bacterial pathogens

Question 1

what bacteria is MRSA?

Answer 1

staphylococcus aureus

Question 2

what is responsible for rheumatic fever and what is a symptom?

Answer 2

streptococcus pyogenes and can give a fever

Question 3

what does streptococcus agalactiae result in?

Answer 3

neonatal meningitis and pneumonia and sepsis - group B strep

Question 4

what causes gonorrhoea and what is another name for gonorrhoea?

Answer 4

urethritis and is from steptococcus gonorrhoeae

Question 5

what causes UTIs?

Answer 5

proteus

Question 6

what is clostridium difficile?

Answer 6

it is antibiotic related diarrhoea, PMC

Question 7

what does barrielia and leptospira result in?

Answer 7

barrielia - relapsing fever

leptospira - meninigitis

Question 8

what do S and R in a blood culture report mean?

Answer 8

S means sensitive and R means resistant

Question 9

what will happen to gram stain with a thick cell wall?

Answer 9

the cell wall will retain the gram stain - gram positive

Question 10

what are the characteristics of a cell wall in a gram negative bacteria?

Answer 10

thin cell wall - they will contain lipopolysaccharides - fatty outer cell membrane layer

Question 11

which one is more common on skin?

Answer 11

positive - they are more resistant to drying, negative will only survive in places with more moisture

Question 12

what shape are bacilli and cocci?

Answer 12

bacilli are rods and cocci are circular

Question 13

what are examples of virulence factors?

Answer 13

resistance factors or enzymes to break tissue down - they are designed to help the bacteria invade the host tissue

Question 14

what does invasion depends on?

Answer 14

host factors, bacterial factors and opportunity (distance, exposure)

Question 15

why are females more prone to UTIs?

Answer 15

they have a shorter urethra

Question 16

why is E coli the commonest cause of UTIs?

Answer 16

E coli is normal flora in the bowel. It can ascend in the perineum by colonising the urethral meatus and then adheres to the urinary cells or urethral catheter equipment causing an inflammatory response and can develop resistance to antibiotics

Question 17

what is the commonest form of skin and soft tissue infections and how does this occur?

Answer 17

S. Aureus - it adheres to damaged skin and secretes exoenzymes and toxins which can damage cells or promote the host inflammatory response such as pus. it can colonise the nasal carriages of up to 50% of people

Question 18

what are some examples of diseases Staphylococcus aureus can cause?

Answer 18

UTIs, meningitis, pneumonia, endocarditis, osteomyelitis, septic arthritis, bacteriaemia or septicaemia

Question 19

what does S aureus look like with a gram stain?

Answer 19

a bunch of grapes - clusters formed

Question 20

what is staphylococcus epidermidis?

Answer 20

it is an opportunistic bacteria, commensal on skin - most people have it. It is described as a coagulase negative staphylococci

Question 21

when can eidermidis strike?

Answer 21

associated with foreign bodies such as lines and prosthetic cardiac valves - needs an opportunity to infect

Question 22

why does it infect with lines etc?

Answer 22

it can adhere to plastics or metals using glycocalyx and form biofilms - loosen bones and joints resulting in pain and instability

Question 23

what are the differences between aureus and epidermidis?

Answer 23

epidermidis is more internal and has different pathogenicity factors

Question 24

what bacteria is included in group A strep?

Answer 24

streptococcus pyogenes - commonest cause of bacterial sore throat

Question 25

what can strep pyogenes cause?

Answer 25

puerperal sepsis, SSTIs, necrotisin fasciitis, scarlet fever and invasive infections such as pneumonia and is also associated with secondary immunological presentation - glomerulonephritis (autoimmune as have antibodies to strep A group)

Question 26

what is the presentation of pyogenes with gram stain?

Answer 26

purple chains - gram positive

Question 27

what is a common cause of childhood infections such as otitis media, bacterial meningitis and bacterial pneumonia?

Answer 27

streptococcus pneumoniae

Question 28

what strep causes abscesses (dental, liver, lung, brain?)

Answer 28

streptococcus milleri complex

Question 29

what are viridans streptococci?

Answer 29

collective name for a number of species of a-haemolytic streptococci that inhabit the upper respiratory tract - classic cause of sub-acute bacterial endocarditis

Question 30

how do viridans streptococci work?

Answer 30

they adhere to areas of damage and alter blood flow around the heart valves giving aortic stenosis and disease of the heart valves

Question 31

what strep forms part of the bowel flora, is a-haemolytic and was formerly known as streptoccocus bovis?

Answer 31

streptococcus gallolyticus - casues bacteriaemia and can be associated with colonic malignancies

Question 32

what is listeria monocytogenes?

Answer 32

it is a gram positive bacillus - it is rare but is a significant cause of meningitis and sepsis in pregnancy, neonates and immunosupressed patient

Question 33

what is an adaptive feature of listeria monocytogenes?

Answer 33

ti is zoophilic - animal origin so can grow at low temperatures

Question 34

what is the corynebacterium species?

Answer 34

it is a rarely seen bacteria (unless in some parts of the world) that is a gram positive bacilli and is a commensal (some species)on the skin or URT.

Question 35

why is diptheria not seen in the UK?

Answer 35

due to the vaccination - targets corynebacterium diptheriae

Question 36

what is enterobacteriacae?

Answer 36

it is a collective term for a group of species that are gram negative bacilli and are commensal in the bowel

Question 37

what are the commonest sources of bacteriaemia from E coli?

Answer 37

urinary, biliary or intra-abdominal

Question 38

what are toxigenic strains of E coli associated with?

Answer 38

severe diarrhoea, and haemolytic uraemia syndrome

Question 39

what is psuedomoas aeruginosa?

Answer 39

it is a multi-resistant gram negative bacillus that is an opportunistic pathogen. It often colonises leg ulcers but this can be wiped off but more commonly causes respiratory, UT, soft tissue and other infections in vulnerable patients and produces a characteristic green pigment

Question 40

what is neisseria meningitidis?

Answer 40

it is a bacteria that can cause mengiococcal sepsis and or meningitis. It is a gram negative diplococcus and the infection is not as serious as that of strep. the classical presentation is a purpuric non blanching rash - reduction in cases since vaccination - B and C

Question 41

what is a complication and a rare complication of neisseria gonorrhoeae?

Answer 41

rare - other secondary invasive infection such as septic arthritis complication - baby born to mother with active illness can get form of conjunctivitis

Question 42

what type of haemophilius influenzae (gram negative bacilli) causes epiglottis damage or meningitis?

Answer 42

capsulated types | type b is capsulated and is the only one that is in the Hib vaccine

Question 43

what are the four infections caused by the main types of clostridium and what type of bacteria are these?

Answer 43

clostridium are anaerobes of which many are spore forming. C difficile causes antibiotic related diarrhoea or colitis, C tetani tetanus, C botulinum it botulism and C. perfringens classically causes gas gangrene

Question 44

what are some types of anaerobe species?

Answer 44

prevatella, fusobacterium, and bacteroides - often part of polybacterial infections

Question 45

what is often referred to as acid fast bacilli?

Answer 45

mycobacterium species as they use acid fast stain

Question 46

why do mycobacterium not use the classic gram stain?

Answer 46

their cell wall does not allow for staining

Question 47

what are atypical mycobacteria and what do they cause?

Answer 47

they are another species of mycobacterium and they cause respiratory infections in chronic lung disease and opportunistic infection in the immuncompromised

Question 48

what are the species without a cell wall and what are examples?

Answer 48

these are the chlamydia and mycoplasma species C. trachomatis - commonest cause of STI in uk mycoplasma pneumoniae - comments cause of respiratory tract infection

Question 49

what do spirochaetes not do?

Answer 49

they do not stain with gram stain such as treponema pallidum (syphilis)

Question 50

what causes lyme disease and leptospirosis?

Answer 50

spirochaetes lyme - chronic fatigue syndrome leptospirosis - renal failure and meningitis