Bacterial Pathogens Flashcards
What are the two classification of bacterial pathogens
gram stain and shape
what type of bacteria aren’t classified normally
ones that don’t have a cell wall
what are the 6 classifications of bacterial pathogens
gram + cocci gram + bacilli gram - cocci gram - bacilli gram - coccobacilli spiral bacteria
what are the normal staining chemicals and what is the difference in staining for a thick cell wall and a thin cell wall
iodine and crystal violet
thick cell wall = gram positive and holds the stain
thin cell wall is gram negative and cannot hold the stain
what is the triad of factors for bacterial infection
host factors - devices/immune system
opportunity - exposure/normal flora
bacterial factors - virulence/resistance/environmental factors
how does E/coli cause UTI’s
especially in females
normal bowel flora colonises in the urethral meatus and surrounding area such as lower GIT/bowel
in females - short urethra making easier infection - risk of developing resistance to antibiotics
where is S. areas commonly found and what can it cause
in the nasal cavity of up to 50% of people - can infect damaged skin to provide host response
what are the two classes of gram + cocci
streptococcus
staphylococcus
describe the type of infection of staphylococcus aureus and what is can lead to
Primary - can infect anyone, 30-50% present in nose of people
most common cause of skin/soft tissue infection including at surgical sites
can cause - bacteriamia/septicaemia, septic arthritis, endocarditis, pneumonia, UTI and meningitis
describe the type of infection of staphylococcus epidermis and what is can lead to
opportunistic - targets immunosuppressed (most people carry on skin)
member of the coagulase negative staphylococci
causes infection in association with foreign bodies such as intravascular catheters, prosthetic joints as it adheres to metals and plastics using glycocalyx forming biofilms - hard to remove
describe the type of infection of streptococcus pyogenes
Group A Strep - most common cause of bacterial sore throat
can cause: - scarlett fever - strawberry tongue
necrotising fasciitis - common post delivery, pneumonia, puerperal sepsis
associated with secondary immunological presentations such as glomerulonephritis
what is the difference between strepto and staphy
staphy - bunch
strepto - chain
what does streptococcus pneumonia casue
most common cause of bacterial pneumonia and bacterial meningitis (except in neonates)
what is streptococcus agalactiae
group B strep
most common cause of bacterial meningitis and sepsis in neonates (babies aged under 3 months)
what is streptococcus milleri complex
three closely related species of pus-forming streptococci
associated with abscesses - dental, lung, liver, brain
what is viridian’s streptococci
collective name for species of a-haemolytic streptococci, inhabit upper respiratory tract (back of throat) eg S. oralis, S. mitis.
classic cause of sub-acute bacterial endocarditis - usually through tooth brushing (causes vegetation in the gums)
what is streptococcus gallolyticus
used to be SC bovis
type of a haemolytic streptococcus that forms part of the bowel flora
can cause bacteremia associated with colonic malignancies
what are the 3 types of gram positive bacilli
listeria monocytogenes
corynebacterium species
propionibacterium
what are listeria monocytogenes
rare but significant cause of sepsis and meningitis in pregnancy, neonates and immunsuppresed patient
disease which fester in animals (zoonosis) associated with consuming cheese made from unpasteurised milk and other foods
what are corynebacterium species
give an example
commensals of the skin and upper respiratory tract
opportunistic associated with devices and trauma
corynebacterium diphtheria, cause of diphtheria - contagious and fatal, can be immunised, insects nose and throat
what are propionibacterium acens
gram positive bacillus
associated with acne and can cause device/post procedural infections
what are the two types of gram negative cocci
neisseria meningitis
neisseria gonorrhoea
what is N. Meningitis
gram negative diplococcus
causes meningococcal sepsis and/or meningitis
classic presentation - purpuric non-blanching rash - purple discoloured rash which doesn’t disappear when you press it
(vaccinated)
what is N. gonorrhoea
gram negative diplococcus - cause of gonorrhoea
can cause opthahalmia neoatorum - mother has any time of birth and baby born with conjunctivitis
can cause invasive infections such as septic arthritis
what are the two types of gram negative bacilli
enterobactyeriacae (colifroms)
pseudomonos aeruginosa
what are coliforms
found in bowel flora - gram negative bacilli
eg E. coli - common cause of UTI, bacteraemia, nosocomial infections (hospital infections)
what type of coliform strain can cause severe diahorrea and haemolytic uraemia syndrome (HUS)
toxigenic colifroms eg O157
what is pseudomonos aeruginosa
multi resistant gram negative bacilli, opportunistic
can cause respiratory infections, UTI, soft tissue infections in vulnerable patients - often produces green pigment
what are the two types of gram negative coccobacilli
haemophilius influenza
anaerobes
what is H. influenza
gram negative bascilus
part of normal respiratory flora
causes respiratory tract infections including pneumonia and COPD
what do capsulated types of H influenza cause - how can they be prevented
type b
meningitis and epiglottitis
only type b infections prevented by HIb vaccine
what are anaerobes and give examples
grow in the absence of oxygen clostridium species C. difficile - antibiotic diarrhoea/colitis c. perfringens - gas gangrene c. tetani - tetanus c. botulinum - botulism
what is are the mycobacterium species referred as and give examples
acid fast bacilli ( AFBs) - luminous and don’t stain using conventional methods - don’t have bacterial wall
eg mycobacterium TB - night sweats, weight loss fatigue
can cause respiratory infections
what types of bacteria are chlamydia and M. pneumonia
mycobacterium as don’t have conventional cell wall
what are spirochetes
give examples
less conventional and do not easily gram stain
treponema pallidum - syphilis
can cause leptospirosis and lyme disease
