Infective diseases Part 1 Flashcards

Question

What are Major Infectious Diseases of the URT?

Answer 1

Pharyngitis Laryngitis Rhinitis Tonsilitis Sinusitis

Answer 2

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

Answer 3

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

Answer 4

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.

Answer 5

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

Answer 6

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.

Answer 7

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

Answer 8

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.

Answer 9

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 called seasonal 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)

Answer 10

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 called swine flu) was identified in the United States and Mexico and 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

Answer 11

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

Answer 12

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.

Answer 13

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)

Answer 14

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

Answer 15

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.

Answer 16

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

Answer 17

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.

Answer 18

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

Answer 19

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

Answer 20

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.

Answer 21

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

Answer 22

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

Answer 23

Norovirus, rotavirus, adenovirus, and others

Answer 24

Salmonella, campylobacter, shigella, E coli

Answer 25

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

Answer 26

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

Answer 27

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

Answer 28

Tend to be multi-resistant unusual infections which are rare in the community examples: Clostridium difficile MRSA – Methacillin resistant staphloccus aureus

Answer 29

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

Answer 30

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

Answer 31

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.

Answer 32

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

Answer 33

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

Infective diseases Part 1 Flashcards

(57 cards)