Microbiology 4 - Respiratory tract infection

Question 1

What is the most likely causative organism in a young patient with a lower lobe pneumonia, raised WCC and CRP?

Answer 1

Strep pneumoniae

Question 2

Recall the appearance of streptococcus in culture

Answer 2

Gram positive cocci in chains

Question 3

Recall how streptococcus pnuemoniae is identified in the lab

Answer 3

Demonstrates alpha haemolysis

alpha haemolysis: strep pnuemoniae (optochin sensitive), strep viridans (not optochin sensitive)

beta haemolysis: GAS (Bacitracin sensitive), GBS (Not bacitracin sensitive)

Question 4

What is the most common pathogen implicated in CAP?

Answer 4

Streptococcus

Question 5

Is streptococcus gram pos or gram neg?

Answer 5

Gram pos

Question 6

Recall the 2 pathogens that can cause typical CAP

Answer 6

S. pneumonia

H influenzae

Question 7

Which investigation are indicated in suspected CAP?

Answer 7

FBC, U&E, CRP, LFT

Blood cultures, sputum MC&S

Question 8

What severity score can be used to score CAP?

Answer 8

CURB-65
Confusion
Urea (>7)
RR (>30)
BP (<90 systolic)
>65 years
Score 2 or above = admit

Question 9

What is bronchitis?

Answer 9

Inflammation of medium sized airways

Question 10

How does bronchitis appear on CXR?

Answer 10

Normal

Question 11

How do haemophilus influenzae appear under the microscope?

Answer 11

Gram neg cocco-bacilli

Question 12

On what sort of agar should H influenzae be cultured?

Answer 12

Chocolate agar

Question 13

What colour sputum is produced in Strep pneumoniae?

Answer 13

Rusty

Kelbsiella: red colour

psuedomonas, H.influenzae: green colour

Question 14

Which type of atypical pneumonia is associated with hyponatraemia?

Answer 14

Legionella

Question 15

What is the special culture required for legionella?

Answer 15

Buffered charcoal yeast

Question 16

What extrapulmonary features are likely in atypical pneumonia?

Answer 16

Hepatitis

Hyponatraemia

Question 17

Which type of pneumonia is associated with confusion, abdo pain and diarrhoea?

Answer 17

Legionella

Question 18

Which type of pneumonia is spread by birds?

Answer 18

Chlamydia psittaci

Question 19

What is an empyema?

Answer 19

A collection of pus in the pleural cavity, gram-positive, or cultured from the pleural fluid

Question 20

What are the key features of TB pneumonia?

Answer 20

Ethnicity
Prolonged prodrome
Fevers
Weight loss
haemoptysis

Question 21

Recall 2 stains that can identify TB

Answer 21

Auramine(auramine-rhodamine) stain
Ziehl-Neelsen stain

Both of these are acid-fact bacilli testing stains

Question 22

How can upper and lower respiratory flora be differentiated?

Answer 22

Bronchial lavage

Question 23

Which type of pneumonia is common in the immunosuppressed (eg people who have had TB, HIV)?

Answer 23

Pneumocystis jirovecii

Question 24

Recall 4 symptoms of pneumocystis pneumonia

Answer 24

Dry cough
Weight loss
SOB (exertional dyspanea- after walking like 10m)
Malaise

treat with co-trimoxazole

Question 25

Recall the typical CXR finding in pneumocystis pneumonia

Answer 25

Bat wing

Question 26

What is the most likely cause of pneumonia when there are interstitial changes on CT, neutropaenia and a history of ABx treatment?

Answer 26

Aspergillus fumigatus This is particularly associated with prolonged ABx use - if ABx hasn't worked it may have a fungal cause Also common in severely immunosuppressed patients, eg on chemotherapy

Question 27

Which type of LRTI is more common in people who have had a BM transplant?

Answer 27

CMV

Question 28

Which pneumonia pathogens can be tested for in urine?

Answer 28

Legionella | S pneumoniae

Question 29

Which type of atypical pneumonia are those who work around farm animals at increased relative risk of?

Answer 29

Coxiella burnetti

Question 30

What colour does gram stain appear with gram pos/gram neg bacteria?

Answer 30

Gram pos: blue | Gram neg: pink

Question 31

What is the treatment for mild-moderate pneumonia?

Answer 31

Amoxicilin

Question 32

What is the first line treatment for HAP?

Answer 32

Ciprofloxacin +/- vancomycin If severe: Tazocin (same thing as pip-tazo (piperacilin + tazobactam) + vanc Aspiration: tazocin + Metronidazole

Question 33

What type of antobiotic is coxiella burnetti (Q fever) pneumonia sensitive to?

Answer 33

Macrolides

Question 34

How will CXR appear in bronchitis?

Answer 34

Normal

Question 35

Which pathogen is the most likely cause of a post-influenza pneumonia?

Answer 35

S aureus

Question 36

Which pneumonia-causing pathogen is associated with smoking?

Answer 36

M catarrhalis

Question 37

Which pathogen is associated with the cause of pneumonia in the alcohol-dependent and the elderly?

Answer 37

Klebsiella

Question 38

Which pathogen is associated with the cause of pneumonia in patients with pre-existing COPD?

Answer 38

Haemophilus influenza

Question 39

Which type of pneumonia gives a positive cold agglutinin test?

Answer 39

Mycoplasma pneumonia

Question 40

Which type of pneumonia may present with erythema multiforme?

Answer 40

Mycoplasma pneumonia

Question 41

Which stain can be used to detect PCP, and what shape would the organisms appear?

Answer 41

Silver stain (Gomari's methamine silver) Boat-shaped organisms May also show "flying saucer cysts" Co-trimoxazole can be used to treat PCP

Question 42

How can chlamydia pneumonia be diagnosed?

Answer 42

PCR of TWAR (Taiwan acute respiratory agent) agent

Question 43

How can PCP be diagnosed in the lab?

Answer 43

Gomori’s methanamine silver stain in cytology lab Shows boat-shaped/flying saucer shaped organisms Pneumocystis Jirovecii is a yeast like fungus

Question 44

What are some examples of typical and atypical causes of CAP

Answer 44

Typical: Strep pnuemoniae Haemophilis influenzae Moraxella catarrhalis Atypical: ``` Legionella Pneumophila (Causes hyponatreamia) Mycoplasma pneumoniae (Causes erythema multiforme, positive cold agglutinin test) Chlamydia pneumoniae ```

Question 45

Some examples of HAP

Answer 45

E.coli Klebsiella MRSA Pseudomonas Order of prevelance

Question 46

Which types of pneumonia pathogens cause cavitating lesions

Answer 46

Klebsiella Staph aureus TB

Question 47

What can be used to treat PCP?

Answer 47

Co-trimoxazole (sulfomethoxazole-trimethoprim)