Download Non Enteric Gram negative rodes

NON ENTERIC GRAM NEGATIVE
RODS
PSEUDOMONAS SPP
HAEMOPHILUS SPP
BRUCELLA
MYCOBACTERIA
Pseudomonas aeruginosa
 Is
widely distributed in nature and is commonly
present in moist environment in hospitals.
 It can colonize normal human, in whom it is a
saprophyte.
 It cause disease in immuno-compromised
individuals or when they gain access to a
normally sterile body site through trauma
( it is an opportunistic pathogen).
Cont/..Pseudomonas aeruginosa
Microscopical appearance :
 Gram-negative rods, Motile (by single or
multiple polar flagella) ,measuring 0.6*2 µm.
 Occurs as single bacterium, in pairs,
occasionally as short chain
Cont/.. Pseudomonas aeruginosa
 Cultural
(Macroscopic) characteristics: Pale
white or translucent colonies .Circular, convex,
and smooth colonies. Obligate aerobes, grow
readily on many types of media, on blood it gives
β-hemolysis, sometimes producing a sweet or
grape -like odor.
Cont/.. Pseudomonas aeruginosa
Exopigments:
Many strains of P aeruginosa produce:
Fluorescent greenish color
pyoverdin
It often produces:
non-fluorescent bluish pigment
pyocyanin
Some strains produce:
Dark red pigment pyorubin or black pigment pyomelanin
Cont/.. Pseudomonas aeruginosa
It grows well at 37-42 °C; its growth at 42 °C helps
differentiate it from other Pseudomonas spp in
the flourescent group.
 Biochemical
Tests :
Oxidase Test =+ve,
 IMViC= _ _ _+ ,
 Gelatin = +ve,
 TSI = - - -  Catalase =+ve
 It does not ferment carbohydrates, but many strains
oxidize glucose

Summary
Identification of P aeruginosa is based on
1-colony morphology
2-oxidase positivity
3-the presence of characteristic pigments
4-growth at 42 °C
Haemophilus spp
The most common type of Haemophilus spp. is type b H
influenzae.
Microscopical appearance:
Gram-negative, pleomorphic, coccobacilli, non motile. Some
strains are capsulated some are not. The organisms are short
(1.5 µm).
Cont/…Haemophilus influenzae
Cultural(macroscopical) characteristics:
This microorganism is very fastidious in its growth that need
enriched media. The preferable medium for culturing
Heamophilus spp is chocolate agar on which it would give
flat, grayish – brown colonies with diameter of 1-2mm at
37°C
Cont/…Haemophilus influenzae
Growth characteristics
On blood agar, Haemophilus group required certain growth
factors called X factor( that would act as Hemin);and ̸ or V
factor that would act as a coenzyme (NAD or nicotinamide
adenine nucleotide)
Cont/…Haemophilus influenzae
These growth requirements are used for differentiation of
Heamophillus spp.
species
Requires
X
V
Hemolysis
H influenzae
+
+
-
H parainfluenzae
-
+
-
+
+
+
H haemolyticus
Cont/…Haemophilus influenzae
It can grow around Staphylococcus aureus streak yielding
the satellite phenomenon because Staphylococci would
cause the release of NAD and the Hemin from the blood in
the agar which allow the Heamophilus to grow just around
the colonies of Staph.
Cont/…Haemophilus influenzae
Biochemical test:
Catalase: positive
Oxidase: positive – slow reaction.
Brucellae spp
The Brucellae are obligate parasites of
animals
and
humans
and
are
charecterisically located intracellularly.
The disease in human is brucellosis (Malta
fever).
Brucellosis is a zoonotic disease caused by
any of four Brucellae species.
Cont/..Brucellae spp
Microscopical appearance:
Gram negative coccobacillary , aerobic , non motile, non
spore forming.
Cont/..Brucellae spp
Cultural(macroscopical ) appearance: Cultured on
blood agar and chocolate agar. Grows as tiny gray-white,
shiny ,small convex colonies on blood agar. Brucellae utilize
carbohydrate without gas or acid production.
It is a slow growing m.o. that necessitate a rapid method for
identification by using serological method (Rose Bengal test).
Cont/..Brucellae spp
Biochemical test :
 Catalase =+ ve,
 oxidase =+ ve,
 nitrate reduction= +ve .
 urease =+ ve
 No carbohydrate fermentation.
Cont/..Brucellae spp
 Serological

test(indirect latex agglutination):
1-The Rose Bengal Test (RBT) is the most widely used
screening test for brucellosis in both humans and animals
owing to its apparent simplicity of reading .
Principle of the test:

A rapid agglutination slide test for the detection of Brucellae
specific antibody. A suspension of Brucellae possessing active
antigen will agglutinate when exposed to homologous
Brucellae antibody. This agglutination forms clumps of
bacteria which becomes macroscopically visible. The Rose
Bengal stained Brucellae antigen is used for the early
detection of Brucellae.
Cont/..Brucellae spp
THE ROSE BENGAL TEST (RBT)

The reagent: Rose Bengal ( rose color stain)
Result:
Negative: No agglutination

Positive: (Presence of Specific Antibodies) agglutination.

 2-
brucilline skin test: non specific used in chronic
cases give an indication for past or present infection.
Mycobacteria spp
The mycobacteria are rod-shaped, aerobic, non-spore
forming bacteria.
Mycobacterium tuberculosis
Microscopical appearance:
Thin straight rods measuring about 0.4x3 µm.
Mycobacteria cannot be classified as either gram +ve or
gram –ve.
Tubercle bacilli are characterized by “acid-fastness”-ie,
95% ethyl alcohol containing 3% HCl (acid-alcohol)
quickly decolorizes all bacteria except the mycobacteria.
Acid-fastness depends on the integrity of the waxy
envelope.
The Ziehl-Neelsen (acid-fast) stain is used for
identification of acid-fast bacilli.
Cont/…M tuberculosis
Macroscopical appearance:
Culturing of mycobacteria requires both a non-selective
and a selective media. Selective media contain
antibiotics to prevent overgrowth of contaminating
bacteria and fungi.
There are three general formulations :
1- Semisynthetic Agar Media (eg, Middlebrook 7H10).
2- Inspissated Egg Media (eg, Lowen-stein-Jensen).
3- Broth Media (eg, Middlebrook 7H9).
Growing of Mycobacteria on these media is slow and
requires prolonged time (over weeks).
Tuberculin skin test:
Principle: a large amount of tuberculin injected IC into
hypersensitive host may give rise to severe local
reaction.
An individual who has had a primary infection with
tubercle bacilli develops induration, edema and
erythema within 24-48 hrs. The test should be read in
48-72 hrs.
In a person who has not had contact with tubercle bacilli,
no reaction to the skin test results.