Infection Flashcards
how is TB commonly shown on an chest X-ray
upper lobe consolidation
what might be seen in a bronchoscopy of someone with tuberculosis
pus occluding the orifice of the upper lobe, tubercles in the lower trachea
what may remain after treatment of tuberculosis
residual cavities and scarring
describe TB in simple terms
infectious disease of the respiratory tract
what organism and how is tuberculosis spread
airborne spread of mycobacterium tuberculosis
can tuberculosis spread to other organs
yes
where does TB usually present in the lungs and why
at the top as inhaled infection
where do systemic infection present in the lungs
at the bottom
in which countries is TN most prevalent
Indian sub continent, SE Asia, Africa and eastern Europe
what is the role of the macrophages towards TB
intercepts it and turns in granuloma within which the bacteria grows
when does a dormant TB colony become active
when the granuloma breaks open
what percentage of people who are exposed to TB remain well
90%
does infection guarantee immediate disease
- no 10% with lifetime risk, half primary TB, half reactivation of latent disease
what is the reservoir of TB in nature
humans, both pathogen and symbiont
how would you describe the presentation of TB (not symptoms)
subacute (between acute and chronic) disease of gradual onset
what are the general symptoms of TB
weight loss, malaise (weakness or discomfort), night sweats
what are the respiratory symptoms of TB
cough, haemoptysis, breathlessness, upper zone crackles,
what are the symptoms of meningeal TB
headache, drowsy, fits
where does meningeal TB present
in the cerebrospinal fluid
what are the symptoms of spinal TB and why
pain, deformity, paraplegia- infection starts in disc, spreads to adjacent vertebrae with subsequent anterior collapse of that spinal segment
where does gastrointestinal TB present
in the cecum- intraperitoneal pouch considered to be the start of the large intestine
what are the symptoms of gastrointestinal TB
bowl obstruction, pain, perforation, peritonitis
what does TB in the lymph nodes present as
Lymphadenopathy- swelling of the lymph nodes
what is a cold abscess in TB
a collection of dormant TB- lacks inflammation of infection
what must you be cautious of in the elderly
a solitary arthritic joint, might be TB, never inject steroids into it
what are the more rarer presentation of TB (4)
pericardial (tamponade- fluid in the pericardium), renal (failure), septic arthritis (cold monoarthritis of large joints), adrenal (hypoadrenalism)
what are the tests for TB
ZN stain, AAFB, auramine, PCR, radiology
describe a ZN stain
removes all bacteria but mycobacteria due to high wax content of cell wall and acid + alcohol of stain. Blue counter stain then colours them pink. infectious= smear positive. Takes long- sputum cultured for 12 weeks
what does ‘smear positive, smear negative’ mean
infected but not infectious due to low numbers of bacterium
how long does PCR takes and what does it reveal
2 hours, tells you if smear positive and whether its resistant to rifampicin
why might not infected people get a positive result from a PCR test
due to the lasting presence of the disease after treatment
describe the granulomas
multinucleate giant cell
what are the other histological features of TB
caseating necrosis, (sometimes visible) mycobacteria,
what has similar histological features to TB but lacks caseating necrosis and mycobacteria
sarcoidosis
describe the features seen in radiology of TB
upper lobe predominance, cavity formation, tissue destruction, scarring and shrinkage, heals with calcification
what causes miliary TB
massive seeding of mycobacteria through the bloodstream
where does TB in blood present in the chest
everywhere
what antibiotics are used in the first 2 months of treatment for TB
rifampicin, isoniazid, pyrazinamide, ethambutol
what antibiotics are used in the last 4 months of treatment for TB
rifampicin, isoniazid
when and why is directly observed therapy necessary
when not sure if patient taking medication, as have responsibility to protect public health.
what is a way of checking whether a patient is taking their medication
their urine goes pink/orange when taking rifampicin
why cant colourblind patients take ethambutol
as can cause optic neuritis- inflammation that damages optic nerve
what other side affects can rifampicin have
breakdown steroid molecules (hormonal contraception) and opiate analgesics
describe the presence of bacilli during treatment
rapid fall over first two weeks, some non dividing may remain
resistance to which drugs is most common for a single agent
isoniazid
what does MDR stand for and give two common examples
multidrug resistance
rifampicin, isoniazid
what is XDR and give two examples
extensive drug resistance
MDR + quinolone and injectable
TB is often the presenting disease of what condition
HIV
what does XDR mean
increased morbidity
describe latent TB
dormant, balance between organism and immune system
what symptoms are associated with latent TB
none
what culture results will a person with dormant TB receive
TB
how prevalent in latent TB
1/3 to 1/4 of worlds population
what test shows exposure to TB
BCG vaccine- reaction if exposed
what will an X-ray show for latent TB
no evidence
what are the tests for previous exposure to TB
interferon gamma release assay (blood test), Mantoux (tuberculin) (skin test) (detects previous exposure to TB and BCG as well)
how does the BCG vaccine affect TB testing
results in a positive skin test
describe the tuberculin skin test
intradermal injection, return 48 hours later to see if theres a reaction
what can the skin test not distinguish between
latent, cured. active or BCG
describe IGRA tests
performed on blood samples, if exposed body produces interferons (gamma specific to antigen), doesnt react with BCG
when will TST not work
in immunocompromised patients
which test is better. quicker and gives less false positives and negatives
IGRA
how is latent TNF treated
either left or treated with 6 months of isoniazid or 3 months of rifampicin + isoniazid
what are both drugs used to treat latent TB associated with
disturbance of liver function especially in women
what does anti TNF treatment aim to achieve
Rheumatoid arthritis associated with latent TB. Anti-TNF therapy strongly associated with latent TB activation in patients with RA. Anti-TNF aims to avoid complications such as RA, crohns, Psoriasis
how is the reactivation of TB because of anti-TNF drugs clinically presented
a typical
how is TB prevented
contact tracing, screening of high risk subgroups, isolation of infectious cases, BCG immunisation, social measures (housing, nutrition),
describe the BCG vaccine
attenuated strain of mycobacterium bovis, intradermal injection
why does HIV medicine pose a risk for TB
as steroids and immunosuppressants can reactivate latent TB
what is empyema
collection of pus in the pleural cavity
what are some risk factors for pleural infections
diabetes mellitus, immunosuppressants (including corticosteroids), gastro-oesphageal reflux, alcohol misuse, intravenous drug abuse.
what is a pleural effusion
build up of fluid in the pleural space
what are the three types of pleural effusion
simple and complicated parapneumonic, empyema
how do you distinguish between the three types of pleural effusion
acidic pH= simple
cloudy, pos G stain, low glucose, septations, loculations, pH >7.2= complicated
clear puss= empyema
how is empyema treated
aggressively cleaned out + antibiotics
what are the two types of pneumonia
community and hospital acquired
how is a large effusion treated
chest drainage
can v small effusions be left untapped
yes
how is an effusion treated
drainage when necessary, antibiotics,
what antibiotic cannot treat hospital acquired pneumonia/ empyema and why
gentomiosin as cant get into pleural space
what antibiotics used for empyema cover staff
vancomycin
describe the antibiotic treatment for an effusion
two weeks IV, 6 weeks comoxiclav
what do fibrinolytics do
break down clots + structures
what do DNAse do
with firbinolytics can break down clots
are pleural infections common
no
what are the risk factors for developing chronic pulmonary
abnormal host response (immunodeficiency/suppression), abnormal innate host defence (mucosa, cillia, secretions), repeated insult (aspiration, indwelling material)
what are 4 types of immunodeficiency
immunoglobulin deficiency (IgA deficiency, CVID), hypo-splenism, immune paresis (cancer), HIV
what can damage bronchial mucosa
smoking, recent pneumonia, malignancy
what can make cilia abnormal
kartenager’s and youngs syndrome
what can affect secretions
CF, channelopathies
what other than aspiration can cause repeated insult
NG tube, chest drain, inhaled foreign body
what can cause aspiration
NG feeding, poor swallow, pharyngeal pouch, vomiting
what are 5 forms of chronic infection
intrapulmonary abscess, empyema, chronic bronchial sepsis, bronchiectasis, CF
describe the presentation of a intrapulmonary abscess
indolent- causing little or no pain
what symptoms does a intrapulmonary abscess cause
weight loss, lethergy, tiredness, weakness, cough +/- sputum
what does an intrapulmonary abscess often follow
an illness e.g pneumonic infection, viral, foreign body
describe the steps that leads to an abscess forming from flu
flu-> pneumonia-> cavitating pneumonia-> abscess
what is hypogammaglobulinaemia
immune disorder
what can a septic emboli cause
right sided endocarditis, septicaemia
in what group of people are septic embolis common
IVDU
what is empyema
pus in the pleural space
what intervension does a complicated parapneumonic effusion require
chest tube drainage
how is an empyema differentiated from a effusion
empyema has frank pus
how is empyema differentiated from an abscess clinically
CT scan
what do you look for in a CXR when diagnosis a empyema
D sign
what are treatments for empyema
Iv (broad spectrum amoxicillin and metronidazole) and oral antibodies
what does detection of complicated pleural effusion require
sampling of the effusion
what drain types are preferred initially
small bore seldinger
what is bronchiectasis
localised irreversible dilation of the bronchial tree
describe the bronchi when affected with bronchiectasis
dilated, inflamed and easily collapsible
what are the pathological results of dilated and inflames airways
airflow obstruction, impaired clearance of secretions
how is bronchiectasis clinically presented
recurrent infections with no/short lived response to antibiotics and persistent sputum production, chest pain
what has all the hallmarks of bronchiectasis except the CXR
chronic bronchial sepsis
how is chronic bronchial sepsis confirmed
positive sputum results
who does chronic bronchial sepsis usually affect
younger women working in childcare- or older with COPD/airway disease
what are the sinuses a reservoir for
infection
how is bronchiectasis treated
smoking cessation, flu/pneumococcal vaccine, reactive antibiotics
when colonised with persistent bacteria what treatments should be used
prophylactic antibiotics, nebulised gentamicin and colomycin, alternating oral antibiotics
what has been shown to reduce exacerbation rate in bronchiectasis (anti-inflammatory)
macrolide antibiotics
what is the prognosis of bronchiectasis
recurrent infection, abscesses and infection, colonisation
what is a congenital cause of bronchiectasis
cystic fibrosis
what is the mortality from abscess
10%
what is the mortality from empyema
20%
what drugs cause immunosuppression
steroids
what is SPAD
inability to develop antibodies against monosaccharide sugars
what is hypo-splenism
when spleen is taken out, susceptible to streptococci
how does myeloma cause immunodeficiency
produces too much of one immunoglobulin that wipes out all other antibodies
how does chemotherapy cause immunosuppression
wipes out neutrophils
what are multiple abscesses a result of
infection in the blood, bacteremia
what is radiological bronchiectasis
bronchus bigger in diameter than accompanying pulmonary artery
what is clinical bronchiectasis
symptoms without radiological features
how can bronchiectasis be determined by an x ray
as position shouldn’t be able to get that far into the lungs, has to be dilated
what is traction bronchiectasis
radiology but no symptoms
what is the pathophysiology of more than 50% of bronchiectasis cases
idiopathic
what is the range of infections that affect the upper respiratory tract (4)
coryza-common cold, pharyngitis- sore throat, sinusitis, epiglottitis
what is the range of infections that affect the lower respiratory tract (below the chords) (4)
acute bronchitis, acute exacerbation of chronic bronchitis, pneumonia, influenza
what is the common cold
acute viral infection of the nasal passages
how does a common cold spread
droplets and fomites (objects that carry infection)
what are 2 complications of a common cold
sinusitis and acute bronchitis
what viruses cause the common cold
adenovirus, rhinovirus, respiratory syncytial virus
what is the main symptom of acute sinusitis
purulent nasal discharge
how is acute sinusitis treated
usually left limiting and resolves within 10 days, if not antibiotics
why is diptheria so dangerous
life threatening due to toxin production
what is diptheria characterised by
pseudo-membrane
what are the symptoms of acute tonsillitis
swollen tonsils, erythematous, dysphagia (difficulty), dysphonia (difficulty speaking)
what is quincy/quinsy
a complication of tonsilitis- tonsilar abscess
what are the symptoms of strep throat
dysphagia and dysphonia
what is strep throat
an infection of the tonsils
who is acute epiglottis most dangerous to and why
children- life threatening due to obstruction
what are the symptoms of acute bronchitis
productive cough, fever (not common), normal chest exam and CXR, may have transient wheeze
what does acute bronchitis precede
common cold ‘cold which goes to the chest’
what is not used to treat acute bronchitis
antibiotics
in what patients is acute bronchitis dangerous
in COPD patients
what is the incubation period
period of time after exposure to a infection to when symptoms start to show
how is epiglottis treated
IV antibiotics and anaesthetic
what are the features of COPD
chronic sputum production, bronchoconstriction, inflammation of the airways
what are the clinical features of an acute exacerbation of COPD
increased sputum production and purulence, more wheezy, breathless
what does an acute exacerbation of COPD usually follow
upper respiratory tract infection
what is found on examination of a patient with an acute exacerbation of COPD
respiratory distress, wheeze, coarse crackles, maybe cyanosed, when advanced- ankle oedema
how is an acute exacerbation of COPD managed in primary care
antibiotics (doxycycline or amoxicillin), bronchodilator inhalers, short course or steroids (in some cases)
when would you refer someone having an acute exacerbation of
if there is evidence of resp failure, patient not coping at home,
how is an acute exacerbation of COPD manged in hospital
(antibiotics, bronchodilator inhalers, short course of steroids) AND; ABGs, CXR to look for other diseases, oxygen if resp failure
what is red hepatisation
when lung tissue is consolidated and resembles liver tissue
what is consolidation
when an area contains liquid rather than gas
what are some symptoms of pneumonia
malaise, anorexia, rigors, myalgia, headache, confusion, cough, pleurisy, haemoptysis, dyspnoea, abdominal pain, diarrhoea
what is pleurisy
inflammation of the pleura
what can a pneumonia follow
an URTI
what are the clinical signs of pneumonia
fevers, rigor, herpes labialis, tachypnoea, crackles, rub, cyanosis, hypotension
why is reactivation of herpes simplex virus common in pneumonia
due to alteration in the immune system
how is a pneumonia investigated (7)
blood culture, serology, ABGs, full blood count, urea, liver function, VXR
what scoring system is used to measure the severity of a pneumonia
CURB 65 C-onfusion U-rea >7 R-espiratory rate > 30 B-lood pressure systolic < 90 or diastolic < 61 65- y/o or older
does COPD increase the mortality of a pneumonia
yes
what increases as CURB65 increases
mortality
what are other severity markers for pneumonia
temperature, cyanosis PaO2, WBC, multi-lobar involvement
what is the pathogen that most commonly causes pneumonia
strep pneumoniae
who can die from chicken pox pneumonia
adult smokers
what pathogen should you think of when a patient keeps birds
chlamydia psitacci
what pathogen causes a peak in pneumonia every 4 years
mycoplasma pneumonia
how is community acquired pneumonia managed
antibiotics (amoxicillin, doxyxcycline), oxygen, fluids, bed rest, no smoking
what are 4 possible complications of pneumonia
resp failure, pleural effusion, empyema, death
what antibiotics does hospital acquired pneumonia require
extended gram negative cover
what antibiotic cover does aspiration pneumonia require
anaerobic cover
what symptoms are common with legionella pneumonia
chest symptoms may be minimal, GI disturbance, confusion
how is pneumonia prevented
influenza and pneumococcal vaccine
in what group of people is a fungal infection most likely
immuno supressed
what are the symptoms of acute sinusitis
frontal sinusitis, retro-abdominal pain, maxillary sinus pain, tooth ache, disharge
how is mycoplasma pneumonia resistant to beta-lactam antibiotics
as it has no cell wall
what does mycoplasma pneumonia causes
protracted paroxysmal cough- cillial dysfunction, H2O2 production which damaged resp membranes
when should IV antibiotics be given to treat pneumonia
oral route not available (NPO). sensitivities, deep seated infections, first dose
when is sputum important
resistant organism suspected, TB or NTM (non tuberculosis mycobacteria) suspected, failure to improve, high risk indivuals
what pathogen commonly causes pneumonia in people with HIV
PCP- pneumocystis pneumonia
what pathogen commonly causes pneumonia in PWID
staph aureus
what pathogen commonly causes pneumonia in homeless/alcoholic people
TB, klebsiella
what pathogen commonly causes pneumonia in the frequently hospitalised
pseudomonas
what pathogen commonly causes pneumonia in a returning traveller
legionella, TB
what pathogen commonly causes pneumonia in people from the indian sub continent
TB (not always)
what pathogen commonly causes pneumonia in eastern europe
MDR TB (XDR TB)
