nucleic acid amplification/ PCR ‣ Antigen tests (used to test for hepatitis) ‣ Antibody tests ◦Viruses: ‣ Detection of antigens using Elisa/immunofluorescence ‣ Nucleic acid amplifications/PCR ‣ Antibody tests Investigations for infection: ◦X-ray (used a lot in chest infections and TB) ◦MRI scan ◦CT scan Public health and ethical issues: ◦Infection control: ‣ General public health measures: Masks, hand hygiene etc Infection control measures in hospitals and healthcare premises ‣ Quarantine: Effect on all areas of healthcare Effect on mental health ‣ Ethical issues: Ethical dilemmas around sexually transmitted diseases Who do you tell? When do you tell? Public health measures and freedom of citizens (SARS-CoV-2) Infection:  Vaccines: Passive immunisation: ◦Immunoglobulins from human serum - pooled human immunoglobulin or hyperimmune immunoglobulin ‣ Helpful in patients who have no immunity against that particular organism ‣ Does not generate memory - antibodies have to be made again ‣ Clears from the patient’s system in a few weeks to months Smallpox: Koch’s postulates: Poliomyelitis:  Development of vaccines against SARs-CoV-2: ◦Vaccines against SARS-CoV-2: examples of the main vaccines are Pfizer vaccine, Moderna vaccine, Oxford/AstraZeneca vaccine and Johnson and Johnson/Janssen vaccine ◦Different approaches: ‣ Lipid nanoparticle mRNA ‣ DNA ‣ Adjuvanted protein ‣ Inactivated virus particles ‣ Non-replicating viral vectors ◦More than 100 other vaccines were in early pre-clinical development Coronavirus vaccines in general use: ◦Pfizer/BioNTech COVID-19 vaccine ◦Pfizer/BioNTechbivalent COVID-19 vaccine ◦Moderna COVID-19 vaccine ◦Moderna bivalent COVID-19 vaccine ◦Novavax COVID-19 vaccine (Nuvaxovid) SARS: ◦SARS - severe acute respiratory syndrome is caused by the SARS coronavirus, known as SARS-CoV (bats to other animals and people) ‣ Respiratory problems, dry cough, fever, head and body aches ‣ Spread through respiratory droplets from coughs and sneezes. MERS: ◦Middle East respiratory syndrome MERS is caused by MERS coronavirus (MERS-CoV) - direct or indirect contact with infected dromedary camels ◦Symptoms include fever, cough and shortness of breath. Pneumonia is common, but not always present. Gastrointestinal symptoms, including diarrhoea, have also been reported. ◦Some laboratory-confirmed cases of MERS-CoV infection are reported as asymptomatic. COVID-19: ◦Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). ◦The virus first invades the upper respirator tract, leading to: ‣ A high temperature ‣ A new, continuous cough ‣ A loss or change to your sense of smell or taste