CPC 2 - Haemoptysis Flashcards
What is the commonest bacterial cause of CAP?
Strep pneumoniae
What are the risk factors for CAP?
Extremes of age
Impaired gag reflex/mucociliary escalator
Non-functioning or no spleen
Impaired immunity
Chronic medical conditions of liver, heart, lung
Smoking or alcoholism
What are the treatments of choice for CAP?
Beta-lactam antibiotic +/- macrolide
eg. Amoxicillin or co-amoxiclav +/- clarithromycin
What are some things one must consider before beginning treatment for CAP?
CURB-65 severity score to guide treatment (>/= 2 requires admission to hospital/ IV antibiotics)
Antibiotic allergies
Local antibiotic susceptibility patterns
Avoid cephalosporins to prevent C. difficile associated diarrhoea
Which organisms can be associated with cavitation and haemoptysis?
Aspergillus fumigatus
Klebsiella penumoniae
Mycobacterium tuberculosis
Staph aureus
What is Aspergillus lung infection and what types are there?
A fungal infection
Three types:
Allergic pulmonary aspergillosis (associated with asthma)
Aspergilloma (fungal balls in patients with pre-existing lung cavities eg. following TB)
Invasive pulmonary aspergillosis (immunosuppression with impaired neutrophil function; high mortality)
What is community-acquired Klebsiella Pneumonia?
Gram-ve bacilli
Affects debilitated older patients with alcoholism
Production of sputum described as “red currant jelly”
Causes acute necrotizing pneumoonia
Affects upper lobes
High mortality rate (50%) even with antimicrobial therapy
Which organisms would not be treated with a beta lactam?
The following two are examples of organisms with no cell wall, hence not susceptible to beta lactams:
Chlamydophyla pneumoniae
Mycoplasma pneumoniae
What is S. aureus Pneumonia?
Primary pneumonia associated with Panton Valentine leucocidin (PVL)
Secondary post-viral pneumonia
Causes necrotising pneumonia with cavitating lesions and lung abscesses
How is TB transmitted?
Person to person spread
Inhalation of respiratory droplets
Prolonged close contact
Increased risk of transmission with highly infectious host or highly susceptible contact
What are some host factors for TB?
Previous exposure - BCG Extremes of age Nutritional status Living conditions Other medical conditions (DM, damaged lungs (eg. silicosis)) Immunosuppression (steroids, HIV)
What are some environmental factors for TB?
Endemic infection
Homeless
Drug and alcohol misuse
Imprisonment
What is the pathogenesis of TB?
Primary infection (ineffective immune response):
The bacilli are taken up and multiply in the alveolar macrophages
Macrophages are transported to local (hilar) lymph nodes
T cells are sensitised
Type 1 cytokines (IL-2, Interferon Gamma, TNF alpha) cause accumulation of macrophages/histiocytes
Granuloma formation in lung and lymph node:
Granuloma undergoes necrosis and some bacilli die
Reactivation or re-infection:
Extensive tissue necrosis - apex of lung
Cavitation
Spread to other sites
How can a lower respiratory tract infection be diagnosed?
Sterile site sample microscopy, culture, sensitivity (MCS) - blood, pleural fluid, biopsy
Non-sterile sample MCS (sputum; non-bronchoscopic blind sampling of lower airway; bronchoscopic methods eg. broncho-alveolar lavage)
Lung biopsy
Antigen detection using immunoassays, latex agglutination and molecular tests (eg. PCR)
How can TB be diagnosed?
Microscopy: Ziehl Neelsen (ZN) stain Auramine phenol (AP) stain with fluorescent microscope
Culture:
Solid media eg. Lowenstein-Jensen
Liquid media eg. Kirschner’s medium
Automated systems
Molecular methods:
PCR
DNA probes
Allows identification, resistance detection, and typing
