infectious disease Flashcards
examples of infectious disease
- yellow fever
- MERS
- ebola virus
- monkey pox
- HFMD
- dengue
- avian influenza (bird flu)
- AIDS/HIV
- zika
- influenza
- tuberculosis
- gastroentritis
- COVID19
routes of transmission
- air
- physical contact
- food
- sexual contact
- objects
factors associated with high rates of antimicrobial resistance
- pressure on antibiotic use
- severity of illness
- numerous of invasive devices
- length of hospital stay
- immunosuppression
- malnutrition
- ease of cross transmission of antimicrobial resistant pathogens
areas at risk of infection
- common waiting areas
- procedure holding areas
- examination rooms
- procedure units
measures to minimise infection risk
- hand hygiene
- use of PPE
- dept protocol
- disinfect all equipment between cases
- schedule infected patients at end of cases
main imaging investigation required for patients carrying or suspected of having a lung infection
- chest radiography
- CT imaging
what can pneumonia be classified into
- community acquired pneumonia (CAP)
- hospital acquired pneumonia (HAP)
- ventilator-associated pneumonia (VAP)
- healthcare associated pneumonia (HCAP)
how does chest radiograph with pneumonia look like
- patchy shadowing
- lobar density
- absent/ ill-defind heart borders and hemidiaphragm
- air bronchogram
why is CT strongly recommended for chest imaging
- very sensitive to detecting early disease
- assessing the nature and extent of lesions
- discovering subtle changes that are often not visible on chest radiographs
factors used to describe imaging features of lesions
- distribution
- quantity
- shape
- pattern
- density
- concomitant signs
what is pneumothorax
visceral pleural line is visualised, paralleling the contour of the chest wall
what is atelectasis
- increased density of atelactic portion of the lung and displaced of thorax structures
role of CT in pulmonary infections
- lack of specificity in standard radiography alone especially in immunocompromised patients
- ability to confirm any associated abnormalities such as lymphadenopathy, pleural effusion and/or empyema and any cavities
- assist clinicians to make treatment decisions, especially in emergency and immunocompromised patients
predisposed vulnerable population groups to MSK infections
- elderly and patients with comorbidities such as diabetes mellitus
- end-stage renal failure and immunosuppressed states
plain radiography of msk infection assesses
- osseous alignment and mineralisation
- joint spaces
- soft tissue
- pertinent implants/ FB
osseous findings can be characterised as
- periosteal reaction
- erosions
- osteolytic or osteoblastic lesions
- fractures
role of CT in msk infections
provides
- superior cross sectional and anatomical eval of bone
- particularly of cortical and trabecular anatomy with
- provision for multiplanar volumetric reconstructions
defines
- osseous erosions and destruction
- soft tissue gas inflammation and fluid collections which may not be detectable on radiographs
advantages of using US for msk infections
- provides good soft tissue contrast and spatial resolution
- reliably distinguishing solid tissue and fluid collections
- can screen for a joint effusion which is an early sign of an infected joint
- non-ionising radiation, suited for paeds
limitations of US for msk infections
- highly operator dependent which directly dictates the propensity for false-neg and false-pos findings
- has limited to no capacity to assess deep-seated or intra-osseous pathologies
why is mri the preferred imaging modality in most msk infections
- safe and non-ioninsing imaging modality
- MPI
- able to image edema and detect pathological processes
limitations of mri in msk infection
- expensive, long scanning times and limited availability
- contra-indications such as presence of metallic implants/ cardiac pacemakers
- patient factors: size, claustrophobic
role of nuclear med in msk infection
- locate multifocal or occult infections particularly the osseous rather than soft tissue infections
spine infection classification
- spondylodiscitis
- epidural abscess
- facet joint arthropathy
radiologic imaging on spine infections
- pyogenic
- non-pyogenic
- post procedural infections
what is spondylodiscitis
- infection of the vertebral body or disc and may also involve epidural space, posterior elements, and paraspinal soft tissues
classic findings seen on radiographs for spondylodiscitis
- reduced intervertebral disc height
- endplate erosions
- vertebral osteopenia
- paraspinal soft tissue density
symptoms of abdominal infections
- acute, diffuse or focal abdominal pain
- fever and chills, vomiting, altered bowel transit and general malaise
common cause for abdominal pain or sepsis
- appendicitis, enteritis, iletis, colitis, diverticulitis
- urinary pathologies are pyelonephritis and perinephric abscess
- biliary-pancreatic pathologies –> hepatitis, cholecystitis, cholangitis, liver abscess
advantages of US in abdominal infection
- no radiation exposure
- relatively low cost
- readily available
disadvantages of US in abdominal infections
operator limitations
technical limitations
- adipose tissue thickness
- mobility
- cooperation
- bloating
- intense pain (affect adequate compression)
role of CT in abdominal infections
- speed –> avoids or drastically reduces patient motion artifact
- high definition images with multiplanar reconstructions
- completely independent of patient constitution and diagnosis is independent of operator
how does DWI help in diagnosis of abdominal infections
- differentiate between benign and malignant lesions, and between fluid collection and abscess
- can highlight both oncological and non-oncological lesions
appendicitis findings in US
- alteration of density or echogenicity of pericolonic fat
- presence of a coprolite obstructing the lumen at the level of the appendiceal origin
- non compressible lumen of appendix
pyogenic can be categorised into
- micro or macro abcesses
- single or multiple
imaging features of pyelonephritis and perinephric abscess on mri
- edema, hemorrhage, congestion of the parenchyma, abscesses and perirenal collections can be observed
- inflammatory lesions and collections are hypointense on T1W and hyperintense on T2W
- wedge-like hypovascular lesions with a focal or diffuse stretch-mark pattern
- gadolinium helps to better visualise lesions
