Microbiology 12: Respiratory Tract Infections Flashcards by .. ...

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?

Streptococcus. Pneumoniae

NB since gram +ve, this would stian purple

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Blood culture finding if strept pneumoniae

purple stain (gram +ve)
a-haemolytic and optochin-sensitive

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

E.coli
Group B streptococcus (GBS)
Listeria monocytogenes

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

Chlamydia trachomatis
Staphylococcus aureus
RSV

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

Mycoplasma pneumonia
Influenza

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

Streptococcus pneumonia
Mycoplasma pneumonia

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List the 2 typical organisms causing CAP (85% of cases)

Streptococcus Pneumoniae
Haemophilus influenza

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List the 4 atypical organisms causing CAP

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

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List 3 organisms that cause cavitation on CXR ?

Staph aureus (Swiss cheese type pattern)
Klebsiella pneumonia
TB

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

Legionella Pneumophila

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What is the antibiotic treatment for atypical CAP ?

Macrolide - Azithromycin/ clarithromycin
+
Doxycycline

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

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What are the most common causative organisms of HAP ?

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

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

Pneumocystis Jirovecii (PCP)

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What is a special physical test to diagnose Pneumocystis jirovecii ?

What Ix can you do?

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

Ix: bronchoalveolar lavage

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

Fungi - aspergillus

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

CMV

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What is the 1st line antibiotic treatment for HAP ?

Ciprofloxacin +- vancomycin (these have gram -ve cover, which is important for HAP)

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

Mycoplasma Pneumonia

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

Chlamydia Psittaci

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

Mycoplasma pneumonia

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Which 2 organism commonly Infect people with cystic fibrosis ?

Pseudomonas aeruginosa
Burkholderia capacia

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

Pneumocystis jirovecii (PCP)

Which coccus bacteria arranges in grape-like clusters ?

Staphylococcus aureus

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

Moraxella Caterrhalis

what is the CURB-65 scale

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

what organisms commonly cause bronchitis (4)

* viruses * strep pneumoniae * hemophilus influenzae * moraxelle catarrhalis

features of legionella pneumophilia

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

features of coxiella burnetii

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

features of chlamydia psittachi

* spread from birds by inhalation * inv = serology * sensitive to macrolides

What is empyema? why are empyemas difficult to treat?

* bag of pus within the pleural cavity * they have a wall around them and the pus contained is very acidotic which inactivates the antibiotics

stains for TB (2)

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

what is a HAP

pneumonia onset \>48 hrs in hospital, typically on ventilation

Tx for Pneumocystic jiroveci pneumonia

Co-trimoxazole

3 types of aspergillus fumigatus

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

Tx of Aspergillus fumigatus

Liposomal Amphotericin B

LRTI in HIV patients (3)

* PCP * TB * atypical mycobacteria

LRTI in neutropaenia

fungi (esp aspergillus species)

LRTI in BM transplant

CMV

LRTI in splenectomy

encapsulated organisms (S Pneumoniae, H influenzae, malaria)

what would you use antigen tests for in pneumonia? (2)

legionella pneumophilia strep pneumoniae

what would you use antibody tests for in pneumonia (2)

* chlamydia * legionella These since they are difficult to culture

what colour are gram +ve and gram -ve bugs

gram +ve = blue/purple gram -ve = prink

treatment for mild-moderate CAP

* amoxicillin * or erythromycin/clarythromycin

treatment for moderate-severe CAP (2)

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

treatment for HAP

1st line = ciprofloxacin +/- vancomycin 2nd line = piptazobactam + vancomycin

30-50% of community acquired pneumonia due to what?

* ***Streptococcus pneumoniae***

What drug is strept pneumoniae always sensitive to?

Penicillin

Staph aureus features on CXR

* swiss cheese pattern * multiple cavities

3 causes of Cavitaties on CXR

* *Staphylococcus aureus* – get a swiss cheese pattern with multiple cavities * *Klebsiella pneumoniae* * TB

Haemophilus influenze causes what % of CAP? Which group of pts is it more common in? What do they look like on stain? What enzyme may they produce?

15-35% those with pre-existing lung disease Gram-negative cocci-bacilli (rod) - INCLUDE PIC beta-lactamase

3 atypical pneumonia sensitive to macrolides

* legionella pneumophilia * Coxiella burnetti * Chlamydia psittaci

Tx of MRSA

MRSA = vancomycin