13 Respiratory infections Flashcards
what is CAP
community acquired pneumonia:
pneumonia contracted by a person with little contact with the healthcare system
CAP is more common in (4)
males
the elderly
alcoholics and smokers- due to neutrophil response
chronic disease
what’s a preventative strategy for CAP
pneumococcal vaccination
describe the aetiology of CAP
conventional bacteria= 60-80% of all cases
atypical= 10-20%
viruses= 10-20%
give 2 examples of conventional bacteria causing CAP and 3 examples of atypical
c= S. Pneumoniae and H. Influenzae a= M. Pneumonia, C. Pneumoniae and L. Pneumophila
4 key stages in investigating CAP
confirm diagnosis
assess severity of disease
define aetiological agent (microbiological samples)
identify complications (like organ failure)
state 4 microbiological investigations in CAP
1 sputum analysis and culture
2 immunofluorescence on sputum samples
3 blood cultures
4 urinary pneumococcal and legionella antigen
severe CAP criteria
CRUB-65
confusion (mini-mental test score of 8 or less, new confusion)
urea >7mmol/l (since severe infection tends to impair renal function)
respiratory rate >30 per minute
blood pressure, systolic <90 or diastolic <60
65 or more years old
1 point for each that is present
scores of low-severity, moderate and severe CAP
low= 0 or 1 mod= 2 severe= 3 or more
describe low-severity CAP treatment
amoxicillin (500 mgs 4x a day for 5 days) or doxycycline (200 mgs then 100mg once a day)
if can’t take it orally= iv amoxicillin 500 mgs 3x a day
if severe penicillin allergy give ciprofloxacin 400 mgs 2x a day and vancomycin
describe moderate-severity CAP treatment
amoxicillin 500 mgs 4x a day for a week and clarithromycin 500 mgs 2x a day for a week OR doxycycline 200 mgs then 100 mg 1x a day
if can’t take orally= iv benzylpenicillin
if severe penicillin allergy give ciprofloxacin 400 mgs 2x a day and vancomycin
describe severe CAP treatment
co-amoxiclav 1.2g 3x a day and clarithromycin 500 mgs 2x a day iv for 10 days
IF severe penicillin allergy or suspected MRSA give levofloxacin 500 mgs 2x a day and vancomycin 1g 2x a day
treat for 10 days, extending to 14-21 for legionella, staphylococcal or gram negative pneumonia
describe mycoplasma and legionella
mycoplasma- in 45 years or less it occurs in epidemics, skin rashes appear before respiratory symptoms
legionella- occurs sporadically, usually middle aged men who smoke, can be transmitted through water systems, any severe pneumonia could be legionella, be suspicious
signs of pneumonia with influenza and treatment
hypoxaemia, severe dyspnoea (difficulty breathing)
oseltamavir 75 mgs 2x a day for 5 days, start without PCR results and can stop if negative
describe the TB life cycle
abscess produces aerosol, enters respiratory system, transmitted
invades into macrophages in respiratory tract, established intracellular infection
becomes a hypoxic environment, can’t sustain itself so in response to hypoxia genetic changes make it dormant
cytokines from inflammatory response can resuscitate TB after many years, leading to extracellular growth->high load
can’t eradicate dormant TB
where does TB reactivate
spine and kidneys
what are antimycobacterial agents
a diverse group of compounds, which are used either alone or in combination to treat Mycobacterium infections, including tuberculosis and leprosy
list 5 antimycobacterial agents
rifampin isoniazid ethambutol streptomycin pyrazinamide
describe rifampicin
mycobacterial RNA polymerase
bactericidal
quite toxic, affects contraceptive pill
describe isoniazid
inhibits cell wall mycolic acid synthesis
rapid and bactericidal effect
pyridoxine supplements can prevent peripheral neuropathy
describe pyrazinamide
mechanism of action entirely unknown
plays a key role in sterilising inflammatory tissue
describe ethambutol
inhibits synthesis of cell wall polysaccharides
side effect= optic neuritis
4th commonly used
only give to someone who understands and can report optic neuritis- colour changes etc
describe streptomycin
binds to mycobacterial ribosome and inhibits protein synthesis
bactericidal
side effect= ototoxicity
given parenterally (not oral)
describe 2-phase therapy
therapy can be divided into
1 an initial bactericidal phase in which the majority of organisms are killed
2 and a sterilising phase in which persisting organisms are eliminated
describe duration of therapy to cover phases of infection and resistance
4 agents for 2 months
then 2 agents for 4 months
standard anti TB therapy
rifampicin, isoniazid, pyrazinamine and ethambutol for 2 months
then rifampicin and isoniazid for 4 months
RIPE
what’s the biggest driver of drug resistance and how can it be combated
patients not completing the whole course
DOT programmes use a nurse or surrogate to directly observe all doses being taken
most common pattern of drug resistant TB
isolated isoniazid resistance
those at risk of drug resistant TB (5)
previously treated for TB
known contact with a case of drug resistant TB
acquisition of infection in a country of group with a high prevalence of drug resistance
patients who fail to make a satisfactory response to conventional treatment
co-existing HIV infection
treatment in drug resistant TB
4 drugs which the organism is likely to be sensitive to
continue until 3-6 months after the sputum becomes culture negative
continued with 3 drugs for 15-18 months
surgery may be necessary
what pressure should the side room be in TB
negatively ventilated
