gram negative bacteria

2. 1. Veilonella
Morphology
 Small cocci
 Gram negative cocci
 Non motile
 Non sporing
 0.3-0.5 mm in diameter
 Occuring in pair, short chins or in clumps

3.  Anaerobic cocci
 Appearing by light microcopy as diplococci,
masses and short chain
 Colonies may fluoresce red under UV light
 Optimum temperature is 30-350c
 Optimum pH is 6.5-8
 Present in normal flora of the mouth, GI tract
 This bacterium is well known for its lactate
fermenting abilities

4.  Catalase negative
 Some species produce catalase lacking
porphyrin
 Pyruvate, malate, fumarate and oxaloacetate
are fermented
 Acetate, propionate, CO2 and H2 are produced
 Veillonella cocci reduce nitrate

5.  Fermentation of lactate to propionate and
acetate by methyl malonyl-coA pathway
 ATP is produced
 High substrate affinity
 3 lactate acetate+2propionate+CO2+H2O

6.  These organism also inhibited bile, kanamycin,
colistin.
 Isolated in polymicrobial anaerobic infection
 Produced serologically specific endotoxin that
induce pyrogenicity and Schwaltzman
phenomenon in rabbits
 Veillonella resistant to vancomycin, tetracyclin,
aminoglycosides and ciprofloxacin.

7.  it is non pathogenic cocci
 These organism are parasitic in mouth,
intestinal and respiratory tract of humans and
other animal
 Rarely, veillonella species have been the only
etiologic agent identified in seroius infection
such as;
 Meningitis
 Osteomyelitis
 Prostheitc joint pain
 endocarditis

8.  Gram negative diplococci.
 0.6-1µm oval with flattened adjacent sides.
 Moraxella includes M.catarrhalis and
M.lacunata.
 M.catarrhalis is a harmless commensal of upper
respiratory tract.
 It grows in basal medium like nutrient agar

9.  Oxidase and catalase positive.
 It differ from pathogenic Neisseria as.
 It does not ferment any carbohydrate.
 Give a positive tributyrin hydrolysis test.
 Shows Dnase test positive

10.  It causes opportunistic lower respiratory tract
infections especially in adults with chronic
obstructive airway disease.
 It has also been notated in case of otitis
media, less commonly in meningitis,
endocarditis and ………………
 Some strains of M.catarrhalis secrete β
lactamase which destroy penicillin that make
β lactum antibiotic

11.  Oxidase positive
 Not produce acid from sugars
 Produce DNase
 Hydrolyze tributyrin
 Grow on medium lacking blood

12. Morphology and staining
 Oval gram negative cocci are about 0.8 um in
diameter.
 They are seen in single or in pairs with adjacent
sides flattened.
 Occasionally they found in groups of four as a
result of division in two successive planes.
 Sometimes they may be found inside
polymorphonuclear leukocyte.

13. Cultural characteristics
 Optimum temperature of aerobe is 360c but
many strains grows in 220c.
 Grow on nutrient agar
 Colonies on blood or heated blood agar are;
1-2mm in diameter
non hemolytic
friable
white or greyish
convex

14.  After 48hrs the colonies are;
Large
More elevated with raised opaque center
Biochemical reactions
 Oxidase positive
 Not produce acid from glucose, maltose,
sucrose lactose or fructose.
 Reduce nitrite to nitrite
 Hydrolyses tributyrin

15.  More resistant than the meningococcus or
gonococcus.
 Culture may remain viable for several months
for 200c.
 May survive in sputum for 3-4 weeks
 Susceptible for a wide range of antibiotics
 Resistant to penicillin and ampicillin
 Sensitivity test can be done by disc or dilution
methods

16. Gram positive non sporing anaerobic bacilli
 species are commensals in mouth and
intestine.
 They are rarely pathogenic.
 Eubactecterium,Bifidobacterium and Arachnia.

17.  Non motile gram negative bacilli
 Show bipolar and barred staining
 They are distributed as saprophytes
 They can ferment milk and cheese
 They produce lactic acid from carbohydrate and
grow in the pH of <5
 Part of normal flora of mouth, gut and vagina

18.  Lactobacilli in the stomach synthesize
vitamins such as biotin, vit B12, vit K.
 In the oral cartrige these have role in the
pathogenesis of dental caries
 It forms acid by the fermenttion of sucrose
and other dietary carbohydrate which
dissolve the mineral components of enamel
ant dentine
 In vagina, it produce lactic acid that maintain
the acidic Ph of the adult vagina protecting
from various infections

19.  Peptoocus: one species; P.niger which occur
 as gram positive cocci
 Distributed singly or in pair or in cluster
 It produce black colour on blood agar and
also produce H2S

20.  Peptostreptococcus: gram positive cocci
occur in pair or in chains
 Has many species
 Both peptococcus and peptostreptococcus
are normal flora of skin, mouth,intestine and
vagina

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