Bacteria

Question 1

characteristics of prokaryotes

Answer 1

• no DNA within nuclear membrane
• no DNA associated with histones
• no membrane bound organelles
• no mitotic divisions
• 1 chromosome
• 70 s = chromosome size
• cell wall containing peptidoglycan present

Question 2

characteristics of gram positive bacteria and stains

Answer 2

• thick, multiple peptidoglycan layers
• contains teichoic acid which constitutes major surface antigens
• stains blue to purple-blue because decolorization does not get rid of primary stain

Question 3

Characteristics and causes of positive gram bacteria Staphylococcus aurens

Answer 3

found in areas with hair (nasal cavity, groin, inguinal area, axilla, hairline)
causes a lot of infections
causes:
- pneumonia
- osteomyelitis
- infective endocarditis
- soft tissue infections
- septicemia
- food poisoning

Question 4

Characteristics and causes of positive gram bacteria Coagulase negative Staph

Answer 4

found in normal skin commensals
causes opportunistic infections in patients with:
- catheters
- IV fusions
- orthopedic prosthesis
- artificial cardiac valves

Question 5

Characteristics and causes of positive gram bacteria streptococci

Answer 5

found in URT
streptococcus pyogens
- rheumatic fever and heart disease (autoimmune disease if not treated)
- otitis media
- pharyngotonsilitis
- soft tissue infection
- scarlet fever
streptococcus pheumoniae
- common cause of pneumonia in HIV/AIDS patients
- children used to struggle before there was a vaccine
- pneumonia
- meningitis
- sinusitis

Question 6

Characteristics and causes of positive gram bacteria Enterococci

Answer 6

found in GIT
causes:
- enterococcus faecalis
- enterococcus faecium
- UTI and infective endocarditis
- wound infections

Question 7

Characteristics of gram negative bacteria and stains

Answer 7

stains pink/red
- discoloration causes primary stain to disappear and bacteria takes on second stain
contains 2 layers:
1. thin peptidoglycan layer
2. outer-membrane containing porines
- lipopolysaccharide containing lipid portion and polysaccharide chain
- NB because when released from cell wall it is toxic to mammals and causes:
- fever
- changes in white blood cell count
- cytokine release
- disseminated intravascular coagulation
- decreased BP leading to vascular collapse, shock and death

Question 8

what are some clinically NB gram positive bacilli

Answer 8

spore forming
- bacillus
- clostridium
non-spore forming
- corynebacterium
- listeria
- lactobacillus
bacilli with branching filaments
- actinomyces
- nocardia
defirium
- life threatening, causing URTI
- medical emergency

Question 9

characteristics of non-spore forming positive bacteria bacilli listeria

Answer 9

• one of causes of neonatal sepsis/ meningitis (mom to child infection)
• not killed by cold temperatures

Question 10

Characteristics and causes of gram negative bacteria pseudomonas

Answer 10

• bacilli
• likes moist environments
• common cause of infection in burns patients
  found in
• soil, water, sewage
• usually hospital acquired
  causes
• LRTI
• chronic otitis externa
• secondary eye infections
• infections on pressure sores, varicose veins. ulcers
• catheters (UTI)
• mechanical ventilation

Question 11

Characteristics and causes of gram negative bacteria Acinetobacter

Answer 11

• bacilli
• resistant to multiple antibiotics
• can survive for long periods in an environment
  found in
• environmental organisms
• infections in hospitalised and immunocompromised patients, especially those in ICU
  causes
• colonizes intravascular catheters or other invasive devices

Question 12

Characteristics and causes of gram negative bacteria escherichia coli

Answer 12

• bacilli
  found in
• normal flora of GIT
  causes
• UTI
• wound infections
• peritonitis
• septicemia
• neonatal meningitis

Question 13

Characteristics and causes of gram negative bacteria Klebsiella

Answer 13

• bacilli
  found in
• normal GIT flora
• saprophyte in soil, water and plant material
• hospital wash basins and baths
  causes
• most NB: Klebsiella pneumoniae
• UTI
• septicemia
• meningitis esp. neonates, young children
• abscessess
• pneumonia

Question 14

Characteristics and causes of gram negative bacteria Shigella

Answer 14

• bacilli
  found in
• not normal flora
• person to person transmission
• highly infectious
  causes
• dysentery
• high secondary attack rate

Question 15

Characteristics and causes of gram negative bacteria Salmonella

Answer 15

found in
- non-typhoidal is acquired via ingestion of contaminated animal products
- Salmonella typhi (reservoir, person to person transmission)
causes
- non-typhoidal: GIT disease
- salmonella typhi: enteric fever
- salmonella species can also cause focal infections

Question 16

Characteristics and causes of gram negative bacteria proteus species (especially proteus mirabilis), enterobacter species

Answer 16

found in normal flora of GIT
causes
- HAI
- wound infections
- line infections
- UTI
- ear infections

Question 17

Characteristics and causes of gram negative bacteria neiserra meningitidis (meningococcus)

Answer 17

• diplococcus
• transmitted by droplet spread
• causes meningitis, sepsis and focal infections
• high mortality if not treated immediately and appropriately
• highly contagious
• notifiable disease
• isolation, standard and droplet precautions
• pep given
• vaccine available but not part of immunization program

Question 18

characteristics of normal flora

Answer 18

non-pathogenic microorganisms found on mucosal surface and skin
relationships:
- mutualism
- commensalism
delays in transporting a specimen to the lab for processing impacts on culture results as normal flora overgrows preventing proper diagnosis of infections

Question 19

Advantages and Disadvantages of GIT normal flora

Answer 19

advantages
- assist digestion of food
- protect from colonialization by pathogens
- activate immune response
disadvantages
- cause disease when entering sterile site
- opportunistic pathogens

Question 20

What factors affect normal flora

Answer 20

• antibiotic treatment
• diet
• stress
• host response to flora

Question 21

define commensals

Answer 21

organisms living in a relationship in which one organism derives benefits e.g. nutrients from another without harming it

Question 22

define colonization

Answer 22

continued presence of organism on body sites without causing damage/invasion

Question 23

define infection

Answer 23

damage/invasion of host tissues associated with organisms

Question 24

define infection by primary pathogen

Answer 24

cause infection in patients with normal immunity and is highly virulent

Question 25

define infection by opportunistic pathogen

Answer 25

cause infections in patients with depressed immunity/ when normal flora gain entry into sterile site

Question 26

define virulence

Answer 26

ability of an organism to cause disease: mainly evading/ overstimulating host immune response

Question 27

define reservoire

Answer 27

where an organism/ pathogen lives and multiplies

Question 28

define source

Answer 28

site from which an organism/ pathogen spreads to host, objects

Question 29

What is infection control and prevention

Answer 29

Inventions/measures, practices, guidelines protocols aimed at
- prevention
- early identification
- control of infections in health care settings and/or community

Question 30

What are community acquired infections

Answer 30

Infections due to everyday exposure to microorganisms in the community