Chapter 10: Haemophilus, Bordetella, and Legionella
Terms
undefined, object
copy deck
- What do Haemophilus, Bordetella, and Legionella have in common?
- Gram (-) rods, all acquired through the respiratory tract
- What are two important factors in how H.flu causes disease?
- Polysaccharide capsule confers virulence. Antibodies to the capsule are lacking in infants and children between 6 months and 3 years of age.
- List the diseases that can be caused by H. influenza type b (Hib)?
-
Meningitis
Acute epiglottitis
Septic arthritis
Sepsis - What is the problem with treating Hib meningitis with antibiotics? Solution?
- The release of cellular antigens (like endotoxin) from lysed bacteria results in a violent immune response that can further destroy neurons. Potential solution is treatment with steroids 20 minutes prior to antibx
- What are the drugs of choice for serious Hib infections? For less serious infections?
-
3rd generation cephalosporins.
Ampicillin or amoxicillin. - Which species causes the STD chancroid? Clinical syx?
- Haemophilus ducreyi. Painful genital ulcer, unilateral painful swollen inguinal lymph nodes in 50%
- What is the diff dx for genital ulcers?
-
1) Syphilis
2) Herpes
3) Lymphogranuloma venereum (Chlamydia)
4) Haemophilus ducreyi - How is chancroid treated?
- Erythromycin or trimethoprim/sulfamethoxazole
- What organism causes whooping cough? Where do you see the majority of these cases today?
- Bordetella pertussis. Unimmunized infants younger than 1 year and young adults, because the vaccine only provides protection for about 15 years.
- List the stages of disease with Bordetella pertussis?
-
1. 1-week incubation
2. Catarrhal stage ( similar to an upper respiratory tract infection)
3. Paroxysmal stage (Bursts of nonproductive cough, inspiratory gasp, vomiting)
4. Convalescent stage - Describe the WBC profile of whooping cough?
- High lymphocytes, only moderate increase in neuts. (looks more like a viral picture)
- Describe treatment, prophylaxis for whooping cough?
- Primarily supportive. Erythromycin may prevent disease in the early stages. DPT vaccination is effective.
- Describe Legionella pneumophila? How does it cause infection?
- Aerobic gram-negative rod, ubiquitous in water environments. Aerosolized contaminated water is inhaled. Facultative intraceelular parasite that settles in the lower respiratory tract.
- What diseases can Legionella cause?
-
1. Asymptomatic infection
2. Pontiac fever
3. Legionnaires' disease - Pontiac fever has a clinical profile similar to...?
- Influenza
- Describe Legionnaires' disease?
- High fevers, severe pneumonia. One of the most common causes of community acquired pneumonia, but rarely diagnosed correctly.
- What are the risk groups for Legionnaires' disease? Treatment?
- Patients over 50 who are smokers or whose sputum gram stain reveals neutrophils and very few organisms (Legionella is really small). Treat with erythromycin.