Key Pathogens Flashcards
(20 cards)
1
Q
Neiserria meningitidis
What’s its
- gram stain
- mechanism of infection
- interaction with host
- how to diagnose
- treatment
- prevention
A
- gram stain : -itive diplococcus
- mechanism of infection: direct contact with respiratory secretion
- interaction with host: colonises meninges of brain and progresses to blood = non blanching rash. Causes severe immune reaction = drastic fall in TPR = septic shock, multi organ failure and death.
- how to diagnose: sudden onset of malaise, the get fever, neck pain, photophobia, nausea, headache, tachycardia and tachypneoa.
- treatment: antibiotics e.g ceftriaxone. Supportive = high flow o2, adrenaline, fluid IV.
- prevention: vaccine
Nb: most common. Cause of meningitis in ages 2-18
2
Q
Streptococcus pneumoniae
Whats its
- gram stain
- mechanism of infection
- interaction with host
- how to diagnose
- treatment
- prevention
A
- gram stain: +itive
- mechanism of infection: direct contact, normal in upper respiratory tract but colonise in lungs
- interaction with host: bacteria in lungs cant be phagocytosed by neutrophils due to thick capsule = pus from netutrophils accumulates and consolidates in lungs = get symptoms.
- how to diagnose: 3 days of dysphasia and malaise, 4-5 days of yellow sputum, tachycardia, mild hypotension
- treatment: supportive = high flow o2 and correct fluid balance, specific = antibiotics
- prevention : Antibiotic prophylaxis
3
Q
Escherichia coli
What’s its
- gram stain
- mechanism of infection
- interaction with host
- how to diagnose
- treatment
- prevention
A
- gram stain: -itive bacilli
- mechanism of infection: ingestion of contaminated food
- interaction with host: colonise GI tract or exit the bowel after surgery = peritonitis
- how to diagnose: nauseous, ingested food 1-8 days before, diarrhoea, vomiting, fever, malaise, stomach cramps, muscle weakness.
- treatment: IV fluids, antibiotics, high flow o2
- prevention: don’t cook with people with gastroenteritis and disinfect food prep areas regularly
Nb: normal site is the bowel
4
Q
Clostridium difficile
- gram stain
- mechanism of infection
- interaction with host
- how to diagnose
- treatment
- prevention
A
- gram stain: +itive bacillus
- mechanism of infection: opportunistic infection when normal bacteria of gut is eliminated by antibiotics.
- interaction with host: exotoxin A causes inflammation that leads to intracellular spaces widening and exotoxin B goes through gaps to kill healthy cells.
- how to diagnose: 2 days of severe diarrhoea, rarely vomiting, abd o discomfort, BP low, tachycardia
- treatment: IV fluids, antibiotics
- prevention: isolation, responsible prescribing, wash hands throughly.
5
Q
Salmonella typhi
- gram stain
- mechanism of infection
- interaction with host
- how to diagnose
- treatment
- prevention
A
- gram stain: -itive rod
- mechanism of infection: faecal oral (contaminated food/water)
- interaction with host: enter GI tract and hits SI where it interacts with peyers patches and adheres, eventually entering blood and causing bacteriaemia.
- how to diagnose: incubation period of 7-14 days so get ill when returning from travels. Increasing intensity of fever, headache, abdominal tenderness, constipation and dry cough.
- treatment: pain relief e.g paracetamol, oral rehydration, ceftriaxone antibiotic
- prevention: food and water hygiene and hang washing.
6
Q
Viridans streptococci
- gram stain
- mechanism of infection
- interaction with host
- how to diagnose
- treatment
- prevention
A
- gram stain: +itive cocci chains
- mechanism of infection: normalin oral cavity, but if breached can cause tooth decay and spread to CVS
- interaction with host: colonise tooth surface where it converts ingested sucrose to lactic acid = lowers pH of enamel and can lead to breakdown. Then, if oral cavity is breached = can enter circulation and can go to heart valves and cause endocarditis.
- how to diagnose: poor dental care, fever and chills for at least 6 weeks, breathlessness, toothache, anorexia, hypotension, peripheral oedema and possible tachycardia.
- treatment: o2 for tachypnea, replace defective valve and penicillin.
- prevention: good dental hygiene
7
Q
Coagulase negative staphylococci
- gram stain
- mechanism of infection
- interaction with host
- how to diagnose
- treatment
- prevention
A
- gram stain: +itive cocci clusters
- mechanism of infection: inoculation onto prosthetic surfaces during surgery
- interaction with host: usual skin flora, can form biofilms on surgical equipment so cant be defeated by immune system = local infection. If biofilms are sheared off = can go into systemic circulation and cause septic shock. Can also cause rejection of prosthetics e.g artificial knees or hip replacements if infiltrates at time of surgery.
- how to diagnose: pain in site of implant, unsteadiness on joint, tenderness, malaise, fever, myalgia.
- treatment: manage symptoms and physiotherapy for limb, surgical removal of prosthetic, antibiotic regime also.
- prevention: silver coated IV lines (antibacterial), sterile surgical environment, antibiotic prophylaxis when anaesthetised.
8
Q
Pseudomonas aeruginosa
- gram stain
- mechanism of infection
- interaction with host
- how to diagnose
- treatment
- prevention
A
- gram stain: -itive bacillus
- mechanism of infection: inhalation of bacteria which begin to colonise the respiratory tract
- interaction with host: opportunistic, enters though URT, colonises in bronchi = bronchopneumonia. Has mucopolysaccharide capsule = are to phagocytosis.
- how to diagnose: symptoms similar to pneumonia, tachycardia pulmonary crackles, dry cough, fever etc.
- treatment: fluid, o2, salbutamol, tobamycin (antibiotic)
- prevention: don’t let cf suffers met, pulmonary physiotheraphy, prophylactic antibiotics
9
Q
Staphylococcus aureus and MRSA (methicillin resistant staphylococcus aureus)
- gram stain
- mechanism of infection
- interaction with host
- how to diagnose
- treatment
- prevention z
A
- gram stain: +itive coccus
- mechanism of infection: invasion (break of mucosa) , inhalation, ingestion. Can be hospital acquired. MRSA spreads skin to skin contact or through objects used by the infected individuals.
- interaction with host: virulence factors e.g DNA ribonuclease breaks down host DNA, coagulase forms a micro clot around bacteria to protect it from phagocytosis.
- how to diagnose: forms in skin lesions of the immunocompromised, must be evidence of a large lesion and then swab it and culture. If sepsis, can expect tachypnea, tachycardia and hypotension.
- treatment: if septic need sepsis 6 and antibiotics as well as draining abscess. MRSA is resistant to beta lactams, some penicillins and cephalosporins. Used flucloxacillin.
- prevention: hand washing, decontamination of cooking surfaces, etc.
Can cause cellulitis and endocarditis.
10
Q
Legionella pneumophilia
- gram stain
- mechanism of infection
- interaction with host
- how to diagnose
- treatment
- prevention
A
- gram stain: -itive rods
- mechanism of infection: aerosolisation of eater and soil infected with bacteria
- interaction with host: undergoes phagocytosis but inhibits formation of phagosome so multiplies within macrophage until it bursts = lower WBC count
- how to diagnose: fever, shortness of breath, productive cough
- treatment: serum lactate measure, high flow o2 and antibiotics.
- prevention: keep water below 20 degrees or above 60 degrees, don’t let water stagnate
11
Q
Norovirus
- DNA/RNA
- mechanism of infection
- interaction with host
- how to diagnose
- treatment
- prevention
A
- DNA/RNA: ssRNA
- mechanism of infection: person to person directly or indirectly from water of contaminated food
- interaction with host: multiplies in small intestine and irritates the lining of the GI tract
- how to diagnose: nausea, vomiting under 2 days after exposure, diarrhoea, dehydration (dry hair, pale, reduced urine output, tired, headache)
- treatment: IV fluids supportive
- prevention: wash hands thoroughly
12
Q
Adenovirus
- DNA/RNA
- mechanism of infection
- interaction with host
- how to diagnose
- treatment
- prevention
A
- DNA/RNA: dsDNA
- mechanism of infection: droplet infection, direct contact, faecal oral transmissions
- interaction with host: enters through respirator route and colonise pharynx and cause URTI, can cause conjunctivitis if gets in eyes, or go down oesophagus and colonise GI tract and cause gastroenteritis
- how to diagnose: coughing and sinus pain, temperature, malaise. Red enslaved pharynx and enlarged tonsils.
- treatment: mild pain relief, increase fluid intake
- prevention: spreads by droplets so avoid those showing symptoms and avoid enclosed spaces
13
Q
Influenza A
- DNA/RNA
- mechanism of infection
- interaction with host
- how to diagnose
- treatment
- prevention
A
- DNA/RNA : non sense ssRNA
- mechanism of infection: droplets
- interaction with host: droplets inhaled, enters cell in upper respiratory tract. Cytokines overreaction is the cause of most symptoms.
- how to diagnose: fever, aches and pains, dry cough, malaise, myalgia
- treatment: pain relief, antipyrexials, antiviral
- prevention:flu vaccine and good hygiene
14
Q
Human immunodeficiency virus
- DNA/RNA
- mechanism of infection
- interaction with host
- how to diagnose
- treatment
- prevention
A
- DNA/RNA: ssRNA
- mechanism of infection: spreads though bodily fluids
- interaction with host: enters blood stream, infects cd4+ T cells, replicates then exits by causing lysis of the T cell. Become immunocompromised = opportunistic illnesses come forward. The main ones are oral Candida albicans (oral thrush), kaposis sarcoma, pneumocytosis pneumonia and TB
- how to diagnose: findings of aids defining illnesses, acute infection is flu like.
- treatment: treat aids defining illnesses, then for aids 2 NRTIs (nucleotide reverse transcriptase inhibitors) and 1 NNRTI (non nucleotide reverse transcriptase inhibitor or 1 protease inhibitor or 1 integrase inhibitor
- prevention: avoid unprotected sex, use PPE when treating patients, avoid contact with other peoples body fluids
15
Q
Hepatitis B
- DNA/RNA
- mechanism of infection
- interaction with host
- how to diagnose
- treatment
- prevention
A
- DNA/RNA : dsDNA
- mechanism of infection: bodily fluids
- interaction with host: enters bloodstream and replicates in hepatocytes causing host damage by inflammation when mine system recognises viral molecules
- how to diagnose: fatigue, abdominal pain, anorexia, nausea, vomiting, hepatomegaly, jaundice (of sclera particularly)
- treatment: supportive for symptoms vaccinate if early enough and antiretroviral drugs in chronic infection.
- prevention: vaccination, avoid bodily fluids, use PPE with patients
16
Q
Hepatitis C
- DNA/RNA
- mechanism of infection
- interaction with host
- how to diagnose
- treatment
- prevention
A
- DNA/RNA: ssRNA
- mechanism of infection: blood to blood contact
- interaction with host: travels to liver and replicates within hepatocytes but doesn’t usually cause symptoms
- how to diagnose: asymptomatic but may be fatigue, nausea, dark urine, anorexia.
- treatment : supportive and antiviral to stop replication and stimulate immune system
- prevention: harm reduction strategies e.g clean needles for IV drug users, PPE when dealing with patients.
17
Q
Varicella zoster(chickenpox)/herpes zoster (shingles!)
- DNA/RNA
- mechanism of infection
- interaction with host
- how to diagnose
- treatment
- prevention
A
- DNA/RNA: dsDNA
- mechanism of infection: inhalation of virons from an infected persons lungs
- interaction with host: normal adaptive immune response followed by lifelong persistence of IgG antibodies, conferring lifelong immunity. Varicella zoster lies dormant in dorsal ganglion of sensory nerves, reactivation leading to shingle.
- how to diagnose: SHINGLES - previous exposure to chickenpox and a rash that corresponds to a single dermatome, some form of immunosupression.
- treatment: pain relief and anti itching cream
- prevention: treat the immunocompromised but other than that not really treatable.
18
Q
Epstein Barr virus
- mechanism of infection
- interaction with host
- how to diagnose
- treatment
- prevention
A
- mechanism of infection: found in saliva, blood and semen so can go either way
- interaction with host: replicates in oropharyngeal epithelium and infects B cells, immobilising them.
- how to diagnose: fatigue, fever, lack of appetite, rash, swollen glands in neck, weakness, lack of appetite. GLANDULAR FEVER
- treatment: supportive treatment and antivirals.
- prevention: don’t share items with someone whose infected and don’t kiss or have sex with someone who is infected.
19
Q
Aspergillus fumigatus
- yeast/mold
- mechanism of infection
- interaction with host
- how to diagnose
- treatment
- prevention
A
- yeast/mold: mold
- mechanism of infection: spores inhaled by immunocompromised = opportunistic
- interaction with host: actively multiply in alveoli/ alveolar epithelium, those who aren’t immunocompromised just clear by alveolar macrophages
- how to diagnose: cough, fatigue, weight loss, tachycardia, wheeze, tachypnea
- treatment: high flow o2, antipyrexials, pain relief, anti fungals.
- prevention: avoid areas when aspergillus spores are abundant
20
Q
Plasmodium falciparum/vivax (malaria)
- mechanism of infection
- interaction with host
- how to diagnose
- treatment
- prevention
A
- mechanism of infection: vector spread by female anopheles mosquito
- interaction with host: enters host from salivary glands of mosquito, enters bloodstream, goes to liber and colonises there before going to invade RBC and use Hb as a nutrient until oncosis of RBC occurs = haemolytic anaemia.
- how to diagnose: splenomegaly, fever, chills and sweats, dry cough, headache, nausea and vomiting.
- treatment: antipyrexials, pain relief, if falciparum is quinine or armitemisin, if vivax or anything else = chloroquine.
- prevention: wear long clothes, antimalarial prophylaxis, asses if patient is willing to travel to area.
