LECTURE 1.1 INTRODUCTION TO INFECTION BLOCK

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Questions and Answers

What is the purpose of taking a detailed history in a patient with an infection?

To determine the severity of the infection

To gather information about the patient's symptoms, environment, and contacts (correct)

To rule out other possible diagnoses

To identify the causative microorganism

What is the primary function of interleukin 1 in the body's response to infection?

To trigger the release of white blood cells

To stimulate the production of C-reactive protein

To increase the body's temperature (correct)

To activate the immune system's response to infection

Which of the following microorganisms is typically transmitted through insects?

Malaria (correct)

E. coli

Hepatitis A

SARS-CoV-2

What is a common symptom of a chest infection such as pneumonia?

Breathlessness Signup and view all the answers

What is the purpose of a Gram stain in the diagnosis of bacterial infections?

To differentiate between gram-positive and gram-negative bacteria Signup and view all the answers

Which of the following is a marker of infection and inflammation?

C-reactive protein Signup and view all the answers

What is the primary function of interleukin 6 in the body's response to infection?

To trigger the release of C-reactive protein Signup and view all the answers

What is the primary mode of transmission for the disease cholera?

Contaminated water Signup and view all the answers

What type of immunisation is achieved through immunoglobulins from human serum?

Passive immunisation Signup and view all the answers

Which of the following is a symptom of a skin infection such as cellulitis?

Redness, heat, and pain at the site of infection Signup and view all the answers

What is the primary function of a white blood cell count in the diagnosis of infection?

To detect the presence of an infection Signup and view all the answers

What is the primary cause of SARS?

SARS-CoV Signup and view all the answers

Which of the following vaccines is an example of a non-replicating viral vector?

Oxford/AstraZeneca vaccine Signup and view all the answers

What is the primary mode of transmission of SARS?

Respiratory droplets from coughs and sneezes Signup and view all the answers

What is the main difference between passive immunisation and active immunisation?

Duration of immunity Signup and view all the answers

Which of the following vaccines is an example of an inactivated virus particle?

Novavax COVID-19 vaccine Signup and view all the answers

What is the primary cause of MERS?

MERS-CoV Signup and view all the answers

What is the purpose of Koch's postulates?

To establish a causal link between a microorganism and a disease Signup and view all the answers

What is the main advantage of passive immunisation?

Provides immediate immunity Signup and view all the answers

How many vaccines were in early pre-clinical development against SARS-CoV-2?

More than 100 Signup and view all the answers

What is the primary purpose of a blood culture in investigating infections?

To identify microorganisms in the bloodstream Signup and view all the answers

Which of the following investigations is commonly used in chest infections and TB?

X-ray Signup and view all the answers

What is the primary purpose of quarantine in infection control?

To reduce the transmission of infection in the community Signup and view all the answers

Which of the following tests is commonly used to diagnose hepatitis?

Antigen test Signup and view all the answers

What is the primary purpose of hand hygiene in infection control?

To reduce the transmission of infection Signup and view all the answers

Which of the following investigations is commonly used to diagnose viral infections?

Nucleic acid amplification/PCR Signup and view all the answers

What is the primary purpose of ethical dilemmas in infection control?

To make difficult decisions about patient confidentiality Signup and view all the answers

Which of the following is a general public health measure in infection control?

Hand hygiene Signup and view all the answers

What is the primary purpose of CT scans in investigating infections?

To identify the source of infection in the body Signup and view all the answers

Which of the following is a limitation of quarantine in infection control?

Has a significant impact on mental health Signup and view all the answers

Study Notes

Microorganisms Causing Disease

Bacteria, viruses, fungi, protozoa, helminths (worms), and prions can cause disease

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:
- 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 many 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 fasciitis: 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 increases in infection, but may decrease in some cases (e.g., CD4+ cells in HIV)
- Interleukin 6 is a cytokine involved in this process
C-reactive protein: increases in infection and inflammation

Tests for Cause of Infection

Bacteria:
- Direct microscopy after staining (Gram stain, acid-fast stain)
- Blood culture (growth and identification)
- Swabs (direct staining and microscopy, growth in appropriate medium)
- Nucleic acid amplification/PCR
- Antigen tests (e.g., hepatitis)
- Antibody tests
Viruses:
- Detection of antigens using Elisa/immunofluorescence
- Nucleic acid amplifications/PCR
- Antibody tests

Investigations for Infection

X-ray (used 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)

Vaccines

Passive immunization:
- 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
SARS-CoV-2 vaccines:
- Examples: Pfizer, Moderna, Oxford/AstraZeneca, and Johnson and Johnson/Janssen vaccines
- 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/BioNTech bivalent COVID-19 vaccine
- Moderna COVID-19 vaccine
- Moderna bivalent COVID-19 vaccine
- Novavax COVID-19 vaccine (Nuvaxovid)

SARS and MERS

SARS:
- Caused by SARS-CoV (bats to other animals and people)
- Symptoms: respiratory problems, dry cough, fever, head and body aches
- Spread through respiratory droplets from coughs and sneezes
MERS:
- Caused by MERS-CoV (direct or indirect contact with infected dromedary camels)
- Symptoms: fever, cough, and shortness of breath
- Pneumonia is common, but not always present
- Gastrointestinal symptoms, including diarrhea, have also been reported
- Some laboratory-confirmed cases of MERS-CoV infection are reported as asymptomatic

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Description

This quiz covers the different types of microorganisms that can cause disease, modes of transmission, and the importance of taking detailed history in infection diagnosis.