Haemophilus spp. are small, pleomorphic, nonmotile, nonsporing Gram-negative rods or coccobacilli. They are aerobic and facultatively anaerobic. Growth is often enhanced by the addition of 5–10% carbon dioxide to the incubation atmosphere.

How does Haemophilus influenzae grow?

H. influenzae is a fastidious organism which grows best at 35-37°C with ~5% CO₂ (or in a candle-jar) and requires hemin (X factor) and nicotinamide-adenine-dinucleotide (NAD, also known as V factor) for growth. The standard medium used for growth of H.

Is Haemophilus influenzae obligate anaerobe?

Haemophilus influenzae is a facultative anaerobe that has an absolute requirement for NAD (factor V) and a source of haem (factor X). It was first described by Pfeiffer, during the influenza pandemic of 1889–1892.

Why does Haemophilus not grow on blood agar?

Members of the genus Haemophilus will not grow on blood agar plates, as all species require at least one of these blood factors for growth: hemin (X-factor) and/or nicotinamide adenine dinucleotide (V-factor).

Does Haemophilus grow on nutrient agar?

Haemophilus influenzae requires both factors X and V; accordingly, it grows on chocolate agar but not on blood agar (Fig. 30-2), although it may appear on a blood agar plate as tiny satellite colonies around the colonies of other bacteria that have lysed red blood cells.

Haemophilus influenzae - causes, symptoms, diagnosis, treatment, pathology

25 related questions found

Is Haemophilus aerobic?

Haemophilus spp. are small, pleomorphic, nonmotile, nonsporing Gram-negative rods or coccobacilli. They are aerobic and facultatively anaerobic. Growth is often enhanced by the addition of 5–10% carbon dioxide to the incubation atmosphere.

Does Neisseria meningitidis grow on blood agar?

N. meningitidis is a fastidious organism, which grows best at 35-37°C with ~5% CO₂ (or in a candle-jar). It can grow on both a blood agar plate (BAP) and a chocolate agar plate (CAP).

Is Haemophilus Ducreyi aerobic or anaerobic?

CHARACTERISTICS: The agent is a fastidious facultative anaerobic (7), gram negative, non spore-forming, cocobaccillus (8). It is 1.5 µm long and 0.5 µm wide (2). In exudates, H. ducreyi is typically seen in a railroad or chaining arrangement (9).

Does Staphylococcus aureus grow on chocolate agar?

Staph. aureus will grow on general culture media such as Blood Agar and chocolated Blood Agar and therefore can be isolated from direct plating of clinical specimens. More specialised media, such as Staph/Strep Selective Medium contain antimicrobials.

What bacteria only grows on chocolate agar?

Chocolate agar is used for growing fastidious respiratory bacteria, such as Haemophilus influenzae and Neisseria meningitidis.

What is the morphology of Haemophilus influenzae?

Microscopic morphology of Haemophilus influenzae. Haemophilus influenzae is a nonmotile, Gram-negative, rod-shaped bacterium. The rounded ends of short (0.5-1.5 μm) bacilli make many appear round, hence the term coccobacilli.

Is Haemophilus influenzae encapsulated?

H. influenzae may be either encapsulated (typeable) or unencapsulated (nontypeable). There are 6 encapsulated serotypes (designated a through f) that have distinct capsular polysaccharides.

Where is Haemophilus Aegyptius most likely found?

H. aegyptius is normally found living in human epithelial cell linings [1], where it exhibits colonization and adherence to epithelial cells with large clusters of elongated chains of cells [2]. As a biogroup, H. influenzae biogroup aegyptius has traits that differ from Haemophilus influenzae (H.

What is the difference between Haemophilus Parainfluenzae and Haemophilus influenzae?

Haemophilus parainfluenzae is a common isolate from the nasopharynx. It has different colony morphology from H. influenzae and can be distinguished biochemically by the ability to produce acid from mannose. Its role in human disease is unclear.

Is Haemophilus influenzae rod shaped?

Haemophilus influenzae are small, gram-negative, rod-shaped bacteria. Because of their special growth requirements, they do not grow on usual blood agar media, but flourish on the mucosal membranes of the human respiratory tract where they adhere to the epithelial cells by fimbriae (a potential vaccine component).

Can Neisseria gonorrhoeae grow on MacConkey agar?

Neisseria gonorrhoeae is: fastidious, Gram-positive diplococcus. fastidious, Gram-negative bacterium. fastidious, Gram-negative bacterium (grows in lactose-negative colonies on MacConkey agar)

Is blood agar selective or differential media?

Blood agar is differential media because 3 different types of hemolysis, or lysing of red blood cells, can be seen on this plate. ... When combined with patient history and colony morphology, hemolysis observed on blood agar can help microbiologists make a presumptive organism identification.

Can staph aureus grow on MacConkey agar?

MacConkey agar selects for organisms like Escherichia coli (Gram negative bacilli) while inhibiting the growth of organisms like Staphylococcus aureus (Gram positive cocci).

Is Haemophilus Ducreyi motile?

Haemophilus ducreyi is a gram-negative, rod-shaped, facultatively anaerobic, non-motile, pathogenic bacillus (Trees and Morse, 1995).

Is chancroid a STD?

Chancroid is a bacterial sexually transmitted disease (STD) caused by infection with Haemophilus ducreyi. It is characterized by painful necrotizing genital ulcers that may be accompanied by inguinal lymphadenopathy. It is a highly contagious but curable disease.

Can Haemophilus Ducreyi be cultured?

H. ducreyi can be cultured on chocolate agar. It is best treated with a macrolide, e.g. azithromycin, and a third-generation cephalosporin, e.g. ceftriaxone.

Is Neisseria aerobic or anaerobic?

The human pathogen Neisseria meningitidis is the major causative agent of bacterial meningitis. The organism is usually treated as a strict aerobe and is cultured under fully aerobic conditions in the laboratory.

Is Neisseria meningitidis aerobic or anaerobic?

The human pathogen Neisseria meningitidis is the major causative agent of bacterial meningitis. The organism is usually treated as a strict aerobe and is cultured under fully aerobic conditions in the laboratory.

Does Neisseria gonorrhoeae grow on blood agar?

Gonococci are not able to grow on common blood agar. ... agar is used for growing fastidious respiratory bacteria, such as Haemophilus influenzae and Neisseria meningitidis.