Infectious diseases 2 Flashcards
Otitis media:
- Definition
- Causes
- Symptoms (4)
- Signs
- Investigations
- Management
- Complications (5)
Otitis media:
- Definition: middle ear infection common in children as eusch tube shorter + horizontal
- Causes: viral (syncytial, rhino, enterov), bacterial (s pneum, haem influ, moraxella cat)
- Symptoms: otalgia, fever, h loss, ear pulling, irritable, vomiting
- Signs: on otoscopy pull pinna up + back and red bulging tm +/- perforation
- Investigations: MC+S if discharge, CT/MRI if complic
- Management: paracet/ibu, if >48 hours no improvement then 5-7 days amoxicillin. Also prescribe abx if <2 years + bilat infection, eardrum perf, >4 days, <3 months old
- Complications: TM perf (can be wet or dry and central (safer) or peripheral (pars flacida), meningitis, abscess, mastoiditis, facial nerve palsy
TB:
- Definition
- Pathophysiology
- Risk factors (4)
- Symptoms (5)
- Extra-intestinal features (7)
- DD for haemoptysis (3)
- Investigations
- Management
- Complications (1)
TB:
- Definition: infection of mycobacterium tuberculosis
- Pathophysiology: pulmon infection via inhaled droplets where development of subpleural focuses of tubercles (prim gohns focus) and drain into hilar lymph nodes (prim gohn complex). Can spread haematogenous to other sites of body
- Risk factors: contact, overcrowding, third world country, immunosupp
- Symptoms: night sweats, hemoptysis, sputum + cough, dec weight, fever, fatigue, faltering growth
- Extra-intestinal features: erythema nodosum, lymphadenopathy, pericardial effusion (cardiac), addisons (adrenal glands), miliary (disseminated), meningitis (CNS), abdo pain
- DD for haemoptysis: CF/bronchiectasis, vasculitis, coagulopathy
- Investigations: 3x sputum sample stained with ziehl neelsen (an acid ffast stain for acid alc fast bacilli), interferon gamma test (can’t tell if latent/active), mantoux skin test (can’t tell if vaccine/active), bloods (lftss, vit d, hiv), cxr (mediastinal lymphadenopathy, pleural eff, cavit pneumonia), CT chest
-
Management: side room/infection control/public health, 2 months isoniazid (peripheral neuropathy), rifampicin (orange urine, hepatitis), pyrazinamide (hepatitis), ethambutol (optic neuropathy/retrobulbular neuritis), pyridoxine (vit b6 for periph neuropathy) then rifam + isoniz for 4 months
Before/during monitor LFTS/visual acuity
Quantiferon for contact tracing
If latent 3 months rifampicin + isoniazid (or 6 months rifamp)
BCG vaccine at 28 days old and if close contacts - Complications: paradoxical reaction where inc in inflamm as bacteria die causing swelling if spine/pericardial involvement so give steroids also
Otitis externa:
- Definition
- Risk factors (6)
- Causes (3)
- Symptoms (4)
- Signs (2)
- Investigations
- Management
- Complications (3)
Otitis externa:
- Definition: inflammation of external audit meatus
- Risk factors: swimmers, humid environment, immunosupp, excessive scratch, h aids, eczema
- Causes: pseudo aeruginosa, s epidermis, s aures, fungal if recent abx
- Symptoms: otalgia, itchy, discharge, conduct h loss
- Signs: tender pinna, swelling/erythema/discharge ext audit meatus, preauricular lymphadenopathy
- Investigations: swab for mc+s, CT urgent if necrot OE
- Management: dry 7 days, topical abx ear drops, acetic acid
- Complications: malig otitis externa, cellulitis, abscess
Otitis media with effusion:
- Definition
- Symptoms (7)
- Signs
- Investigations
- Management
- Complications (1)
Otitis media with effusion:
- Definition: eusch tube dysfunction where retracted as inc - pressure decreases mobility ossicles + tm reducing hearing (conductive h loss). Common in downs
- Symptoms: assymp, no fever, speech/lang issues, fullness, tinnitus
- Signs: tm retracted, fluid, air bubbles
- Investigations: otoscopy, pure tone audiometry
- Management: watch wait 2/3 months, grommets (tympanostomy tube) can maintain eq pressure however can lead to tympanosclerosis + perf
- Complications: infection otitis media
Malaria:
- Definition
- Causative organisms (5)
- Life cycle
- Symptoms (7)
- Signs (3)
- Investigations
- Management + prevention
- Complications (5)
Malaria:
- Definition: a blood parasite transmitted by night biting anopheles fem mosquitos in asia/ africa
- Causative organisms: plasmodium falciparum (4 weeks incub), vivax, ovale, malarie (6 days - 1 yr)
- Life cycle: infected blood sucked up by mosquitos and makes sporozites which infects another person when bites. Sporozites go to liver and mature into schizocytes which become merozites which burst out of liver cells. These go in and infect rbcs and when reproduce inside cause rbc rupture (hemolytic anaemia). Some infected cells develop into gametocytes which are injested by another mosquito and become sporozites again
-
Symptoms: abrupt onset rigors followed by high fever, malaise, severe headache, myalgia, abdo pain, N+V, diarrhoea, poor feeding
If severe: impaired conscious, renal impairment, acidosis, hypoglycaemia, severe anaemia - Signs: pallor, jaundice, hepatosplenomeg
- Investigations: 3 x thick and thin blood films over 3 days (as 48 hour cycle for parasites to be released from rbcs) showing trophozoites of plasmod falciparum, bloods (fbc (thrombocytopenia, anaemia, leukopenia), u+es, lfts (abnormal), glucose, coag), cxr, CT head
-
Management: IV artesunate (if others chloroquine + primaquine but screen for G6PD def before)
Prevention: bite repellant, chemoprophylaxis (malarone or doxycycline) - Complications: hypoglycemia, renal failure, pul oed, neurolog deterioration, DICs
Immunisations:
- Types: inactive, conjugate, live attenuated
- Schedule
Immunisations:
-
Types:
Inactive: giving killed version of pathogen (polio, flu, hep a, rabies)
Conjugate: parts of organism (pneumococcus, meningococcus, hep b, pertussis, haem influ b, HPV)
Live attenuated: weakened version which can cause infection so don’t give to immunocompromised (MMR, BCG, chickenpox, nasal flu, rotavirus) -
Schedule:
8 weeks: 6 in 1, meningococcal type b, rotavirus oral
12: 6 in 1, pneumococcal, rotavirus
16: 6 in 1, meningococcal b
1 yr: 2 in 1 (haem influ, meningoc), pneumoc, mmr, meningococcal type b
2-8: flu yearly
3 yrs 4 months: 4 in 1 (diphtheria, tetanus, pertussis, polio), mmr
12-13 yrs: hpv
14 yrars: 3 in 1 (tetanus, diphtheria, polio), meningoc
6 in 1: diphtheria, tetanus, pertussis, polio, haem influ b hipb, hep b
HPV gardasil 6, 11 (genital warts) 16, 18 (cervical cancer)
BCG from birth if risk tb
Meningitis:
- Definition
- Pathophysiology
- Causes - neonates, child
- Risk factors (7)
- Symptoms
- Signs (2)
- Complications (4)
- Investigations
- Management
Meningitis:
- Definition: inflammation of meninges due to infection
- Pathophysiology: otitis media —> mastoid process —> blood which damages bv + meninges and multiplies in csf
-
Causes:
Neonates: group b strep, ecoli
Child: haem influ, neisseria meningitidis, strep pneum
If viral: HSV, VZV - Risk factors: csf defects, spinal procedures, splenomegaly, cochlear implants, crowded house, diabetes, endocarditis
-
Symptoms: headache, photophobia, neck stiffness (nuchal rigidity), fever, joint pain, seizures, confused, non blanching rash if meningococcal septicaemia
Baby: floppy/hypotonia, rigid, bulging fontanelle, poor feeding, hypothermia - Signs: these indicate meningeal irritation: kernig sign (ext of knee = resistance), brudzinski (when neck flexed = flexion knees + hips), tachyc, hypot
- Complications: septic shock, DIC, sepsis, cerebral oedema/hydrocephalus, SIADH, hearing loss (swelling of vestibulococchlear nerve), cerebral palsy
-
Investigations: bloods (fbc, crp, u+es, lfts), blood cultures, bloods for meningococcal PCR (quicker results than culture), LP (if <1 month with fever, 1-3 months with fever + unwell, <1 yr with unexplained fever and other features of serious illness) (unless signs inc ICP such as papiloedema/abnormal pupil reflex bc sudden decrease in pressure which cause herniation) and send csf off for bacterial culture, viral pcr, cell count, protein, glucose. LP done prior to abx unless v unwell
LP between L3/4
Bacterial: cloudy, inc protein, inc wcc (neuts), decreased glucose, + gram stain
Virus: clear, normal/inc protein, high wcc (lymphocytes) normal glucose
TB: high protein, decrease glucose, lymphocytes - Management: if presents in GP IM benzylpenicillin, analgesia, dexamethasone for 4 days, if >3 months ceftriaxone/ if <3 months then ceft + amoxicillin (covers listeria contracted during preg), vancomycin if risk penicillin resistant pneumococcal infection, acyclovir if viral, if contact within 7 days before onset single dose ciprofloxacin. Notify public health
Primary immune deficiency syndrome:
- Definition
- Risk factors (1)
- Symptoms (4)
- Red flags
- Investigations
- Complications (5)
- Types: B cell, T cell, combined, complement, neutrophil disorders
Primary immune deficiency syndrome:
- Definition: heterogenous group of disorders due to defects in immune system development/function. They are classified as disorders of adaptive immunity (T/B/combined deficiency) or innate (phagocyte/complement)
- Risk factors: fam hist
- Symptoms: recurrent ear/sinus/pneumonia infections, failure to thrive, poor response to prolonged use of abx, persistent thrust/skin abscesses, chronic diarrhea
-
Red flags to suspect: Serious, Persistent, Unusual (CMV, candida, pneumocystis jiroveci), Recurrent
10 warning signs: >4 ear infections in a year, 2 or > serious sinus infections in 1 year, recurrent deep skin/abscess infections - Investigations: bloods (fbc (neuts? lymphocytes?), lymphocyte subsets, total antibodies (Ig levels?), complements), HIV test, cxr for scarring, sweat test for CF, HRCT for bronchiectasis
- Complications: recurrent infections, autoimmune disorders, damage to organs, slowed growth, increased risk cancer
B cell / antibody deficiency: deficiency in ab = hypogammaglobulinemia
1. Selective IgA def: IgA present in mucous membranes saliva/resp tract/GI secretions. Often assymptomatic, recurrent LRTI + autoimmune conditions
2. Common variable immunodef: deficiency in IgG/A and maybe M. Recurrent resp tract infections, can’t develop immunity to vaccines, RA, non-hodgkins lymphoma. Need Ig infusions
3. X linked agammaglobulinaemia (bruton’s): abnormal B cell development so all Igs low and similar to common variable immunodef. Starts around 6 months when maternal IgG reduces.
T cell disorders:
1. DiGeorge Syndrome: 22q11.2 deletion syndrome affecting third pharyngeal pouch/third brachial cleft development so affects development thymus gland so can’t create functional T cells. Congen HD, abnormal facial, Thymus bad, Cleft palate, Hypoparathy/calc
Severe combined immunodef syndrome SCID: dysfunctioning B/T cells due to x linked recessive mutation in common gamma chain for interleukin receptors on B/T cells hence lymphocytes v low!! They have persistent diarrhea, fail to thrive, opportunistic infections, unwell after live vaccinations (BCG, MMR, flu) and omen syndrome (this is a cause of SCID where T cells attack tissues in fetus leading to alopecia, diarr, lymphadenop, erythroderma, hepatosplen). Ig therapy, avoid live vaccines, HSCT
Complement disorders: complement proteins are involved in opsonisation and chemoattraction of phagocytes to destroy in particular haem influ b, strep pneum, neiss mening. Hence leads to resp, ears, throat infections and also associated with SLE as immune complexes build up and deposit leading to inflammation. Manage via penicillin prophylaxsis and vaccinations against encap organisms
Neutrophil disorders: these phagocyte predom bacteria (and fungi) and act as ag presenting cells
1. chronic granulomatous disease: recurrent abscesses of staph aures, and fungal chest infections. Defects in NADPH oxidase which phagocytes need to kill bacteria/fungi. Lifelong abx/antifungals, IFgamma injections
Peri-orbital cellulitis:
- Definition
- Pathophysiology
- Causes (2)
- Symptoms pre-orbital (2)
- Symptoms post orbital (6)
- Investigations
- Management
- Complications (2)
Peri-orbital cellulitis:
- Definition: infection of periorbital soft tissue common if <10yrs old with bi-modal seasonal variation (late winter/early spring)
-
Pathophysiology: contiguous spread from surrounding periorbital structures such as paranasal sinuses esp ethmoidal. More common in children as thinner and dehiscent bone surface of their lamina papyracea and increased diploic venous supply. Divided into pre-septal (infection anterior to orbital septum which is thin fibrous layer) and post-septal
Normally other sinus involvement: dacrocystitis, dental infections, impetigo - Causes: strep pneumoniae, h influ
- Symptoms pre-septal: eyelid oedema (due to impedance to drainage through ethamoid vessels), erythema upper eyelid. Usually history of acute sinusitis or URTI before
-
Symptoms post-septal: same as above, orbital signs (proptosis, opthalmoplegia, decreased visual acuity, painful dipopia, chemosis, loss red colour vision (sign optic neuropathy)
Chandler classification classifies what type cellulitis - Investigations: vital signs, dentition, rhinoscopy, nose swab MC+S, ophthalmic examination (eye movement, colour vision, visual acuity, pupil response, tonometry, ant segment biomicroscopy, opthalmoscopy), neurological exam, bloods (crp, fbc, u+es, abg, lactate rules out sepsis), CT or orbital contents + sinuses
- Management: if pre-septal >1 yr oral abx but if post hospital admit for iv abx. IV fluids, analgesia. Emergency drainage if optic nerve compromised or intracranial complications (enceph/meningitis, cavernous sinus thrombosis)
- Complications: blindness, intracranial abscess/ other intracranial complications
Viral gastroenteritis:
- Definition
- Causes (3)
- Symptoms (4), those at risk of dehydration, symptoms dehydration, shock symptoms
- Investigations (3)
- Management
- Complications (4)
Viral gastroenteritis:
- Definition: enteric infectious (inflamm of stomach to intestines) most commonly caused by viruses
- Causes: rotavirus (most common in infants via faecal oral route or environment contamination esp in winter. Oral vaccine at 8 + 12 weeks), norovirus (RNA virus most common in all age groups and same route as rotav), adenovirus (esp if <2 years)
-
Symptoms: sudden onset diarrhea, vomiting, abdo pain, mild fever
Those at risk of dehydration: <6 months, >5 stools in 24 hours, >2 vomit in 24 hours, stopped breast feeding
Dehydration symptoms/signs: decreased urine output, change in responsiveness, warm extremities, dry mucus membranes, tachycardia/pnoea
Shock signs: decreased level consciousness, cold extremities, hypotension, prolonged cap time - Investigations: stool sample for MC+S if blood/mucus/ septicaemia/immunocomp, bloods (u+es, glucose, creatinine) if signs hypernat, VBG if shock signs
-
Management: if in hospital isolate, continue to feed/fluids, discourage fruit juices, oral rehydration salt solution - ORS solution 50ml/kg over 4 hours plus maintenance. IV fluids if shock/ dehydration where oral rehydration salts not working. When rehydrated full strength milk straight away and slowly reintroduce solids. Avoid sharing towels and no school until 48 hours after diarrhoea and no swimming 2 weeks
D lasts 5-7 days and V 1-2 days
Maintenance calculation:
0-10 kg - 100ml/kg/day
10-20kg (1st 10 kg above hence 1000ml) + 50ml/kg/day
>20kg (1st 20kg above hence 1500ml) + 20ml/kg/day - Complications: hemolytic uraemic syndrome causing renal failure/hemolytic anaemia, acquired lactose intolerance, toxic megacolon (rotavirus), reactive arthritis (bacterial)
