Hemophilus

Lab Nineteen:- ______________ Medical Microbiology
Prepared by: Luma J. Witwit


Hemophilus

General characteristics:

Gram stain: pleomorphic, gram-negative rod to gram-negative coccobacilli. They require growth factors provided by blood: X and V factor.

X factor is heat stable tetrapyrrole compounds such as hemin or hemoglobin.

V factor is heat labile NAD (coenzyme I)or NADP (coenzyme II).

Both factors are found in blood, but need heat to break down RBCS and release factors, so chocolate agar is used for the recovery of Hemophilus.
Hemolysis should be checked on horse or rabbit blood agar.

Porphyrin test:

X-independent Hemophilus excrete prophyrins, (positive result its indicates that the organism dose not need factor X).

Hemophilus influenzae:

H.influenzae is found on the mucous membranes of the upper respiratory tract in human. Its an important causes of meningitis in children and occasionally causes respiratory tract infection in children and adult.

Specimens:

Specimens consist of nasopharyngeal swabs, blood, pus and spinal fluid for smears and cultures.

Culture:

On choclate agar ,flat,grayish-brown colonies with diameters of 1-2mm are present after 24 hours of incubation.


Disease:

H.influenzae causes flowing diseases:-

Pharyngitis, epiglottitis, otitis, sinusitis, bacteremia, meningitis, urethritis, maternal-neonatal infection.

Most H. influenzae Infection occur in children 1 month to 5 years old, the majority of systemic infections are caused by serotype b.

Hemophilus parainfluenzae causes Diseases: endocarditis, urethral, maternal-neonatal infections.

Hemophilus aegypticus causes conjunctivitis, Barzilian purpic fever.

Hemophilus ducreyi causes chancroid, a highly contagious sexually transmitted disease.
H. hemolyticus, H. parahemolyticus, H. aphrophilus,
H. paraphrophilus and H. segnis are mostly found as normal flora and rarely cause disease.