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Clinical Diagnosis > Infective diseases Part 1 > Flashcards

Infective diseases Part 1 Flashcards

1
Q

The most frequent respiratory tract infections are due to viruses and bacteria causing conditions such as?

A

bronchiolitis, lobar pneumonia, tuberculosis

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2
Q

Chronic Exposure to pollutants & toxic substances can lead to common chronic lung conditions such as?

A

asthma, chronic bronchitis, emphysema, pulmonary fibrosis

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3
Q

Tumours of the bronchial tree & lung are common. Tracheal tumours are often secondary cancers.
True or false?

A

True

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4
Q

The lung is also important because it is frequently the secondary victim of failure elsewhere.
Left sided heart failure leads to a back up of pressure causing pulmonary edema. True or false?

A

True

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5
Q

Lung Abnormalities in premature infants can predispose illness and unfortunately can be a common cause of death. True or false

A

True

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6
Q

With regards to respiration, what do the nostrils do?

A

Way for air to enter the body

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7
Q

With regards to respiration, what does the pharynx do?

A

Channels the air down the airways

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8
Q

With regards to respiration, what is the pleural membrane?

A

Helps keep the lungs flexible

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9
Q

With regards to respiration, what does the right primary bronchus do?

A

Allows air to enter the right lung

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10
Q

With regards to respiration, what do the ribs do?

A

Protects the respiratory organs

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11
Q

With regards to respiration, what do the intercostal muscles do?

A

Moves the ribs during breathing

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12
Q

With regards to respiration, what does the diaphragm do?

A

Helps pump the lungs

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13
Q

With regards to respiration, what does the nasal cavity do?

A

Purifies, humidifies the air

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14
Q

With regards to respiration, what does the oral cavity do?

A

Lets air and food enter

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15
Q

With regards to respiration, what does the epiglottis do?

A

Keeps food from entering the airways

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16
Q

With regards to respiration, what does the larynx do?

A

Letting air pass through speech production

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17
Q

With regards to respiration, what does the trachea do?

A

Channels the air toward the left/right bronchi

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18
Q

With regards to respiration, what does the left primary bronchus do?

A

Allows air to enter the left lung

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19
Q

With regards to respiration, what do the bronchioles do?

A

Lets air reach the alveoli

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20
Q

With regards to respiration, what does the alveoli do?

A

Site for O2-CO2 exchange

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21
Q

With regards to respiration, what do the lungs do?

A

Carries out O2 - CO2 gas exchange

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22
Q

What is the Upper Respiratory Tract? (URT)

A

URT plays a crucial role in defending against and filtering out foreign material such as bacterial cells, viruses and dust particles carrying microbes.
Mucus from goblet cells and mucosal glands trap microbes & particulate matter.
URT has ciliated epithelium involved in a defensive process that propel the mucus towards the pharynx for expectoration.
There are also antimicrobial substances present including interferon (activates immune cells) and human defensins (disrupt bacterial cell membrane)

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23
Q

Why do smokers get more respiratory infections than non smokers?

A

Ciliary function is impaired
Mucus volume is increased by epithelial cells
Alterations in immunity – humoral response to antigens altered/quantitative and qualitative changes in cellular components occur
Some of these changes revert to normal on cessation of smoking
If continued long term, irreversible damage occurs

This is why smoking is a RISK FACTOR for increased chance of respiratory tract infections (and other diseases!)

24
Q

What is the lower respiratory tract?

A

Alveoli and respiratory bronchioles are not ciliated but the alveolar fluid contains antimicrobial components including immunoglobulins.

It was previously thought that the LRT was sterile but it appears that this area does contain a variety of resident microbes.

25
Q

What are Major Infectious Diseases of the URT?

A

Pharyngitis
Laryngitis
Rhinitis
Tonsilitis
Sinusitis

26
Q

What is pharyngitis?

A

Common infectious disease
Inflammation of the pharynx and sometimes tonsils (tonsillitis) usually due to a viral infection i.e the common cold
However, Streptococcus pyogenes is a gram positive coccus which causes a more serious pharyngitis
or ‘Strep throat’
It is spread through respiratory droplets and the inflammation is due to bacterial toxins.

A serious complication of this bacterial infection is Rheumatic Fever.

Antibodies to S. pyogenes mistakenly cross react with similar proteins on heart muscle. This can lead to permanent scarring and distortion of the heart valves causing rheumatic heart disease.

Symptoms include:
swollen tender joints – especially knees & ankles, muscle weakness, shortness of breath, fever, rash, chest discomfort

27
Q

What is sinusitis?

A

Can be infective or non infective (allergy)
Often occurs in connection with rhinitis
Acute sinusitis can be caused by a variety of indigenous microbes in the URT but most infections are viral

If untreated most infections resolve spontaneously but severe bacterial infections can lead to chronic sinusitis that can last up to 12 weeks

28
Q

What is Acute Otitis Media?

A

Although your ears aren’t part of your respiratory tract…

Streptococcus pneumonia or Haemophilus Influenza can cause otitis media in children.

Strep. P will first colonize the mucosal surface of the nasopharynx, and then can spread to infect the middle ear via the Eustachian tubes to cause acute Otitis Media.

29
Q

What is the common cold?

A

Caused by rhinoviruses – over 100 small, naked, single-stranded RNA viruses
Also caused by adenoviruses and coronaviruses.
About 90% of human rhinoviruses cause immune cells to produce anti-inflammatory cytokines which slows down the onset of the symptoms

30
Q

How common is the common cold?

A

The incidence of the common cold declines with age.
Children under two years have about six infections a year
adults two to three
older people about one per year.

31
Q

How is the common cold spread?

A

The virus is spread by hand contact with secretions from an infected person (direct or indirect) or aerosol of the secretions and virus.

32
Q

What is Bordetella Pertussis (whooping cough)?

A

The exotoxin that the bacteria produce, paralyses the ciliated cells and impairs mucus movement potentially causing pneumonia.
Particularly severe in babies.
Rarely seen now, due to the success of the immunisation programme/general health measures.

33
Q

What is Influenza?

A

Highly infectious acute respiratory disease
Transmitted through airborne respiratory droplets
There are: Influenza A,B and C viruses
These viruses contain the glycoprotein Haemaggluinin and Neuraminidase, hence H1N1
Each year a slightly different flu subtype evolves based, in part, to changes in the H and/or N spike proteins
Most deaths are due to secondary bacterial pneumonia
It appears a flu infection can trigger S.pneumoniae to disperse from the biofilm in the nose or throat and colonize the lung leading to bacterial pneumonia
As influenza circulates each year in the UK during the winter months (generally October to April), it is sometimes calledseasonal flu
There are slight changes to the virus from the previous year which means that some people who encounter the new virus may no longer be fully immune.
This is why a vaccine is developed for each season which is offered free to some children, everyone aged 65 and over, people in certain ‘at-risk’ groups who are more likely to develop complications as a result of having flu
(and also those who look after people at increased risk- e.g. health workers, social workers etc)

34
Q

What is the difference between influenza and other flu?

A

Seasonal flu is not the same as pandemic flu.
Pandemics arise when a new influenza virus emerges which is capable of spreading in the worldwide population.
A pandemic occurred in 2009/10 when a new strain of pandemic influenza A(H1N1) (commonly calledswine flu) was identified in theUnited StatesandMexicoand subsequently spread worldwide.
COVID-19 Pandemic 2019/20 which we are all very aware of!

Avian flu (Bird flu) in birds has now jumped the species barrier and is causing rare sporadic human cases in asia

35
Q

Name Lower Respiratory Tract Infections?

A

Bronchitis
(or acute exacerbation of chronic bronchitis)
Pneumonia
Bronchiolitis
Tuberculosis

36
Q

What is Tuberculosis?

A

Caused by Mycobacterium Tuberculosis
Small aerobic, non-motile rod – cell wall forms a waxy cell surface providing resistance to drying, chemicals and many antibiotics.
Causes tubercles
mass of lymphocytes, macrophages and giant cells.
Airborne disease spread by droplets.
Long incubation time 2-12 weeks
Latent phase where the infection is arrested
Can get reactivation into secondary TB disease.

37
Q

What is Pneumonia?

A

Can be acute (24 – 48hr period) or chronic (over several weeks)

Caused by a variety of bacterial species
Divided into Healthcare acquired (HCAP) or Community acquired (CAP)

38
Q

What is HCAP - healthcare acquired pneumonia?

A

Associated with mechanical ventilation i.e tracheal intubation to assist breathing or patients with multiple co-morbidities or immunosuppressed

Commonly caused by:
Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas pneumoniae, & Acinetobacter pneumoniae

39
Q

What is CAP (Community Acquired Pneumonia)?

A

Most Common Type
caused by Steptococcus pnemoniae.
Exists in all age groups but mortality rate highest in the elderly.
Acquired through aspiration of droplets
Predisposing factors include:
malnutrition, smoking, viral infections, and treatment with immunosuppressant drugs.
Over 90 serotypes known so it is possible to become infected with different subtypes at different times.
Polyvalent vaccine works against 23 serotypes which accounts for about 90% of all pneumonia cases.

40
Q

What is viral pneumonia?

A

Primary viral pneumonia is uncommon in adults
Influenza A infection being the commonest cause.

It predisposes patients to bacterial pneumonia by damaging the respiratory epithelium and facilitating bacterial infection.

Patients present with fever, breathlessness, cough & diarrhoea

41
Q

What is Lobar Pneumonia (aka Bronchopneumonia)?

A

In bronchopneumonia, the primary infection is centred on the bronchi and then spreads to involve adjacent alveoli.
These alveoli become filled with inflammatory exudate and the affected lungs become consolidated
Initially the consolidation is patchy withing the lungs, but if untreated becomes confluent (involving lobes).
Most commonly the lower lobes which are affected
Involvement of the pleura is common and leads to pleurisy.
Patients with lobar pneumonia are often severely ill.
If not treated quickly, can lead to permanent lung scarring which causing permanent lung dysfunction
Common complication include:
Pleurisy, lung abscess and septicemia.

42
Q

What is Aspergillosis?

A

Primarily caused by the fungus Aspergillus fumigatus
Present in soil, decaying vegetation and mould which produces spores that are inhaled.
In the alveoli a tangled ball of fungal mycellium forms.
Invasive aspergillosis – fatal form whereby the fungal infection spreads to skin, heart, kidneys or brain.
Can also lead to development of pneumonia

43
Q

What are our Digestive System’s Defence System of the mouth?

A

Dental caries (tooth decay)
Bacterial cells normally adhere to and colonise the tooth surface. With poor dental hygiene bacterial cells convert carbohydrates to acids
Streptococcus mutans & Streptococcus sobrinus are the main acid producers.
Once colonization starts a succession of bacterial species interact and form dental plaque

44
Q

What is Periodontal disease?

A

Swollen and tender gums that bleed when brushing is a sign of periodontal disease
This gingivitis is caused by Porphyromonas gingivalis
If untreated this causes periodontitis – a serious chronic inflammatory disease of soft tissue and bone support causing tooth loss.

45
Q

What is Gastroenteritis?

A

Aetiology depends on:
Incubation period
How long after ingestion before symptoms appear
Can range from hours to days
Clinical symptoms
Nausea, abdominal cramps, vomiting & diarrhoea
Duration of illness
Varies greatly
Demographics
Infants, elderly, immunocompromised, environmental

46
Q

What type of infections cause Gastroenteritis?

A

Bacterial, viral, fungal, and parasitic
mc = viral, bacterial, parasitic then fungal

47
Q

What are the most common viral types of Gastroenteritis?

A

Norovirus, rotavirus, adenovirus, and others

48
Q

in gastroenteritis, Only 5% of stool cultures grow bacteria, & the most common bacterial types?

A

Salmonella, campylobacter, shigella, E coli

49
Q

What is viral Gastroenteritis?

A

Causes diarrhoea, vomiting, nausea, low grade fever, cramping, headache & malaise
An example is Norovirus

50
Q

What is Norovirus?

A

Viral aka “winter vomiting bug”
Highly contagious with as few as 18 virus particles needed to cause an illness in a healthy individual
Incubation period 15-48hrs
Symptoms: Fever, diarrhoea, abdominal pain & extensive vomiting
Lasts 24-48hrs

51
Q

What is bacterial Gastroenteritis?

A

5 Common types:
Escherichia coli
Salmonella
Shigella
Campylobacter

Symptoms: vomiting, abdominal cramps, nausea, low grade fever
Spread by faeco-oral route
Lasts 3-7 days

52
Q

What are examples of hospital infections?

A

Tend to be multi-resistant unusual infections which are rare in the community

examples:
Clostridium difficile
MRSA – Methacillin resistant staphloccus aureus

53
Q

What is Clostridium difficile?

A

C.diff – anaerobic, spore-forming gram positive rod.

Associated with food borne or intestinal infections
present in faeces so toilet surfaces etc that become infected may serve as a reservoir for C.diff spores

In certain healthcare settings – associated infections have reached epidemic proportions
Most at risk are elderly people and those who have been taking certain broad-spectrum antibiotics for a prolonged time.

The pathogen produces 2 toxins
Enterotoxin causing fluid loss & diarrhoea
Cytotoxin causing further mucosal injury leading to pseudomembraneous colitis

54
Q

What are Gastric Ulcers?

A

Helicobacter pylori – microaerophilic gram negative curved rod

Attaches to stomach wall & penetrates the stomach mucosa.
Secretes urease (urea >ammonia)
Ammonia & H.pylori cytotoxin cause destruction of the mucus-secreting cells exposing the underlying connective tissue to stomach acid
Symptoms
severe pain
heartburn
indigestion
nausea

55
Q

What is Hepatitis A?

A

Caused by Hep A virus
Faecal – oral route from shellfish like clams & oysters contaminated with sewage
Incubation period 4 weeks
Initial symptoms:
anorexia, nausea, vomiting & low grade fever.
Virus then transported to liver to produce upper right quadrant discomfort and jaundice
HAV does not cause chronic hepatitis
Convalescence 2-3 months
Can be avoided by immunisation
Nb. Hepatitis B transmitted by exposure to infectious blood or bodily fluids. Hepatitis C transmitted blood to blood i.e via transfusions, intravenous drug use, etc.

56
Q

Tell me about fungi, parasites etc?

A

Fungi – no major infectious diseases of the digestive system caused by fungi,
however some mushrooms are poisonous i.e Amanita phalloides. Also Candida can become a problem.
Parasites e.g. giardia
Helminths living inside the digestive tract are the intestinal worms:
Flatworms i.e. tapeworms
Roundworm
Pin/thread worm
Hookworm

57
Q

What is Giardiasis?

A

Caused by parasite - G.intestinalis or G.lamblia
Incubation period 7 days
Transmitted by food or water containing dormant Giardia cysts that colonize and reproduce in the small intestine
Symptoms
nausea, gastric cramps, flatulence & watery diarrhoea lasting 1-3 weeks

Clinical Diagnosis (22 decks)

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