Microbiology 7S RTIs Flashcards
what does a double heart border/ Sail sign on CXR suggest
Left lower lobe collapse
3 results on investigation which point towards S.pneumonia
Alpha haemolytic (green)
Optochin sensitive
High virulence
gram +ve cocci
Clinical features classically seen in Strep pneumonia
Rusty coloured sputum
Lobar pneumonia
Name a high virulent and low virulent Streptococcus strain
High virulence: Strep pneumonia
Low virulence: Strep viridans
most common cause of CAP
S.pneumonia
Main organisms involved in cAP
S.pneumonia Haemophilus influenza Klebsiella mORAXella S.aureus
4 main organisms causing atypical pneumonia
Legionella
Mycoplasma
Coxiella burnetii (Q fever)
Chlamydia
2 features of Coxiella burnetii (Q fever)
faRM ANImals
Hepatitis
splenomegaly, rash, haemolytic anaemia, bird exposure
Chlamydia psittaci
3 organisms which often cause cavitating lesions on CXR
S.aureus
TB
Klebsiella
3 most common causative organisms of pneumonia in 1-6 month old?
Chlamydia trachomatis
RSV
S.aureus
CURB-65?
Criteria for admission
Confusion Urea >7mmol/L RR >30 BP <90/60 <65 years
1 = oral amoxicillin at home 5 days 2 = consider admission 3-5 = SEVERE, admit +/- ITU co-amox + clari
what is the definition of bronchitis?
Inflammation of medium sized vessels
CXR in bronchitis
NORMAL
cause of pneumonia in pt with pre-existing lung disease + smoker, gram negative coccobacili
H.influenza
which bacterium is grown on a cHARCOAL YEAST EXTRACT
Legionella pneumophilia
urinary antigens seen in pneumonia caused by which 2 organisms?
Legionella + streptococcus pneumonia
which organisms cause atypical pneumonia?
Legionella
Mycoplasma
CHlamydia
Coxiella
Why can atypicals not be treated with penicillins?
The organisms DO NOT HAVE CELL WALLS therefore need to be treated with antibiotics which disrupt protein synthesis e.g. macrolides or tetracyclines
what is characteristic of atypical pneumonia?
Extra-pulmonary manifestations e.g. hepatitis
how is coxiella burnetti transmitted?
aerosol or milk (farm animals0
which part of the lung does TB have a predilection for?
Upper zones
which 2 stains are used in TB?
Auramine stain and Ziehl-Neelsen
definition of HAP
A pneumonia with onset >48 hours post admission
main causative organisms in HAP
Enterobacteriacae e.g. E.coli, Klebsiella
S.aureus
Pseudomonas
• 64 year old, treated for lymph node TB, increasing SOB over one month, non-productive cough and bilateral-ground glass shadowing on CT (“bats wings”)
Pneumocystic jirovecii pneumonia (PCP)
what type of organism is pneumocystis jirovecii?
FUNGUS
useful investigation for pCP
Walk test will show desaturation on exertion
Prophylaxis and treatment for PCP
Co-trimoxazole (septrin)
3 main conditions caused by aspergillus fumigatus
Allergic bronchopulmonary aspergillosis (ABPA)
Aspergilloma (pre-existing cavity)
Invasive aspergillosis (immunocompromised)
Treatment for invasive aspergillosis
Amphotericin B
neutropenia –> prone to which LRTIs?
Fungi, especially aspergillus
Splenectomy –> ?LRTIs
S.pneumonia, Haemophilus, neisseria + malaria
when can antibody test be used in diagnosis of pneumonia?
only if there is a paired sample i.e. a sample when the patient was well
investigations to detect PCP
Immunofluorescence + SILVER STAIN
SILVER STAIN
PCP
CAP empirical therapy for mild-mod and mod-severe
Mild - mod: oral amoxicillin
Mod-severe: Co-amoxiclav (augmentin) + clarithromycin
HAP empirical therapy 1st line + 2nd line/ITU
1st line = ciprofloxacin + vancomycin
2nd = piptazobactam + vancomycin
specific therapy for pseudomonas
piptaz OR cipro +/- gentamicin
