Scientific classification
Domain:Bacteria
Kingdom:Eubacteria
Phylum:Proteobacteria
Class:Gammaproteobacteria
Order:Pasteurellales
Family:Pasteurellaceae
Genus:Haemophilus
Species:H. influenzae
Medical important species
Haemophilus influenzae
 Haemophilus aegyptius
 Haemophilus ducreyi

Normal habitat
H.influenzae (mostly non-capsulated
strains), H. parainfluenzae and
H.aegyptius is normal flora of the upper
respiratory tract
 Infections causing:
1. Pyogenic meningitis
2. Acute epiglottitis
3. Cellulitis, middle ear infection,etc

conjuctivitis
Microscopy


Small, non-motile, Gram negative rods
or coccobacili
Long thread-like form in old csf culture
Microscopic observation
Culture of H.influenzae





H.influenzae grows better in aerobically
compare to anaerobically
The optimum temperature for growth 35 –
37oC
The are X and V factor
Both represent in blood agar and permit the
culture to grow
H.influenzae and H.aegyptius need X and V
factor, H. parainfluenzae need V factor and
H.ducreyi need X factor
Biochemical tests

Not usually used to identify hemophilus

6 biovars of H.influenzae are recognized
based on the indole, urease and
ornithine decarboxylase (ODC) reactions
of the diff strains
Serology
Consist of 1 – f serotypes
 Mostly causing meningitis belong to
serogroup b
 Most strains that cause chronic bronchial
disease are non-capsulated
Antimicrobial sensitivity
 Resistant towards chloramphenicol,
ampicilin, tetracycline, erythromycin and
cotrimoxazole
 H. ducreyi is sensitive to sulphonamides
 Ampicillin resistant are common

Staphylococcus aureus
Staphylococcus epidermidis
Staphylococcus saprophyticus
Scientific classification
Kingdom:Bacteria
Phylum:Firmicutes
Class:Bacilli
Order:Bacillales
Family:Staphylococcaceae
Genus:Staphylococcus
Introduction
Are microbial flora of the skin, upper
respiratory tract and intestinal tract
 S.aureus usually cause abscesses,
boils, conjuctivitis, pneumonia,
septicemia, food poisoning and scalded
skin syndrome
 S. epidermidis causing bactericaemia
 S. saprophyticus causing cystitis and
acute urethritis

Laboratory diagnosis
Microscopy
 Non-motile
 Non capsulate
 Gram positive cocci
 Arrangement single or in pair
 Size 1 µm diameter
Culture
Grow well in aerobically and also in
present of carbon dioxide
 Temperature between 10 – 420C,
optimum temperature are between 35 370C

S.aureus






Produce yellow to cream in blood and
chocolate agar (heated agar)
Occationally produce white 1-2 mm in
diameter colonies
Some strain produce beta-hemolytic when
grown aerobically
Colonies are slightly raised and easily
emulsified on a slide
Non- lactose fermenter in MacConkey agar
Mannitol salt agar is a useful differential
and selective agar to identify S.aureus
On blood agar
S.epidermidis


Colony is white
Non hemolytic in blood agar
S. saprophyticus
Maybe white or yellow
 There are non-hemolytic in BA
 Not grow anaerobically
 No growth in MacConkey agar

Biochemical reactions
S.aureus
 DNAse test will be positive for S.aureus but
negative in other species
 Catalase test will be positive in all
staphylococcus but negative in all
streptococcus
S. epidermidis and S. saprophyticus
 Coagulase negative
 DNAse negative
 Catalase positive
Antimicrobial sensitivity







Erythromycin
Clindamysin
Fucidin
Vancomycin
Many strains of S.aureus are penicillinresistant
S.epidermidis are more resistant than
S.aureus to antibiotics
S. saprophyticus less resistant to antibiotics
than S.aureus and S.epidermidis
Streptococcus pyogenes
Streptococcus agalactiae
Enterococci
Lecture content
Basic characteristics
 Classification
 Grouping of species
 Pathogenesis
 Lab diagnosis

Scientific classification







Kingdom – Bacteria
Phylum - Firmicutes
Class – Bacili
Order – Lactobacillales
Family – Streptococcaceae
Genus - Streptococcus
Species – 22 sp.
Basic characteristics





Gram-positive
Lactic acid bacteria group
Spherical
Grow in chain (twisted) or pairs
Mostly are facultative anaerobes
Habitat


Available in food such as
Emmentaler (Swiss) cheese
Normal flora of the mouth,
skin, intestine and upper
respiratory tract of humans
Classification
Beta
hemolysis
Alpha
hemolysis
• Lancerfield serotyping
• Based on
carbohydrates in the
bacterial cell wall
• Viridans groups
• S.pneumoniae
separated group
Alpha hemolysis
Surrounded
by an area of partial
haemolysis
Green-brown colour (reduced
haemoglobin)
Consist of pneumococci and
viridans group( alpha hemolytic
and no Lancerfield antigens
Pathogenicity
S.pyogenes (Group A)
Acute sore throat
 Scarlet fever
 Ear infections
 Peurperal sepsis
 Septicemia and occasionally endocarditis
 Skin infection such as celulitis and impetigo

Post-streptococcal disease
From the implication of pathogenesis, it will
leads to a serious stage of diseases:
 Acute glomerulonephritis
 Rheumatic fever
Enzymes & toxin production
By S. pyogenes
 Streptolysin O
 Streptolysin S
 Streptokinase (cause fibrinolysis)
 Hyarulonidase
 DNAses
 DPNAse
 Erythrogenic toxin
Other species
S.Agalactiae (Group B)
 Neonatal septicaemia, pneumoniae, meningitis
 Septic abortion and peurperal sepsis
Enterococci (Group D)
 Urinary tract infection
 Infections of ulcer and wounds
 Endocarditis and meningitis
Viridans
 Endocarditis
 Dental caries
 Brain abscess
Microscopy




Gram positive (purple)
Non-motile
Long chains
Sometimes in pair
Culture
Aerobically and anaerobically
Temperature between (22 – 42o C)
And enterococci are between (15 – 45o C)
On BA, colony usually less than 1 mm in
diameter
 Grey – white or colourless
 Dry / shiny, irregular outline
 Most of the pathogenic streptococcus
producing hemolysins




S. pyogenes
Produce beta hemolysis
Sensitive to bacitracin (can’t rely 100% to
it, coz not only group A sensitive to it) but
for viridans it is resistance towards
bacitracin
 A selective BA containing crystal violet was
suggested
 Does not grow in MacConkey agar


S.agalactiae
 Optochin
resistant but S.pneumoniae is
sensitive
 Beta hemolysis in BA
 In serum starch agar, it produces orange
pigment
Biochemical test
Species
Catalase
Bacitracin Optochin
Litmus
Milk
CAMP
S.pyogenes
-
+
-
-
-
S. agalactiae
-
-
-
-
+
Enterococci
-
-
-
+
-
Viridans
streptococci
-
-
-
-
-
Pneumococci
-
-
+
-
-