Classification of pathogenic bacteria

Question 1

what is in bacterial cell wall

Answer 1

peptidoglycan

Question 2

how to classify different bacteria

Answer 2

cell wall

Question 3

which cell wall is more complex

Answer 3

gram negative but it has less peptidoglycan

Question 4

colour of gram positive stain and why

Answer 4

purple, crystal violet can make complexes within peptidoglycans

Question 5

types of gram positive bacteria shape

Answer 5

cocci (round), bacilli (rods)

Question 6

arrangements of cocci

Answer 6

streptococci-chains, staphylococci- clusters

Question 7

staphylococci can be differentiated according to whether they are

Answer 7

coagulase positive or negative

Question 8

staphylococcus aureus

Answer 8

commensal organism carried in nose, axilla and perineum. one of the most important bacteria. wide range of diseases. also colonise harmlessly. commonly penicillin resistant and some are methicillin resistant

Question 9

biofilm related infections

Answer 9

biofilm is formed by coagulase negative staphylococci and it is a complex microbial community that forms over foreign objects. harder to treat as bacteria is protected inside biofilm and antibiotics cannot get through to it

Question 10

coagulase negative staphylococci

Answer 10

staph epidermis and staph saprophyticus mainly skin commensals

Question 11

three forms of streptococci

Answer 11

alpha haemolytic (turns blood agar green), beta haemolytic (turns blood agar clear), non haemolytic (no difference)

Question 12

group A strep

Answer 12

streptococcus pyogenes- very severe, can cause pharyngitis, necrotising fasciitis, needs surgery as well as antibiotics

Question 13

group B strep

Answer 13

streptococcal bacteria mainly causes neotnatal sepsis and sepsis in older individuals with underlying medical conditions

Question 14

C difficile

Answer 14

gram positive bacilli, anaerobic, difficult to culture, high percentage of people have it colonised in gut but asymptomatic, can release toxins and cause disease, releases spores

Question 15

C perfringens

Answer 15

gram positive bacilli, found in soil and commensal in faces, gastroenteritis, gas gangrene in infected wounds, releases soores

Question 16

types of bacilli to know

Answer 16

difficiles, perfringens, tetani, botulinum

Question 17

4 most important gram positive bacteria

Answer 17

straphylococcus aureus, streptococcus pyogenes, streptococcus pneumoniae, clostridium difficile

Question 18

types of gram negative bacteria

Answer 18

e coli, Neisseria meningitidis (cocci), salmonella, curved bacilli, bacteroides, helicobacter, coliforms

Question 19

coliforms

Answer 19

gram negative bacilli, organisms in the family enterobacteriaceae and colonise in the gut, lactose fermentation test for classifying

Question 20

Escherichia coli

Answer 20

gram negative bacteria- coliform, vast number of virulence mechanisms, human and animal, ferments lactose, cause UTI and many other diseases

Question 21

curved gram negative bacilli

Answer 21

campylobacter spp, commonest cause of diarrhoea in uk, faecal oral route, microaerophilic, source is domestic animals and chickens eating, foul smelling or bloody diarrhoea

Question 22

pseudomonas spp

Answer 22

gram negative. water and soil coloniser, can contaminate hospital equipment, can cause UTI, sepsis, pneumonia, feared pathogen in cystic fibrosis, multi drug resistant

Question 23

anaerobes

Answer 23

in oral cavity and gastrointestinal tract, part of polymicrobial infection, bacteroides fragilles- in gut, may spread to other sites, causes intra abdominal abscess

Question 24

miscellaneous bacteria

Answer 24

chlamydia, spirochaetes, mycobacterium spp- tuberculosis caused