Microbiology 12: Respiratory Tract Infections

Question 1

Blood culture from a young women isolates a gram +ve diplococcus, alpha-haemolytic bacteria which is optochin sensitive.

What is the most likely causative organism of her pneumonia?

Answer 1

Streptococcus. Pneumoniae

Question 2

List the 3 most common causative organisms of pneumonia in neonates 0-1 months old ?

Answer 2

E.coli
Group B streptococcus (GBS)
Listeria monocytogenes

Question 3

List the 3 most common causative organisms of pneumonia in children 1-6 months old ?

Answer 3

Chlamydia trachomatis
Staphylococcus aureus
RSV

Question 4

List the 2 most common causative organisms of pneumonia in children 6 months - 5 years old ?

Answer 4

Mycoplasma pneumonia

Influenza

Question 5

List the 2 most common causative organisms of pneumonia in people ages 16-30 years old ?

Answer 5

Streptococcus pneumonia

Mycoplasma pneumonia

Question 6

List the 2 typical organisms causing CAP

Answer 6

Streptococcus Pneumoniae

Haemophilus influenza

Question 7

List the 4 atypical organisms causing CAP

Answer 7

Legionella
Mycoplasma
Coxiella burnetii (Q-fever)- exposed to farm animals
Chlamydia psittaci (psittacosis)- exposure to birds, you get a haemolytic anaemia

Question 8

List 3 organisms that cause cavitation on CXR ?

Answer 8

Staph aureus (Swiss cheese type pattern)
Klebsiella pneumonia
TB

Question 9

Which atypical organism is transmitted by inhalation of infected water droplets e.g from saunas, AC and is grown on buffered charcoal yeast extract ?

Answer 9

Legionella Pneumophila

Question 10

What is the antibiotic treatment for atypical CAP ?

Answer 10

Macrolide - Azithromycin/ clarithromycin
+
Doxycycline

Question 11

An auramine stain and ziehl-Nielsen stain are used to identify which organism ?

Answer 11

TB

Question 12

What are the most common causative organisms of HAP ?

Answer 12

Enterobacteriaciae (e.coli, klebsiella pneumonia)
S.aureus
Pseudomonas aeruginosa

Question 13

Which organisms causes bilateral ground glass shadowing (bat’s wing appearance)?

Answer 13

Pneumocystis Jirovecii (PCP)

Question 14

What is a special physical test to diagnose Pneumocystis jirovecii ?

Answer 14

The walk test (attach oxygen saturation and get them to walk) - shows desaturation on exertion

Question 15

Which organisms causing LRTIs are more common in patients with neutropenia ?

Answer 15

Fungi - aspergillus

Question 16

Which organism typically causes LRTIs in patients with bone marrow failure ?

Answer 16

CMV

Question 17

What is the 1st line antibiotic treatment for HAP ?

Answer 17

Ciprofloxacin +- vancomycin

Question 18

Which atypical organism causes Pneumonia with cold agglutinins And erythema multiforme (target lesion) on palms ?

Answer 18

Mycoplasma Pneumonia

Question 19

Which organism causes a pneumonia with cough, myalgia and rose spots on the abdomen and is commonly seen in ornithologists (bird handlers)?

Answer 19

Chlamydia Psittaci

Question 20

Which organism causes pneumonia with target shaped lesions on the palm ?

Answer 20

Mycoplasma pneumonia

Question 21

Which 2 organism commonly Infect people with cystic fibrosis ?

Answer 21

Pseudomonas aeruginosa

Burkholderia capacia

Question 22

Which organism when stained with Gomori’s methenamine silver stain shows “Flying saucer” shaped cysts ?

Answer 22

Pneumocystis jirovecii

Question 23

Which coccus bacteria arranges in grape-like clusters ?

Answer 23

Staphylococcus aureus

Question 24

Which organism causes acute exacerbation of COPD and otitis media in children ?

Answer 24

Moraxella Caterrhalis

Question 25

what compromises to respiratory function cause respiratory diseases

Answer 25

``` poor swallow abnormal ciliary function abnormal mucus dilated airways defects in host immunity ```

Question 26

features of strep pneumoniae

Answer 26

alpha-haemolytic and optochin sensitive gram positive cocci severe pneumonia, fever + rigors, lobar consolidation almost always penicillin sensitive

Question 27

what is the CURB-65 scale

Answer 27

``` risk stratification fro pneumonia patients confusion urea >7mmol/L RR>30 BP <90 systolic, <60 diastolic 65+ years ``` 2 = consider admitting 2-5 manage as severe pneumonia and consider ITU admission

Question 28

what organisms commonly cause bronchitis

Answer 28

viruses strep pneumoniae hemophilus influenzae moraxelle catarrhalis

Question 29

features of haemophilus influenzae

Answer 29

gram-negative cooco-bacilli common with pre-exisiting lung disease may produce beta-lactamase

Question 30

features of legionella pneumophilia

Answer 30

spread via inhalation of infected water droplets grown on buffered charcoal yeast extract can cause multi-organ failure

Question 31

features of legionella pneumophilia

Answer 31

``` aerosol spread environmental outbreaks confusion, abdo pain, diarrhoea lymphopaenia, hyponatraemia inv = urinary antigens sensitive to macrolides ```

Question 32

features of coxiella burnetii

Answer 32

common in domestic farm animals transmitted by aerosol or milk inv = serology sensitive to macrolides

Question 33

features of chlamydia psittachi

Answer 33

spread from birds by inhalation inv = serology sensitive to macrolides

Question 34

why are empyemas difficult to treat

Answer 34

they have a wall around them and the pus contained is very acidotic which inactivates the antibiotics

Question 35

stains for TB

Answer 35

auramine stain | ziehl-neelsen stain (auer rods are the acid-fast bacilli)

Question 36

what is a HAP

Answer 36

pneumonia onset >48 hrs in hospital

Question 37

features of pneumocyctic jirovecii

Answer 37

``` protozoan insidious onset presentation: dry cough, weight loss, SOB, malaise CXR: bat-wing shadowing inv: bronchoalveolar lavage tx: co-trimoxazole ``` detected by silver stain on cytology

Question 38

features of aspergillus fumigatus

Answer 38

ABPA: chronic wheeze, eosinophilia, bronchiectasis Aspergilloma: fungal ball, often in pre-existing cavities Invasive aspergillosis: immunocompromised, tx = amphotercin B

Question 39

LRTI in HIV patients

Answer 39

PCP TB atypical mycobacteria

Question 40

LRTI in neutropaenia

Answer 40

fungi (esp aspergillus species)

Question 41

LRTI in BM transplant

Answer 41

CMV

Question 42

LRTI in splenectomy

Answer 42

encapsulated organisms (S Pneumoniae, H influenzae, malaria)

Question 43

what would you use antigen tests for

Answer 43

legionella pneumophilia | strep pneumoniae

Question 44

what would you use antibody tests for

Answer 44

chlamydia | legionella

Question 45

what colour are gram +ve and gram -ve bugs

Answer 45

gram +ve = blue | gram -ve = prink

Question 46

treatment for mild-moderate CAP

Answer 46

amoxicillin | or erythromycin/clarythromycin

Question 47

treatment for moderate-severe CAP

Answer 47

co-amoxiclav and clarythromycin (allergic - give cefuroxime + clarythromycin)

Question 48

treatment for HAP

Answer 48

1st line = ciprofloxacin +/- vancomycin 2nd line = piptazobactam + vancomycin MRSA = vancomycin pseudomonas = piptazobactam OR cipro +/- gentamycin

Question 49

how can we prevent pneumonia

Answer 49

smoking advice | vaccination - inlfuenza anually, pneumovax every 5 yrs