LAB - Nonfermenters and Campylobacter Flashcards
Brownian movement
passive
not true motility
jerky/oscillatory movement usually in one spot or lacking direction
non fermenters that may oxidize carbs
oxidative (saccharolytic)
bacteria that do not break down carbs at all
asaccharolytic
non-fermenting gram neg bacilli prefer these growing conditions
- moist aerobic
- ubiquitous = soil, water, on plants, decaying vegetation
non-fermenting gram neg bacilli characteristics
- oxidase po
- TSI K/K or no change
- MAC is wh or ng
cause of “hot tub rash”
P. aeruginosa
pigment produced by P. aeruginosa
pyoverdin and pyocyanin
Campylobacter characteristics
- g- spiral rods
- microaerophilic
- most common cause of human gastroenteritis
- corkscrew, darting motility
- oxidase pos
- catalase pos
- selective CAMP media
oxidation of glucose
- bacteria produce acids from carbs in aerobic conditions
- glucose oxidized to gluconic acid
- weak acid; only 1 molecule of acid produce from 1 molecule of glucose
fermentation
- anaerobic process
- glucose first phosphorylated then split into two triose molecules
- further rxns = one or more acids = lactic, formic, succinic, or acetic acid
- more rapid than oxidation
O-F test
determines if a sugar is attacked by oxidation or fermentation
- one sealed wth mineral oil for anaerobic conditions while other tube is loosely capped for aerobic
extracting oxygen from nitrates to form nitrites and other reduction products
nitrate reduction
reagent A and B in nitrate reduction test
A = sulfanilic acid B = dimethyl-alpha-naphthylamine
denitrification
when nitrates are reduced beyond nitrites to products such as ammonia, nitrogen, nitric oxide, or nitrous acid and hydroxylamine
- usually an accumulation of gas in a Durham tube
Fluorescein
- pyoverdin production by P. aeruginosa
- yellow-green diffusible, fluorescent pigment which is NOT soluble in chloroform,
- most strains of P. aeruginosa
- pigment production (+ fluorescence) noted by viewing BAP culture under short wave UV light
Pyorubin production
- P. aeruginosa
- brown to red in colour
Pyomelanin
- P. aeruginosa
- brown in colour
Pyocyanin
- P. aeruginosa only species that can produce this
- blue-green, diffusible, non-fluorescent pigment which is soluble in chloroform
- characteristic metallic sheen on BAP
why do we add zinc ions to test for nitrate reduction?
if added to negative tests, zinc ions will reduce nitrate if it is still present = red colour
confirms negative test!
non-fermenters
gram-negative bacilli that are either incapable of utilizing carbs as a source of E or degrade them via oxidative metabolic pathways
- white/no growth on MAC
- positive oxidase
- K/K on TSI (glucose not fermented)
screening test for non-fermenters
- oxidase
- motility
- O-F
followed by commercial identification systems (API, Micro-scan, Vitek, MALDI-TOFF)
P. aeruginosa is most commonly isolated in…
sputum of cystic fibrosis patients
jacuzzi or hot tub syndrome
P. aeruginosa
otitis external or swmmers ear
P. aeruginosa
tests to confirm P. aeruginosa
- positive growth at 42C
- nitrate reduction (denitrification)
- pigment production
most common cause of human diarrheal disease esp. in children
C. jejuni
special methods required to isolate C. jejuni from fecal specimens
- 7% lysed sheep/horse blood
- several antibiotics to inhibit normal enteric flora growth
- plates incubated at 42C for 48 hours (5-10% O2,3-10% CO2)
