Respiratory Tract infections

Question 1

Community acquired pneumonia

Answer 1

Occurs in community, outside the hospital setting

Question 2

Most common bacterial cause of pneumonia

Answer 2

Steptococcus pneumoniae

Question 3

2nd most common cause of bacterial pneumonia

Answer 3

Heamophilis influenza type B

Question 4

Viral cause of pneumonia

Answer 4

Respiratory syncytial virus

Question 5

in children infected with HIV, which virus is responsible for deaths in infants

Answer 5

pneumonocystis jiroveci

Question 6

Hospital acquired pneumonia

Answer 6

Occurs in hospital settings- more serious

Question 7

Ventilator associated pneumonia

Answer 7

Occurs in people using ventilators

Question 8

Name some bacterial species which cause HAP and VAP?

Answer 8

Staphylococcus aureus, pseudomonas aeruginosa, E.coli, Enterobacter

Question 9

Symptoms of mild pneumonia

Answer 9

cough, excess mucus and sputum, shortness of breath and chest pain

Question 10

Symtpoms of severe pneumonia

Answer 10

all symptoms of mild pneumonia + fever, nausea, confusion and many complications

Question 11

LRTIs can affect bronchial trees leading to

Answer 11

bronchtitis

Question 12

LRTIs can affect lung parachyma as

Answer 12

pneumonia

Question 13

Bronchopneumoniae

Answer 13

When infection from bronchitis spreads to surrounding lung parenchyma

Question 14

Bronchiectasis

Answer 14

irreversible dilation of bronchi due to broncial wall damage and inflammation

Question 15

How is pneumonia spread

Answer 15

1- Inhalation of airborne droplets
Involves breathing in infectious droplets released by coughing, sneezing or talking
2- Apsiration of upper respiratory tract flora (aspiration refers to inhalation of material into lungs that shouldn’t go there).
This involves aspiration of commensal organisms like staphylococci, streptococci and haemophilis influenzae which are usually taken in during sleep.
High risk groups include ppts on long term-anaesthesia, respirators and alcohol abusers.
3- infection reaches the lungs via the bloodstream. E.g. neonatal sepsis
4- Exogenous penetration/ contamination-
this is when an infection enters lung tissue from an outside environment. these could be from trauma, surgery or contaminated medical equipment

Question 16

In healthy individuals LRT is kept sterile how?

Answer 16

1- Physical barriers
The complex branching structure of LRT prevents larger particles from getting into lungs. Only particles 2 micrometers in diameter can reach alveoli
2- Clearance mechanisms
Lining of trachea and bronchi is maintained by a mucociliatry escalator.
Particles which enter in lungs get trapped in mucus which is moved upwards by cilia out of the lungs
3- Immune cells
Alveolar macrophages
B cells and T cells elicit localised responses
Complement proteins
Alveolar lining fluid contains surfactant, antibodies
Antimmicrobial peptides secreted by epithelial cells

Question 17

Risk factors for CAP in children

Answer 17

Age
Prematurity
Malnutrition
Pre-existing infections like HIV
Parental smoking
Exposure to environmental factors such as air prollution
Living in crowded space - more transmission

Question 18

Risk factors for CAP in adults

Answer 18

Age >65 greater risk
Gender- men higher at risk compared to women
Co-morbidities- CoPD, diabetes, CVD
Immunocompromised individuals
Smoking
High alcohol consumption
Smoking
Higher at risk of underweight

Question 19

Define immunosenescence

Answer 19

This refers to gradual deterioration of the immune system with age which increases sueceptibility to infectious diseases

Question 20

What are hallmarks of immunosenescence

Answer 20

1- Reduction in the number of peripheral blood naive cells (T and B lymphocytes)
2- Reative increase in frequency of memory cells- immune system becomes less flexible, stuck preparing for past infections instead of adapting to new ones
3- Inflammageing - increase in inflammatory mediators e.g C reactive protein and IL-6

Question 21

Define pertussis

Answer 21

• Bacterial infection caused by bordetella pertussis
  Causes severe coughing fits

It doesn’t invade lung tissue but causes irritation of respiratory epithelial cells via toxin secretion. This causes inflammation and leads to bronchopneumonia.

Question 22

What are symptoms of perstussis

Answer 22

Intense, repetitive coughing fits ending in whoop
Cold, fever, vomiting and loss of appetite

Question 23

How is pertussis transmitted

Answer 23

Inhaling infected droplets
is highly infectious, 50% mortality rate in children of 3 months
Most deaths due to complications (pneumonia) rather than the disease itself

Question 24

How is whooping cough prevented and treated?

Answer 24

There is little response to antimicrobials in vivo but treatment sometimes alleviates symptoms if caught at early stage
Immunisation

Question 25

TB is caused by which bacteria

Answer 25

Mycobacterium tuberculosis Spread through airborne droplets Causes damage to the lungs , leading cause of coughing

Question 26

Why have TB cases increased over the years

Answer 26

~ Due to the increase in homeless in large cities ~ poor nutrition, living conditions ~Increase in no of HIV and AIDS patients ~emergence of multi drug resistant tuberculosis (MDR TB)

Question 27

How is standard TB (not resistant) treated?

Answer 27

course of 4 antimicrobials drugs for 6 months

Question 28

What is MDR TB resistant to?

Answer 28

Rifampicin Isoniaizid 2 most effective first line anti-TB drugs

Question 29

The emergence of MDR TB is due to:

Answer 29

incomplete therapy Latent infection and re-infect Long term care facilities and correlational facilities

Question 30

What is second-line treatmentfor MDR TB?

Answer 30

2nd line treatment is limited and requires extensive chemotherapy with medicines which are expensive and toxic In some cases, more severe drug resistance can develop. Bacteria do not respond to 2nd line treatments leaving patients without any further treatment.

Question 31

Latent TB

Answer 31

means that person has latent TB but there are no symptoms and they cannot treansmit infection Immunucompromised individuals, malnutrition, diabetes or people who use tobacco are at higher risk of falling ill. When a person develops active TB, it may take months for symptoms to appear therefore leading to delays in treatment and higher result of transmission People with HIV are more likely to develop active TB

Question 32

What is cost of tb prevention, diagnosis and treament

Answer 32

US $13 billion are needed for Tb prevention, diagnosis and treatment and care to achieve global tragets set by UN

Question 33

What is BCG vaccine

Answer 33

the only available vaccine as of 2024 derived from weakened strain of mycobacterium bovis. In children it decreases the risk of getting infections by 20% and risk of infection turning into active disease by nearly 60% The immuny it induces decreases after 10 years

Question 34

What's the issue with useing BCG vaccine?

Answer 34

TST test i used to check for TB exposure by injecting tuberculin under the skin + results indicate prior infection to TB CBG vaccine causes false positive results of this test. This reduces the usefulness of screening tool

Question 35

What are some new vaccines for TB

Answer 35

1 - Recombinant CBG 30 Engineered to overexpress Antigen 85B, major immunodominant protein in TB. This antigen elicits a strong T cell- response, especially in CD4 and CD8 cells Phase 1 trials demonstrated vaccine was safe and immunogenic – significantly increased Antigen 85B-specific immune responses (memory CD4+ and CD8+ T cells, IFN-g response, ability of T cells to activate macrophages to inhibit intracellular multiplication of mycobacteria 2- 72 fusion protein vaccine Triggers a targeted immune response without using live bacteria or viruses. fusion of two MTP proteins. Trial status: Completed Phase I trials in 2005 Result: Shown to be safe and immunogenic (i.e., able to stimulate an immune response), but further development has been slower

Question 36

What is the treatment and prevention for Pneumonococcus?

Answer 36

Antibiotics- amoxicillin commonly used Immunisation against Hib, pneumonoccos and whooping cough and measles is the most effective way in preventing pneumoniae. Adequate nutrition - exclusive breastfeeding for first 6 months of life Addressing environmental factors like indoor air pollution and encouraging good hygiene in crowded homes

Question 37

Which antibiotic is given to decrease the risk of contracting pneumonia in children with HIV infection

Answer 37

Cotrimoxazole

Question 38

Steptococcus pneumoniae

Answer 38

Gram positive coccus Causes CAP Causes infections at all levels of respiratory tract Also a commensal in nasopharynx Many different subtypes with different virulences

Question 39

What does pneumonococcus cause

Answer 39

otitis media, pneumonia, sepsis and meningtitis (result of breach in RT infections)

Question 40

What immunisation is available to prevent infection caused by pneumonococcus ?

Answer 40

Pneumonococcal conjugate vaccine which is given to babies, childrens and adults. Offers protection against 13 serotypes of pneumonoccus. Serotype replacement – expansion of non-vaccine serotypes as a result of the removal from the population of vaccine types that compete with them to colonise new hosts – particularly serotypes 6A, 19A, and 15B/C

Question 41

S. aureus

Answer 41

gram positive coccus Causes HAP Causes severe illness with high mortality rates Often occurs secondary to influenza Infection may reach lungs via bloodstream when it arises from contaminated IV drug use

Question 42

S.aureus releases toxins which can cause

Answer 42

necrosis

Question 43

Standard treatment of S.A?

Answer 43

B-lactamase resistant pinicillin antibiotics

Question 44

Whats the issue associated with Staph.aureus

Answer 44

Resistant leading to MRSA

Question 45

Other than pneumoniae, what infections does S.aureus cause

Answer 45

toxic shock syndrome, sepsis, infective endocarditis (heart condition) and soft tissue infections

Question 46

Hib

Answer 46

Gram- negative bacilli Virulent strains are encapsulated 6 subtyes Hib - most important virulent capsulated form Causes epiglottitis, bacteraemia and mingetis and pnuemonia

Question 47

Is there a vaccine for Hib and what does it do?

Answer 47

yes- given to high risks groups like children to reduce risk of meningitis Provides protection against epiglottitis

Question 48

Treatment for HIB

Answer 48

Antibiotics - amoxicyliin but more resistant strains require alternative antibiotics such as co-amoxyclav, trimethrprim

Question 49

Klesbsiella pneumoniae

Answer 49

Capsulated gram - HAP Causes disease in individuals who have impaired resisatnce to infection or lung disease. Causes severe infection- destrcution of lung tissue, caviation and abcess formation. Its pathogencicty is attributed to production of endotoxin (LPS)

Question 50

Where is K.pneumoniae present and what's the treatment for it

Answer 50

present in catherised patients 3rd generation cephalosporin with an aminoglycoside

Question 51

Pseudomonas aureginosa

Answer 51

gram - bacillus HAP Common cause of pneumonia in hospitalised patients Considered to be opputunistic pathogen which arises as a result of weaked immunit or due to other ilnesses

Question 52

Treatment of P.aureginosa

Answer 52

combination of aminoglycoside and 3rd generation cephalosporin and anti-pseudomonal penicillin

Question 53

serotype replacement

Answer 53

When people are vaccinated with a vaccine like Prevnar13, the serotypes included in the vaccine (e.g., 1, 3, 4, 6B, 14) become less common in the population because vaccination reduces the ability of these bacteria to colonize hosts (people). However, serotypes not included in the vaccine (like serotypes 6A, 19A, and 15B/C) can expand in prevalence because there is less competition from the vaccine-covered serotypes.

Question 54

Respiratory synctial virus

Answer 54

Single stranded RNA virus most common cause of respiratory hospitalisation in infants and can cause reinfection in all groups, though older children and adults symptoms may be less severe

Question 55

When are the infection rates higher for Syncytial virus and what does it lead to in children, adults and elderly

Answer 55

during winter months cause bronchiolitis (affects bronchioles, leading to inflammation) in children common colds in adults more serious repsiratory illnesses such as penumonia in elderly particularly those who are immunocompromised

Question 56

How is RSV spread

Answer 56

through contaminated air droplets so when an infected person coughs or sneezes, virus spreads to nearby individuals. Can cause both community acquired and hospital acquired infections

Question 57

Mechanism of RSV

Answer 57

RSV typically enters the body through the eyes or nose (the mucosal surfaces), where it then infects the epithelial cells of the upper and lower airways (nose, throat, and lungs). Infection leads to inflammation, cell damage, and airway obstruction, which is particularly problematic for infants and individuals with already compromised respiratory systems. The obstruction occurs due to swelling of the airways, mucus production, and syncytia formation, all of which contribute to difficulty breathing. In infants, this can lead to the severe respiratory condition called bronchiolitis, which involves inflammation and congestion in the smaller airways (bronchioles), resulting in wheezing and difficulty breathing.

Question 58

treatment for RSV?

Answer 58

there is currently no vaccine

Question 59

Influenza virus

Answer 59

single stranded RNA virus symptoms range from mild to severe including fever, runny nose, sore throat, muscle pain, headache, coughing, fatigue. Diarrhoe and vomiting may occyur in children

Question 60

How is influeza transmitted

Answer 60

1- through respiratory droplets produced from coughing and sneezing 2- can also be transmitted through aerosols which are smaller respiratory droplets and remain suspended in air for a longer period of time. 3- can be transmitted through fomites Fomites are objects or surfaces that can become contaminated with viruses when an infected person touches them, coughs, or sneezes onto them. If someone else touches these contaminated objects or surfaces (e.g., door handles, countertops, or smartphones) and then touches their mouth, nose, or eyes, they can introduce the virus into their body, leading to infection.

Question 61

which is the most common subtype of influenza virus

Answer 61

A- widespread in humans and pigs. has caused pandemics due to its ability to undergo genetic mutations and ability to infect both humans and animals B- causes illnesses in humans but not pandemics like type a Type C - associated with mild infections

Question 62

Type A is classified into subtyoes based on what?

Answer 62

viral proteins like haemagluttinin and neuraminidase as of 2019, 18 H subtypes and 11 N subtypes have been identified.

Question 63

Through which process do influenza viruses evolve

Answer 63

antigenic drift antigenic shift

Question 64

Antigenic Drift

Answer 64

hen an influenza virus's antigens change due to the gradual accumulation of mutations in the antigen's (HA or NA) gene. This can occur in response to evolutionary pressure exerted by the host immune response. Antigenic drift is especially common for the HA protein, in which just a few amino acid changes in the head region can constitute antigenic drift. The result is the production of novel strains that can evade pre-existing antibody-mediated immunity. Antigenic drift is a major cause of seasonal influenza, and requires that flu vaccines be updated annually.

Question 65

Antigenic shift

Answer 65

sudden, drastic change in an influenza virus's antigen, usually HA. During antigenic shift, antigenically different strains that infect the same cell can reassort genome segments with each other, producing hybrid progeny. Since all influenza viruses have segmented genomes, all are capable of reassortment. Can only occur among influenza viruses of the same genus and most commonly occurs among IAVs. Pigs, bats, and quails have receptors for both mammalian and avian IAVs, so they are potential "mixing vessels" for reassortment. If an animal strain reassorts with a human strain, then a novel strain can emerge that is capable of human-to-human transmission