Toxaemic and Respiratory Tract Infections Flashcards
Clostridium
- Toxaemic or respiratory tract infection?
- features
- 3 groups
*Only genus for toxaemic infection
-large, gram positive rods
-spore formers
-toxin producers (usually there to enable the survival of bacteria at the expense of the host)
-Anaerobic (can survive deep in human systems)
3 groups;
1. Neurotoxic
2. Enterotoxic
3. Histotoxic
Neurotoxic
- features of toxin
- 2 pathogenic bacteria that produce neurotoxins
- Very powerful toxins but not infectious
- are a byproduct of bacteria
- Cannot penetrate healthy tissue (only have a local effect)
2 very pathogenic bacteria that produce neurotoxins;
Cl. tetani (Tetanus)
Cl, botulinum (Botulism)
Cl. tetani; Tetanus
- process of germination and effect
- 2 toxins that are produced - what they do
-type of vaccine available (what it is)
-Spores in soil; germinate in wound - proliferate & toxins released
2 toxins released;
-Tetanospasmin: neurotoxin (stops neurotransmitters being released into synaptic cleft which causes spasms, paralysis and respiratory failure)
-Tetanolysin: cytotoxin (may lyse cells)
Toxoid vaccine for humans: “attenuated/inactivated toxins” that allows body to make antibodies against it (form of active immunity - we have to make antibodies [passive immunity = antibodies given to person])
Cl. Botulinum; Botulism
- how absorbed
- what it does
- no. of toxin types
- what toxin is commonly used for nowadays
- spores widespread
- ingest toxin, released from autolysing bacteria
- is absorbed into blood
- also has neuromuscular block -> FLACCID (sagging) PARALYSIS
- works by blocking acetylcholine released by neuron and weakens the muscle (lots of autoimmune diseases also do this) - 6 + toxin types
- Toxin used in Botox
Enterotoxic bacteria -> Cl. perfringens
- how biotypes are typed
- what they do
- features of Cl. perfringens
- 5 biotypes based on toxins
- protein fermenting
- Cl. perfringens has type A only (not a typical enterotoxic biotype)
- Gas gangrene (large blisters with tissue destruction generating gas
- Human food poisoning (from spore coat)
Other Enterotoxic bacteria
Cl. difficile
- features
- antibiotic status
- where found often (very important medically)
- what it causes
Cl. difficile
- Difficult to grow (festidious)
- Antibiotic associated
- causes overgrowth; cytotoxins; mucosal plaques: gneralised toxaemia that can be fatal
- Multiple drug resistant clones now epidemic in US and Europe (kills many hospitalised and elderly)
- nosocomal (can be picked up in hospitals)
Histotoxic
- what they typically follow (events)
- range of effects
- e.g. of risky activities
- several e.g. of bacteria
- Follow wounds/trauma/drug injections
- ranges from local cellulitis to fatal toxaemia (if becomes blood bourne)
e. g. of risky activities; surgical implants, i.v. drug use
e.g. of bacteria; Clostridium novyi, C. sordelli, C. chauvoei, C. septicum, C. perfingens A (different to Enterotoxic type)
Respiratory Infections - features, brief intro
- all are gram negative, coccobacilli/cocci (stumpy rods)
- whole range of genera
- are commensals and opportunists
- stress often causes disease
Haemophilus
- features
- Very important and characteristic feature!
- iron lovers
- Prefer CO2 enrichment
- faculative anaerobe
- Chocolate agar growth
- Require Blood factor X (hemin) and or V (nicotinamide adenine dinucleotide)
- will not grow on blood agar plates (blood needs to be broken down)
- can try and grow with staphococci -> causes blood to break down which results in satellite colonies (will grow around helper bacteria)
Pasteurella
- P. multocida
- antigenic types (what based on, how many)
- features
- vaccines used
- what they cause
- P.multocida: antigenic types based on capsular and O antigens in numerous combos
- Rabbits, dogs and cats carry them
- non-motile
- penicillin sensitive
- Bacterin vaccines widely used (inactivated/heat treated whole bacteria vaccine)
- are zoonotic
- bite wounds (from pets) = cellulitis, adenitis, osteomyelitits
- occasionally causes pneumonia/pleurisy
Haemophilus influenzae
- types (which one most invasive)
- what it causes
- effects in young children
Biogroup aegyptius
Haemophilus ducreyi
- several capsular types; type “b” most invasive (important pathogen)
- non-capsular strains also common
- causes localised respiratory and middle ear infections, usually secondary to viral infections
- causes sepsis and bacterial meningitis in young children
Biogroup aegyptius
-conjuctivitis + septicaemia = Brazilian purpuric fever
Haemophilus ducreyi
- “chancroid” = penile ulcers
- Africa/South East Asia
Bordetella
- B. pertussis
- what it causes
- features of infection
- vaccine (& type)
Bordetella pertussis: “whooping cough”
- Local infection, no septicaemia
- transmitted by direct contact or via aerosol droplets or fomites
- adhere to trachea/bronahiolar epithelium using adhesions
- release cytotoxin that stops cilia from beating, mucous builds up = bouts of paroxysmal coughing: tongue out, sucking in air, cyanotic (turn blue)
*is a common cause of death in developing countries (especially in those less than 1 yr old)
-bacterin vaccines (3 antigenic types)
-disease is common when no vaccine is used
B. parapertussis = milder form
Francisella
- features & what it causes
- where it cycles (and how it differs)
- what it causes
- AKA
- are gram negative cocci baccili
- aerobic
- invasive yet fastidious
- F. tularensis causes Tularaemia (zoonosis)
- Cycles in wildlife (USA, Asia, Parts of Europe -> are different subspecies w/ different pathogenic potentials)
- acute septicaemia after tick bites
- can be inhaled (Lawn mower disease)
- Causes: Swollen lymph nodes, granulomas in liver and spleen (local immune inflammatory response - more cells come to enclose it in)
*Biological warfare agent
Moraxella
- features
- M. lacunata
- what it causes and symptoms (how it achieves this)
- Vaccine?
- gram neg. coccibacilli
- commensals on mucosal surfaces
- M. lacunata: conjunctivitis in humans (and guinea pigs -> zoonotic)
- attaches to conjunctiva via pili - releases dermonecrotic protease toxins (which establishes infection)
- conjunctivitis can eventually lead to cornea opaque, photophobia (fear of light) and then blindess (can take wks to recover
- vaccines used but many antigenic types
Moraxella
M. catarrhalis
- What it causes
- resistance? What does it produce?
M. catarrhalis (Branhamella catarrhalis)
- commensal in humans (diplococci)
- causes chest infections (occasionally otitis media (middle ear disease) or sinusitis)
- Produces beta-lactamases (therefore penicillin resistant)
