Lecture 24 Flashcards
What are the barriers to microbial colonization?
Intact Skin, Respiratory mucous and cough reflex Gastric acid and peristalsis Tears and blinking Bladder emptying
What are the local and circulating immune responses?
Specific antibodies Cytotoxic Lymphocytes Helper Lymphocytes Macrophages Neutrophils Complement
What occurs in a severe burn?
Loss of barriers to colonisation and heavy microbial colonisation of S.Aureus, S.Pyogenes and Pseudomonas Aeruginosa leading to bacteraemia
What can occur to patients with a urinary catheter?
Heavy colonisation of bladder by bacteria,as a stagnant pool of urine forms around catheter balloon
E.Coli, Proteus Mirabilis, Klebsiella pneumoniae, Pseudomona Aeruginosa
Leads to pyelnephritis
What are 4 ways in which barriers to microbial colonisation can be disrupted excluding burns and catheters?
Intravenous Cannulae Endotracheal tubes Abnormal respiratory mucous Impaired Cough Gastric achlorhydia
What is the usual microrganism that causes disease from intestinal contents?
E.Coli
How much do the chances of developing an infection increase per day when a urinary catheter is used?
5% per day
What are the mechanisms through which innate immunity can be impaired?
Impaired function of neutrophils (rare)
Low Numbers of neutrophils
Reduced or absent complement
How many neutrophils are produced each day? How long do they last? and is their aprox. concentration in the blood?
10^11 Are produced each day
Half Life is between hours to days (very short for cells)
Approximately 1 neutrophil per 500/1000 RBCs or 2-8*10^8/L
What are the two causes of neutrophil deficiencies and what are there consequences?
Rare Congenital deficiencies which typically result in death during infancy
Drug induced deficiency is possible which results in a high risk of infection
What are the possible impairments of neutrophils?
Impaired chemotaxis, phagocytosis and digestion
these are all rare as sufferers don’t tend to live long enough to pass on the genes
What is Chronic granulomatous disease?
When there is a deficiency of superoxide in phagocytic vacuoles
What bacteria will take advantage of a low neutrophil count to cause disease/
S.Aureus
S.Pneumoniae
Salmonella spp
What are the features of deficiencies of complement?
They are very rare (approx 0.1%)
Associated with increased risk of meningococcal
What occurs when there is a deficiency of antibody?
Multiple myeloma (B Cell Cancer) and recurrent bacterial infections of gut and respiratory tracts
What is multiple myeloma?
When there is lots of antibody present but very little useful antibody is present
What microorganisms cause respiratory tract infections in antibody deficiencies?
S.Pneumoniae
Haemophilus influenzae
What causes T lymphocyte deficiency and what is the consequence of this?
Impaired function due to age, drugs and infections
Reduced by HIV infection, drugs
This results in increased susceptibility to intracellular infection
What infections occur most commonly with T helper lymphocyte deficiencies?
Viruses such as varicella zoster, cytomegalovirus, herpes simplex
Intracellular protozoae such as toxoplasma gondii, Pneumocystis carinii
Fungi such as candida albicans
Intracellular bacteria such as mycobacterium tuberculosis
What sites of the body are naturally immunodeficient and what does this result in for infections of these sites?
Cerebrospinal fluid and heart valves, the consequence of this is that the infection gets a head start as it grows quickly before capillaries become leaky enough to allow leukocytes through
What are the infections that typically occur in naturally immunodeficient sites?
Meningitis which has a high 80% mortality without treatment
Endocarditis has 100% mortality without treatment
What is the consequence of a foreign body entering the body?
Host response cannot remove any microorganisms on this foreign material
