bacteriology Flashcards
gram positive vs gram negative and what colour are they both in a gram stain
gram negative
- has thin peptidoglycan
- has lipopolysaccharide
- so stains pink
- mostly resistant to penicillins and vancomycin
gram positive
- retains blue black
- thick peptidoglycans
- some have spores
- mostly sensitive to penicillin and vancomycin
s.aureus type of bacteria
gram positive staphylococcus coagulase negative
how are s.a infections normally found
- pus forming
- blood stream
- often device related
- toxin illness
what are the coagulase negative staph
s.epidermidis and s.capitis normally only pathogenic in foreign body
3 types of gram positive coccus
- staphylococcus
- streptococcus
- enterococcus
what colour are the two beta haemolysis of strep
alpha= green
beta=gold
what is beta haemolysis group a strep
strep.pyogenes
-tonsilitis
strep throat
cellulitis
severe soft tissue infection
-puerpal sepsis
what is beta haemolysis group b strep
- strep.agalactiae
- normal rectal and vaginal flora
- neonatal meningitis, bacteraemia, pneumonia
- immunocompromised adults
2 main types of alpha haemolysis
strep.pneumoniae
virirdans
strep pneumoniae what does it cause
- CAP
- meningitis
- bronchitis in COPD
what are the viridans strep
-commensal or mucosal flora that stick to things eg heart valves causing endocarditis
what are the enterococci bacteria found and hwere
- in the gut
- involved in intra-abdominal sepsis, UTI and bacteraemia
what does VRE stand for
vancomycin resistant enterococci
3 gram positive bacilli
- bacillus
- corynebacterium
- listeria
reservoir for anthracis and what they cause and transmission
- reservoir of soil and domestic antimals herbivores eg cows
- human infected by cutaneous inoculation IVDU or inhalation
- cause anthrax disease= get small blisters and fever, chest pain
corynebacterium diptheriae
- transmission
- pathology
- prevention
- spread person to person by respiratory droplets
- bacteria in pseudomembrane in throat: potential suffocation
- diptheria toxin produced in throat, via bloodstream then inhibits protein synthesis in heart (cardiac failure) and peripheral nerve
what do listeria monocytes do and where are they found
-intrauterine/ neonatal septicaemia/ meningitis
risk in pregnancy from foods like
-soft cheese
-coleslaw
gram positive anaerobes 4 types
- coccus
- bacillus: clostridia
4 main types of clostridia
- clostridium tetani
- clostridium botulinum
- clostridium difficile
- clostridium perfringens
clostridium tetani
- transmission
- pathology
- symptoms
- prevention
-transmission: spores ubiquitous in soil, soil then contaminates
-toxin mediated neuro-toxin causes excitation of motor neurones by blocking release of inhibitor GABA
SYMPTOMS: spasm, rigidity
prevention: vaccine
clostridium botulinum
- reservoir
- pathology
- symptoms
- prevention
- reservoir: food borne as germinates in soil
- toxin: neuro-toxin prevents release of acetylcholine
- symptoms: symmetrical flaccid paralysis
- prevention: standards of food prep
clostridium difficile
-transmission
ingestion in spores
from soil
clostridium perfringens
-infections
transmission
pathology -main toxin
- gas gangrene and other ssti
transmission: sores in soil to human gut - toxin mediated disease: main toxin is alpha toxin- lecithinase so damages cell membrane including haemolysis
what are the gram negative aerobic cocci
neisseria gonorrhoea
neisseria meningitidis
moraxellla cattharalis
other(commensal) neisseria in mouth
what is a coliform
also called the enterobacteriaceae
- bacteria that are rod shaped gram negative non-spore forming which can ferment lactulose eg
- e.coli
- klebsiella
- salmonella
what is the commonest aerobic GNB in the gut
e.coli
what is the VTEC strain of e.coli
e.coli 0157 causes haemorrhage can lead to HUS haemorrhagic uraemic syndrome
what are the main causes of UTI
e.coli
klebsiella
reservoir shigella
humans only
reservoir salmonella
multiple species whose host include all mammals, birds and reptiles
-faeces spread in humans in water
pseudomonas aeruginosa reservoir
-pathology
and who it affects most
- environment especially water
- human respiratory pathogen where biolfilms important
- immunocompromised eg CF, long term lung conditions
- common coloniser eg leg ulcers
burkholderia cepacia
- reservoir
- who it affects
- reservoir soils and plants
- now a pathogen in CF
vibrio cholerae
- reservoir
- toxin pathology
- pathology
- treatment
reservoir: warm salt water and spread by faeces
- toxin mediated disease: increased cAMP in cells, decrease in Na uptake and increased Cl secretion
- massive water loss and rice water stools
- electrolyte problem
what is the commonest bacterial cause of gastroenteritis in the UK
-campylobacter found in birds
what does h.influenzae cause 2 types
- unencapsulated strains are common cause respiratory tract infections
- capsulated serotype b causes meningitis in young children
what does leigonella cause and where is its reservoir
- causes severe pneumonia
- lives in natural and engineered water systems inside amoebae
what does helicobacter produce
urease breaks down urea to ammonia to buffer stomach conditions
what do bacteroides cause
assoc. to intrabdominal and ssti infections
resistant to penicillin
what do fusobacterium cause
- head and neck infections including brain abscesses
- mixed intra-abdominal infection
- perirectal abscess
3 small bacteria
- chlamydia
- mycoplasma pneumoniae
- rickettsia
how are the small bacteria different to other bacteria
smaller
dont grown on agar plate
lack normal cell wall
what is rickettsia and what cells does it like
obligate intracellular parasites
likes endothelial cells with skin lesions and vasculitis
what does chlamydia trachoma cause
chronic eye infection
what does chlamydophila pneum and chlamydophila psittaci cause
both cause pneumonia
psittaci in birds
