Microbiology Flashcards
what is the clinical presentation of influenza?
fever: high, abrupt onset malaise myalgia headache cough (initially dry, painless- becomes productive and painful) prostration (extreme physical weakness)
what are the 2 important types of classical flu?
influenza A
influenza B
what is haemophilus influenzae?
a Gram-negative, aerobic, small bacilli
how is influenza transmitted?
droplets or direct contact with infected respiratroy secretions
what are the 5 major complications of influenza?
- primary influenza pneumonia
- secondary bacterial pneumonia
- bronchitis
- otitis media
- pregnancy complications
what is otitis media?
infection of the middle ear
what type of complications can occur if patient gets influenza during pregenancy?
perinatal mortality
prematurity
smaller neonatal size lower birth weigh
what is the treatment of flu?
bed rest
fluids
paracetamol
when should antivirals be given in the treatment of flu?
only when patient iss at risk of complications
what is an antigenic drift?
minor mutations in the antibody binding sites
what is an antigenic shift?
process by which 2 or more different strains of virus combine to form a new subtype having a mixture of the surface antigens
what types of influenzae can go through antigenic drift?
influenza A
influenza B
what types of influenzae can go through antienic shift?
influenza A only
what type of mutations to the influenzae virus cause epidemics?
antigenic drifts
influeza A or B
what type of mutations to the influenzae virus cause pandemics?
antigenis shift
segmented genome
animal reservoi/mixing vessel
(influenza A only)
what is the name of the H1N1 sub type of influenzae A?
swine flu
what is the best way for direct detection of the influenza virus?
PCR using nasopharyngeal/throat swabs or other respiratory samples
what is an indirect way to detect the influenza virus?
antibody detection
what 2 types of vaccines used for the prevention of flu?
killed vaccine
live attenuated vaccine
who is the killed influenza vaccine given to?
adult patients at risks of complications
health care workers
children 6 months - 2 years at risk of complications
(annually)
who is the live attenuated vaccine given to?
offered to
all children 2-5
all primary school children
(because live attenuated vaccine more effective in children 2-17 than killed vaccine)
how is the live attenuated vaccine given?
intra-nasally
what bacteria are known as ‘atypical pneumonia’?
mycoplasma pneumoniae
coxiella burnetti
chlamydophila psittaci/pneumoniae
what antibiotics do atypical pneumonia respond to?
tetracycline and macrolides
what are the 2 main ways to get lab confirmation ofmycoplasma, coxiella and chlamydophila?
serology virus detection (PCR on resp swabs/secretions)
what 2 disesaes does Coxiella burnetii cause?
pneumonia
pyrexia of unknown origin (Q fever)
Coxiella burnetii is a zoonotic bacteria, what does this mean?
an animal infection orginally
sheep and goats
what is a major complication of Coxiella burnetii?
culture negative endocarditis
Chlamydophila psittaci is a zoonotic bacteria, what animal is it caught from?
pet birds
parrots, budgies, cockatiels
what does Chlamydophila psittaci cause?
Psittacosis
what does psittacosis usually present as?
pneumonia
how does bronchiolitis usually present?
1st/2nd year of life fever coryza cough wheeze severe: (grunting decreased PaO2 intercostal/sternal indrawing)
what are the 2 major severe cimplications of bronchiolitis?
respiratroy failure
cardiac failure
what are >90% of bronchiolitis cases caused by?
respiratroy syncytial virus
how is RSV confirmed?
PCR on throat/pernasal swab
what is the treatment for RSV?
supportive therapy
what is the one treatment for RSV which was made but was shown not to reduce mortality and so is not widely used?
monoclonal antibody (passive immunisation)
what is the second most common cause for bronchiolitis?
metapneumovirus
how is metapneumovirus confirmed?
PCR on throat/nasopharyngeal swab
what is chlamydia trachomatis?
an STI which can cause infantile pneumonia
how is chlamydia trachomatis diagnosed?
PCR on urine of mother or pernasal/throat swabs of child
how is chlamydophila pneumoniae spread?
person to person
what does chlamydophila pneumoniae cause?
mild respiratory infection
what are 4 important infections of the trachea and bronchi?
acute epiglottitis
acute exacerbations of COPD
cystic fibrosis
pertussis (whooping cough)
what causes acute epiglottitis in children aged 2-7 years old?
haemophilus influenzae
why can’t you do a normal mouth inspection if you suspect epiglottitis?
because if you push the tongue down the epiglottis will move to the top to cover the airways. if the epiglottis is inflamed it might stick to the top and not come down causing respiratory obstruction
what is a test that identifies H. influenzae?
‘X and V’ test
H. influenzae needs both factors X and V to grow
where is the habitat of Haemophilus influenzae as part of the normal flora?
upper respiratory tract
why do you culture Haemophilus influenzae on chocolate agar instead of blood agar?
chocolate agar makes nutrients more readily accessible
what is the treatment for acute epiglottitis?
ITU and ceftriaxone (a 3rd generation cephlasporin)
why is acute epiglottits relatively rare now?
most children get a HIB vaccination
what are the clinical signs of an infective exacerbation of COPD?
sputum gets worse and changes from clear to green (purulent)
what are the 3 most common bacterial organisms associated with an acute exacerbation of COPD?
haemophilus influenzae
streptococcus pneumoniae
moraxella catarrhalis
(all present in normal upper respiratory tract flora, but in COPD colonise lower airways- pathological)
when do you give antibioitcs for an acute exacerbation of COPD?
if sputum is purulent
or signs of consolidation on CXR
or signs of pneumonia
what is the 1st line treatment of an infective exacerbation of COPD?
amoxicillin 500mg
3x per day (5 days)
what is the 2nd line treatment of an infective exacerbation of COPD?
doxycycline 200mg (day 1) 100mg (day 2-5)
what is Cystic Fibrosis?
an inherited defect which leads to abnormally viscid mucus which blocks tubular structures in many different organs including lungs)
in young CF patients what is the most likely bacteria to be causing infection?
staph aureus
haemophilus influenzae
in older CF patients, what are the extermely resistant organisms that can cause infection?
pseudomonas aeruginosa
burkholderia cepacia
what oral antibiotic covers pseudomonas aeruginosa?
ciprofloxacin
what IV antibiotics cover pseudomonas aeruginosa?
gentamycin
tayzocin
what is the organism that causes whooping cough?
bordetella pertussis
how would you describe the timing of coughing in whooping cugh?
paroxysmal coughing
repeated violent exhalations with sever inspiratory whoop
what treatment do you use for borderella pertussis? (whooping cough)
erythromycin
what is the clinical features of a patient with CAP?
cough
sputum production
dyspnoea
fever
what is the most common cause of CAP?
Strep pneumoniae
What are the main causes of CAP?
strep pneumonia
atypicals/viruses
staph aureus
haemophilus influenzae
when does staph aureus usually cause CAP?
as a secondary bacterial pneumonia after the flu
describe Strep pneumoniae?
gram positive cocci in pairs/short chains, alpha haemolytic
why are atypicals not sensitive to penicillins?
because they have a strange cell wall (penicillin usually inhibits cell wall)
if the pnemonia is mild what is the likely causative organism?
strep pneumoniae
if the CAP is mild (CURB65 0 or 1) what is the treatment? (if oral route available)
amoxicillin 1g TDS PO (5 days)
penicillin allergic:
doxycycline 200mg PO (day 1), 100mg (day 2-5)
if the CAP is mild (CURB65 0 or 1) what is the treatment? (oral route unavailable)
amoxicillin 1g TDS IV (5 days)
penicillin allergic:
clarithromycin 500mg BD IV (5 days)
if the CAP is moderate (CURB65 2) what is the treatment?
amoxicillin 1g TDS IV/oral (5 days)
penicillin allergic:
doxycycline 200mg PO (day 1), 100mg PO (day2-4)
if penicillin allergic and IV required:
clarithromycin 500mg BD IV (5 days)
if the CAP is severe (CURB65 3+) what is the treatment?
Co-amoxiclav 1.2g TDS IV (7 days) PLUS clarithromycin 500mg BD IV (7 days) or doxycycline 100mg BD PO (7 days)
if penicillin allergic:
Levofloxacin 500mg BD IV (7 days, monotherapy)
what are 5 predisposing factors to hospital acquired pneumonia?
intubation ICU antibiotics surgery immunsuppression
what are the clinical features of legionella pneumophila?
flu-like illness which may progress to severe pneumonia
mental confusion
acute renal failure
GI symptoms
what is legionella pneumophila associated with?
travel
water
how do you diagnose legionella?
legionella urinary antigen
serology
PCR test on sputum
what is the tereatment for legionella?
erythromycin/clarithromycin
fluroroquinolones eg levofloxacin
(legionella is a atypical so penicillin cant be used)
what type of pneumonia do patients with AIDS get?
pneumocystis jiroveci
PCP
how do you diagnose pneumocystis jiroveci?
bronchioalvelar lavage (BAL) induced sputum direct immunofluorescence (antigen detection)
what is the treatment for pneumocystis jiroveci?
co-trimoxazole
how long does it take for mycobacterium tuberculosis to be grown on culture?
up to 3 months
how do you test for mycobacteria?
positive test to acid and alcohol fast bacili
TB PCR
what is the con about acid and alcohol dast bacili testing?
doesnt give an indication of species or antibiotic sensitivity
what is good about PCR for TB?
provides information on species and sensitivity
what are the pros and cons about culturing TB?
provides best information on antibiotic sensitivity
but very slow
when taking a sputum culture why do you want as little saliva as possible?
saliva will have normal flora, you want to isolate causal pathogen as much as possible
