BORDETELLA PERTUSSIS is a Gram-negative , aerobic , pathogenic , encapsulated coccobacillus of the genus Bordetella , and the causative agent of pertussis or whooping cough. Unlike B. bronchiseptica , B. pertussis is not motile . Its virulence factors include pertussis toxin , filamentous hæmagglutinin , pertactin , fimbria , and tracheal cytotoxin .
The bacterium is spread by airborne droplets; its incubation period is 9–10 days on average (range 6–20 days). Humans are the only known reservoir for B. pertussis. The complete B. pertussis genome of 4,086,186 base pairs was published in 2003.
* 1 Pertussis * 2 B. pertussis as a zoonotic disease * 3 Diagnosis * 4 References * 5 External links
Main article: Pertussis
Pertussis is an infection of the respiratory system characterized by a “whooping” sound when the person breathes in. In the US, it killed between 10,000 and 20,000 people per year before a vaccine was available. Vaccination has transformed this; between 1985 and 1988, 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. B. pertussis infects its host by colonizing lung epithelial cells. The bacterium contains a surface protein, filamentous haemagglutinin adhesin , which binds to the sulfatides found on cilia of epithelial cells. Once anchored, the bacterium produces tracheal cytotoxin , which stops the cilia from beating. This prevents the cilia from clearing debris from the lungs, so the body responds by sending the host into a coughing fit. These coughs expel some bacteria into the air, which are free to infect other hosts.
B. pertussis has the ability to inhibit the function of the host's immune system. The toxin, known as pertussis toxin (or PTx), inhibits G protein coupling that regulates an adenylate cyclase -mediated conversion of ATP to cyclic AMP . The end result is phagocytes convert too much ATP to cyclic AMP, which can cause disturbances in cellular signaling mechanisms, and prevent phagocytes from correctly responding to an infection. PTx, formerly known as lymphocytosis-promoting factor, causes a decrease in the entry of lymphocytes into lymph nodes, which can lead to a condition known as lymphocytosis , with a complete lymphocyte count of over 4000/μl in adults or over 8000/μl in children. This is unique in that many bacterial infections illustrate neutrophil-predominance instead.
The infection occurs mostly in children under the age of one when they are unimmunized , or children with faded immunity , normally around the ages 11 through 18. The signs and symptoms are similar to a common cold : runny nose, sneezing , mild cough , and low-grade fever . The patient becomes most contagious during the catarrhal stage of infection, normally two weeks after the coughing begins. It may become airborne when the person coughs, sneezes, or laughs. Pertussis vaccine is part of the diphtheria , tetanus , and acellular pertussis (DTaP) immunization. The paroxysmal cough precedes a crowing inspiratory sound characteristic of pertussis. After a spell, the patient might make a “whooping” sound when breathing in, or may vomit. Adults have milder symptoms, such as prolonged coughing without the “whoop”. Infants less than six months also may not have the typical whoop. A coughing spell may last a minute or more, producing cyanosis , apnoea , and seizures . However, when not in a coughing fit, the patient does not experience trouble breathing. This is because B. pertussis inhibits the immune response, so very little mucus is generated in the lungs.
A prolonged cough may be irritating and sometimes a disabling cough may go undiagnosed in adults for many months.
B. PERTUSSIS AS A ZOONOTIC DISEASE
Uncertainties of B. pertussis and whooping cough as a zoonotic disease have existed since around 1910, but in the 1930s, the bacteria were found to have lost their virulent power when repeatedly spread on agar media. This explained the difficulties in reproducing results from different studies, as the preinoculating handling of the bacteria were not standardized among scientists.
At least some primate species are highly sensitive to B. pertussis, and develop a clinical whooping cough in high incidence when exposed to low inoculation doses. Whether the bacteria spread naturally in wild animal populations is not satisfactory confirmed by laboratory diagnosis, but whooping cough has been found among wild gorillas. Several zoos have learned to vaccinate their primates against whooping cough.
A nasopharyngeal or an oropharynx swab is sent to the bacteriology laboratory for Gram stain (Gram-negative, coccobacilli, diplococci arrangement), growth on Bordet-Gengou agar or BCYE plate with added cephalosporin to select for the organism, which shows mercury drop-like colonies. B. pertussis can also be detected by PCR, which is more sensitive than culture. The primers used for PCR usually target the transposable elements IS481 and IS1001.
Several diagnostic tests are available, especially ELISA kits. These are designed to detect FHA and/or PT antibodies of IgG, IgA, or IgM. Some kits use a combination of antigens which lead to a higher sensitivity, but might also make the interpretation of the results harder, since one cannot know which antibody has been detected.
The organism is oxidase positive, but urease , nitrate reductase , and citrate negative. It is also not motile.
* ^ Heymann, David L. (ed): Pertussis; in Control of Communicable Diseases Manual. p. 457. American Public Health Association, Washington DC, 2008, ISBN 978-0-87553-189-2 * ^ Pink Book 2015 , Ch. 16: Pertussis * ^ Parkhill J, et al. (2003). "Comparative analysis of the genome sequences of Bordetella pertussis, Bordetella parapertussis and Bordetella bronchiseptica". Nat Genet. 35 (1): 32–40. PMID 12910271 . doi :10.1038/ng1227 . * ^ "Whooping Cough (Pertussis)". HPA. Retrieved 2009-04-12. * ^ Inaba, I. (1912). "Über den Bordet-Gengouschen Keuchhustenbacillus Übertragungsversuches des Keuchenhustens auf Tiere". Z Kinderheilkd. 4 (1): 252–264. doi :10.1007/BF02088879 . * ^ Bachamn, W.; Burghard, E. (1925). "Der Nachweis der Bordet–Gengouschen Bacillen und ihre ätiologische Bedeutung für den Keuchenhusten". Z Kinderheildk. 39 (5): 465–483. doi :10.1007/BF02225286 . * ^ Shibley GS, Hoelscher H (1934). "Studies on Whooping Cough : I. Type-Specific (S) and Dissociation (R) forms of Hemophilus Pertussis". J. Exp. Med. 60 (4): 403–18. PMC 2132401 . PMID 19870311 . * ^ Gustavsson OE, Röken BO, Serrander R (1990). "An epizootic of whooping cough among chimpanzees in a zoo". Folia Primatol. 55 (1): 45–50. PMID 2394416 . * ^ Warfel JM, Merkel TJ (2014). "The baboon model of pertussis: effective use and lessons for pertussis vaccines". Expert Rev Vaccines. 13 (10): 1241–52. PMID 25182980 . doi :10.1586/14760584.2014.946016 . * ^ Kingdon, Jonathan; Happold, David; Butynski, Thomas (2013). Primates. Mammals of Africa. 2. A&C Black. p. 51. ISBN 978-1-4081-8996-2 . * ^ Loomis, M.R. (1985). "Immunoprofylaxis in infant great apes". In Graham, C.E.; Bowen, J.A. Clinical management of infant great apes: proceedings of a workshop on clinical management of infant great apes, held during the IXth Congress of the International Primatological Society. Monographs in Primatology. 5. Liss. pp. 107–112. ISBN 0845134043 . * ^ Nieves DJ, Heininger U (2016). " Bordetella pertussis". Microbiology Spectrum. 4 (3). PMID 27337481 . doi :10.1128/microbiolspec.EI10-0008-2015 .
* Ray, C.G., ed. (2004). Sherris Medical Microbiology (4th ed.). McGraw Hill. ISBN 0-8385-8529-9 . * Todar, K. (2008). " Bordetella pertussis and Whooping Cough". Online Textbook of Bacteriology. Retrieved December 11, 2009.