Infections JD + MAH Flashcards
Epidemiology?
How often diseases occur in different people and why. Used for prevention strategies.
Agent?
Substance (living/non-living) or force in excess which initiates disease.
Examples of agents?
Biological - bacteria/viruses
Nutrient - carbs
Physical - temperature
Chemical - uric acid
Infection?
Entry + development/multiplication of infectious agent.
Transmission (of infection)
Spread of inf agent through environment (from source)
Host?
Animal/human that affords lodgement for inf agent.
Innate immunity?
immediate response to breach of barrier, causes swelling and redness
Ex of barrier immunity
mucus, skin, acidity
Adaptive immunity?
Delayed response, but specific to pathogens
Barrier immunity?
Prevents pathogens entering body
T cells
kill pathogen infected cells, tell B cells to make antibodies
B cells
Make specific antibodies
Antibodies
Bind to pathogens and make easy to kill
3 major ways for pathogen transmission
- between humans
- via environment (soil/water)
- between humans and animals (vectors)
General transmission factors - abiotic
Wind, water, inhalation of spores, entry through skin
General transmission factors - animal vectors
Mosquitoes, fleas
Human to human transmission - direct contact
pathogen survives best in body through contact within skin, mucous, blood - HIV, ebola, herpes, chickenpox, ringworm, cold sores
Human to human transmission - indirect
path survives harsh environment - through surface or air - influenza, norovirus - objects called fomites - used tissue, handrails
Human to human transmission - droplets
path in droplets - don’t survive long - ebola, bordatella pertussis
Human to human transmission - airborne
aerosolised + stay infective - influenza, TB
Human to human transmission - faecal to oral
excreted from gut - eaten through contaminated food/water (fomite) - cholera, norovirus, shigella, hep a, rotavirus, intestinal worms
Human to human transmission - aerosol
via resp system - breathes, coughs, sneezes into air - another person inhales
Human to human transmission - blood-borne path
unsafe injections. contaminated transfusions - (needles)
Human to human transmission - vertical
mother to child - across placenta or milk
Environmental transmission
Natural reservoir that cause infection - soil + water - clostridium tetani - soil - produces spores
Environmental transmission - water
bacteria e.g or toxins/viruses survive and replicate within water (no host)
Environmental transmission - water - how to prevent? + examples of water-borne infection
sanitisation for safe water supply - cholera + legionnaires
Can env transmission occur from inhaling?
yes - Pontiac fever, legionnaires
Zoonoses?
Transmission from animal to human - ex are avian influenza (birds) + rabies (bite/scratch)
Vector-borne definition?
Part of life cycle in human host - part of cycle must take place in other species known as vector - mosquitoes, flies, ticks and lice
Spectrum of antibiotic activity
- measures how many organisms the antimicrobial targets - antibiotics + antifungals
- narrow - specific
- broad - wide range of organisms - typically target gram+ and gram-
Penicillin V?
oral - narrow spectrum - mild infections (throat/skin)
Penicillin G
unstable in acid - given IV /parenteral - severe infections - pneumonia, meningitis. syphilis
flucloxacillin?
narrow spectrum - gram+
amoxicillin?
broad spectrum
Mechanisms of pathogen-host interaction
1, adherence (pili/fimbriae, adhesins.biofilms)
2. immune evasion (antigenic variation, intracellular survival, inhibition of phagocytosis)
3. tissue damage (toxins, inflammation, host cell death)
Infection pathogenesis
- colonisation (establish residence at site of infection)
- invasion (breach host barriers gaining access to deeper tissues)
- proliferation (path multiply and spread)
- dissemination (spread to other sites/or new hosts)
Pathology ?
(medical) Term describing conditions observed in disease state. Describes abnormal or undesired condition.
Physiology?
(Biological) term describing processes/mechanisms operating within an organism.
Pathophysiology?
Convergence of pathology with physiology. explains functional changes occurring within an individual due to disease or pathologic state. The disordered physiological processes associated with disease or injury. Disruption of the body’s homeostasis; alteration in function, metabolism, organ systems and the mechanisms involved. (easy answer - combo of both - explains how boys normal processes are disrupted during disease leading to illness symptoms)
Aetiology:
- Idiopathic
- Don’t know what’s caused it – want to figure out - Nosocomial (HAI e.g MRSA)
- Healthcare or hospital acquired infections - Iatrogenic
- Caused by a doctor or healthcare professional - Multifactorial
- Pathogens, environment etc
Risk Factor
presence of something increases the likelihood of disease
Pathogenesis
development or evolution of the disease, from initial stimulus to manifestation of disease
Pathogens
agent of disease: virus, bacteria, fungi, environmental, multifactorial
Systems
affects systems i.e respiratory disorders etc complex thus look at pathophysiology of a disease state
- Concept of disease
- Fundamental pathological process
- Systemic pathophysiology
- Pathophysiology of disease
- Concept of disease
- Fundamental pathological process
- Systemic pathophysiology
- Pathophysiology of disease
Clinical course of a disease (biomedical perspective)
- Exposure to pathogen
- Biological onset of disease
(Preclinical phase) - Symptoms appear
(Clinical phase) - Diagnosis
(Clinical phase) - Therapy begun
(Clinical phase) - ‘Outcomes’ (cured; living with the disease; deteriorated; died)
- Diagnosis
(Possible relapse and change in therapy)
Symptoms?
Feeling: Headache, feeling hot, generally unwell
Signs
Measurable: Temperature >38.9, Inflammatory markers, low blood pressure, low platelet count
Syndrome
Diagnosis: Toxic shock syndrome
Inflammatory markers of influenza
- Sudden high temp
- Tiredness and weakness
- A headache
- General aches and pains
- A dry, chesty cough
- Sore throat
- Difficulty sleeping
- Loss of appetite
- Diarrhoea or tummy pain
- Feeling sick and being sick
- Chills
- Runny or blocked nose
- Sneezing
inf markers Escherichia coli (E.coli)?
- Diarrhoea (bloody in half of people)
- Stomach cramps
- Occasionally fever
- Small number go on haemolytic uraemic syndrome (HUS)
- Some people have no symptoms
Staphylococcus aureus
- Painful red lump or bump on skin (boil)
- Hot, red and swollen skin (cellulitis)
- Sores, crusts or blisters (impetigo)
- Sore, red eyelids or eyes (stye or conjunctivitis)
- Staph bacteria can also cause more serious infections, like blood poisoning and toxic shock syndrome. These are much less common than skin infections.
3 Systemic effects of infection?
fever, sepsis, organ dysfunction
Fever?
is the elevation of an individual’s core body temperature above a ‘set-point’ regulated by the body’s thermoregulatory centre in the hypothalamus.
Elevated body temp >38 in response to infection, caused by the release of pyrogens?
- Physiological process brought about by infectious causes or non-infectious causes such as inflammation, malignancy, or autoimmune processes
- Fever is mediated by the pyrogenic activity of prostaglandins, specifically pge2
- Pge2 stimulate endogenous pyrogens such as il-1, il-6, tumour necrosis factor (tnf), and interferon (ifn) to alter the hypothalamic set point
- Endogenous pyrogens also act to trigger an immune and inflammatory response. The immune response includes leukocytosis, T cell activation, B cell proliferation, NK cell killing, and increased white blood cell adhesion
- The inflammatory response includes increased acute phase reactants, increased muscle protein breakdown, and increased synthesis of collagen
Sepsis?
a severe systemic response to infection, characterised by widespread inflammation and organ dysfunction.
What happens during sepsis?
- Infection triggers a dysregulated immune response, leading to a systemic inflammatory state.
- Release of pro-inflammatory cytokines causes widespread endothelial dysfunction, coagulation abnormalities, and organ dysfunction
- Understanding the cascade of events is crucial for early recognition and management of sepsis
- …….. sepsis progressing to septic shock and multi-organ failure results from
1. Circulatory insufficiency characterised by hypovolemia
2. Myocardial depression
3. Increased metabolic demands
4. Vaso regulatory perfusion abnormalities
SIRS?
systemic inflammatory response syndrome describes the inflammatory response, independent of cause, based on a combination of vital signs and blood work.
SIRS includes 2 or more of the following?
- Temp greater than 38C or less than 36C
- HR greater than 90bpm
- Tachypnoea greater than 20 breaths per minute or PaCO2 less than 32mmHg
- WBC count greater than 12,000 per cubic millimetre or fewer than 4000 per cubic millimetre, or greater than 10% immature (band) forms
Severe Sepsis?
- Sepsis associated with organ dysfunction (1 or more), hypo-perfusion abnormality, or sepsis-induced hypotension
- Hypo-perfusion abnormalities may include but are not limited to lactic acidosis, oliguria, or acute change in mental status
Septic shock?
- Sepsis induced hypotension despite adequate fluid resuscitation ?
Organ dysfunction ?
infections can directly impact various organs, leading to impaired function or failure.
What happens during organ dysfunction?
- Organ dysfunction is an integral part of sepsis, and the presence of unexplained organ dysfunction in a patient who is acutely ill should raise suspicion of the possible presence of sepsis and encourage an appropriate diagnostic examination.
- The pathophysiology of organ dysfunction in sepsis is similar for all organs and involves complex haemodynamic and cellular mechanisms.
- First goal in prevention of organ dysfunction in sepsis is to restore and maintain adequate oxygen delivery to cells.
- Single-organ dysfunction in sepsis is rare, and several organs are usually affected; mortality in patients with sepsis correlates with the number of organs that are affected
- Most organ dysfunction in sepsis is reversible
- Current treatment for sepsis aims to limit the development of organ dysfunction by providing rapid control of infection, haemodynamic stabilisation and organ support when possible to ensure recovery of organ function
Pathogenesis of UTI?
- Colonisation
- Pathogen colonises the periureteral area and ascends through the urethra upwards towards the bladder. - Uroepithelium penetration
- Fimbria allow bladder epithelial cell attachment and penetration.
- Following penetration, bacteria continue to replicate and may form biofilms. - Ascension
- Once sufficient bacterial colonisation occurs, bacteria may ascend on the ureter towards the kidney.
- Fimbria may aid in the ascension process.
- Bacterial toxins may also play a role by inhibiting peristalsis (reducing the flow of urine). - Pyelonephritis
- Infection of the renal parenchyma causes an inflammatory response called pyelonephritis.
- While infection of the renal parenchyma is usually the result of bacterial ascension, it can also occur from hematogenous spread. - AKI
- If the inflammatory cascade continues, tubular obstruction and damage occur, leading to interstitial oedema.
- This may lead to interstitial nephritis, causing acute kidney injury.
Chronic renal failure?
look at slide in lecture because its starred?
Pneumonia? signs and symptoms? - look back at lecture - starred slide for development of it?
- Chest pain when breathing or coughing
- Cough, which may produce phlegm
- Fatigue
- Fever, sweating and shaking chills
- Confusion or changes in mental awareness (65+)
Clinical course of a disease: 4 prevention stages?
- Primordial Prevention
- Alter societal structures and thereby underlying determinants - Primary prevention (direct action)
- Alter exposures that lead to disease
(etiological phase – social + environmental determinants, risk + protective factors) - Secondary prevention (early detection)
- Detect and treat pathological process at an earlier stage when treatment can be more effective
(preclinical phase)
(clinical phase) - Tertiary prevention (treatment and rehabilitation)
- Prevent relapses and further deterioration via follow-up care and rehabilitation
(post-clinical phase)
Accurate diagnosis?
understanding mechanisms of infection aids in accurate diagnosis
Effective management?
Knowledge of pathophysiology guides interventions and treatment strategies
Prognostic indicators
recognise systemic effects can provide insights into prognosis and potential complications
Epidemiology?
study of diseases within a population
to look up:
diagnosis, prognosis, morbidity, mortality, incidence, prevalence, endemic, epidemic, pandemic
