theme 1: bacterial pathogens

what is the difference and similarity between staphylococcus aureus, streptococcus pyogenes,streptococcus agalactiae and neisseria meningitidis, neisseria gonorrhoeae?

-both cocci, -positive=staph aureus, strep pyogenes, strep agalactiae (all begin with s=Smile), negative= neisseria meningitidis and neisseria gonorrhoeae (all begin with N= Negative)

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what is the different and similarity between: bacillus anthracis, clostridium difficle, listeria monocytogenes, corynebacterium diphteriae and: salmonella typhi, shigella spp, escherichia coli, proteus spp, yersinia pestis?

-both bacilli, -positive=bacillus anthracis, clostridium difficile, listeria monocytogenes, corynebacterium diptheriae -negative=salmonella typhi, shigella spp, escherichia coli, proteus spp, yersinia pestis

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what class are haemophilus, bordtella, brucella, pasteurella?

gram - coccobacilli (oval shaped)

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what spiral bacteria are there?

helicobacter, campylobacter, borrielia, leptospira, treponema pallidum

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what are the three reasons certain bacteria cause particular infections?

host factors, oppurtunity, bacterial factors

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what is meant by host factors and opportunity?

host=immune system, opportunity= exposure (cannulas ect), normal flora

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what are examples of bacterial factors?

virulence (degree of harmfulness), resistance, environmental survival (some need moisture, some can adhere to certain things)

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what bacteria is the commonest cause of UTIs and bacteraemia and where is it normally found?

e. coli and part of normal bowel flora

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how does e. coli cause a UTI? why is it more common in females?

-can adhere to uroepithelial cells/urinary catheter materials, -colonises the urethral meatus and surrounding area, - triggers host inflammatory response, -short urethra

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why clinically is e.coli a ***?

can develop resistance to antibiotics

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what bacteria is related to skin/soft tissue/surgical site infections and where is it normally found?

s.aureus, in nasal carriage of 30-50% people

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what two properties does s.aureus have that make it good to cause skin infections?

1)able to adhere to damaged skin, 2)makes exoenzymes and toxins->damage tissues and provokes host response (get that phatty pus)

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staphylococcus aureus is a primary pathogen, what is this and how does this differ to staphylococcus epidermidis?

-primary=can induce infection no matter the health status, opportunistic= needs opportunity to cause infection

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what other areas can s.aureus cause infection in (where does it spread)? 6 ways-blood, bone, heart, lung, urinary, cns

1) bacteraemia (bac in blud)/septicaemia (blud poisoning), 2)osteomyelitis (bone infection)/septic arthritis (inflammation of joint due to infection), 3)endocarditis (infection of endocardium, probs valves), 4) pneumonia, 5)UTI, 6) meningitis

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staphylococcus aureus is coagulase positive, how does this differ to staphylococcus epidermidis?

-s.epidermidis is one of 20+ species of coagulase negative staphylococci (can test if coag +/-)

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where is s.epidermidis normally found and what relationship does it have with where its found?

-most people have it on skin, skin commensal (they benefit we just vibe)

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where does s.epidermidis cause infection? give examples

foreign bodies: prosthetic joints/valves, iv catheters

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how does s.epidermidis attach and cause infection/pain to foreign bodies?

-uses glycocalyx (slime) to attach to metal/plastic forms a biofilm, this loosens it causing pain

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what bacteria is group A strep and which is group B strep?

A=Streptococcus pyogenes, B=streptococcus agalactiae

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relating to structure what does staphylo and strepto mean?

-staphylo=bunch of grapes, -strepto=chain

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what is the commonest cause of bacterial sore throat?

streptococcus pyogenes

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what 5 other things can streptococcus pyogenes cause?

-scarlet fever (strawberry tongue), necrotising fasciitis (flesh eating bug), other SSTIs, invasive infections, puerperal sepsis (mum after birth)

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what secondary immunological presentation is streptococcus associated with?

glomerulonephritis

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whats the commonest cause of bacterial pneumonia and meningitis (except in neonates)

streptococcus pneumoniae

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what other common childhood infection can be caused by streptococcus pneumoniae?

e.g. otitis media (middle ear infection)

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if streptococcus pneumoniae was the main cause of bacterial meningitis but not in neonates, whats the main for meningitis (and sepsis) in neonates (baby <3 months)?

streptococcus agalactiae

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how to remember streptococcus agalactiae causes bacterial meningitis and sepsis in neonates?

group B strep- b for babies

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streptococcus milleri complex is a group of closely related species, what is the similarity?

includes 3 species of streptococci that are PUS forming

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yum pus forming streptococcus milleri complex, what condition is this associated with and where do they affect?

abscesses- dental, lung, liver, brain

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what is viridans streptococci a collective name for?

group of alpha haemolytic streptococci (just a characteristic-go green on agar) found in upper resp tract

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if viridans streptococci gets into blood what can it cause?

subacute bacterial endocarditis

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where is streptococcus gallolyticus (strep bovis) normally found?

part of bowel flora- a type of alpha haemolytic strep

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what can happen if streptococcus gallolyticus gets into blood?ie: bacteraemia

associated with colonic malignancies

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what class is listeria monocytogenes, corynebacterium species and propionibacterium acnes?

gram + bacillus

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why do preggers, and also neonates and immunosuppressed patients avoid listeria monocytogenes?

rare but significant cause of sepsis and meningitis in those people

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what food is listeria monocytogenes associated with ?

cheese made from unpasteurised milk (can grow at low temps)

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what area of the body are corynebacterium species commensally found?

skin, upper resp tract

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how does corynebacterium species cause opportunistic infection?

via devices/trauma (need opportunity to cause disease)

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corynebacterium diphtheriae is one of the corynebacterium species. what does it cause, and is it common in uk?

cause of diphtheria, rare due to vaccine

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what is propionibacterium/cutibacterium acnes associated with? duh clues in the name, and 2 other tings?

acne, device associated and post procedural infections

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what are common species included in enterobacteriaceae (coliforms)?

escherichia coli, klebsiella pneumonia, enterobacter cloacae

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what class are enterobacteriaceae (coliforms) and pseudomonas aeruginosa and where are colioform found?

gram negative bacilli, in bowel flora, (multiresistant-pseudomonas aeruginosa)

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e coli commonly causes bacteraemia but where is the source of infection (before it spreads in blood)?

urinary, biliary, intra-abdominal

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often e coli causes nosocomial infections? what are these, and give examples?

-infection originating from hospital, including: line infections, pneumonia, wound infections

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what are toxigenic strains of e coli associated with?

severe diarrhoea and HUS-haemolytic uraemic syndrome

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what type of infections does pseudomonas aeruginosa cause?

respiratory infections, UTIs, soft tissue infections

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which group are more likely to get pseudomonas aeruginosa infections and why?

vulnerable patient, as opportunistic pathogen

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what characteristic colour pigment do pseudomonas aeruginosa make?

green pigment

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what class are neisseria meningitidis and neisseria gonorrhoeae?

gram negative diplococcus

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neisseria meningitidis causes meningitis and smth else, what is this and how does it present?

-meningococca sepsis, purpuric (purpley spots due to small vessel bleeding) non-blanching rash

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is neisseria meningitidis still a issue?

not really as of that phat vaccine bois

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what does neisseria gonorrhoeae cause?

gonorrhoea

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what way could someone get neisseria gonorrhoeae?

sti-secondary to this could get invasive infections (septic arthritis)

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if a mum has neisseria gonorrhoeae, what is the baby at risk of getting during birth?

opthalmia neonatorum (baby conjuctivitis)

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where is haemophilus influenzae normally found?

part of respiratory tract flora

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what does the HIb vaccine prevent?

only type b haemophilus influenzae infections

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what type of infections does haemophilus influenzae cause and give examples

respiratory tract infections, e.g. pneumonia, infective exacerbations of COPD

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what are capsulated types of haemophilus influenzae (e.g. type b) and what are conditions are they associated with?

-these types of bacteria have a polysaccharide capsule, -associated with meningitis and epiglottitis

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what do anaerobes grow in the absence of?

oxygen

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what are common examples of anaerobes?

BCFP-bacteriodes, clostridium (spore forming), fusobacterium, prevotella

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give examples of clostridium species and what they cause? (4)

-c.difficile=antibiotic associated diarrhoae/colitis, -c.perfringens=cause of gas gangrene, -c.tetani=cause tetanus, -c.botulism=cause botulism

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anaerobes can be part of polybacterial infections, what are some examples?

dental infections, lung abscesses, colonic abscess, post-trauma skin/soft tissue infections

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mycobacterium species are referred to as AFBs, what does this stand for?

acid fast bacilli

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Do mycobacterium AFBs stain with the conventional gram stain? explain why they called AFTBs (to do with staining)

-no stain with conventional gram stain (cell wall full of mycolic acid), only stain when washed with an acid wash

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what causes TB?

mycobacterium tuberculosis

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why are aytpical mycobacteria called this and what infections to they cause?

-atypical=as dont stain, 1)resp infections in people with chronic lung disease, 2) opportunistic infection in immuno-compromised patients

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what three species are bacteria without a conventional cell wall?

1)chlamydia 2)mycoplasma 3)legionella pneumophila

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what example of chlamydia is the commonest cause of STI?

C.trachomatis

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what example of mycoplasma is a common cause of respiratory tract infections?

m.pneumoniae

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what does legionella pneumophila cause?

legionnaires disease/legionellosis- lung infection (form of pneumonia)

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what example of spirochaetes causes syphilis?

treponema pallidum

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what 2 other infections does spirochaetes cause?

1)lyme disease 2)leptospirosis

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theme 1: bacterial pathogens

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