Infection Flashcards
Candidiasis
- aetiology: define, types, risk factors, stages
- clinical features
- investigations
- management
- prognosis + complication
Candida albicans (dimorphic fungus) lives in low numbers in healty skin, oropharyngeal cavity and GI and GU tracts
Causes diease in :
- immunosuppressed (HIV, diabetes, steroid use)
- Imbalance of local flora ( antibiotic, steroid use)
- Compromised skin
Causes infection in two eays:
1) Local: imbalance in local flora so C albicans overgrows
2) Systemic infection: breach in skin barrier so dirrectly goes into the blood stream
CLINICAL FEATURES
1) Oral thrush : white plaque in oral cavity that when scraped off show inflamed areas, feels cottony in mouth, see fissuring at mouth corners, patient may have been on ICS (beclomethasone in asthma)
2) Oesophageal candidiasis: AIDS, gget odynophagia (pain on swallow)
3) Vulvovaginitis: vaginal yeast infection, cottage cheese, non-offensive dyscharge, get dysuria and dyspareunia (sexual pain)
4) Systemic candidiasis: fever, fatigue, skin rash, neuro deficits
INVESTIGATIONS
Superficial smear of lesion for microscopy- may be positive for Candida hyphae
Vaginal swab not routinely needed if clinical features there
Blood culture, ABG, rotuine bloods if systemic: high lactate,hypoxia, high WBC, high creatinine, high PT APTT
MANAGEMENT
Vaginal candidiasis or immunosuppressed like HIV: Oral fluconazole
Oral candidiasis (2nd line vaginal) : Topic Antifungals: Clotrimazole, miconazole, nystatin
Severe/systemic disease: Oral fluconozole (echinocandin or fluconazole)
COMPLICATIONS
of oral candidiasis:
- oesophageal candidiasis
- disseminated candidiasis (sepsis)
PRONGOSIS
not bad even if recurrent, but aggressive treatment needed to preent recurrent
Herpes Simplex Virus
- aetiology: define, types, risk factors, stages
- clinical features
- investigations
- management
- prognosis + complication
Strains: HSV-1, HSV-2
Transmitted via direct contact with mucosal tissue or secretions of another person
HSV-1: in childhood via saliva. Causes herpes labialis (cold sores/oral herpes), HSV encephalitis
HSV-2: genital contact, Causes genital herpes
Risk Factors:
HIV
Immunosuppressive medication
CLINICAL FEATURES
Primary infection: severe gingivostomatitis (erythema and painful ulcerations on perioral skin and oral mucosa)
- painful genital ulcers with dysuria and pruritis
- tender inguinal lymphadenopathy
- oral ulcer, may have tingling sensation before
- erythema multiforme
Eczema hepeticum: infection of skin by HSV1 or 2. Seen in children with atopic eczema. Is a rapidly progressing painful rash with punched out erosions
Herpes simplex keratitis: painful red eye, photophobia, epiphoria, fluorescein stain shows liniar blanchin epithelial ulcer. (green little sprout looking thing in eye)
INVESTIGATIONS
If lesions present: VIral PCR
If none: viral culture
If suspect genital herpes: NAAT with swab from base of ulcer
MANAGEMENT
First line (gngivistomatic and genital herpes) : oral acicovir
Cold sores or herpes simplex keratitis: topical aciclovir
Symptom relief: IV fluid, barrier cream, pain relief (topical lidocane), antipyretics, antibiotics
Referral to opthalmologist immediately if herpes simplex keratitis
Pregnant woman with third trimester/28 weeks: Oral aciclovir until delivery and C section
Eczema Hepeticum : IV acyclovir
COMPLICATIONS
- oesophagitis
- meningitis
- encephalitis
- hepatitis
- bell’s palsy
PROGNOSIS
genital herpes and oral herpes are chronic viral infections with a highly variable course. Some people may have frequent outbreaks of disease, whereas others will be completely asymptomatic
Hospital Acquired Infections
- aetiology: define, types, risk factors, stages
- clinical features
- investigations
- management
- prognosis + complication
aka nosocomial Infections, are infections that are contracted 48 hours after hospitalisation and that were not present or incubating at the time of admission
risk factors:
- Age >70 years
- Lengthy hospital stays
- Foreign bodies: catheters or mechanical ventilation
- Recent antibiotic use
- Metabolic diseases (esp diabetes)
- Immunosuppression
COMMON CAUSATIVE PATHOENS AND INFECTION TYPES
Surgical site: E.coli, S.aureus
Nosocomial/HAP Pneumonia: S.aureus, p.aeruginosia or ventilator associated pneumonia
Nosocomal UTI: E.coli
Blood stream: S.aureus
GI: C.diff
Catheter related
Main multidrug resistant is: Methicillin-Resistant Staphylococcus Aureus (MRSA)
Treatment:
HAP pneumonia: co-amoxiclav for 5 days
Human Immunodeficiency Virus
- aetiology: define, types, risk factors, stages
- clinical features
- investigations
- management
- prognosis + complication
Retrovirus that infects and replicates primarily in human CD4+ T cells (lymphocytes) and macrophages, resulting in immunodeficiency
Transmitted via:
- Sexual fluids (majority of cases)
- Blood (IV drugs users sharing contaminated needles or blood transfusions)
- Breast milk
Risk Factors:
- HIV-infected blood transfusion
- IV drug use
- unprotected sexual intercourse
- percutaneous needle prick injury
What is toxoplasmosis
Happens in 50% of cerebral lesions in HIV pations
CLINICAL PRESENTATION
- Constitutional symptoms
- Headache
- Confusion
- Drowsiness
IMAGING
CT showing single or multiple ring-enhanced lesions
MANAGEMENT
Pyrimethamine + sulphadiazine for 6 weeks
Infectious Diarrhoea
- aetiology: define, types, risk factors, stages
- clinical features
- investigations
- management
- prognosis + complication
3 or more loose or watery stools per day or more frequent than normal
- Acute diarrhoea <14 days
- Chronic diarrhoea >14 days
Viral: norovirus, rotavirus, adenovirus
Bacterial: Campylobacter jejuni (poultry, gram - curved rod species best at 42 degrees), E.coli (travellers diarrhoea gram-) , C.diff (antibiotic and PPI associated gram +), Shigella (gram -), salmonella (gram -), bacillus cereus (6 hours then vomiting and diarrhoea)
Parasitic: Giardiasis (can cause lactose intolerance), enterobiasis, amebiasis
RF
- Recent travel (traveller’s diarrhoea)
- Exposure to outbreak
- Recent hospitalisation (c diff)
- Medication use
CLINICAL FEATURES
- Sudden onset watery/fatty/bloody stool
- Fever
- Abdo pain and cramping
- Nausea and vomiting
Norovirus
projective vomiting, incubation 12-24 hours highly infective
Salmonella
spread through eggs, poultry, contaminated food. Typhoid fever symptoms: fever, abdominal pain, non-bloody, yellow-green ‘pea soup’ diarrhoea, rose spots over abdomen
Campylobacter jejuni:
raw meat, incubation of 1-6 days, have prodromal headache and malaise, bloody diarrhoea, about pain mimics appendicitis
s.aureus
1-6 hours after exposure, profuse vomiting (ild diarrhoea)
bacillus cereus
spread through rice and pasta
entamobea histolytica
spread through contaminated water
giardisis
after ongoing diarrhoea and recent travel get abdominal pain, bloating/flatulence (lactose intolerance development), steatorrhoea, lethargy
INVESTIGATIONS
Bacterial infection - stool culture
Viral- PCR test
U&E and CRP and ESR
MANAGEMENT
if no systemic signs:
- Bed rest
- Fluids
- Electrolyte replacement with oral rehydration therapy
Systemic signs:
- Admit
- IV fluids
- Stool culture
For diarrhoea
Anti-diarrhoeal agents e.g. loperamide
ABx
c.diff: oral vancomycin (add IV metronidazole if severe)
campylobacter: clarithromycin
salmonella: ciprofloxacin
Necrotising Fasciitis
- aetiology: define, types, risk factors, stages
- clinical features
- investigations
- management
- prognosis + complication
Life-threatening subcutaneous soft tissue infection that requires a high index of suspicion for diagnosis
Most common site is the perineum (fourniers gangrene: is a risk of SGLT-2 inhibitors in T2DM)
Type 1: polymicrobial infection cause by mixed aerobes and anaerobes (common in post-surgery diabetics)
Type 2: mono microbial infection by streptococcus pyogenes
RF
- skin factors: recent trauma, burns or soft tissue infections
- diabetes mellitus: the most common preexisting medical condition, particularly if the patient is treated with SGLT-2 inhibitors
- intravenous drug use
- immunosuppression
- Varicella zoster infections
CLINICAL FEATURES
- Acute onset
- Anaesthesia or severe pain over site of infection
- Oedema (swelling) and erythema
- Systemic signs of infection:
- Fever
- Palpitations
- Tachycardia
- Tachypnoea
- Hypotension
- Lightheadedness
- Nausea and vomiting
- Delirium and crepitus (advanced cases)
Often presents as: Rapidly worsening cellulitis with pain out of keeping with physical features
INVESTIGATIONS
Surgical exploration to get blood and tissue cultures
MANAGEMENT
Urgent surgical debridement repeated until patient has no necrotic tissue
IV ABx : start as empirical until blood cultures
COMPLICATIONS
- Mortality
- Skin loss
- Scarring
PROGNOSIS
if shock and high-end organ damage 50-70% mortality
Notifiable diseases
- Acute encephalitis
- Acute infectious hepatitis
- Acute meningitis
- Acute poliomyelitis
- Anthrax
- Botulism
- Brucellosis
- Cholera
- COVID-19
- Diphtheria
- Enteric fever (typhoid or paratyphoid fever)
- Food poisoning
- Haemolytic uraemic syndrome (HUS)
- Infectious bloody diarrhoea
- Invasive group A streptococcal disease
- Legionnaires’ disease
- Leprosy
- Malaria
- Measles
- Meningococcal septicaemia
- Monkeypox
- Mumps
- Plague
- Rabies
- Rubella
- Severe Acute Respiratory Syndrome (SARS)
- Scarlet fever
- Smallpox
- Tetanus
- Tuberculosis
- Typhus
- Viral haemorrhagic fever (VHF)
- Whooping cough
- Yellow fever
The ‘Proper Officer’ at the Local Health Protection Team needs to be notified by the medical practitioner
They in turn will notify the Health Protection Agency on a weekly basis
‘immediately on diagnosis of a suspected notifiable disease’ and not to ‘wait for laboratory confirmation of a suspected infection or contamination before notification’
HIV is an exception on the list
Sepsis
- aetiology: define, types, risk factors, stages
- clinical features
- investigations
- management
- prognosis + complication
Life-threatening organ dysfunction caused by a dysregulated host response to an infection
Suspect sepsis based on acute deterioration in patient who has infection
RF:
- Age >65 years
- Immunocompromise
- Recent surgery
- Haemodialysis
- Diabetes
- IV drug use
- Breached skin integrity
CLINICAL FEATURES
- Signs associated with specific infection e.g. cough, dysuria, abdo pain
- NEWS2 ≥5 → indicates sepsis
- High >38 or low <36 temp
- Tachypnoea (20/min)
- Hypotension
- Tachycardia
- Altered mental status
- Low O2 sats
- Oliguria
- Poor CRT
INVESTIGATIONS AND MANAGEMENT
BLUOAF : take 3 give three
Take:
- blood culture (immediately before ABx)
- serum lactate levels ( determines severity, may show metabolic acidosis with raised lactate)
- hourly urine output
Give:
- O2: 94-96% sats to be maintained
- Broad spectrum ABx
- IV Fluid: 500ml crystalloid
also: Vasopressor + inotrope + corticosteroid
COMPLICATIONS
- renal dysfunction
- hypotension
- ARDS
- multiple organ system failure
Varicella Zoster (Human Alpha Herpes Virus)
- aetiology: define, types, risk factors, stages
- clinical features
- investigations
- management
- prognosis + complication
Varicella (chickenpox)
Exclusively human virus- over 80% of people have been infected by the age of 10 years
When susceptible person is exposed to VZV either by direct contact with lesions or through airborne spread from respiratory droplets
Incubation period is 14 days
After primary infection: can become latent in dorsal root ganglia and trigeminal ganglia. Later in lifer it may reactivate and cause shingles. HIV use or immunocompromised (steroid use of chemo) have higher chances.
Groups at highest risk of complications of infection:
- Adults
- Pregnant women
- Immunosuppressed patients
- Neonates
RF
- Exposure to VZV
- Age 1-9 years
- Unimmunised status
- Occupational exposure
CLINICAL FEATURES
- Fever
- Vesicular rash: appears centrally first then spreads to extremities
- Vesicles on mucous membranes e.g. nasopharynx
- Pruritus
- Headache
- Fatigue/malaise
- Sore throat
INVESTIGATIONS
PCR- positive for virus DNA
pregnant women: US to look if foetus affected
MANAGEMENT
supportive: paracetamol
mod-severe: oral aciclovir
severe: IV antiviral therapy
post exposure prophylaxis:varicella-zoster immunoglobulin (VZIG)
give if exposed to chickenpox or varicella zoster, if immunosuppressed, neonates, pregnant women, if have no antibodies to varicella virus
COMPLICATIONS
- Varicella pneumonia
- Encephalitis
- Meningitis
- Hepatitis
- Severe infection in the newborn
What are two issues that are caused by reactivation of Varicella Zoster Virus
1) Ramsay Hunt Syndrome: LMN facial nerve palsy due to reactivation of varicella zoster virus in geniculate ganglion of facial nerve.
Get auricular pain and can get unilateral facial nerve palsy and vesicular rash around ear, some get blisters on anterior 2/3 of tongue
Treat with oral cicilovir and prednisolone
2) Herpes Zoster Opthalmicus: Reactivation of varicella zoster virus in area supplied by ophthalmic division of trigeminal nerve
Vesicular rash around the eye, hutchinson’s sign (rash on tip or side of nose (indicated ocular involvement like anterior uveitis)
urgent opthalmology review, antivirals 7-10 days
Clinical features of shingles
- acute, unilateral, painful blistering rash: erythematous, macular, vesicular rash
- prodromal period of burning pain over affected dermatome for 2-3 days
- infectious until vesicles have crusted over (5-7 days from onset)
paracetamol and NSAIDs, can give antivirals within 72 hours.
Antivirals to reduce chances of post herpetic neuralgia, especially in old people
should avoid contact with immunocompromised and pregnant women whilst infectious
Viral Exanthema
- aetiology: define, types, risk factors, stages
- clinical features
- investigations
- management
- prognosis + complication
Widespread skin rash due to a viral illness
Very common in childhood- especially:
- Chickenpox (varicella)
- Measles
- Rubella
Immunisations with MMR have decreased cases
CLINICAL FEATURES
- spots/blotches on skin with widespread rash usually on trunk
- Fever
- Malaise
- Headache
- Loss of appetite
- Muscular aches and pains
INVESTIGATIONS
- Viral swab
- Blood tests
MANAGEMENT
antipyretics - paracetamol for the fever
moisturising emollients for the itch
Viral Gastroenteritis
- aetiology: define, types, risk factors, stages
- clinical features
- investigations
- management
- prognosis + complication
Acute inflammation of the lining of the stomach and intestines caused by enteropathogenic viruses
Norovirus > sapovirus > rotavirus
Bacterial causes:
- Campylobacter
- E. coli
- Salmonella
RF
- Exposure to contaminated food
- Close contact with infected people
- Poor hygiene
- Extremes of age
- Immunocompromisation
CLINICAL PRESENTATION
- Sudden onset diarrhoea
- Blood or mucus in stool
- Vomiting
- Nausea
- Abdo pain
- Fever and malaise
- Signs of dehydration: dry mucous membrane, skin turgor decrease, cap refill, dec urine output
If norovirus: abrupt onset short lived so 24-48 jours. self limiting but can cause AKI in frail people. Strict hand washing with soap and warm water to prevent spread
INVESTIGATIONS
FBC before starting IV fluid
U&E as can cause dehydration
Stool viral culture
MANAGEMENT
No systemic signs:
bed rest, fluids, electrolyte replacement with oral rehydration
Systemic sign:
Admit + IV fluids + stool culture
C diff: oral vancomycin (add IV metronidazole if severe)
COMPLICATIONS
- Electrolyte abnormalities (metabolic acidosis)
- acute renal failure
- transient lactose intolerance
- Guillain-Barre syndrome
Guillain Barre syndrome
Acute autoimmune demyelinating polyneuropathy affecting the PNS. Occurs after gastroenteritis caused by campylobacter jejuni
CLINICAL PRESENTATION
- back/leg pain in initial stages of illness
- ascending weakness, paraesthesia and pain (i.e. legs are first)
- areflexia (completely absent reflexes)
Can progress and affect respiratory muscles leading to rest failure and death (so must do spirometry test)
INVESTIGATIONS
- CSF (Lumbar Puncture) will show high protein + normal WCC (autoimmune condition, antibodies are proteins, hence increased proteins)
- Nerve conduction studies = decreased motor nerve conduction due to demyelination
- Spirometry test
MANAGEMENT
- IV immunoglobulins (normal antibodies to dilute autoantibodies)
- plasmapheresis (filter antibodies out of plasma)
