intestinal bacteria

Question 1

of the thousands of bacteria in the gut, how do we know which are clinically relevant

Answer 1

• causes disease in the GI system
• not part of healthy gut flora
• pathogen or opportunist?
• need treatment
• important for GI function and nutrition?
• are they gut commensals that would be pathogens at other sites
• will they cause food borne diseases

Question 2

the majority of the phyla firmicutes are what gram type

Answer 2

gram positive

Question 3

give examples of firmicutes

Answer 3

• mycoplasmas (lack cell wall)
• listeria
• staphylococcus
• enterococcus
• lactobacillus
• streptococcus
• clostridium
• bacillus

Question 4

members of the phylum bacteroidetes are what gram type

Answer 4

negative

Question 5

are bacteroidetes pathogenic

Answer 5

rarely, some evidence that bacteroides can cause opportunistic infections

Question 6

give 2 examples of bacteroidetes that are relevent to the GI system

Answer 6

• bacteroides
• porphyromonas

Question 7

members of the phyla proteobacteria are what gram type

Answer 7

negative

Question 8

list genera within the phyla proteobacteria

Answer 8

• escherichia
• salmonella
• vibrio
• helicobacter
• campylobacter

Question 9

list division of proteobacteria and genera withinneach division

Answer 9

only ones highlighted important

Question 10

give examples of genera within the phyla actinomycetota

Answer 10

• mycobacteria
• bifidobacterium (gram +)
• corynebacterium (gram +)

Question 11

list common genera of bacteria found in the GIT

Answer 11

Question 12

discuss bacteroides

Answer 12

• major component of the mammalian GI flora
• gram -
• bacilli
• anaerobes
• non endospore forming
• main source of energy is polysaccharides from plants but will use simple sugars also

Question 13

discuss lactobacillus

Answer 13

• gram +
• faculatative anaerobic/microaerophilic
• convert lactose and other sugars into lactic acid
• common and benign
• present on mucosa of repro and GIT
• makes environment acidic (bc produces lactic acid) which inhibits growth of some harmful bacteria

Question 14

discuss streptococci

Answer 14

• gram +
• coccoid
• facultative anaerobes
• from phylum firmicute
• grow in chains and paris because cellular division is on a single axis
• differentiate species based on haemolysis, serology, biochem testin
• can cause opportunistic disease

Question 15

discuss enterococcus

Answer 15

• gram +
• facultative anaerobe
• commensal
• important in terms of antibiotic resistance perhaps

Question 16

discuss clostridia

Answer 16

• gram +
• endospore forming
• rod shape
• obligate anaerobes
• causes botulism, tetanus, enterotoxaemia in sheep and goats, overgrows in rabbits treated with penicillins

Question 17

what factors can alter the normal balance of gut microflora

Answer 17

• medications
• stress
• diet
• genetics
• co-concurrent infection