prof . dr. ihsan edan alsaimary department of microbiology - college of medicine - university of basrah - basrah -IRAQ ihsanalsaimary@gmail.com 00964 7801410838

1. Escherichia coli , Klebsiella ,
Enterobacter, Serratia , Hafnia , Proteus,
Providencia,citrobacter and Morganella
1
Prof dr. Ihsan Edan Alsaimary
department of microbiology – college of medicine – university of basrah - e.mail :
ihsanalsaimary@gmail.com

2. Escherichia coli
• Morphology Gram - ve Straight rods,
• 1-3 X 0.4 -0.7 microns,
• Appear in singles or in pairs,
• Motile by peritrichate flagella.
• Very few strains non motile
• Not spore forming, Non acid fast.
Detection of E.coli in water indicates
pollution and contamination. 2

3. E.coli
Cultural characters
• Aerobic / Facultative Anaerobic
• Grows between 10 – 40 c optimal at 37 c
• Grown in simple medium
• Produce Large grayish ,Thick white , moist
smooth opaque colonies
• On MacConkey medium Produce Bright
pink Lactose fermenters.
• Many pathogenic strains are haemolytic
on blood agar. 3

4. E.coli
Biochemical Characters,
•Glucose,Lactose,Mannitol,Maltose
fermented. with A/G
Indole +
Methyl Red +
Voges Proskauer – I,M,Vi,C tests.
Citrate –
Urease not produced.
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5. E.coli
Antigenic Structure
• Somatic O 170
• Capsular K 100
• Flagella H 75
• Virulence factors
Surface Antigens Toxins
O Endotoxic activity
K protects against the phagocytosis
Fimbriae promote virulence ( important in UTI )
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6. Virulence Factors
• Two types of virulence factors in E.coli
• Surface antigens (O,K,H) and Toxins
• .FimbriaePresent in large numbers causing
mannose sensitive Haemagglutination
• Colonisation factor antigens in enterotoxigenic
E.coli
• E.coli produce Exotoxins
• Hemolysins, Enterotoxins causes Diarrheas,
• Important toxins produces.
• Heat labile HL (toxin like Cholera toxin)
• Heat stable HS Vero toxins VT (Like Shigella toxins)6

7. Toxins of E.coli
• L T contains component A and B
• A = Active B= Binding
• B causes Binding with Gm I Ganglioside
receptor on Intestinal epithelial cells
• ST A and ST B
• ST A Acts by activation of Cyclic guanosine
monophosphate.( C GMP )
• Causes fluid accumulation in Intestine.
• E.coli ( Some ) produce Verocytotoxin
causes cytotoxicity to Vero cells.
• Acts like Shigella dysentery toxin 7

9. E. coli infections
• Neonatal meningitis – is the leading cause
of neonatal meningitis and septicemia
with a high mortality rate.
– Usually caused by strains with the K1
capsular antigen.
• Gastroenteritis – there are several distinct
types of E. coli that are involved in
different types of gastroenteritis:
– enterotoxigenic E. coli (ETEC),
– enteroinvasive E. coli (EIEC),
– enteropathogenic E. coli (EPEC) ,
– enteroaggregative E. coli (EAEC), and
– enterohemorrhagic E. coli (EHEC).
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10. 1-Enteropathogenic E.coli
• Causes diarrheal disease in children,
• EPEC O26/O11
• Produce Verocytotoxin
• Infantile enteritis, Involves upper part of
Intestine
• Brush border of the intestine is lost
• Intimacin – EPEC adhesion factor
• . Fimbrial colonization factor antigens
• Frequent in summer months
• Poor hygiene predisposes.
• Out breaks in Institutions 10

11. 2-Enterotoxigenic E.coli
• Common and causes endemics in developing countries in
all age groups
• May be mild watery diarrhoea to fatal conditions
• Produce Heat stable /Heat labile toxins
• Adheres to epithelium of small intestine.
• Present with Nausea, Vomiting and Lose stool
• H L like cholera toxin
• Causes accumulation of fluids
• Adhesive factors Fimbrial colonization factor antigens
Fimbriae specific receptor in the intestinal epithelium
CFA
Mortality in children < 5 years
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12. ETEC• Causes travelers diarrhea
• Water contaminated with Human and Animal feces
predisposes.
• Laboratory Diagnosis
Demonstration of Enterotoxin LT and ST
Tissue culture tests,
ELISA
Passive agglutination tests.
Animal experiments in Rabbit ileal loop test.
Treatment and prevention
• Doxycycline, Trimethoprim, Norfloxacillin Fluroquinolones
• Avoid contaminated food, Safe protected water ,prefer bottled
water, Hot foods, Hot Drinks, Boiled milk
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13. 3-Enteroinvasive E.coli
• Resembles Shigella in many respects
• Non lactose fermenter and non motile
• They invade the intestinal epithelium
• Penetrate HeLa cells in tissue culture
• May produce mild diarrhoea to frank
dysentery
• Diagnosis
• Sereny test positive animal Rabbit.
• ELISA 13

14. 4-Enterohemorrhagic E.coli
• Produce Verocytotoxin or shiga like toxin
• Mild diarrhea - can be fatal hemorrhagic colitis.
and uremic syndrome.
• Present in Human and Animal feces.
• Hemorrhagic complication with O157:H7 in
Japan and USA.
• Salads vegetables, Radish Proper cooking
• The disease may manifest as food poisoning
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15. Dr.T.V.Rao MD 152/14/2020

16. DIAGNOSIS OF EHEC
• Bacterial Culturing
• DNA detection methods.
• Cytotoxic effects on Vero
cells.
• Detection with
monovalent sera O157/H716

17. 5-Enteroaggresive E.coli
• They appear aggregated in s stacked
brick formation Hep-2 cell
• They produce persistent diarrheal
• They produce weight heat stable
enterotoxin called as low molecular
heat stable enterotoxin
• diagnosis of EAEC
• Stool Culture methods
• Detection of Enterotoxin 17

18. 2/14/2020 Dr.T.V.Rao MD 18

19. Culturing for E.coli
• Mid stream sample/semi quantitative
culturing (Kass et al ) >_ 1.00,000/ml of
urine. ( significant Bacteriuria )
• Urine should not be kept in wards for > 2
hours and to be preserved at 4 c
• Culture by standard loop method.
• Fixed volume cultured on MacConkey
agar Lactose fermenters I M Vi C
• Antibiotic sensitivity tested.
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20. Klebsiella species
• It is named after the German microbiologist Edwin Kleb's
(1834–1913). Frequent human pathogens,
• Klebsiella organisms can lead to a wide range of disease
states, notably pneumonia, urinary tract infections,
septicaemia, and soft tissue infections.
• Usually found in GI tract
• seven major species with demonstrated similarities in DNA
homology are known. These are (1) Klebsiella pneumoniae,
(2) Klebsiella ozaenae, (3) Klebsiella rhinoscleromatis, (4)
Klebsiella oxytoca, (5) Klebsiella planticola, (6) Klebsiella
terrigena, and (7) Klebsiella ornithinolytica
• K. pneumoniae is mostly commonly isolated species
• Possesses a polysaccharide capsule, which protects
against phagocytosis and antibiotics AND makes the
colonies moist and mucoid ,Has a distinctive “yeasty” odor
• Frequent cause of nosocomial pneumonia 20

21. Klebsiella
• Klebsiella
– NF of GI tract, but potential pathogen in other
areas
– TSI A/A + gas , LIA K/K , Urea + , Citrate +
– MR-, VP+ , Motility - Has both O and K antigens
– Virulence factors
• Capsule , Adhesions , Iron capturing ability
– Clinical significance
• Causes pneumonia, mostly in immunocompromised
hosts.
• A major cause of nosocomial infections such as
septicemia and meningitis
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22. Enterobacter species
• Comprised of 12 species; E. cloacae
and E. aerogenes are most common
• Isolated from wounds, urine, blood
and CSF
• Major characteristics
– Colonies resemble Klebsiella
– Motile
– MR negative; VP positive
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23. Serratia species
• Seven species, but S. marcescens is the
only one clinically important
• Frequently found in nosocomial infections
of urinary or respiratory tracts
• Implicated in bacteremic outbreaks in
nurseries, cardiac surgery, and burn units
• Fairly resistant to antibiotics
• Produce characteristic pink pigment, especially
when cultures are left at room temperature
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24. Hafnia species
• Hafnia alvei is only species
• Has been isolated from many
anatomical sites in humans and
the environment
• Occasionally isolated from stools
• Delayed citrate reaction is major
characteristic
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25. Other Enterobacteriaceae
• Proteus, Providencia, and Morganella
– Are all part of the NF of the GI tract (except
Providencia). All are lactose negative
– All motile, with Proteus swarming
– Phenyl alanin +
– Lysine deamination +
– Urea + for most, strongly + for Proteus
– TSI variable (know the reactions for each
in the lab!)
– Indole – only P. mirabilis is -
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26. Proteus species• P. mirabilis and P. vulgaris are widely recognized
human pathogens
• Isolated from urine, wounds, and ear and
bacteremic infections
• Both produce swarming colonies on non-selective
media and have a distinctive “burned chocolate”
odor
• Both are strongly urease positive
• Both are phenylalanine deaminase positive
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27. Morganella species
• Morganella morganii is only
species
• Documented cause of UTI
• Isolated from other anatomical
sites
• Urease positive
• Phenylalanine deaminase positive27

28. Providencia species
• Providencia rettgeri is pathogen of
urinary tract and has caused
nosocomial outbreaks
• Providenicia stuartii can cause
nosocomial outbreaks in burn units and
has been isolated from urine
• Both are phenylalanine deaminase
positive
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29. Citrobacter species
• Citrobacter freundii associated
with nosocomial infections (UTI,
pneumonias, and intraabdominal
abscesses)
• Ferments lactose and hydrolyzes
urea slowly
• Resembles Salmonella sp.
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