Hemophilus Flashcards
How bacteria are divided?
They are divided on the basis of the capsule and classified from A to F
Which type is the most important one in terms of disease production?
The Hib one
Where can we find them in the body normally?
In the respiratory tract in some people
Where are found the non-capsulated types? What do we call them? Why?
They are part of our normal flora in the respiratory tract or genital tract
They are called non-typable Haemophilus influenzae because they cannot be serotyped
How are H. Influenzae transmitted?
By respiratory secretions
By direct contact
What are virulence factors of the capsulated ones?
Polysaccharide capsule
LPS
Pili
Outer membranes
From what is composed the capsule?
From a polymer of ribosyl-ribitol-phosphate (RRP)
For what is responsible the LPS?
It is responsible for the CSF inflammation, and the sepsis in babies
It is responsible for damage of mucosal cells in respiratory tract, otitis media, sinusitis especially babies who can have 3 to 4 times a year an otitis media due to Haemophilus influenza mostly in addition to other bacteria.
Responsible for acute bronchitis
What is the function of the pili?
For colonization
Which diseases are caused by nontypeable ones?
Otitis media, sinusitis, pneumonia and bronchitis, meningitis
How test is done during otitis media?
It is done by tympanocentesis
Which test is done to detect sinusitis?
Culture of the sinus aspirate
Where bacteria can be detected in the case of pneumonia and bronchitis?
In the sputum. When it doesn’t contain enough specimen the right way is to take an aspirate from the stomach in the morning
In the blood. When it is positive in blood it means that pneumonia followed a bacteremia. It can be hematogenously or lymphogenously
How meningitis is caused?
It is directly spread from the throat not following a bacteremia
What are the diseases caused by the Hib type?
Meningitis, conjunctivitis, cellulitis, epiglottitis, septic arthritis
How meningitis is caused? Where bacteria can be detected in this case?
It is the result of a hematogenous spread
Bacteria can be found in the CSF or the blood if it was a hematogenous spread
How conjunctivitis is caused?
It is a local type of infection or a contamination in someway but not via the blood this is why bacteria couldn’t be found in the blood
Where the bacteria is found in the case of conjunctivitis?
It is found in the eye and rarely in the blood
How cellulitis is caused? Where bacteria is found in this case?
It results from a spread via the blood, bacteria is found in the skin or in the blood
What are the symptoms of epiglottitis?
High fever, hoarseness which is typical to epiglottitis, pain, dysphasia meaning difficulty in swallowing
How a specimen is taken?
Tracheostomy is done to open an airway for ventilation and then a specimen is taken
Why it is very dangerous to take a specimen from the epiglottis?
Where bacteria can be found?
Because we will have laryngospasm similar to that caused by diphtheria
Bacteria can be found in the blood
How septic arthritis is caused? Where bacteria can be found in this case?
it is caused by a spread via the blood
Bacteria can be found in the synovial fluid or in the blood
What is the best medium for their growth?
chocolate agar
Which growth factors are needed by H. influenza?
X factor (hemin) and V factor (NAD)
Which Haemophilus species only need the V factor?
Haemophilus parainfluenza
Which Haemophilus species only need the X factor?
Haemophilus ducreyi
Which bacteria can supply the NAD?
Where we can see the growth of Haemophilus influenzae in this case?
What do we call this phenomenon?
Staphylococcus aureus which are grown on a blood agar plate
Around the strip of staphylococcus aureus, we can see growth of Haemophilus influenza
This is called satellite phenomenon
Which antibiotics are given for meningitis?
Third generation cephalosporin continued for 1 to 2 weeks even if symptoms subside
What prophylaxis is given to protect the household contact?
rifampicin given orally once daily for 4 days
What is the vaccine? How it is given?
It is composed from the Hib polyribosyl-ribitol phosphate (PRP) capsule conjugated to diphtheria toxoid or tetanus toxoid
It is given at 2 months of age, another one between 2 and 6 months, and a booster at 12 to 15 months.
What’s the purpose of conjugation in this vaccine?
To increase the activity of the PRP
How Haemophilus ducreyi is transmitted?
Sexually transmitted
It has been considered a co-factor of HIV transmission i.e. it enhances transmission of HIV
What develops at the beginning of an infection?
A papule which contains PMN, edema, and disruption of epithelium cells
What happens to the papule then?
The papule will rupture forming a sharply defined ulcer called a chancroid ulcer
What is the structure of this ulcer?
Its base isn’t indurated, it is granulomatous, it bleeds easily and is extremely painful
What characterizes chancroid ulcers?
Infiltrates of macrophages, CD4 and CD8 lymphocytes which are important for HIV
Where bacteria can spread from ulcers? What does it cause?
To lymph nodes causing a painful unilateral inguinal lymphadenopathy that may rupture spontaneously to form inguinal ulcers
When there is bacteremia?
Only in AIDS patient
Does it give a permanent immunity? Is there any vaccine?
No permanent immunity
No vaccine
Which antibiotics are given?
Ceftriaxone
Erythromycin
Ciprofloxacin
