slide 2  Commonly present in large intestine •  Non sporing ,  Non Acid fast,  Gram – bacilli. •  A complex family of organisms, •  Some are non pathogenic •  A few are highly Pathogenic, •  Some commensals turn out to be pathogenic as in UTI after catheterization. slide 3  Characters of Enterobacteriaceae •  All Enterobacteriaceae a) – Gram-negative rods b) – Ferment glucose with acid production c) – Reduce nitrates into nitrites d) – Oxidase negative  Facultative anaerobic  Motile except Shigella and Klebsiella  Non-capsulated except Klebsiella  Non-fastidious  Grow on bile containing media (MacConkey agar  slide7 Conserved signature inserts and deletions (CSIs) in protein sequences provide an important category of molecular markers for understanding phylogenetic relationships. ... The CSIs that are restricted to a particular clade or group of species, generally provide good phylogenetic markers of common evolutionary descent slide 8 The family Enterobacteriaceae harbors many important pathogens, however it has proven difficult to reliably distinguish different members of this family or discern their interrelationships.  To understand the interrelationships among the Enterobacteriaceae species, we have constructed two comprehensive phylogenetic trees for 78 genome-sequenced Enterobacteriaceae species based on 2487 core genome proteins, and another set of 118 conserved proteins.  The genome sequences of Enterobacteriaceae species were also analyzed for genetic relatedness based on average amino acid identity and 16S rRNA sequence similarity.  In parallel, comparative genomic studies on protein sequences from the Enterobacteriaceae have identified 88 molecular markers in the form of conserved signature indels (CSIs) that are uniquely shared by specific members of the family. slide 10 identification of enterobacteriaceae biochemical reaction Oxidase test  All members of Enterobacteriaceae are oxidase negative  Pseudomonas is oxidase positive  O/F test  All members of Enterobacteriaceae are O+/F+  Pseudomonas is O+/F-  Nitrate reductase  All members of Enterobacteriaceae are nitrate reductase positive  Pseudomonas is nitrate reductase negative slide 11 identification of enterobacteriaceae Differentiation between LF & NLF by Growth Method: on MacConkey agar  MacConkey agar is inoculated with tested organism using streak plate technique  Incubate the plate in incubator at 37 C/24 hrs Results:  LF organism appears as pink colonies (e.g. E. coli)  NLF organism appears as colorless colonies (e.g. Shigella)

1. Classification of
Enterbacteriaceae

2. ENTEROBACTERIACEAE
1. Commonly present in large intestine •
2. Non sporing , non acid fast,
3. Gram – bacilli. •
4. A complex family of organisms, •
5. Some are non pathogenic •
6. A few are highly pathogenic, •
7. Some commensals turn out to be pathogenic as in uti after
catheterization.

3. Characterstics of Enterobacteriaceae •
1. All Enterobacteriaceae are
2. – Gram-negative rods
3. – Ferment glucose with acid production
4. – Reduce nitrates into nitrites
5. – Oxidase negative
6. Facultative anaerobic
7. Motile except Shigella and Klebsiella
8. Non-capsulated except Klebsiella
9. Non-fastidious
10. Grow on bile containing media (MacConkey agar)

7. Conserved signature inserts and
deletions (CSIs) in protein
sequences provide
an important category of
molecular markers for
understanding phylogenetic
relationships. ... The CSIs that are
restricted to a particular clade or
group of species, generally provide
good phylogenetic markers of
common evolutionary descent

8.  The family Enterobacteriaceae harbors many important pathogens, however it has
proven difficult to reliably distinguish different members of this family or discern their
interrelationships.
 To understand the interrelationships among the Enterobacteriaceae species, we have
constructed two comprehensive phylogenetic trees for 78 genome-
sequenced Enterobacteriaceae species based on 2487 core genome proteins, and
another set of 118 conserved proteins.
 The genome sequences of Enterobacteriaceae species were also analyzed for genetic
relatedness based on average amino acid identity and 16S rRNA sequence similarity.
 In parallel, comparative genomic studies on protein sequences from
the Enterobacteriaceae have identified 88 molecular markers in the form of conserved
signature indels (CSIs) that are uniquely shared by specific members of the family.

10. Identification of Enterobacteriaceae
Biochemical reactions
Oxidase test
All members of Enterobacteriaceae are oxidase negative
Pseudomonas is oxidase positive
O/F test
All members of Enterobacteriaceae are O+/F+
Pseudomonas is O+/F-
Nitrate reductase
All members of Enterobacteriaceae are nitrate reductase positive
Pseudomonas is nitrate reductase negative

11. Identification of
Enterobacteriaceae
Differentiation between LF & NLF by Growth
Method:
on MacConkey agar
MacConkey agar is inoculated with tested organism
using streak plate technique
Incubate the plate in incubator at 37 C/24 hrs
Results:
LF organism appears as pink colonies (e.g. E. coli)
NLF organism appears as colorless colonies (e.g.
Shigella)