Health & Safety Flashcards
1
Q
What are the transmission routes of micro-organisms?
A
- Soil
- Animals/Insects
- Food/Water
- Faecal-Oral
- Aerosol
- Direct Contact
- Transplacental
- Iatrogenic
2
Q
What are some examples of transmission of micro-organisms through soil?
A
Worms/some bacteria - eg Ascaris lumbricoides; Cl. tetani
3
Q
What are some examples of transmission of micro-organisms through animals/insects?
A
e.g. rabies virus; Plasmodium spp. (malaria)
4
Q
What are some examples of transmission of micro-organisms through food/water?
A
e.g. Enterobacteria; hepatitis A virus; vCJD
5
Q
What are some examples of transmission of micro-organisms through faecal-oral?
A
e.g. Enterobacteria; hepatitis A; noroviruses
6
Q
What are some examples of transmission of micro-organisms through aerosol?
A
e.g. B. pertussis (whooping cough); measles & influenza viruses
7
Q
What are some examples of transmission of micro-organisms through direct contact?
A
e.g. sexual; e.g. HIV infection; some herpesviruses
8
Q
What are some examples of transmission of micro-organisms through transplacental?
A
e.g. rubella virus; Zika virus
9
Q
What are some examples of transmission of micro-organisms through iatrogenic?
A
e.g. blood; hepatitis B and C; HIV
10
Q
What is Ascaris Lumbricoides?
A
Transmission of intestinal roundworm (nematode) through soil
11
Q
What is Tetanus caused by?
A
Clostridium Tentani which is transmitted through soil
12
Q
What is rabies caused by?
A
Infection through animals. Vaccine-preventable viral disease occurring in more than 150 countries/territories
13
Q
What is the main source of human rabies deaths?
A
Dogs contribute up to 99% of all rabies transmissions to humans
14
Q
What % of people are children when bitten by a rabid animal?
A
40%
15
Q
What is an immediate reaction you need to do in a suspected rabies case?
A
Immediate, thorough wound washing with soap and water after contact with a suspect rabid animal is crucial and can save lives
16
Q
What is Toxoplasma Gondii?
A
A unicellular parasite caused by domestic animals
17
Q
How does a human get toxoplasma gondii?
A
- Cat ingests cysts of Toxoplasma gondii in raw meat of mice (intestine)
- Bradyzoites released from the cyst, parasite gains entry into the mucosa
- Bradyzoites differentiate into gametocytes
- After fusion, oocysts are excreted in cat faeces
- Intermediate host
- Human infection occurs by consumption of meat of an infected animal or ingestion of the oocyst
18
Q
What is Malaria caused by?
A
The female Anopheles mosquito and the malaria protozoan - Plasmodium falciparum
19
Q
What is the mosquito transmission cycle?
A
- Bite from infected mosquito transmits malaria
- Parasites travel to liver where they lie dormant, usually about 10 days to 4 weeks
- Parasites leave the liver and infect red blood cells. This is when malaria signs and symptoms typically develop
- Malaria is transmitted to an uninfected mosquito when it bites someone with the disease. That mosquito can then spread malaria to other humans.
20
Q
What can Malaria cause?
A
- Cerebral malaria (brain swelling)
- Breathing problems (pulmonary edema)
- Organ failure of kidneys, liver or spleen
- Anemia
- Hypoglycemia (low blood sugar)
21
Q
How are micro-organisms transmitted in a healthcare setting?
A
- Through cross-infection (patient to patient), either directly or indirectly
- From patient to healthcare worker
- From healthcare worker to patient
22
Q
What is percutaneous transmission?
A
Injuries through needles and other sharps, human bites and human scratches
23
Q
What is mucocutaneous transmission?
A
Exposures to the mucous membranes of the eyes and mouth.
24
Q
What are some contaminated sources that may result in transmission of micro-organisms between humans?
A
- Mucosal secretions and saliva
- Fluids from vesicles or other open lesions
- Faeces, vomit and urine
- Fomites
- Pus
- Blood
25
What are Fomites?
Fomites are objects or things e.g. a cup or the surface of a table or a bedsheet.
26
What are Nosocomial Infections?
Nosocomial infections are infections occurring in hospitals
27
How are respiratory tract infections spread?
Spread via mucosal secretions (coughs/sneezes)
28
Is measles or ebola more infective aerobically?
Measles very infective, you score in infectiousness. Find Measles to be 14 on this which means 1 in 14 infected. Relatively small virus so can go quite far whereas Ebola has a lower transmission in aerosols because it’s larger in size.
29
How do we prevent micro-organism transmission and spread in the healthcare setting?
1. Handwashing and good general hygienic procedures
2. Use of appropriate protective clothing
3. Appropriate and effective sterilisation of instruments
4. Education and awareness
5. Immunisation, where available
30
What are some examples of bacteria?
- Staphylococcus aureus/MRSA
- Pseudomonas aeruginosa
- Streptococcus pyogenes
- Clostridioides difficile
- Klebsiella sp.
- Bordetella pertussis
31
What are some examples of viruses?
- HIV (blood-borne)
- Hepatitis B and C (blood-borne)
- Herpes simplex virus (HSV) type 1 (from infected lesion fluids)
- Noroviruses (from infected faeces or vomit)
- Adenoviruses (from infected body fluids)
- Ebola viruses (from all infected body fluids)
- Coronavirus (respiratory)
32
What is MRSA also known as?
Staphylococcus aureus
33
How many people carry staphylococcus aureus asymptomatically?
About 30% of people carriers without symptoms
34
Why is MRSA/Staphylococcus Aureus serious in healthcare settings?
In healthcare settings, S. aureus infections can be serious or fatal (bacteraemia or sepsis (starts flu-like but is life or death), pneumonia, endocarditis, bone infections)
35
What is c.diff actually called?
Clostridioides Difficile
36
What does Clostridioides difficile/ c. diff cause?
Symptoms:
- Severe diarrhoea including loose, water stools
- Colitis
- Frequent bowel movements for several days
- Fever/stomach tenderness
- Pain/nausea
37
What is Klebsiella sp?
- Genus of Gram-negative, oxidase-negative, rod-shaped bacteria
- Normally found in the human intestines (not causing disease)/faeces
38
What are the symptoms of klebsiella sp?
Causes:
- Pneumonia,
- Bloodstream infections, wound or surgical site infections,
- Meningitis
39
Who is at risk of Klebisella sp?
Patients at risk – on ventilators or catheters/on long course of antibiotics
40
What is Pseudomonas Aeruginosa?
Serious infections usually to people in the hospital and/or with weakened immune systems
41
What can Pseudomonas Aerguinosa cause?
P. aeruginosa can cause infections in the blood, lungs (pneumonia), urinary tract or other parts of the body after surgery.
Can lead to severe illness and death in these people
42
What are some mild illnesses caused by pseudomonas aeruginosa?
Healthy individuals can also develop mild illnesses - ear infections, especially in children and skin rashes after exposure to contaminated swimming pools
Eye infections have occasionally been reported in persons using extended-wear contact lenses
43
How are pseudomonas aeruginosa spread?
Can be spread on the hands of healthcare workers or by equipment that gets contaminated and is not properly cleaned
44
What is Group A Strep also known as?
Streptococcus pyogenes (Group A Strep)
45
What does Streptococcus pyogenes (Group A Strep) cause?
Acute infections may take the form of pharyngitis, scarlet fever (rash), impetigo, cellulitis, or erysipelas
Invasive infections can result in necrotizing fasciitis, myositis and streptococcal toxic shock syndrome
46
How does Streptococcus pyogenes (Group A Strep) spread?
Highly contagious/spreads through airborne droplets when someone with the infection coughs or sneezes, or through shared food or drinks
47
What is Whooping cough also known as?
Bordetella Pertussis
48
How is Whooping cough spread?
Saliva
Pertussis is a highly contagious disease of the respiratory tract
49
Who does Whooping cough (Bordetella pertussis) affect the most?
The disease is most dangerous in infants and spreads easily from person to person, mainly through droplets produced by coughing or sneezing.
50
What are the symptoms of Whooping cough (Bordetella pertussis)?
- The first symptoms generally appear 7–10 days after infection, and include mild fever, runny nose, and cough, which in typical cases gradually develops into a paroxysmal cough followed by whooping
- Coughing spells can last 4 - 8 weeks in children
- In the youngest infants, the paroxysms may be followed by periods of apnoea.
51
What is a common complication of Whooping cough (Bordetella pertussis)?
Pneumonia is a relatively common complication; seizures and encephalopathy occur more rarely.
52
How long are Whooping cough (Bordetella pertussis) patients contagious?
Untreated patients may be contagious for three weeks or more following onset of the cough. Pertussis can be prevented by immunization.
53
How is HIV-1 spread?
Spread from contaminated needles, blood or blood-products, the main problem for hospitals
54
How is HIV-1 spread?
Virus has been isolated from human blood, semen, vaginal secretions, saliva, tears and breast milk. Commonest routes of transmission are via blood, semen and vaginal secretions
Contact with saliva is not a route of infection, and there is no evidence for transmission by an airborne route or via food, water, fomites or insects
55
What must be present for HIV-1 to infect?
Skin or mucous membranes must be broken for HIV-1 to infect
56
What are risks of transmission of HIV-1 and what % of all infections do they make up?
- Blood transfusions & Factor VIII
3 - 5% of all infections
Rate of transmission from infected blood by transfusion – 90%
- Intravenous Drug Abuse
5 - 10% of all infections
Rate of transmission from needle stick – 0.5% per episode
- Sexual Intercourse
80% of all infections
Rate of transmission following vaginal intercourse – 0.1% per episode
Rate of transmission following anal intercourse – 1.0% per episode
Concurrent STD enhances above risks by 10x
- Perinatal Infection
10% of all infections
Rate of transmission from mother to infant – 12% - 40%
57
What are the stages of HIV-1 replication?
1. Attachment to host cell receptor
2. Viral core with ssRNA and reverse transcriptase (RT) enzyme released into the host cell cytoplasm
3. RT enzyme converts viral ssRNA into viral dsDNA
4. Viral dsDNA enters host cell nucleus and is incorporated into the host cell genome through activity of viral integrase enzyme
5. Integrated viral dsDNA (termed ‘provirus’) remains latent in host cell genome until cell is activated by a foreign protein
6. Following activation of the cell, dsDNA of provirus is transcribed into viral ssRNA. This migrates into host cell cytoplasm
7. Viral ssRNA replicates itself to form progeny ssRNA and also acts as a viral messenger RNA for manufacture of progeny viral proteins
8. Progeny viral ssRNA and viral core proteins assemble to form progeny viral cores. Progeny viral envelope protein is inserted into host cell membrane
9. Newly formed viral particles released to exterior of cell by budding
58
What is HIV?
HIV is a chronic infection with ongoing viral replication
Causes progressive decline in CD4+ T-lymphocyte count. Below 200 cells/ml, the individual is defined as having Acquired Immunodeficiency Syndrome (AIDS), and is at risk of opportunistic infections
On average it takes 10 years to progress to AIDS in an untreated person but there is wide individual variation
The major determinant of the rate of progression to AIDS is the amount of HIV virus particles in the bloodstream
59
What is the pathogenesis (process of leading to disease) of HIV infection?
1. Acute infection with spread to lymphoid tissue
2. Virus present in CD4+ helper T lymphocytes and macrophages in both a latent (hidden) and a replicative form
3. Control of the infection by the immune defences, particularly via cytotoxic T lymphocytes (CD8+ cells)
4. Loss of immune control with time, virus escape by genetic variability
5. Loss of greater numbers of helper T lymphocytes through virus and host cell destruction
6. Development of AIDS and the appearance of opportunist infections
60
What are some opportunistic infections in AIDS patients?
Bacterial skin infections
- Seborrhoeic dermatitis
- Folliculitis (both caused by Staphylococcus aureus)
Fungal skin infections
- Candidiasis
Viral skin infections
- Zoster/Shingles
- Herpes simplex virus
- Warts
61
What is the procedure following accidental exposure to HIV-1?
1. The nature and extent of the exposure is assessed immediately by an informed clinician
2. Treatment with appropriate anti-HIV drugs should be commenced immediately
3. Usually a combination of drugs is used, including reverse transcriptase inhibitors and protease inhibitors
62
What is the classification of Hep B, Hep C and Hep A?
Hep B - Hepadnavirus
Hep C - Flavivirus
Hep A - Enterovirus
63
What are some features of Hep B?
Hepatitis B (HBV) has a long incubation period, some antigenic variation, carrier state, DNA
64
What are some features of Hep C (HCV)?
Long incubation period, much antigenic variation, carrier state, RNA
65
What are some features of Hep A (HAV)?
Short incubation period, little antigenic variation, no carrier state, RNA
66
What are some symptoms of Hepatitis?
- Anorexia
- Malaise
- Nausea
- Aches in back and limbs
67
What are some clinical signs of Hepatitis?
- Jaundice
- Enlarged liver (hepatomegaly)
- Enlarged spleen (splenomegaly)
- Slightly raised temperature
- Pale stools
- Blood in urine (haematuria)
68
Who are most at risk in the UK of Hep B & C?
- Drug addicts (declining due to available vaccine for Hep B)
- Individuals with lympho-proliferative disorders
- Individuals on immune suppressive therapy
- Users of blood or blood products on a regular basis
- Individuals in ‘at risk’ occupations
69
In an unvaccinated person infected with Hep B what happens?
25% = acute hep leading to 1% dying
75% transient subclinical disease with 100% fully recovering
10% develop chronic liver disease with 10 - 30% of these people getting cirrhosis of the liver leading to primary hepatocellular carcinoma.
70
How many genotypes and subtypes are there of Hep C (HCV)?
There are 6 HCV genotypes and about 80 subtypes within the six genotypes
HCV persists in 70 - 80% of infections
71
How is HCV diagnosed?
Diagnosis and screening is by an ELISA test for viral antibody, but HCV infection is difficult to recognise in its early stages
72
How is Hep B (HBV) controlled?
HEPATITIS B
- Screening of blood and blood products
- Hygienic measures (contaminated needles, tattoos, sexual contact)
- Vaccination against HBV – the subunit HBsAg preparation
73
How is Hep C (HVC) controlled?
- Screening of blood and blood products
- Hygienic measures (contaminated needles, tattoos, sexual contact)
- No vaccine against HCV yet available!
74
How is Hep A (HAV) controlled?
HEPATITIS A
- Hygienic measures (faecal-oral spread)
- Common vehicle outbreaks (contaminated water/food)
- Inactivated, whole virus vaccine
75
What can ulcerating herpes simplex virus (HESV1) cause?
Lesions around mouth (cold sores) and on finger
76
How is ulcerating herpes simplex virus (HESV1) spread?
Spread through fluids from ulcers
(open lesions)
(HSV2 sexual contact)
77
How are Norovirus infections spread?
Spread from faeces and vomit
78
What is Adenoviral Conjunctivitis?
A highly contagious form of "pink eye," is caused by adenoviruses and presents with symptoms like red, watery, and painful eyes, potentially accompanied by flu-like symptoms and swollen lymph nodes.
Spread from eye and oral secretions
79
What is Adenoviral Conjunctivitis transmitted? What is it associated with?
- Transmission through contact with infected upper respiratory droplets, fomites, contaminated swimming pool
- Often associated with an infection of the upper respiratory tract, common cold or sore throat
- Watery discharge, variable itch
80
What is Ebola virus?
Ebola is a severe haemorrhagic disease caused by negative sense ssRNA viruses of the genus Ebolavirus in the family Filoviridae
Filovirus particles form twisted filaments of 80nm diameter, with a genome that codes for 8 proteins
81
What is Ebola caused by?
Infection of humans is probably via fruit bats. In some ‘at risk’ countries the sale of fruit bats for culinary purposes is now banned
82
How is Ebola spread?
All bodily fluids are infectious; full body protective clothing must be worn by medical and ancillary staff dealing with patients and samples
83
What are some symptoms of Ebola?
Early symptoms include fever, diarrhoea, vomiting; later, there is renal failure, shock and terminal haemorrhagic fever.
The case fatality rate in the recent outbreak was 61%
