1. Klebsiella- Enterobacter- Serratia Group
@ Gram negative rods, non-motile, aerobic
and facultatively anaerobic
@ Catalase positive, oxidase negative,
@ Attacks sugars fermentatively, usually
with gas production
@ KCN positive, VP positive
@ Ornithine decarboxylase negative,
@ Urease positive, phenylalanine negative.

3. Enterobacter:
@ Gram negative rods, motile, aerobic and
facultatively anaerobic
@ Catalase positive, oxidase negative
@ Attacks sugars fermentatively, gas is
produced
@ VP positive, gluconate positive, gelatin
liquefied slowly
@ Ornithine decarboxylase positive.

5. Serratia:
@ Gram negative rods, motile, aerobic and
facultatively anaerobic
@ Catalase positive, oxidase negative,
@ Attack sugars fermentatively, often with
gas production
@ VP usually positive, gluconate positive,
ornithine decarboxylase positive,
@ Deoxyribonuclease positive,
@ Produce a red pigment .

7. Differences of the Group
Character
Klebsiella
Enterobacter
Serratia
Motility - +
Indole
Red pigment
Quellung reaction

9. Klebsiella: a) K. pneumoniae . b) K. rhinoscleromatis. c) K. ozaenae.
SPECIES:
Klebsiella: a) K. pneumoniae .
b) K. rhinoscleromatis.
c) K. ozaenae.
Enterobacter: a) E. cloacae.
b) E. aerogenes.
Serratia: S. Marcescens
Edwin Klebs ( ) – Described Klebsiella

11. PATHOGENICITY:
@ All three organisms produce an
endotoxin that leads to septic shock.
@ K. pneumoniae produces a large
capsule that has an antiphagocytic
action.
@ Enterobacter and Serratia are
opportunistic organisms.

13. Epidemiology:
@ Predisposing factors to Klebsiella
infection are: old age, respiratory
disease, diabetes, and alcoholism.
@ Klebsiella carrier rate in the respiratory
tract is 10% of normal people.
@ Enterobacter and Serratia infections
occur following catheterization,
intubation, & urinary tract procedures.
@ Serratia infection outbreaks occur after
using contaminated water in respirators

15. Clinical findings:
@ Infections produced by all members of
the group are UTI, pneumonia,
bacteraemia, and meningitis.
@ K. pneumoniae causes pneumonia with
a thick, bloody sputum that progresses
to necrosis and abscess formation.
@ K. ozaenae, causes atrophic rhinitis.
@ K. rhinoscleromatis, causes destructive
granuloma of nose & pharynx

17. LABORATORY DIAGNOSIS:
Specimens collected:
@ Urine, sputum, pus, infected tissue.
Microscopy:
@ Gram negative rods:
a) Klebsiella is non-motile, has a big
capsule.
b) Enterobacter and Serratia are motile,
and non-capsulated.

19. Culture:
@ Media are Mac Conkey, blood agar.
@ Klebsiella produces mucoid colonies,
and lactose fermenters.
@ Enterobacter gives similar colonies as
Klebsiella, but not so mucoid.
@ Serratia are non-lactose fermenters.
Produces red pigment when grown on
nutrient agar at room temperature.

21. Biochemical reactions:
@ Members of the group are similar in most
biochemical reactions.
@ They are differentiated by motility, indole,
pigment production, & quellung reaction.
Antisera:
@ Pooled antisera to detect monovalent
specific O and K antigens by slide
agglutination.

23. Prevention
@ Some hospital-acquired infections
caused by these rods are prevented by
general measures such as:
# Changing the site of intravenous
catheters
# Removing urinary catheters when they
are no longer needed
# Proper care of respiratory devices.
@ There is no vaccine.

25. TREATMENT
@ This depends on the site of disease and
the resistance pattern of the isolate:
# For hospital-acquired infections give
empirically cefotaxime or gentamicin until
sensitivity tests are back.
# In severe Enterobacter infections, a
combination of gentamicin and imipenem
may be given.