Microbiology 12: Respiratory Tract Infections Flashcards
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
List the 3 most common causative organisms of pneumonia in neonates 0-1 months old ?
E.coli
Group B streptococcus (GBS)
Listeria monocytogenes
List the 3 most common causative organisms of pneumonia in children 1-6 months old ?
Chlamydia trachomatis
Staphylococcus aureus
RSV
List the 2 most common causative organisms of pneumonia in children 6 months - 5 years old ?
Mycoplasma pneumonia
Influenza
List the 2 most common causative organisms of pneumonia in people ages 16-30 years old ?
Streptococcus pneumonia
Mycoplasma pneumonia
List the 2 typical organisms causing CAP
Streptococcus Pneumoniae
Haemophilus influenza
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
List 3 organisms that cause cavitation on CXR ?
Staph aureus (Swiss cheese type pattern)
Klebsiella pneumonia
TB
Which atypical organism is transmitted by inhalation of infected water droplets e.g from saunas, AC and is grown on buffered charcoal yeast extract ?
Legionella Pneumophila
What is the antibiotic treatment for atypical CAP ?
Macrolide - Azithromycin/ clarithromycin
+
Doxycycline
An auramine stain and ziehl-Nielsen stain are used to identify which organism ?
TB
What are the most common causative organisms of HAP ?
Enterobacteriaciae (e.coli, klebsiella pneumonia)
S.aureus
Pseudomonas aeruginosa
Which organisms causes bilateral ground glass shadowing (bat’s wing appearance)?
Pneumocystis Jirovecii (PCP)
What is a special physical test to diagnose Pneumocystis jirovecii ?
The walk test (attach oxygen saturation and get them to walk) - shows desaturation on exertion
Which organisms causing LRTIs are more common in patients with neutropenia ?
Fungi - aspergillus
Which organism typically causes LRTIs in patients with bone marrow failure ?
CMV
What is the 1st line antibiotic treatment for HAP ?
Ciprofloxacin +- vancomycin
Which atypical organism causes Pneumonia with cold agglutinins And erythema multiforme (target lesion) on palms ?
Mycoplasma Pneumonia
Which organism causes a pneumonia with cough, myalgia and rose spots on the abdomen and is commonly seen in ornithologists (bird handlers)?
Chlamydia Psittaci
Which organism causes pneumonia with target shaped lesions on the palm ?
Mycoplasma pneumonia
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
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 compromises to respiratory function cause respiratory diseases
poor swallow abnormal ciliary function abnormal mucus dilated airways defects in host immunity
features of strep pneumoniae
alpha-haemolytic and optochin sensitive
gram positive cocci
severe pneumonia, fever + rigors, lobar consolidation
almost always penicillin sensitive
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
viruses
strep pneumoniae
hemophilus influenzae
moraxelle catarrhalis
features of haemophilus influenzae
gram-negative cooco-bacilli
common with pre-exisiting lung disease
may produce beta-lactamase
features of legionella pneumophilia
spread via inhalation of infected water droplets
grown on buffered charcoal yeast extract
can cause multi-organ failure
features of legionella pneumophilia
aerosol spread environmental outbreaks confusion, abdo pain, diarrhoea lymphopaenia, hyponatraemia inv = urinary antigens sensitive to macrolides
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
why are empyemas difficult to treat
they have a wall around them and the pus contained is very acidotic which inactivates the antibiotics
stains for TB
auramine stain
ziehl-neelsen stain (auer rods are the acid-fast bacilli)
what is a HAP
pneumonia onset >48 hrs in hospital
features of pneumocyctic jirovecii
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
features of aspergillus fumigatus
ABPA: chronic wheeze, eosinophilia, bronchiectasis
Aspergilloma: fungal ball, often in pre-existing cavities
Invasive aspergillosis: immunocompromised, tx = amphotercin B
LRTI in HIV patients
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
legionella pneumophilia
strep pneumoniae
what would you use antibody tests for
chlamydia
legionella
what colour are gram +ve and gram -ve bugs
gram +ve = blue
gram -ve = prink
treatment for mild-moderate CAP
amoxicillin
or erythromycin/clarythromycin
treatment for moderate-severe CAP
co-amoxiclav
and clarythromycin
(allergic - give cefuroxime + clarythromycin)
treatment for HAP
1st line = ciprofloxacin +/- vancomycin
2nd line = piptazobactam + vancomycin
MRSA = vancomycin
pseudomonas = piptazobactam OR cipro +/- gentamycin
how can we prevent pneumonia
smoking advice
vaccination - inlfuenza anually, pneumovax every 5 yrs
