M.Muazzam SheriffLecturer Microbiology & ImmunologyIbn Sina National College for Medical Studies

Bacillus Common Species: Bacillus anthracis Bacillus cereus

Microscopic Morphology• Gram Positive Bacilli

Bacillus Species

Gram Positive Bacilli

Bacillus anthracis endospores stained with Malachite Green

Clostridium Genus Clostridium consists of Gram positive, anaerobic, spore forming bacilli.

Common Species Clostridium perfringens Clostridium botulinum Clostridium tetani Clostridium dificile

Microscopic Morphology

Gram Positive Bacilli

Clostridium perfringens

Clostridium tetani

Gram positive bacilli with drum stick appearance

Anaerobic Jar and Gas Pack Produces anaerobic conditions for strict anaerobe

Anaerobic jar converts Oxygen to water by chemical reaction. Water is added to the red envelope to generate hydrogen gas (H2) and carbon dioxide.

The resulting hydrogen combines at the palladium catalyst in the jar lid to convert the oxygen present into water, creating the anaerobic environment

Anaerobic Jar

Gas Pack

Corynebacterium

Common species Corynebacterium diphtheriae

Microscopic morphology• Gram Positive Bacilli with Palisade arrangement (X

or Y shaped arrangement) (Chinese lettering)

Corynebacterium diphtheriae

Palisade arrangement

Enterobacteriaciae

 Small Gram-negative non-spore forming enteric bacilli (also called coccobacilli)

Common species Escherichia coli Klebsiella pneumoniae   Proteus vulgaris.

Enterobacteriaciae species

e

Growth of Escherichia coli on Mac Conkey Agar Plate

Pink Lactose fermenting colonies

Growth of Klebsiella pneumoniae on Mac Conkey Agar Plate

Lactose Fermenting- Pink mucoid colonies

Growth of Proteus mirabilis on Sterile Blood agar plate

Swarming Growth

Pseudomonas Species.Common species Pseudomonas aeroginosa

Microscopic morphology• Gram negative short Bacilli

Growth of Pseudomonas on MacConkey Agar Plate

Non-Lactose fermenting colonies with green pigmentation

Oxidase Test

A.Pseudomonas aeroginosa - Purple color indicates positive.

B. Escherichia coli - No colour change indicates Negative.

N-Tetramethyl-p- phenylenediamine (TMPD) or,N-Dimethyl-p-phenylenediamine (DMPD), which is also a redox indicator. The reagent is a dark blue to violet color when oxidized, and colorless when reduced.

Haemophilus speciesHaemophilus genus represents a large group

of Gram-negative rods (pleomorphic)

Common species Haemophilus influenzae

Growth of Haemophilus influenzae on Chocolate agar

forms moist, smooth colonies.

Chocolate agar (enriched medium) is a non-selective medium for the primary isolation of fastidious bacteria.

Example: Neisseria meningitidis and Haemophilus spp.

Chocolate agar contains haemoglobin solution and supplemental ingredients that are required by some fastidious organisms.

*Factors X (hemin) and V (Nicotinamide Adenine Dinucleotide [NAD]) are present