Bordetella pertussis
From Wikipedia, the free encyclopedia
| Bordetella pertussis | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
 |
||||||||||||||
| Scientific classification | ||||||||||||||
|
||||||||||||||
| Binomial name | ||||||||||||||
| Bordetella pertussis (Bergey et al. 1923) Moreno-López 1952 |
Bordetella pertussis is a Gram-negative, aerobic coccobacillus of the genus Bordetella, and the causative agent of pertussis or whooping cough. Unlike B. bronchiseptica, B. pertussis is non-motile.
There does not appear to be a zoonotic reservoir for B. pertussis—humans are its only host.
The bacterium is spread by coughing and by nasal drops. The incubation period is 7-14 days.
Contents |
[edit] Pertussis
Pertussis (or Whooping Cough), is an infection of the respiratory system and characterized by a “whooping” sound when the person breathes in. In the US it killed 5,000 to 10,000 people per year before a vaccine was available. Vaccination has transformed this and between 1985-88 fewer than 100 children died from pertussis. Worldwide in 2000, according to the WHO, around 39 million people were infected annually and about 297,000 died. A graph is available showing the dramatic effect of introducing vaccination in England.
The infection occurs most with children under the age of one when they are immunized or children with faded immunity, normally around the age 11 through 18. The signs and symptoms are similar to a common cold: runny nose, sneezing, mild cough, and low-grade fever. After a spell, they might make a “whooping” sound when breathing in or vomit. Adults have milder symptoms, like prolonged coughing without the “whoop.” The patient becomes most contagious during the catarrhal stage of infection, normally 2 weeks after the coughing begins. It may become airborne when the person coughs, sneezes, or laughs. Pertussis vaccine is part of the DTaP (diphtheria, tetanus, acellular pertussis) immunization. The paroxysmal cough precedes a crowing inspiratory sound characteristic of pertussis. (Infants less than 6 months may not have the typical whoop.) A coughing spell may last a minute or more, producing cyanosis, apnoea and seizures. A prolonged cough may be irritating and sometimes a disabling cough may go undiagnosed in adults for many months.
Bordetella pertussis also produces a lymphocytosis-promoting factor, which causes a decrease in the entry of lymphocytes into lymph nodes. This can lead to a condition known as lymphocytosis, with a complete lymphocyte count over of 4000/μL in adults or over 8000/μL in children.
[edit] Diagnosis
A nasopharyngeal swab is sent to the bacteriology laboratory for Gram stain (Gram negative, coccobacilli, no arrangement), growth on Bordet-Gengou agar or BCYE plate with added cephalosporin to select for the organism, which shows mercury-drop colonies.
The organism is oxidase positive, but urease, nitrase, and citrate negative. It is also non-motile.
[edit] References
- Ryan KJ; Ray CG (editors) (2004). Sherris Medical Microbiology, 4th ed., McGraw Hill. ISBN 0-8385-8529-9.
[edit] External links
- Pertussis Information from the World Health Organisation
- Bordetella chapter in Baron's Medical Microbiology (online text at the NCBI bookshelf).
- Bordetella pertussis in ARUP Consult — The Physician's Guide to Laboratory Test Selection and Interpretation
- Pertussis United Kingdom Health Protection Agency.
 |
This Proteobacteria-related article is a stub. You can help Wikipedia by expanding it. |
